CN113728672A

CN113728672A - Method and apparatus for measuring frequency in wireless communication system

Info

Publication number: CN113728672A
Application number: CN202080031414.4A
Authority: CN
Inventors: 金东建
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2019-04-26
Filing date: 2020-04-22
Publication date: 2021-11-30
Also published as: KR20200125355A

Abstract

A method of performing measurement performed by a User Equipment (UE), comprising receiving measurement configuration information for measurement in an idle mode or an inactive mode from a base station, starting a timer based on the measurement configuration information, and performing the measurement in the idle mode or the inactive mode while the timer is running, wherein the measurement configuration information is deleted when the timer expires in the idle mode or the inactive mode.

Description

Method and apparatus for measuring frequency in wireless communication system

Technical Field

The present disclosure relates to a method and apparatus for measuring and reporting a frequency in a wireless communication system.

Background

In order to meet the increasing demand for wireless data services after commercialization of fourth generation (4G) communication systems, efforts have been made to develop improved fifth generation (5G) communication systems or quasi-5G communication systems. For this reason, the 5G communication system or the quasi-5G communication system is referred to as a "super 4G network communication system" or a "post-evolution (LTE) system". The 5G communication system defined in the third generation partnership project (3GPP) is referred to as a New Radio (NR) system. To achieve high data rates, it is considered to implement a 5G communication system in an ultra high frequency millimeter wave (mmW) frequency band (e.g., 60GHz band). In the 5G communication system, in order to reduce propagation path loss and increase the propagation distance of the ultra-high frequency millimeter wave band, techniques such as beamforming, massive Multiple Input Multiple Output (MIMO), full-dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and massive antenna are studied and applied to the NR system. Further, in order to improve the network of the system, in the 5G communication system, development of technologies such as evolved small cell, advanced small cell, cloud radio access network (cloud RAN), ultra dense network, device-to-device communication (D2D), wireless backhaul, mobile network, cooperative communication, coordinated multipoint (CoMP), and interference cancellation is underway. Furthermore, in 5G communication systems, Advanced Coding Modulation (ACM) schemes such as hybrid Frequency Shift Keying (FSK) and Quadrature Amplitude Modulation (QAM) modulation (FQAM) or Sliding Window Superposition Coding (SWSC) are being developed, as well as enhanced network access schemes such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), or Sparse Code Multiple Access (SCMA).

The internet is evolving from a human-centric connection network through which humans create and consume information, to the internet of things (IoT) through which distributed elements, such as objects, exchange and process information. Internet of everything (IoE) technology is emerging, which is a technology in which IoT technology and big data processing technology are combined together through a connection with a cloud server. To implement IoT, technical requirements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and thus technologies for inter-object connection, such as sensor network, machine-to-machine (M2M) communication, or Machine Type Communication (MTC), have recently been studied. In an IoT environment, intelligent Internet Technology (IT) services may be provided that collect and analyze data generated by connected objects and create new value in human life. IoT may be applied to fields such as smart homes, smart buildings, smart cities, smart cars or networked cars, smart grids, healthcare, smart home appliances, and advanced medical services through fusion and integration of existing Information Technology (IT) and various industries.

Various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor networks, M2M communication, or MTC are implemented by 5G communication technologies such as beamforming, MIMO, or array antennas. The cloud RAN, which is an application of big data processing technology, may be an example of convergence of 5G technology and IoT technology.

Since the development of wireless communication systems can provide various services, methods for efficiently providing the services are required.

Disclosure of Invention

[ solution ]

According to an aspect of an exemplary embodiment, a communication method in wireless communication is provided.

[ advantageous effects ]

Aspects of the present disclosure provide an efficient communication method in a wireless communication system.

Drawings

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like reference numbers represent like parts:

fig. 1A is a diagram illustrating a structure of a Long Term Evolution (LTE) system according to an embodiment of the present disclosure;

fig. 1B is a diagram illustrating a radio protocol architecture in an LTE system according to an embodiment of the present disclosure;

fig. 1C is a diagram showing the structure of a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1D is a diagram illustrating a radio protocol architecture of a next generation mobile communication system according to an embodiment of the present disclosure;

Fig. 1E is a diagram for describing a procedure for configuring carrier aggregation by a User Equipment (UE) in a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1F is a diagram for describing a method in which a UE performs early frequency measurement and makes a fast frequency measurement result report in a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1H is a diagram for describing a method in which a UE performs early frequency measurement and makes a fast frequency measurement result report in a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1I is a diagram for describing a Radio Access Network (RAN) notification area update procedure according to an embodiment of the present disclosure;

fig. 1J is a diagram for describing a RAN notification area update procedure according to an embodiment of the present disclosure;

fig. 1K is a diagram for describing a procedure for a Radio Resource Control (RRC) inactive UE to fall back to RRC idle mode due to an indication of a next generation node b (gnb), according to an embodiment of the present disclosure;

fig. 1L is a diagram for describing an operation of a terminal performing RRC idle mode or RRC inactive mode frequency measurement and reporting a measurement result according to an embodiment of the present disclosure;

fig. 1M is a block diagram illustrating a structure of a terminal according to an embodiment of the present disclosure;

Fig. 1N is a block diagram illustrating the structure of a base station according to an embodiment of the present disclosure;

fig. 2A is a diagram showing the structure of an LTE system according to an embodiment of the present disclosure;

fig. 2B is a diagram illustrating a radio protocol architecture in an LTE system according to an embodiment of the present disclosure;

fig. 2C is a diagram showing the structure of a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 2D is a diagram illustrating a radio protocol architecture of a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 2E is a diagram for describing a procedure of whether the gbb configuration performs uplink data compression when the UE configures a network connection according to an embodiment of the present disclosure;

fig. 2F is a diagram depicting a data structure and a process for performing uplink data compression according to an embodiment of the disclosure;

fig. 2G is a diagram for describing an uplink data compression method according to an embodiment of the present disclosure;

fig. 2H is a diagram for describing decompression failure occurring in an uplink data compression method according to an embodiment of the present disclosure;

fig. 2I is a diagram for describing a Packet Data Convergence Protocol (PDCP) control Packet Data Unit (PDU) format suitable for a checksum failure handling method according to an embodiment of the present disclosure;

Fig. 2J is a diagram for describing an operation of a terminal receiving a PDCP layer according to an embodiment of the present disclosure;

fig. 2K is a block diagram illustrating a structure of a terminal according to an embodiment of the present disclosure; and

fig. 2L is a block diagram illustrating a structure of a base station according to an embodiment of the present disclosure.

Detailed Description

An apparatus and method for efficiently providing a service in a mobile communication system are provided.

Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the embodiments presented in this disclosure.

According to an embodiment of the present disclosure, a method of performing a measurement performed by a User Equipment (UE) includes: receiving measurement configuration information for measurement in an idle mode or an inactive mode from a base station; starting a timer based on the measurement configuration information; and performing the measurement in an idle mode or an inactive mode while the timer is running, wherein the measurement configuration information is deleted when the timer expires in the idle mode or the inactive mode.

The method may further comprise: transmitting a Radio Resource Control (RRC) resume request message to a base station; receiving a response message to the RRCRESUMeRequest message; and determining whether to continue performing the measurement based on the response message.

Determining whether to continue performing the measurement in the idle mode based on the response message may include stopping the running timer and deleting the measurement configuration information when the response message is an RRC setup message or an RRC recovery message.

Determining whether to continue performing the measurement in the idle mode based on the response message may include continuing performing the measurement in the idle mode or the inactive mode when the response message is the RRC reject message.

The method may further comprise: receiving a UEinformationRequest message for requesting a measurement result; transmitting a UE information response message including the measurement result; and discarding the measurement results.

The method may further include maintaining configuration information of a primary cell group (MCG) Scell or a Secondary Cell Group (SCG), wherein the response message includes information indicating whether to reconstruct the configuration information of the Scell or SCG, wherein the configuration information of the Scell or SCG is released or reconstructed based on the information indicating whether to reconstruct the configuration information of the Scell or SCG.

The method may further comprise: performing a cell reselection procedure; when the cell selected based on the cell reselection procedure is not a validity area, the timer is stopped and the measurement configuration information is discarded.

The method may further comprise: performing a cell reselection procedure; when the cell selected based on the cell reselection procedure is a cell using another Radio Access Technology (RAT), the running timer is stopped and the measurement configuration information is discarded.

The method may also include maintaining the running timer and maintaining the measurement configuration information when the UE transitions from the inactive mode to the idle mode.

The method may further include not stopping the running timer or deleting the measurement configuration information when the UE fails to find a cell to camp on or fails to select a cell.

According to another embodiment of the present disclosure, a User Equipment (UE) for performing measurements in an idle mode or an inactive mode includes: a transceiver; and a processor coupled with the transceiver and configured to receive measurement configuration information for measurement in an idle mode or an inactive mode from the base station, start a timer based on the measurement configuration information, perform the measurement in the idle mode or the inactive mode while the timer is running, and remove the measurement configuration information when the timer expires in the idle mode or the inactive mode.

The processor may be further configured to send a Radio Resource Control (RRC) resume request message to the base station, receive a response message to the RRCResumeRequest message, and determine whether to continue to perform the measurement based on the response message.

The processor may be further configured to stop the running timer and discard the measurement configuration information when the response message is an RRC setup message or an RRC recovery message.

The processor may be further configured to: when the response message is an RRC reject message, the measurement is continuously performed in the idle mode or the inactive mode.

The processor may be further configured to receive a UE information request message for requesting the measurement result, send a UE information response message including the measurement result, and discard the measurement result.

The processor may be further configured to maintain primary cell group (MCG) Scell or Secondary Cell Group (SCG) configuration information, wherein the response message includes information indicating whether the Scell or SCG configuration information is reconstructed by the reconfiguration, wherein the Scell configuration information is released or reconstructed based on the information indicating whether the Scell or SCG configuration information is reconstructed by the reconfiguration.

The processor may be further configured to: performing a cell reselection procedure; and stopping the timer and discarding the measurement configuration information when the cell selected based on the cell reselection procedure is not the validity area.

The processor may be further configured to: performing a cell reselection procedure; and stopping the running timer and discarding the measurement configuration information when the cell selected based on the cell reselection procedure is a cell using another Radio Access Technology (RAT).

The processor may be further configured to maintain the running timer and maintain the measurement configuration information when the UE transitions from the inactive mode to the idle mode.

The processor may be further configured to not stop the running timer or remove measurement configuration information when the UE fails to find a cell to camp on or fails to select a cell.

Before proceeding with the following detailed description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "associated with … …" and "associated therewith," as well as derivatives thereof, may mean to include, be included, interconnected with … …, inclusive, included, connected to or connected with … …, coupled to or coupled with … …, communicable with … …, cooperative with … …, interleaved, juxtaposed, adjacent, bound to or bound with … …, have the properties of … …, and the like; and the term "controller" refers to any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or a combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

Further, the various functions described below may be implemented or supported by one or more computer programs, each formed from computer-readable program code, embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in suitable computer readable program code. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as Read Only Memory (ROM), Random Access Memory (RAM), a hard disk drive, a Compact Disc (CD), a Digital Video Disc (DVD), or any other type of memory. "non-transitory" computer readable media exclude wired, wireless, optical, or other communication links that transmit transitory electrical or other signals. A non-transitory computer readable medium includes media that can permanently store data, as well as media that can store data and subsequently rewrite data, such as a rewritable optical disk or an erasable storage device.

Definitions for certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[ modes for the invention ]

Figures 1A through 2L, discussed below, and the various embodiments used to describe the principles disclosed in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system or device.

Throughout the disclosure, the expression "at least one of a, b or c" means only a, only b, only c, both a and b, both a and c, both b and c, all a, b and c, or variants thereof.

Examples of terminals may include User Equipment (UE), Mobile Stations (MS), cellular phones, smart phones, computers, and multimedia systems capable of performing communication functions.

In this disclosure, a controller may also be referred to as a processor.

Throughout the specification, a layer may also be referred to as an entity.

The operation of the present disclosure will be described in detail with reference to the accompanying drawings. While the present disclosure is described, a detailed description of related well-known functions or configurations which may obscure the gist of the present disclosure is omitted. The terms used herein are terms defined in consideration of functions in the present disclosure, but these terms may vary according to the intention of a user or operator, precedent, and the like. Therefore, the terms used herein must be defined based on the meanings of the terms as well as the description throughout the specification.

Hereinafter, terms indicating a connection node, terms indicating a network entity, terms indicating a message, terms indicating an interface between network entities, and terms indicating various identification information used by the following description are exemplified for convenience of explanation. Accordingly, the present disclosure is not limited to terms that will be described later, but other terms indicating objects having the same technical meaning may be used.

Hereinafter, for convenience of explanation, the present disclosure uses terms and names defined in the third generation partnership project long term evolution (3GPP LTE) standard. However, the present disclosure is not limited to the above terms and names, and may also be applied to systems that comply with other standards.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. While the present disclosure is described, a detailed description of related well-known functions or configurations which may obscure the gist of the present disclosure is omitted. The terms used herein are terms defined in consideration of functions in the present disclosure, but these terms may vary according to the intention of a user or operator, precedent, and the like. Therefore, the terms used herein must be defined based on the meanings of the terms as well as the description throughout the specification. Hereinafter, the base station, which is an entity for allocating resources for the terminal, may include at least one of an eNode B, a Node B, a Base Station (BS), a radio access unit, a base station controller, or a Node on the network. In this disclosure, for ease of explanation, eNB may be used interchangeably with gNB. That is, a base station described as an eNB may refer to a gbb. A terminal may include a User Equipment (UE), a Mobile Station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing communication functions. In the present disclosure, Downlink (DL) refers to a radio link for transmitting signals from a base station to a terminal, and Uplink (UL) refers to a radio link for transmitting signals from a terminal to a base station. Furthermore, although an LTE/LTE-advanced (LTE-a) system is described below as an example, embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, embodiments of the present disclosure may be applied to fifth generation (5G) mobile communication technologies (e.g., 5G New Radio (NR)) developed after LTE-a. Furthermore, embodiments of the present disclosure may also be applied to other communication systems by making some changes or modifications therein, without departing from the spirit and scope of the present disclosure.

In order to support a service with a high data rate and low latency in a next generation mobile communication system, a base station needs to rapidly configure Carrier Aggregation (CA) or Dual Connectivity (DC) in a terminal. However, in order to configure such a technique in a terminal, a frequency measurement result of the terminal may be required. Therefore, a method of receiving a fast frequency measurement result report of a terminal may be required.

When a Radio Resource Control (RRC) idle mode terminal, which configures and performs fast frequency measurement in an RRC idle mode, transitions to an RRC inactive mode for some reason, or when an RRC inactive mode terminal, which configures and performs fast frequency measurement in an RRC inactive mode, transitions to an RRC idle mode, an efficient method for determining whether to continue performing frequency measurement, stop frequency measurement, or perform a different procedure according to the reason of state transition may be required.

Embodiments of the present disclosure provide a method in which an RRC idle mode or RRC inactive mode terminal can quickly report a frequency measurement result to a base station in a next generation mobile communication system. The base station according to the embodiment of the present disclosure may rapidly configure carrier aggregation or dual connectivity in the terminal. Specifically, according to an embodiment of the present disclosure, a terminal may perform frequency measurement based on frequency configuration information that is pre-configured before configuring a network connection. A terminal according to an embodiment of the present disclosure may immediately report a frequency measurement result when configuring a network connection. Accordingly, the base station according to an embodiment of the present disclosure may rapidly configure Carrier Aggregation (CA) or Dual Connectivity (DC) in the terminal. Further, when an RRC idle mode terminal configured and performing early frequency measurement in an RRC idle mode transitions to an RRC inactive mode for some reason, or when an RRC inactive mode terminal configured and performing early frequency measurement in an RRC inactive mode transitions to an RRC idle mode, embodiments of the present disclosure may provide a method of effectively measuring a frequency or a method of processing frequency configuration information and a frequency measurement result.

The present disclosure may provide a method in which an RRC inactive mode terminal may perform frequency measurement before configuring an RRC connection to a network, and may make a fast frequency measurement result report at or immediately after configuring the RRC connection, so that a base station may quickly configure Carrier Aggregation (CA) or Dual Connectivity (DC) in the terminal.

The specific methods provided by the present disclosure can be summarized as follows.

In an embodiment of the present disclosure, a terminal in an RRC connected mode may receive an rrcreelease message from a base station and may release an RRC connection. In this case, when the terminal receives the frequency measurement configuration information and the indication of the transition to the RRC idle mode or the RRC inactive mode, the terminal may perform the frequency measurement in the RRC idle mode or the RRC inactive mode for the configured duration or time. However, information on a list of frequencies to be measured may not be included in the frequency measurement configuration information. In this case, when performing the cell reselection procedure, if frequency measurement configuration information for frequency measurement of the RRC idle mode or RRC inactive mode terminal is broadcast in the camped cell, the terminal may receive the information and may perform the frequency measurement. A value of a first timer indicating a time at which the terminal will perform the frequency measurement may be configured based on the configured duration or time. When a duration or time during which the frequency measurement is to be performed is configured in the rrcreelease message, the terminal may start a timer based on the value of the first timer. Since the time of the first timer, at which the terminal can perform the frequency measurement, is limited from the time point of receiving the rrcreelease message, the battery power of the terminal can be saved.

In another method, the terminal may start the first timer when the terminal receives a list of frequencies to be measured in the frequency configuration information. For example, when the terminal receives the rrcreelease message and the frequency configuration information includes the value of the first timer but does not include the frequency measurement list, the terminal may receive the frequency measurement list from the system information. In this case, the terminal may start the first timer when the terminal receives the frequency measurement list from the system information. In this case, it may not be good in saving battery power of the terminal because the terminal must restart the first timer each time the terminal receives new system information. However, the terminal may make a fast frequency measurement result report even when the terminal moves and connects to another cell. When the first timer expires, the terminal may release or discard the frequency configuration information received from the rrcreelease message or the system information, and may stop the frequency measurement result.

Further, the base station may define and configure the value of the second timer by using the rrcreelease message to indicate how long the frequency measurement result value measured by the terminal is valid. For example, when the terminal receives the rrcreelease message, the terminal may store and use the timer value for a second timer that operates based on the value of the second timer. The second timer may start when the terminal receives the rrcreelease message, and the terminal may determine that the frequency measurement result measured when the second timer expires is invalid and may discard the frequency measurement result. That is, the terminal may not report the frequency measurement result to the base station. In another approach, the second timer may be started when the first timer expires or stops. This is because, since the frequency measurement result may be continuously updated while the frequency measurement is performed, the terminal may start the second timer from a point in time when the first timer expires or stops and the frequency measurement stops to indicate the valid duration of the latest frequency measurement result. The terminal may determine that the frequency measurement result measured when the second timer expires is invalid, and may discard the frequency measurement result. That is, the terminal may not report the frequency measurement result to the base station. In another embodiment, the terminal may define and use the function of the second timer to be performed by the first timer.

The terminal, which is in the RRC idle mode or the RRC inactive mode and receives the rrcreelease message, may perform frequency measurement based on frequency configuration information received from the rrcreelease message or frequency configuration information received from system information. When a network connection is required due to the generation of uplink data or the reception of a paging message, the terminal may determine whether a fast frequency measurement result can be reported in system information of a camped cell, and may complete a random access procedure. Further, the terminal may transmit a message 3(RRCSetupRequest or rrcresumererequest) to the base station, and may receive a message 4(RRCSetup or RRCResume) from the base station in response to the message 3. When the terminal transmits a message 5(RRCSetupComplete or RRCResumeComplete) to the base station, the terminal may inform that the fast frequency measurement result exists in the message 5 through an indicator. In this case, the base station may transmit a separate message for requesting the frequency measurement result to the terminal, and the terminal may configure the separate message including the frequency measurement result in response to the message of the base station and may transmit the separate message to the base station, and may release and discard the stored frequency measurement result and frequency measurement configuration information.

The present disclosure may also provide a method of more rapidly measuring and reporting the frequency of the RRC inactive mode. When the terminal performs frequency measurement in the RRC inactive mode and needs to be connected to the network for some reason, the terminal may perform and complete a random access procedure and may then transmit a message 3 (e.g., RRCResumeRequest) to the base station. In this case, the terminal may identify the indicator of message 4, may cause the frequency measurement result to be included in message 5 (e.g., rrcresumite), and may send message 5, since the RRC inactive mode terminal may resume or activate the security procedures (encryption and decryption or integrity protection and verification) of signaling radio bearer SRB1 when sending the RRCResumeRequest message, the RRC inactive mode terminal may increase the security level and receive message 4 when receiving message 4, and may increase the security level and report the frequency measurement result of message 5 when reporting the frequency measurement result of message 5, the base station may cause the carrier aggregation configuration or dual connectivity configuration information to be included in the RRC message by using the above information, and may transmit the RRC message so that the terminal may quickly restart, change, or newly configure the carrier aggregation or dual connectivity.

Further, the present disclosure may provide an efficient signaling method in which a network or a base station may more efficiently configure or update frequency measurement configuration information in a terminal having mobility in an RRC inactive mode.

The most significant difference between the RRC idle mode terminal and the RRC inactive mode terminal is that the RRC inactive mode terminal can store a terminal context in the base station and the terminal and can rapidly configure a connection by reusing the terminal context, and the RRC inactive mode terminal can update an area in which the RRC inactive mode must be maintained from the network by periodically updating the RAN notification area.

In an embodiment of the present disclosure, when an RRC connected mode terminal receives frequency measurement configuration information from a base station and an indication to release an RRC connection and transition to an RRC inactive mode, the terminal may perform frequency measurement for a configured duration or time in the RRC inactive mode. When the RRC inactive mode terminal leaves the configured RAN notification area, the RRC inactive mode terminal may configure a network connection to perform a RAN Notification Area Update (RNAU) procedure.

In this case, for a terminal performing network connection to update a RAN notification area, the base station may configure or update a new frequency measurement configuration, or may instruct the terminal to maintain frequency measurement, according to an embodiment of the present disclosure. The base station may retrieve the terminal context from the source base station through the connection recovery identifier indicated by the terminal in message 3) (RRCResumeRequest), and may determine whether the terminal is to perform the frequency measurement configuration in the RRC inactive mode. In another method, when the terminal transmits message 3 to update the RAN notification area, the terminal may cause an indicator indicating that frequency measurement will be performed in the RRC inactive mode, that timer T331 expires or is running, or that new frequency configuration information needs to be included in message 3, and may transmit message 3 to the base station to indicate the information to the base station. When the base station determines whether the terminal can perform frequency measurement in the RRC inactive mode and then transmits an RRC message (e.g., an rrcreelease message) including information for updating the RAN notification area to the terminal, the base station may cause new frequency measurement configuration information to be included in the RRC message and may transmit and configure the RRC message. The new frequency measurement configuration information may include configuration information such as a list of frequencies to measure, a list of physical cell identifiers, a measurement duration, or a validity area for measurement (e.g., a list of cell identifiers).

When the terminal receives the RRCRelease message in the RAN notification area update procedure, if the fast frequency measurement configuration information is included in the message, the terminal may release or discard (remove or delete) the stored frequency measurement configuration information or frequency measurement result, and may perform frequency measurement by storing, updating, and applying the new fast frequency measurement configuration information. In another method, when only the value of the frequency measurement duration or the timer is configured in the fast frequency measurement configuration information, the terminal may restart (or start) the timer based on the value and may continue to perform the frequency measurement configuration while maintaining the existing frequency configuration information. Alternatively, the terminal may start a timer based on the value, may release or delete existing frequency configuration information, may receive system information from the camping cell through a cell reselection procedure, and may perform frequency measurement by applying the frequency configuration information when the frequency configuration information is included in the received information. In another method, the base station may define a new indicator in the rrcreelease message and may indicate whether to continue performing frequency measurement, stop frequency measurement, or release frequency measurement configuration information by using existing frequency measurement configuration information. In another method, the terminal may release the existing frequency configuration information only when the frequency measurement configuration information is included in the rrcreelease message, and the terminal may maintain and apply the existing frequency configuration information when the frequency configuration information is not included in the rrcreelease message.

Further, according to an embodiment of the present disclosure, when a base station or a cell to which the terminal is connected may support RRC idle mode or inactive mode frequency measurement, or when the system information may indicate that RRC idle mode or inactive mode frequency measurement is supported, and when the frequency measurement result may be reported to the base station, the terminal may stop a timer (i.e., T331) for RRC idle mode or inactive mode frequency measurement, and may discard or release the frequency measurement configuration information or discard the frequency measurement result.

Further, according to an embodiment of the present disclosure, the RRC inactive mode or RRC idle mode terminal may configure a separate region (e.g., validity region) for performing frequency measurement. That is, according to an embodiment of the present disclosure, the terminal may perform frequency measurement in the RRC inactive mode or the RRC idle mode only within the validity region, and when outside the validity region, the terminal may stop the timer, may release the frequency measurement configuration information, may discard the frequency measurement result, or may stop the frequency measurement. The validity area may be indicated by a list of physical cell identifiers or a list of RAN notification area indicators. Embodiments of the present disclosure may provide a method of configuring a validity area and a RAN notification area in an RRC inactive mode terminal, respectively, and a method of allowing the RRC inactive mode terminal to use the RAN notification area instead of the validity area (or use the validity area instead of the RAN notification area) by using an indicator to reduce a burden on the terminal and reduce signaling overhead. This is because, when a separate validity area is indicated to the terminal, the terminal may have a burden of maintaining and updating a tracking area, maintaining and updating a RAN notification area, and maintaining and managing the validity area.

