KR20210141127A - Method and apparatus of applying MAC configuration in a wireless communication system - Google Patents

Abstract

The present disclosure relates to a method for a terminal to apply medium access control (MAC) configuration information in a wireless communication system. The method comprises the steps of: receiving an RRC reconfiguration message for handover from a base station; identifying configuration information related to dual active protocol stack (DAPS) handover in the received RRC reset message; generating a target MAC entity based on the identified DAPS handover related configuration information; and performing data transmission/reception with a target cell based on the generated target MAC entity.

Description

Method and apparatus for applying MAC (Medium Access Control) configuration information in a wireless communication system {Method and apparatus of applying MAC configuration in a wireless communication system}

The present disclosure relates to a wireless communication system, and more particularly, to a method of applying MAC (Medium Access Control) configuration information when performing a DAPS (Dual Active Protocol Stack) handover (HO).

Efforts are being made to develop an improved 5G communication system or pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of the 4G communication system. For this reason, the 5G communication system or the pre-5G communication system is called a system after the 4G network (Beyond 4G Network) communication system or after the LTE system (Post LTE). In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to alleviate the path loss of radio waves and increase the propagation distance of radio waves in the very high frequency band, in the 5G communication system, beamforming, massive MIMO, full dimensional MIMO, FD-MIMO ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Technology development is underway. In addition, in the 5G system, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), and advanced access technologies such as FBMC (Filter Bank Multi Carrier), NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

On the other hand, the Internet is evolving from a human-centered connection network where humans create and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers, etc. with IoT technology, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects, and machine to machine communication (Machine to Machine) are required. , M2M), and MTC (Machine Type Communication) are being studied. In the IoT environment, intelligent IT (Internet Technology) services that create new values in human life by collecting and analyzing data generated from connected objects can be provided. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. can be applied to

Accordingly, various attempts are being made to apply the 5G communication system to the IoT network. For example, in technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC), 5G communication technology is implemented by techniques such as beamforming, MIMO, and array antenna. there will be The application of a cloud radio access network (cloud RAN) as the big data processing technology described above is an example of the convergence of 5G technology and IoT technology.

In particular, a method for efficiently applying MAC (Medium Access Control) configuration information is required with the development of a wireless communication system.

An object of the present disclosure is to provide a method of applying MAC (Medium Access Control) protocol related configuration information configured from a base station when performing DAPS handover.

According to an embodiment of the present disclosure, there is provided a method for a terminal to apply medium access control (MAC) configuration information in a wireless communication system, the method comprising: receiving an RRC reconfiguration message for handover from a base station; identifying DAPS (Dual Active Protocol Stack) handover related configuration information in the received RRC reset message; generating a target MAC entity based on the identified DAPS handover related configuration information; and performing data transmission/reception with a target cell based on the generated target MAC entity.

The disclosed embodiment may provide an apparatus and method capable of effectively applying MAC configuration information in a wireless communication system.

1A is a diagram illustrating a structure of an NR system according to an embodiment of the present disclosure.
1B is a diagram illustrating a radio protocol structure in LTE and NR systems according to an embodiment of the present disclosure.
1C is an exemplary diagram of downlink and uplink channel frame structures when communication is performed based on a beam in the NR system according to an embodiment of the present disclosure.
1D is a diagram illustrating a procedure in which a terminal performs contention-based four-step random access to a base station according to an embodiment of the present disclosure.
1E is a diagram for explaining carrier aggregation in a terminal according to an embodiment of the present disclosure.
1F is a diagram illustrating the necessity and role of an uplink timing sync procedure in a system to which an OFDM multiplexing scheme is applied according to an embodiment of the present disclosure.
1G is a diagram schematically illustrating a case in which a plurality of Timing Advance Groups (TAGs) are set according to an embodiment of the present disclosure.
1H is a diagram for explaining a discontinuous reception (DRX) operation of a terminal according to an embodiment of the present disclosure.
1I is a diagram illustrating a process of using a Dual Active Protocol Stack (DAPS) in a process of performing a handover according to an embodiment of the present disclosure.
1J is a diagram illustrating an operation sequence of a terminal in which the terminal applies MAC configuration information during DAPS handover according to an embodiment of the present disclosure.
1K illustrates a block configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure.
11 illustrates a block configuration of a base station in a wireless communication system according to an embodiment of the present disclosure.

Hereinafter, the operating principle of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. And the terms to be described later are terms defined in consideration of functions in the present disclosure, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

A term for identifying an access node used in the following description, a term referring to network entities, a term referring to messages, a term referring to an interface between network objects, and a term referring to various identification information and the like are exemplified for convenience of description. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

Advantages and features of the present disclosure, and a method of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments allow the disclosure of the present disclosure to be complete, and common knowledge in the art to which the present disclosure pertains. It is provided to fully inform those who have the scope of the disclosure, and the present disclosure is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

At this time, it will be understood that each block of the flowchart diagrams and combinations of the flowchart diagrams may be performed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions performed by the processor of the computer or other programmable data processing equipment are not described in the flowchart block(s). It creates a means to perform functions. These computer program instructions may also be stored in a computer-usable or computer-readable memory that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable memory. It is also possible that the instructions stored in the flow chart block(s) produce an article of manufacture containing instruction means for performing the function described in the flowchart block(s). The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for performing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). It should also be noted that in some alternative implementations it is also possible for the functions recited in blocks to occur out of order. For example, two blocks shown one after another may in fact be performed substantially simultaneously, or it is possible that the blocks are sometimes performed in the reverse order according to the corresponding function.

In this case, the term '~ unit' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and '~ unit' performs certain roles do. However, '-part' is not limited to software or hardware. The '~ unit' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Thus, as an example, '~' denotes components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card. Also, in an embodiment, '~ part' may include one or more processors.

In the following description of the present disclosure, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

For convenience of description, the present disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard. However, the present disclosure is not limited by the above terms and names, and may be equally applied to systems conforming to other standards.

Hereinafter, the base station is a subject that performs resource allocation of the terminal, and may be at least one of gNode B, eNode B, Node B, a base station (BS), a radio access unit, a base station controller, or a node on a network. The 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 a communication function. Of course, it is not limited to the above example.

In particular, the present disclosure is applicable to 3GPP NR (5th generation mobile communication standard). In addition, the present disclosure provides intelligent services (eg, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety-related services based on 5G communication technology and IoT-related technology) etc.) can be applied. In the present disclosure, eNB may be used interchangeably with gNB for convenience of description. That is, a base station described as an eNB may represent a gNB. Also, the term terminal may refer to mobile phones, NB-IoT devices, sensors, as well as other wireless communication devices.

A wireless communication system, for example, 3GPP's HSPA (High Speed Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2's High Rate Packet Data (HRPD), UMB (Ultra Mobile Broadband), and IEEE's 802.16e, such as communication standards such as communication standards such as broadband wireless that provides high-speed, high-quality packet data service It is evolving into a communication system.

As a representative example of a broadband wireless communication system, in an LTE system, an Orthogonal Frequency Division Multiplexing (OFDM) scheme is employed in a downlink (DL; DownLink), and Single Carrier Frequency Division Multiple Access (SC-FDMA) in an uplink (UL). ) method is used. Uplink refers to a radio link in which a UE (User Equipment or MS; Mobile Station) transmits data or control signals to a base station (eNode B or BS; Base Station), and downlink refers to a radio link in which the base station transmits data or control to the UE A radio link that transmits signals. The multiple access method as described above divides the data or control information of each user by allocating and operating the time-frequency resources to which data or control information is to be transmitted for each user so that they do not overlap each other, that is, orthogonality is established. .

