CN110249660B

CN110249660B - Method and apparatus for transmitting and receiving data in mobile communication system

Info

Publication number: CN110249660B
Application number: CN201880009675.9A
Authority: CN
Inventors: 文廷敃; H.范德维尔德; 朴承勋; 郑柄薰
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2017-02-02
Filing date: 2018-02-02
Publication date: 2023-07-21
Anticipated expiration: 2038-02-02
Also published as: KR102420813B1; EP3563606A1; KR20180090178A; KR20180090177A; EP3563606A4; KR20190105035A; CN110249660A

Abstract

The present disclosure relates to communication methods and systems for fusing fifth generation (5G) communication systems supporting higher data rates than fourth generation (4G) systems with internet of things (IoT) technologies. The present disclosure may be applied to smart services based on 5G communication technology and IoT-related technology, such as smart homes, smart buildings, smart cities, smart cars, networked cars, healthcare, digital education, smart retail, security and security services. The present disclosure also relates to cell reselection operations. The method of a terminal in a wireless communication system may include: the method includes receiving first scheduling information for a first frequency band from a base station, switching a bandwidth to the first frequency band according to the first scheduling information, starting a timer for the first frequency band, and switching the bandwidth to a second frequency band when the timer expires.

Description

Method and apparatus for transmitting and receiving data in mobile communication system

Technical Field

The present disclosure relates to mobile communication systems. More particularly, the present disclosure relates to a cell reselection method for a terminal.

Furthermore, the present disclosure relates to cell measurement and mobility management operations using signals transmitted by beamforming in a beamforming-based system.

Furthermore, the present disclosure relates to a method for transmitting a reference signal for a terminal in a radio resource control (radio resource control, RRC) connected state.

Furthermore, the present disclosure relates to a method for switching a bandwidth of a terminal in a mobile communication system.

Background

In order to meet the increased demand for wireless data services since the deployment of fourth generation (4G) communication systems, efforts have been made to develop improved fifth generation (5G) or pre-5G communication systems. Thus, a 5G or pre-5G communication system is also referred to as a "super 4G network" or a "Long Term Evolution (LTE) after-system". A 5G communication system is considered to be implemented in a millimeter wave (mmWave) band of higher frequencies (e.g., 60GHz band) in order to achieve higher data rates. In order to reduce propagation loss of radio waves and increase transmission distance, beamforming, massive Multiple Input Multiple Output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, massive antenna techniques are discussed in 5G communication systems. Further, in the 5G communication system, development for system network improvement is being conducted based on advanced small cells, cloud Radio Access Networks (RANs), ultra dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, cooperative multipoint (CoMP), receiving-end interference cancellation, and the like. In 5G systems, hybrid Frequency Shift Keys (FSK) and Quadrature Amplitude Modulation (QAM) (FQAM) and Sliding Window Superposition Coding (SWSC) have been developed as Advanced Code Modulation (ACM), and Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA), and Sparse Code Multiple Access (SCMA) as advanced access techniques.

As human-centric connected networks for human generation and consumption of information, the internet is now evolving into the internet of things (Internet of things, ioT) in which distributed entities such as things exchange and process information without human intervention. A web (Internet of everything, ioE) has emerged as a everything network that combines IoT technology and big data processing technology through a connection with a cloud server. As technology elements such as "sensing technology", "wired/wireless communication and network infrastructure", "service interface technology", and "security technology" have been demanded by IoT implementations, sensor networks, machine-to-machine (M2M) communications, machine Type Communications (MTC), etc. have been recently studied. Such IoT environments may provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated between connected things. Through the convergence and integration of existing Information Technology (IT) with various industrial applications, ioT is applicable in a number of fields including smart homes, smart buildings, smart cities, smart cars or networked cars, smart grids, healthcare, smart appliances, and advanced medical services.

In keeping with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, techniques such as sensor networks, MTC, and M2M communications may be implemented by beamforming, MIMO, and array antennas. Application of the cloud RAN as the big data processing technology described above may also be considered as an example of a fusion between 5G technology and IoT technology.

The above information is provided merely as background information to aid in the understanding of the present disclosure. No determination is made nor is it asserted whether any of the above may be applicable to the prior art relating to the present disclosure.

Disclosure of Invention

Technical problem

The present invention has been made to solve at least the problems and/or disadvantages and to provide at least the advantages described below.

Technical proposal

Aspects of the present disclosure are directed to solving at least the problems and/or disadvantages described above and to providing at least the advantages described below. Accordingly, it is an aspect of the present disclosure to provide a method for preferentially reselecting a specific cell by a terminal, thereby enabling fast data transmission and reception of the terminal and preventing an increase in signaling overhead occurring in a data transmission/reception preparation process.

Another aspect of the present disclosure is to provide a system, method, and apparatus for performing cell measurement and mobility management operations using signals transmitted through beamforming in a beamforming-based system including one or more Base Stations (BSs) and one or more terminals.

Another aspect of the present disclosure is to provide a method and apparatus for transmitting a reference signal for a terminal in a Radio Resource Control (RRC) connected state.

Another aspect of the present invention is to provide a process of receiving a base station signal within a limited frequency band by considering power consumption of a terminal in a single carrier, and also to provide a method of flexibly and dynamically utilizing an entire system frequency band by a base station and a terminal. Furthermore, the present disclosure provides a method and procedure for a terminal to save power in such a flexible bandwidth system.

According to one aspect of the present disclosure, a method of a terminal in a wireless communication system is provided. The method comprises the following steps: the method includes receiving first scheduling information for a first frequency band from a base station, switching a bandwidth to the first frequency band according to the first scheduling information, starting a timer for the first frequency band, and switching the bandwidth to a second frequency band when the timer expires.

According to another aspect of the present disclosure, a method of a base station in a wireless communication system is provided. The method comprises the following steps: the method includes transmitting first scheduling information for a first frequency band to a terminal, switching a bandwidth to the first frequency band according to the first scheduling information, starting a timer for the first frequency band, and switching the bandwidth to a second frequency band when the timer expires.

According to another aspect of the present disclosure, a terminal in a wireless communication system is provided. The terminal comprises: the wireless communication device includes a transceiver and a controller configured to receive first scheduling information for a first frequency band from a base station, switch a bandwidth to the first frequency band according to the first scheduling information, start a timer for the first frequency band, and switch the bandwidth to a second frequency band when the timer expires.

According to another aspect of the present disclosure, a base station in a wireless communication system is provided. The base station comprises: the wireless communication device includes a transceiver and a controller configured to transmit first scheduling information for a first frequency band to a terminal, switch a bandwidth to the first frequency band according to the first scheduling information, start a timer for the first frequency band, and switch the bandwidth to a second frequency band when the timer expires.

Advantageous effects of the invention

According to another aspect of the present disclosure, a terminal may reselect a specific cell capable of fast data transmission/reception, thereby preventing an increase in signaling overhead that may occur in preparation for data transmission/reception.

According to another aspect of the present disclosure, each base station may transmit two or more reference signals generated by different signal generation rules by using two or more beams having different beam areas, coverage areas, transmission periods, and the like.

According to another aspect of the present disclosure, a base station may determine a beam to be used for data transmission by transmitting a reference signal for a terminal in an RRC connected state, and perform data transmission/reception using the determined beam.

According to another aspect of the present disclosure, a base station may control a plurality of terminals using frequency bands of various sizes to uniformly use resources in an operation frequency band of a system. In addition, the base station allows the terminal to perform scheduling, modulation and coding schemes (modulation and coding scheme, MCS), channel state indication (channel state indication, CSI) reporting, measurement, etc. within a configured partial frequency band, thereby minimizing degradation of scheduling and handover performance throughout the frequency band. Also, if a connection problem occurs in such a partial band, the terminal can recover it within a short delay.

Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.

Drawings

The foregoing and other aspects, features, and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a diagram illustrating a case where a User Equipment (UE) moves in a Radio Access Network (RAN) area after a transition from a connected mode to an inactive mode according to an embodiment of the present disclosure;

fig. 2 is a diagram illustrating operation of an inactive mode UE receiving Downlink (DL) data from a gnode B (gNB) with a valid cell radio network temporary identifier (cell radio network temporary identifier, C-RNTI) according to an embodiment of the present disclosure;

fig. 3 is a diagram illustrating operation of an inactive mode UE receiving DL data from all gnbs in a RAN area through a regional cell radio network temporary identifier (area cell radio network temporary identifier, a-RNTI) according to an embodiment of the present disclosure;

fig. 4 is a diagram illustrating an operation of an inactive mode UE that receives paging signals from all gnbs in a RAN area through an a-RNTI, performs a 2-step random access channel (random access channel, RACH), and receives DL data from a gNB that receives a RACH preamble through the a-RNTI, according to an embodiment of the present invention;

fig. 5 is a diagram illustrating an operation of an inactive mode UE that receives paging signals from all gnbs in a RAN area through an a-RNTI, performs a 4-step RACH, and receives DL data from a gNB that receives a RACH preamble through the a-RNTI, according to an embodiment of the present disclosure;

Fig. 6 is a diagram illustrating a difference between a gNB with a valid C-RNTI and a gNB without a valid C-RNTI in a cell reselection of an inactive mode UE in accordance with an embodiment of the present disclosure;

fig. 7 is a diagram illustrating a cell reselection operation in the case where an inactive mode UE moves from a gNB with a valid C-RNTI to a gNB without a valid C-RNTI, in accordance with an embodiment of the present disclosure;

fig. 8 is a diagram illustrating a cell reselection operation in the case where an inactive mode UE moves from a gNB with no valid C-RNTI to a gNB with a valid C-RNTI, in accordance with an embodiment of the present disclosure;

fig. 9 is a diagram illustrating a cell reselection operation in the case where an inactive mode UE moves from a gNB with no valid C-RNTI to another gNB with no valid C-RNTI, in accordance with an embodiment of the present disclosure;

fig. 10 is a diagram illustrating a cell reselection operation in the case where an inactive mode UE moves from a gNB with a valid C-RNTI to another gNB with a valid C-RNTI, in accordance with an embodiment of the present disclosure;

fig. 11 is a diagram illustrating transmission of different types of reference signals having the same period through different frequency bands according to an embodiment of the present disclosure;

fig. 12 is a diagram illustrating transmission of different types of reference signals having the same period through the same frequency band according to an embodiment of the present disclosure;

Fig. 13 is a diagram illustrating transmission of different types of reference signals having different periods through the same frequency band according to an embodiment of the present disclosure;

fig. 14 is a diagram illustrating a method of a terminal calculating measurement values of cells transmitting different reference signals according to an embodiment of the present disclosure;

fig. 15 is a diagram illustrating a method for classifying measured signals into the same type of reference signals and calculating a cell representative value by using measured values according to an embodiment of the present disclosure;

fig. 16 is a diagram illustrating a method of calculating a cell representative value by using all measured reference signals according to an embodiment of the present disclosure;

fig. 17 is a diagram illustrating a method for calculating a cell representative value according to an embodiment of the present disclosure;

fig. 18 and 19 illustrate examples of signals transmitted by a base station to a terminal and used to calculate cell measurements according to embodiments of the present disclosure;

fig. 20 is a diagram illustrating an example of a signal including weights transmitted by a base station to a terminal according to an embodiment of the present disclosure;

fig. 21 is a diagram illustrating a method in which a terminal calculates a cell representative value of each Reference Signal (RS) from different RSs through a separate process according to an embodiment of the present disclosure;

fig. 22 is a diagram illustrating a method of controlling a change in mobility by using different types of reference signals according to an embodiment of the present disclosure;

Fig. 23 illustrates a method of calculating representative values of respective RSs by separate procedures for different types of RSs and then determining one cell representative value by using the above-described representative values according to an embodiment of the present disclosure;

fig. 24 illustrates a method for multiplying each beam measurement signal by the same weight for the same type of RS and then determining a cell representative value according to an embodiment of the present disclosure;

fig. 25 illustrates a method for selecting a specific number of beam measurement signals for different types of RSs, multiplying a representative value of each RS by a weight, thereby deriving a cell representative value, according to an embodiment of the present disclosure;

fig. 26 illustrates a method for selecting a specific number of beam measurement signals for different types of RSs, calculating a representative value for each RS type by multiplying each selected beam measurement signal by a weight, and deriving a cell representative value by multiplying the representative value for each RS type by the weight, according to an embodiment of the present disclosure;

fig. 27 illustrates another method for selecting a different number of beam measurement signals for different types of RSs and then deriving a cell representative value by multiplying the selected signals by different weights, according to an embodiment of the present disclosure;

Fig. 28 is a diagram illustrating a method for deriving a cell representative value by multiplying all beam measurement signals by different weights for different types of RSs according to an embodiment of the present disclosure;

fig. 29 is a diagram illustrating a method of controlling mobility change by using different types of reference signals according to an embodiment of the present disclosure;

fig. 30 is a diagram illustrating a terminal according to an embodiment of the present disclosure;

fig. 31 is a diagram illustrating a base station according to an embodiment of the present disclosure;

fig. 32 is a flowchart illustrating an initial access operation according to an embodiment of the present disclosure;

fig. 33 is a flowchart illustrating a handover operation according to an embodiment of the present disclosure;

FIG. 34 is a flowchart illustrating operation according to an embodiment of the present disclosure;

fig. 35 to 41 are flowcharts illustrating various methods for determining beams to be used for data transmission and reception in a handover procedure according to embodiments of the present disclosure;

fig. 42 is a flowchart illustrating a random access operation according to an embodiment of the present disclosure;

fig. 43-47 are flowcharts illustrating various methods for determining beams to be used for data transmission and reception in a random access procedure according to various embodiments of the present disclosure;

fig. 48 is a diagram illustrating a Long Term Evolution (LTE) scalable Bandwidth (BW) system according to an embodiment of the present disclosure;

FIG. 49 is a diagram illustrating features of a fifth generation (5G) New Radio (NR) flexible BW system in accordance with an embodiment of the disclosure;

fig. 50 is a diagram illustrating various band partitioning schemes in a 5G NR flexible BW system according to an embodiment of the present disclosure;

fig. 51 is a diagram illustrating a self-band/cross-band scheduling operation according to an embodiment of the present disclosure;

fig. 52 to 54 are diagrams illustrating an example of BW expansion and reduction operations by a physical layer control signal according to various embodiments of the present disclosure;

fig. 55 to 58 are diagrams illustrating an example of BW expansion and reduction operations by a physical layer and a Radio Resource Control (RRC) control signal according to various embodiments of the present disclosure;

fig. 59 and 60 are diagrams illustrating examples of connected mode discontinuous reception (connected mode discontinuous reception, C-DRX) operations for adaptive BW according to various embodiments of the present disclosure;

fig. 61 is a diagram illustrating an example of discontinuous reception (discontinuous reception, DRX) settings for wideband and narrowband in accordance with an embodiment of the present disclosure;

fig. 62 and 63 are diagrams illustrating examples of DRX settings and priority rules for wideband and narrowband according to various embodiments of the disclosure;

Fig. 64 is a flowchart illustrating an operation of a terminal according to an embodiment of the present disclosure;

fig. 65 illustrates DRX operation for transmission time interval (transmit time interval, TTI) change according to an embodiment of the present disclosure;

fig. 66 is a diagram illustrating an example of determining TTI values based on control channel monitoring periodicity and transmission duration according to an embodiment of the disclosure;

fig. 67 to 71 are diagrams illustrating timer-based band switching operations according to various embodiments of the present disclosure;

fig. 72 is a diagram showing a configuration of a terminal according to an embodiment of the present disclosure; and

fig. 73 is a diagram showing a configuration of a base station according to an embodiment of the present disclosure.

Throughout the drawings, it should be noted that the same reference numerals are used to depict the same or similar elements, features and structures.

Detailed Description

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the disclosure defined by the claims and their equivalents. It includes various specific details to aid understanding, but these are to be considered exemplary only. Accordingly, one of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to written meanings, but are used only by the inventors to enable a clear and consistent understanding of the disclosure. Accordingly, it will be apparent to those skilled in the art that the following descriptions of the various embodiments of the present disclosure are provided for illustration only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

It should be understood that the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "component surface" includes reference to one or more such surfaces.

Advantages and features of the present disclosure and the manner in which they are achieved will become apparent from the embodiments described in detail below with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. The present disclosure is limited only by the scope of the claims. Like reference numerals refer to like elements throughout the present disclosure.

< first embodiment >

In the New Radio (NR) currently being discussed in the third generation partnership project (3 GPP), the introduction of an inactive mode is decided in addition to a connection mode and an idle mode defined in Long Term Evolution (LTE). The characteristics and requirements of the inactive mode are as follows.

Signaling and resource usage in the Radio Access Network (RAN) and the Core Network (CN) should be minimized.

The time required for data transmission in inactive mode should be minimized. Here, the data transmission may be performed while a User Equipment (UE) maintains an inactive mode or in a connected mode.

Paging through RAN should be supported, existing paging through CN of LTE.

Defining a RAN-based notification area (hereinafter, RAN area). In the RAN area, the UE moves without a location update. A g-node B (gNB) in the RAN area maintains an Access Stratum (AS) context for the UE.

According to the above requirements, the inactive-mode UE should be able to perform an operation for fast data transmission/reception. One of the operations is cell reselection. Basically, as in the requirements above, the inactive mode UE moves within the RAN area without a location update. However, if the inactive mode UE performs cell reselection through the same operation as the idle mode UE in the existing LTE, this may be unsuitable in view of fast data transmission/reception.

Fig. 1 is a diagram illustrating a case where a UE moves in a RAN area after a transition to an inactive mode according to an embodiment of the present disclosure.

Referring to fig. 1, an environment of the present disclosure is shown. In such an environment or scenario as shown in fig. 1, the RAN notification area is formed of a plurality of gnbs, which are classified as a gNB 110 with a cell radio network temporary identifier (C-RNTI) valid for an inactive mode UE and a gNB 120 without a valid C-RNTI. The inactive mode UE is free to move within the RAN announcement region.

In the case of fig. 1, the UE that has been connected to the gNB 110 with the C-RNTI transitions from connected mode to inactive mode and then moves freely in the RAN area.

In fig. 1, the gNB 110, which finally provides services to the UE, maintains the C-RNTI used by the UE according to the definition of the inactive mode that maintains the AS context of the UE. Thus, if the inactive-mode UE sends data to the gNB 110 and receives data from the gNB 110, the C-RNTI does not have to be reconfigured.