Further, according to an embodiment of the present disclosure, when frequency measurement configuration information is indicated to an RRC inactive mode or RRC idle mode terminal, the base station may configure a separate timer according to a frequency configuration group or a radio access technology, or for each frequency, cell, or beam. That is, according to the embodiments of the present disclosure, a duration or timer value indicating how long frequency measurement is to be performed for an LTE frequency (each frequency or cell) may be separately configured, a duration or timer value indicating how long frequency measurement is to be performed for an NR frequency (each frequency, cell or beam) may be separately configured, and a separate timer and a separate duration may be configured for each frequency configuration group.

Further, embodiments of the present disclosure may provide a method of processing frequency measurement configuration information or frequency measurement results according to a state change of an RRC inactive mode and determining whether to continue performing a frequency measurement operation. That is, embodiments of the present disclosure may specifically provide for terminal operation when a terminal transitions from an RRC inactive mode to an RRC idle mode.

Fig. 1A is a diagram illustrating a structure of an LTE system according to an embodiment of the present disclosure.

Referring to fig. 1A, a radio access network of an LTE system may include evolved node bs (enbs) (node bs or base stations) 1A-05, 1A-10, 1A-15, and 1A-20, Mobility Management Entities (MMEs) 1A-25, and serving gateways (S-GWs) 1A-30. User Equipments (UEs) 1a-35 can connect to external networks through ENBs 1a-05, 1a-10, 1a-15, and 1a-20 and S-GWs 1 a-30.

In FIG. 1 at 1a, each of the ENBs 1a-05, 1a-10, 1a-15, and 1a-20 may correspond to an existing node B of a Universal Mobile Telecommunications System (UMTS). Each ENB may be connected to the UEs 1a-35 through a radio channel and may perform more complicated functions than existing node bs. Since all user traffic data including real-time services such as voice over internet protocol (VoIP) is served through a shared channel in the LTE system, an entity for collecting and scheduling buffer status information, available transmission power status information, and channel status information of UEs may be required. And each of the ENBs 1a-05 to 1a-20 may serve as such an entity. One ENB may generally control a plurality of cells. For example, to achieve a data rate of 100Mbps, the LTE system may use Orthogonal Frequency Division Multiplexing (OFDM) of a 20MHz bandwidth as a radio access technology. Further, Adaptive Modulation and Coding (AMC) for determining a modulation scheme and a channel coding rate according to the channel status of the UEs 1A-35 may be applied. The S-GW 1a-30 is an entity for providing data bearers and may generate or remove data bearers under the control of the MME 1 a-25. The MME 1a-25, which is an entity for performing various control functions as well as mobility management functions on the UE 1a-35, may be connected to a plurality of ENBs.

Fig. 1B is a diagram illustrating a radio protocol architecture in an LTE system according to an embodiment of the present disclosure.

Referring to FIG. 1B, a radio protocol architecture of the LTE system includes Packet Data Convergence Protocol (PDCP) layers 1B-05 and 1B-40, Radio Link Control (RLC) layers 1B-10 and 1B-35, and Medium Access Control (MAC) layers 1B-15 and 1B-30 for the UE and the ENB, respectively. The PDCP layers 1b-05 and 1b-40 may be responsible for, for example, IP header compression/decompression. The main functions of each PDCP layer can be summarized as follows.

Header compression and decompression: robust header compression only (ROHC)

-transmitting user data

In-order delivery of upper layer Packet Data Units (PDUs) in PDCP re-establishment procedure for RLC Acknowledged Mode (AM)

For separate bearers in DC (RLC AM only supported): PDCP PDU routing for transmission and PDCP PDU reordering for reception

-duplicate detection of lower layer Service Data Units (SDUs) in PDCP re-establishment procedure for RLC AM

-retransmitting PDCP SDUs at handover and PDCP PDUs in PDCP data recovery procedure for RLC AM for separate bearers in DC

-encryption and decryption

Timer-based SDU discard in uplink

Each of the RLC layers 1b-10 and 1b-35 can perform an automatic repeat request (ARQ) operation by reconfiguring a PDCP Packet Data Unit (PDU) to an appropriate size. The main functions of each RLC layer can be summarized as follows.

-transmission of upper layer PDU

Error correction by ARQ (for AM data Transmission only)

Concatenation, segmentation and reassembly of RLC SDUs (for Unacknowledged Mode (UM) and AM data transmission only)

Re-segmentation of RLC data PDUs (for AM data transfer only)

Reordering of RLC data PDUs (for UM and AM data transfer only)

Duplicate detection (for UM and AM data transmission only)

Protocol error detection (for AM data transmission only)

RLC SDU discard (for UM and AM data transmission only)

RLC re-establishment

The MAC layers 1b-15 and 1b-30 are connected to various RLC layers configured in one UE, and can multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUs from the MAC PDUs. The main functions of each MAC layer can be summarized as follows.

Mapping between logical channels and transport channels

-multiplexing/demultiplexing MAC SDUs belonging to one or different logical channels into/from Transport Blocks (TBs) delivered from the physical layer on transport channels

-scheduling information reporting

Error correction by Hybrid ARQ (HARQ)

-priority handling between logical channels of one UE

-prioritization among UEs by dynamic scheduling

-multimedia broadcast/multicast service (MBMS) identification

-transport format selection

-filling

Each of the Physical (PHY) layers 1b-20 and 1b-25 may channel-encode and modulate upper layer data into OFDM symbols and transmit the OFDM symbols through a radio channel, or demodulate and channel-decode OFDM symbols received through the radio channel and deliver the OFDM symbols to the upper layer.

Fig. 1C is a diagram showing the structure of a next-generation mobile communication system (e.g., an NR system or a 5G communication system) according to an embodiment of the present disclosure.

Referring to fig. 1C, a radio access network of a next generation mobile communication system (e.g., NR or 5G system) may include a new radio node B (NR gbb or NR base station) 1C-10 and a new radio core network (NR CN) 1C-05. The new wireless user equipment (NR UE)1c-15 can connect to an external network through NR gNB 1c-10 and NR CN 1 c-05.

In fig. 1C, nrgnbs 1C-10 correspond to evolved node bs (enbs) of the existing LTE system. The NR gNB 1c-10 can connect to the NR UE 1c-15 through a radio channel and can provide better service than the existing node B. Since all user traffic data is served through a shared channel in the next generation mobile communication system, an entity for collecting and scheduling buffer status information, available transmission power status information, and channel status information of UEs may be required, and the NR gbb 1c-10 may be used as such an entity. One NR gbb may generally control a plurality of cells. The next generation mobile communication system may currently have a bandwidth greater than the maximum bandwidth of the existing LTE to achieve an ultra-high data rate, may use Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology, and may additionally use a beamforming technology. Further, Adaptive Modulation and Coding (AMC) for determining a modulation scheme and a channel coding rate according to the channel status of the NR UEs 1c-15 may be applied. The NR CN 1c-05 may perform functions such as mobility support, bearer configuration, and quality of service (QoS) configuration. The NR CN 1c-05, which is an entity for performing various control functions and mobility management functions on the NR UE 1c-15, may be connected to a plurality of base stations. Further, the next generation mobile communication system can cooperate with the existing LTE system, and the NR CN 1c-05 can be connected to the MME1c-25 through a network interface. MME1c-25 may connect to eNB 1c-30 as an existing base station.

Fig. 1D is a diagram illustrating a radio protocol architecture of a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 1D, the radio protocol architecture of the next generation mobile communication system may include NR Service Data Adaptation Protocol (SDAP) layers 1D-01 and 1D-45, NR PDCP layers 1D-05 and 1D-40, NR RLC layers 1D-10 and 1D-35, and NR MAC layers 1D-15 and 1D-30 for the UE and the NR gbb.

The primary functions of each of the NR SDAP layers 1d-01 and 1d-45 may include some of the following functions.

-transmission of user plane data

-mapping between QoS flows and Data Radio Bearers (DRBs) for both DL and UL

Marking QoS flow Identifiers (IDs) in DL and UL packets

-reflected QoS flows to DRB mapping for UL SDAP PDUs

For the SDAP layer, the information indicating whether to use a header of the SDAP layer or to use a function of the SDAP layer may be configured for the UE by using a Radio Resource Control (RRC) message per PDCP layer, per bearer, or per logical channel. When the SDAP header is configured, the SDAP layer may instruct the UE to update or reconfigure the uplink and downlink QoS flows and the data bearer mapping information by using a 1-bit non-access stratum (NAS) reflection QoS indicator and a 1-bit Access Stratum (AS) reflection QoS indicator of the SDAP header. The SDAP header may include QoS flow ID information indicating QoS. The QoS information may be used as data processing priority information or scheduling information to smoothly support a service.

The main functions of each of the NR PDCP layers 1d-05 and 1d-40 may include some of the following functions.

Header compression and decompression: ROHC only

-transmitting user data

In-order delivery of upper layer PDUs

Out-of-order delivery of upper layer PDUs

-PDCP PDU reordering for reception

Duplicate detection of lower layer SDU

-retransmission of PDCP SDU

-encryption and decryption

Timer-based SDU discard in uplink

In the above description, the reordering function of the NR PDCP layer may refer to a function of reordering PDCP PDUs received from a lower layer based on PDCP Sequence Numbers (SNs), and may include a function of delivering reordered data to an upper layer in order or out of order, a function of recording lost PDCP PDUs by reordering the received PDCP PDUs, a function of reporting status information of the lost PDCP PDUs to a transmitter, and a function of requesting retransmission of the lost PDCP PDUs.

The main functions of each of the NR RLC layers 1d-10 and 1d-35 may include some of the following functions.

-transmission of upper layer PDU

In-order delivery of upper layer PDUs

Out-of-order delivery of upper layer PDUs

Error correction by ARQ

Concatenation, segmentation and reassembly of RLC SDUs

-segmentation of RLC data PDUs

Reordering of RLC data PDUs

-duplicate detection

-protocol error detection

RLC SDU discard

RLC reconstruction

In the above description, the in-order delivery function of the NR RLC layer may refer to a function of sequentially delivering RLC SDUs received from a lower layer to an upper layer, and may include at least one of the following functions: a function of reassembling a plurality of RLC SDUs segmented from one RLC SDU and delivering the reassembled RLC SDU when the segmented RLC SDU is received, a function of reordering the received RLC PDUs based on RLC SN or PDCP SN, a function of recording missing RLC PDUs by reordering the received RLC PDUs, a function of reporting status information of the missing RLC PDUs to a transmitter, a function of requesting retransmission of the missing RLC PDUs, a function of delivering only RLC SDUs preceding the missing RLC SDU in order to an upper layer when there is the missing RLC SDU, and a function of delivering all RLC SDUs received before the timer is started to an upper layer in order despite the missing RLC SDUs when a certain timer expires, or a function of delivering all RLC SDUs received until the current time in order to an upper layer, although there is a missing RLC SDU when a certain timer expires. Further, the NR RLC layer may process RLC PDUs in the order of reception (in the order of arrival regardless of SNs) and deliver the RLC PDUs out of order (out of order delivery) to the PDCP layer, or reassemble segmented RLC PDUs received or stored in a buffer into the entire RLC PDU, process and deliver the RLC PDUs to the PDCP layer. The NR RLC layer may have no concatenation function, and the concatenation function may be performed by the NR MAC layer or may be replaced by a multiplexing function of the NR MAC layer.

In the above description, the out-of-order delivery function of the NR RLC layer refers to a function of directly delivering RLC SDUs received from a lower layer to an upper layer out of order, and may include a function of reassembling a plurality of RLC SDUs segmented from one RLC SDU and delivering the reassembled RLC SDU when the segmented RLC SDU is received, and a function of recording missing RLC PDUs by storing RLC SNs or PDCP SNs of the received RLC PDUs and reordering the received RLC PDUs.

Each of the NR MAC layers 1d-15 and 1d-30 may be connected to a plurality of NR RLC layers configured for one UE, and the main functions of each NR MAC layer may include some of the following functions.

Mapping between logical channels and transport channels

-multiplexing/demultiplexing of MAC SDUs

-scheduling information reporting

Error correction by HARQ

-priority handling between logical channels of one UE

-prioritization among UEs by dynamic scheduling

-MBMS service identification

-transport format selection

-filling

Each of the NR PHY layers 1d-20 and 1d-25 may channel-encode and modulate upper layer data into OFDM symbols and transmit the OFDM symbols through a radio channel, or may demodulate and channel-decode OFDM symbols received through a radio channel and deliver the OFDM symbols to the upper layer.

In the next generation mobile communication system, the UE may perform frequency measurement while performing a cell reselection procedure in the RRC idle mode. The frequency measurement performed by the UE when performing the cell reselection procedure may refer to intra-frequency measurement of a frequency broadcasted in the camped cell or a frequency configured by the gNB, serving cell measurement, or primary cell (Pcell) measurement. However, the UE may not perform inter-frequency measurement except for intra-frequency measurement or serving cell measurement, and may not report the frequency measurement result to the network separately.

That is, when the UE finds a suitable cell by performing a cell reselection procedure, camps on the suitable cell, and then transitions to the RRC connected mode by performing an RRC connection configuration procedure, the gNB may perform configuration of measurements with respect to the RRC connected mode UE. In this case, the gNB may configure the UE with at least one of: which frequencies (e.g., a frequency list) or which frequency bands are to be measured, what order is to be used to perform the measurement by configuring a priority of each frequency, which beam is to be measured, which filtering method is used to measure the strength of the frequency when measuring the frequency (e.g., L1 filtering, L2 filtering), L3 filtering, or a calculation method using coefficients), which event or condition is used to initiate the measurement when measuring the frequency, which criterion is used to perform the measurement compared to the current serving cell (or the frequency currently camped on), which event or condition is used to report the frequency result of the measurement, which criterion or condition is to be satisfied to report the frequency compared to the current serving cell (or the frequency currently camped on), or which period is used to report the frequency measurement result. The UE may measure the corresponding frequency according to the frequency configuration configured by the gNB, and may report the frequency measurement result to the gNB according to the corresponding event or condition. The gNB may determine whether to aggregate frequency carriers or apply dual connectivity to the UE by using the frequency measurement results received from the UE.

Embodiments of the present disclosure may provide a method in which a UE may perform frequency measurement in an RRC idle mode or an RRC inactive mode before transitioning to an RRC connected mode, indicate the measurement result to a gNB when the UE may configure network connection, and may quickly report the frequency measurement result by entering the RRC connected mode in a next generation mobile communication system. Based on the method, the gNB may quickly configure frequency carrier aggregation or dual connectivity in the UE based on the results of the UE measurements in the RRC idle mode or the RRC inactive mode.

Specifically, when the gNB converts an RRC connected mode UE in which a network connection is configured into an RRC idle mode or an RRC inactive mode, the gNB may configure, in an RRC message, frequency information of frequencies to be measured in the RRC idle mode or the RRC inactive mode, and time (or duration) information of frequencies to be measured by the UE in the RRC idle mode or the RRC inactive mode, or area information (or a cell list) of areas in which the UE is to measure frequencies in the RRC idle mode or the RRC inactive mode, and may instruct the UE to perform frequency measurement in the RRC idle mode or the RRC inactive mode. In addition, the UE may read system information of a new camped cell by performing a cell reselection operation whenever the UE moves. The UE may perform a procedure of determining whether to continue or end frequency measurement in the RRC idle mode or the RRC inactive mode, extend a measurement duration (e.g., restart a timer), report a frequency measurement result, or discard a frequency measurement result according to system information. The next generation mobile communication system according to the embodiment of the present disclosure may provide efficient UE operation through the above-described operation.

Examples of bearers of the present disclosure may include Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs). The UM DRB may refer to a DRB using an RLC layer operating in an Unacknowledged Mode (UM), and the AM DRB may refer to a DRB using an RLC layer operating in an Acknowledged Mode (AM).

Fig. 1E is a diagram for describing a procedure in which a UE configures carrier aggregation in a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 1E, a procedure for configuring a UE to switch from an RRC idle mode or an RRC inactive mode to an RRC connected mode and carrier aggregation in a next generation mobile communication system will be described.

For particular reasons, the gNB may transition the RRC connected mode UE, which configures the network connection, to an RRC idle mode or an RRC inactive mode. In embodiments of the present disclosure, particular reasons may include lack of scheduling resources for the gNB, or suspension of data transmission/reception to/from the UE for a particular period of time.

In operation 1e-05, the gNB may send a rrcreelease (RRC release) message to the UE and may indicate the UE as an RRC idle mode or an RRC inactive mode. The gNB may instruct the UE to transition to the RRC inactive mode in the rrcreelease message by using an indicator (suspend-config), and the UE may transition to the RRC idle mode when the indicator (suspend-config) is not included in the rrcreelease message. Thus, in operations 1e-10, the UE may transition to an RRC idle mode or an RRC inactive mode.

When a network connection is required for some reason, in operations 1e-15 and 1e-20, a UE transitioning to an RRC idle mode or an RRC inactive mode may perform a random access procedure and may receive a random access response. Also, in operations 1e-25 to 1e-40, the UE may request RRC connection configuration and may perform the RRC connection configuration by receiving an RRC message.

More specifically, in operations 1e-25, the UE may establish backward transmission synchronization with the gNB through a random access procedure and may transmit an RRCSetupRequest (RRC establishment request) message to the gNB. The RRCSetupRequest message may include a reason for configuring a connection to an identifier of the UE (estipalimincause).

In operations 1e-30, the gNB may send a RRCSetup message in order for the UE to configure the RRC connection. The RRCSetup message may include at least one of configuration information for each logical channel, configuration information for each bearer, configuration information of the PDCP layer, configuration information of the RLC layer, or configuration information of the MAC layer.

The gNB may assign a bearer identifier (e.g., SRB identifier or DRB identifier) to each bearer by using the RRCSetup message and may indicate PDCP layer configuration, RLC layer configuration, MAC layer configuration, and PHY layer configuration for each bearer. In addition, the gNB may configure a length (e.g., 12 bits or 18 bits) of a PDCP sequence number used in the PDCP layer for each bearer, and may configure a length (e.g., 16 bits, 12 bits or 18 bits) of an RLC sequence number used in the RLC layer in an RRCConnectionSetup message. Further, the gNB may indicate whether a header compression and decompression protocol is used for each bearer in uplink or downlink of the PDCP layer, and may indicate whether to perform an integrity protection or authentication procedure in the RRCConnectionSetup message. Further, the gNB may indicate whether to perform an out-of-order delivery function in the PDCP layer.

In operations 1e-40, the UE configuring the RRC connection may send a RRC setup complete message to the gNB. The RRCSetupComplete message may include a SERVICE REQUEST message, which is a control message through which the UE REQUESTs access for bearer configuration of a SERVICE and a mobility management function (AMF) or a Mobility Management Entity (MME). The gNB may transmit a SERVICE REQUEST message included in an rrcconnectionsetupcomplete message to the AMF or MME, and the AMF or MME may determine whether to provide the SERVICE requested by the UE.

When the AMF or MME determines to provide the service requested by the UE, the AMF or MME may send an INITIAL CONTEXT SETUP REQUEST message to the gNB. The INITIAL CONTEXT SETUP REQUEST message may include information such as quality of service (QoS) information to be applied when configuring a Data Radio Bearer (DRB) and security-related information (e.g., a security key or a security algorithm) to be applied to the DRB.

In operations 1e-45, the gNB may transmit/receive a SecurityModeCommand message and a SecurityModeComplete message to configure security with the UE, and when the security configuration is completed, the gNB may transmit an RRCConnectionReconfiguration message to the UE.

The gNB may allocate a bearer identifier (e.g., SRB identifier or DRB identifier) to each bearer by using an RRCConnectionReconfiguration message and may indicate PDCP layer configuration, RLC layer configuration, MAC layer configuration, and PHY layer configuration for each bearer. In addition, the gNB may configure a length (e.g., 12 bits or 18 bits) of a PDCP sequence number used in the PDCP layer for each bearer, and may configure a length (e.g., 6 bits, 12 bits or 18 bits) of an RLC sequence number used in the RLC layer in the RRCConnectionReconfiguration message. Further, the gNB may indicate whether a header compression and decompression protocol is used for each bearer in uplink or downlink of the PDCP layer, and may indicate whether to perform an integrity protection or authentication procedure in the RRCConnectionSetup message. Further, the gNB may indicate whether to perform an out-of-order delivery function in the PDCP layer.

Also, the RRCConnectionReconfiguration message may include configuration information of a DRB to process user data. In operation 1e-45, the UE may configure the DRB by applying the information, and may transmit an rrcconnectionreconfigureconcomplete message to the gNB.

In operation 1e-50, the gNB completing the DRB configuration with the UE may send an INITIAL CONTEXT SETUP COMPLETE message to the AMF or MME, and may COMPLETE the connection.

When the above procedure is completed, the UE may transmit/receive data to/from the gNB through the core network. According to some embodiments of the present disclosure, the data transmission procedure substantially includes three steps of RRC connection configuration, security configuration, and DRB configuration.

Further, in operations 1e-65, for some reason, the gNB may send an RRCConnectionReconfiguration message to the UE to newly add or change the configuration. The gNB may configure frequency configuration information of frequencies to be measured by the UE (e.g., a list of frequencies to be measured, a duration for measuring the frequencies, a condition for measuring and reporting the frequencies, and a cell identifier for reporting the frequencies) by using the RRCConnectionReconfiguration message.

The UE may perform frequency measurement according to the frequency measurement configuration information. In operations 1e-60, the UE may report a frequency measurement result to the gNB when a specific condition is satisfied (e.g., when the strength of a signal of a specific frequency is greater than a given value (e.g., a threshold), or when the strength of a signal of a current serving cell (frequency) is less than a given value (e.g., a threshold)).

In operations 1e-65, when the gNB receives the frequency measurement result, the gNB may cause Scell configuration information to be included in an rrcreeconfiguration (RRC reconfiguration) message based on the frequency measurement result, may transmit the rrcreeconfiguration message to the UE, may configure an additional Scell, and may configure carrier aggregation in the UE. Further, the gNB may cause secondary cell group configuration information to be included in the rrcreeconfiguration message, may transmit the rrcreeconfiguration message to the UE, and may configure dual connectivity in the UE. When the gNB configures carrier aggregation in the UE, the gNB may transition the configured Scell to an active or inactive or idle state by using a MAC Control Element (CE) in operations 1e-70 to 1 e-75.

According to an embodiment of the present disclosure, a procedure of the gNB configuring carrier aggregation or dual connectivity in the UE may be summarized as follows. First, when the UE configures a connection to the gNB and the gNB configures frequency measurement configuration information in the RRC connected mode UE, the UE may perform frequency measurement based on the frequency measurement configuration information and may report the measurement result to the gNB. The gNB may configure configuration information for additional scells in an RRC message to configure carrier aggregation in the UE based on frequency measurement results of the UE, and may activate, idle, or deactivate the Scell by transmitting the MAC CE. Further, the gNB may configure additional cell group configuration information based on the frequency measurement results of the UE to configure dual connectivity in the UE.

When the gNB configures carrier aggregation or dual connectivity in the UE as described above, if the UE first enters an RRC connected mode, receives frequency configuration information, performs frequency measurement, and needs to report the frequency measurement, measurement reporting may be performed very late, and carrier aggregation or dual connectivity may be configured very late. Therefore, to solve this problem, embodiments of the present disclosure may enable a UE to efficiently perform frequency measurement in an RRC idle mode or an RRC inactive mode and report the frequency measurement result once a network connection is configured.

Fig. 1F is a diagram for describing a method in which a UE performs early frequency measurement and makes a fast frequency measurement result report in a next generation mobile communication system according to an embodiment of the present disclosure.

In particular, referring to fig. 1F, a UE according to an embodiment of the present disclosure may perform early frequency measurement in an RRC idle mode or an RRC inactive mode and may make a fast frequency measurement result report.

In the first embodiment of the present disclosure, when the gNB configures frequency measurement configuration information for enabling the UE to perform frequency measurement in the RRC idle mode or the RRC inactive mode through the rrcreelease message in the UE, the gNB may configure a plurality of frequency measurement groups, and the UE may perform frequency measurement in the RRC idle mode or the RRC inactive mode.

Further, embodiments of the present disclosure may provide a method in which when the gNB indicates frequency measurement configuration information to an RRC inactive mode or RRC idle mode UE, the gNB may configure a separate frequency measurement list or a separate timer according to a frequency configuration group or a radio access technology (or for each cell or each beam). That is, embodiments of the present disclosure may provide a method in which a separate timer may be configured according to each frequency configuration group, and a separate duration may be configured according to each frequency configuration group by configuring a duration or timer value for which frequency measurement is to be performed for an LTE frequency (for each frequency or each cell), and configuring a duration or timer value for which frequency measurement is to be performed for an NR frequency (for each frequency, each cell, or each beam). ) That is, according to an embodiment of the present disclosure, a timer may be run for each frequency group, and frequency measurement may be performed until the timer expires. While a separate timer may be configured for each radio access technology, each cell, or each cell beam, the frequency measurement duration may vary according to frequency characteristics, beam characteristics, or cell characteristics, thereby optimizing the battery consumption of the UE.