As a future communication system after LTE, that is, the 5G communication system must be able to freely reflect various requirements such as users and service providers, so services that simultaneously satisfy various requirements must be supported. Services considered for the 5G communication system include Enhanced Mobile BroadBand (eMBB), massive Machine Type Communication (mMTC), and Ultra Reliability Low Latency Communication (URLLC). There is this.

According to some embodiments, the eMBB may aim to provide a data transfer rate that is more improved than the data transfer rate supported by the existing LTE, LTE-A, or LTE-Pro. For example, in the 5G communication system, the eMBB should be able to provide a maximum data rate of 20 Gbps in the downlink and a maximum data rate of 10 Gbps in the uplink from the viewpoint of one base station. In addition, the 5G communication system may have to provide the maximum transmission speed and at the same time provide the increased user perceived data rate of the terminal. In order to satisfy such a requirement, in the 5G communication system, it may be required to improve various transmission/reception technologies, including a more advanced multi-antenna (MIMO) transmission technology. In addition, while transmitting signals using a transmission bandwidth of up to 20 MHz in the 2 GHz band currently used by LTE, the 5G communication system uses a frequency bandwidth wider than 20 MHz in the frequency band of 3 to 6 GHz or 6 GHz or more Data transfer speed can be satisfied.

At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in the 5G communication system. In order to efficiently provide the Internet of Things, mMTC may require large-scale terminal access support, improved terminal coverage, improved battery life, and reduced terminal cost within a cell. Since the Internet of Things is attached to various sensors and various devices to provide communication functions, it must be able to support a large number of terminals (eg, 1,000,000 terminals/km2) within a cell. In addition, since the terminal supporting mMTC is highly likely to be located in a shaded area that the cell does not cover, such as the basement of a building, due to the nature of the service, wider coverage may be required compared to other services provided by the 5G communication system. A terminal supporting mMTC should be composed of a low-cost terminal, and since it is difficult to frequently exchange the battery of the terminal, a very long battery life time such as 10 to 15 years may be required.

Finally, in the case of URLLC, as a cellular-based wireless communication service used for a specific purpose (mission-critical), remote control for a robot or a machine, industrial automation, It may be used for a service used in an unmanned aerial vehicle, remote health care, emergency alert, and the like. Therefore, the communication provided by URLLC may have to provide very low latency (ultra-low latency) and very high reliability (ultra-reliability). For example, a service supporting URLLC must satisfy an air interface latency of less than 0.5 milliseconds, and at the same time may have a requirement of a packet error rate of ^{10 -5 or less.} Therefore, for a service supporting URLLC, the 5G system must provide a smaller Transmit Time Interval (TTI) than other services, and at the same time, it is a design that must allocate wide resources in a frequency band to secure the reliability of the communication link. items may be required.

The three services considered in the above-described 5G communication system, ie, eMBB, URLLC, and mMTC, may be multiplexed and transmitted in one system. In this case, different transmission/reception techniques and transmission/reception parameters may be used between services to satisfy different requirements of each service. However, the aforementioned mMTC, URLLC, and eMBB are only examples of different service types, and the service types to which the present disclosure is applied are not limited to the above-described examples.

For convenience of description, the present disclosure uses terms and names defined in LTE and NR standards, which are the latest standards defined by the 3rd Generation Partnership Project (3GPP) organization among communication standards that currently exist. However, the present disclosure is not limited by the above terms and names, and may be equally applied to systems conforming to other standards. In particular, the present disclosure is applicable to 3GPP NR (5th generation mobile communication standard). In addition, the embodiment of the present disclosure may be applied to other communication systems having a similar technical background or channel type. In addition, the embodiments of the present disclosure may be applied to other communication systems through some modifications within a range that does not significantly depart from the scope of the present disclosure as judged by a person having skilled technical knowledge.

Hereinafter, when using 3GPP 5G NR (New Radio) technology, DAPS (Dual Active Protocol Stack) handover (HO) is set to communicate simultaneously with the source base station and the destination base station while performing handover, MAC protocol A method for applying related setting information is proposed.

Through the present disclosure, information set from the base station during DAPS handover is applied to the target MAC entity, so that it does not interfere with data communication in the source MAC entity, thereby reducing delay.

1A is a diagram illustrating a structure of an NR system according to an embodiment of the present disclosure. Referring to FIG. 1A , a wireless communication system includes a plurality of base stations (1a-05, 1a-10, 1a-15, 1a-20) and an Access and Mobility Management Function (AMF) (1a-20) and a User Plane (UPF). Function) (1a-30). User equipment (hereinafter referred to as UE or terminal) 1a-35 may access an external network through base stations 1a-05, 1a-10, 1a-15, 1a-20 and UPF 1a-30. . Of course, the wireless communication system is not limited to the example of FIG. 1A , and may include more or fewer configurations than those illustrated in FIG. 1A .

The base stations 1a-05, 1a-10, 1a-15, and 1a-20 are access nodes of the cellular network and may provide wireless access to terminals accessing the network. That is, the base stations 1a-05, 1a-10, 1a-15, and 1a-20 collect and schedule status information such as the buffer status of the terminals, the available transmission power status, and the channel status in order to service the traffic of users. It is possible to support the connection between the terminals and a core network (CN, Core network; in particular, CN of NR is referred to as 5GC). On the other hand, the communication system including the NR system can be configured to process traffic by dividing it into a user plane (UP) related to the transmission of actual user data and a control plane (CP) such as connection management. In the figure, gNBs (1a-05, 1a-20) use UP and CP related technologies defined in NR technology, and ng-eNBs (1a-10, 1a-15) are connected to 5GC, but UP defined in LTE technology and CP-related techniques may be used.

The AMF (or SMF) 1a-25 is a device in charge of various control functions as well as a mobility management function for the terminal and is connected to a plurality of base stations, and the UPF 1a-30 is a kind of gateway device that provides data transmission. can be

1B is a diagram illustrating a radio protocol structure in LTE and NR systems according to an embodiment of the present disclosure.

Referring to Figure 1b, the radio protocol of the LTE system is PDCP (Packet Data Convergence Protocol) (1b-05, 1b-40), RLC (Radio Link Control) (1b-10, 1b-35) in the terminal and ENB, respectively, MAC (Medium Access Control) (1b-15, 1b-30) may include a layer (or device).

PDCP (Packet Data Convergence Protocol) (1b-05, 1b-40) may be in charge of operations such as IP header compression/restore, and radio link control (hereinafter referred to as RLC) (1b-10, 1b) -35) may reconfigure a PDCP PDU (Packet Data Unit) to an appropriate size.

The MACs 1b-15 and 1b-30 may be connected to several RLC layer devices configured in one terminal, and may perform operations of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs.

The physical layer (1b-20, 1b-25) channel-codes and modulates upper layer data, creates OFDM symbols and transmits them over a wireless channel, or demodulates and channel-decodes OFDM symbols received through a wireless channel. An operation of transferring to a higher layer may be performed. In addition, for additional error correction in the physical layer, HARQ (Hybrid ARQ) may be used, and the receiving end may transmit whether a packet transmitted from the transmitting end is received with 1 bit. This is called HARQ ACK/NACK information.