On the other hand, even though the gNB 120 belongs to the RAN area of the UE, the gNB 120 does not have the C-RNTI of the inactive mode UE. Thus, when an inactive mode UE communicates with the gNB 120 instead of the gNB 110 with the C-RNTI of the UE, the gNB 120 needs a procedure to assign the C-RNTI to the UE when moving in the RAN area. This may increase delays in data transmission and reception for inactive mode UEs.

In 3GPP, the introduction of a separate Radio Network Temporary Identifier (RNTI) for data transmission/reception of an inactive mode UE is being discussed. In this disclosure, this is referred to as an area RNTI (a-RNTI). The a-RNTI is an identifier designed to allow all UEs in the RAN area to be uniquely allocated. Because the RAN area includes multiple cells, the a-RNTI has a larger overhead than a C-RNTI designed to allow UEs in a cell to be uniquely allocated.

Fig. 2 to 5 below illustrate operations of an inactive-mode UE that receives DL data from a gNB in a RAN area according to an embodiment of the present disclosure.

Fig. 2 is a diagram illustrating an operation of an inactive mode UE receiving Downlink (DL) data from a gNB with a valid C-RNTI, according to an embodiment of the present disclosure.

Referring to fig. 2, since the gNB has the C-RNTI, the gNB may transmit data by using the C-RNTI in operation S210.

Fig. 3 to 5 are diagrams illustrating an operation of an inactive-mode UE receiving DL data from a gNB that does not maintain a C-RNTI in a RAN area according to an embodiment of the present disclosure.

Referring to fig. 3, fig. 3 shows that all the gnbs belonging to the RAN area transmit DL data to the inactive-mode UE by using the a-RNTI in operation S310. Because the UE is in most cases actually adjacent to one gNB, transmitting DL data by using a unique a-RNTI for all the gnbs in the RAN area is an inefficient use of resources.

Fig. 4 and 5 are diagrams illustrating an operation of an inactive-mode UE that identifies and receives DL data from a neighboring gNB by performing a 2-step or 4-step Random Access Channel (RACH) according to an embodiment of the present disclosure.

First, in operation S410 or S510, all the gnbs belonging to the RAN area perform paging by using the a-RNTI of the UE. Then, the UE responding to the page performs 2-step or 4-step RACH and notifies the gNB via RACH message 1 (S420) or RACH message 3 (S520): the UE corresponds to an a-RNTI included in the paging signal. The gNB that received the message recognizes that the inactive mode UE is located nearby and transmits DL data. This operation incurs overhead because all the gnbs in the RAN area send paging signals. In addition, other overhead occurs in the process that the UE must perform 2-step or 4-step RACH operation.

Referring to fig. 2 to 5, when the gNB has a valid C-RNTI, data transmission/reception of the inactive-mode UE has minimum delay and requires minimum signaling of the UE and the gNB. Thus, it is advantageous for the inactive mode UE to stay around the gNB with valid C-RNTI as long as possible. This aspect should be reflected in the cell reselection operation of the inactive mode UE. The present disclosure proposes a cell selection operation that allows an inactive mode UE to stay around a gNB with a valid C-RNTI as long as possible.

First, a cell reselection operation of the UE in LTE will be described. In LTE, cell reselection of an idle mode UE refers to the operations of selecting a camping cell, acquiring system information, maintaining synchronization, and receiving a paging signal by the UE. In order to understand the cell reselection operation, it is necessary to understand the cell reselection operation. Cell selection includes the operations of measuring and inducing (infra) Srxlev and checking if Srxlev is greater than zero (details are the same as the LTE standard and will therefore be omitted here). Here, srxlev consists of Qrxlevmeas, qrxlevmin, qrxlevminoffset and Pcompensation. Qrxlevmeas corresponds to a Reference Signal Received Power (RSRP) value measured by the UE, and other Qrxlevmin, qrxlevminoffset and Pcompensation are parameters that the gNB notifies to the UE through system information, radio Resource Control (RRC) messages, etc.

TABLE 1

Based on the above-described concept of suitable cells, i.e., srxlev >0, cell reselection is performed in LTE by the following operations. First, the UE measures signal strengths of a current camping cell (i.e., a serving cell) and neighbor cells, and then derives Rs and Rn. Here, qmeas, s and Qmeas, n denote signal strengths (RSRP) of the serving cell and the neighboring cell, respectively. In addition, qhyst, s and Qoffset, n are parameters that the gNB provides to the UE to prevent frequent cell reselection. After measuring the signal strength of the cell, the UE selects a cell having the highest Rs or Rn among cells having Srxlev greater than zero and then performs camping on the selected cell. If the currently camping cell and the newly selected cell are different from each other, this means that the UE performs cell reselection.

TABLE 2

The above description is a cell reselection procedure for idle mode UEs in LTE. Meanwhile, in the inactive mode newly introduced in NR, it is advantageous for the UE to stay in the cell having the valid C-RNTI as long as possible in view of the fast data transmission/reception of the inactive mode UE. In view of this, a cell reselection operation suitable for fast data transmission/reception of an inactive mode UE is proposed. In this disclosure, the term "cell" may be used interchangeably with base station, gNB, or eNodeB (eNB), all having the same meaning.

The present disclosure proposes a method for allowing an inactive mode UE to stay in a gNB with a C-RNTI valid for the UE for as long as possible by applying an additional offset to the gNB in a cell reselection regardless of whether a certain cell is a serving cell or a neighbor cell.

Fig. 6 is a diagram illustrating a cell reselection method of an inactive mode UE according to an embodiment of the present disclosure.

Referring to fig. 6, for a gNB 610 with a valid C-RNTI for an inactive mode UE, the UE adds an additional offset QC-RNTI in the cell reselection and applies it to cell ordering. On the other hand, for the gNB 620 without a valid C-RNTI for the inactive mode UE, the UE performs cell ordering without additional offset.

The basic cell reselection operation is the same as described above. In the case where the gNB has a valid C-RNTI for the inactive mode UE, the UE may apply an additional offset (referred to herein as QC-RNTI) as shown in FIG. 6. According to the present disclosure, for a gNB without a valid C-RNTI for an inactive mode UE, the UE does not apply an additional offset (QC-RNTI). The cell reselection equation according to the present disclosure is as follows.

TABLE 3

Alternatively, the cell reselection equation according to the present disclosure is as follows.

TABLE 4

The inactive-mode UE performs a cell reselection operation according to the above equation in the following three cases as shown in fig. 7 to 9.

Fig. 7 is a diagram illustrating a cell reselection operation in the case where an inactive mode UE moves from a gNB with a valid C-RNTI to a gNB without a valid C-RNTI, according to an embodiment of the present disclosure.

Referring to fig. 7, assume that the UE is currently camped on a gNB 710 with a valid C-RNTI. In view of fast data transmission/reception, it is advantageous for the UE to remain in the current serving cell (i.e., the gNB 710 with valid C-RNTI) for as long as possible according to the present disclosure. Thus, when Rs of the current serving cell is derived in the ranking procedure for cell reselection, the UE adds QC-RNTI, s in addition to Qmeas, s and Qhyst, s.

However, since the gNB 720 to which the UE is moving does not have a valid C-RNTI for the UE, the UE does not apply any additional offset other than Qmeas, n and Qoffset, n. In this example, the inactive-mode UE derives Rs and Rn in this way and compares them to perform the final cell reselection.

TABLE 5

Fig. 8 is a diagram illustrating a cell reselection operation in a case where an inactive mode UE moves from a gNB with no valid C-RNTI to a gNB with a valid C-RNTI, according to an embodiment of the present disclosure.

Referring to fig. 8, assume that the UE currently resides on the gNB 820 without a valid C-RNTI. In view of fast data transmission/reception, it is advantageous for the UE to remain in the neighbor cell (i.e., the gNB 810 with valid C-RNTI) for as long as possible, not in the current serving cell (i.e., the gNB 820 without valid C-RNTI) according to the present disclosure. Thus, when deriving Rs of the current serving cell in the ranking procedure for cell reselection, the UE does not apply any additional offset other than Qmeas, s and Qhyst, s.

However, since the gNB 810 to which the UE is moving does not have a valid C-RNTI for the UE, the UE adds QC-RNTI, n in addition to Qmeas, n and Qoffset, s, n. In this example, the inactive-mode UE derives Rs and Rn in this way and compares them to perform the final cell reselection.

TABLE 6

Fig. 9 is a diagram illustrating a cell reselection operation in a case where an inactive mode UE moves from a gNB with no valid C-RNTI to another gNB with no valid C-RNTI, according to an embodiment of the present disclosure.

Referring to fig. 9, assume that the UE currently resides on the gNB 920 without a valid C-RNTI. When performing cell reselection between a gNB with a C-RNTI and a gNB without a C-RNTI, the present disclosure produces an effect different from that of the conventional method. Thus, in the case of fig. 9, the cell reselection operation is similar to the conventional operation. That is, when Rs of the current serving cell is derived in the ranking procedure for cell reselection, the UE does not apply any additional offset other than Qmeas, s and Qhyst, s. Furthermore, the UE does not apply any additional offset other than Qmeas, n and Qhyst, n when deriving the Rn of the neighboring cell. In this example, the inactive-mode UE derives Rs and Rn in this way and compares them to perform the final cell reselection.

TABLE 7

Fig. 10 is a diagram illustrating a cell reselection operation in the case where an inactive mode UE moves from a gNB with a valid C-RNTI to another gNB with a valid C-RNTI, according to an embodiment of the present disclosure.

In an environment where cooperative transmission/reception is performed, a plurality of base stations may have a C-RNTI. In this case, the UE may also apply additional offsets other than Qmeas, s and Qhyst, s when deriving the Rs of the current serving cell in the ranking procedure for cell reselection. In addition, when deriving Rn of the neighboring cell, the UE may apply additional offsets other than Qmeas, n and Qoffset, s, n. In this example, the inactive-mode UE derives Rs and Rn in this way and compares them to perform the final cell reselection.

TABLE 8

In the present disclosure, a method is presented for allowing a UE to stay in a gNB with a valid C-RNTI for as long as possible by applying an additional offset to the gNB with the valid C-RNTI when an inactive mode UE performs cell reselection. Although a gNB with a valid C-RNTI is illustratively used in this disclosure, this disclosure may be extended to any base station. Here, such a base station includes the following examples.

Example 1: macrocell

Example 2: household district (HeNB)

Example 3: specific cells allocated to UE by base station through system information or RRC signaling

Example 4: cells using a particular frequency (e.g. 6GHz, or lower or higher)

Example 5: cells installed and operated by a particular operator

Thus, when applying the present disclosure, the UE may preferentially perform cell reselection of the cell as described above.

< second embodiment >

As smartphones appear, the traffic of smartphones grows exponentially and the demand for increased battery life of smartphones continues to grow. This means that an efficient power saving (power saving) technique is required, and thus a power saving mode operation of the terminal is required. Various technologies have been proposed and standardized so that terminals can operate more frequently in a power saving mode and reestablish network connections more quickly.

In order to achieve higher data transmission rates, fifth generation (5G) communication systems consider implementations in the ultra-high frequency (mmWave) band (e.g., such as the 60GHz band). In order to avoid path loss of radio waves and increase a transmission distance of radio waves at an ultra-high frequency band, various techniques such as beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antennas are discussed in 5G communication systems.

In addition, in order to improve the network of the 5G communication system, technical development is being conducted in advanced small cells, cloud radio access networks (cloud RANs), ultra dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, cooperative multipoint (CoMP), reception interference cancellation, and the like.

Furthermore, in the 5G communication system, hybrid frequency shift key and quadrature amplitude modulation (FQAM) and Sliding Window Superposition Coding (SWSC) are developed as Advanced Code Modulation (ACM) schemes, and Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA), and Sparse Code Multiple Access (SCMA) are also developed as advanced access technologies.

In a communication system, a terminal needs an initial cell selection method and a cell reselection method in an idle mode to select an optimal base station access. Further, in the connected mode, the terminal should perform Radio Resource Management (RRM) measurements in order to perform handover to move to a better cell. In order to select cells and compare the performance of the cells, each terminal should be able to observe or calculate a value representing or derived from the measured value of each cell. To achieve this, in LTE, different base stations reserve orthogonal resources in a shared frequency band using omni-beams and transmit cell-specific reference signals for each cell. The terminal measures the signal so as to know the Reference Signal Received Power (RSRP) of each cell.

Further, in the next generation communication system considering the beamforming, various methods are required in which different base stations transmit cell and beam-specific reference signals on different resources while using different beams and a terminal derives a representative value corresponding to a certain cell by using measured values of a plurality of beams transmitted in the cell.

Further, when the base station transmits two or more types of reference signals generated by different signal generation rules using two or more beams having different beam areas, coverage areas, transmission periods, and the like, a method for deriving a representative value corresponding to a certain cell has not been studied.

The present disclosure relates to next generation wireless communication systems, and more particularly, to systems, methods, and apparatuses for performing cell measurement and mobility management operations using signals transmitted through beamforming in a beamforming-based system including one or more base stations and one or more terminals.

Further, the present disclosure relates to a procedure for performing beam measurement, beam measurement report, and handover start in a wireless system having a base station and a terminal each using a plurality of antennas.

The present disclosure provides a method for a beam measuring entity (i.e., a terminal) to derive a representative value of the beam using entity (i.e., a base station) by using observed and measured beam information in wireless communication having a base station and a terminal each using a plurality of antennas, particularly in a system and environment of beam forming using the plurality of antennas, and also provides a trigger condition for transmitting a beam measurement report by using the derived representative value of the beam using entity.

The present disclosure provides a triggering condition for a beam-using entity (i.e., a base station) to transmit a signal for additional beam measurement to a beam-measuring entity (i.e., a terminal) by using a beam measurement value reported by the beam-measuring entity or a representative value of the beam-using entity, whether a specific condition is satisfied, or the like, in wireless communication having a base station and a terminal each using a plurality of antennas, particularly in a system and environment of beam forming using a plurality of antennas.

The present disclosure provides a procedure in which a beam measurement value reported by a beam measurement entity (i.e., a terminal) or a representative value of a beam usage entity (i.e., a base station), whether a specific condition is satisfied, etc., the beam usage entity exchanges information with a neighboring beam usage entity (i.e., a neighboring base station) related to the reporting of the beam measurement entity, thereby enabling the neighboring beam usage entity to transmit a signal for additional beam measurement in wireless communication having a base station and a terminal each using multiple antennas, particularly in a system and environment using beamforming of multiple antennas.

< method for transmitting and receiving two or more different types of reference signals >

Fig. 11 to 13 are diagrams illustrating methods for transmitting different types of reference signals according to various embodiments of the present disclosure.

Referring to fig. 11, as indicated by reference numeral 1100, different types of Reference Signals (RSs) having the same period may be transmitted using different frequency bands on the same time resource.

Referring to fig. 12, alternatively, as indicated by reference numeral 1200, different types of RSs having the same period may be transmitted using the same frequency band on different time resources.

Referring to fig. 13, alternatively, as indicated by reference numeral 1300, different types of RSs having different periods may be transmitted using the same frequency band on different time resources.

Furthermore, different types of reference signals having different periods may be transmitted using the same or different sequences on the same or different time and frequency resources.

< method for terminal to calculate cell measurement value >

Signals with different beam characteristics differ significantly in terms of received signal strength and transmission performance. For example, when a terminal receives a signal at the same location, a wide beam has lower RSRP and lower received signal quality (channel quality indicator (CQI), reference Signal Received Quality (RSRQ), signal-to-interference ratio (SINR), signal-to-noise ratio (SNR)) than a narrow beam because power is scattered.

As such, when different reference signals having different beam characteristics are transmitted by base station(s), antenna(s), or transmission point(s) in a cell, the terminal may measure the different reference signals. In this case, the reference signal measurement values may show relative differences according to beam characteristics as described above.

Fig. 14 is a diagram illustrating a method for a terminal to calculate measurement values of cells transmitting different reference signals according to an embodiment of the present disclosure.

Referring to fig. 14, the terminal may receive and measure all reference signals in operation S1410. Then, in operation S1420, the terminal may classify the received reference signals as the same type of Reference Signals (RSs). For example, the terminal may distinguish among a synchronization signal (synchronization signal, SS), a cell-specific Reference Signal (RS), and a beam-specific RS. In addition, the terminal may distinguish a signal having the same sequence generation rule and function from other signals.

Then, using the measured values of the classified reference signals, the terminal may calculate a cell representative value in operation S1430.

Thereafter, using the cell representative value, the terminal may select an idle mode cell or perform RRM measurement in operation S1440.

Fig. 15 is a diagram illustrating a method for classifying measurement signals into the same type of reference signals and calculating a cell representative value by using the measurement values according to an embodiment of the present disclosure.

Referring to fig. 15, a terminal may classify received signals by type. Then, the terminal may calculate a cell representative value 1500 by using the measured value of the classification signal, and use the calculated cell representative value for idle mode cell selection, connected mode RRM measurement, and the like.

There are various methods of calculating a cell representative value by using measurement results of the same type of signals transmitted on beams having the same characteristics. For example, the measurements may be summed, averaged, weighted summed, or weighted averaged. The measurement value may be a value obtained by scanning a base station beam and a terminal beam and applying L1 filtering or L3 filtering to the measurement result. In this case, the measured values may be calculated as a single value by a method such as summation, averaging, weighted summation, weighted averaging before and after L1 filtering or before and after L3 filtering, and then the cell representative value may be obtained through a subsequent process. Further, the measurements may be measured for each beam pair (beam pair), for the same base station beam, or for the same terminal beam. These methods can be equivalently used as a method of calculating a cell representative value by using only one type of signal according to the present patent.

Fig. 16 is a diagram illustrating a method of calculating a cell representative value by using all measured reference signals according to an embodiment of the present disclosure.

Referring to fig. 16, the cell representative value 1600 may be calculated by a method 1610 such as summing, averaging, weighted summing, or weighted averaging for a beam having the best signal strength, N beams having good signal strengths, or all beams. In this case, a measurement value may be calculated for each beam, and the above-described method for calculating a cell representative value may be used.

Fig. 17 is a diagram illustrating a method for calculating a cell representative value according to an embodiment of the present disclosure.

Referring to fig. 17, the terminal may identify the type of the classified reference signals, select one or more reference signal types, and calculate a cell representative value.

Specifically, the terminal may select reference signal type 1 in operation 1710 and calculate a cell representative value 1700 by using measured values of reference signals transmitted on various beams included in the selected type. Of course, the above-described method of calculating the cell representative value by using only the beams included in the same type of reference signal may be used.