In the first embodiment of the present disclosure, a UE capable of performing frequency measurement in an RRC idle mode or an RRC inactive mode and making a fast frequency measurement result report may correspond to one or more of the following UEs.

1. All UEs having the capability to support methods of performing early frequency measurements and fast frequency measurement result reporting in RRC idle mode or RRC inactive mode

2. A UE belonging to an RRC idle mode or an inactive mode UE and receiving configuration information indicating that frequency measurement is performed in the RRC idle mode or the RRC inactive mode when the UE is transitioned from an RRC connected mode to the RRC idle mode or the RRC inactive mode by the gNB through an RRC message. For example, a UE configured with frequency configuration information for performing frequency measurements in an RRC idle mode or an RRC inactive mode, a measurement duration (e.g., a timer value), or area configuration information (e.g., a list of cell identifiers) for performing frequency measurements

Referring to fig. 1F, in operation 1F-05, a UE in RRC connected mode may transition from the gNB to an RRC idle mode or an RRC inactive mode for some reason (e.g., no data transmission/reception for a certain period of time).

In operations 1f-10, the gNB may send an RRC message when the gNB switches the mode of the UE. For example, the gNB may send a RRCRelease message (indicating a transition to RRC idle mode) or a RRCRelease message (indicating a transition to RRC inactive mode) including suspend-config. When the UE performs fast (early) frequency measurement in the RRC idle mode or the RRC inactive mode, the RRC message may include the following information or some information to be applied.

-frequency configuration information of frequencies to be measured in RRC idle mode or RRC inactive mode

1. Frequency configuration information

LTE frequency measurement information set or list (evolved Universal terrestrial radio Access (EUTRA) frequency configuration information/list/set)

An lte frequency measurement information group or list may include frequency measurement configuration information (early measurement settings), such as which frequencies or which frequency bands to measure (e.g., a frequency list), which order to use to perform measurement by configuring a priority of each frequency, which filtering method to use to measure the strength of a frequency when measuring a frequency (e.g., L1 filtering, L2 filtering, L3 filtering methods, or a calculation method using coefficients), which event or condition to initiate measurement when measuring a frequency, which criterion (e.g., when signal strength is equal to or greater than an indicated threshold) to perform and report measurement as compared to a current serving cell (or a currently camped frequency), which event or condition to report a measured frequency result, which criterion or condition to satisfy to report a frequency as compared to a current serving cell (or a currently camped frequency), or which period will be used to report frequency measurements.

NR frequency measurement information set or list (NR frequency configuration information/list/set)

The nr frequency measurement information group or list may include frequency measurement configuration information (early measurement settings), such as which frequencies or which frequency bands (e.g., a frequency list) are to be measured, which order is to be used to perform the measurement by configuring the priority of each frequency (each Synchronization Signal Block (SSB)), SSB transmission resources (frequency and time resources, beam identifiers or beam indicators) or SSB identifier information of each frequency, which filtering method is used to measure the strength of the frequency when measuring the frequency (e.g., L1 filtering, L2 filtering, L3 filtering method, or a calculation method using coefficients), which event or condition is used to initiate the measurement when measuring the frequency, which criterion (e.g., when the strength of the signal is equal to or greater than an indicated threshold) is used to perform and report the measurement compared to the current serving cell (or the frequency currently camped on), which event or condition is to be used for reporting the measured frequency result, which criterion or condition is to be met for reporting the frequency compared to the current serving cell (or the current camped frequency), or which period is to be used for reporting the frequency measurement result.

2. A timer value (e.g., T331) for performing frequency measurement or a duration for performing frequency measurement in an RRC idle mode or an RRC inactive mode, or a timer for an LTE frequency and a timer for an NR frequency may be separately configured. Since the LTE frequency characteristics (low frequency band) and the NR frequency characteristics (high frequency band) are different from each other, it is possible to save battery power of the UE by adjusting the frequency measurement time of the UE individually. For example, when it is indicated in rrcreelease that the frequency is measured in the RRC idle mode or the RRC inactive mode, the frequency measurement may be performed when the timer starts and runs, and the frequency measurement may be stopped when the timer expires.

3. Validity region information for performing frequency measurement in an RRC idle mode or an RRC inactive mode. For example, when a list of Physical Cell Identifiers (PCIDs) is indicated and the UE is in a cell indicated in the validity area information, frequency measurement may be performed, and when the UE is outside the validity area information, frequency measurement may be stopped. For example, when the UE is outside the validity area information, the timer may be stopped and the frequency measurement may be stopped. Also, in another method, when the UE transitions to the RRC inactive mode, the gNB may determine whether to use the RAN notification area as the validity area by using the indicator. For example, when the gNB indicates to the UE transitioning to the RRC inactive mode to use the RAN notification area as the validity area through the indicator, the UE may perform frequency measurement within the RAN notification area while maintaining the RRC inactive mode within the RAN notification area. In another approach, the gNB may indicate, via an indicator, that the validity region is to be used as a RAN notification region. In another approach, the UE may operate by treating the RAN notification area as a validity area even when there is no indicator in the RRC inactive mode, and the gNB may configure a separate validity area in the UE in the RRC active mode. Since the RAN notification area and the validity area are both indicated by using the cell identifier list in the RRC message, signaling overhead can be reduced by the above method, and since the UE does not need to separately manage the validity area, a burden on the UE can be reduced.

4. A measurement reporting threshold may be configured and a plurality of frequencies having a greater signal strength than the threshold in the configured set of frequencies may be reported.

Further, the gNB may define and configure a value of the second timer in the rrcreelease message and may indicate how long the frequency measurement result value measured by the UE is valid. For example, for a second timer that runs based on the value of the second timer, the UE may store and use the timer value when receiving the rrcreelease message. The second timer may be started when the UE receives the rrcreelease message, and when the second timer expires, the UE may determine that the measured frequency measurement is invalid and may discard the measured frequency measurement. That is, the UE may not report to the gNB. In another approach, the second timer may be started when the first timer expires or stops. This is because, since the frequency measurement result can be updated while the frequency measurement is performed, the valid duration of the latest frequency measurement result can be indicated by starting the second timer from the point of time at which the first timer expires or stops to stop the frequency measurement. When the second timer expires, the UE may determine that the measured frequency measurement is invalid and may discard the measured frequency measurement. That is, the UE may not report to the gNB. In another approach, the UE or the gNB may define and use the first timer to perform the function of the second timer.

When receiving the rrcreelease message and including the fast frequency measurement configuration information, the UE may release or discard the stored frequency measurement configuration information or frequency measurement result, and may perform frequency measurement by storing, updating, and applying the new fast frequency measurement configuration information. In another method, when only a frequency measurement duration or timer value is configured in the fast frequency measurement configuration information, the UE may restart the timer based on the value and may continue the frequency measurement configuration while maintaining the existing frequency configuration information. Alternatively, the UE may start a timer based on the value, may release existing frequency configuration information, may receive system information in a camped cell through a cell reselection procedure, and may perform frequency measurement by applying the frequency configuration information when the frequency configuration information exists. In another approach, the gNB may define a new indicator in the rrcreelease message and may indicate whether to continue frequency measurement, stop frequency measurement, or release frequency measurement configuration information by using existing frequency measurement configuration information. In another method, the UE may release the existing frequency configuration information only when the frequency measurement configuration information is included in the rrcreelease message, and may maintain and apply the existing frequency configuration information when there is no frequency configuration information.

In operation 1f-30, when the UE performs early frequency measurement in the RRC idle mode or the RRC inactive mode, the condition for initiating frequency measurement may satisfy at least one of the following conditions.

1. When the UE receives the rrcreelease message, includes an indicator for performing frequency measurement in the RRC idle mode or the RRC inactive mode, and configures a duration (e.g., a timer value) for measuring a frequency and frequency information of a frequency to be measured, the UE may start a timer and may perform frequency measurement according to the frequency information.

2. When the UE receives the rrcreelease message, includes an indicator for performing frequency measurement in the RRC idle mode or the RRC inactive mode, and configures a duration (e.g., a timer value) for measuring a frequency, but does not include frequency information of the frequency to be measured, the UE may start a timer, and when the frequency information of the frequency to be measured in the RRC idle mode or the RRC inactive mode is broadcast in the system information, the UE may perform the frequency measurement according to the frequency information. When the UE can move to another cell, if frequency information of a frequency to be measured in the RRC idle mode or the RRC inactive mode is broadcast in system information of a newly camped cell, the UE can perform frequency measurement according to the new frequency information.

That is, when frequency measurement configuration information for performing frequency measurement in the RRC idle mode or the RRC inactive mode is not configured in the rrcreelease message, if the frequency configuration information for the RRC idle mode or the RRC inactive mode frequency measurement is broadcast in the system information, the UE may perform the frequency measurement in the RRC idle mode or the RRC inactive mode based on the frequency configuration information.

Referring to operations 1f-12, when the UE moves and camps on a new cell, the UE may update the frequency measurement information to frequency configuration information for RRC idle mode or RRC inactive mode frequency measurement broadcast in the new cell, and may perform the frequency measurement again.

However, when frequency measurement configuration information for performing frequency measurement in the RRC idle mode or the RRC inactive mode is configured in the rrcreelease message, the UE may perform frequency measurement by preferentially applying the frequency measurement configuration information configured in the rrcrese message to the RRC idle mode or the RRC inactive mode frequency measurement information broadcasted in the system information. That is, when frequency measurement configuration information for performing frequency measurement in the RRC idle mode or the RRC inactive mode is configured in the rrcreelease message, the UE may not reflect or consider the frequency measurement configuration information broadcasted in the system information, or may discard the frequency measurement configuration information.

As described above, the UE may start fast (early) frequency measurements according to at least one of the above conditions. In operations 1f-35, the UE may send a message 3(RRCSetupRequest or RRCResumeRequest (RRC recovery request)) to the gNB while performing frequency measurements. In operations 1f-40, the UE may receive a message 4 (e.g., RRCSetup or rrcresum (RRC recovery)) from the gNB in response to message 3 and may determine that the random access procedure has succeeded. In operation 1f-45, the UE may transition to RRC connected mode.

When an indicator indicating that RRC idle mode or RRC inactive mode frequency measurement is supported or an indicator indicating that RRC idle mode or RRC inactive mode frequency measurement results may be received is broadcast in received system information (e.g., SIB2) before configuring a connection in the current cell, the UE may inform the gNB through the indicator that there are frequency measurement results measured in the RRC idle mode or RRC inactive mode in message 5 (e.g., RRC setup complete or RRC resume complete).

In operation 1f-50, when the UE transmits a message 5 (e.g., RRCSetupComplete or RRCResumeComplete), the UE may cause an indicator indicating that early frequency measurement has been performed in an RRC idle mode or an RRC inactive mode and that there is a frequency measurement result to be reported to be included in the message 5, and may transmit the message 5. In message 5, a new indicator may be defined in message 5 to indicate that there is a fast frequency measurement result, or an indicator indicating that there is previously defined UE information in an RRC message (RRCSetupComplete or RRCResumeComplete) may be reused. In another method, in the system information, an indicator may be defined and used as an indicator indicating LTE frequency measurement support or NR frequency measurement support. Further, when the message 5 indicates that there is a frequency measurement result measured in the RRC idle mode or the RRC inactive mode, an indicator of a measurement result of an LTE frequency and an indicator of a measurement result of an NR frequency may be defined and indicated, respectively.

In operations 1f-55, when the gNB determines through the indicator in message 5 that the UE has performed early frequency measurement in the RRC idle mode or the RRC inactive mode and there is a measurement result to report, the gNB may send a message to the UE to report the measurement result in order to quickly receive a frequency measurement result report. For example, the gNB may request frequency measurement result information from the UE by newly defining and using a UE information request message as a DL Dedicated Control Channel (DCCH) message.

In operations 1f-65, when the UE receives the message, the UE may quickly report fast (early) frequency measurement results to the gNB. For example, when the UE receives the message, the UE may report the frequency measurement result by newly defining and using a UE information response message as a UL-DCCH message. The frequency measurement results may include serving cell/frequency measurement results (e.g., NR-SS reference signal received power/reference signal received quality (RSRP/RSRQ)), serving cell/frequency neighbor cell/frequency measurement results, and cell/frequency measurement results indicating to be measured, which may be measured by the UE. In another method, the gNB may request frequency measurement result information from the UE by defining and using an indicator in the rrcreeconfiguration message. When the UE receives the message, the UE may quickly report the early frequency measurement (early measurement) result to the gNB. For example, when the UE receives the message, the UE may report the frequency measurement result by using a rrcreeconfigurationcomplete message, and in another method, the UE may report the frequency measurement result by defining and using a new field for reporting the frequency measurement result in a UL-DCCH message.

The condition for the UE to stop the early frequency measurement in the RRC idle mode or the inactive mode may include at least one of the following conditions.

1. After notifying the gNB that the system information of the current cell supports fast frequency measurement result reporting and that there is a measurement result report in an RRC message (e.g., message 5), or when notifying the gNB that the system information of the current cell supports fast frequency measurement result reporting and that there is a measurement result report in an RRC message (e.g., message 5)

2. When the UE configures network connection while performing RRC idle mode or RRCinamive mode frequency measurement, when a timer is stopped and measurement is stopped upon receiving a RRCSetup message or a RRCRESUME message as a message 4, and when system information informing the gNB that the current cell supports fast frequency measurement result reporting and there is a measurement result report in an RRC message (e.g., a message 5)

3. When a measurement report timer (e.g., T331) expires

4. When the UE is outside the area indicated by the RRC idle mode or RRC inactive mode frequency measurement area information configured in the RRCRelease message

In operation 1f-60, the UE may stop RRC idle mode or RRC inactive mode frequency measurements (idle mode/inactive mode measurements) according to at least one of the above conditions.

The UE may perform measurement on frequencies that the UE can measure (i.e., frequencies supported in the fast frequency configuration-related information), and in this case, the UE may select frequencies to be preferentially measured according to the configured priority.

As described below, embodiments of the present disclosure may provide detailed UE operations reporting the frequency measurement result of the first embodiment, in which the UE performs and reports early frequency measurement in an RRC idle mode or an RRC inactive mode.

Upon reception of the RRCSetup message or rrcreesume message as message 4, the UE may perform the following operations.

1. When system information (e.g., SIB2) broadcasts or includes an indicator (idle or inactive mode measurement) indicating that RRC idle mode or RRC inactive mode frequency measurement can be supported, and the UE has a frequency measurement result measured in RRC idle mode or RRC inactive mode,

the ue may cause an indicator (idle or inactive Measavailable) indicating that there is an RRC idle mode or RRC inactive mode frequency measurement result to be included as message 5 in the RRCSetupComplete message or RRCResumeComplete message. Thus, the UE may indicate that there is RRC idle mode or RRC inactive mode frequency measurement information to report to the gNB through the message.

B. Because the frequency measurement result is to be reported, the UE may stop the timer (e.g., T331) for the RRC idle mode or RRC inactive mode frequency measurement. The UE may stop the frequency measurement and may discard the frequency measurement configuration information.

Fig. 1H is a diagram for describing a method in which a UE performs early frequency measurement and makes a fast frequency measurement result report in a next generation mobile communication system according to an embodiment of the present disclosure. Specifically, fig. 1H is a diagram illustrating a second embodiment, in which a UE may perform early frequency measurements (early measurements) and may make fast frequency measurement result reports (fast measurement reports) in an RRC idle mode or an RRC inactive mode.

The description of the first embodiment is applicable to the second embodiment of the present disclosure. Further, when the gNB configures frequency measurement configuration information for enabling the UE to perform frequency measurement in the RRC idle mode or the RRC inactive mode through an rrcreelease message in the UE, the gNB may configure a plurality of frequency measurement groups. In the method of the present embodiment of the present disclosure, the UE may perform frequency measurement in an RRC idle mode or an RRC inactive mode, and may transmit a message 3 to the gNB when configuring network connection, the gNB may perform measurement report indication in a message 4 (e.g., rrcresum) when transmitting the message 4 in response to the message 3, and may make a frequency measurement result report ((e.g., rrcresum complete)) in a message 5. Therefore, frequency measurement result reporting can be made quickly compared to the first embodiment, and measurement results after increasing the security level can be reported. This is because the RRC inactive mode UE activates the security algorithm of the SRB1 from the time point when the message 3 is transmitted. That is, the messages 4 and 5 may be ciphered and integrity-protected with a new security key in the PDCP layer and may be transmitted.

In the RRC idle mode or the RRC inactive mode, the UE may perform frequency measurement, may store the measurement result, may perform random access, and may then transmit a message 3 (e.g., a RRCSetupRequest or a RRCResumeRequest). When the gNB sends message 4 (e.g., RRCSetup or rrcresum) to the UE, the gNB may cause an indicator to report the frequency measurement result to be included in message 4 and may send message 4. In another approach, the indicator may be omitted because the message 4 itself may indicate that the UE is to report frequency measurements.

The UE may report the frequency measurement in message 5 (e.g., RRCSetupcomplete or RRCRESUMeComplete) (. because the RRC inactive mode UE may resume or activate the security procedures (encryption and decryption or integrity protection and verification) of the signaling radio bearer SRB1 when sending the RRCRESUMRequest message, the RRC inactive mode UE may increase the security level and receive message 4 when receiving message 4 and may increase the security level and report the frequency measurement of message 5 when reporting the frequency measurement of message 5. further, the gNB may cause carrier aggregation configuration or dual connectivity configuration information to be included in the RRC message by using the above information and may send the RRC message so that the UE may quickly restart, change, or reconfigure carrier aggregation or dual connectivity.

Referring to fig. 1H, the RRC connected mode UE may receive frequency measurement configuration information from the gNB and an indication to release RRC connection and transition to RRC idle mode or RRC inactive mode. In this case, the UE may perform frequency measurements for a configured duration or time in an RRC idle mode or an RRC inactive mode. However, when there is no information on the list of frequencies to be measured in the frequency measurement configuration information, if frequency measurement configuration information for frequency measurement of an RRC idle mode or RRC inactive mode UE is broadcast in the camped cell and a cell reselection procedure is simultaneously performed, the UE may receive the information and may perform the frequency measurement.

When the UE receives the rrcreelease message and transitions to the RRC inactive mode, in order to effectively process a secondary cell (Scell) configured for carrier aggregation and a Secondary Cell Group (SCG) configured for dual connectivity, the UE may perform at least one of the following methods.

Method 1 the UE may release the SCell configuration information and the SCG configuration information. When configuring a connection later, the gNB may quickly configure information on the Scell for carrier aggregation or the SCG for dual connection in the UE through a rrcresum message or a rrcreconfigration message based on the quick frequency measurement result report. According to method 1, it may be advantageous when considering memory because the UE does not need to maintain configuration information of scells or configuration information of SCGs, and implementation may be facilitated because the gNB does not need to retrieve existing configuration information of scells or SCGs from the source gNB.

Method 2, the UE may store the configuration information of the SCell or the configuration information of the SCG, and may suspend the bearer configuration or transmission of the SCell or the SCG. When configuring a connection later, the gNB allows the UE to reuse information on the Scell for carrier aggregation or the SCG for dual connectivity through a rrcresum message or a rrcreeconfiguration message reported based on a fast frequency measurement result, may update only some configuration information (delta configuration), or may perform completely new configuration. According to method 2, since the UE maintains the configuration information of the SCell or the configuration information of the SCG, the gNB may use the existing configuration information of the SCell or the SCG, thereby reducing signaling overhead. Further, the UE may quickly apply and initiate carrier aggregation or dual connectivity. Even when the RRC inactive mode UE resumes the connection, the configuration information for the SCell or the configuration information for the CG may not be released or discarded, and the gNB may indicate to maintain or discard the configuration information for the SCell or the configuration information for the SCG by defining an indicator in the rrcreesume message. In another approach, the gNB may indicate to maintain or discard configuration information for the Scell or configuration information for the SCG by using a full configuration information indicator (fullConfig). In another approach, when the gNB sends a rrcreelease message to the UE to transition the RRC connected mode UE to an RRC inactive mode, the gNB may instruct that the SCell (master cell group (MCG) or SCG configuration information be maintained or discarded in the rrcreelease message. Accordingly, the UE may maintain the Scell or SCG configuration information according to the indicator of the rrcreelease message, may maintain the Scell or SCG configuration information even when the RRC connection recovery procedure is initiated, and may apply the configuration information according to the indication (e.g., RRC message) of the gNB. For example, the UE may release SCell or SCG configuration information when there is no indication of SCell or SCG configuration information in the rrcreelease message. When there is an indicator to maintain, store or discard the MCG SCell configuration information or the SCG PSCell or SCell configuration information, the UE may store and maintain the configuration information accordingly, may apply the configuration information even during RRC connection recovery, and may apply the configuration according to the indication of the gNB (RRC message). The configuration information for the Scell or the configuration information for the SCG may refer to PDCP layer configuration information, SDAP layer configuration information, RLC layer information, MAC layer information, or PHY layer configuration information, and may indicate part or all of these information. In another approach, since the RRC inactive mode UE moves when performing the RAN notification area update procedure, maintaining or discarding the Scell or SCG configuration information may be indicated in a rrcreelease message received in the RAN notification area update procedure. This is because the gNB may receive the context of the resume identifier when performing the RAN notification area update procedure, and thus may detect the UE configuration information. In another approach, when an RRC inactive UE performs an RRC connection recovery procedure with the gNB, if for some reason (e.g., fails to retrieve the UE context) the UE sends an RRCResumeRequest message but the gNB indicates fallback in the response to the RRCSetup message, the UE may discard the configuration information for the Scell or the configuration information for the SCG. This is because the gNB may not retrieve the UE context, and thus the gNB may not determine the configuration information for the Scell or the configuration information for the SCG stored in the UE. The configuration information for the Scell or the configuration information for the SCG may refer to PDCP layer configuration information, SDAP layer configuration information, RLC layer information, MAC layer information, or PHY layer configuration information, and may indicate some or all of these information. The gNB may use the existing SCell information or SCG information stored in the UE through an rrcresum message or an rrcreeconfiguration message in an RRC connection recovery procedure, and apply the above method, thereby rapidly configuring carrier aggregation or dual connectivity in the UE. When dual connectivity is configured, the gNB may result in including preamble information and frequency information required for random access SCG, and may notify the UE of the preamble information and the frequency information. Further, the gNB may indicate activation of the Scell or SCG in the rrcreesume message or rrcreeconfiguration message, and may also indicate fast channel measurement information (short Channel State Information (CSI) report or aperiodic CSI report).

When RRC connection configuration to the network is required, the UE may indicate that there is a result of frequency measurement in RRC idle mode or RRC inactive mode when configuring connection to the gNB.

When reconfiguring a network connection in an RRC idle mode or an RRC inactive mode, the UE may prepare a frequency measurement result if the UE supports early reporting of the frequency measurement result in a cell for configuring a current connection. Referring to operation 1h-35, the UE may perform random access as in operations 1h-20 to 1h-25, and may then send message 3 (e.g., a RRCSetupRequest or a RRCResumeRequest) to the gNB.

In operations 1h-40, the gNB may cause an indicator to report frequency measurements to be included in message 4 (e.g., RRCSetup or rrcresum) in order to quickly configure carrier aggregation or dual connectivity, and may send message 4 to the UE. In this case, in another approach, the indicator may be omitted because the message 4 sent by the gNB may itself indicate that frequency measurements are to be reported.

In operation 1h-50, when the UE receives message 4, the UE may simultaneously transmit and report a frequency measurement result (and message 5 (e.g., RRCSetupComplete or RRCResumeComplete) — network connection configuration may be performed, and when the gNB transmits message 4 (e.g., RRCSetup or RRCResume) or rrcrecconfiguration message to the UE, the gNB may cause carrier aggregation configuration information or dual connectivity configuration information to be included in the message 4 or rrcrecconfiguration message, so that the UE may quickly restart, change, or newly configure carrier aggregation or dual connectivity. And information on the frequency, Scell, or SCG satisfying a given condition may be reported in the RRCResumeComplete message. Alternatively, the UE may directly perform connection by performing a random access procedure for a frequency, Scell, or SCG satisfying a given condition. When the connection to the gbb or cell to which the UE is connected is complete, the gbb may inform the source gbb that the UE is already connected. The source gNB may request a plurality of different target gnbss for connection authorization and each target gNB may determine that the connection failed when the timer runs and the UE has no access for a certain period of time, or the source gNB may indicate that the UE configures a connection to another target gNB or may directly indicate to cancel the connection authorization.

1. After notifying the gNB of the fast frequency measurement result report in the system information support message 3 of the current cell, or when notifying the gNB of the fast frequency measurement result report in the system information support message 3 of the current cell

2. When the UE receives a frequency measurement result reporting indication in message 4 in a random access procedure for configuring network connection while performing RRC idle mode or RRC inactive mode frequency measurement, stops the timer and stops the measurement, and notifies the gbb that system information of the current cell supports fast frequency measurement result reporting and that there is a measurement result reporting in an RRC message (e.g., message 5)

3. When a measurement report is to be made by message 5

4. When a measurement report timer (e.g., T331) expires

5. When the UE is outside the area indicated by the RRC idle mode or RRC inactive mode frequency measurement area information configured in the RRCRelease message

The UE may stop RRC idle mode or RRC inactive mode frequency measurements (idle mode/inactive mode measurements) according to at least one of the above conditions.