Downlink HARQ ACK/NACK information for uplink data transmission is transmitted through a PHICH (Physical Hybrid-ARQ Indicator Channel) physical channel in the case of LTE, and PDCCH, which is a channel through which downlink/uplink resource allocation, etc. are transmitted in the case of NR It may be provided based on the scheduling information of the corresponding terminal in (Physical Dedicated Control CHannel). That is, in the NR, the base station or the terminal can determine whether retransmission of uplink data is necessary or whether new transmission is required through the PDCCH. This is because asynchronous HARQ is applied in NR. Uplink HARQ ACK/NACK information for downlink data transmission may be transmitted through a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH) physical channel. PUCCH is generally transmitted in the uplink of a PCell (Primary Cell) to be described later. However, if the base station supports the terminal, it may be additionally transmitted to the corresponding terminal in a secondary cell (SCell) to be described later. This is referred to as the PUCCH SCell. call it

Although not shown in this figure, a radio resource control (RRC) layer may exist above the PDCP layer of the terminal and the base station, respectively, and the RRC layer may send and receive access and measurement related configuration control messages for radio resource control. For example, the UE may be instructed to measure by using the message of the RRC layer, and the UE may report the measurement result to the base station using the message of the RRC layer.

Meanwhile, the physical layer may be configured using one or a plurality of frequencies/carriers, and a technique for simultaneously setting and using a plurality of frequencies is called carrier aggregation (hereinafter, referred to as CA). CA technology refers to the use of only one carrier for communication between the UE (or User Equipment, UE) and the base station (E-UTRAN NodeB, eNB). The amount of transmission can be dramatically increased by the number of Meanwhile, in LTE, a cell in a base station using a primary carrier is called a primary cell or PCell (Primary Cell), and a cell in a base station using a subcarrier is called a secondary cell or SCell (Secondary Cell).

1C is an exemplary diagram of downlink and uplink channel frame structures when communication is performed based on a beam in an NR system according to an embodiment of the present disclosure.

In FIG. 1C , the base station 1c-01 may transmit a signal in the form of beams 1c-11, 1c-13, 1c-15, and 1c-17 in order to transmit a wider coverage or a stronger signal. Accordingly, the terminal 1c-03 in the cell may need to transmit/receive data using a specific beam (beam #1 (1c-13) in FIG. 1C) transmitted by the base station.

On the other hand, depending on whether the terminal is connected to the base station, the state of the terminal may be divided into a dormant mode (or idle mode) (RRC_IDLE) and a connected mode (RRC_CONNECTED) state. Accordingly, the base station may not know the location of the terminal in the dormant mode.

If the terminal in the dormant mode wants to transition to the connected mode state, the terminal receives the synchronization blocks (Synchronization Signal Block, SSB) (1c-21, 1c-23, 1c-25, 1c-27) transmitted by the base station. can do. SSB is an SSB signal transmitted periodically according to the period set by the base station, and each SSB is a Primary Synchronization Signal (PSS) (1c-41), a Secondary Synchronization Signal (SSS) (1c- 43), and may include a Physical Broadcast CHannel (PBCH).

In FIG. 1C, a scenario in which an SSB is transmitted for each beam is assumed. For example, SSB#0 (1c-21) is transmitted using beam #0 (1c-11), and SSB#1 (1c-23) is transmitted using beam #1 (1c-13). In the case of SSB#2 (1c-25), beam #2 (1c-15) is used for transmission, and for SSB#3 (1c-27), beam #3 (1c-17) is used for transmission. was assumed. In addition, although it is assumed in FIG. 1C that the terminal in the dormant mode is located in beam #1, even when the terminal in the connected mode performs random access, the terminal selects the received SSB at the time of performing the random access.

Referring to FIG. 1C , the UE may receive SSB #1 transmitted through beam #1. Upon receiving SSB #1, the UE acquires a Physical Cell Identifier (PCI) of the base station through PSS and SSS, and receives the PBCH identifier of the currently received SSB (ie, #1) and the current SSB It is possible to determine not only where the received position is within the 10 ms frame, but also which SFN it is in the System Frame Number (SFN) having a period of 10.24 seconds. In addition, the MIB (Master Information Block) may be included in the PBCH, and the MIB may include information on where the SIB1 (System Information Block Type 1) broadcasting more detailed cell configuration information can be received. have. Upon receiving SIB1, the terminal can know the total number of SSBs transmitted by the base station, and can perform random access to transition to the connected mode state (more precisely, a preamble that is a physical signal specially designed to match uplink synchronization) It is possible to determine the location of the PRACH occasion (Physical Random Access CHannel) (assuming a scenario allocated every 1 ms in FIG. 1c: from (1c-30) to (1c-39)). In addition, the UE can know which PRACH occasion among PRACH occasions is mapped to which SSB index based on the information of SIB1. For example, in FIG. 1C , a scenario in which 1 ms is allocated is assumed, and a scenario in which 1/2 SSB is allocated per PRACH Occasion (ie, 2 PRACH Occasions per SSB) is assumed. Accordingly, a scenario in which two PRACH occasions are allocated for each SSB is shown from the start of the PRACH Occasion that starts according to the SFN value. That is, PRACH Occasion (1c-30) and PRACH Occasion (1c-31) may be allocated for SSB#0, and PRACH Occasion (1c-32) and PRACH Occasion (1c-33) may be allocated for SSB#1. . After setting for all SSBs, PRACH Occasion is allocated again for the first SSB (PRACH Occasion (1c-38) and PRACH Occasion (1c-39)).

Accordingly, the UE recognizes the location of the PRACH occasion (1c-32, 1c-33) for SSB#1, and accordingly, the most at the current time among the PRACH Occasions (1c-32, 1c-33) corresponding to SSB#1. A random access preamble can be transmitted as a fast PRACH Occasion (eg, PRACH Occasion (1c-32)). Since the base station received the preamble from the PRACH Occasion (1c-32), it can be seen that the terminal selected SSB#1 to transmit the preamble, and then, when performing random access, data is transmitted through the beam corresponding to SSB#1. can transmit and receive.

Meanwhile, when the connected terminal moves from the current (source) base station to the destination (target) base station for reasons such as handover, the terminal performs random access in the target base station, and selects the SSB to transmit the random access. can be done In addition, during handover, a handover command is transmitted to the terminal to move from the source base station to the target base station. In this case, the handover command message is dedicated to the terminal for each SSB of the target base station so that it can be used when performing random access in the target base station. (dedicated) A random access preamble identifier may be allocated. In this case, the base station may not allocate a dedicated random access preamble identifier to all beams (according to the current location of the terminal, etc.), and accordingly, a dedicated random access preamble may not be allocated to some SSBs (eg, Dedicated random access preamble is assigned to Beam #2 and #3 only).

If a dedicated random access preamble is not allocated to an SSB selected by the UE for preamble transmission, random access may be performed by randomly selecting a contention-based random access preamble. For example, in this figure, after the UE first performs random access by being located in Beam #1 and fails, a scenario in which the UE is located in Beam #3 and transmits the dedicated preamble when transmitting the random access preamble again may be possible. random access. That is, when preamble retransmission occurs even within one random access procedure, the contention-based random access procedure and the non-contention-based random access procedure are mixed depending on whether a dedicated random access preamble is allocated to the selected SSB for each preamble transmission. can be

1D is a diagram illustrating a procedure in which a terminal performs contention-based four-step random access to a base station according to an embodiment of the present disclosure.

1D is a diagram illustrating a contention-based four-step random access procedure performed by a UE in various cases requiring initial access, reconnection, handover, and other random access to a base station.

In step 1d-11, the terminal 1d-01 may select a PRACH according to FIG. 1c for access to the base station 1d-03 and transmit a random access preamble to the corresponding PRACH. According to an embodiment of the present disclosure, a case in which one or more UEs simultaneously transmit a random access preamble with a PRACH resource may occur. The PRACH resource may span one subframe, or only some symbols within one subframe may be used. The information on the PRACH resource may be included in the system information broadcast by the base station 1d-03, and accordingly, it can be known with which time frequency resource the preamble should be transmitted. In addition, the random access preamble is a specific sequence specially designed so that it can be received even if it is transmitted before being completely synchronized with the base station 1d-03, and there may be a plurality of preamble identifiers (index) according to the standard. If there are a plurality of preamble identifiers, the preamble transmitted by the terminal 1d-01 may be randomly selected by the terminal, or may be a specific preamble designated by the base station 1d-03.