Referring to fig. 17, a rule for a terminal to select a specific type of reference signal and calculate a representative value of a corresponding cell may have been determined in a system including the terminal and the base station. Thus, the terminal and the base station can know such rules in advance without requiring special information exchange and signaling. Such rules for selecting reference signals may be determined by considering one or more of the following examples:

if a specific type of reference signal beam prioritized in the standard is observed and measured, the terminal may calculate a cell representative value using only the specific type of reference signal beam. For example, when beam-specific reference signals (beam RS, additional RS, beam-forming demodulation RS (DM-RS), channel State Indicator (CSI) -RS (CSI-RS), etc.) are measured, the terminal may calculate to represent a cell representative value by using only the corresponding reference signal type.

Alternatively, if a reference signal type having a narrower beam width than other types is observed and measured, the terminal may prioritize (prioritize) the reference signal type having the narrowest beam width and calculate a cell representative value by using only the reference signal type.

Alternatively, if a reference signal type having a wider beam width than other types is observed and measured, the terminal may prioritize the reference signal type having the widest beam width and calculate the cell representative value by using only the reference signal type.

Alternatively, if reference signal types transmitted more frequently than other types are observed and measured, the terminal may prioritize the most frequently transmitted reference signal types and calculate the cell representative value by using only the reference signal types.

Alternatively, if a reference signal type transmitted more sparsely than other types is observed and measured, the terminal may prioritize the sparsely transmitted reference signal type and calculate the cell representative value by using only the reference signal type.

Alternatively, if the reference signal type transmitted in a wider coverage than other types is observed and measured, the terminal may prioritize the reference signal type transmitted in the widest coverage and calculate the cell representative value by using only the reference signal type.

Alternatively, if the reference signal type transmitted in a smaller coverage area than other types is observed and measured, the terminal may prioritize the reference signal type transmitted in the smallest coverage area and calculate the cell representative value by using only the reference signal type.

In another embodiment, the terminal may manage mobility by using only reference signals supported by different base stations (i.e., the serving base station and the target base station).

In addition, the base station may transmit a certain signal and participate in (configure) a corresponding determination to allow the terminal to select a specific type of reference signal.

Fig. 18 and 19 illustrate examples of signals transmitted by a base station to a terminal and used to calculate cell measurements according to embodiments of the present disclosure.

Referring to fig. 18, a signal transmitted by a base station to a terminal may include a preferred reference signal type 1810 and information 1820 on a method of determining a cell representative value by using the reference signal. For example, the information 1820 may include the number of beams (e.g., 1, K, all) to be used to determine the cell representative value, an index indicating the method used to select the beam (e.g., whether any beam or the best beam is selected), the type of equation used to calculate the cell representative value (e.g., sum, average, and weight sum for different K beams with different weights), etc.

The base station and the terminal may know in advance the index regarding the method for calculating the cell representative value as shown in table 9 below. In case of weighted summation, the base station should transmit the corresponding weights as shown in fig. 20.

TABLE 9 derivation index in base station transmission signal for cell representative value measured by terminal (derivation index for cell level measurement)

TABLE 9

Derivation method	Index
		Summing up	0
Average of	1
		Weighted summation	2

Referring to fig. 19, alternatively, signals transmitted by a base station to a terminal may include indexes 1910, 1920 and 1930 of preferred reference signal types and information 1940, 1950 and 1960 on a method of determining a cell representative value by using reference signals. For example, the information 1820 may include the number of beams (e.g., 1, K, all) to be used to determine the cell representative value, an index indicating the method used to select the beam (e.g., whether any beam or the best beam is selected), the type of equation used to calculate the cell representative value (e.g., sum, average, and weight sum for different K beams with different weights), etc. The base station and the terminal may know the index of each reference signal type in advance as shown in table 10 below.

Table 10 reference signal index (RS index for cell level measurement) for measuring cell representative value by terminal UE

The information may be included as an information element in a portion of a certain RRC message, as a media access control (medium access control, MAC) Control Element (CE) in a portion of a certain MAC message, or as a Physical (PHY) element in a certain PHY message.

Fig. 20 is a diagram illustrating an example of a signal including weights transmitted by a base station to a terminal according to an embodiment of the present disclosure.

Referring to fig. 20, the signal may include a preferred reference signal type 2010, the number 2020 of beams to be used, and information on a method 2030 for determining a cell representative value. In addition, any of the information described above in fig. 18 and 19 may be further included. Further, if the method for determining the cell representative value is weighted average or weighted summation, the base station may transmit the respective weights 2040 to the terminal.

Fig. 21 is a diagram illustrating a method in which a terminal calculates a cell representative value of each RS from different RSs through a separate procedure according to an embodiment of the present disclosure.

Referring to fig. 21, the terminal can calculate cell representative values of the respective RSs through a separate procedure without mixing or selecting different beam measurement information received from different types of RSs. In this case, the filter and cell representative value calculation equations of the different types of RSs may be the same or different.

If different filter and cell representative value calculation equations are used for different types of RSs, the base station may transmit this information to the terminal to perform the filter and cell representative value calculation.

Fig. 22 is a diagram illustrating a method of controlling a change in mobility by using different types of reference signals according to an embodiment of the present disclosure.

Referring to fig. 22, the ue (i.e., terminal) may report a measurement result of the reference signal type 1 in operation S2210.

Based on the measurement result, the gNB (i.e., the base station) may determine whether reference signal type 2 needs to be transmitted in operation S2220.

If it is determined that reference signal type 2 needs to be transmitted, the gNB may transmit reference signal type 2 to the UE in operation S2230. Then, the gNB may receive a measurement result of the reference signal type 2 in operation S2240.

In operation S2250, the gNB determines whether mobility change (handover, etc.) is required based on the measurement result. The gNB may request or indicate a mobility change in operation S2260, if necessary.

At this time, the gNB may determine a cell representative value by using values measured through different types of reference signals according to the above-described method or a method to be described below, and then determine whether mobility change is required by using the representative value.

Fig. 23-28 illustrate various embodiments in accordance with various embodiments of the present disclosure, wherein different numbers (N1, N2,..nk) of beam measurement signals are selected for different types of Reference Signals (RSs) in order of optimal performance, and then cell representative values are derived by multiplying the selected signals by different weights. The weight may be positive or negative and may be greater than or less than 1.

Referring to fig. 23, a method for calculating representative values 2310 and 2320 of respective RSs through a separate procedure for different types of RSs, and then determining one cell representative value by using the above-described representative values is illustrated. Referring to fig. 23, the ue may determine a cell representative value by multiplying the measured value determined for each RS by a weight.

Referring to fig. 24, a method for multiplying each beam measurement signal by the same weight 2410 for the same type of RS and then determining a cell representative value 2420 is illustrated. On the other hand, different weights (weight 1 and weight 2) may be applied for different types of RSs. However, the weight 1 and the weight 2 may be the same value.

Referring to fig. 25, a method for selecting a specific number of beam measurement signals for different types of RSs, multiplying a representative value of each RS by a weight, thereby deriving a cell representative value is shown. Referring to fig. 25, the ue may select N1 best beams 2510 and N2 best beams 2520 for the additional RS and the idle mode RS, respectively, and then determine representative values 2530 and 2540 of the respective RSs. Further, the UE may calculate a cell representative value 2550 by applying a weight to the representative value of each RS.

Referring to fig. 26, a method for selecting a specific number of beam measurement signals for different types of RSs, calculating a representative value of each RS type by multiplying each selected beam measurement signal by a weight, and deriving a cell representative value by multiplying the representative value of each RS type by the weight is illustrated. In this case, the weights applied to the respective beam measurement signals may be different from or equal to each other.

Referring to fig. 26, the ue selects N1 best beams 2610 and N2 best beams 2620 for the additional RS and the idle mode RS, respectively, multiplies each selected beam measurement signal by a corresponding weight 2630 or 2640, and determines a representative value 2650 or 2660 for each RS type. Then, the UE may calculate a cell representative value 2670 by applying a weight to the representative value of each RS type.

Fig. 27 illustrates another method for selecting a different number of beam measurement signals for different types of RSs and then deriving a cell representative value by multiplying the selected signals by different weights, according to an embodiment of the present disclosure.

Referring to fig. 27, the ue may select N1 best beams 2710 and N2 best beams 2720 for the additional RS and the idle mode RS, respectively, and multiply each selected beam measurement signal by a corresponding weight 2730 or 2740. Then, using the result, the UE may calculate a cell representative value 2770. In this case, the weights applied to the respective beam measurement signals may be different from or equal to each other.

Fig. 28 is a diagram illustrating a method for deriving a cell representative value by multiplying all beam measurement signals by different weights for different types of RSs according to an embodiment of the present disclosure.

Referring to fig. 28, the ue may multiply each of all beam measurement signals for the additional RS and the idle mode RS by a corresponding weight 2810 or 2820. Then, using the result, the UE may calculate a cell representative value 2830. In this case, the weights applied to the respective beam measurement signals may be different from or equal to each other.

Fig. 29 is a diagram illustrating a method of controlling mobility change by using different types of reference signals according to an embodiment of the present disclosure.

Referring to fig. 29, the ue may receive a reference signal type 1 from each of the first and second gNB base stations in operations S2910 and S2920 and then report the measurement result to the first gNB in operation S2930.

Based on the measurement result, the first gNB may determine whether reference signal type 2 needs to be transmitted in operation S2940. If it is determined that it is necessary, the first gNB may request the reference signal type 2 from the second gNB in operation S2950.

Thus, in operation S2960, the second gNB may recognize the necessity of transmitting the reference signal type 2. Then, in operations S2970 and S2975, each of the first and second gnbs may transmit the reference signal type 2 to the UE. Accordingly, the UE may transmit the measurement result of the reference signal type 2 to the first gNB in operation S2980. Then, in operation S2985, the first gNB may determine whether the mobility needs to be changed based on the measurement result. The first gNB may send a request or instruction for mobility change to the UE in operation S2990, if necessary.

< measurement report trigger event Using measurement values of different RSs >

[ event NR1]

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[ event NR2]

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The following table is divided into several pages showing a description of event NR 3.

[ event NR3]

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[ event NR4]

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The following table is divided into several pages showing a description of event NR 5.

[ event NR5]

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The following table is divided into several pages showing a description of event NR 6.

[ event NR6]

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The following table is divided into several pages showing a description of event NR 7.

[ event NR7]

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Fig. 30 is a diagram illustrating a terminal according to an embodiment of the present disclosure.

Referring to fig. 30, the terminal 3000 may include a transceiver 3010 for transmitting and receiving signals, and a controller 3030.

Terminal 3000 can transmit and/or receive signals, information, messages, etc. via transceiver 3010. For example, when a controller is defined in the specification, it can be said that "the controller may be a circuit, an application specific integrated circuit, or at least one processor.

The controller 3030 may control the overall operation of the terminal 3000. The controller 3030 may include at least one processor. The controller 3030 may control the operation of the terminal described in the embodiments of the present disclosure. For example, the controller 3030 may control the signal flow in the flowcharts described above.

Fig. 31 is a diagram illustrating a base station according to an embodiment of the present disclosure.

Referring to fig. 31, a base station 3100 may include a transceiver 3110 for transmitting and receiving signals, and a controller 3130. For example, when a controller is defined in the specification, it can be said that "the controller may be a circuit, an application specific integrated circuit, or at least one processor.

The base station 3100 may transmit and/or receive signals, information, messages, etc. via the transceiver 3110.

The controller 3130 may control the overall operation of the base station 3100. The controller 3130 may include at least one processor. The controller 3130 may control the operation of the base station described in the embodiments of the present disclosure. For example, the controller 3130 may control the signal flow in the above-described flowcharts.

< third embodiment >

Meanwhile, in case that a reference signal for both the idle mode UE and the connected mode UE (hereinafter referred to as idle mode RS) and a reference signal for only the connected mode UE (hereinafter referred to as connected mode RS) coexist, the UE may perform RRM measurement through the idle mode RS and then (a) request the connected mode RS at an appropriate time, or (b) report the connected mode RS measurement result to the gNB when the gNB transmits the connected mode RS at an appropriate time. The present disclosure provides related operations.

Fig. 32 is a flowchart illustrating an initial access operation according to an embodiment of the present disclosure.

Referring to fig. 32, in an RRC connection setup procedure, the present disclosure proposes a method regarding (a) when a UE requests a gNB to transmit a connection mode RS, (b) when the gNB transmits a connection mode RS, and (c) when the gNB allocates resources for a connection mode RS measurement report of the UE. This operation proposed by the present disclosure is based on fig. 32.

That is, based on the random access procedure and the RRC connection procedure shown in operations S3210 to S3260 of fig. 32, the UE may request transmission of the connection mode RS, and the gNB may transmit the connection mode RS and allocate resources for the connection mode RS measurement report of the UE. Details will be described below.

< request connection pattern RS >

In operation S3220, the UE may request the gNB to transmit the connection mode RS through preamble classification when transmitting the random access preamble.

For this, the random access preambles are classified into two groups. If the UE transmits a random access preamble belonging to one group, the gNB learns of the request for the connection mode RS. If the UE transmits a random access preamble belonging to another group, the gNB learns that there is no request for a connection mode RS.

In case of requesting the connection mode RS, the UE continuously performs blind decoding on a Physical Downlink Control Channel (PDCCH) to learn allocation information about resources for transmitting the connection mode RS by the gNB and resources for transmitting the related measurement result report by the UE.

Alternatively, when transmitting the RRC connection request message in operation S3240, the UE may set a bit indicating a request to transmit the connection mode RS to 1 in the above message in order to request the gNB to transmit the connection mode RS.

If the corresponding bit is set to 0, the gNB learns that the UE does not request to transmit a connection mode RS.

Alternatively, when transmitting the RRC connection setup complete message in operation S3260, the UE may set a bit indicating a request to transmit the connection mode RS to 1 in the above message in order to request the gNB to transmit the connection mode RS.

< allocation of connection-mode RS resources >

When the random access response message is transmitted in operation S3230, the gNB allocates resources for transmitting the connection mode RS in the above message.

Alternatively, when the RRC connection setup message is transmitted in operation S3250, the gNB allocates resources for transmitting the connection mode RS in the above message.

Here, the allocated resources are time/frequency resources, and may be expressed as resource block indexes or the like.

Alternatively, the gNB allocates resources for transmitting the connection mode RS through a separate signal, e.g., PDCCH Downlink Control Information (DCI).

< allocation of connection-mode RS measurement feedback resources >

When the random access response message is transmitted in operation S3230, the gNB allocates resources for reporting the connection mode RS measurement result in the above message.

Alternatively, when the RRC connection setup message is transmitted in operation S3250, the gNB allocates resources for reporting the connection mode RS measurement result in the above message.

Alternatively, the gNB allocates resources for reporting the connection mode RS measurement result through a separate signal (e.g., PDCCH DCI).

< feedback of connection mode RS measurement results >

When transmitting the RRC connection request message in operation S3240, the UE may insert information about the connection mode RS measurement result in the above message.

Here, the connection mode RS measurement result includes N beam indexes having the highest signal strengths after the connection mode RS measurement and corresponding signal strengths (RSRP or RSRQ). Here, N may be set by the gNB through an RRC message or the like.

Alternatively, when the RRC connection setup complete message is transmitted in operation S3260, the UE may insert connection mode RS measurement result information into the above-described message.

Alternatively, the UE transmits the connected pattern RS measurement result information to the gNB through a separate signal, e.g., a Physical Uplink Control Channel (PUCCH), a Physical Uplink Shared Channel (PUSCH), etc.

Fig. 33 is a flowchart illustrating a handover operation according to an embodiment of the present disclosure.

Referring to fig. 33, the present disclosure proposes a method regarding (a) when a UE requests a gNB to transmit a connection mode RS, (b) when the gNB transmits the connection mode RS, and (c) when the gNB allocates resources for a connection mode RS measurement report of the UE during handover. This operation proposed by the present disclosure is based on fig. 33.

That is, based on the handover procedure shown in S3310 to S3370 of fig. 33, the UE may request transmission of the connection mode RS, and the gNB may transmit the connection mode RS and allocate resources for the connection mode RS measurement report of the UE. Details will be described below.

< request connection pattern RS >

When transmitting the measurement report in operation S3320, the UE sets a bit indicating a request to transmit the connection mode RS to 1 in the above message so as to request the gNB to transmit the connection mode RS. In operation S3330, the source gNB and the target gNB may initiate a handover request and respond.

Alternatively, when transmitting the random access preamble in operation S3350, the UE requests the gNB to transmit the connection pattern RS through preamble classification.

Alternatively, when transmitting the RRC connection reconfiguration complete message in operation S3370, the UE sets a bit indicating a request to transmit the connection mode RS to 1 in the above message in order to request the gNB to transmit the connection mode RS.

< allocation of connection-mode RS resources >

When an RRC connection reconfiguration (or mobility control information or handover command) message is transmitted in operation S3340, the gNB allocates resources for transmitting the connection mode RS in the above message.

Alternatively, when the random access response message is transmitted in operation S3360, the gNB allocates resources for transmitting the connection mode RS in the above message.

Alternatively, the gNB allocates resources for transmitting the connection mode RS through a separate signal (e.g., PDCCH DCI).

< allocation of connection-mode RS measurement feedback resources >

When an RRC connection reconfiguration (or mobility control information or handover command) message is transmitted in operation S3340, the gNB allocates resources for reporting the connection mode RS measurement result in the above message.

Alternatively, when the random access response message is transmitted in operation S3360, the gNB allocates resources for reporting the connection mode RS operation measurement result in the above message.

< feedback of connection mode RS measurement results >

When transmitting the RRC connection reconfiguration complete message in operation S3370, the UE inserts connection mode RS measurement result information into the above-described message.

Alternatively, the UE transmits the connection mode RS measurement result information to the gNB via a separate signal (e.g., PUCCH, PUSCH, etc.).

According to yet another example, the operation set forth in the present disclosure is based on fig. 34.

Fig. 34 is a flowchart illustrating operation according to an embodiment of the present disclosure.

Referring to fig. 34, in operation S3410 of transmitting the RRC connection setup request, the UE may request the source gNB to receive an additional RS from the target gNB. The source gNB may transmit a request for additional RS scheduling to the target gNB in operation S3420, and may receive a response in operation S3430. Accordingly, in response to the RRC connection setup request, the source gNB may transmit a response message to the UE in operation S3440. The message may include scheduling information for the additional RS. At this time, the additional RS may refer to, for example, CSI-RS.

Accordingly, the UE may receive RSs from the source and target gnbs in operations S3450 and S3460.