In an embodiment of the present disclosure, the UE may perform measurement on frequencies measurable by the UE (i.e., frequencies supported in the fast frequency configuration-related information), and in this case, the UE may select frequencies to be preferentially measured according to the configured priority.

According to a second method of a method of quickly performing and reporting frequency measurement in an RRC idle mode or an RRC inactive mode, detailed UE operations that can provide reporting frequency measurement results can be provided as follows.

Upon receiving the random access response and receiving message 4 from the gNB, the UE may perform the following operations.

1. When system information (e.g., SIB2) broadcasts or includes an indicator (idle or inactive mode measurement) indicating that RRC idle mode or RRC inactive mode frequency measurement can be supported, and the UE has a frequency measurement result measured in the RRC idle mode or RRC inactive mode

The ue may cause the RRC idle mode or RRC inactive mode frequency measurement result to be included in message 5 (RRCSetupRequest message or rrcresumererequest message). In another method, the UE may multiplex an RRC message (e.g., message 5) and a frequency measurement result in the MAC layer and may transmit the RRC message and the frequency measurement result. Accordingly, the UE may report RRC idle mode or RRC inactive mode frequency measurement information to the gNB through the message.

B. Because the frequency measurement result is to be reported, the UE may stop the timer (e.g., T331) for the RRC idle mode or RRC inactive mode frequency measurement. The UE may stop the frequency measurement and may discard the frequency measurement configuration information and the frequency measurement result.

Embodiments of the present disclosure may provide an efficient signaling method in which a network or a gNB may more efficiently configure or update frequency measurement configuration information in a UE having mobility in an RRC deactivation mode.

The most significant difference between RRC idle mode UEs and RRC deactivated mode UEs is that RRC deactivated mode UEs can store UE context in the gNB and UE and can quickly configure connections by reusing UE context, and RRC deactivated mode UEs can update the area where RRC deactivated mode must be maintained from the network by periodically updating RAN notification area.

According to an embodiment of the present disclosure, when an RRC connected mode UE receives frequency measurement configuration information and an indication to release an RRC connection from a gNB and transition to an RRC deactivated mode, the UE may perform frequency measurements for a configured duration or time in the RRC deactivated mode. When the RRC deactivation mode UE moves out of the configured RAN notification area, the RRC deactivation mode UE may configure a connection to the network to perform a RAN Notification Area Update (RNAU) procedure. In this case, for a UE performing a connection to the network to update the RAN notification area, the gNB may configure or update a new frequency measurement configuration, or may instruct the UE to maintain the frequency measurement, according to an embodiment of the present disclosure.

In detail, the present disclosure may provide two procedures for updating the RAN notification area.

Fig. 1I is a schematic diagram for describing a RAN notification area update procedure according to an embodiment of the present disclosure.

In operations 1i-20, when the RRC deactivation mode UE moves out of the RAN notification area, the RRC deactivation mode UE may perform a random access procedure to perform a RAN notification area update procedure, and may send a message 3 (e.g., RRCResumeRequest) to the gNB to connect to the network.

The gNB may identify a connection restoration identifier of the UE in message 3 to retrieve the UE context from the source gNB, and may identify a connection restoration cause in message 3 to determine that the UE needs to update the RAN notification area.

In operations 1i-25, the gNB may send a message 4 (e.g., rrcresum (RRC recovery)) to the UE to update the RAN notification area so that the UE may transition to RRC connected mode.

In operations 1i-35, the UE may send message 5 and may indicate that the connection has been properly established. In operations 1i-40, the gNB may cause a new RAN notification area to be included in a rrcreelease (RRC release) message to update the RAN notification area, may send the rrcreelease message to the UE, and may instruct the UE to re-transition to the RRC deactivated mode. When the UE receives the rrcreelease message, the UE may identify and reflect new RAN notification area information, may maintain mobility, and may transition to an RRC deactivation mode.

Fig. 1J is a schematic diagram for describing a RAN notification area update procedure according to an embodiment of the present disclosure.

In operations 1j-20, when the RRC deactivation mode UE moves out of the RAN notification area, the RRC deactivation mode UE may perform a random access procedure to perform a RAN notification area update procedure, and may send a message 3 (e.g., RRCResumeRequest) to the gNB to perform a connection to the network.

In operations 1j-40, the gNB may cause a new RAN notification area to be included in a rrcreelease message to update the RAN notification area, may send the rrcreelease message to the UE, and may instruct the UE to maintain the RRC deactivation mode. When the UE receives the rrcreelease message, the UE may identify and reflect new RAN notification area information, may maintain mobility, and may maintain an RRC deactivation mode. The RAN notification area update procedure may reduce signaling overhead and may not require state transition of the UE when compared to the RAN notification area update method of fig. 1I. That is, the UE may perform the RAN notification area update procedure while maintaining the RRC deactivation mode.

In the RAN notification area update procedure described above, the gNB may retrieve the UE context from the source gNB through the connection recovery identifier indicated by the UE in message 3(RRC recovery request), and may determine whether the UE is to perform frequency measurement configuration in the RRC deactivated mode. Further, the UE may indicate that the connection recovery reason (resumecuse) is the RAN notification area in the update message 3. In another method, when the UE transmits message 3 to update the RAN notification area, the UE may cause an indicator indicating that frequency measurement is performed in the RRC deactivation mode, that timer T331 expires or is running, or new frequency configuration information needs to be included in message 3, and may transmit message 3 to the gNB to indicate the information to the gNB.

As described with reference to operations 1i-40 and 1j-40, when the gNB determines whether the UE can perform frequency measurement in the RRC deactivation mode and then transmits an RRC message (e.g., an rrcreelease message) including information for updating the RAN notification area to the UE, the gNB may cause new frequency measurement configuration information to be included in the RRC message and may transmit and configure the RRC message. The new frequency measurement configuration information may include configuration information such as a list of frequencies to measure, a list of physical cell identifiers, or a measurement duration, or a validity area for measurement (e.g., a list of cell identifiers). Accordingly, when an RRC deactivation mode UE moves and passes coverage supported by another cell or a gNB, the UE and the gNB according to an embodiment of the present disclosure may newly update or change frequency measurement configuration information in the RRC deactivation mode through a RAN notification area update procedure, the UE having mobility may quickly report the frequency measurement configuration information when configuring a connection to a network later, and may quickly configure dual connectivity or carrier aggregation.

Further, embodiments of the present disclosure may provide a procedure in which when a gNB or a cell to which the UE is connected may support RRC idle mode or deactivation mode frequency measurement, when information may indicate that RRC idle mode or deactivation mode frequency measurement is supported, and when a frequency measurement result may be reported to the gNB, the UE may stop the timer T331 for RRC idle mode or deactivation mode frequency measurement, and may discard or release the frequency measurement configuration information or discard the frequency measurement result.

Further, in an embodiment of the present disclosure, the RRC deactivation mode or RRC idle mode UE may configure a separate area (e.g., a validity area) for performing frequency measurement in the rrcreelease message. That is, the UE may perform frequency measurement in the RRC deactivation mode or the RRC idle mode only within the active area, and when outside the active area, the UE may stop the timer, may release the frequency measurement configuration information, may discard the frequency measurement result, or may stop the frequency measurement. The validity area may be defined by a list of physical cell identifiers

Or RAN notification area indicator list. Embodiments of the present disclosure may provide a method in

A method of configuring a validity area and a RAN announcement area, respectively, in an RRC deactivation mode UE, and a method of allowing the RRC deactivation mode UE to use the RAN announcement area instead of the validity area (or use the validity area instead of the RAN announcement area) by using an indicator, so as to reduce a burden on the UE and reduce signaling overhead. This is because when a separate validity area is indicated to the UE, the UE may have a burden of maintaining and updating a tracking area, maintaining and updating a RAN notification area, and maintaining and managing the validity area. That is, when the UE receives the rrcreelease message and receives information for transitioning the UE to the RRC deactivation mode, when frequency measurement configuration information and an indicator are present, or when it is indicated to use the RAN notification area, the UE may transition to the RRC deactivation mode and may perform frequency measurement by regarding the RAN notification area as a validity area. When the UE receives the rrcreelease message and receives information for transitioning the UE to the RRC deactivation mode, when there is frequency measurement configuration information and no indicator, when there is no indication to use the RAN notification area, or when a separate validity area is configured and indicated, the UE may transition to the RRC deactivation mode, may perform frequency measurement by considering the validity area, and may manage mobility of the RRC deactivation mode according to the RAN notification area.

Embodiments of the present disclosure may provide for efficient UE operation performed by a UE that is capable of measuring frequency measurements or is configured to perform frequency measurements in an RRC deactivated mode in RAN notification area update procedures (e.g., first and second RAN notification area update procedures).

-when the UE sends message 3 to perform a RAN notification area update procedure and receives a rrcreelease message in the first RAN notification area update procedure or the second RAN notification area update procedure

Or, when the UE receives the rrcreelease message

1. When the UE receives the rrcreelease message, including the frequency measurement configuration information, there is information on the frequency measurement duration, and there is no frequency measurement list information,

the ue may configure the frequency measurement time as a timer value and may drive a timer.

The ue may perform a frequency measurement procedure based on previously stored information (information indicated in a previous rrcreelease message or information indicated in last received system information). In another approach, the UE may determine that existing stored frequency measurement information is invalid information, may discard the existing stored frequency measurement information, may perform a cell reselection procedure, and may receive new frequency measurement information from the system information. When the UE receives the frequency measurement information, the UE may start frequency measurement.

2. When the rrcreelease message is received, including the frequency measurement configuration information, and there is information on the frequency measurement duration and frequency information of the frequency to be measured,

the ue may configure the frequency measurement duration as a timer value and may drive a timer.

The ue may determine that the existing stored information is invalid information, may discard the existing stored information, may receive new frequency measurement information included in the rrcreelease message, may store the new frequency measurement information, and may perform frequency measurement. The UE may resume frequency measurement when the frequency measurement stops, and may resume frequency measurement when the frequency measurement never stops.

-when the UE performs frequency measurement in the RRC deactivation mode, when the UE sends message 3 and receives a rrcreelease message to perform a RAN notification area update procedure, i.e. when the UE receives a rrcreelease message in a state where the RRC deactivation mode is maintained and no RRC mode state transition occurs

-furthermore, when the UE performs frequency measurements in RRC deactivated mode, when the UE sends message 3 and receives a rrcreelease message to perform a RAN notification area update procedure

1. When there is no new frequency measurement configuration information in the rrcreelease message,

The ue may continue to perform frequency measurements based on existing frequency configuration information.

2. When new frequency measurement configuration information exists in the rrcreelease message,

the ue may discard or release existing frequency measurement configuration information or frequency measurement results.

The ue may configure a duration or timer value included in the new frequency measurement configuration information and may initialize and drive the timer again.

C. When there is a frequency measurement list in the frequency measurement configuration information,

the ue may perform frequency measurements on the frequency measurement list.

D. When there is no frequency measurement list in the frequency measurement configuration information,

the UE may perform a cell reselection procedure, and when frequency measurement information exists in the system information of the camping cell, the UE may receive and store the frequency measurement information and may perform frequency measurement.

In another method, when the UE performs frequency measurement in the RRC deactivation mode, the UE may stop frequency measurement and may receive a rrcreelease message when the UE transmits a message 3 to perform a RAN notification area update procedure, and when there is no new frequency measurement information, the UE may resume frequency measurement based on the existing frequency measurement information. Further, when new frequency measurement information exists in the rrcreelease message, the UE may resume frequency measurement based on the new frequency measurement information.

In another method, when the rrcreelease message is received and includes the fast frequency measurement configuration information, the UE may release or discard the stored frequency measurement configuration information or frequency measurement result, and may perform frequency measurement by storing, updating, and applying the new fast frequency measurement configuration information. In another method, when only a frequency measurement duration of a timer value is configured in the fast frequency measurement configuration information, the UE may restart the timer based on the value and may continue the frequency measurement configuration while maintaining the existing frequency configuration information. Alternatively, the UE may start a timer based on the value, may release existing frequency configuration information, may receive system information in a camped cell through a cell reselection procedure, and may perform frequency measurement by applying the frequency configuration information when the frequency configuration information exists. In another approach, the gNB may define a new indicator in the rrcreelease message and may indicate whether to continue frequency measurement, stop frequency measurement, or release frequency measurement configuration information by using existing frequency measurement configuration information. In another method, the UE may release the existing frequency configuration information only when the frequency measurement configuration information is included in the rrcreelease message, and may maintain and apply the existing frequency configuration information when there is no frequency configuration information.

In another approach, the following embodiments of the present disclosure are possible.

301-when the UE sends message 3 to perform the RAN notification area update procedure, and receives the rrcreelease message in response to message 3 in the first RAN notification area update procedure or the second RAN notification area update procedure

Or, when the UE receives the rrcreelease message

1. When the UE receives the rrcreelease message, including frequency measurement configuration information, there is information on the frequency measurement duration and there is no frequency measurement list information, or when a new indicator is included to maintain frequency measurement information or frequency measurement results and to continue frequency measurement,

the ue may configure the frequency measurement duration as a timer value and may drive the timer again. Further, when the timer is running, the UE may stop the timer, may initialize the timer, may configure a value configured in the RRC message as a timer value, and may restart the timer again.

The ue may perform a frequency measurement procedure based on previously stored information (information indicated in a previous rrcreelease message or information indicated in last received system information). In another approach, the UE may determine that existing stored frequency measurement information or frequency measurements are invalid information, may discard the existing stored frequency measurement information or frequency measurements, may perform a cell reselection procedure, and may receive new frequency measurement information from the system information. When the UE receives the frequency measurement information, the UE may start frequency measurement.

2. When a rrcreelease message is received, including frequency measurement configuration information, and there is information on frequency measurement duration and frequency information of a frequency to be measured, or when an indicator holding frequency measurement information or frequency measurement results and continuing frequency measurement is included,

the ue may configure the frequency measurement duration as a timer value and may drive a timer. Further, when the timer is running, the UE may stop the timer, may initialize the timer, may configure a value configured in the RRC message as a timer value, and may restart the timer again.

The ue may determine that existing stored frequency measurement information or frequency measurement results are invalid information, may discard the existing stored frequency measurement information or frequency measurement results, and may perform frequency measurement by receiving and storing new frequency measurement information included in the rrcreelease message. The UE may resume frequency measurement when the frequency measurement stops, and may resume frequency measurement when the frequency measurement never stops.

3. When a rrcreelease message is received and there is no frequency measurement configuration information, when a new indicator to hold frequency measurement information or frequency measurement results and continue frequency measurement is not included, or when a new indicator to release or discard frequency measurement information or frequency measurement results and stop frequency measurement is not included,

The UE may determine that existing stored frequency measurement information or frequency measurement results are invalid information, and may discard the existing stored frequency measurement information or frequency measurement results, and when a timer for frequency measurement is running, the UE may stop the timer.

Embodiments of the present disclosure may provide a method of performing a frequency measurement operation when an RRC deactivated mode UE attempts to resume connection to a network and falls back to an RRC idle mode due to an indication of a gNB.

Fig. 1K is a schematic diagram for describing a procedure for an RRC deactivated UE to fall back to an RRC idle mode due to an indication of the gNB, according to an embodiment of the present disclosure. Referring to fig. 1K, a first embodiment of performing a frequency measurement operation when an RRC deactivation mode UE attempts to recover a connection to a network and falls back to an RRC idle mode due to an indication of a gNB is as follows.

The UE may send message 3 to perform a RAN notification area update procedure while performing frequency measurements in RRC deactivated mode, as in operation 1k-20, and the gNB may send a RRCSetup (RRC setup) message as message 4, as in operation 1 k-40. As in operation 1k-45, when the UE may need to cancel the connection recovery procedure or transition from RRC deactivated mode to RRC idle mode,

The UE may stop a timer for frequency measurement, may discard frequency measurement configuration information or frequency measurement results, and may stop frequency measurement. Further, the UE may discard the frequency measurement. That is, when the RRC deactivation mode UE falls back, implementation of the UE and the gNB may be facilitated by a method in which the UE discards and releases all previously configured information.

A second embodiment of performing a frequency measurement operation when an RRC deactivated mode UE attempts to resume connection to the network and falls back to RRC idle mode due to an indication of the gNB may be as follows.

As in operation 1k-20, the UE may send message 3 to perform the RAN notification area update procedure while performing frequency measurements in RRC deactivated mode. As in operations 1k-40, the gNB may send an RRCSetup message as message 4. As in operation 1k-45, when the UE may need to cancel the connection recovery procedure or transition from RRC deactivated mode to RRC idle mode,

1. as with the above-described embodiments of the present disclosure, the UE may indicate that there is a frequency measurement and may report the frequency measurement. That is, the UE may continue to use the measurement results efficiently. Whether the frequency measurement result is valid may be determined by the gNB. For example, the gNB may operate as follows.

A. When system information (e.g., SIB2) broadcasts or includes an indicator (idle or deactivated mode measurement) indicating that RRC idle mode or RRC deactivated mode frequency measurement can be supported, and the UE has a frequency measurement result measured in RRC idle mode or RRC deactivated mode,

the ue may cause an indicator indicating that the frequency measurement has been performed in the RRC idle mode or the RRC deactivated mode and include the frequency measurement result in message 5(RRC setup complete) in operation k 1-50. Thus, the UE may indicate that there is RRC idle mode or RRC deactivated mode frequency measurement information to report to the gNB through the above message.

The UE may stop the timer (e.g., T331) for RRC idle mode or RRC deactivated mode frequency measurements because the frequency measurement results are to be reported. The UE may stop the frequency measurement and may discard the frequency measurement configuration information or the frequency measurement result.

In the above-described embodiments of the present disclosure, the frequency measurement configuration information may be configured as different Information Elements (IEs) for the RRC idle mode and the RRC deactivated mode. That is, depending on the RRC mode to which the UE transitions, the gNB may result in different configuration information being included and may indicate frequency measurements. Further, the UE may store the results measured in the RRC idle mode and the RRC deactivation mode in different variables, and may report the results differently. Since the RRC idle mode and the RRC deactivation mode are different from each other in configuring a connection to a network and a specific operation, configuration information (a frequency measurement list, a timer value (duration), or a validity area) and a configuration result reporting variable can be more effectively managed, respectively.

Embodiments of the present disclosure may provide fast frequency measurement operations and methods that efficiently process frequency configuration information or frequency measurement results when a UE in an RRC deactivated mode transitions to an RRC idle mode for some reason. Embodiments of the present disclosure may provide certain causes of state transition of a UE and an efficient method corresponding to the certain causes. Furthermore, embodiments of the present disclosure may provide a method of performing a frequency measurement operation when an RRC idle mode UE accesses another radio access technology.

1. When an RRC deactivated mode UE configured with fast frequency measurement configuration information is received in a paging message, the RRC deactivated mode UE may need to perform a state transition when a System Architecture Evolution (SAE) -temporary Mobile subscriber identity (S-TMSI), 5G-S-TMSI, or International Mobile Subscriber Identity (IMSI) is received in the paging message instead of deactivating a radio network temporary identifier (I-RNTI), i.e., when an RRC deactivated mode terminal may need to transition from an RRC deactivated mode to an RRC idle mode

A. The method comprises the following steps: even after the transition to the RRC idle mode, the UE may keep performing frequency measurement based on previously configured fast frequency measurement configuration information. Accordingly, when a connection to the network is performed later, the UE can quickly report the frequency measurement result. In this case, the previously configured fast frequency measurement configuration information may include a value of a first timer indicating a time when the UE is to perform frequency measurement, and the UE may not stop the first timer (e.g., T331) when transitioning from the RRC deactivation mode to the RRC idle mode. That is, by continuously driving the first timer, the UE can keep performing frequency measurement even when a state transition occurs while the first timer is running. When the first timer expires, the UE may release or discard the frequency measurement information or the frequency measurement result (the frequency measurement result may be discarded by the second timer). In another method, when transitioning from the RRC deactivated mode to the RRC idle mode, the UE may keep performing the frequency measurement result by restarting a first timer (e.g., T331) based on a duration value configured in the rrcreelease message.

B. Method 2 the UE may discard the UE context when transitioning to the RRC idle mode, may stop a timer for frequency measurement when the timer runs, and may determine that previously configured frequency measurement information or frequency measurement results are no longer valid and may discard the previously configured frequency measurement information or frequency measurement results. Because the UE context is discarded, the UE may determine that the existing configuration is invalid. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting.

2. When the RRC deactivation mode UE configured with the fast frequency measurement configuration information may perform an RRC connection recovery procedure to configure a connection to a network, an RRCResumeRequest message may be transmitted as message 3, an RRCSetup message in response to message 3 may be received, and it may be necessary to perform a state transition, i.e., when the RRC deactivation mode UE falls back to an RRC idle mode

A. Method 1 the UE may discard the UE context when transitioning to the RRC idle mode, may stop a timer for frequency measurement while the timer is running, and may determine that previously configured frequency measurement information or frequency measurement results are no longer valid and may discard the previously configured frequency measurement information or frequency measurement results. Because the UE context is discarded, the UE may determine that the existing configuration is invalid. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting. In this case, the previously configured fast frequency measurement configuration information may include a value of a first timer indicating a time when the UE is to perform frequency measurement, and the UE may not stop the first timer (e.g., T331) when transitioning from the RRC deactivation mode to the RRC idle mode. That is, by continuously driving the first timer, the UE can keep performing frequency measurement even when a state transition occurs while the first timer is running. When the first timer expires, the UE may release or discard the frequency measurement information or the frequency measurement result (the frequency measurement result may be discarded by the second timer). In another method, when transitioning from the RRC deactivated mode to the RRC idle mode, the UE may keep performing the frequency measurement result by restarting a first timer (e.g., T331) based on a duration value configured in the rrcreelease message.

B. Method 2 the UE may discard the UE context but may not discard the frequency measurement when transitioning to RRC idle mode and may report to the gNB so that the gNB uses the frequency measurement. For example, when the UE transmits the RRCSetupComplete message as message 5, the UE may define an indicator of the RRCSetupComplete message indicating the presence measurement result, and may indicate the presence measurement result to the gNB by using the indicator. The UE may release the frequency measurement configuration information. Further, when a separate frequency measurement result request message (e.g., uelnformationrequest) is received from the gNB, the UE may cause a frequency measurement result (e.g., uelnformationresponse) to be included in a separate response message, may transmit the separate response message to the gNB, and may discard the stored frequency measurement result.

3. When the T319 timer run by the RRC deactivation mode UE configured with the fast frequency measurement configuration information expires, i.e., when the UE has to transition to the RRC idle mode due to the T319 timer expiring (the T319 timer starts when message 3 (e.g., RRCResumeRequest) is transmitted and stops when message 4 (e.g., rrcreesume or RRCSetup or rrcreelease) is received).

A. The method comprises the following steps: even after the transition to the RRC idle mode, the UE may keep performing frequency measurement based on previously configured fast frequency measurement configuration information. Accordingly, when a connection to the network is performed later, the UE can quickly report the frequency measurement result. The previously configured fast frequency measurement configuration information may include a value of a first timer indicating a time when the UE is to perform frequency measurement, and the UE may not stop the first timer (e.g., T331) when transitioning from the RRC deactivation mode to the RRC idle mode. That is, by continuously driving the first timer, the UE can keep performing frequency measurement even when a state transition occurs while the first timer is running. When the first timer expires, the UE may release or discard the frequency measurement information or the frequency measurement result (the frequency measurement result may be discarded by the second timer). In another method, when transitioning from the RRC deactivated mode to the RRC idle mode, the UE may keep performing the frequency measurement result by restarting a first timer (e.g., T331) based on a duration value configured in the rrcreelease message.

B. Method 2 the UE may discard the UE context when transitioning to the RRC idle mode, may stop a timer for frequency measurement while the timer is running, and may determine that previously configured frequency measurement information or frequency measurement results are no longer valid and may discard the previously configured frequency measurement information or frequency measurement results. Because the UE context is discarded, the UE may determine that the existing configuration is invalid. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting.

4. Failing to find a suitable cell when performing cell reselection in an RRC deactivated state, waiting for an acceptable cell to provide only limited service, and transitioning to an RRC idle mode when an RRC deactivated mode UE configured with fast frequency measurement configuration information fails to find a suitable cell, and transitions to an RRC idle mode

B. Method 2 the UE may discard the UE context when transitioning to the RRC idle mode and may stop the timer for frequency measurement when the timer runs and may determine that previously configured frequency measurement information or frequency measurement results are no longer valid and may discard the previously configured frequency measurement information or frequency measurement results. Because the UE context is discarded, the UE may determine that the existing configuration is invalid. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting.