In step 1d-21, when the base station 1d-03 receives the preamble, the base station 1d-03 sends a random access response (hereinafter referred to as RAR) message to the terminal 1d-01. can be transmitted The RAR message includes identifier information of the preamble used in step 1d-11, uplink transmission timing correction information, uplink resource allocation information to be used in a later step (that is, step 1d-31), and temporary terminal identifier information. can The identifier information of the preamble may be transmitted to indicate which preamble the RAR message is a response message to, for example, when a plurality of terminals transmit different preambles to attempt random access in step 1d-11. The uplink resource allocation information may be detailed information of the resource to be used by the UE in step 1d-31, the physical location and size of the resource, a decoding and coding scheme (MCS) used for transmission, and power adjustment during transmission information may be included. Temporary terminal identifier information may be a value transmitted to be used for the terminal, which has transmitted the preamble, since the terminal does not have the identifier allocated by the base station for communication with the base station when the terminal makes initial access.

The RAR message should be transmitted within a predetermined period starting from a predetermined time after sending the preamble, and a predetermined period starting after a predetermined time after sending the preamble is referred to as a 'RAR window'. The RAR window may be a time interval starting from a point in time when a predetermined time has elapsed from the transmission of the preamble. That is, the RAR window may start from a point in time when a predetermined time has passed since the transmission of the first preamble. The predetermined time may have a subframe unit (1 ms) or a smaller value. In addition, the length of the RAR window may be a predetermined value set by the base station for each PRACH resource or for one or more PRACH resource sets in a system information message broadcast by the base station.

Meanwhile, when the RAR message is transmitted, the base station schedules the RAR message through the PDCCH, and the corresponding scheduling information may be scrambled using a Random Access-Radio Network Temporary Identifier (RA-RNTI). The RA-RNTI is mapped to the PRACH resource used to transmit the message in step 1d-11, and the terminal that has transmitted the preamble to the specific PRACH resource attempts to receive the PDCCH based on the RA-RNTI and whether there is a corresponding RAR message. can be judged If the RAR message is a response to the preamble transmitted by the UE in step 1d-11 as shown in this exemplary diagram, the RA-RNTI used for this RAR message scheduling information includes information on the corresponding (1d-11) transmission. do. For this purpose, RA-RNTI may be calculated by the following equation. Of course, it is not limited to the following examples:

RA-RNTI= 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 × ul_carrier_id

In this case, s_id is an index corresponding to the first OFDM symbol in which the preamble transmission started in step 1d-11, and may have a value of 0 ≤ s_id < 14 (ie, the maximum number of OFDM symbols in one slot). In addition, t_id is an index corresponding to the first slot in which the preamble transmission transmitted in step 1d-11 is started, and may have a value of 0 ≤ t_id < 80 (ie, the maximum number of slots in one system frame (10 ms)). In addition, f_id indicates to which PRACH resource the preamble transmitted in step 1d-11 is transmitted on a frequency, which may have a value of 0 ≤ f_id < 8 (ie, the maximum number of PRACHs on a frequency within the same time). In addition, ul_carrier_id determines whether the preamble is transmitted in the basic uplink (Normal Uplink, NUL) when two carriers are used in uplink for one cell (in this case 0), and whether the preamble is transmitted in the supplementary uplink (SUL). It can be a parameter to distinguish whether it has been transmitted (in this case, 1)

In step 1d-31, the UE receiving the RAR message may transmit another message to the resource allocated to the RAR message according to the various purposes described above. The message transmitted in step 1d-31 of FIG. 1d is the third transmitted message and is also called Msg3 (that is, the preamble of step 1d-11 is called Msg1, and the RAR of step 1d-21 is called Msg2). For example, an RRCConnectionRequest message that is a message of the RRC layer in case of initial connection, an RRCConnectionReestablishmentRequest message in case of reconnection, and an RRCConnectionReconfigurationComplete message in case of handover may be included, and the example is not limited thereto. Alternatively, a buffer status report (BSR) message for requesting a resource may be transmitted as Msg3.

Thereafter, in case of initial transmission (ie, when Msg3 does not include base station identifier information previously assigned to the terminal, etc.), in step 1d-41, the terminal may receive a contention resolution message from the base station, The cancellation message includes the contents transmitted by the terminal in Msg3 as it is, so that even if there are a plurality of terminals that have selected the same preamble in step 1d-11, the response to which terminal can be notified.

On the other hand, at the end of the uplink allocated for Msg3 transmission through RAR or PDCCH (eg, the first OFDM symbol after the corresponding uplink), the contention resolution timer (ra-ContentionResolutionTimer) is started or restarted. Accordingly, the terminal attempts to receive Msg4 from the base station until the timer expires. If Msg4 is not received until the timer expires, the terminal determines that contention resolution has failed, and may retransmit the preamble.

1E is a diagram for describing a carrier aggregation technique in a terminal according to an embodiment of the present disclosure.

Referring to FIG. 1E, in one base station, multiple carriers are generally transmitted and received over several frequency bands. For example, when a carrier 1e-15 having a center frequency of f1 and a carrier having a center frequency of f3 (1e-10) are transmitted from the base station 1e-05, in the prior art, one terminal uses one of the two carriers. data was transmitted and received using a carrier of However, a terminal having a carrier aggregation capability can transmit and receive data from multiple carriers at the same time. The base station 1e-05 may increase the transmission speed of the terminal 1e-30 by allocating more carriers depending on the situation to the terminal 1e-30 having the carrier aggregation capability.

In a traditional sense, when one forward carrier and one reverse carrier transmitted and received from one base station constitute one cell, carrier aggregation may be understood as a terminal transmitting and receiving data through several cells at the same time. will be. Through this, the maximum transmission rate is increased in proportion to the number of aggregated carriers.

Hereinafter, in describing the embodiments of the present disclosure, the control provided by the cell corresponding to the center frequency and frequency band characterizing the carrier means that the terminal receives data through an arbitrary forward carrier or transmits data through an arbitrary reverse carrier. It may have the same meaning as transmitting/receiving data using a channel and a data channel. In addition, an embodiment of the present disclosure will be described below assuming an LTE system for convenience of description, but the present disclosure may be applied to various wireless communication systems supporting carrier aggregation.

Even with or without carrier aggregation, reverse transmission power must be maintained at an appropriate level because reverse (ie, from the terminal to the base station) transmission causes interference in the reverse direction of other cells. To this end, the terminal may calculate a reverse transmission output using a predetermined function in performing reverse transmission, and perform reverse transmission with the calculated reverse transmission output. For example, the UE inputs scheduling information such as the amount of allocated transmission resources and the applied MCS (Modulation Coding Scheme) level and input values for estimating the channel condition such as the path loss value into a predetermined function, and the required reverse transmission output value , and applying the calculated required reverse transmission output value, reverse transmission may be performed. The reverse transmission output value applicable to the terminal is limited by the maximum transmission value of the terminal, and if the calculated requested transmission output value exceeds the maximum transmission value of the terminal, the terminal applies the maximum transmission value to perform reverse transmission. . In this case, since a sufficient reverse transmission power cannot be applied, reverse transmission quality may deteriorate. It may be desirable for the base station to perform scheduling so that the requested transmission power does not exceed the maximum transmission power. However, since some parameters such as path loss cannot be grasped by the base station, the terminal transmits a power headroom report (PHR, Power Headroom Report) when necessary to determine its available transmission output (PH, Power Headroom) state by the base station. can be reported to

Factors affecting the available transmission power include 1) the amount of allocated transmission resources, 2) MCS to be applied to reverse transmission, 3) path loss of the associated forward carrier, and 4) the accumulated value of output adjustment commands. Since the path loss (hereinafter referred to as PL) or the accumulated output adjustment command value may be different for each uplink carrier, it may be preferable to set whether to transmit the PHR for each uplink carrier when a plurality of uplink carriers are aggregated in one terminal. However, for efficient PHR transmission, one uplink carrier may report all power headrooms (PHs) for a plurality of uplink carriers. Depending on the operation strategy, the PH for the carrier in which the actual PUSCH (Physical Uplink Shared CHannel) transmission has not occurred may be required. Accordingly, in this case, a method of reporting all PHs for a plurality of uplink carriers in one uplink carrier may be more efficient. For this, it may be necessary to extend the existing PHR. A plurality of PHs to be included in one PHR may be configured according to a predetermined order.