The present disclosure contemplates a system where the gNB uses Synchronization Signals (SSs) and CSI-RSs together. Here, the SS may include a primary synchronization signal (primary synchronization signal, PSS) and a secondary synchronization signal (secondary synchronization signal, SSs). Further, the SS may correspond to a cell-specific signal, and the CSI-RS may be a cell-specific signal, a UE-specific signal, or a UE group-specific signal.

The present disclosure considers the case where a UE initially accesses a gNB or performs a handover from a serving gNB to a target gNB. Further, the present disclosure considers the case where the gNB uses the SS signal in determining whether the UE performs initial access or handover.

In this case, the present disclosure proposes a UE operation of promptly receiving allocation of beams to be used for data communication from an initially accessed gNB or a handover target gNB. In general, the beam of the transmitting SS may be a relatively wide beam in order to reduce the time required for beam scanning or any other reason. However, the beam used to transmit the CSI-RS or data may be a relatively narrow beam in order to obtain a high beamforming gain. Accordingly, the gNB or the UE may determine whether to perform initial access or handover through an SS transmitted on a wide beam, and the UE may identify a narrow beam to be used for data communication by receiving CSI-RS from the accessed gNB or target gNB.

Further, because it is not known when a UE will access the gNB, the SS may be considered an always-on (always-on) signal that is always sent. However, the CSI-RS may be an always on signal or not, depending on the overhead of time and frequency resources required for transmission. The present disclosure assumes that the SS is an always-on signal and the CSI-RS is not an always-on signal. That is, it is assumed that the gNB can determine whether to transmit the CSI-RS.

The present disclosure assumes that the SS transmits over a relatively wide beam and the CSI-RS transmits over a relatively narrow beam. The mapping relationship between the wide beam for SS transmission and the narrow beam for CSI-RS transmission may be established according to the antenna pattern of the gNB. The present disclosure assumes that this relationship is established. Examples are shown in the following table.

TABLE 11

The assumptions considered in this disclosure are as above. However, the present disclosure is not limited to the above, and may be generalized in the case of initial access and handover in a system in which two RSs are used together.

Fig. 35 to 41 are flowcharts illustrating various methods for determining beams for data transmission and reception in a handover process according to embodiments of the present disclosure;

referring to fig. 35, the operation of the present disclosure will be described in the case where the UE performs a handover from the serving gNB to the target gNB.

1. Referring to fig. 35, the service gNB provides measurement configuration information to the UE in operation S3510.

A. Here, the measurement configuration information includes a frequency to be measured by the UE, a measurement report trigger condition, and the like.

The ue performs measurement based on measurement configuration information received from the serving gNB.

A. Here, the UE measures signal strength or quality of SSs transmitted from the serving gNB and the target gNB.

B. In this disclosure, it is assumed that each gNB transmits an SS while scanning multiple beams pointing in different directions. Thus, the UE can distinguish between SSs transmitted through different beams by time and frequency resources for receiving the SSs.

3. If any event that the signal strength of the target gNB is greater than the signal strength of the service gNB is detected through the comparison of the signal strengths in operation S3520, the UE transmits a measurement report to the service gNB in operation S3540.

A. To transmit the measurement report, the UE may transmit and receive a scheduling request (scheduling request, SR), a buffer status report (buffer status report, BSR), an Uplink (UL) grant, etc. to and from the serving gNB in operation S3530.

B. Although an A3 event is described, for example, the same principles can be applied to other events.

4. When receiving the measurement report from the UE, the serving gNB transmits a handover request to the target gNB to perform admission control in operation S3550.

A. If the target gNB can accept the UE, the target gNB transmits an Acknowledgement (ACK) for the handover request to the serving gNB and provides information required for the UE to access the target gNB in operation S3550.

This information required for the UE to access the target gNB includes a dedicated random access preamble (random access preamble, RAP) for the UE to synchronize uplink with the target gNB, and a necessary C-RNTI for data transmission/reception between the UE and the target gNB.

5. In operation S3560, the serving gNB transmits a handover command to the UE to provide information required for the UE to access the target gNB.

Here, the handover command may include a dedicated RAP and a C-RNTI received from the target gNB through the handover request ACK.

6. Based on the information included in the handover command, the UE transmits the RAP to the target gNB in operation S3570.

A. This is an operation for the UE to control Transmission (TX) timing and power for performing uplink transmission/reception with the target gNB.

7. After receiving the RAP from the UE, the target gNB transmits a random access response (random access response, RAR) to the UE in operation S3580.

A. After receiving the RAP, the target gNB informs the UE of the TX timing and power adjustment level through the RAR and requests the UE to send the RAP again if necessary. After the uplink synchronization, the target gNB allocates an Uplink (UL) grant so that the UE can transmit a handover confirm in operation S3580.

8. The UE having uplink synchronization receives the RAR and transmits a handover confirm to the target gNB through UL grant included in the RAR in operation S3590.

A. By doing so, the UE completes the handover from the serving gNB to the target gNB.

The above-described handover operation is designed for the case where only one RS is used by the gNB. This is not applicable to the case considered in the present disclosure, that is, the case where determining whether to perform a handover is based on an SS transmitted on a wide beam, but actual data transmission/reception uses a narrow beam. The inapplicability is because the UE cannot determine a narrow beam to be used for transmitting and receiving data to and from the target gNB despite the completion of the handover.

In the present disclosure, a UE determines whether to perform a handover by measuring an SS transmitted on a wide beam and then performs measurement of CSI-RS transmitted on a narrow beam during a handover procedure in order to find a narrow beam to be used with a target gNB as soon as possible. Hereinafter, various embodiments will be described.

[ handover: proposal 1]

Referring to fig. 36, a description will be given of [ handover: the embodiment of proposal 1.

1. In operation S3610, the service gNB provides measurement configuration information to the UE.

3. If any event that the signal strength of the target gNB is greater than the signal strength of the service gNB is detected through the comparison of the signal strengths in operation S3620, the UE transmits a measurement report to the service gNB in operation S3640.

4. When receiving the measurement report from the UE, the serving gNB transmits a handover request to the target gNB to perform admission control in operation S3650.

5. In operation S3660, the serving gNB transmits a handover command to the UE to provide information required for the UE to access the target gNB.

6. Based on the information included in the handover command, the UE transmits RAP to the target gNB in operation S3670.

Here, the target gNB may receive RAPs of the UE while scanning a wide beam for transmitting the SS. In this case, the target gNB stores the wide beam for receiving the RAP of the UE and uses it in the next step. If the target gNB receives the RAPs of the UE through a plurality of wide beams, the target gNB stores the wide beam having the highest signal strength and uses it in the next step.

7. After receiving the RAP from the UE, the target gNB transmits the RAR to the UE in operation S3680.

A. After receiving the RAP, the target gNB informs the UE of the TX timing and power adjustment level through the RAR and requests the UE to send the RAP again if necessary. After this uplink synchronization, the target gNB allocates UL grant so that the UE can send a handover acknowledgement.

B. In addition, in the present disclosure, the target gNB transmits CSI-RS configuration information 3600 to the UE along with the RAR. Details of the CSI-RS configuration information will be described after the entire operation description.

8. The target gNB transmits the CSI-RS through a plurality of narrow beams corresponding to the wide beam for receiving RAP in operation S3690.

9. Based on the CSI-RS configuration information, the UE measures the signal strength or quality of the CSI-RS sent by the target gNB.

10. In operation S3691, the UE having uplink synchronization receives the RAR and transmits a handover confirm to the target gNB through UL grant included in the RAR.

A. When transmitting the handover acknowledgement, the UE also transmits feedback 3601 for the measurement result of the CSI-RS. At this time, the UE uses UL grant included in the RAR.

By doing so, the UE completes the handover from the serving gNB to the target gNB.

11. Based on the CSI-RS feedback of the UE, the target gNB selects and informs the UE of a narrow beam to be used by the UE in operation S3692.

In the present disclosure, the target gNB provides CSI-RS configuration information to the UE. This is similar to CSI-RS configuration information used in LTE. In addition, the target gNB needs to inform the UE of beam information for transmitting the CSI-RS. Accordingly, the target gNB may insert SS beam information for receiving RAPs in the CSI-RS configuration information, or may insert corresponding CSI-RS beam information. Table 11 and table 12 below show examples of CSI-RS configuration information including antenna port information, time and frequency resource information, subframe information, power information, wide SS beam information for receiving RAPs, narrow SS beam information to be used for transmitting CSI-RS, CSI-RS transmission period, and CSI-RS configuration valid time.

TABLE 12

Tables 13 to 16 below show methods for determining CSI-RS transmission periods, offsets, and resource positions in CSI-RS configuration information used in the present disclosure. The CSI-RS transmission period, offset, resource location, and power information (p-C) may be determined according to CSI-RS configuration information and the following table.

TABLE 13 CSI reference Signal subframe configuration

TABLE 14 mapping from CSI reference signal configuration to (k ', l') for normal cyclic prefix

Note that: n is n _s '＝n _s mod 2. Configurations 0-19 of normal subframes may be used for frame structure types 1, 2, and 3. Configurations 20-31 and the configuration of special subframes are only applicable to frame structure type 2.

Table 15 mapping from CSI reference signal configuration to (k ', l') for extended cyclic prefix.

Note that: n is n _s '＝n _s mod 2. Configurations 0-15 of normal subframes may be used for frame structure type 1 and type 2. Configurations 16-27 and the configuration of special subframes are only available for frame structure type 2.

TABLE 16

In addition, in the present disclosure, the UE transmits feedback 3601 for the measurement result of the CSI-RS to the target gNB. Table 17 below shows feedback content of the UE.

TABLE 17

[ handover: proposal 2]

Referring to fig. 37, a description will be given of [ handover: the embodiment of proposal 2.

1. In operation S3710, the serving gNB provides measurement configuration information to the UE.

3. If any event that the signal strength of the target gNB is greater than the signal strength of the service gNB is detected through the comparison of the signal strengths in operation S3720, the UE transmits a measurement report to the service gNB in operation S3740.

4. When receiving the measurement report from the UE, the serving gNB transmits a handover request to the target gNB to perform admission control in operation S3750.

5. In operation S3760, the serving gNB transmits a handover command to the UE to provide information required for the UE to access the target gNB.

6. Based on the information included in the handover command, the UE transmits the RAP to the target gNB in operation S3770.

7. After receiving the RAP from the UE, the target gNB transmits the RAR to the UE in operation S3780.

B. In addition, in the present disclosure, the target gNB transmits CSI-RS configuration information 3700 to the UE along with the RAR. Details of the CSI-RS configuration information are described above.

8. The target gNB transmits the CSI-RS through a plurality of narrow beams corresponding to the wide beam for receiving RAP in operation S3790.

10. The UE having uplink synchronization receives the RAR and transmits a handover confirm to the target gNB through UL grant included in the RAR in operation S3791.

11. In operation S3792, the target gNB allocates UL grant for feedback of CSI-RS measurement results to the UE.

12. In operation S3793, the UE transmits feedback of the CSI-RS measurement result to the target gNB using the allocated UL grant.

13. Based on the CSI-RS feedback of the UE, the target gNB selects and informs the UE of a narrow beam to be used by the UE in operation S3794.

[ handover: proposal 3]

Referring to fig. 38, a description will be given of [ handover: the embodiment of proposal 3 ].

1. In operation S3810, the service gNB provides measurement configuration information to the UE.

3. If any event that the signal strength of the target gNB is greater than the signal strength of the service gNB is detected through the comparison of the signal strengths in operation S3820, the UE transmits a measurement report to the service gNB in operation S3840.

4. When receiving the measurement report from the UE, the serving gNB transmits a handover request to the target gNB to perform admission control in operation S3850.

A. In the present disclosure, the service gNB delivers information contained in the measurement report to the target gNB. The information includes SS beam index and corresponding signal strength of the target gNB measured by the UE.

B. Further, the target gNB determines CSI-RS configuration based on measurement reports received from the serving gNB, and then delivers it to the serving gNB through a handover request ACK.

5. In operation S3860, the serving gNB transmits a handover command to the UE to provide information required for the UE to access the target gNB.

A. In addition, in the present disclosure, the serving gNB transmits CSI-RS configuration information 3800 to the UE together with a handover command. Details of the CSI-RS configuration information are described above.

6. Based on the information included in the handover command, the UE transmits RAP to the target gNB in operation S3870.

7. After receiving the RAP from the UE, the target gNB transmits the RAR to the UE in operation S3880.

8. The target gNB transmits the CSI-RS through a plurality of narrow beams corresponding to the wide beam for receiving RAP in operation S3890.

10. The UE having uplink synchronization receives the RAR and transmits a handover confirm to the target gNB through UL grant included in the RAR in operation S3891.

A. When transmitting the handover acknowledgement, the UE also transmits feedback 3801 for the measurement result of the CSI-RS. At this time, the UE uses UL grant included in the RAR.

11. Based on the CSI-RS feedback of the UE, the target gNB selects and informs the UE of a narrow beam to be used by the UE in operation S3892.

[ handover: proposal 4]

Referring to fig. 39, a description will be given of [ handover: the embodiment of proposal 4 ].

1. In operation S3910, the service gNB provides measurement configuration information to the UE.

3. If any event that the signal strength of the target gNB is greater than the signal strength of the serving gNB by an offset is detected through the comparison of the signal strengths in operation S3920, the UE transmits a measurement report to the serving gNB in operation S3940.

4. When receiving the measurement report from the UE, the serving gNB transmits a handover request to the target gNB to perform admission control in operation S3950.

5. In operation S3960, the serving gNB transmits a handover command to the UE to provide information required for the UE to access the target gNB.

A. In addition, in the present disclosure, the serving gNB transmits CSI-RS configuration information 3900 to the UE along with the handover command. Details of the CSI-RS configuration information are described above.

6. The target gNB transmits CSI-RS through a plurality of narrow beams corresponding to the wide beam having the highest signal strength measured by the UE and included in the measurement report in operation S3970.

7. Based on the CSI-RS configuration information, the UE measures the signal strength or quality of the CSI-RS sent by the target gNB.

8. Based on the information included in the handover command, the UE transmits the RAP to the target gNB in operation S3980.

9. After receiving the RAP from the UE, the target gNB transmits the RAR to the UE in operation S3990.

10. The UE having uplink synchronization receives the RAR and transmits a handover confirm to the target gNB through UL grant included in the RAR in operation S3991.

A. When transmitting the handover acknowledgement, the UE also transmits feedback 3901 for the measurement result of the CSI-RS. At this time, the UE uses UL grant included in the RAR.

11. Based on the CSI-RS feedback of the UE, the target gNB selects and informs the UE of a narrow beam to be used by the UE in operation S3992.

[ handover: proposal 5]

Referring to fig. 40, a description will be given of [ handover: the embodiment of proposal 5.

1. In operation S4010, the service gNB provides measurement configuration information to the UE.

3. If any event that the signal strength of the target gNB is greater than the signal strength of the service gNB by an offset is detected through the comparison of the signal strengths in operation S4020, the UE transmits a measurement report to the service gNB in operation S4040.

4. When receiving the measurement report from the UE, the serving gNB transmits a handover request to the target gNB to perform admission control in operation S4050.

5. In operation S4060, the serving gNB transmits a handover command to the UE to provide information required for the UE to access the target gNB.

A. In addition, in the present disclosure, the serving gNB transmits the CSI-RS configuration information 4000 to the UE together with the handover command. Details of the CSI-RS configuration information are described above.

6. Based on the information included in the handover command, the UE transmits the RAP to the target gNB in operation S4070.

7. After receiving the RAP from the UE, the target gNB transmits the RAR to the UE in operation S4080.

B. In addition, in the present disclosure, the RAR includes an indicator 4001 for instructing the UE to make CSI-RS measurements.

8. If the CSI-RS measurement order indicator included in the RAR is set to 1, the target gNB transmits the CSI-RS through a plurality of narrow beams corresponding to the wide beam for receiving the RAP in operation S4090.

A. If the CSI-RS measurement order indicator included in the RAR is set to 0, the target gNB does not transmit CSI-RS.

9. In addition, if the CSI-RS measurement order indicator included in the RAR is set to 1, the UE measures the signal strength or quality of the CSI-RS transmitted by the target gNB based on the CSI-RS configuration information transmitted with the handover command.

A. If the CSI-RS measurement order indicator included in the RAR is set to 0, the UE does not perform an operation related to CSI-RS measurement because the target gNB does not transmit CSI-RS.

10. The UE having uplink synchronization receives the RAR and transmits a handover confirm to the target gNB through UL grant included in the RAR in operation S4091.

A. When transmitting the handover acknowledgement, the UE also transmits feedback 4002 for the measurement result of the CSI-RS. At this time, the UE uses UL grant included in the RAR.

B. By doing so, the UE completes the handover from the serving gNB to the target gNB.

11. Based on the CSI-RS feedback of the UE, the target gNB selects and informs the UE of a narrow beam to be used by the UE in operation S4092.

[ handover: proposal 6]

Referring to fig. 41, a description will be given of [ handover: the embodiment of proposal 6 ].

1. In operation S4110, the service gNB provides measurement configuration information to the UE.

3. If any event that the signal strength of the target gNB is greater than the signal strength of the service gNB by an offset is detected through the comparison of the signal strengths in operation S4120, the UE transmits a measurement report to the service gNB in operation S4140.

4. When receiving the measurement report from the UE, the serving gNB transmits a handover request to the target gNB to perform admission control in operation S4150.

5. In operation S4160, the serving gNB transmits a handover command to the UE to provide information required for the UE to access the target gNB.

A. In addition, in the present disclosure, the serving gNB transmits CSI-RS configuration information 4100 to the UE along with a handover command. Details of the CSI-RS configuration information are described above.

6. Based on the information included in the handover command, the UE transmits the RAP to the target gNB in operation S4170.

7. After receiving the RAP from the UE, the target gNB transmits the RAR to the UE in operation S4180.

B. In addition, in the present disclosure, using RAR, the target gNB may instruct the UE to measure only a subset 4101 of CSI-RS transmission resources specified in the CSI-RS configuration.

C. Here, the target gNB may limit an antenna port for transmitting the CSI-RS in the information included in the CSI-RS configuration through the RAR and notify the UE of the limitation. For example, even if the previously transmitted CSI-RS configuration indicates four antenna ports, the target gNB may inform the UE that CSI-RS will be transmitted using only two antenna ports through the RAR.

D. Further, even if the previously transmitted CSI-RS configuration indicates M SS beams or CSI-RS beam sets, the target gNB may inform the UE through the RAR that CSI-RS will be transmitted only for N (< M) SS beams or CSI-RS beam sets.