5. When the RRC deactivation mode UE configured with the fast frequency measurement configuration information performs an RRC connection recovery procedure to configure a connection to a network, an rrcresemequest message is transmitted as message 3 and an rrcresememe message is received in response to message 3, but the RRC deactivation mode UE may not follow the configuration of the rrcresememe message or may not apply the configuration information (e.g., in the RRC deactivation mode UE, the RRC deactivation mode UE may not follow the configuration of the rrcresememe message or may not apply the configuration information). UE context restoration is typically not performed in the gNB or UE, so the RRC deactivated mode UE may need to perform state transitions, i.e., when the RRC deactivated mode UE may need to transition to RRC idle mode

A. Method 1 the UE may discard the UE context when transitioning to the RRC idle mode, may stop a timer for frequency measurement while the timer is running, and may determine that previously configured frequency measurement information or frequency measurement results are no longer valid and may discard the previously configured frequency measurement information or frequency measurement results. Because the UE context is discarded, the UE may determine that the existing configuration is invalid. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting. The previously configured fast frequency measurement configuration information may include a value of a first timer indicating a time when the UE is to perform frequency measurement, and the UE may not stop the first timer (e.g., T331) when transitioning from the RRC deactivation mode to the RRC idle mode. That is, by continuously driving the first timer, the UE can keep performing frequency measurement even when a state transition occurs while the first timer is running. When the first timer expires, the UE may release or discard the frequency measurement information or the frequency measurement result (the frequency measurement result may be discarded by the second timer). In another method, when transitioning from the RRC deactivation method to the RRC idle mode, the UE may continue to perform the frequency measurement result by restarting the first timer (e.g., T331) based on the duration value configured in the rrcreelease message.

B. Method 2 the UE may discard the UE context but may not discard the frequency measurements when transitioning to RRC idle mode and may report to the gNB so that the gNB uses the measurements. For example, when the UE transmits the RRCSetupComplete message as message 5, the UE may define an indicator of the RRCSetupComplete message indicating the presence measurement result, and may indicate the presence measurement result to the gNB by using the indicator. The UE may release the frequency measurement configuration information. Further, when receiving a separate frequency measurement request message (e.g., uelnformationrequest) from the gNB, the UE may cause the frequency measurement (e.g., uelnformationresponse) to be included in a separate response message, may transmit the separate response message to the gNB, and may discard the stored frequency measurement.

6. When an RRC deactivated mode UE configured with fast frequency measurement configuration information reselects a cell using another radio access technology while performing a cell reselection procedure, the camped cell (in the case of inter-RAT reselection) and may need to transition to an RRC idle mode

C. The method 3 comprises the following steps:

i. when another radio access technology used by the cell selected or camped on by the UE through the cell reselection procedure and on which the UE is camped is the LTE system connected to the 5G Core Network (CN) or the LTE system or the NR system connected to the Evolved Packet Core (EPC),

1. even after the transition to the RRC idle mode, the UE may keep performing frequency measurement based on previously configured fast frequency measurement configuration information. Accordingly, when a connection to the network is performed later, the UE can quickly report the frequency measurement result. The previously configured fast frequency measurement configuration information may include a value of a first timer indicating a time when the UE is to perform frequency measurement, and the UE may not stop the first timer (e.g., T331) when transitioning from the RRC deactivation mode to the RRC idle mode. That is, by continuously driving the first timer, the UE can keep performing frequency measurement even when a state transition occurs while the first timer is running. When the first timer expires, the UE may release or frequency measurement information or frequency measurement results (which may be discarded by the second timer). In another method, when transitioning from the RRC deactivated mode to the RRC idle mode, the UE may keep performing the frequency measurement result by restarting a first timer (e.g., T331) based on a duration value configured in the rrcreelease message.

Else, when the other radio access technology used by the cell selected or camped by the UE through the cell reselection procedure is a system other than the LTE system connected to the 5G CN or the LTE system or the NR system connected to the EPC (e.g., Universal Mobile Telecommunications System (UMTS) or a second generation (2G) system), or when the other radio access technology used by the cell selected or camped by the UE through the cell reselection procedure is UMTS (3G) or a Global System for Mobile communications (GSM) edge radio Access network (GERAN) (2G),

the UE may discard the UE context when transitioning to the RRC idle mode, may stop a timer for frequency measurement while the timer is running, and may determine that previously configured frequency measurement information or frequency measurement is no longer valid and may discard the previously configured frequency measurement information or frequency measurement. Because the UE context is discarded, the UE may determine that the existing configuration is invalid. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting.

7. Transmitting a RRCRequeRequest message as a message 3 when an RRC deactivation mode UE configured with fast frequency measurement configuration information performs an RRC connection recovery procedure to configure a connection to a network, receiving a RRCRreject message or a RRCRelease message in response to the message 3, and needing to perform a state transition, i.e., when the RRC deactivation mode UE returns to an RRC idle mode

A. Method 1 the UE may discard the UE context when transitioning to the RRC idle mode, may stop a timer for frequency measurement while the timer is running, and may determine that previously configured frequency measurement information or frequency measurement results are no longer valid and may discard the previously configured frequency measurement information or frequency measurement results. In this case, the UE may determine that the existing configuration is invalid because the UE context is discarded. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting. The previously configured fast frequency measurement configuration information may include a value of a first timer indicating a time when the UE is to perform frequency measurement, and the UE may not stop the first timer (e.g., T331) when transitioning from the RRC deactivation mode to the RRC idle mode. That is, by continuously driving the first timer, the UE can keep performing frequency measurement even when a state transition occurs while the first timer is running. When the first timer expires, the UE may release or discard the frequency measurement information or the frequency measurement result (the frequency measurement result may be discarded by the second timer). In another method, when transitioning from the RRC deactivated mode to the RRC idle mode, the UE may keep performing the frequency measurement result by restarting a first timer (e.g., T331) based on a duration value configured in the rrcreelease message.

B. Method 2 the UE may discard the UE context when transitioning to the RRC idle mode, may stop a timer (e.g., a first timer) for frequency measurement while the timer is running, may determine that previously configured frequency measurement information or frequency measurements are no longer valid, and may discard the previously configured frequency measurement information or frequency measurements. In this case, the UE may determine that the existing configuration is invalid because the UE context is discarded. In another approach, the UE may discard only the frequency measurement information and may use the frequency measurement results for later reporting.

The following embodiments of the present disclosure provide a method of performing fast frequency measurement operations when an LTE or NR RRC idle mode UE is connected to another radio access technology.

8. When the other radio access technology used by the cell selected or camped on by the RRC idle mode UE through the cell reselection procedure (inter-RAT reselection) is an LTE system connected to the 5G CN or a system other than the LTE system or the NR system connected to the EPC (e.g., UMTS or 2G system), or when the other radio access technology used by the cell selected or camped on by the RRC idle mode UE is UMTS (3G) or GERAN (2G),

An rrc idle mode UE may stop a timer (e.g., a first timer) for frequency measurement while the timer is running, and may determine that previously configured frequency measurement information or frequency measurement results are no longer valid, and may discard the previously configured frequency measurement information or frequency measurement results.

Fig. 1L is a schematic diagram for describing an operation of a terminal performing RRC idle mode or RRC deactivated mode frequency measurement and reporting a measurement result according to an embodiment of the present disclosure.

Referring to fig. 1L, when the terminal receives an RRC message, the terminal may drive a timer for RRC idle mode or RRC deactivation mode frequency measurement.

In operation 1l-05, the terminal may determine whether frequency measurement configuration information for RRC idle mode or RRC deactivated mode frequency measurement exists in the RRC message.

In operations 1l-10, the terminal may perform an RRC idle mode or an RRC deactivated mode frequency measurement based on the frequency measurement configuration information. When there is no frequency measurement configuration information for RRC idle mode or RRC deactivation mode frequency measurement in the RRC message, the terminal may receive frequency measurement information from the system information and may perform RRC idle mode or RRC deactivation mode frequency measurement. In case of the RRC deactivation mode terminal, an RRC message may be received in the RAN notification area update procedure, and frequency measurement may be continuously performed through newly configured frequency measurement information whenever the RAN notification area update procedure is performed. When the terminal performs the frequency measurement, the terminal may store the measurement result.

When there is an indicator indicating that RRC idle mode or RRC deactivation mode frequency measurement can be supported in system information of a cell configuring a connection to a network, the terminal may transmit a message 3 when configuring a connection to a network. When the base station can cause the indicator to indicate that the frequency measurement result is included in the message 4 and can transmit the message 4, the terminal can stop the timer in operations 1 l-15.

Further, in operation 1l-20, the terminal may include the RRC idle mode or RRC deactivation mode frequency measurement result in message 5, and may transmit message 5. The terminal may discard the measurement results when the measurement results are successfully delivered to the base station.

Fig. 1M is a block diagram illustrating a structure of a terminal according to an embodiment of the present disclosure.

Referring to fig. 1M, a terminal may include a Radio Frequency (RF) processor 1M-10, a baseband processor 1M-20, a memory 1M-30, and a controller 1M-40.

The 360RF processors 1m-10 may perform functions of transmitting/receiving signals through radio channels, such as band conversion or amplification of signals. That is, the RF processors 1m-10 may up-convert baseband signals provided from the baseband processors 1m-20 into RF band signals, and then may transmit the RF band signals through the antennas, and may down-convert RF band signals received through the antennas into baseband signals. For example, the RF processors 1m-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, digital-to-analog converters (DACs), and analog-to-digital converters (ADCs). Although only one antenna is shown in fig. 1M, the terminal may include a plurality of antennas. Also, the RF processors 1m-10 may include a plurality of RF chains. In addition, the RF processors 1m-10 may perform beamforming. For beamforming, the RF processors 1m-10 may adjust the phase and magnitude of each signal transmitted/received through a plurality of antennas or antenna elements. Also, the RF processors 1m-10 may perform MIMO and may receive multiple layers during MIMO operation. The RF processors 1m-10 may perform receive beam scanning by appropriately configuring a plurality of antennas or antenna elements, or may adjust the direction and beam width of the receive beam under the control of the controllers 1m-40 so that the receive beam is coordinated with the transmit beam.

The baseband processors 1m-20 may convert between baseband signals and bit streams according to the physical layer specifications of the system. For example, during data transmission, the baseband processors 1m-20 may generate complex symbols by encoding and modulating a transmission bit stream. Further, during data reception, the baseband processors 1m-20 may reconstruct a reception bit stream by demodulating and decoding the baseband signals provided from the RF processors 1 m-10. For example, according to an Orthogonal Frequency Division Multiplexing (OFDM) method, during data reception, the baseband processors 1m-20 may generate complex symbols by encoding and modulating a transmission bit stream, may map the complex symbols to subcarriers, and may configure OFDM symbols by Inverse Fast Fourier Transform (IFFT) and Cyclic Prefix (CP) insertion. Further, during data reception, the baseband processors 1m-20 may segment the baseband signals provided from the RF processors 1m-10 into OFDM symbols, may reconstruct signals mapped to subcarriers through Fast Fourier Transform (FFT), and may then reconstruct received bit streams through demodulation and decoding of the signals.

As described above, the baseband processors 1m-20 and the RF processors 1m-10 can transmit and receive signals. Thus, the baseband processors 1m-20 and the RF processors 1m-10 may be referred to as transmitters, receivers, transceivers or communicators. Further, at least one of the baseband processors 1m-20 or the RF processors 1m-10 may include a plurality of communication modules supporting a plurality of different radio access technologies. Further, at least one of the baseband processors 1m-20 or the RF processors 1m-10 may include different communication modules to process signals of different frequency bands. For example, the different radio access technologies may include LTE networks and NR networks. Also, the different frequency bands may include an ultra high frequency (SHF) (e.g., 2.5GHz or 5GHz) frequency band and a millimeter wave (mmWave) (e.g., 60GHz) frequency band.

The memories 1m-30 may store basic programs, application programs, and data such as configuration information for operating the terminal. The memories 1m-30 may provide stored data upon request of the controllers 1 m-40.

The controllers 1m-40 may control the overall operation of the terminal. For example, the controller 1m-40 may transmit/receive signals through the baseband processor 1m-20 and the RF processor 1 m-10. In addition, the controller 1m-40 can write data to the memory 1m-40 and read data from the memory 1 m-40. To this end, the controllers 1m-40 may include at least one processor. For example, the controllers 1m-40 may include a Communication Processor (CP) for controlling communication and an Application Processor (AP) for controlling an upper layer such as an application program.

Fig. 1N is a block diagram illustrating a structure of a base station (e.g., a Transmit Receive Point (TRP)) in accordance with an embodiment of the present disclosure.

As shown in fig. 1N, the base station may include RF processors 1N-10, baseband processors 1N-20, backhaul communicators 1N-30, memories 1N-40, and controllers 1N-50.

The RF processors 1n-10 may perform functions of transmitting/receiving signals through a radio channel, such as band conversion or amplification of the signals. That is, the RF processors 1n-10 may up-convert baseband signals provided from the baseband processors 1n-20 into RF band signals, and then may transmit the RF band signals through the antennas, and may down-convert RF band signals received through the antennas into baseband signals. For example, the RF processors 1n-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, DACs, and ADCs. Although only one antenna is shown in fig. 1N. In this case, the first connection node may include a plurality of antennas. Further, the RF processors 1n-10 may include a plurality of RF chains. In addition, the RF processors 1n-10 may perform beamforming. For beamforming, the RF processors 1n-10 may adjust the phase and magnitude of each signal transmitted/received through a plurality of antennas or antenna elements. The RF processors 1n-10 may perform downlink MIMO operations by transmitting one or more layers.

The baseband processors 1n-20 may convert between baseband signals and bit streams according to the physical layer specification of the first radio access technology. For example, during data transmission, the baseband processors 1n-20 may generate complex symbols by encoding and modulating the transmission bit stream. Further, during data reception, the baseband processors 1n-20 may reconstruct a reception bit stream by demodulating and decoding the baseband signals provided from the RF processors 1 n-10. For example, according to the OFDM method, during data transmission, the baseband processors 1n-20 may generate complex symbols by encoding and modulating a transmission bit stream, may map the complex symbols to subcarriers, and may then configure the OFDM symbols through IFFT and CP insertion. Also, during data reception, the baseband processors 1n-20 may segment the baseband signals provided from the RF processors 1n-10 into OFDM symbols, may reconstruct signals mapped to subcarriers through FFT, and may then reconstruct received bit streams through demodulation and decoding of the signals. As described above, the baseband processors 1n-20 and the RF processors 1n-10 can transmit and receive signals. Thus, the baseband processors 1n-20 and the RF processors 1n-10 may be referred to as transmitters, receivers, transceivers, communicators, or wireless communicators.

The backhaul communicators 1n-30 may provide an interface for communicating with other nodes in the network.

The memories 1n-40 may store basic programs, application programs, and data such as configuration information for operating the base station. In particular, the memories 1n-40 may store information about bearers assigned to the connected terminals and measurement results reported from the connected terminals. Furthermore, the memories 1n-40 may store standard information for determining whether to provide or cease multi-connectivity to the terminal. The memories 1n-40 may provide stored data upon request of the controllers 1 n-50.

The controllers 1n-50 may control the overall operation of the base station. For example, the controller 1n-50 may transmit/receive signals through the RF processor 1n-10 and the baseband processor 1n-20 or the backhaul communicator 1 n-30. In addition, the controllers 1n-50 can write data to the memories 1n-40 and read data from the memories 1 n-40. To this end, the controllers 1n-50 may comprise at least one processor.

In a wireless communication system, a high frequency band and a wide bandwidth are used for a downlink, so that a large amount of transmission resources can be secured. Also, since a large number of antennas may be physically installed and used for the base station, beamforming gain and high signal strength may be achieved, and thus more data may be transmitted to the terminal in the downlink by using the same frequency/time resources. However, since the terminal has a physically small size and a high frequency band and a wide bandwidth is not easily used for an uplink, a bottleneck phenomenon may occur in an uplink transmission resource compared to a downlink transmission resource. Also, since the maximum transmission power level of the terminal is much less than that of the base station, a reduction in the coverage of uplink data transmission occurs. Therefore, it is necessary to efficiently use transmission resources by compressing uplink data.

One method of compressing uplink data may be a method of performing data compression serially based on previous data. Thus, when one data in a series of compressed data is lost or discarded or experiences a decompression failure, decompression may fail for all data after the data is lost or discarded or experiences a decompression failure.

The transmitting PDCP layer may drive a PDCP discard timer for each data whenever data is received from an upper layer, may perform an uplink compression procedure when the uplink compression procedure is configured, may configure an Uplink Data Compression (UDC) header, may perform ciphering on data on which the uplink data compression is performed, and may generate a PDCP Packet Data Unit (PDU) by allocating a PDCP sequence number and configuring the PDCP header. When the PDCP discard timer expires, the transmitting PDCP layer may assume that data corresponding to the PDCP discard timer is no longer valid and may discard the data.

Accordingly, once the transmitting PDCP layer discards previously generated data (e.g., PDCP PDUs) due to expiration of the PDCP discard timer, one of a series of compressed data is discarded, and thus continuous data decompression failure may occur in the receiving PDCP layer due to the discarded or lost compressed data.

Embodiments of the present disclosure may provide a procedure in which a transmitting PDCP layer (terminal or base station) in a wireless communication system compresses and transmits data in an uplink or downlink, and a receiving PDCP layer (base station or terminal) receives and decompresses the data. Further, embodiments of the present disclosure may provide a method of supporting a data transmission/reception procedure in which a transmitter side compresses and transmits data and a receiver side decompresses the data (such as a specific header format), a method of solving a decompression failure, and a method of solving a problem when a transmitting PDCP layer discards data due to a PDCP discard timer. Further, the method may be applied to a process in which the base station compresses downlink data and transmits the compressed downlink data to the terminal, and the terminal receives and decompresses the compressed downlink data. According to the embodiments of the present disclosure, since data is compressed and transmitted at the transmitter end, more data can be transmitted and coverage can be improved.

In addition, when a data decompression error occurs in the receiving PDCP layer or the received compressed data is processed, embodiments of the present disclosure can provide an efficient operation of the receiving PDCP layer according to an indicator of a user data compression header.

Further, while the present disclosure is described, a detailed description of related well-known functions or configurations, which may obscure the gist of the present disclosure, is omitted. Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

Hereinafter, for convenience of explanation, terms indicating a connection node, terms indicating a network entity, terms indicating a message, terms indicating an interface between network entities, and terms indicating various identification information, which are used in the following description, are exemplified. Accordingly, the present disclosure is not limited to terms that will be described later, but other terms indicating objects having the same technical meaning may be used.

Hereinafter, for convenience of explanation, the present disclosure uses terms and names defined in the third generation partnership project long term evolution (3GPP LTE) standard. However, the present disclosure is not limited to the above terms and names, and may also be applied to systems that comply with other standards. In this disclosure, for ease of explanation, eNB may be used interchangeably with gNB. That is, a base station described as an eNB may refer to a gbb.

Fig. 2A is a schematic diagram illustrating a structure of an LTE system according to an embodiment of the present disclosure.

Referring to fig. 2A, a radio access network of an LTE system may include evolved node bs (enbs) (node bs or base stations) 2A-05, 2A-10, 2A-15, and 2A-20, Mobility Management Entities (MMEs) 2A-25, and serving gateways (S-GWs) 2A-30. User Equipment (UE)2a-35 may connect to an external network through ENBs 2a-05, 2a-10, 2a-15, and 2a-20 and S-GW 2 a-30.

In FIG. 2A, ENBs 2A-05, 2A-10, 2A-15, and 2A-20 may correspond to existing node Bs of UMTS. Each ENB may be connected to the UEs 2a-35 through a radio channel and may perform more complex functions than existing node bs. Since all user traffic data including real-time services such as voice over internet protocol (VoIP) is served through a shared channel in the LTE system, an entity for collecting and scheduling buffer status information, available transmission power status information, and channel status information of UEs may be required, and each of the ENBs 2a-05 to 2a-20 may serve as such an entity. One ENB may generally control a plurality of cells. For example, to achieve a data rate of 100Mbps, the LTE system may use Orthogonal Frequency Division Multiplexing (OFDM) of a 20MHz bandwidth as a radio access technology. Further, Adaptive Modulation and Coding (AMC) for determining a modulation scheme and a channel coding rate according to the channel status of the UEs 2a-35 may be applied. The S-GW 2a-30 is an entity for providing data bearers and may generate or remove data bearers under the control of the MME 2 a-25. An MME 2a-25, which is an entity for performing various control functions as well as mobility management functions on the UE 2a-35, may be connected to a plurality of ENBs.

Fig. 2B is a schematic diagram illustrating a radio protocol architecture in an LTE system according to an embodiment of the present disclosure.

Referring to FIG. 2B, a radio protocol architecture of the LTE system includes Packet Data Convergence Protocol (PDCP) layers 2B-05 and 2B-40, Radio Link Control (RLC) layers 2B-10 and 2B-35, and Medium Access Control (MAC) layers 2B-15 and 2B-30 for the UE and the ENB, respectively. The PDCP layers 2b-05 and 2b-40 may be responsible for, for example, IP header compression/decompression. The main functions of each PDCP layer can be summarized as follows.

Header compression and decompression: ROHC only

-transferring user data

In-order delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM

-duplicate detection of lower layer SDUs during PDCP re-establishment for RLC AM

-encryption and decryption

Timer-based SDU discard in uplink

Each of the RLC layers 2b-10 and 2b-35 can perform an ARQ operation by reconfiguring a PDCP Packet Data Unit (PDU) to an appropriate size. The main functions of each RLC layer can be summarized as follows.

-transmission of upper layer PDU

Error correction by ARQ (for AM data transfer only)

Concatenation, segmentation and reassembly of RLC SDUs (for UM and AM data transfer only)

Re-segmentation of RLC data PDUs (for AM data transfer only)

Reordering of RLC data PDUs (for UM and AM data transfer only)

Duplicate detection (for UM and AM data transfer only)

Protocol error detection (for AM data transfer only)

RLC SDU discard (for UM and AM data transfer only)

RLC re-establishment

The MAC layers 2b-15 and 2b-30 are connected to various RLC layers configured in one UE, and can multiplex RLC PDUs into MAC PDUs and demultiplex RLC PDUs from the MAC PDUs. The main functions of each MAC layer can be summarized as follows.

Mapping between logical channels and transport channels

-multiplexing or demultiplexing MAC SDUs belonging to one or different logical channels into or from Transport Blocks (TBs) delivered to or from the physical layer on the transport channel

-scheduling information reporting

Error correction by HARQ

-priority handling between logical channels of one UE

-prioritization among UEs by dynamic scheduling

412-MBMS service identification

-transport format selection

-filling

Each of the Physical (PHY) layers 2b-20 and 2b-25 may channel-encode and modulate upper layer data into OFDM symbols and transmit the OFDM symbols through a radio channel, or demodulate OFDM symbols received through a radio channel and decode the channel and deliver the OFDM symbols to the upper layer.

Fig. 2C is a schematic diagram illustrating the structure of a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 2C, a radio access network of a next generation mobile communication system (e.g., NR or 5G system) may include a new wireless node B (NR gbb or NR base station) 2C-10 and a new radio core network (NR CN) 2C-05. The new wireless user equipment (NR UE)2c-15 may connect to an external network through NR gNB 2c-10 and NR CN 2 c-05.

In fig. 2C, NR gNB 2C-10 corresponds to an evolved node b (enb) of an existing LTE system. The NR gbb 2c-10 may be connected to the NR UE 2c-15 through a radio channel and may provide better service than the existing node B. Since all user traffic data is served through a shared channel in the next generation mobile communication system, an entity for collecting and scheduling buffer status information, available transmission power status information, and channel status information of UEs may be required, and the NR NB 2c-10 may serve as such an entity. One NR gbb 2c-10 may typically control multiple cells. The next generation mobile communication system may currently have a bandwidth greater than the maximum bandwidth of the existing LTE to achieve an ultra-high data rate, may use Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology, and may additionally use a beamforming technology. Further, Adaptive Modulation and Coding (AMC) for determining a modulation scheme and a channel coding rate according to the channel status of the NR UEs 2c-15 may be applied. The NR CN 2c-05 may perform functions such as mobility support, bearer configuration, and QoS configuration. The NR CN 2c-05, which is an entity for performing various control functions and mobility management functions on the NR UE 2c-15, is connected to a plurality of base stations. Further, the next generation mobile communication system can cooperate with the existing LTE system, and the NR CN 2c-05 can be connected with the MME 2c-25 through a network interface. The MME 2c-25 may be connected to the eNB 2c-30 as an existing base station.

Fig. 2D is a schematic diagram illustrating a radio protocol architecture of a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to FIG. 2D, a radio protocol architecture of the next generation mobile communication system may include NR PDCP layers 2D-05 and 2D-40, NR RLC layers 2D-10 and 2D-35, and NR MAC layers 2D-15 and 2D-30, and NR gNB in the UE. The main functions of each of the NR PDCP layers 2d-05 and 2d-40 may include some of the following functions.

Header compression and decompression: ROHC only

-transferring user data

-sequential delivery of upper layer PDUs

Out-of-order delivery of upper layer PDUs

-PDCP PDU reordering for reception

Duplicate detection of lower layer SDU

-retransmission of PDCP SDU

-encryption and decryption

Timer-based SDU discard in uplink

The main functions of the NR RLC layers 2d-10 and 2d-35 may include some of the following functions.