The PHR is usually triggered when the path loss of the connected forward carrier changes to a predetermined reference value or more, the prohibit PHR timer expires, or a predetermined period elapses after the PHR is generated. Even if the PHR is triggered, the UE does not immediately transmit the PHR, but waits until a time when reverse transmission is possible, for example, a time when a reverse transmission resource is allocated. This is because PHR is not information that needs to be processed very quickly.

1F is a diagram illustrating the necessity and role of an uplink timing sync procedure in a system to which an OFDM multiplexing scheme is applied according to an embodiment of the present disclosure.

Referring to FIG. 1F , UE1 (hereinafter referred to as terminal 1) indicates a terminal located close to an NB (base station), and UE2 (hereinafter referred to as terminal 2) indicates a terminal far away from the NB. The first propagation delay time (hereinafter, T_pro1) represents a propagation delay time in radio transmission to the terminal 1, and the second propagation delay time (hereinafter, T_pro2) in the radio transmission to the terminal 2 represents the propagation delay time of As shown in Fig. 1f, since the terminal 1 is located closer to the NB than the terminal 2, it can have a relatively small propagation delay time. For example, in FIG. 1F , T_pro1 may be 0.333us, and T_pro2 may be 3.33us.

When terminal 1 and terminal 2 are powered on in one cell of the NB of FIG. 1f or when terminal 1 and terminal 2 are in idle (idle) mode, the uplink transmission of terminal 1 is performed by the base station There may be a problem that the time point at which the terminal 2 arrives and the time point at which the uplink transmission of the terminal 2 arrives at the base station do not coincide with each other. That is, uplink synchronization may not match.

As an example, (1f-01) shows the timing for OFDM symbol uplink transmission at the uplink transmission time of the terminal 1. Also, (1f-03) shows the timing for OFDM symbol uplink transmission at the uplink transmission time of the terminal 2. Considering the propagation delay time of the uplink transmission of the terminal 1 and the terminal 2, the timing at the base stations (Node B, NB) receiving the uplink OFDM symbol and the timing at which the transmission signals of the terminals 1 and 2 arrive are may be shown as (1f-05), (1f-07), and (1f-09), respectively. That is, the uplink symbol of the terminal 1 transmitted at the timing of (1f-01) has a propagation delay time and can be received at the NB with the timing of (1f-07). In addition, the uplink symbol of terminal 2 transmitted at the timing of (1f-03) has a propagation delay time and can be received at the NB with the timing of (1f-09). Referring to FIG. 1f, since the timing at which the transmission of each terminal arrives at the base station, that is, (1f-07) and (1f-09), is before the uplink uplink synchronization of the terminal 1 and the terminal 2 is adjusted, The NB receives and decodes the uplink OFDM symbol at a start time (1f-05), at a time point at which it receives the OFDM symbol from Terminal 1 (1f-07), and at a time point at which it receives the OFDM symbol from Terminal 2 (1f-09). ) is different from each other.

Accordingly, since the uplink symbols transmitted from the terminal 1 and the terminal 2 do not have orthogonality, they may act as interference with each other. Accordingly, the NB receives the interference due to the uplink symbols transmitted from the terminal 1 and the terminal 2 and the arrival time of the uplink signal of the terminal 1 (1f-07) and the base station reference time (1f- 05), due to the uplink symbol reception timing at the uplink signal arrival time (1f-09) of terminal 2 that is different from 05), the uplink symbol transmitted from terminal 1 and terminal 2 cannot be successfully decoded. can

The uplink timing sync procedure is a process in which the uplink symbol reception timings of Terminal 1, Terminal 2, and NB are identically matched. Upon completion of the uplink timing synchronization procedure, (1f-11), (1f-13), and (1f- 15), the start timing of receiving and decoding the NB and the uplink OFDM symbol, the timing of receiving the uplink OFDM symbol from the terminal 1, and the timing of receiving the uplink OFDM symbol from the terminal 2 can be aligned. More specifically, by aligning the uplink symbol reception timing with an error within the length of the CP (Cyclic-Prefix), the base station can enable the decoding of the uplink symbol.

In the uplink timing sync procedure, the NB may transmit timing advance (Timing Advance, hereinafter referred to as TA) information to the terminals to provide information on how much timing should be adjusted. More specifically, on the basis of the predetermined downlink 1f-21, the NB may provide information on how much earlier to transmit compared to the corresponding downlink to the terminals.

At this time, the TA information is transmitted by the NB through the Timing Advance Command MAC Control Element (hereinafter referred to as TAC MAC CE) or a response message to the random access preamble transmitted by the terminal for initial access. (Random Access Response, hereinafter referred to as RAR) may also be transmitted. In more detail, in the case of RAR, TA information may correspond to 11 bits (T _A = 0, 1, 2, ..., 1282), and thus N _TA = T _A * 16 may be calculated. In addition, the TAC MAC CE may have a TA value of 6 bits, and a relative value that is changed according to the _{existing N TA} value (N _{TA,old ) may be calculated.} That is, _{the relative value changed according to the existing N TA} value (N _TA,old ) may follow the following formula: N _TA,new = N _TA,old + (T _A -31)*16. Accordingly, the uplink transmission time may _{correspond to (N TA} * N _{TA_offset} ) * Ts before the downlink reference. That is, the uplink _{may be transmitted before the downlink (N TA} * N _{TA_offset} ) * Ts (1f-23). The _{value of N TA_offset} may be 0 for the FDD system and 624 for the TDD system. Also, Ts may have a value of 1/ (2048 * subcarrier spacing). Accordingly, the terminal can adjust the uplink transmission time using the TA information.

Upon receiving the TA information, the UE may start a time alignment timer (timeAlignmentTimer, hereinafter referred to as TAT). The TAT may be a timer indicating whether the TA is valid. That is, it is determined that the TA is valid in the section in which the TAT operates, but it cannot be guaranteed that the TA is valid after the operation of the TAT expires.

The UE may restart the TAT when additional TA information is subsequently received, etc., and when the TAT expires after a certain period of time, it is determined that the TA information received from the base station is no longer valid and uplink with the corresponding NB. Communication can be interrupted.

If the timings are matched in the above manner, the uplink symbols transmitted from Terminal 1 and Terminal 2 can maintain orthogonality, and the NB is the uplink symbol transmitted from Terminal 1 of (1f-01) and (1f-03). It is possible to successfully decode the uplink symbol transmitted from terminal 2 of

1G is a diagram schematically illustrating a case in which a plurality of Timing Advance Groups (TAGs) are set according to an embodiment of the present disclosure. Referring to FIG. 1G , when carrier aggregation is used, a case in which device positions between a main carrier and a sub-carrier are different is illustrated.