E. Further, even if the previously transmitted CSI-RS configuration indicates M resource blocks, the target gNB may inform the UE that only N (< M) resource blocks will be used to transmit CSI-RS through the RAR.

F. Further, even if the previously transmitted CSI-RS configuration indicates M subframes as a period, the target gNB may inform the UE that the CSI-RS will be actually transmitted in the period of N (< M) subframes through the RAR.

G. In the present disclosure, CSI-RS configuration information is transmitted together with a handover command. At this time, the target gNB determines a CSI-RS configuration based on the signal strength of the target gNB included in the measurement report, and transmits it to the UE. However, the UE transmits the uplink RAP to the target gNB after receiving the handover command, so that the target gNB can more accurately identify the CSI-RS beam set corresponding to the SS beam for transmission of the CSI-RS. Thus, in the present disclosure, the target gNB may use a portion of CSI-RS transmission resources included in the CSI-RS configuration information in order to transmit a CSI-RS beam set corresponding to the RAP reception SS beam.

8. The target gNB transmits the CSI-RS through a plurality of narrow beams corresponding to the wide beam for receiving RAP in operation S4190.

Here, the CSI-RS may be transmitted using only a portion of the CSI-RS transmission resources specified in the CSI-RS configuration, as indicated to the UE in the RAR.

The ue measures signal strength or quality of CSI-RS transmitted by the target gNB based on CSI-RS subset information 4101 included in the RAR and CSI-RS configuration information transmitted with the handover command.

10. The UE having uplink synchronization receives the RAR and transmits a handover confirm to the target gNB through UL grant included in the RAR in operation S4191.

A. When transmitting the handover acknowledgement, the UE also transmits feedback 4102 for measurement results of CSI-RS. At this time, the UE uses UL grant included in the RAR.

11. Based on the CSI-RS feedback of the UE, the target gNB selects a narrow beam to be used by the UE and informs the UE in operation S4192.

Next, the operation of the present disclosure will be described in the case where an idle mode UE initially accesses the gNB. The initial access operation is as follows.

[ initial Access ]

Fig. 42 is a flowchart illustrating a random access operation according to an embodiment of the present disclosure.

Referring to fig. 42, an initial access operation will be described.

1. In performing a Receive (RX) beam scan, the UE measures the signal strength or quality of each beam of the SS transmitted by the gNB through the TX beam scan.

2. When measuring the SS, the UE transmits RAP to one or more gNB beams having the maximum signal strength in operation S4210.

3. When the RAP is received, the gNB transmits the RAR to the UE by using one or more gNB beams having the maximum signal strength in operation S4220.

The rar contains UL grant so that the UE can send RRC connection request.

4. After receiving the RAR, the UE transmits an RRC connection request to the gNB through UL grant included in the RAR in operation S4230.

5. After receiving the RRC connection request from the UE, the gNB transmits RRC connection establishment to the UE in operation S4240.

6. After receiving the RRC connection setup from the gNB, the UE transmits an RRC connection setup complete to the gNB in operation S4250.

A. By doing so, the UE completes initial access to the gNB.

Since the above operation is the same as the initial access operation defined in LTE, a detailed description of each message is omitted. This initial access operation is designed for the case where the gNB uses only one RS. This is not applicable to the case considered in the present disclosure, that is, the case where determining whether to perform initial access is based on an SS transmitted on a wide beam, but actual data transmission/reception uses a narrow beam. The inapplicability is because the UE cannot determine a narrow beam to be used for transmitting and receiving data to and from the gNB despite the completion of the initial access.

In the present disclosure, a UE determines whether to perform initial access by measuring an SS transmitted on a wide beam and then performs measurement of CSI-RS transmitted on a narrow beam during an initial access procedure in order to find a narrow beam to be used with a gNB as soon as possible. Hereinafter, various embodiments will be described.

Fig. 43-47 are flowcharts illustrating various methods for determining beams to be used for data transmission and reception in a random access procedure according to various embodiments of the present disclosure.

Initial access: proposal 1]

With reference to fig. 43, the [ initial access: the embodiment of proposal 1.

1. In performing RX beam scanning, the UE measures the signal strength or quality of each beam of the SS transmitted by the gNB through TX beam scanning.

2. When measuring the SS, the UE transmits RAP to one or more gNB beams having the maximum signal strength in operation S4310.

3. When the RAP is received, the gNB transmits the RAR to the UE by using one or more gNB beams having the maximum signal strength in operation S4320.

The rar contains UL grant so that the UE can send RRC connection request.

B. In addition, in the present disclosure, CSI-RS configuration information 4300 is transmitted to the UE along with the RAR. Details of the CSI-RS configuration information are described above.

The gNB transmits the CSI-RS through a plurality of narrow beams corresponding to a wide beam for receiving the RAP or a beam having the maximum signal strength among the wide beams for receiving the RAP in operation S4330.

5. Based on the CSI-RS configuration information, the UE measures signal strength or quality of CSI-RS transmitted by the gNB.

6. After receiving the RAR, the UE transmits an RRC connection request to the gNB through UL grant included in the RAR in operation S4340.

A. When sending the RRC connection request, the UE also sends feedback 4301 of CSI-RS measurements.

7. After receiving the RRC connection request from the UE, the gNB transmits RRC connection establishment to the UE in operation S4350.

Here, the RRC connection establishment may be transmitted using a beam having the greatest signal strength among a narrow beam included in the CSI-RS feedback and a wide beam for transmitting the RAR.

8. After receiving the RRC connection setup from the gNB, the UE transmits an RRC connection setup complete to the gNB in operation S4360.

A. By doing so, the UE completes initial access to the gNB.

Initial access: proposal 2]

With reference to fig. 44, a description will be given of [ initial access: the embodiment of proposal 2.

2. When measuring the SS, the UE transmits RAP to one or more gNB beams having the maximum signal strength in operation S4410.

3. When the RAP is received, the gNB transmits the RAR to the UE by using one or more gNB beams having the maximum signal strength in operation S4420.

The rar contains UL grant so that the UE can send RRC connection request.

B. In addition, in the present disclosure, CSI-RS configuration information 4400 is transmitted to the UE along with the RAR. Details of the CSI-RS configuration information are described above.

The gnb transmits the CSI-RS through a plurality of narrow beams corresponding to a wide beam for receiving RAPs or a beam having the maximum signal strength among the wide beams for receiving RAPs in operation S4430.

6. After receiving the RAR, the UE transmits an RRC connection request to the gNB through UL grant included in the RAR in operation S4440.

7. After receiving the RRC connection request from the UE, the gNB transmits RRC connection establishment to the UE in operation S4450.

8. After receiving the RRC connection setup from the gNB, the UE transmits an RRC connection setup complete to the gNB in operation S4460.

A. When the transmission RRC connection establishment is completed, the UE also transmits feedback 4401 of CSI-RS measurement results.

B. By doing so, the UE completes initial access to the gNB.

Initial access: proposal 3]

With reference to fig. 45, the [ initial access: the embodiment of proposal 3 ].

2. When measuring the SS, the UE transmits RAP to one or more gNB beams having the maximum signal strength in operation S4510.

3. When the RAP is received, the gNB transmits the RAR to the UE by using one or more gNB beams having the maximum signal strength in operation S4520.

The rar contains UL grant so that the UE can send RRC connection request.

B. In addition, in the present disclosure, CSI-RS configuration information 4500 is transmitted to the UE together with the RAR. Details of the CSI-RS configuration information are described above.

The gNB transmits the CSI-RS through a plurality of narrow beams corresponding to a wide beam for receiving the RAP or a beam having the maximum signal strength among the wide beams for receiving the RAP in operation S4530.

6. After receiving the RAR, the UE transmits an RRC connection request to the gNB through UL grant included in the RAR in operation S4540.

7. After receiving the RRC connection request from the UE, the gNB transmits RRC connection establishment to the UE in operation S4550.

8. After receiving the RRC connection setup from the gNB, the UE transmits an RRC connection setup complete to the gNB in operation S4560.

A. By doing so, the UE completes initial access to the gNB.

The gNB allocates UL grant for receiving CSI-RS feedback to the UE, and the UE transmits feedback of CSI-RS measurement results to the gNB through the allocated UL grant in operation S4570.

Initial access: proposal 4]

With reference to fig. 46, the [ initial access: the embodiment of proposal 4 ].

2. When measuring the SS, the UE transmits RAP to one or more gNB beams having the maximum signal strength in operation S4610.

3. When the RAP is received, the gNB transmits the RAR to the UE by using one or more gNB beams having the maximum signal strength in operation S4620.

The rar contains UL grant so that the UE can send RRC connection request.

4. After receiving the RAR, the UE transmits an RRC connection request to the gNB through UL grant included in the RAR in operation S4630.

5. After receiving the RRC connection request from the UE, the gNB transmits RRC connection establishment to the UE in operation S4640.

A. In addition, in the present disclosure, CSI-RS configuration information 4600 is transmitted to the UE along with the RAR. Details of the CSI-RS configuration information are described above.

The gnb transmits the CSI-RS through a plurality of narrow beams corresponding to a wide beam for receiving RAPs or a beam having the maximum signal strength among the wide beams for receiving RAPs in operation S4650.

7. Based on the CSI-RS configuration information, the UE measures signal strength or quality of CSI-RS transmitted by the gNB.

8. After receiving the RRC connection setup from the gNB, the UE transmits an RRC connection setup complete to the gNB in operation S4660.

A. When the transmission RRC connection establishment is completed, the UE also transmits feedback 4601 of CSI-RS measurement results.

B. By doing so, the UE completes initial access to the gNB.

Initial access: proposal 5]

With reference to fig. 47, the [ initial access: the embodiment of proposal 5.

2. When measuring the SS, the UE transmits RAP to one or more gNB beams having the maximum signal strength in operation S4710.

3. When the RAP is received, the gNB transmits the RAR to the UE by using one or more gNB beams having the maximum signal strength in operation S4720.

The rar contains UL grant so that the UE can send RRC connection request.

4. After receiving the RAR, the UE transmits an RRC connection request to the gNB through UL grant included in the RAR in operation S4730.

5. After receiving the RRC connection request from the UE, the gNB transmits RRC connection establishment to the UE in operation S4740.

A. In addition, in the present disclosure, CSI-RS configuration information 4700 is transmitted to the UE along with the RAR. Details of the CSI-RS configuration information are described above.

The gnb transmits the CSI-RS through a plurality of narrow beams corresponding to a wide beam for receiving RAPs or a beam having the maximum signal strength among the wide beams for receiving RAPs in operation S4750.

8. After receiving the RRC connection setup from the gNB, the UE transmits an RRC connection setup complete to the gNB in operation S4760.

A. By doing so, the UE completes initial access to the gNB.

The gNB allocates UL grant for receiving CSI-RS feedback to the UE, and the UE transmits feedback 4701 of CSI-RS measurement results to the gNB through the allocated UL grant in operation S4770.

< fourth embodiment >

In the LTE system, in order to support broadband, a multi-carrier scheme such as carrier aggregation (carrier aggregation, CA) and dual connectivity (dual connectivity, DC) for processing a plurality of component carriers (component carrier, CC) together has been introduced. In the case of 20MHz CCs, aggregation of up to 32 CCs may support 640MHz bandwidth. However, if a scheme such as LTE CA is applied to support ultra wideband (e.g., 1 GHz) in a 5G New Radio (NR) system, the number of combinations of CCs to be used by a terminal grows exponentially, and the size of capability reports performed by the terminal also increases. Therefore, the terminal has no choice but to operate only within a limited CC combination. In addition, as the number of CCs in CA increases, the reception complexity of the terminal and the control complexity of the base station also increase. However, although CA or DC has such a problem, CA or DC has greater flexibility in using resources than a single carrier. This is because secondary (SCell) addition/release allows changing the extension band and cross-carrier scheduling allows scheduling resource transmission/reception of other CCs.

In addition, 5G systems define efficient operation, the main goal of which is to increase the power efficiency of the terminal and base station network by more than 1000 times. For this reason, it is necessary to control the size of the operation band of the terminal in order to solve the possibility of additional power consumption caused by broadband transmission, which is essential for the operation of ultra high frequency band (mmW).

The present disclosure proposes an operation scheme of a terminal and a base station for implementing the energy efficiency key performance indicators (key performance indicator, KPI) in question in 3gpp RAN 5g system information (system information, SI). In particular, the present disclosure relates to layer 1/2 operation of terminals and base stations in a mobile communication system. More particularly, the present disclosure relates to a method and apparatus for changing an operating band of a terminal to reduce power consumption of the terminal when a base station desires ultra-wideband signal transmission/reception with the terminal.

The present disclosure proposes a control and setting method for ultra wideband transmission/reception in a 5G mobile communication system. In particular, methods for scheduling, handover and power saving in ultra wideband are considered. In a 5G mobile communication system, it is desirable to support various services (or slices) such as enhanced mobile broadband (enhanced mobile broadband, eMBB), ultra-reliable and low-latency communication (ultra reliable and low latency communication, URLLC), and enhanced machine type communication (enhanced machine type communication, eMTC). This can BE understood in the same context as supporting voice over internet protocol (voice over Internet protocol, voIP) and Best Effort (BE) services in LTE, which is a fourth generation (4G) mobile communication system. Further, it is expected that various numerologies (numerology) will be supported in the 5G mobile communication system. In particular due to differences in subcarrier spacing or Transmission Time Intervals (TTI). Accordingly, it is desirable to support TTIs of various lengths in a 5G mobile communication system. This is one of the significant features of the 5G mobile communication system, compared to LTE, which supports only one TTI (1 ms). If the 5G mobile communication system supports a TTI much shorter than the 1ms TTI of LTE (e.g. 0.1 ms), this is expected to be a great help to support URLLC requiring short delay times. In this disclosure, numerology is used as a term having the same meaning as subcarrier spacing, subframe length, symbol/sequence length, and the like. Moreover, the terminals may be configured with different Bandwidths (BW) in different digital areas. A base station may also be referred to by various terms such as gNB, eNB, NB and BS. A terminal may also be referred to as various terms such as UE, MS, and STA.

Fig. 48 is a diagram illustrating an LTE scalable BW system according to an embodiment of the present disclosure.

Fig. 49 is a diagram illustrating features of a 5G NR flexible BW system according to an embodiment of the present disclosure.

Referring to fig. 48, LTE has introduced the concept of scalable BW in order to support various BW. According to fig. 48, the lte system supports terminals having various BW (e.g., 5/10/20 MHz) with the same center frequency. For example, if the first UE 4810 supports 5MHz and the second UE 4810 supports 10MHz, the LTE base station appropriately configures the control channel and transmits the control signal so that both UEs can receive the control signal. However, when the total available bandwidth of the base station is very large, i.e. in ultra wideband, this approach greatly limits the resources that can be used by terminals with relatively small frequency bands. For example, when the third UE 4830 operates at the edge of the base station's available frequency band, the UE 4830 may not receive the control signal of the base station differently.

Referring to fig. 49, in the 5G NR communication system, an operation band should be flexibly configured. That is, after successfully establishing an RRC connection by the access BW 4900 configured according to the synchronization signal reception and the SI acquisition, the terminal may switch an operation band (or operation BW) from a relatively narrow band (or narrow BW) 4910 to a relatively wide band (or wide BW) 4920 under the control of the base station. Using a wide frequency band, a terminal may receive a control signal of a base station to help improve control signal performance, or may perform data transmission/reception (DL or UL) to improve resource efficiency.

Also, in the 5G NR communication system, the terminal should be able to transmit and receive important control signals in order to maintain connection with the base station even in a certain frequency band that is not supported by the existing scalable BW system. In the case of LTE, such important control signals are sent via the PCell by means of signaling radio bearers (signaling radio bearer, SRBs). Further, in the PCell, control signals for scheduling and hybrid automatic repeat request (HARQ) processes in the PCell itself and the SCell are transmitted and received. In LTE, each of the PCell or SCell may be a separate cell. For each cell, a separate MAC entity and corresponding link adaptation and HARQ entity are required. However, in the 5G NR single carrier communication system, the entire frequency band corresponds to one cell. In addition, basically functions of the PCell for terminal access, connection establishment/maintenance, and data transmission/reception should be provided.

Meanwhile, even though the base station operates in ultra wideband, the terminal may perform transmission/reception only in a portion of the entire frequency band due to limited implementation and complexity. In order for a terminal to operate in a frequency band greater than the maximum available bandwidth (i.e., the allowable BW), it is necessary to operate in a time division manner. For easier management, the base station may divide ultra wideband into frequency bands or sub-bands (sub-bands) having an appropriate size and instruct the terminal to perform various functions (e.g., control signal transmission/reception, data signal transmission/reception, RS, measurement, scheduling, link adaptation, modulation Coding Scheme (MCS), HARQ, etc.) in a specific frequency band. Also, the terminal may determine and receive the structure of the control channel and the reference signal based on the frequency band.

Fig. 50 is a diagram illustrating various band division schemes in a 5G NR flexible BW system according to an embodiment of the present disclosure.

Referring to fig. 50, in case a, due to the fixed band configuration, UE1 5000 may operate in only a portion of the available frequency band, not the entire available frequency band.

In case B, UE2 5010 may not be supported in band 4 because the maximum available bandwidth is less than the bandwidth 5011 of band 4 configured by the base station.

If the band unit is minimized as in case C, the UE 5020 having various bandwidths can be supported because the band to be used by the UE is represented by a bundle of small bands. However, too many bands may cause an increase in overhead.

Therefore, as in case D, a scheme of freely configuring the band size is useful.

In order to solve the above-described problem when a base station divides an entire frequency band into frequency bands of terminals, the present disclosure considers a scheme in which the base station configures different-sized frequency bands for the respective terminals, and a system can represent the frequency bands as a combination of sub-bands having the same size. Also, instead of performing independent scheduling, link adaptation, MCS and HARQ processes in sub-bands divided in view of the system, one scheduling, link adaptation, MCS and HARQ process will be performed in a frequency band configured in view of the terminal.

The structure of the physical layer control channel should be designed to be scalable in one frequency band into one or more subbands. This means that terminals having a frequency band that can be represented by a multiple of at least a sub-band in the frequency band can be supported. The size of the frequency band as a bundle of subbands is determined by at least one of channel characteristics, numerology, control subband size, and minimum packet size between the terminal and the base station. The terminal performs one MAC function set (scheduling, MCS, HARQ, etc.) for one service.

The functions that may be provided by the system architecture presented in this disclosure may be considered as follows.