-transmission of upper layer PDU

-sequential delivery of upper layer PDUs

Out-of-order delivery of upper layer PDUs

Error correction by ARQ

Concatenation, segmentation and reassembly of RLC SDUs

-re-segmentation of RLC data PDUs

Reordering of RLC data PDUs

-duplicate detection

-protocol error detection

RLC SDU discard

RLC re-establishment

In the above description, the sequential delivery function of the NR RLC layer may refer to a function of sequentially delivering RLC SDUs received from a lower layer to an upper layer, and may include at least one of the following functions: a function of reassembling a plurality of RLC SDUs segmented from one RLC SDU, and a function of delivering the reassembled RLC SDU when the segmented RLC SDU is received, a function of reordering the received RLC PDUs based on RLC SN or PDCP SN. A function of recording a missing RLC PDU by reordering received RLC PDUs, a function of reporting status information of the missing RLC PDU to a transmitter, a function of requesting retransmission of the missing RLC PDU, a function of delivering only RLC SDUs before the missing RLC SDU to an upper layer when the missing RLC SDU exists, a function of delivering all RLC SDUs received before the timer starts to the upper layer when the missing RLC SDU exists when a certain timer expires, or a function of delivering all RLC SDUs received until the current time until the missing RLC SDU is received to the upper layer when the certain timer expires. Further, the NR RLC layer may process RLC PDUs in the order of reception (in the order of arrival regardless of SN) and deliver the RLC PDUs to the PDCP layer out of order (regardless of sequence delivery order), or reassemble segmented RLC PDUs received or stored in a buffer into the entire RLC PDU and process and deliver the RLC PDUs to the PDCP layer. The NR RLC layer may have no concatenation function, and the concatenation function may be performed by the NR MAC layer or may be replaced by a multiplexing function of the NR MAC layer.

The out-of-order delivery function of the NR RLC layer refers to a function of delivering RLC SDUs received from a lower layer directly to an out-of-order upper layer, and may include a function of reassembling a plurality of RLC SDUs segmented from one RLC SDU upon receipt of the segmented RLC SDUs and delivering the reassembled RLC SDUs, and a function of recording missing RLC PDUs by storing RLC SNs or PDCP SNs of the received RLC PDUs and reordering the received RLC PDUs.

Each of the NR MAC layers 2d-15 and 2d-30 may be connected to a plurality of NR RLC layers configured for one UE, and the main functions of each NR MAC layer may include some of the following functions.

Mapping between logical channels and transport channels

-multiplexing/demultiplexing of MAC SDUs

-scheduling information reporting

Error correction by HARQ

-priority handling between logical channels of one UE

-prioritization among UEs by dynamic scheduling

-MBMS service identification

-transport format selection

-filling

Each of the NR PHY layers 2d-20 and 2d-25 may channel-encode and modulate upper layer data into OFDM symbols and transmit the OFDM symbols through a radio channel, or may demodulate OFDM symbols received through a radio channel and decode the channel and deliver the OFDM symbols to the upper layer.

Embodiments of the present disclosure may provide a process in which a terminal in a wireless communication system compresses and transmits data in an uplink, and a base station decompresses the data. Further, embodiments of the present disclosure may provide a method in which a transmitter compresses and transmits data, and a receiver decompresses data (e.g., a specific header format) in support of a data transmission/reception process, or a method of solving decompression failure. Further, the method according to the embodiment of the present disclosure is applied to a process in which a base station compresses downlink and transmits compressed downlink data to a terminal, and the terminal receives and decompresses the compressed downlink data. According to the embodiments of the present disclosure, since data is compressed and transmitted at the transmitter end, more data can be transmitted and coverage can be improved.

Fig. 2E is a schematic diagram for describing a procedure in which when a UE configures a connection to a network, a gNB configures whether to perform uplink data compression, according to an embodiment of the present disclosure.

Referring to fig. 2E, in the present embodiment of the present disclosure, a procedure in which a UE switches from an RRC idle mode or an RRC deactivated (lightly connected) mode to an RRC connected mode and configures a connection to a network will be described. Further, a procedure of configuring whether to perform Uplink Data Compression (UDC) will be described.

In operation 2e-01, when the UE transmitting/receiving data in the RRC connected mode does not transmit/receive data for a certain period of time or for a certain reason, the gNB may transmit an RRC connection release message to the UE, so that the UE switches to the RRC idle mode. When a UE that is not currently connected to the network (hereinafter referred to as an idle mode UE) has data to transmit, the UE may perform an RRC connection setup procedure with the gNB.

In operation 2e-05, the UE may establish backward transmission synchronization with the gNB through a random access procedure and may transmit an RRCConnectionRequest (RRC connection request) message to the gNB. The RRCConnectionRequest message may include an identifier of the UE, an establishment cause, and the like.

In operation 2e-10, the gNB may send an RRCConnectionSetup message in order for the UE to configure the RRC connection. The RRCConnectionSetup message may include information indicating whether an Uplink Data Compression (UDC) method or a downlink data compression method is used for each logical channel (logical channel configuration), each bearer, or each PDCP entity (PDCP configuration). In addition, in more detail, the RRCConnectionSetup message may indicate whether to use an Uplink Data Compression (UDC) method, which is only for which IP flow or which QoS flow in each logical channel, each bearer, or each PDCP entity (or Service Data Adaptation Protocol (SDAP) entity) (e.g., information on IP flows or QoS flows to use or not use the uplink data compression method may be configured in the SDAP entity so that the SDAP entity may indicate whether the PDCP entity uses the uplink data compression method for each QoS flow). Further, when the gNB may indicate that the uplink data compression method is used, the gNB may indicate an identifier of a predefined library or dictionary to be used in the uplink data compression method or a buffer size to be used in the uplink data compression method.

Also, the RRCConnectionSetup message may include an uplink decompression setup or release command. Further, when the gNB configures an uplink data compression method to be used, the gNB may always configure the uplink data compression method using an RLC AM bearer (due to lossless mode of an ARQ function and a retransmission function), and may not configure using a header compression protocol (e.g., ROHC protocol). Also, the RRCConnectionSetup message may include RRC connection configuration information. The RRC connection may be referred to as a Signaling Radio Bearer (SRB) and may be used to transmit/receive RRC messages that are control messages between the UE and the gNB.

In operation 2e-15, the UE configuring the RRC connection may send an rrcconnectionsetupcomplete message to the gNB. The gNB may send a UE capability query message when the gNB does not know or want to check the UE capabilities of the UE configuring the current connection. The UE may send a UE capability report message. The UE capability report message may include an indicator indicating whether the UE can use an Uplink Data Compression (UDC) method or a downlink data compression method. The rrcconnectionsetupcomplete message may include a SERVICE REQUEST message, which is a control message for requesting the MME to configure a bearer for a certain SERVICE.

In operation 2e-20, the gNB may transmit a SERVICE REQUEST message included in the rrcconnectionsetupcomplete message to the MME, and the MME may determine whether to provide the SERVICE requested by the UE.

When the MME determines to provide the service requested by the UE, the MME may send an INITIAL CONTEXT SETUP REQUEST message to the gNB in operation 2 e-25. The INITIAL CONTEXT SETUP REQUEST message may include QoS information to be applied to configure a Data Radio Bearer (DRB) or security information (e.g., a security key or a security algorithm) to be applied to the DRB.

In operations 2e-01 and 2e-35, the gNB may exchange a SecurityModeCommand message and a SecurityModeComplete message to configure a security mode with the UE.

In operation 2e-40, when the security mode is fully configured, the gNB may send an RRCConnectionReconfiguration message to the UE. The RRCConnectionReconfiguration message may include information indicating whether to use an Uplink Data Compression (UDC) method or a downlink data compression method for each logical channel (logical channel configuration), each bearer, or each PDCP entity (PDCP configuration). In addition, in more detail, the RRCConnectionReconfiguration message may indicate whether to use an Uplink Data Compression (UDC) method only for which IP flow or which QoS flow in each logical channel, each bearer, or each PDCP entity (or SDAP entity) (e.g., information on IP flows or QoS flows that use or do not use the uplink data compression method may be configured in the SDAP entity so that the SDAP entity may indicate whether the PDCP entity uses the uplink data compression method for each QoS flow). Further, when the gNB may indicate that the uplink data compression method is used, the gNB may indicate an identifier of a predefined library or dictionary to be used in the uplink data compression method or a buffer size to be used in the uplink data compression method. Also, the RRCConnectionReconfiguration message may include an uplink decompression setup or release command. Further, when the gNB configures an uplink data compression method to be used, the gNB may always configure the uplink data compression method using an RLC AM bearer (due to lossless mode of an ARQ function and a retransmission function), and may not configure using a header compression protocol (e.g., ROHC protocol).

Further, the RRCConnectionReconfiguration message may include DRB configuration information for processing user data, and the UE may configure the DRB by applying the DRB configuration information and may transmit an RRCConnectionReconfiguration completion reconfiguration message to the gNB in operation 2 e-45.

In operation 2e-50, the gNB, which has fully configured the DRB with the UE, may send an INITIAL CONTEXT SETUP COMPLETE message to the MME.

In operations 2e-55 and 2e-60, the MME receiving the INITIAL CONTEXT SETUP COMPLETE message may exchange an S1 BEARER SETUP (S1 BEARER SETUP) message and an S1 BEARER SETUP RESPONSE (S1 BEARER SETUP RESPONSE) message with the S-GW to configure the S1 BEARER. The S1 bearer is a data transfer connection configured between the S-GW and the gNB, and may correspond to a DRB in a one-to-one manner.

When the above procedure is completed, the UE can transmit data to the gNB through the S-GW and receive data from the gNB in operations 2e-65 and 2 e-70. A general data transfer procedure may include three steps of RRC connection configuration, security configuration, and DRB configuration.

Further, in operation 2e-75, the gNB may send an RRCConnectionReconfiguration message to the UE to update, add, or change the configuration for some reason. The RRCConnectionReconfiguration message may include information indicating whether to use an Uplink Data Compression (UDC) method or a downlink data compression method for each logical channel (logical channel configuration), each bearer, or each PDCP entity (PDCP configuration). In addition, in more detail, the RRCConnectionReconfiguration message may indicate whether to use an Uplink Data Compression (UDC) method only for which IP flow or which QoS flow in each logical channel, each bearer, or each PDCP entity (or SDAP entity) (e.g., information on IP flows or QoS flows that use or do not use the uplink data compression method may be configured in the SDAP entity so that the SDAP entity may indicate whether the PDCP entity uses the uplink data compression method for each QoS flow). Further, when the gNB may indicate that the uplink data compression method is used, the gNB may indicate an identifier of a predefined library or dictionary to be used in the uplink data compression method or a buffer size to be used in the uplink data compression method. Also, the RRCConnectionReconfiguration message may include an uplink decompression setup or release command. Further, when the gNB configures an uplink data compression method to be used, the gNB may always configure the uplink data compression method using an RLC AM bearer (due to lossless mode of an ARQ function and a retransmission function), and may not configure using a header compression protocol (e.g., ROHC protocol).

Fig. 2F is a schematic diagram illustrating a data structure and a process of performing uplink or downlink data compression according to an embodiment of the present disclosure.

The uplink data 2f-05 may be generated as data corresponding to services such as video upload, photo upload, web browser, and voice over LTE (VoLTE). Data generated in the application layer may be processed through a network data transfer layer such as a transmission control protocol and internet protocol (TCP/IP) or a User Datagram Protocol (UDP), headers 2f-10 and 2f-15 may be configured, and may be delivered to the PDCP layer. When the PDCP layer receives data (PDCP SDU) from an upper layer, the PDCP layer may perform the following procedure.

When the uplink data compression method is configured to be used by the PDCP layer in the RRC message, as shown in operations 2E-10, 2E-40, or 2E-75 of FIG. 2E, the PDCP layer may perform the uplink data compression method for the PDCP SDU denoted by 2f-20, and may compress uplink data. In addition, the PDCP layer may configure a UDC header (header for compressing uplink data) 2f-25, may perform ciphering on compressed data other than the UDC header, may perform integrity protection at the time of configuration, may configure a PDCP header 2f-30, and may configure a PDCP PDU. The PDCP layer according to an embodiment of the present disclosure may include a UDC compression/decompression entity, may determine whether to perform a UDC procedure on each data configured in an RRC message, and may use the UDC compression/decompression entity. At the transmitter end, the transmitting PDCP layer may perform data compression by using a UDC compression entity, and at the receiver end, the receiving PDCP layer may perform data decompression by using a UDC decompression entity.

The procedure of fig. 2F may be applied when the terminal compresses downlink data as well as uplink data. Further, the description of uplink data may be applied to downlink data.

Fig. 2G is a schematic diagram for describing an uplink data compression method according to an embodiment of the present disclosure.

In more detail, fig. 2G is a schematic diagram for describing a DEFLATE-based uplink data compression algorithm. The DEFLATE-based uplink data compression algorithm is a lossless compression algorithm. The DEFLATE-based uplink data compression algorithm can basically compress uplink data by combining Huffman coding with the LZ77 algorithm. The LZ77 algorithm may include performing operations to search for repeated occurrences of data within a sliding window, and when repeated occurrences are found within the sliding window, performing data compression by representing the repeated data within the sliding window as a position and a length. In the Uplink Data Compression (UDC) method, the sliding window is called a buffer, and may be set to 8 kilobytes or 32 kilobytes. That is, the sliding window or buffer may record 8192 or 32768 characters, may find repeated occurrences of data, and may perform data compression by representing the repeated data as a position and a length. Therefore, since the LZ77 algorithm is a sliding window method, that is, since previously encoded data is updated in a buffer and then encoding is immediately performed on the next data, consecutive pieces of data may have a correlation therebetween. Therefore, only when previously encoded data is normally decoded, the next data can be normally decoded. Codes expressed as positions and lengths and compressed by using the LZ77 algorithm may be further compressed by Huffman coding. Huffman coding may be designed to search for repeated characters and perform compression again by assigning short codes for more frequent characters and long codes for less frequent characters. Huffman coding is prefix coding and is the best method of coding by which all codes are uniquely decodable.

Referring to fig. 2G, the transmitter side may encode the original data 2G-05 by using the LZ77 algorithm (2G-10), may update the buffer (2G-15), and may configure the UDC header by generating a checksum bit for the contents of the buffer (or data). The receiver side may use the checksum bits to determine whether the buffer status is valid.

The code encoded by using the LZ77 algorithm may be compressed again by using Huffman coding and may be transmitted as uplink data (2 g-25). The receiver side may perform a decompression process on the compressed data received from the transmitter side in a manner opposite to that of the transmitter side. That is, the receiver side may perform Huffman decoding (2g-30), may update the buffer (2g-35), and may determine whether the updated buffer is valid by using the checksum bits of the UDC header. When it is determined that the checksum bits have no errors, the receiver side may decompress the data (2g-40) by performing decoding using the LZ77 algorithm, may reconstruct the original data, and may deliver the decompressed data to an upper layer (2 g-45).

Because the LZ77 algorithm is a sliding window method, i.e., because previously encoded data is updated in a buffer and then encoding is immediately performed on the next data as described above, successive pieces of data may have a correlation therebetween. Therefore, only when previously encoded data is normally decoded, the next data can be normally decoded. Accordingly, the receiving PDCP layer may check the PDCP sequence number of the PDCP header, may check the UDC header (e.g., check an indicator indicating whether to perform data compression), and may perform a data decompression procedure on the compressed data in ascending order of the PDCP sequence number.

A procedure in which the gNB configures Uplink Data Compression (UDC) for the UE and a procedure in which the UE performs uplink data compression according to an embodiment of the present disclosure may be as follows.

Referring to fig. 2E, as shown in operations 2E-10, 2E-40, or 2E-75, the gNB may configure or release uplink data compression for logical channels or bearers that configure RLC AM mode in the UE through RRC messages. In addition, the gNB may reset a UDC entity (or protocol) of the PDCP layer of the UE by using an RRC message. When the gNB may reset the UDC entity (or protocol), this may mean that the gNB may reset the UDC buffer for uplink data compression by the UE in order to achieve synchronization between the UDC buffer of the UE and the UDC buffer for uplink data decompression by the gNB. In the operation of resetting the buffer of the UDC entity, a new PDCP control PDU may be defined, and the transmitter side (gNB) may reset the UDC buffer of the receiver side (UE) through the PDCP control PDU instead of the RRC message to achieve synchronization of user data compression and decompression between the transmitter side and the receiver side. In addition, whether to perform uplink data compression may be determined for each bearer, each logical channel, or each PDCP layer by using an RRC message. In more detail, whether to perform uplink data decompression can be configured for each IP flow (or QoS flow) in one bearer, logical channel, or PDCP layer by using the above-described message.

Further, using the RRC message, the gNB may configure a PDCP discard timer value in the UE. The PDCP discard timer value of the data in which the uplink data compression is not performed and the PDCP discard timer value of the data to which the uplink data compression is applied may be separately configured.

When the UE is configured to perform uplink data compression for a specific bearer, logical channel, or PDCP layer (or for QoS flow of the specific bearer, logical channel, or PDCP layer) by using the RRC message, the UE may reset a buffer in the UDC entity of the PDCP layer according to the configuration and may prepare an uplink data compression procedure. When data (PDCP SDU) is received from an upper layer, the UE may perform uplink data compression on the received data when the UE is configured to perform uplink data compression on the PDCP layer. When the UE is configured to perform uplink data compression for a specific QoS flow of the PDCP layer, the UE may determine whether to perform uplink data compression by checking an indication of an upper SDAP layer or a QoS flow identifier, and may perform uplink data compression. When performing Uplink Data Compression (UDC) and updating the buffer according to the uplink data compression, the UE may configure the UDC buffer. When Uplink Data Compression (UDC) is performed, PDCP SDUs received from an upper layer may be compressed into UDC data (UDC block) having a smaller size. The UE may configure a UDC header for the compressed UDC data. The UDC header may include an indicator indicating whether to perform or not perform uplink data compression (e.g., indicating that UDC is applied when the 1-bit indicator of the UDC header is 0 and not applied when the 1-bit indicator is 1).

The case where the uplink data compression is not applied may include a case where the PDCP SDU data structure received from the upper layer is not a duplicate data structure and thus data compression cannot be performed by using a UDC method (e.g., a DEFLATE algorithm).

When the UE performs Uplink Data Compression (UDC) on data (PDCP SDU) received from an upper layer and updates a UDC buffer, the PDCP layer at the receiver end may calculate a checksum bit to check validity of the updated UDC buffer, and may cause the calculated checksum bit to be included in the UDC buffer (the checksum bit may have a certain length, for example, 4 bits).

The transmitting PDCP layer may reset the transmitting UDC buffer, and may define and configure 1 bit in the UDC header 2i-02 of the first data of the UDC compression new application after the transmitting UDC buffer is reset to indicate the receiving PDCP layer to reset the receiving UDC buffer, and newly perform UDC decompression from the data in which the UDC header 2i-02 is configured with the reset receiving UDC buffer. For example, the PDCP layer may define an FR field such as 2I-05 of FIG. 2I. Further, the transmitting PDCP layer in which the UDC compression procedure is configured can indicate whether the UDC compression procedure is applied or not applied to data received from an upper layer by defining a 1-bit indicator (e.g., FU field 2i-10) of the UDC header 2 i-02.

The UE may perform ciphering on data with or without uplink data decompression applied, may perform integrity protection at configuration time, and may transfer data to lower layers.

Fig. 2H is a view for describing a decompression failure occurring in an uplink or downlink data compression method according to an embodiment of the present disclosure.

As described with reference to fig. 2G, an Uplink Data Compression (UDC) algorithm, for example, a DEFLATE algorithm (for performing an LZ77 algorithm and then huffman coding) may be a method of updating previously compressed data in a buffer when data compression is performed at a transmitter end, comparing the data with data to be compressed later based on the buffer, searching for a repetitive structure, and compressing the repetitive structure into a position and a length.

Therefore, even when the receiver side performs decompression, the receiver side may have to perform decompression in the same compression order as that performed at the transmitter side in order to successfully perform decompression. For example, when the transmitter side has performed UDC compression on data of PDCP sequence numbers 1, 3, 4, and 5 and has not performed UDC compression on data of PDCP sequence number 2 (2h-05), the receiver side may have to perform decompression on the received data in the order of PDCP sequence numbers 1, 3, 4, and 5 in the PDCP layer in order to successfully decompress.

When the transmitter side performs UDC compression, the receiver side can determine whether UDC compression has been applied by checking the UDC header because the UDC header indicates UDC compression. When data of PDCP sequence number 3(2h-15) is lost in performing a series of UDC decompression operations, all subsequent UDC decompression operations will fail. That is, the UDC decompression cannot be performed on the data of PDCP sequence numbers 4 and 5 (2 h-10). Therefore, lost data (packets) should not be generated during uplink decompression, and the receiver end may have to perform decompression in the same order as UDC compression performed at the transmitter end. Therefore, it may be necessary to use the RLC AM mode without loss and retransmission functions.

However, lost data may also be generated due to a PDCP discard timer of the PDCP layer. That is, the PDCP layer can drive a timer by using a PDCP discard timer value configured in an RRC message for each data (packet or PDCP SDU) received from a higher layer. When the timer expires, data corresponding to the timer is discarded. Thus, when the timer for the data on which UDC compression is performed expires, the data may be discarded and thus UDC decompression performed by the receiver end on a subsequent UDC compressed data segment may fail.

As described with reference to fig. 2G, according to an Uplink Data Compression (UDC) algorithm (e.g., DEFLATE algorithm (for performing LZ77 algorithm, then huffman coding)), the transmitter end may perform uplink data compression, then may generate checksum bits by using the current contents of the buffer, and may configure the UDC header. The transmitter side may update the buffer by using original data of the compressed data, may compare the data with data to be compressed later based on the buffer, may search for a repeated structure, and may compress the repeated structure into a position and a length. The checksum bit in the UDC header is used to determine the validity of the current buffer status before the UDC entity (or function) of the PDCP layer at the receiver end performs data decompression. That is, before the receiver side performs data decompression, the receiver side checks validity of a current UDC buffer of the receiver side by using checksum bits of a UDC header, and when there is no checksum error, the receiver side may perform data decompression, and when a checksum failure occurs, the receiver side may not perform data decompression, and may report the checksum failure to the transmitter side to restore data.

In the embodiments of the present disclosure, even when the receiver side performs decompression, the receiver side may have to perform decompression in the same compression order as that performed at the transmitter side in order to successfully perform decompression. For example, when the transmitter side has performed UDC compression on data of PDCP sequence numbers 1, 3, 4, and 5 and has not performed UDC compression on data of PDCP sequence number 2, the receiver side may have to perform decompression on the received data in the PDCP layer in the order of PDCP sequence numbers 1, 3, 4, and 5 in order to successfully decompress. When the transmitter side performs UDC compression, the receiver side can determine whether UDC compression has been applied by checking the UDC header because the UDC header indicates UDC compression. When a checksum failure of data of PDCP sequence number 3 occurs during the execution of a series of UDC decompression operations, all subsequent UDC decompression operations may fail. That is, the UDC decompression cannot be successfully performed on the data of PDCP sequence numbers 4 and 5.

Embodiments of the present disclosure may provide a checksum failure processing method that solves a checksum failure as follows.

Fig. 2I is a diagram for describing a PDCP control PDU format suitable for a checksum failure processing method according to an embodiment of the present disclosure.

In fig. 2I, the D/C field may be a field for identifying general data in the PDCP layer or PDCP layer control information (PDCP control PDU), and the PDU type field may be a field for indicating the type of PDCP layer control information. According to the checksum failure processing method of the embodiment of the present disclosure, for the feedback of, for example, 2i-01, a 1-bit indicator (FE field) indicating whether a checksum failure occurred or not may be defined and used. When the value of the 1-bit indicator is 0, it may indicate that UDC decompression is generally performed, and when the value of the 1-bit indicator is 1, it may indicate that checksum failure occurs during UDC decompression and a UDC buffer of the transmission PDCP layer is to be reset.

In an embodiment of the present disclosure, a new PDCP control PDU may be defined by assigning a reserved value (e.g., 011 or between 100 and 111) to a PDU type to define a 2i-01 format, and the PDCP control PDU with the defined PDU type may be used as feedback for indicating checksum failure.

[ Table 1]

Bit description

000 PDCP status report

001 inserted ROHC feedback packet

010 LWA status report

011 UDC checksum failure feedback

100-111 Retention

An embodiment of a checksum failure handling method using the PDCP control PDU of fig. 2I is as follows.

When the receiver side (e.g., a base station) checks the checksum of the receiving UDC buffer for data on which uplink data decompression is to be performed for failure, the receiver side can indicate that the checksum failure has occurred by transmitting a PDCP control PDU to the terminal. A new PDCP control PDU may be defined and used as the PDCP control PDU, or an existing PDCP control PDU may be changed and used as the PDCP control PDU by defining a new indicator in the changed existing PDCP control PDU. In another approach, instead of PDCP sequence numbers, indicators indicating that the UDC buffer is reset due to checksum failure may be defined to indicate checksum failure.