Referring to Figure 1g, the remote radio equipment (Remote Radio Head, RRH) using the F2 frequency band (1g-07) around the macro base station (1g-01) using the F1 frequency band (1g-05) (1g) -03) may be distributed. If the terminal uses the macro base station and the remote wireless equipment at the same time or is located near the remote wireless equipment, when the terminal sends a signal to the remote wireless equipment, the signal may reach the appropriate time even if it shoots a little later because the distance is close. However, when the terminal shoots a signal to the macro base station, since the distance is long, the signal must be fired earlier to arrive at an appropriate time. That is, in one terminal, when carrier aggregation is used, a plurality of uplink timings need to be aligned. Accordingly, there is a need for a TAT operation method according to a plurality of uplink timings.

To this end, in the embodiment of the present disclosure, the base station groups and manages carriers having the same or similar uplink timing. This is called a Timing Advance Group (hereinafter referred to as a TAG).

That is, for example, when one PCell (or first cell) and three SCells (or second cell) A, B, and C exist, when PCell and SCell A have similar uplink timing, It can be managed by grouping this into one group 1 and SCell B and SCell C as group 2. That is, when the base station commands to control uplink timing by transmitting TA information through TAC MAC CE or RAR for group 1, the terminal applies information included in the TAC MAC CE to both the corresponding PCell and SCell A. The uplink timing may be adjusted accordingly. In addition, along with the TA information reception, the terminal may operate the TAT for group 1. The TAT is a timer indicating whether TA information is valid, and only when the TAT is operating for the group 1, uplink data can be transmitted to carriers belonging to the group 1 (ie, PCell and Scell A). If the TAT expires after a certain period of time, it is determined that the TA information is no longer valid, and the UE cannot transmit data on the corresponding carrier until it receives the TA information from the base station.

On the other hand, as in Group 1, if the TAT for the group including the PCell among the carriers in the group, that is, the PTAG (Primary TAG), it is called P-TAG TAT, and as in Group 2, the TAT for the group that does not include the PCell. In this case, STAG (Secondary TAG) may be referred to as TAT.

1H is a diagram for explaining a discontinuous reception (hereinafter referred to as DRX) operation of a terminal according to an embodiment of the present disclosure.

DRX means that according to the configuration of the base station to minimize power consumption of the terminal, instead of monitoring all physical downlink control channels (hereinafter referred to as PDCCH) to obtain scheduling information, some This is a technology that monitors only the PDCCH. A basic DRX operation may have a DRX cycle (1h-00), and the PDCCH may be monitored only for an onDuration (1h-05) time. In the connected mode, two values of long DRX and short DRX may be set for the DRX cycle. In a general case, a long DRX cycle is applied, and if necessary, the base station may additionally set a short DRX cycle. When both the long DRX cycle and the short DRX cycle are set, the UE starts the short DRX timer and repeats from the short DRX cycle. The DRX cycle can be changed to the DRX cycle. If scheduling information for a new packet is received by the PDCCH during the on-duration (1h-05) time (1h-10), the UE may start the DRX inactivity timer (1h-15). The UE maintains an active state during the DRX inactivity timer. That is, the UE may continue monitoring the PDCCH. Also, the HARQ RTT timer (1h-20) may be started. The HARQ RTT timer may be applied to prevent the UE from unnecessarily monitoring the PDCCH during the HARQ Round Trip Time (RTT) time, and during the timer operation time, the UE may not need to perform PDCCH monitoring. However, while the DRX inactivity timer and the HARQ RTT timer are operating simultaneously, the UE may continue monitoring the PDCCH based on the DRX inactivity timer. When the HARQ RTT timer expires, the DRX retransmission timer (1h-25) may be started. While the DRX retransmission timer is operating, the UE must perform PDCCH monitoring. In general, during the DRX retransmission timer operation time, scheduling information for HARQ retransmission may be received (1h-30). Upon receiving the scheduling information, the UE may immediately stop the DRX retransmission timer and start the HARQ RTT timer again. The above operation may continue until the packet is successfully received (1h-35). In addition, if the base station no longer has data to send to the corresponding terminal while the on-duration or DRX inactivity timer is operating, the base station may transmit a DRX Command MAC CE message. Upon receiving the DRX Command MAC CE message, the UE can stop both the on-duration timer and the DRX inactivity timer, and when short DRX is set, the short DRX cycle is used first. can be used

1I is a diagram illustrating a process of using a Dual Active Protocol Stack (DAPS) in a process of performing a handover according to an embodiment of the present disclosure.

When performing a general handover, the UE may stop transmitting/receiving data with the source cell when receiving handover configuration information, and after the handover process is successfully performed, the UE may start transmitting/receiving data with the target cell. Therefore, an interruption time may occur during a time period in which data transmission/reception cannot be performed from after stopping data transmission/reception with the source cell until starting transmission/reception with the target cell. If the UE has a dual active protocol stack, data transmission/reception with the source cell may be maintained during a time period in which data transmission/reception cannot be performed. In the present disclosure, a handover in consideration of the capability of a terminal having a dual active protocol stack may be referred to as a Dual Active Protocol Stack (DAPS) handover. When the DAPS handover is configured, the UE may simultaneously receive downlink data from the source cell and the target cell only for data belonging to the data bearer for which the DAPS operation is configured. A bearer is a logical data path, and the base station can configure a plurality of different bearers according to data types, and when there are a plurality of data bearers, the base station can configure DAPS for each bearer. However, simultaneous uplink data transmission to the source cell and the target cell may be possible only when a predetermined condition is satisfied due to a lack of terminal transmission power or signal interference. In order to minimize terminal complexity, only one link is possible for uplink data transmission during DAPS handover, and the uplink for data transmission may be switched from a source cell to a target cell at a specific time point.

The active state and terminal operation of the dual protocol stack corresponding to the source cell and the target cell may be different for each major specific time point.

Before handover is performed (1i-05), the UE may use only the protocol stack corresponding to the source cell.

When the DAPS handover configuration information is provided to the terminal and RACH is performed to the target cell (1i-10), the terminal receives the DAPS handover configuration information through the RRCReconfiguration message, and a protocol stack corresponding to the target cell can be configured. have. For example, in the case of the MAC layer, in addition to the source MAC entity used in the source base station, a target MAC entity performing random access in the target base station may be additionally generated. However, the UE can still use only the protocol stack corresponding to the source cell. Even if the protocol stack corresponding to the target cell is in an inactive state, it may be irrelevant.

During the RACH execution period (1i-15), when the RACH operation is started, at least the PHY layer and the MAC layer are activated in the protocol stack corresponding to the target cell, so that the RACH operation can be performed. In this case, the UE may still maintain data transmission/reception with the source cell.

When the time (1i-20) for the terminal to transmit the HO success completion message to the target cell comes, the terminal activates at least some functions of the PHY layer, the MAC layer, the RLC layer, and the PDCP layer in the protocol stack corresponding to the target cell, Signaling It should be able to handle the HO success completion message, which is a radio bearer. The UE may transmit uplink data to the source cell at least before transmitting the HO success completion message to the target cell.

After the UE receives the RAR from the target cell (1i-25), all of the dual active protocol stacks may be activated. The UE may maintain data transmission/reception with the source cell until a specific time arrives after RAR reception. Also, a time point at which the terminal can maintain downlink data reception with the source cell and a time point at which uplink data transmission can be maintained may be different. The UE may transmit uplink data to the source cell before transmitting the HO successful completion message to the target cell, but downlink data reception is possible even after transmitting the HO successful completion message to the target cell.

After the UE releases the source cell (1i-30), the protocol stack corresponding to the source cell may also be released. After releasing the source cell, the UE can use only the protocol stack corresponding to the target cell.