Configuration of control/RS/CSI reporting/HARQ feedback per band

Self-band/cross-band scheduling

Band aggregation for transmitting individual transport blocks

Trans-band HARQ retransmission

-RRM measurement

Power saving with adaptive BW

Configuration of control/RS/CSI reporting/HARQ feedback per band

When configuring a frequency band, a base station may inform a terminal of the range (i.e., start, size or center frequency, and bandwidth) of the frequency band by representing a multiple of a basic unit (RB or sub-band). Because the location and range of the frequency band are part of one carrier in which the network system operates, the base station can configure the frequency band for the terminal through the frequency offset and bandwidth of the center frequency of the entire carrier frequency band. Alternatively, the base station may configure the frequency band for the terminal by a frequency offset and a bandwidth of a center frequency where the synchronization signal detected by the terminal is located. Meanwhile, the center frequency of the carrier band learned by the terminal may always be the center frequency of the synchronization signal detected by the terminal, may be the same as the center frequency information of the carrier indicated by the SI connected to the synchronization signal detected by the terminal, or may be the same as the center frequency information of the carrier indicated by the base station in the RRC connection establishment procedure. The terminal interprets the frequency band range as a system frequency band. Therefore, even though frequency bands of different ranges are allocated, the terminal should be designed to receive signals according to the same reception rule.

For example, the location of a Reference Signal (RS) or a control channel transmitted by a base station should be determined based on the start and size of a frequency band configured for a terminal. Further, the position of the CSI report or HARQ feedback transmitted by the terminal should be determined based on the start and size of the frequency band configured for the terminal. Meanwhile, when configuring a plurality of frequency bands, the base station may also configure for the terminal whether to share the HARQ process for the plurality of frequency bands or separate the HARQ process for each frequency band.

The frequency band configured for terminal monitoring is called primary band (p-band). The terminal may not perform monitoring in a resource region other than the p-band unless there is any control/configuration separate from the p-band.

A secondary band (s-band) may be selectively operated according to a configuration through the p-band, and the p-band and the s-band may be referred to as a first Radio Frequency (RF) band and a second RF band, respectively. Further, the p-band may be activated to an active state from at least one or more configured band candidates through an RRC message or MAC CE or DCI. Further, s-band may be activated to an active state from at least one or more configured band candidates through an RRC message or MAC CE or DCI. Similarly, the base station may deactivate one or more frequency bands from an active state to an inactive state by sending a deactivation signal or message to the terminal via an RRC message or MAC CE or DCI. In the present disclosure, the active band and the p band are used as similar meanings, but the p band requires a combination of DL band and UL band at the time of configuration. Thus, the p-band is an active band, but all active bands are not always p-bands. Furthermore, the p-band is not disabled except for a separate band switching procedure. In the case of Time Division Duplexing (TDD), the frequency locations of the DL and UL bands may be the same in the p-band.

The p-band configuration includes at least one DL band and one or more UL bands, and the base station may instruct the terminal to configure the p-band. When the terminal reports the UE capability report including RF information to the base station, the base station may configure a p-band for each different RF of the terminal.

In the following, the operations associated with the band switch/activation indication in a single or multiple active bands will be described.

The terminal may monitor one or more configured frequency bands simultaneously according to RF conditions. Therefore, it is advantageous in terms of scalability that the band indication of the base station is commonly applied to the terminal under different RF conditions. However, the base station needs to know other RF conditions of the terminal in advance through the capability report of the terminal. Otherwise, when an activation instruction from the band #1 to the band #2 is issued for a certain terminal, there is a possibility of erroneous operation because it is impossible to know whether the band #1 is deactivated due to the RF limitation of the terminal.

When a terminal operating in a single active frequency band receives a frequency band activation indication from a base station, the terminal switches to the indicated frequency band and deactivates the previous frequency band. When a terminal operating in a plurality of active frequency bands receives a frequency band activation instruction from a base station, the terminal activates the indicated frequency band and maintains the use of the frequency band.

However, the band configuration by the capability report of the terminal may possibly be erroneously operated. Thus, the base station should be able to configure the maximum number of active bands of the terminal and clearly indicate the deactivation of the bands.

The activation/deactivation operation rules for the frequency bands may be preconfigured according to one of the following two methods or may be configured by the base station/network. Furthermore, the operation can be equally applied to the case where the band switch/activation occurs together with the cross-band scheduling indication, in addition to the individual band activation indication of the base station.

a) Although a plurality of active frequency bands are configured, each active frequency band can be switched to only the other inactive frequency band. Thus, the number of active bands can be changed only with RRC.

b) A plurality of active frequency bands are configured and an activation/deactivation indication is made for each frequency band. Because the number of active frequency bands can be changed, the base station should be operated so as not to exceed the maximum number of active frequency bands of the terminal and to deactivate all frequency bands. If the base station indicates that the maximum active frequency band is exceeded, the terminal may operate in the previous active frequency band to 1) deactivate the initially activated frequency band, 2) deactivate the last activated frequency band, 3) deactivate the frequency band that is lowest in order of frequency band index, 4) deactivate the lowest frequency band according to the priority of the frequency band configured by the base station, or 5) deactivate a certain frequency band arbitrarily determined by the terminal. Moreover, the deactivated frequency band may be configured to exclude the p-band.

Hereinafter, a procedure for determining a mobile point including a retuning (retuning) delay when a band is activated through DCI or MAC CE will be described.

The RF retune time may vary according to the relationship between the handover band and the active band handover condition of the terminal. The base station may configure the terminal with the time required to switch one frequency band (e.g., p-band) to another frequency band through RRC based on the capability report of the terminal. If the terminal does not conform to the configuration, the terminal may reject the band switch for each band.

In case that the base station indicates band switching through DCI, 1) the terminal may consider a switching delay time from a DCI reception time (subframe/slot/mini-slot) that has been configured through RRC to when the switching is completed. Accordingly, the terminal may monitor a control channel from the fastest effective control channel in a frequency band activated after a switching delay time from a DCI reception time based on a frequency band Identification (ID) included in the DCI. Alternatively, 2) a handover delay time k from a DCI reception time (subframe/slot/mini-slot) to a time when handover is completed and a band ID may be included in the DCI. Thus, the terminal can monitor the control channel from the fastest valid control channel after a time determined according to the value of k.

In case that the base station indicates a band handover through the MAC CE, 1) the terminal may monitor a control channel from the fastest effective control channel in a band activated after a handover delay time from a HARQ ACK success time (subframe/slot/mini slot) for reception of the MAC CE to a time of completion of the handover by considering a handover time having passed through the RRC configuration based on a band ID included in the MAC CE. Alternatively, 2) the terminal may consider a handover delay time that has been configured through RRC. The terminal may monitor the control channel from the fastest effective control channel in the frequency band activated after a switching delay time from a time (subframe/slot/mini-slot) when the MAC determines a frequency band switch and transmits an indication to the PHY to a time when the switch is completed, based on the frequency band ID included in the MAC CE. Alternatively, 3) a handover delay time k from the reception success time (subframe/slot/mini-slot) of the MAC CE to the time of handover completion and a band ID may be included in the MAC CE. Thus, the terminal can monitor the control channel from the fastest effective control channel in the frequency band activated after the switching delay time from the reception success time (subframe/slot/mini-slot) of the MAC CE to the completion of the switching. Alternatively, 4) a handover delay time k from a transmission time (subframe/slot/mini-slot) for the MAC CE to receive a successful HARQ ACK to a time when the handover is completed, and a band ID may be included in the MAC CE. Accordingly, the terminal can monitor the control channel from the fastest effective control channel in the frequency band activated after a switching delay time from a transmission time (subframe/slot/mini-slot) for the MAC CE to receive a successful HARQ ACK to when the switching is completed. The terminal follows at least one of the operations described above.

Self-band/cross-band scheduling

Fig. 51 is a diagram illustrating a self-band/cross-band scheduling operation according to an embodiment of the present disclosure.

Referring to fig. 51, a base station may schedule a data channel 5120 in the same sub-band, a data channel 5140 in other sub-bands, or a control channel 5160 in other sub-bands through control sub-bands 5110, 5130, and 5150 in the p-band.

The base station may control transmission/reception of signals through a control channel or a data channel of the terminal through a control subband within a p-band configured for each terminal. The base station may indicate a Downlink (DL) or Uplink (UL) data transmission/reception region through a self-band data schedule or a cross-band data schedule. Also, the base station may indicate a change in the position or size of the control subband in the same frequency band through the self-band control scheduling. Also, the base station may indicate the location or size of additional control subbands in other bands through cross-band control scheduling.

If the position or size of the second control sub-band is indicated by the first control sub-band, the terminal checks whether to monitor the first control sub-band and the second control sub-band at the same time. If so, the terminal may receive signals through both control subbands simultaneously. Otherwise, this means that the terminal monitors only the first control subband. Thus, to monitor the second control subband, a delay for a certain amount of RF retuning is required.

In general, in the case of UL scheduling, the base station may instruct the terminal to a predetermined delay value (e.g., 4 ms) or a separate delay value through a control subband.

In the system considered in the present disclosure, cross-band scheduling in which a bandwidth change may be required, even in the case of DL scheduling, a specific subframe immediately following in time needs to be separately indicated, and a Physical Downlink Shared Channel (PDSCH) for data transmission/reception is normally indicated in the same subframe as the PDCCH.

This is because processing time for retuning the RF and baseband (BB) circuits is required when the position of the used frequency band changes suddenly. That is, the base station should instruct the terminal to transmit and receive DL signals after a delay time configured after transmission of the control signal, taking into consideration available frequency band information included in the terminal capability report and the degree of variation of the usage frequency band of the terminal caused by control of the base station. The delay time may be included in each control signal, or the base station may pre-configure at least one delay time value during a capability negotiation and connection establishment procedure of the terminal. Since the delay is larger in the case where the usage frequency band of the terminal is completely changed than in the case where the usage frequency band of the terminal is partially overlapped and only the bandwidth is changed, the base station transmits a delay time by each control signal or an index of two or more delay values by the control signal so that the terminal can perform a DL reception operation after an appropriate delay.

Meanwhile, the base station may perform asymmetric p-band configuration in which the terminal has different frequency bands (positions, sizes) in DL and UL. However, since the main control function operates smoothly in the p-band when both DL and UL are supported, the terminal understands the p-band as one even though different bands are allocated.

[ adaptive BW method and Power saving procedure ]

The LTE system provides a Power Save Mode (PSM) and Discontinuous Reception (DRX) to reduce power consumption. PSM refers to a state in which only a tracking area update (tracking area update, TAU) or a routing area update (routing area update, RAU) is performed and no page is received from the base station. This is almost similar to a power outage, but the terminal does not need to re-attach to the network or re-establish a packet data network (packet datanetwork, PDN) connection, as it is still registered in the network.

DRX is classified into idle mode DRX and connected mode DRX. According to the idle mode DRX (i.e., idle-DRX), the idle mode UE does not receive signals of the base station except for a period (paging frame number and paging occasion) for periodically monitoring the paging signal. In this case, the network does not have context information of the terminal because the terminal does not have an RRC connection with the network. The terminal is considered to be registered in a mobility management entity (mobility management entity, MME) and camped within a tracking area list (tracking area list, TAL). The purpose of the connected mode DRX is to reduce power consumption caused when a connected mode terminal monitors a control signal (PDCCH) of a base station per DL subframe. If the terminal skips monitoring of DL subframes arbitrarily, it is difficult for the base station to control the terminal as needed. Therefore, the base station and the terminal should perform transmission of the base station and reception of the terminal in DL subframes of a predetermined position.

The DRX operation of the LTE connection is as follows. The base station may configure DRX related parameters among RRC parameters through an RRC connection setup request message or an RRC connection reestablishment request message. DRX related parameters include, for example, DRX cycle (cycle), on-duration timer (ON-duration timer), and inactivity timer (inactivity timer). The DRX cycle indicates the length of a single duration in which the terminal repeats ON and OFF, and the ON duration timer indicates the length of the ON duration. The length of the off duration may be calculated from the DRX cycle and the on duration timer. These parameters are expressed in units of subframes. The terminal monitors DL signals on the PDCCH of the base station during the on-duration indicated by the on-duration timer and does not monitor DL signals on the PDCCH of the base station during the off-duration. The inactivity timer starts from a certain subframe if the terminal successfully receives a DL signal in that subframe. The terminal should monitor DL signals on the PDCCH of the base station until the inactivity timer expires. After the last successful reception of the DL signal, the terminal does not monitor the DL signal if a subframe corresponding to the expiration time of the inactivity timer is reached and belongs to the off duration.

In particular, depending on the DRX cycle, C-DRX may be classified into short DRX and long DRX. Depending on the activity of the DL signal, the terminal always switches to short DRX in each subframe, then to long DRX, and again switches to a state of no DRX operation when the long DRX cycle ends. To configure this operation, a short DRX cycle timer is used to indicate the number of repetitions of the short DRX cycle. In the case of long DRX, the terminal switches to a sleep state after one long DRX cycle. The base station may instruct the start of short DRX or long DRX through a MAC Command Element (CE) so that the terminal switches back to short DRX or maintains a long DRX state. In addition, in DL HARQ packet retransmission defined as HARQ Round Trip Time (RTT), the terminal should monitor DL signals regardless of DRX. Furthermore, if UL HARQ packet retransmission is desired, the terminal should monitor DL control signals, i.e., UL grants, for a duration configured as a DRX retransmission timer.

According to LTE, short DRX is expressed as follows:

[ (SFN x 10) +subframe number ] module (short drx-Cycle) = (drxStartOffset) module (short drx-Cycle)

According to LTE, long DRX is expressed as follows:

[ (SFN x 10) +subframe number ] module (longDRX-Cycle) =drxstartoffset

Similar equations can be used when LTE connected mode DRX (C-DRX) is applied to 5G NR.

If LTE C-DRX is applied to 5G NR, a terminal receiving high speed data service will monitor a wideband DL signal of a base station for an on duration and will not monitor the DL signal for an off duration. However, depending on the characteristics of the traffic, it is not necessary to receive a wideband DL signal every subframe. For example, in the case of streaming service, an encoding scheme for transmitting only image change information in periodic large-capacity information is used. Therefore, in the 5G NR communication system, the size of Bandwidth (BW) of resources monitored by the terminal should be adaptively changed.

Fig. 52 to 54 are diagrams illustrating an example of BW expansion and reduction operations by a physical layer control signal according to various embodiments of the present disclosure.

If this variable BW control is performed on the L1 layer (i.e., physical layer), the operations as shown in fig. 52 to 55 are possible. To save power it is reasonable that the terminal is basically in a narrow BW state and switches to a wide BW if needed.

Referring to fig. 52, therefore, the terminal monitors a narrowband control sub-band (CSB) (csb#1) 5210 provided by L1 in an RRC connection setup step, and monitors a wideband control sub-band (csb#2) 5220 in a specific subframe if an L1 signal 5230 indicating BW extension is received from the base station.

An interval between a time point at which the BW expansion instruction control signal is received and a subframe in which the handover to csb#2 is performed is determined according to at least one of: a) fixed interval, b) interval configured by RRC parameters, c) interval configured by L1 control signals, d) interval computable according to BW capability information reported by the terminal and current terminal state, and e) whether the center frequencies of BW to be switched overlap.

On the other hand, when the terminal continuously requests a large amount of traffic, the BW expansion instruction control signal should be frequently transmitted, and in the worst case, half of the subframes may be served in the narrowband due to the limitation of the handover delay. Furthermore, frequent BW and RF switching may result in end loads and additional power consumption.

Referring to fig. 53, an example is shown in which the BW reduction instruction control signal is further used to solve the problem when only the BW extension instruction control signal is used.

According to this operation, the terminal monitors cbs#1 5310, switches the bandwidth to monitor csb#2 5320 when receiving BW extension instruction control signal 5330, and maintains the mode. Then, when receiving the BW reduction instruction control signal 5360 through csb#2 5340, the terminal switches the bandwidth to monitor csb#1 5350. However, if the BW expansion or contraction instruction control signal is not received, the method may cause an error in the operation of the terminal.

For example, although the base station transmits the BW-spreading instruction control signal 5330 and transmits a control signal (DCI) for data transmission/reception through csb#2 5320 indicating a subframe, the terminal may not receive the BW-spreading instruction control signal 5330. Since csb#1 is being monitored, the terminal does not receive DCI transmitted through csb#2 5320. In this case, even if the terminal successfully receives the BW extension indication control signal 5330 or the terminal fails to receive the BW extension indication control signal 5330, the base station does not know whether the terminal fails to receive the DCI transmitted through the csb#2 5320.

Also, if the terminal fails to receive the DL signal within a certain time due to mismatch of the monitoring band (i.e., CSB), the terminal may operate as DRX off or cause a problem in the HARQ timeline.

According to the operations shown in fig. 54 and 55, the problem of the L1 signal reception error can be reduced by not using the BW reduction instruction control signal. That is, the terminal may operate in the wideband (csb#2) only during a specific duration after BW extension and then return to the narrowband (csb#1).

Referring to fig. 54, the base station also notifies the terminal of a duration 5440 for monitoring csb#2 and csb#2 position 5420 through BW extension instruction control signal 5430 in cbs#1 5410.

On the other hand, considering capacity and performance of the L1 signal, the base station may configure duration information for maintaining the broadband in advance through RRC parameters instead of the L1 signal. However, compared to the case of using the L1 signal, dynamic control may be restricted in the case of configuring in advance through RRC. Thus, when using RRC parameters, a timer may be useful, such as an existing DRX inactivity timer, rather than a fixed duration.

Fig. 55 to 58 are diagrams illustrating an example of BW expansion and reduction operations by a physical layer and a Radio Resource Control (RRC) control signal according to various embodiments of the present disclosure.

Referring to fig. 55, the terminal monitors csb#2 indicated by the BW extension instruction control signal 5530 in cbs#1 5510 and then starts an RRC configured timer 5540 due to failure to receive a DL signal from a next csb#2 5520 subframe. If the timer expires after 3 subframes without receiving a DL signal, the terminal returns to narrowband csb#1 in the next subframe. The start time of the timer may be changed.

If the timer value is set small, the terminal may not continuously receive the base station signal due to degradation of the channel quality even though the control signal of the base station is actually transmitted to the terminal. In this case, a band mismatch may occur in which the base station transmits a signal in a wideband and the terminal tries to receive a signal in a narrowband. The base station may start a timer from when feedback of the terminal or a scheduled UL signal does not arrive or when an event that no UL signal arrives satisfies a given condition. When the base station's timer expires, the base station transmits a base station signal over a narrowband control channel (i.e., csb#1). To support this operation, the location of the on duration of the narrowband control channel of the terminal may be predetermined. That is, the start of operation in the wideband may depend on the L1/MAC signal, and the control channel reception operation in the narrowband may follow a DRX cycle determined based on the system time, such as a conventional DRX operation. When the wideband inactivity timer expires according to inactivity of the control channel in the wideband, the terminal retunes to the narrowband and receives the control channel according to the configured DRX on duration.