Operation at the receiver: when a checksum failure occurs, the receiver side can directly reset the receiving UDC buffer. The receiver end may reorder the newly received data segments based on the PDCP sequence numbers and may then check the UDC headers of the data segments in ascending order of the PDCP sequence numbers. In this case, when all of the plurality of data segments are received in the order of PDCP sequence numbers with no gap in ascending order of PDCP sequence numbers, because it is indicated that the transmitting UDC buffer has been reset due to the UDC checksum failure, the receiver end may discard the data segment which does not include the indicator indicating that the receiving UDC buffer has been reset and which has performed the UDC compression and process the data segment whose UDC header does not include the indicator indicating that the transmitting UDC buffer has been reset due to the UDC checksum failure and which has not performed the UDC compression, and deliver the processed data segment to the higher layer. According to data whose UDC header includes an indicator indicating that the transmitting UDC buffer has been reset due to a UDC checksum failure and that the receiving UDC buffer is to be reset, the receiver end may reset the receiving UDC buffer and may restart decompressing already compressed data segments in ascending order of PDCP sequence numbers.

Operation at the transmitter end: when a transmitter end (terminal) receives a PDCP control PDU, the transmitter end may reset a transmission UDC buffer, may discard a data segment (e.g., PDCP PDU) that has not been transmitted in a data segment on which UDC compression has been performed before resetting the transmission UDC buffer, may perform Uplink Data Compression (UDC) again on an original data segment (e.g., PDCP SDU) of the data segment that has not been transmitted based on the reset transmission UDC buffer, may update the UDC buffer, may include a checksum bit in the UDC header, performs ciphering on the UDC header and the data part, may generate a PDCP header, may configure the PDCP PDU, and may transfer the PDCP PDU to a lower layer.

Further, the transmitter end may include an indicator indicating that the transmission buffer has been reset or an indicator indicating that the reception buffer is reset in a UDC header or a PDCP header of the newly configured PDCP PDU and may transmit the PDCP PDU, and may newly allocate PDCP sequence numbers that have not been transmitted in an ascending order (i.e., when data encrypted using a PDCP count value and a security key and then transmitted is encrypted again using the same encrypted PDCP count value and security key and then retransmitted, a risk of hacking is increased, and thus the transmitter end may comply with a rule of performing one encryption and transmission with respect to one PDCP count value). In another method, when the transmitter side receives an indication indicating that checksum failure has occurred, the transmitter side may reset a transmission UDC buffer, may perform new UDC compression only on PDCP PDUs to be newly configured or data whose PDCP sequence number is equal to or greater than a PDCP sequence number of data that has not been transferred to a lower layer, and may transfer the data to the lower layer. Further, the transmitter side may include an indicator indicating that the transmission UDC buffer has been reset (or an indicator indicating that the reception UDC buffer is reset) in a PDCP header or a UDC header of the newly configured PDCP PDU, and may transfer data (i.e., when data that is ciphered using a PDCP count value and a security key and then transmitted is ciphered again using the same PDCP count value and security key and then retransmitted, a risk of hacking is increased, and thus the transmitter side may comply with a rule of performing ciphering and transmission once with respect to one PDCP count value).

However, a checksum failure may occur due to a PDCP discard timer of the PDCP layer. That is, the PDCP layer can drive a timer by using a PDCP discard timer value configured in an RRC message for each data (packet or PDCP SDU) received from a higher layer. When the timer expires, data corresponding to the timer may be discarded. Thus, when the timer for the data on which UDC compression is performed expires, a portion of the UDC compressed data may be discarded, and thus UDC decompression performed by the receiver end on a subsequent UDC compressed data segment may fail.

The first embodiment can be provided to prevent data loss when data on which UDC compression has been performed is discarded due to a PDCP discard timer in a transmitting PDCP layer, and to reduce data of checksum failure in a receiver side.

Operation at the transmitter end: when an uplink data compression procedure is configured and data that has not been transmitted and has been subjected to UDC compression is discarded due to expiration of the PDCP discard timer, the transmitting PDCP layer may transmit data whose PDCP sequence number is greater than that of the discarded data and on which UDC compression has been performed, and may discard all remaining data (e.g., data whose PDCP sequence number is greater than the next PDCP sequence number of the discarded data, on which user data compression has been performed, and which is stored without being transmitted). In addition, the transmitting PDCP layer may transmit an indicator for discarding data to a lower layer when the data has been transferred to the lower layer. The transmitting PDCP layer may stop data transmission until receiving a PDCP control PDU indicating that a checksum failure has occurred. This is because, apparently, since part of the UDC compressed data or intermediate sequence numbers corresponding to sequence numbers or data is discarded, checksum failure may occur in the receiving PDCP layer for data (e.g., PDCP PDUs) whose user data compression has been performed and whose PDCP sequence number is greater than the PDCP sequence number of the discarded data. Accordingly, it can be expected that the receiving PDCP layer checks that the checksum has failed and transmits the PDCP control PDU when transmitting data corresponding to the next PDCP sequence number of the discarded data.

Accordingly, the transmitting PDCP layer may reset a transmitting UDC buffer for user data compression upon or before receiving a PDCP control PDU indicating that checksum failure has occurred (or may not reset the transmitting UDC buffer in the case where the transmitting UDC buffer has been reset), may apply a user data compression procedure again from original data (e.g., PDCP SDU) of data whose PDCP discard timer has not expired and which has not been transmitted, or from original data (e.g., PDCP SDU) of data whose PDCP discard timer has not expired and which was transmitted last (transmission data corresponding to the next PDCP sequence number of discarded data), if necessary, and may encrypt data (e.g., PDCP PDU) in ascending order from a new PDCP sequence number or the first PDCP sequence number which has not been transmitted, Generation and preparation. After receiving the PDCP control PDU indicating that the checksum failure has occurred, the transmitting PDCP layer may restart transmission of newly generated and prepared data (e.g., PDCP PDUs). That is, the transmitting PDCP layer may transfer data to a lower layer.

In an embodiment of the present disclosure, the PDCP SDU may indicate original data received by the transmitting PDCP layer from a higher layer, and the PDCP PDU may indicate data to be transmitted to a lower layer after being processed by the transmitting PDCP layer data. The data processing may include header compression, user layer data compression, ciphering, or integrity protection and verification configured in the PDCP layer. Further, the PDCP PDU generated by data processing of the PDCP SDU may be data different from the PDCP SDU, and the PDCP SDU may be stored even if discarded, and may be discarded only by the PDCP data discard timer.

Therefore, when the user data compression procedure is configured, when a portion of data that has been previously generated and has been subjected to user data compression is discarded due to the PDCP discard timer, since data is regenerated from data that has not been transmitted or from data that was transmitted last (transmission data corresponding to the next PDCP sequence number at which data is discarded), checksum failures that may occur in data whose PDCP sequence number is greater than that of the discarded data can be reduced, and data loss can be prevented,

when the receiving end (base station) checks the checksum of the receiving UDC buffer for data for which uplink data decompression is to be performed fails, the receiving end can indicate that a checksum failure has occurred by sending PDCP control PDU to the terminal. A new PDCP control PDU may be defined and used as a PDCP control PDU, or an existing PDCP control PDU may be changed and used as a PDCP control PDU by defining a new indicator in the changed existing PDCP control PDU. In another approach, instead of PDCP sequence numbers, indicators for resetting the UDC buffer due to checksum failures may be defined to indicate checksum failures.

-operations at the receiver: when checksum failure occurs, the receiver side can directly reset the UDC buffer. The receiver end may reorder the newly received data segments based on the PDCP sequence numbers and may then check the UDC headers of the data segments in ascending order of the PDCP sequence numbers. In this case, when all of the plurality of data segments are received in the order of PDCP sequence numbers with no gap in ascending order of PDCP sequence numbers, because it is indicated that the transmitting UDC buffer has been reset due to the UDC checksum failure, the receiver end may discard the data segment which does not include the indication for resetting the receiving UDC buffer and which has performed the UDC compression, and may process the data segment whose UDC header does not include the indicator indicating that the transmitting UDC buffer has been reset due to the UDC checksum failure and which has not performed the UDC compression, and deliver the processed data segment to a higher layer. Based on data whose UDC header includes an indicator that indicates that the sending UDC buffer has been reset and that the receiving UDC buffer is to be reset due to a UDC checksum failure, the receiver end may reset the receiving UDC buffer and may restart decompressing already compressed data segments in ascending order of PDCP sequence numbers.

A second embodiment may be provided for preventing data loss when data on which UDC compression has been performed is discarded due to a PDCP discard timer in a transmitting PDCP layer, and reducing data of checksum failure in a receiver side.

To solve these problems, in the second embodiment, when first data which has not been transmitted and has been subjected to UDC compression is discarded due to expiration of the PDCP discard timer, the transmitting PDCP layer in which the UDC compression procedure is configured may discard the first data, and may discard all second data (e.g., PDCP PDUs) which has been UDC compressed and stored, whose PDCP sequence number is greater than that of the first data and which has not been transmitted. This is because when one of the data to which UDC compression is continuously applied is lost, UDC decompression failure may occur for the data to which UDC compression is applied after the discarded data in the receiving PDCP layer, and all the data may be discarded.

After discarding the first data, the transmitting PDCP layer may prepare a new UDC compression procedure by resetting the transmitting UDC buffer. When the UDC buffer can be reset, it can be indicated that the values of the UDC buffer are all reset to 0. In another method, when predetermined information (predetermined dictionary) is configured in the RRC message, it may be instructed to input the predetermined information and reset it to a value of the UDC buffer.

Since the transmitting PDCP layer has not transmitted original data (e.g., PDCP SDUs) of the second data (e.g., PDCP PDUs) after the transmitting UDC buffer reset, the transmitting PDCP layer can re-apply the UDC compression procedure to the original data (e.g., PDCP SDUs, or original data received from a higher layer without applying data processing in the PDCP layer) of the second data by using the reset transmitting UDC buffer. Each UDC header may be generated and configured and then data transfer may be performed by applying encryption or integrity protection.

Further, the transmitting PDCP layer may instruct resetting of a receiving UDC buffer of the receiving PDCP layer by using a 1-bit indicator in a UDC header of first data (PDCP PDU) to which a UDC compression procedure is first applied to perform data processing after resetting of the transmitting UDC buffer. This is because the receiving PDCP layer may not know which data UDC compression is newly performed after the transmitting UDC is reset, and thus the transmitting PDCP layer may indicate the data by using a 1-bit indicator of the UDC buffer, so that the receiving PDCP layer checks the 1-bit indicator, resets the receiving UDC buffer, and performs a UDC decompression process by using the reset receiving UDC buffer from the data. Accordingly, when a 1-bit indicator in a UDC header of received data (e.g., PDCP PDU) may indicate that a receiving UDC buffer is reset, the receiving PDCP layer may know that a transmitting UDC buffer has been reset and that new UDC compression has been applied to the data. Accordingly, the receiving PDCP layer may reset the receiving UDC buffer and may apply a UDC decompression procedure by using the reset receiving UDC buffer from the data.

According to the second embodiment of the present disclosure, when a user data compression procedure is configured, when a portion of data that has been previously generated and has been performed user data compression is discarded due to a PDCP discard timer, since data whose PDCP sequence number is greater than that of the discarded data and UDC compression is applied is not transmitted, decompression failure or checksum failure that may occur in a receiving PDCP layer may be reduced, and waste of transmission resources may be reduced. In addition, since data is regenerated from unsent data or from last transmitted data (transmitted data corresponds to the next PDCP sequence number to discard data), data loss can be prevented.

Further, since the transmitting PDCP layer can immediately reset the transmitting UDC buffer and can restart the UDC compression without waiting for PDCP control data (PDCP control PDU) for resetting the transmitting UDC buffer transmitted from the receiving PDCP layer due to the checksum failure, the transmission latency can be reduced. Since no checksum failure or decompression failure occurs in the receiving PDCP layer, the receiving PDCP layer may not need to generate and transmit PDCP control data, and may reset the receiving UDC buffer and newly start UDC decompression according to a 1-bit indicator of the UDC header indicated in the transmitting PDCP layer. Accordingly, a second embodiment of the present disclosure may be a terminal-based transmission/reception UDC buffer resetting method using a 1-bit indicator of a UDC header.

The detailed operation of the second embodiment of the present disclosure is as follows.

-operation at the transmitter end: when the uplink data compression procedure is configured and data that has not been transmitted and has been subjected to UDC compression is discarded due to expiration of the PDCP discard timer, the transmitting PDCP layer may discard all data (e.g., PDCP PDUs) whose PDCP sequence number is greater than that of the discarded data, or PDCP PDUs that have been generated as PDCP PDUs to which user data compression is applied and stored without being transmitted. In addition, the transmitting PDCP layer may transmit an indicator of discarding data to a lower layer when data has been transferred to the lower layer. The transmitting PDCP layer may reset a buffer for user data compression (UDC buffer), may assign PDCP sequence numbers to data starting from original data (e.g., PDCP SDUs) of first data that has not been transmitted, may perform user data compression again in ascending order from a new PDCP sequence number or PDCP sequence numbers that have not been transmitted, and may perform ciphering. Further, when the UDC header of the first data to which the UDC compression is first applied after the transmission UDC buffer is reset is generated, in order to indicate that the transmission buffer for user data compression has been reset or to indicate that the reception UDC buffer at the receiver end is reset, the transmission PDCP layer may define and indicate a new 1-bit indicator (e.g., 2I-05 of fig. 2I). When the receiver side checks the 1-bit indicator of the UDC header, the receiver side can know that the receive buffer for user data decompression may have to be reset. In another approach, the FR bit may be used to indicate that the transmit buffer for user data compression has been reset, and the receiver side may indicate that the receive buffer for user data decompression may have to be reset. That is, the terminal may reset the transmission and reception UDC buffer.

The transmitting PDCP layer can immediately start transmitting newly generated and prepared data from data whose UDC header indicates that the transmission buffer for user data compression has been reset and whose reception buffer for data decompression is reset by the receiver side, sequentially or in ascending order of PDCP sequence numbers. That is, the transmitting PDCP layer may transfer data to a lower layer.

According to a second embodiment, the terminal itself can trigger the procedure of resetting the sending and receiving UDC buffers before checksum failure by using the 1-bit indicator of the UDC header. Accordingly, when the user data compression procedure is configured, when a portion of data that has been previously generated and whose user data compression has been performed is discarded due to the PDCP discard timer, since data is regenerated from data that has not been transmitted, checksum failures that may occur in data whose PDCP sequence number is greater than that of the discarded data can be reduced, and data loss can be prevented.

Operation at the receiver: when the UDC header of the received data indicates that the transmission buffer for user data compression has been reset and even the receiving side indicates that the reception buffer for user data decompression may have to be reset, the receiver side may reset the reception UDC buffer, may perform decryption and user data decompression on the received data in ascending order of PDCP sequence numbers, and may deliver the data to a higher layer.

Embodiments of the present disclosure may provide efficient detailed operation of the transmitting and receiving PDCP layers of a bearer in which a user data compression process (uplink data compression or downlink data compression) is configured.

A first embodiment of an efficient operation of the transmitting and receiving PDCP layers of the bearer in which the user data compression procedure is configured is as follows. For example, the operation of the transmitting PDCP layer of the terminal or the base station according to the embodiment of the present disclosure is as follows.

The transmitting PDCP layer may use a first count variable that maintains a count value to be assigned to data to be transmitted NEXT during data processing, and the first count variable may be referred to as TX _ NEXT.

The operation of the transmitting PDCP layer of the present disclosure is as follows.

The transmitting PDCP layer may operate a PDCP data discard timer when data (e.g., PDCP SDUs) is received from a higher layer, and may discard the data when the PDCP data discard timer expires.

The transmitting PDCP layer may assign a count value corresponding to TX _ NEXT to data received from a higher layer. The initial value TX _ NEXT may be set to 0, and TX _ NEXT may maintain a count value of data to be transmitted NEXT (PDCP SDU).

When a header compression protocol (ROHC) is configured in the transmitting PDCP layer, the transmitting PDCP layer may perform header compression on data.

When a user data compression protocol (uplink data compression/downlink data compression (UDC/DDC)) is configured in a transmitting PDCP layer

1. When user data compression may be applied to data received from a higher layer, the transmitting PDCP layer may generate a user data compression header (UDC header or DDC header) and may configure a 1-bit indicator in the user data compression header indicating that user data compression has been applied to the data, and when user data compression is not applied to the data, the transmitting PDCP layer may generate a user data compression header and may configure a 1-bit indicator in the user data compression header indicating that user data compression has not been applied. When user data compression is applied, the transmitting PDCP layer may apply compression to the data.

2. When an error indicating that checksum failure has occurred is received from a receiving PDCP layer at a receiver, the transmitting PDCP layer may reset a transmitting user data compression buffer (UDC/DDC buffer) of a user data compression protocol, and may indicate data compressed first after resetting the transmitting user data compression buffer by using a 1-bit indicator in a user data compression header of first data to which user data compression is newly applied.

3. When the transmission user data compression buffer needs to be reset due to a PDCP discard timer or a protocol error, the transmission PDCP layer of the transmission end may reset the transmission user data compression buffer and may indicate data compressed first after the transmission user data compression buffer is reset by using a 1-bit indicator in a user data compression header of first data to which user data compression is newly applied. In addition, the transmitting PDCP layer may instruct the resetting of the receiving user data compression buffer of the receiving PDCP layer at the receiver end by using the indicator.

When integrity protection is configured in the transmitting PDCP layer, the transmitting PDCP layer may generate a PDCP header and may perform integrity protection on the PDCP header and data by using a security key and a count value assigned to TX _ NEXT of the data.

The transmitting PDCP layer may perform a ciphering process on data by using a security key and a count value assigned to TX _ NEXT of the data. The transmitting PDCP layer may configure a Least Significant Bit (LSB) of a PDCP sequence number length from a count value of TX _ NEXT to the PDCP sequence number. The transmitting PDCP layer may also cipher a user data compression header (UDC header/DDC header) in a ciphering process.

The transmitting PDCP layer may increase a count value of TX _ NEXT by 1, may combine the processed data with a PDCP header, and may transfer the data to a lower layer together with the PDCP header.

The operation of the receiving PDCP layer of the terminal or the base station according to the embodiment of the present disclosure is as follows.

The receiving PDCP layer may use a PDCP sequence number length (e.g., 12 bits or 18 bits) configured in RRC by the base station, may check a PDCP sequence number of received data (e.g., PDCP PDUs), and may drive a reception window. The receive window is set to half the size of the PDCP sequence number space (e.g., 2^ (PDCP SN length-1)) and is used to identify valid data. That is, the receiving PDCP layer may determine data received outside the reception window as invalid data and may discard the data. The reason why the data arrives outside the reception window is that the data arrives very late due to the RLC layer retransmission or the HARQ retransmission of the MAC layer from the lower layer. In addition, the receiving PDCP layer may drive a PDCP t-reordering timer and a receive window.

The PDCP t-reordering timer may be triggered when a PDCP sequence number gap occurs based on a PDCP sequence number in the receiving PDCP layer. When data corresponding to the PDCP sequence number gap does not arrive until the PDCP t-reordering timer expires, the receiving PDCP layer may transfer the data to a higher layer in an ascending order of the count value or the PDCP sequence number, and may move the reception window. Therefore, when data corresponding to the PDCP sequence number gap arrives after the PDCP t-reordering timer expires, the data is not data within the reception window, and thus the receiving PDCP layer can discard the data.

The specific procedure for receiving the PDCP layer is as follows. That is, the operation of the receiving PDCP layer of the terminal or the base station according to the present disclosure is as follows.

The receiving PDCP layer may maintain and manage three count variables in processing the received data. The receiving PDCP layer may use a second count value that maintains a count value of NEXT expected received data (e.g., PDCP SDUs) when processing the received data, and the second count variable may be referred to as RX _ NEXT. The receiving PDCP layer may use a third count value that maintains a count value of first data (e.g., PDCP SDUs) that is not delivered to a higher layer when processing the received data, and the third count variable may be referred to as RX _ DELIV. The receiving PDCP layer may use a fourth count variable that maintains a count value of data (e.g., PDCP SDUs) that triggers a PDCP t-reordering timer when processing the received data, and the fourth count variable may be referred to as RX _ REORD. The receiving PDCP layer may use a fifth COUNT variable that maintains a COUNT value of data (e.g., PDCP SDUs) currently received while processing the received data, and the fifth COUNT variable may be referred to as RCVD _ COUNT. The PDCP t-reordering timer may use a timer value or interval configured in an RRC message in a higher layer (RRC layer) as described with reference to fig. 1E. The PDCP t-reordering timer may be used to detect missing PDCP PDUs and only run one timer at a time.

In addition, a terminal in operation of receiving the PDCP layer may define and use the following variables.

-an HFN: a Hyper Frame Number (HFN) indicating a window state variable.

-SN: a Sequence Number (SN) indicating a window state variable.

-RCVD _ SN: indicating a PDCP sequence number included in a header of the received PDCP PDU.

-RCVD _ HFN: indicating the HFN value of the received PDCP PDU calculated by the receiving PDCP layer.

When receiving the PDCP PDU from the lower layer, the receiving PDCP layer may determine a count value of the received PDCP PDU as follows.

When RCVD _ SN ≦ SN (RX _ DELIV) -window size is received, equation 1 may result:

RCVD _ HFN ═ HFN (RX _ DELIV) +1 (equation 1).

On the other hand, when RCVD _ SN is RCVD _ SN > SN (RX _ DELIV) + window size, equation 2 may result in:

RCVD _ HFN ═ HFN (RX _ DELIV) -1 (equation 2).

In other cases, equation 3 may result in:

RCVD _ HFN ═ HFN (RX _ DELIV) (equation 3).

The RCVD _ COUNT may be determined as RCVD _ COUNT ═ RCVD _ HFN, RCVD _ SN.

After determining the count value of the received PDCP PDU, the receiving PDCP layer may update a window state variable as follows, and may process the PDCP PDU.

The receiving PDCP layer may perform deciphering on the PDCP PDUs by using the RCVD _ COUNT value and may perform integrity verification.

1. When the integrity verification fails, the receiving PDCP layer may indicate the integrity verification failure to a higher layer and may discard the received PDCP data PDUs (data parts of the PDCP PDUs).

When RCVD _ COUNT < RX _ DELIV, or when a PDCP PDU with RCVD _ COUNT value has been received previously (packet outdated, outdated or outside of window, or duplicate packet case) (when integrity protection is configured and the PDCP PDU with RCVD _ COUNT value succeeds in previous integrity protection).

1. The receiving PDCP layer may discard the received PDCP data PDU (data part of the PDCP PDU).

When the received PDCP PDU is not discarded, the receiving PDCP layer may operate as follows.

The receiving PDCP layer may store the processed PDCP SDUs in a reception buffer.

-when RCVD _ COUNT > -RX _ NEXT,

RX _ NEXT can be updated to RCVD _ COUNT + 1.

When an out-of-order delivery indicator (outOfOrderDelivery) is configured (out-of-order delivery operation is indicated),

1. the receiving PDCP layer may deliver PDCP SDUs to higher layers.

When RCVD _ COUNT is the same as RX _ DELIV

1.- (despite the configuration of the user data compression protocol (UDC/DDC) or the header compression protocol (e.g. ROHC)), when the header decompression process has not been applied previously (i.e. when compression has not been performed on higher layer headers or data)

A. When a user data compression protocol is configured and user data has been compressed (when an indicator of a user data compression header is checked and indicates that user data has been compressed)

i. When the user data compression header may indicate that the sending UDC buffer has been reset and may indicate that the first data of the user data compression is to be applied newly (by checking the FR bit).

A) The receiving PDCP layer may reset the receiving user data compression protocol buffer.

B) When the checksum field of the user data compressed header is checked, the checksum checking process is performed, and a checksum error does not occur,

the receiving PDCP layer may perform decompression on the data.

C) Otherwise, when the checksum field of the user data compressed header is checked, a checksum checking process is performed, and a checksum error occurs,

the receiving PDCP layer may discard data and may generate PDCP control PDUs and transmit the PDCP control PDUs to the transmitting PDCP layer at the transmitter end to indicate that a checksum error has occurred. The receiving PDCP layer may instruct the lower layer to discard data (e.g., PDCP PDUs) previously generated and transferred to the lower layer, and the lower layer may discard data that has not been transmitted. The receiving PDCP layer may not generate additional PDCP control PDUs until data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied is received from among subsequently received data by using the 1-bit indicator of the user data compression header, and thus unnecessary PDCP control PDU transmission may be prevented.

(iii) the receiving PDCP layer may discard all data to which the user data compression process is applied, among data whose count value or PDCP sequence number is smaller than that of data indicating that the transmission user data compression buffer has been reset and indicating that the first data to which the user data compression is newly applied by using the 1-bit indicator of the user data compression header, among subsequently received data.

On the other hand, when the user data compression header does not indicate that the sending UDC buffer has been reset and does not indicate the first data to which user data compression is newly applied (by checking the FR bit)

A) When the checksum field of the user data compressed header is checked, the checksum checking process is performed, and a checksum error does not occur,

the receiving PDCP layer may perform decompression on the data.

B) Otherwise, when the checksum field of the user data compressed header is checked, a checksum checking process is performed, and a checksum error occurs,

B. When the user data compression protocol is configured and the user data is not compressed (when an indicator of the user data compression header may be checked and the indicator may indicate that the user data is not compressed),

i. the receiving PDCP layer may not perform decompression on the data and may remove the user data compression header.

C. On the other hand, when the user data compression protocol is not configured and the header compression protocol (e.g., ROHC) is configured,

i. the receiving PDCP layer may perform decompression on a higher layer header (TCP/IP or UDP header) of the data.