1J is a diagram illustrating an operation sequence of a terminal in which the terminal applies MAC configuration information during DAPS handover according to an embodiment of the present disclosure.

Referring to FIG. 1J, it is assumed that the terminal accesses the base station and is in an RRC connection state. In the RRC connection state, the terminal may perform data transmission/reception with the base station.

The terminal may receive a handover command to move to another base station from the base station (1j-03). The handover command may mean a case in which the reconfigurationWithSync field is included in the RRCReconfiguration message of the RRC layer. The reconfigurationWithSync field may include identifier information of a terminal to be used by the target base station and length information of a timer T304 used to detect handover failure. Optionally, the terminal may be allocated a dedicated resource (the aforementioned dedicated random access preamble) that can be used during the random access procedure when accessing the target base station for the handover procedure. In addition, the base station may receive the above-described MAC layer related configuration information through the mac-CellGroupConfig field in the RRCReconfiguration message. In more detail, the base station may receive one or more configuration information among a TAG-related configuration (set by the tag-Config field in the field) and DRX-related configuration (set by the drx-Config field in the field) in the mac-CellGroupConfig field.

Meanwhile, in order to reduce delay during handover, the base station may instruct the UE to handover using the above-described DAPS (hereinafter referred to as DAPS HO). DAPS HO can be executed only when there is a bearer in which the daps-Config field is set to true among the data bearers configured to the UE in the RRCReconfiguration message.

If DAPS HO related configuration information is not included in the RRCReconfiguration message (1j-05), the UE may stop the DRX operation (1j-15). In addition, the DRX operation by drx-Config included in the RRCReconfiguration message may be started from the first time point. The first time point may be a time point at which a system frame number (SFN) of a target PCell performing handover is acquired. In addition, the terminal may stop all currently configured TAG-related TAT(s) at the second time point, and change the TAG-related configuration information to tag-Config included in the RRCReconfiguration message at the third time point. The second time point and the third time point are arbitrary time points before receiving the RRCReconfiguration message and starting random access in the target PCell, respectively, and the second time point may take precedence over the third time point.

However, if DAPS HO-related configuration information is included in the RRCReconfiguration message (1j-05), the UE may additionally create a MAC enitity for the target eNB in the UE to perform handover using the above-described DAPS. There is (1j-11). In this case, as various configuration information of the additionally created target MAC entity, the same configuration information as that used in the previous source MAC entity may be used. For example, if there is information used by the previous source MAC entity in relation to the above-described TAG and DRX related configuration information, the terminal may create a target MAC entity having the same configuration information as the information used in the previous source MAC entity. have. Even after the target MAC entity is created, the UE may maintain the DRX operation in the source MAC entity. Also, the UE may apply the DRX operation by drx-Config included in the mac-CellGroupConfig field in the RRCReconfiguration message to the target MAC entity from the first time point (1j-13). That is, the DRX operation by drx-Config may not be applied to the source MAC entity, but may be an operation applied only to the target MAC entity. The first time point may be a time point at which the SFN of the target PCell is acquired. Also, even after the UE creates the target MAC entity, the UE may maintain TAG-related settings in the source MAC entity, and may maintain operation without terminating the TATs of the source MAC entities. Accordingly, the terminal may perform uplink data transmission with the source base station. Also, the UE may apply the tag-Config included in the mac-CellGroupConfig field in the RRCReconfiguration message to the target MAC entity at the second time point (1j-13). That is, the TAG related configuration information by tag-Config may not be applied to the source MAC entity, but may be information applied only to the target MAC entity. In more detail, the TAG-related configuration information by tag-Config may include a tag-ToReleaseList field for deleting previous TAG information and a tag-ToAddModList field for addition and modification in tag-Config. If the terminal receives the RRCReconfiguration message for DAPS HO from the base station, the terminal may delete TAG information included in the tag-ToReleaseList field from the TAG configuration of the generated target MAC entity. That is, the terminal corresponds to the identifier of the corresponding TAG included in the tag-ToReleaseList field (tag-Id: for example, 0 in the case of PTAG and may have numbers such as 1, 2, 3, etc. in the case of STAG). Information can be deleted. In addition, the terminal may receive the RRCReconfiguration message for DAPS HO from the base station, and obtain the tag-ToAddModList field from the TAG setting of the generated target MAC entity. If the identifier of the corresponding TAG included in the tag-ToAddModList field does not exist in the created target MAC entity, the corresponding TAG may be newly added to the target MAC entity. Alternatively, if the identifier of the corresponding TAG included in the tag-ToAddModList field exists in the generated target MAC entity, the terminal may reconfigure the configuration information of the existing target MAC entity to the received TAG configuration information. The second time point may be any time point before receiving the RRC message and initiating random access in the target PCell.

Accordingly, the terminal does not cut off data communication with the source base station, but at the same time updates the MAC-related configuration information to be used by the target base station and completes the handover procedure, thereby reducing the handover delay.

1K illustrates a block configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure.

Referring to FIG. 1K , the terminal may include a radio frequency (RF) processing unit (1k-10), a baseband processing unit (1k-20), a storage unit (1k-30), and a control unit (1k-40). have. Of course, it is not limited to the above example, and the terminal may include fewer or more configurations than the configuration shown in FIG. 1K .

The RF processing unit 1k-10 performs a function for transmitting and receiving a signal through a wireless channel, such as band conversion and amplification of the signal. That is, the RF processing unit 1k-10 up-converts the baseband signal provided from the baseband processing unit 1k-20 into an RF band signal, transmits it through the antenna, and converts the RF band signal received through the antenna to the baseband. downconverted to a signal. For example, the RF processing unit 1k-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC), and the like. have. Although only one antenna is shown in FIG. 1K , the terminal may include a plurality of antennas. Also, the RF processing unit 1k-10 may include a plurality of RF chains. Furthermore, the RF processing unit 1k-10 may perform beamforming. For beamforming, the RF processing unit 1k-10 may adjust the phase and magnitude of each of signals transmitted and received through a plurality of antennas or antenna elements.

The baseband processing unit 1k-20 performs a function of converting between a baseband signal and a bit stream according to the physical layer standard of the system. For example, when transmitting data, the baseband processing unit 1k-20 generates complex symbols by encoding and modulating the transmitted bit stream. Also, upon data reception, the baseband processing unit 1k-20 restores the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 1k-10. For example, in the case of orthogonal frequency division multiplexing (OFDM), when transmitting data, the baseband processing unit 1k-20 encodes and modulates a transmitted bit stream to generate complex symbols, and maps the complex symbols to subcarriers. After that, OFDM symbols are constructed through inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. In addition, upon data reception, the baseband processing unit 1k-20 divides the baseband signal provided from the RF processing unit 1k-10 into OFDM symbol units, and is mapped to subcarriers through a fast Fourier transform (FFT) operation. After restoring the signals, the received bit stream is restored through demodulation and decoding.

The baseband processing unit 1k-20 and the RF processing unit 1k-10 transmit and receive signals as described above. Accordingly, the baseband processing unit 1k-20 and the RF processing unit 1k-10 may be referred to as a transmitter, a receiver, a transceiver, or a communication unit. Furthermore, at least one of the baseband processing unit 1k-20 and the RF processing unit 1k-10 may include a plurality of communication modules to support a plurality of different wireless access technologies. In addition, at least one of the baseband processing unit 1k-20 and the RF processing unit 1k-10 may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include a wireless LAN (eg, IEEE 802.11), a cellular network (eg, LTE), and the like. In addition, the different frequency bands may include a super high frequency (SHF) (eg, 2.5 GHz, 5 GHz) band and a millimeter wave (eg, 60 GHz) band. The terminal may transmit/receive a signal to and from the base station using the baseband processing unit 1k-20 and the RF processing unit 1k-10, and the signal may include control information and data.