On the other hand, the interpretation of inactivity may be applied differently, as the case may be.

Referring to fig. 56, the terminal switches to the wideband 5610 in response to the BW extension indication control signal 5620, and then receives the BW reduction indication control signal 5630 of the base station in the next subframe. This is because the base station has determined that there is no more traffic to send over broadband.

The inactivity timer 5650 of the RRC configuration may be maintained without expiring even though the terminal monitors the narrowband csb#1. That is, in a state in which the terminal does not receive the DL resource allocation control signal in the wideband (i.e., csb#2), the terminal operation of switching between the wideband and the narrowband in response to the control signal of the base station or a certain rule may affect the inactivity timer. The terminal may stop the timer only after receiving the DL resource allocation control signal through csb#2 in the broadband.

Shown with reference to fig. 57 is an operation in which after the timer 5710 is started, the timer expires when a base station signal is successfully received through the wideband csb#25730 during BW handover of the terminal, and the second timer 5720 is started when a DL signal is not received in a subsequent subframe.

Referring to fig. 58, in order to avoid the complicated operations as shown in fig. 56 and 57, according to an embodiment, a base station may configure a mode 5810 for switching between wideband and narrowband through RRC after wideband switching of a terminal. As in other embodiments, the base station may instruct the terminal to perform the first narrowband handoff via an L1 control signal 5820 or an RRC signal. When RRC control is used, the location should be determined based on SFN (system frame number ) and subframes. If the BW handoff is not urgent, the L1 control signal may be replaced with a MAC Command Element (CE). In this case, the MAC CE should include absolute location information instead of relative interval information.

The mode of BW switching may be configured as an absolute position with respect to the SFN and the subframe, or as a position with respect to a position specified with the L1 control signal. Further, the mode valid subframes may be limited to subframes corresponding to the DRX on duration or subframes before the DRX cycle timer expires. Further, through MAC CE, the base station can instruct the terminal to which BW to switch.

When the base station indicates BW switching operation using a physical layer signal or an RRC control signal, setting by an L1 control signal may be prioritized over setting by an RRC control signal for dynamic setting. However, considering the case where it is difficult to perform stable terminal operation due to a plurality of L1 control signals, setting by the RRC control signal in a subframe having a predetermined position (period, offset) is always before setting by the L1 control signal.

Meanwhile, the C-DRX of LTE, i.e., connected DRX operation, may be modified to be associated with BW control, independently of BW control operation by a physical layer signal. The method using the C-DRX may be operated alone or may be operated together with an operation of controlling BW through a physical layer signal. Specific details are described below with reference to fig. 59.

Fig. 59 and 60 are diagrams illustrating examples of connected mode DRX (C-DRX) operation for adaptive BW according to various embodiments of the present disclosure.

According to the LTE DRX configuration, one DRX cycle is divided into an on duration and an off duration. Similarly, referring to fig. 59, the base station may divide one DRX cycle into a wideband on duration 5910, a narrowband on duration 5920, and an off duration 5930. For this scheme, the base station only needs to inform the terminal of additional on-duration information for each frequency band in the DRX configuration information. However, if there are various gradually decreasing band sizes, the terminal may take a considerable time to transition to the fully-off state.

Referring to fig. 60, according to another embodiment, a terminal may operate in a band-specific DRX cycle, wherein the duration for monitoring the wideband and narrowband may be configured differently in time. This is similar to operation in LTE C-DRX that switches to a long DRX cycle when a certain number of cycles are needed in a short DRX cycle. Accordingly, the base station may configure information according to DRX cycles (DRX cycle, on duration, DRX cycle timer, etc.) 6010 to 6060 according to the frequency band to be switched, and the frequency band switching rule may be included in the C-DRX configuration. For example, this can be expressed in the order of band #1, band #2, band #3, and the like, or the order of csb#1, csb#2, csb#3, and the like.

Alternatively, the order of band switching may be completely delegated to the physical layer according to an embodiment. In this case, the terminal operates with common DRX cycle and DRX cycle timers, and determines BW and CSB according to the L1 control signal. The terminal may query BW to change to L1 before one DRX cycle timer expires.

Alternatively, during RRC connection establishment or RRC connection reestablishment, the terminal may request L1 to set up a plurality of BW (CSBs) and the order thereof. At the expiration of one DRX cycle timer or the end of a DRX cycle, the terminal switches BW (CSB) according to the order. If the terminal re-expands the BW according to the BW reconfiguration control signal of the base station or according to a condition pre-configured in the terminal, the BW (CSB) is switched from the expanded BW again in order. When a DRX cycle of a minimum BW (CSB) or a DRX cycle timer expires after all BW (CSB) have been switched, the terminal a) switches to long DRX while maintaining the minimum BW (CSB), b) switches to long DRX by switching to BW (CSB) of a separately configured long DRX, or c) switches to idle DRX.

On the other hand, without introducing a new C-DRX configuration, the existing LTE C-DRX configuration and operation may be maintained and BW change operation is controlled with additional L1 settings. According to an embodiment, the C-DRX configuration to be controlled by RRC is the same, but the base station may configure information (BW, SRB, subframe number, etc.) for BW handover in the on-duration by using the L1 signal. According to another embodiment, the base station may configure information (BW, SRB, etc.) for BW handover, which is reduced every time a short DRX cycle is encountered, by using the L1 signal. According to a further embodiment, the base station may configure BW connected to the short DRX cycle and BW connected to the long DRX cycle by using the L1 signal.

The modified operation of C-DRX assumes that there are different parameters for BW in one DRX configuration. In one aspect, different DRX configurations of BW may be used for more free DRX configurations. In this case, the terminal should operate while viewing a plurality of DRX configurations at the same time, and it is necessary to determine which DRX configuration has priority according to a predetermined rule in order to prevent confusion of operations according to the plurality of DRX configurations.

Fig. 61 is a diagram illustrating an example of DRX settings for wideband and narrowband according to an embodiment of the present disclosure.

Referring to fig. 61, illustrated are states in which wideband DRX 6110 and 6115 and narrowband DRX 6120 and 6125 are configured, respectively. The terminal receives the DRX configurations of the two bands and must follow one of the two DRX configurations for subframes in which a collision operation occurs. If power consumption is emphasized, the terminal may prefer a narrowband DRX configuration over a wideband DRX configuration.

Fig. 62 and 63 are diagrams illustrating examples of DRX settings and priority rules for wideband and narrowband according to various embodiments of the present disclosure.

Referring to fig. 62, an operation is shown in which when both the wideband on duration 6210 and the narrowband on duration 6220 are configured in one subframe, the terminal follows the narrowband on duration configuration 6210 and monitors the DL signal by configuring the narrowband csb#1.

Referring to fig. 63, on the other hand, in the case where the data transmission amount is more important, fig. 63 shows an operation in which when both the wideband on-duration 6310 and the narrowband on-duration 6320 are configured in one subframe, the terminal follows the wideband on-duration configuration 6310 and monitors the DL signal by switching to wideband csb#2. In order to support the different configurations as shown in fig. 62 and 63, the base station may also configure the terminal with priority information between DRX of a frequency band through RRC.

If a DL signal is not received in the DRX configuration for each frequency band and its operation, the terminal starts an inactivity timer. If the inactivity timer for each frequency band is set, the terminal a) may start the inactivity timer for the corresponding frequency band when the DL signal for the frequency band is not received, or b) may start the inactivity timer for each frequency band when the DL signal for the frequency band is not received.

If the inactivity timer is set to a single value regardless of the frequency band, the condition for determining DRX inactivity may be determined to be at least one of: 1) The inactivity timer is started only when no DL signal is received in all frequency bands (CSBs of all configurations), or 2) the inactivity timer is started only when no DL signal corresponding to a prioritized frequency band (CSB) is received.

In the present disclosure, the type of DL signal to be monitored with respect to DRX operation is determined in a standard or may be configured by a base station. If a DL signal that should not be monitored with respect to the DRX operation is received, it can be considered that the DL signal is not received in the DRX operation.

In the BW adaptation and power saving procedure proposed in the present disclosure, there is also a need for a configuration that associates one or more bands configured for scheduling with the DRX procedure.

According to various embodiments presented, the configuration scheme associated with the DRX procedure may be changed. The various embodiments are generally categorized as follows, and the DRX procedure association configuration may vary according to such categorization.

A. In the case where the timing of the terminal switching from band 1 to band 2 depends on the L1/MAC signal of the base station, and the timing of switching from band 2 to band 1 also follows the L1/MAC signal of the base station:

since the band ID is included in the L1/MAC signal, it is not related to the separate DRX configuration. That is, DRX may operate in common regardless of frequency bands. However, when a reception error of the L1/MAC signal of the base station occurs, the base station may configure a specific frequency band (e.g., frequency band 1) for a fallback (fallback) operation. At this time, the base station may include a backoff band in the DRX configuration.

B. In the case where the timing of the terminal switching from band 1 to band 2 depends on the L1/MAC signal of the base station, and the timing of the switching from band 2 to band 1 follows an inactivity timer:

when the terminal is handed over from band 1 to band 2, there is no need to configure band 2 associated with DRX. However, when switching from band 2 to band 1, the base station configures DRX to operate in band 1 because it follows a timer. The terminal should follow the inactivity timer of band 2 after switching to band 2 and may be configured by the base station to operate according to one of the following: 1) an inactivity timer that uses DRX in common, 2) an inactivity timer that is configured for band 2 alone, 3) an inactivity timer that uses DRX with a scaling value, or 4) an inactivity timer that is configured for band 1 alone. The scaling value may be indicated by the DRX configuration or a separate configuration.

C. In the case where the switching from band 1 to band 2 depends on the L1/MAC signal of the base station (but the control channel reception timing is configured separately), and the switching from band 2 to band 1 also depends on the L1/MAC signal of the base station (but the control channel reception timing is configured separately):

In this case, a DRX cycle and an on-duration common to the frequency bands or a DRX cycle and an on-duration of each frequency band should be configured. In the case of band sharing, no separate band configuration is required for DRX configuration. If DRX is configured for each band, configuration is performed by at least one of the following methods: 1) matching the DRX configuration with the number of bands and indicating the bands in each DRX configuration, 2) setting one DRX configuration and indicating the bands of operation for on-duration and off-duration included in the DRX configuration, 3) setting one DRX configuration and indicating the bands of each of short DRX cycle and long DRX cycle included in the DRX configuration, or 4) setting one DRX configuration and indicating the bands of each of on-duration, short DRX cycle, and long DRX cycle included in the DRX configuration.

In the setup and procedure proposed by the present invention, layer 2 of the terminal may not need to know the actual location and size of the frequency band. That is, the physical information of the band is not visible at layer 2, but the logical position and size may be set. Layer 2 may construct a control channel or a transport channel based on logical band location/size information. In addition, the terminal may manage BW information in a list for DRX operation and display it by index.

In the examples presented in this disclosure, it has been assumed that most terminals are not able to monitor narrowband and wideband BW simultaneously. However, depending on the capabilities of the terminal, both narrowband and wideband BW may be monitored in some cases.

Meanwhile, BW provided through the L1 signal and maximum BW of the terminal according to the terminal capability may be different. Thus, when multiple BW-specific DRX configurations are received, the terminal may operate simultaneously for the on duration of one or more BW-specific DRX configurations within the maximum BW of the terminal capability. The on-duration of the DRX configuration exceeding the maximum BW of the terminal capability is excluded from the monitoring. For this operation, the priority of the BW-specific DRX configuration may be configured to the terminal by the base station.

Fig. 64 is a flowchart illustrating an operation of a terminal according to an embodiment of the present disclosure.

Referring to fig. 64, during the RRC connection setup procedure S6410, the terminal requests and acquires information on the location of an operation BW or Control Subband (CSB) from the physical layer in operations S6420 and S6430.

In operation S6440, the terminal receives a DRX configuration per BW or a configuration of parameters for per BW in DRX from the base station based on the acquired information or by reporting the acquired information to the base station.

When the connection is completed, the terminal starts an operation for short DRX in C-DRX. In operation S6450, the terminal performs PDCCH monitoring on each subframe to receive a control signal of the base station. Then, the terminal determines whether the reception of the DL signal is successful in operation S6460.

If the reception of the DL signal is successful, the terminal continuously performs PDCCH monitoring. In some cases, there may be cases where: while PDCCH monitoring is successfully performed, another BW or CSB is monitored under L1 control or RRC control.

If the DL signal is not received as a result of PDCCH monitoring, the terminal updates DRX parameters such as an inactivity timer and a DRX cycle timer in operation S6465. If BW handover is required due to the condition of the inactivity timer or BW handover timer being satisfied in operation 6470, the terminal checks whether it satisfies the short DRX termination condition in operation S6475. The condition corresponds, for example, to a case where PDCCH monitoring fails at the minimum BW and there is thus no further narrowing BW or a case where the short DRX cycle timer expires.

If the short DRX termination condition is not satisfied in operation 6470, the terminal reduces BW and resumes the short DRX operation in operation S6480.

If the short DRX termination condition is satisfied, the terminal starts long DRX in operation S6485. The long DRX operation is performed with minimum or configured BW and is generally similar to LTE long DRX operation. In operation S6490, the terminal monitors a PDCCH according to the long DRX. If the DL signal is not successfully received in operation S6491, the terminal determines whether a long DRX termination condition is satisfied in operation S6492. If the long DRX termination condition is satisfied, the terminal switches to the idle mode in operation S6493.

-a method for individually setting conditions determining inactivity in wide BWP:

BW adaptation or handover operations of the present disclosure are different from SCell addition/release in existing CA, as described below. In CA, the PCell is always activated and the terminal monitors the PCell. However, in case of BW handover, the terminal should transmit and receive control signals such as RRC signals and MAC CEs to and from the base station even though moving in any frequency band. Therefore, even if the terminal is switched from one frequency band (band 1) to another frequency band (band 2) and there is no data traffic in band 2, the terminal can receive the RRC/MAC control signal of the base station. However, receiving the RRC/MAC control signal of the base station in band 2, which is a narrowband, affects the power consumption of the terminal. Thus, when determining inactivity in band 2, the terminal may operate by: 1) control channel activity for transmitting only RRC/MAC control signals of a base station is not reflected in an inactivity timer operation, 2) scheduling allocation lower than a certain Physical Resource Block (PRB) is reflected in an inactivity timer operation, 3) when a certain number of base station signals (or a certain number of transmissions) are received within a certain duration, 4) is reflected in an inactivity timer operation only for a specific DCI format, or 5) it is determined whether to be reflected in an inactivity timer operation by a separate instruction of a base station.

-dual timer setting:

described above is a timer operation for switching from a wide band to a narrow band. The switch from narrowband to wideband may be indicated by a DCI/MAC signal of the base station. However, when an error occurs in receiving the DCI/MAC signal, the terminal should switch from wideband to narrowband for backoff. However, the base station may set the timer value differently, as the requirements for the two cases may be different. That is, when a DCI/MAC signal for switching from narrowband to wideband is received during monitoring, the terminal starts the timer #1. If the terminal does not receive the base station signal in the broadband until the timer #1 expires while performing the band switching operation, the terminal returns to the narrowband.

On the other hand, a terminal that successfully receives a base station signal in a broadband and then does not receive the base station signal after the end of the on-duration starts the timer #2. When timer #2 expires, the terminal switches to the narrowband. In general, it is advantageous that the value of timer #1 is shorter than the value of timer #2 because of the fast backoff in case of error.

Fig. 65 illustrates DRX operation for TTI change according to an embodiment of the present disclosure.

Referring to fig. 65, a Transmission Time Interval (TTI) refers to a time required to transmit one or more Transport Blocks (TBs), and is generally used as a basic time unit for performing scheduling and HARQ operations in a MAC. The terminal receives the TTI information in advance in the initial access process, or receives the default TTI and BW information through SI.

For example, a normal TTI of length 1ms may be set as the base TTI. In addition, the terminal may receive additional TTI and BW information through an RRC message during a random access procedure or after RRC connection establishment is completed. For example, the additional TTI can be set to a short TTI of length 0.5 ms.

Parameters for expressing DRX operation in LTE are expressed in units of subframes. Referring to the normal TTI case 6510 of fig. 65, it can be seen that the on duration is represented by 2ms and the DRX cycle is represented by 6 ms.

When the same DRX parameter expression scheme as LTE is directly imported into 5G, the TTI is set to a short TTI, as shown in short TTI case a 6520, and the terminal monitors the PDCCH during an on-duration of 2ms within the same DRX cycle (6 ms). Although the number of PDCCH monitoring is twice in the same on-duration (2 ms) in the normal TTI case, in the short TTI case a, the TTI length is reduced to half, so the number of PDCCH monitoring is increased to four. However, since the same PDCCH monitoring opportunity is not maintained, power consumption of the terminal may be increased.

In the short TTI case B6530, the on-duration is reduced from 2ms to 1ms according to the reduced TTI, and the number of PDCCH monitoring is also reduced to two within one on-duration. However, since the DRX cycle is also reduced from 6ms to 3ms according to the reduced TTI, PDCCH monitoring is still set four times for the same time as in the normal TTI case. Thus, the power consumption of the terminal is unchanged between the short TTI case a 6520 and the short TTI case B6530.

Accordingly, the present disclosure proposes the following method. That is, among the DRX parameters, a timer (on duration, inactivity timer, etc.) related to PDCCH monitoring is represented by a TTI, and other parameters are represented by subframes.

Referring to the short TTI case C6540, the on-duration is reduced from 2ms to 1ms compared to the normal TTI, and the number of PDCCH monitoring is also kept twice for one on-duration. Further, the number of PDCCH monitoring remains twice compared to the normal TTI within 6ms of the DRX cycle. In detail, the on duration, inactivity timer, ULRetransmissionTimer, startOffset, etc. may be represented by a TTI, and the DRX cycle, shortCycleTimer, etc. may be represented by a subframe.

The TTI length may be set by SI or RRC, but for dynamic scheduling, additional TTI or PDCCH resource settings may be performed in the physical layer L1. However, if the TTI length is dynamically changed according to the additional TTI/PDCCH resource setting, a delay may occur in recalculating the timer on the L2 layer. This delay may cause problems when scheduling/HARQ operations occur in short TTIs. Accordingly, the present disclosure proposes a method of not including a TTI that is dynamically changed according to an L1 signal in a MAC timer calculation. According to an embodiment, a change within a specific time length set through RRC is not included in the MAC timer calculation, and a change longer than the specific time length may be included in the MAC timer calculation.