2. The receiving PDCP layer may transfer data to a higher layer in order of the count value.

A. The receiving PDCP layer may deliver all consecutive PDCP SDUs from COUNT RX _ DELIV to the higher layer.

3. The receiving PDCP layer may update RX _ DELIV to a count value of a first PDCP SDU not delivered to the higher layer, wherein the count value is equal to or greater than the current RX _ DELIV.

-when the t-reordering timer is running and RX _ DELIV is equal to or greater than RX _ REORD,

1. the receiving PDCP layer may stop and reset the t-reordering timer.

When the t-reorder timer is not running (including the case of stopping the t-reorder timer under the above conditions) and RX _ DELIV is less than RX _ NEXT,

1. the receiving PDCP layer may update RX _ REORD to RX _ NEXT.

2. The receiving PDCP layer may start a t-reordering timer.

When the PDCP t-reordering timer expires, the receiving PDCP layer may operate as follows.

- (despite the configuration of the user data compression protocol (UDC/DDC) or the header compression protocol (e.g. ROHC)), when the header decompression procedure has not been applied before (i.e. when no compression has been performed on the higher layer headers or data)

1. When a user data compression protocol is configured and user data has been compressed (when an indicator of a user data compression header is checked and indicates that user data has been compressed)

A. When a checksum field of a user data compressed header is checked, a checksum checking process is performed, and a checksum error does not occur

i. The receiving PDCP layer may perform decompression on the data.

B. Otherwise, when the checksum field of the user data compression header is checked, a checksum checking process is performed, and a checksum error occurs.

i. The receiving PDCP layer may discard data and may generate PDCP control PDUs and send the PDCP control PDUs to the transmitting PDCP layer at the transmitter to indicate that a checksum error has occurred. The receiving PDCP layer may instruct the lower layer to discard data (e.g., PDCP PDUs) previously generated and transferred to the lower layer, and the lower layer may discard data that has not been transmitted. The receiving PDCP layer may not generate additional PDCP control PDUs until data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied is received from among subsequently received data by using the 1-bit indicator of the user data compression header, and thus unnecessary PDCP control PDU transmission may be prevented.

The receiving PDCP layer may discard all data to which the user data compression process is applied, among data whose count value or PDCP sequence number is less than the count value or PDCP sequence number of data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied, by using the 1-bit indicator of the user data compression header, among subsequently received data.

2. When the user data compression protocol is configured and the user data is not compressed (when an indicator of the user data compression header may be checked and the indicator may indicate that the user data is not compressed),

A. The receiving PDCP layer may not perform decompression on the data and may remove the user data compression header.

3. On the other hand, when the user data compression protocol is not configured and the header compression protocol (e.g., ROHC) is configured,

A. the receiving PDCP layer may perform decompression on a higher layer header (TCP/IP or UDP header) of the data.

-the receiving PDCP layer delivering data to the higher layer in the order of the count value.

1. The receiving PDCP layer may deliver all PDCP SDUs having a count value less than RX _ REORD.

2. The receiving PDCP layer may deliver all PDCP SDUs having consecutive count values from RX _ REORD.

The receiving PDCP layer may update RX _ DELIV to a count value of the first PDCP SDU not transmitted to the higher layer, wherein the count value is equal to or greater than RX _ REORD.

-when RX _ DELIV is less than RX _ NEXT,

1. the receiving PDCP layer may update RX _ REORD to RX _ NEXT.

2. The receiving PDCP layer may start a t-reordering timer.

When the PDCP t-reordering timer expires, another receiving PDCP layer according to an embodiment of the present disclosure may operate as follows.

1. When the user data compression protocol is configured and the user data has been compressed (when the indicator of the user data compression header is checked and the indicator indicates that the user data has been compressed),

A. the receiving PDCP layer may discard data and may generate PDCP control PDUs and send the PDCP control PDUs to the transmitting PDCP layer at the transmitter to indicate that a checksum error has occurred. The receiving PDCP layer may instruct the lower layer to discard data (e.g., PDCP PDUs) previously generated and transferred to the lower layer, and the lower layer may discard data that has not been transmitted. The receiving PDCP layer may not generate additional PDCP control PDUs until data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied is received from among subsequently received data by using the 1-bit indicator of the user data compression header, and thus unnecessary PDCP control PDU transmission may be prevented.

B. The receiving PDCP layer may discard all data to which the user data compression process is applied, among data whose count value or PDCP sequence number is less than the count value or PDCP sequence number of data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied, by using the 1-bit indicator of the user data compression header, among subsequently received data.

The receiving PDCP layer may update RX _ DELIV to a count value of a first PDCP SDU not transmitted to the higher layer, wherein the count value is equal to or greater than RX _ REORD.

-when RX _ DELIV is less than RX _ NEXT,

1. the receiving PDCP layer may update RX _ REORD to RX _ NEXT.

2. The receiving PDCP layer may start a t-reordering timer.

A. the receiving PDCP layer may discard the data.

2. When the user data compression protocol is configured and the user data has not been compressed (when the indicator of the user data compression header is checked and the indicator indicates that the user data has not been compressed)

The receiving PDCP layer may deliver data to the higher layer in the order of the count value.

-when RX _ DELIV is less than RX _ NEXT,

1. the receiving PDCP layer may update RX _ REORD to RX _ NEXT.

2. The receiving PDCP layer may start a t-reordering timer.

A second embodiment of an efficient operation of the transmitting and receiving PDCP layers of the bearer in which the user data compression procedure is configured is as follows. That is, the operation of the transmitting PDCP layer of the terminal or the base station according to the embodiment of the present disclosure is as follows.

The receiving PDCP layer may use a PDCP sequence number length (e.g., 12 bits or 18 bits) configured in RRC by the base station, may check a PDCP sequence number of received data (e.g., PDCP PDUs), and may drive a reception window. The receive window may be set to half the size of the PDCP sequence number space (e.g., 2^ (PDCP SN length-1)) and may be used to identify valid data. That is, the receiving PDCP layer may determine data received outside the reception window as invalid data and may discard the data. The reason why the data arrives outside the reception window is that the data arrives very late due to the RLC layer retransmission or the HARQ retransmission of the MAC layer from the lower layer. In addition, the receiving PDCP layer may drive a PDCP t-reordering timer and a receive window.

The PDCP reordering timer may be triggered when a PDCP sequence number gap occurs in the receiving PDCP layer based on the PDCP sequence number. When data corresponding to the PDCP sequence number gap does not arrive until the PDCP t-reordering timer expires, the receiving PDCP layer may transfer the data to a higher layer in an ascending order of the count value or the PDCP sequence number, and may move the reception window. Therefore, when data corresponding to the PDCP sequence number gap arrives after the PDCP t-reordering timer expires, the data is not data within the reception window, and thus the receiving PDCP layer can discard the data.

A specific procedure of receiving the PDCP layer according to an embodiment of the present disclosure is as follows. That is, the operation of the receiving PDCP layer of the terminal or the base station according to the embodiment of the present disclosure is as follows.

The receiving PDCP layer may maintain and manage three count variables in processing the received data. The receiving PDCP layer may use a second count value that maintains a count value of NEXT expected received data (e.g., PDCP SDUs) when processing the received data, and the second count variable may be referred to as RX _ NEXT. The receiving PDCP layer may use a third count value that maintains a count value of first data (e.g., PDCP SDUs) that is not delivered to a higher layer when processing the received data, and the third count variable may be referred to as RX _ DELIV. The receiving PDCP layer may use a fourth count variable that maintains a count value of data (e.g., PDCP SDUs) that triggers a PDCP-t reordering timer when processing the received data, and the fourth count variable may be referred to as RX _ REORD. The receiving PDCP layer may use a fifth COUNT variable that maintains a COUNT value of data (e.g., PDCP SDUs) currently received while processing the received data, and the fifth COUNT variable may be referred to as RCVD _ COUNT. The PDCP reordering timer may use a timer value or interval configured in an RRC message in a higher layer (RRC layer) as described with reference to fig. 1E. The PDCP t-reordering timer may be used to detect missing PDCP PDUs and only run one timer at a time.

-an HFN: a Hyper Frame Number (HFN) indicating a window state variable.

-SN: a Sequence Number (SN) indicating a window state variable.

The operation of the receiving PDCP layer of the terminal or the base station according to the embodiment of the present disclosure is as follows. When receiving the PDCP PDU from the lower layer, the receiving PDCP layer may determine a count value of the received PDCP PDU as follows.

RCVD _ HFN ═ HFN (RX _ DELIV) +1 (equation 1).

On the other hand, when RCVD _ SN > SN (RX _ DELIV) + window size, equation 2 may result in:

RCVD _ HFN ═ HFN (RX _ DELIV) -1 (equation 2).

In other cases, equation 3 may result in:

RCVD _ HFN ═ HFN (RX _ DELIV) (equation 3).

The RCVD _ COUNT may be determined as RCVD _ COUNT ═ RCVD _ HFN, RCVD _ SN.

1. When the integrity verification fails, the integrity verification is performed,

the receiving PDCP layer may indicate integrity verification failure to higher layers and may discard the received DPCP data PDUs (data portion of PDCP PDUs).

-when RCVD _ COUNT > -RX _ NEXT,

RX _ NEXT can be updated to RCVD _ COUNT + 1.

1. the receiving PDCP layer may deliver PDCP SDUs to higher layers.

When RCVD _ COUNT is the same as RX _ DELIV

i. When the user data compression header may indicate that the sending UDC buffer has been reset and may indicate the first data for which user data compression is to be newly applied (by checking the FR bit).

the receiving PDCP layer may perform decompression on the data.

A) When the checksum field of the user data compressed header is checked, a checksum checking process is performed, and a checksum error does not occur.

The receiving PDCP layer may perform decompression on the data.

B. When the user data compression protocol is configured and the user data is not compressed (when the user data compression header can be checked and the indicator can indicate that the user data is not compressed),

3. The receiving PDCP layer may update RX _ DELIV to a count value of a first PDCP SDU not transmitted to the higher layer, wherein the count value is equal to or greater than the current RX _ DELIV.

1. the receiving PDCP layer may stop and reset the t-reordering timer.

1. the receiving PDCP layer may update RX _ REORD to RX _ NEXT.

2. The receiving PDCP layer may start a t-reordering timer.

A. When the user data compression header may indicate that the sending UDC buffer has been reset and may indicate the first data for which user data compression is to be newly applied (by checking the FR bit),

i. the receiving PDCP layer may reset the receiving user data compression protocol buffer.

When the checksum field of the user data compression header is checked, a checksum checking process is performed, and a checksum error does not occur,

the receiving PDCP layer may perform decompression on the data.

Otherwise, when the checksum field of the user data compressed header is checked, a checksum checking process is performed, and a checksum error occurs.

A) The receiving PDCP layer may discard data and may generate PDCP control PDUs and send the PDCP control PDUs to the transmitting PDCP layer at the transmitter to indicate that a checksum error has occurred. The receiving PDCP layer may instruct the lower layer to discard data (e.g., PDCP PDUs) previously generated and transferred to the lower layer, and the lower layer may discard data that has not been transmitted. The receiving PDCP layer may not generate additional PDCP control PDUs until data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied is received from among subsequently received data by using the 1-bit indicator of the user data compression header, and thus unnecessary PDCP control PDU transmission may be prevented.

B) The receiving PDCP layer may discard all data to which the user data compression process is applied, among data whose count value or PDCP sequence number is less than the count value or PDCP sequence number of data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied, by using the 1-bit indicator of the user data compression header, among subsequently received data.

B. On the other hand, when the user data compression header does not indicate that the sending UDC buffer has been reset and does not indicate the first data to which user data compression is newly applied (by checking the FR bit).

i. When the checksum field of the user data compression header is checked, a checksum checking process is performed, and a checksum error does not occur.

A) The receiving PDCP layer may perform decompression on the data.

Else, when checking the checksum field of the user data compressed header, performing a checksum checking process, and generating a checksum error,

2. When the user data compression protocol is configured and the user data is not compressed (when an indicator of the user data compression header may be checked and may indicate that the user data is not compressed),

-when RX _ DELIV is less than RX _ NEXT,

1. the receiving PDCP layer may update RX _ REORD to RX _ NEXT.

2. The receiving PDCP layer may start a t-reordering timer.

Fig. 2J is a diagram for describing an operation of a terminal receiving a PDCP layer according to an embodiment of the present disclosure.

In operation 2j-05, the receiving PDCP layer of the terminal may receive data from the lower layer.

In operations 2j-10 and 2j-20, the receiving PDCP layer may reset the receiving user data compression protocol buffer in operation 2j-25 when the user data compression protocol (UDC/DDC) is configured and the user data has been compressed (when the indicator of the user data compression header is checked and indicates that the user data has been compressed), and when the user data compression header may indicate that the transmitting UDC buffer has been reset and may indicate the first data to which user data compression is newly applied (by checking the FR bit). When the checksum field of the user data compression header is checked, the checksum checking process is performed, and the checksum error does not occur in operation 2j-30, the receiving PDCP layer may perform decompression on the data in operation 2 j-35. Otherwise, when the checksum field of the user data compression header is checked, a checksum checking procedure is performed, and a checksum error occurs, the receiving PDCP layer may discard data and may generate PDCP control PDUs and transmit the PDCP control PDUs to the transmitting PDCP layer at the transmitter end in order to indicate that the checksum error has occurred in operations 21-45. The receiving PDCP layer may instruct the lower layer to discard data (e.g., PDCP PDUs) previously generated and transferred to the lower layer, and the lower layer may discard data that has not been transmitted. The receiving PDCP layer may not generate additional PDCP control PDUs until data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied is received from among subsequently received data by using the 1-bit indicator of the user data compression header, and thus unnecessary PDCP control PDU transmission may be prevented. The receiving PDCP layer may discard all data to which the user data compression process is applied, among data whose count value or PDCP sequence number is less than the count value or PDCP sequence number of data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied, by using the 1-bit indicator of the user data compression header, among subsequently received data.

Otherwise, when the user data compression header does not indicate that the transmission UDC buffer has been reset and does not indicate the first data to which user data compression is newly applied (by checking the FR bit) in operations 2j-20 to 2j-30, and when the checksum file of the user data compression header is checked, the checksum checking process is performed, and a checksum error does not occur, the receiving PDCP layer may perform decompression on the data in operation 2 j-35. Otherwise, when the checksum field of the user data compression header is checked, the checksum checking process is performed, and a checksum error occurs in operation 2j-30, the receiving PDCP layer may discard the data and may generate PDCP control PDUs and transmit the PDCP control PDUs to the transmitting PDCP layer at the transmitter end in operation 2j-45 so as to indicate that the checksum error has occurred. The receiving PDCP layer may instruct the lower layer to discard data (e.g., PDCP PDUs) previously generated and transferred to the lower layer, and the lower layer may discard data that has not been transmitted. The receiving PDCP layer may not generate additional PDCP control PDUs until data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied is received from among subsequently received data by using the 1-bit indicator of the user data compression header, and thus unnecessary PDCP control PDU transmission may be prevented. The receiving PDCP layer may discard all data to which the user data compression process is applied, among data whose count value or PDCP sequence number is less than the count value or PDCP sequence number of data indicating that the transmission user data compression buffer has been reset and first data to which user data compression is newly applied, by using the 1-bit indicator of the user data compression header, among subsequently received data.

In operation 2j-10, when the user data compression protocol is configured and the user data is not compressed (when an indicator of the user data compression header may be checked and it may be indicated that the user data is not compressed), the receiving PDCP layer may not perform decompression on the data and may remove the user data compression header in operation 2 j-15. In operation 2j-40, the receiving PDCP layer may transfer data to a higher layer.

Fig. 2K is a block diagram illustrating a structure of a terminal according to an embodiment of the present disclosure.

Referring to fig. 2K, the terminal may include a Radio Frequency (RF) processor 2K-10, a baseband processor 2K-20, a memory 2K-30, and a controller 2K-40.

The RF processors 2k-10 may perform functions of transmitting/receiving signals through a radio channel, such as band conversion or amplification of the signals. That is, the RF processor 2k-10 may up-convert a baseband signal provided from the baseband processor 2k-20 into an RF band signal, and then may transmit the RF band signal through an antenna, and may down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processors 2k-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, digital-to-analog converters (DACs), and analog-to-digital converters (ADCs). Although only one antenna is shown in fig. 2K, the terminal may include a plurality of antennas. Furthermore, the RF processors 2k-10 may include multiple RF chains. In addition, the RF processors 2k-10 may perform beamforming. For beamforming, the RF processors 2k-10 may adjust the phase and magnitude of each signal transmitted/received through multiple antennas or antenna elements. Also, the RF processors 2k-10 may perform MIMO and may receive multiple layers during MIMO operation. The RF processor 2k-10 may perform receive beam scanning by appropriately configuring a plurality of antennas or antenna elements, or may adjust the direction and beam width of the receive beam under the control of the controller 2k-40 so that the receive beam is coordinated with the transmit beam.

The baseband processors 2k-20 may convert between baseband signals and bit streams according to the physical layer specifications of the system. For example, during data transmission, the baseband processors 2k-20 may generate complex symbols by encoding and modulating the transmission bit stream. Further, during data reception, the baseband processor 2k-20 may reconstruct the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 2 k-10. For example, according to an Orthogonal Frequency Division Multiplexing (OFDM) method, during data reception, the baseband processors 2k-20 may generate complex symbols by encoding and modulating a transmission bit stream, may map the complex symbols onto subcarriers, and may configure OFDM symbols by Inverse Fast Fourier Transform (IFFT) and Cyclic Prefix (CP) insertion. Further, during data reception, the baseband processor 2k-20 may segment the baseband signal provided from the RF processor 2k-10 into OFDM symbols, may reconstruct a signal mapped to subcarriers through a Fast Fourier Transform (FFT), and may then reconstruct a received bit stream through demodulation and decoding of the signal.

As described above, the baseband processor 2k-20 and the RF processor 2k-10 may transmit and receive signals. Thus, the baseband processor 2k-20 and the RF processor 2k-10 may be referred to as a transmitter, a receiver, a transceiver, or a communicator. Further, at least one of the baseband processors 2k-20 or the RF processors 2k-10 may include a plurality of communication modules supporting a plurality of different radio access technologies. Further, at least one of the baseband processors 2k-20 or the RF processors 2k-10 may include different communication modules to process signals of different frequency bands. For example, the different radio access technologies may include an LTE network and an NR network. Also, the different frequency bands may include an ultra high frequency (SHF) (e.g., 2.5GHz or 5GHz) band, and a millimeter wave (mmWave) (e.g., 60GHz) band.

The memories 2k-30 may store basic programs, application programs, and data such as configuration information for operating the terminal. The memory 2k-30 may provide stored data upon request of the controller 2 k-40.

The controllers 2k-40 may control the overall operation of the terminal. For example, the controller 2k-40 may transmit/receive signals through the baseband processor 2k-20 and the RF processor 2 k-10. Further, the controller 2k-40 can write data to the memory 2k-40 and read data from the memory 2 k-40. To this end, the controllers 2k-40 may comprise at least one processor. For example, the controllers 2k-40 may include a Communication Processor (CP) for controlling communication and an Application Processor (AP) for controlling a higher layer such as an application program.

Fig. 2L is a block diagram illustrating a structure of a base station (e.g., TRP) according to an embodiment of the present disclosure.

Referring to fig. 2L, the base station may include RF processors 21-10, baseband processors 21-20, backhaul communicators 21-30, memories 21-40, and controllers 21-50.

The RF processor 21-10 may perform a function of transmitting/receiving a signal through a radio channel, such as band conversion or amplification of the signal. That is, the RF processor 21-10 may up-convert a baseband signal provided from the baseband processor 21-20 into an RF band signal, and then may transmit the RF band signal through an antenna, and may down-convert an RF band signal received through the antenna into a baseband signal. For example, the RF processors 21-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, DACs, and ADCs. Although one antenna is shown in fig. 2L, the first connection node may include a plurality of antennas. Also, the RF processors 21-10 may include multiple RF chains. In addition, the RF processor 21-10 may perform beamforming. For beamforming, the RF processors 21-10 may adjust the phase and magnitude of each signal transmitted/received through a plurality of antennas or antenna elements. The RF processors 21-10 may perform downlink MIMO operations by transmitting one or more layers.

The baseband processors 21-20 may convert between baseband signals and bit streams according to the physical layer specification of the first radio access technology. For example, during data transmission, the baseband processors 21-20 may generate complex symbols by encoding and modulating the transmission bit stream. Further, during data reception, the baseband processor 21-20 may reconstruct a reception bit stream by demodulating and decoding the baseband signal provided from the RF processor 21-10. For example, according to the OFDM method, during data transmission, the baseband processors 21 to 20 may generate complex symbols by encoding and modulating a transmission bit stream, may map the complex symbols to subcarriers, and may then configure the OFDM symbols through IFFT and CP insertion. Also, during data reception, the baseband processor 21-20 may segment the baseband signal provided from the RF processor 21-10 into OFDM symbols, may reconstruct a signal mapped to subcarriers through FFT, and may then reconstruct a received bit stream through demodulation and decoding of the signal. As described above, the baseband processor 21-20 and the RF processor 21-10 may transmit and receive signals. Thus, the baseband processor 21-20 and the RF processor 21-10 may be referred to as a transmitter, a receiver, a transceiver, a communicator, or a wireless communicator.

The communicators 21-30 may provide an interface for communicating with other nodes in the network.

The memories 21-40 may store basic programs, application programs, and data such as configuration information for operating the base stations. In particular, the memories 21-40 may store information about bearers assigned to connected terminals, and measurement results reported from connected terminals. Furthermore, the memories 21-40 may store standard information for determining whether to provide or cease multi-connectivity to the terminal. The memories 21-40 may provide stored data upon request by the controllers 21-50.

The controllers 21-50 may control the overall operation of the base station. For example, the controllers 21-50 may transmit/receive signals through the RF processors 21-10 and the baseband processors 21-20 or the backhaul communicators 21-30. In addition, the controllers 21-50 may write data to the storage devices 21-40 and read data from the storage devices 21-40. To this end, the controllers 21-50 may include at least one processor.

While the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to embrace such alterations and modifications as fall within the scope of the appended claims.

Claims

1. A method of performing measurements by a user equipment, UE, the method comprising:

receiving measurement configuration information for measurement in an idle mode or an inactive mode from a base station;

starting a timer based on the measurement configuration information; and

performing measurements in the idle mode or inactive mode while the timer is running;

wherein the measurement configuration information is deleted when the timer expires in the idle mode or inactive mode.

2. The method of claim 1, further comprising:

transmitting a radio resource control, RRC, recovery request message to the base station;

receiving a response message to the RRC recovery request message; and

determining whether to continue performing the measurement based on the response message.

3. The method of claim 2, wherein determining whether to continue performing measurements in the idle mode based on the response message comprises: stopping the running timer and deleting the measurement configuration information when the response message is an RRC setup message or an RRC resume message.

4. The method of claim 2, wherein determining whether to continue performing measurements in the idle mode based on the response message comprises: when the response message is an RRC reject message, continuing to perform measurement in the idle mode or the inactive mode.

5. The method of claim 1, further comprising:

receiving a UE information request message for requesting a measurement result;

transmitting a UE information response message including the measurement result; and

discarding the measurement result.

6. The method of claim 3, further comprising maintaining configuration information for a master cell group (MCGScell) or a Secondary Cell Group (SCG),

wherein the response message includes information indicating whether to reconstruct the configuration information of the Scell or SCG, an

Wherein the configuration information of the Scell or SCG is released or reconstructed based on information indicating whether to reconstruct the configuration information of the Scell or SCG.

7. The method of claim 1, further comprising:

performing a cell reselection procedure; and

stopping the timer and discarding the measurement configuration information when the cell selected based on the cell reselection procedure is not a validity area.

8. The method of claim 1, further comprising:

performing a cell reselection procedure; and

stopping the running timer and discarding the measurement configuration information when the cell selected based on the cell reselection procedure is a cell using another radio access technology, RAT.

9. The method of claim 1, further comprising: maintaining the timer that is running and maintaining the measurement configuration information when the UE transitions from the inactive mode to the idle mode.

10. The method of claim 1, further comprising not stopping the running timer or deleting the measurement configuration information when the UE fails to find a cell to camp on or fails to select a cell.

11. A user equipment, UE, for performing measurements in idle mode or inactive mode, the UE comprising:

a transceiver; and

a processor coupled with the transceiver and configured to receive measurement configuration information for measurements in an idle mode or an inactive mode from a base station, start a timer based on the measurement configuration information, perform measurements in the idle mode or the inactive mode while the timer is running, and remove the measurement configuration information when the timer expires in the idle mode or the inactive mode.

12. The UE of claim 11, wherein the processor is further configured to send a radio resource control, RRC, recovery request message to the base station, receive a response message to the RRC recovery request message, and determine whether to continue to perform measurements based on the response message.

13. The UE of claim 12, wherein the processor is further configured to stop the timer that is running and discard the measurement configuration information when the response message is an RRC setup message or an RRC recovery message.

14. The UE of claim 12, wherein the processor is further configured to continue performing measurements in the idle mode or the inactive mode when the response message is an RRC reject message.

15. The UE of claim 11, wherein the processor is further configured to receive a UE information request message for requesting measurement results, send a UE information response message including the measurement results, and discard the measurement results.