The storage unit 1k-30 stores data such as a basic program, an application program, and setting information for the operation of the terminal. In particular, the storage unit 1k-30 may store information related to a wireless LAN node performing wireless communication using a wireless LAN access technology. In addition, the storage unit 1k-30 provides stored data according to the request of the control unit 1k-40. The storage unit 1k-30 may be configured of a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. Also, the storage unit 1k-30 may include a plurality of memories. According to an embodiment of the present disclosure, the storage unit 1k-30 may store a program for a method for the terminal according to the present disclosure to apply medium access control (MAC) configuration information.

The controller 1k-40 controls overall operations of the terminal. For example, the control unit 1k-40 transmits and receives signals through the baseband processing unit 1k-20 and the RF processing unit 1k-10. In addition, the control unit 1k-40 writes and reads data in the storage unit 1k-40. To this end, the controller 1k-40 may include at least one processor. For example, the controller 1k-40 may include a communication processor (CP) that controls for communication and an application processor (AP) that controls an upper layer such as an application program. In addition, at least one component in the terminal may be implemented as one chip. Also, according to an embodiment of the present disclosure, the control unit 1k-40 includes a multi-connection processing unit 1k-42 that performs processing for operating in a multi-connection mode. For example, the controller 1k-40 may control the terminal to perform the procedure illustrated in the operation of the terminal illustrated in FIG. 1J .

The controller 1k-40 according to an embodiment of the present disclosure may control the MAC protocol configuration information of the RRCReconfiguration message received during DAPS HO to be applied only to the target MAC entity in the above-described manner.

11 illustrates a block configuration of a base station in a wireless communication system according to an embodiment of the present disclosure.

Referring to FIG. 11 , the base station may include an RF processing unit 11-10, a baseband processing unit 11-20, a communication unit 11-30, a storage unit 11-40, and a control unit 11-50. have. Of course, it is not limited to the above example, and the base station may include fewer or more configurations than the configuration shown in FIG. 11 .

The RF processing unit 11-10 may perform a function for transmitting and receiving a signal through a wireless channel, such as band conversion and amplification of the signal. The RF processing unit 11-10 up-converts the baseband signal provided from the baseband processing unit 11-20 into an RF band signal, transmits it through an antenna, and converts the RF band signal received through the antenna into a baseband signal. can be down-converted. For example, the RF processing unit 11-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like. Although only one antenna is shown in FIG. 11, the RF processing unit 11-10 may include a plurality of antennas. Also, the RF processing unit 11-10 may include a plurality of RF chains. Also, the RF processing unit 11-10 may perform beamforming. For beamforming, the RF processing unit 11-10 may adjust the phase and magnitude of each of signals transmitted and received through a plurality of antennas or antenna elements. The RF processing unit 11-10 may perform a downlink MIMO operation by transmitting one or more layers.

The baseband processing unit 11-20 may perform a function of converting a baseband signal and a bit stream according to a physical layer standard of a predetermined radio access technology. For example, when transmitting data, the baseband processing unit 11-20 may generate complex symbols by encoding and modulating the transmitted bit stream. Also, upon data reception, the baseband processing unit 11-20 may restore the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 11-10. For example, in the OFDM scheme, when data is transmitted, the baseband processing unit 11-20 generates complex symbols by encoding and modulating the transmission bit stream, maps the complex symbols to subcarriers, and performs IFFT operation and OFDM symbols can be configured through CP insertion. Also, upon data reception, the baseband processing unit 11-20 divides the baseband signal provided from the RF processing unit 11-10 into OFDM symbol units, and restores signals mapped to subcarriers through FFT operation. , it is possible to restore the received bit stream through demodulation and decoding. The baseband processing unit 11-20 and the RF processing unit 11-10 may transmit and receive signals as described above. Accordingly, the baseband processing unit 11-20 and the RF processing unit 11-10 may be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit. The base station may transmit/receive a signal to/from the terminal using the baseband processing unit 11-20 and the RF processing unit 11-10, and the signal may include control information and data.

The communication unit 11-30 provides an interface for performing communication with other nodes in the network. That is, the communication unit 11-30 converts a bit string transmitted from the main base station to another node, for example, an auxiliary base station, a core network, etc. into a physical signal, and converts a physical signal received from the other node into a bit string do. The communication unit 11-30 may be a backhaul communication unit.

The storage unit 11-40 stores data such as a basic program, an application program, and setting information for the operation of the base station. The storage 11-40 may store information on a bearer allocated to an accessed terminal, a measurement result reported from the accessed terminal, and the like. In addition, the storage unit 11-40 may store information serving as a criterion for determining whether to provide or stop multiple connections to the terminal. In addition, the storage unit 11-40 provides the stored data according to the request of the control unit 11-50. The storage unit 11-40 may be configured of a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. Also, the storage unit 11-40 may be composed of a plurality of memories. According to some embodiments, according to some embodiments, the storage unit 11-40 may store a program for a method for the base station to perform beam failure detection and recovery for the SpCell according to the present disclosure.

The controller 11-50 controls overall operations of the base station. For example, the control unit 1i-50 transmits and receives signals through the baseband processing unit 11-20 and the RF processing unit 11-10 or through the communication unit 11-30. In addition, the control unit 11-50 writes and reads data in the storage unit 11-40. To this end, the controller 11-50 may include at least one processor. According to an embodiment of the present disclosure, the control unit 11-50 includes a multi-connection processing unit 11-52 that performs processing for operating in a multi-connection mode.

In addition, at least one configuration of the base station may be implemented with one chip. In addition, each configuration of the base station may be operable to perform the above-described embodiments of the present disclosure.

Methods according to the embodiments described in the claims or specifications of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors in an electronic device (device). One or more programs include instructions for causing an electronic device to execute methods according to embodiments described in a claim or specification of the present disclosure.

Such programs (software modules, software) include random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable ROM (EEPROM: Electrically Erasable Programmable Read Only Memory), magnetic disc storage device, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or any other form of It may be stored in an optical storage device or a magnetic cassette. Alternatively, it may be stored in a memory composed of a combination of some or all thereof. In addition, a plurality of each configuration memory may be included.

In addition, the program is transmitted through a communication network consisting of a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. It may be stored on an attachable storage device that can be accessed. Such a storage device may be connected to a device implementing an embodiment of the present disclosure through an external port. In addition, a separate storage device on the communication network may be connected to the device implementing the embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed in the singular or plural according to the specific embodiments presented. However, the singular or plural expression is appropriately selected for the situation presented for convenience of description, and the present disclosure is not limited to the singular or plural component, and even if the component is expressed in plural, it is composed of a singular or singular. Even an expressed component may be composed of a plurality of components.

Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments and should be defined by the claims described below as well as the claims and equivalents. That is, it will be apparent to those of ordinary skill in the art to which the present disclosure pertains that other modifications may be implemented based on the technical spirit of the present disclosure. In addition, each of the above embodiments may be operated in combination with each other as needed. For example, a base station and a terminal may be operated by combining parts of the methods proposed in the present disclosure. In addition, although the above embodiments have been presented based on 5G and NR systems, other modifications based on the technical idea of the embodiments may be implemented in other systems such as LTE, LTE-A, and LTE-A-Pro systems.

Claims (1)

In a method for a terminal to apply MAC (Medium Access Control) configuration information in a wireless communication system,
Receiving an RRC reconfiguration message for handover from a base station;
identifying DAPS (Dual Active Protocol Stack) handover related configuration information in the received RRC reset message;
generating a target MAC entity based on the identified DAPS handover related configuration information; and
Based on the generated target MAC entity, comprising the step of performing data transmission and reception with a target cell.

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