According to an embodiment, the base station may set an RRC message to the terminal to define the length of the TTI of the specific timer. For example, the on duration may be set to the shortest TTI (0.25 ms), the inactivity timer may be set to the shorter TTI (0.5 ms), and the DRX cycle may be set to the normal TTI (1.0 ms). Further, some parameters may be specified in advance in the standard. For example, the on-duration may depend on the length of the mini-slot set in L1, and the DRX cycle may be specified to follow the length of the slot set in L1.

According to an embodiment, some parameters required for the DRX procedure may be fixed in time units, while other parameters may be set to change time units according to numerology. The base station may fix DRX cycles, shortcycletimers, etc. in units of subframes. The on duration, inactivity timer, ul retransmission timer, and StartOffset may be expressed in units of [ slot, mini-slot ], and which unit to use may be determined according to any combination of control channel, frequency band, index in DCI, and TTI set by the base station. For example, if the terminal receives a control channel in band 1 of the eMBB, the on-duration value 4 is considered to be 4 slots, and if the terminal receives a control channel in band 2 of the URLLC, the same on-duration value 4 is understood to be 4 mini-slots.

Fig. 66 is a diagram illustrating an example of determining TTI values based on control channel monitoring periodicity and transmission duration according to an embodiment of the disclosure.

Referring to fig. 66, the value of the TTI may be differently determined according to the control channel monitoring periodicity and transmission duration.

In cases (a) 6610 and (b) 6620 in fig. 66, the data channels are allocated only in the control channel observation period so that the scheduled transmission period is equal to the control channel observation period. Thus, the TTI is equal to the control channel observation period. However, in case (c) 6630 of fig. 66, the transmission duration is indicated to be longer than the control channel observation period, so that the scheduled transmission period is ambiguous.

This may vary depending on the control of the base station. If the base station indicates the terminal on a transport block having a longer transmission duration than the control channel observation period so as not to observe overlapping control channels, the TTI is equal to the indicated transmission duration. However, if the base station instructs the terminal to observe a control channel observation period even during the transmission duration, the base station may schedule the terminal every control channel observation period. Thus, in this case, the TTI is the same as the control channel observation period.

A detailed embodiment regarding an operation of switching frequency bands based on the timer as shown in fig. 54, 55, 56, and 60 will be described below. The timer may be a new timer, such as a band switch timer or a band availability timer, or may be an existing timer, such as a DRX inactivity timer or a DRX short cycle timer.

Fig. 67 is a diagram illustrating a timer-based band switching operation according to various embodiments of the present disclosure.

Examples 4 to 1

Referring to fig. 67, embodiment 4-1 shows the operation procedure supporting case a 6710.

The MAC entity may be configured to have a DRX function for controlling PDCCH monitoring of the UE through RRC. If the DRX is configured while the UE is in the RRC_CONNECTED state, the MAC entity may discontinuously monitor the PDCCH according to the described DRX operation. When using DRX operation, the MAC entity should monitor the PDCCH by using a specific frequency band at a specific time according to specific requirements. At least one of the following parameters is configured for DRX operation: drx_ BandIndex, onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle, drxStartOffset, drxShortCycleTimer, shortDRX-Cycle.

The drx_band index related to the frequency band may be included in the DRX configuration, or may be defined with an index of a frequency band configured as a default frequency band or a primary frequency band in the frequency band configuration included in the RRC connection (re) configuration procedure, not included in the DRX configuration.

For example, it may be expressed as drx_bandindex=defaultb and index, or drx_bandindex=primarybandindex.

If the DRX cycle is configured, the MAC entity of the UE operates during the active time if:

when at least one of onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, drx-ulremossiontimer and mac-contentionresolution timer is running,

when a scheduling request (scheduling request, SR) is sent to PUCCH and suspended,

-when UL grant for an unsent HARQ retransmission can occur, and

-when generating a control signal for a first transmission on the PDCCH after receiving the RAR.

If DRX is configured, the MAC entity of the UE performs the following operations in each subframe (or slot, symbol, or time unit set by RRC).

When receiving a DRX command MAC CE or a long DRX command MAC CE,

the onduration Timer and the drx-Inactivity Timer are stopped.

When DRX-Inactivity Timer expires or a DRX command MAC CE is received,

■ If a short DRX cycle is configured, the drxShortCycleTimer is (re) started and the short DRX cycle is used.

■ If the short DRX cycle is not configured, a long DRX cycle is used.

-using a long DRX cycle when drxShortCycleTimer expires.

When drxShortCycleTimer has not expired and a long DRX command MAC CE is received,

the drxShortCycleTimer is stopped and a long DRX cycle is used.

-starting onduration timer when UE is using short DRX cycle and the following equation is satisfied according to current SFN and subframe value.

■ [ (SFN x 10) +subframe number ] module (short drx-Cycle) = (drxStartOffset) module (short drx-Cycle).

-starting onduration timer when the UE is using a long DRX cycle and the following equation is satisfied according to the current SFN and subframe value.

■ [ (SFN x 10) +subframe number ] module (longDRX-Cycle) =drxstartoffset.

The MAC entity of the UE monitors the PDCCH in the subframe (or slot, symbol, or time unit set by RRC) where the PDCCH is present at the active time and in the frequency band indicated by drx_bandindex. If the PDCCH indicates DL transmission in the subframe or if DL allocation is set in the subframe, the UE starts a HARQ RTT timer for a corresponding HARQ process and stops a drx-retransmission timer for the same HARQ process.

If the PDCCH indicates UL transmission in the subframe or if UL grant is set in the subframe, the UE starts a UL HARQ RTT timer for HARQ processes of a subframe including the last retransmission of the corresponding PUSCH transmission. In addition, the UE stops drx_ul retransmission timer for the same HARQ process.

If the PDCCH indicates a new transmission, the UE (re) starts the drx-InactivityTimer.

Examples 4 to 2

Example 4-2 shows the operation procedure supporting case B6720 in fig. 67.

The MAC entity may be configured to have a DRX function for controlling PDCCH monitoring of the UE through RRC. If the DRX is configured while the UE is in the RRC_CONNECTED state, the MAC entity may discontinuously monitor the PDCCH according to the described DRX operation. When using DRX operation, the MAC entity should monitor the PDCCH by using a specific frequency band at a specific time according to specific requirements. At least one of the following parameters is configured for DRX operation: onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle, drxStartOffset, drx _BandIndex_longDRX-Cycle, drxShortCycleTimer, shortDRX-Cycle.

The drx_band index_long DRX-Cycle related to the frequency band may be included in the DRX configuration, or may be defined with an index of a frequency band configured as a default frequency band or a primary frequency band among frequency band configurations included in the RRC connection (re) configuration procedure, not included in the DRX configuration.

For example, it may be expressed as drx_bandindex_longdrx-cycle=defaultb and index, or drx_bandindex_longdrx-cycle=primarybandindex.

when a Scheduling Request (SR) is transmitted to PUCCH and suspended,

-when UL grant for an unsent HARQ retransmission can occur, and

When receiving a DRX command MAC CE or a long DRX command MAC CE,

the onduration Timer and the drx-Inactivity Timer are stopped.

When DRX-Inactivity Timer expires or a DRX command MAC CE is received,

■ If the short DRX cycle is not configured, a long DRX cycle is used.

-using a long DRX cycle when drxShortCycleTimer expires.

the drxShortCycleTimer is stopped and a long DRX cycle is used.

-starting onduration timer when UE is using long DRX cycle and the following equation is satisfied according to current SFN and subframe value.

■ [ (SFN x 10) +subframe number ] module (longDRX-Cycle) =drxstartoffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot, symbol, or time unit set by RRC) in which the PDCCH exists during the active time, and monitors the PDCCH in a frequency band indicated by drx_band_index_long DRX-Cycle if a long DRX Cycle is used. If the PDCCH indicates DL transmission in the subframe or if DL allocation is set in the subframe, the UE starts a HARQ RTT timer for a corresponding HARQ process and stops a drx-retransmission timer for the same HARQ process.

Examples 4 to 3

Embodiment 4-3 shows an operation procedure supporting both case a 6710 and case B6720 in fig. 67.

The MAC entity may be configured to have a DRX function for controlling PDCCH monitoring of the UE through RRC. If the DRX is configured while the UE is in the RRC_CONNECTED state, the MAC entity may discontinuously monitor the PDCCH according to the described DRX operation. When using DRX operation, the MAC entity should monitor the PDCCH by using a specific frequency band at a specific time according to specific requirements. At least one of the following parameters is configured for DRX operation: onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle, drxStartOffset, drx _BandIndex_longDRX-Cycle, drxShortCycleTimer, shortDRX-Cycle, drx_BandIndex_short DRX-Cycle.

The drx_band index_longdrx-Cycle or drx_band index_shortdrx-Cycle related to the frequency band may be included in the DRX configuration, or may be defined with an index of a frequency band configured as a default frequency band or a main frequency band in the frequency band configuration included in the RRC connection (re) configuration procedure, not included in the DRX configuration.

For example, it may be expressed as drx_bandindex_short drx-cycle=defaultb and index, or drx_bandindex_longdrx-cycle=primarybandindex.

when a Scheduling Request (SR) is transmitted to PUCCH and suspended,

-when UL grant for an unsent HARQ retransmission can occur, and

When receiving a DRX command MAC CE or a long DRX command MAC CE,

the onduration Timer and the drx-Inactivity Timer are stopped.

When DRX-Inactivity Timer expires or a DRX command MAC CE is received,

■ If the short DRX cycle is not configured, a long DRX cycle is used.

-using a long DRX cycle when drxShortCycleTimer expires.

the drxShortCycleTimer is stopped and a long DRX cycle is used.

■ [ (SFN x 10) +subframe number ] module (longDRX-Cycle) =drxstartoffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot, symbol, or time unit set by RRC) in which the PDCCH exists for an active time, and monitors the PDCCH in a frequency band indicated by drx_band index_short DRX-Cycle if a short DRX Cycle is used, or in a frequency band indicated by drx_band index_long DRX-Cycle if a long DRX Cycle is used. If the PDCCH indicates DL transmission in the subframe or if DL allocation is set in the subframe, the UE starts a HARQ RTT timer for a corresponding HARQ process and stops a drx-retransmission timer for the same HARQ process.

Examples 4 to 4

Examples 4-4 show the operation procedure supporting case B6720 in fig. 67.

when a Scheduling Request (SR) is transmitted to PUCCH and suspended,

-when UL grant for an unsent HARQ retransmission can occur, and

When receiving a DRX command MAC CE or a long DRX command MAC CE,

the onduration Timer and the drx-Inactivity Timer are stopped.

When DRX-Inactivity Timer expires or a DRX command MAC CE is received,

■ If the short DRX Cycle is not configured, a long DRX Cycle is used and a band indicated by the drx_BandIndex_longDRX-Cycle is used.

When the drxShortCycleTimer expires, a long DRX Cycle is used and the band indicated by drx_bandindex_longdrx-Cycle is used.

-when drxShortCycleTimer has not expired and a long DRX command MAC CE is received

The drxShortCycleTimer is stopped, a long DRX Cycle is used, and the band indicated by the drx_band index_long DRX-Cycle is used.

■ [ (SFN x 10) +subframe number ] module (longDRX-Cycle) =drxstartoffset.

The MAC entity of the UE monitors the PDCCH in a subframe (or slot, symbol, or time unit set by RRC) in which the PDCCH exists during the active time. If the PDCCH indicates DL transmission in the subframe or if DL allocation is set in the subframe, the UE starts a HARQ RTT timer for a corresponding HARQ process and stops a drx-retransmission timer for the same HARQ process.

Examples 4 to 5

Examples 4-5 show the operational procedure supporting case a 6710 and case B6720 in fig. 67.

The drx_band index_longdrx-Cycle or drx_band index_shortdrx-Cycle related to the frequency band may be included in the DRX configuration, or may be defined with an index of a frequency band configured as a default frequency band or a main frequency band in the frequency band configuration included in the RRC connection (re) configuration procedure, not included in the DRX configuration. For example, it may be expressed as drx_bandindex_short drx-cycle=defaultb and index, or drx_bandindex_longdrx-cycle=primarybandindex.

when a Scheduling Request (SR) is transmitted to PUCCH and suspended,

-when UL grant for an unsent HARQ retransmission can occur, and

When receiving a DRX command MAC CE or a long DRX command MAC CE,

the onduration Timer and the drx-Inactivity Timer are stopped.

When DRX-Inactivity Timer expires or a DRX command MAC CE is received,

■ If a short DRX Cycle is configured, the drxShortCycleTimer is (re) started, the short DRX Cycle is used, and the band indicated by the drx_BandIndex_ShortDRX-Cycle is used.

-when the drxShortCycleTimer expires, using the long DRX Cycle and using the frequency band indicated by drx_bandindex_longdrx-Cycle.

■ [ (SFN x 10) +subframe number ] module (longDRX-Cycle) =drxstartoffset.

Examples 4 to 6

Examples 4-6 illustrate the procedure supporting case C6730 in fig. 67.

The MAC entity may be configured to have a DRX function for controlling PDCCH monitoring of the UE through RRC. If the DRX is configured while the UE is in the RRC_CONNECTED state, the MAC entity may discontinuously monitor the PDCCH according to the described DRX operation. When using DRX operation, the MAC entity should monitor the PDCCH using a specific frequency band at a specific time according to specific requirements. At least one of the following parameters is configured for DRX operation: drx_ BandIndex, onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimer, drx-ULRetransmissionTimer, longDRX-Cycle, drxStartOffset, drxShortCycleTimer, shortDRX-Cycle.

when a Scheduling Request (SR) is transmitted to PUCCH and suspended,

-when UL grant for an unsent HARQ retransmission can occur, and

When receiving a DRX command MAC CE or a long DRX command MAC CE,

the onduration Timer and the drx-Inactivity Timer are stopped.

-when the current active frequency band is not equal to the frequency band indicated by drx_bandindex;

■ If the drx-Inactivity Timer expires,

frequency bands indicated by drx_bandindex are used, and

the drx-inactivatytimer is (re) started.

-when the current active frequency band is equal to the frequency band indicated by drx_bandindex;

■ If the DRX-Inactivity Timer expires or if a DRX command MAC CE is received,

if a short DRX cycle is configured, drxShortCycleTimer is (re) started and the short DRX cycle is used.

If the short DRX cycle is not configured, the long DRX cycle is used.

■ If drxShortCycleTimer expires, a long DRX cycle is used.

■ If the drxShortCycleTimer has not expired, and if a long DRX command MACCE is received,

the drxShortCycleTimer is stopped and a long DRX cycle is used.

■ The onDurationTimer is started when the UE is using a short DRX cycle and the following equation is satisfied according to the current SFN and subframe value.

[ (SFN 10) +subframe number ] module (short drx-Cycle) = (drxStartOffset) module (short drx-Cycle).

■ The onDurationTimer is started when the UE is using a long DRX cycle and the following equation is satisfied according to the current SFN and subframe value.

[ (SFN x 10) +subframe number ] module (longDRX-Cycle) =drxstartoffset.

In the timer-based inter-band handover operation of the present disclosure, a frequency band to which the UE moves due to expiration of the timer may be determined according to one of the following methods.

1) In case of switching from band 1 to band 2, band 1 is returned due to expiration of the timer.

2) Setting a frequency band for handover per timer

3) Returning to the previous band due to expiration of the timer

4) Returning to a frequency band of given priority due to expiration of a timer

The timer-based inter-band handover operation of the present disclosure is as follows.

Fig. 68 is a diagram illustrating a timer-based band switching operation according to an embodiment of the present disclosure.

Referring to fig. 68, when a given condition or a condition of base station configuration is satisfied, the terminal triggers a timer for one frequency band in operation S6810. Some operational characteristics of the timer, such as the timer increase/decrease time, the timer increase/decrease value, and the timer expiration value, may be predefined or configured by the base station.

The terminal may start a timer or increase or decrease the timer value depending on whether the condition is met. When the current value of the timer reaches the expiration value of the timer, the terminal switches from the current frequency band (first frequency band) to another frequency band (second frequency band) in operation S6820. Further, the terminal stops the timer operation for the first frequency band.

The second frequency band to which the terminal is to be handed over may be given in advance or configured by the base station.

Fig. 69 is a diagram illustrating another timer-based band switching operation according to an embodiment of the present disclosure.

Referring to fig. 69, when the terminal receives a scheduling instruction for a first frequency band from the base station in operation S6910, the terminal triggers a timer for the first frequency band in operation S6920. The timer increases or decreases by a certain amount of time according to a predetermined rule.

Then, the terminal determines whether the timer expires in operation S6930. If the scheduling indication for the first frequency band is received again even though the timer has not expired, the terminal restarts the timer for the first frequency band.

When the timer value reaches a given timer expiration value, the terminal switches from the first frequency band to the second frequency band in operation S6940. Further, the terminal stops the timer operation for the first frequency band.

Fig. 70 is a diagram illustrating yet another timer-based band switching operation according to an embodiment of the present disclosure.

Referring to fig. 70, when an instruction to switch from a current operation frequency band to a first frequency band is received from a base station in operation S7010, a terminal triggers a timer for the first frequency band in operation S7020. The timer increases or decreases by a certain amount of time according to a predetermined rule.

Then, the terminal determines whether the timer expires in operation S7030. If the scheduling indication for the first frequency band is received again even though the timer has not expired, the terminal restarts the timer for the first frequency band.

When the timer value reaches a given timer expiration value, the terminal switches from the first frequency band to the second frequency band in operation S7040. Further, the terminal stops the timer operation for the first frequency band.

Fig. 71 is a diagram illustrating yet another timer-based band switching operation according to an embodiment of the present disclosure.

Referring to fig. 71, when an instruction to switch to a first frequency band is received from a base station in operation S7110, a terminal triggers a timer for the first frequency band in operation S7120.

If the terminal operating in the first frequency band does not receive a scheduling indication for the first frequency band at a given time in operation S7130, the terminal proceeds with the timer for the first frequency band such that the timer value increases or decreases by a given amount according to a predetermined rule in operation S7140.

If a scheduling indication for the first frequency band is received even though the timer for the first frequency band has not expired, the terminal restarts the timer for the first frequency band. When the timer value reaches a given timer expiration value in operation S7150, the terminal switches from the first frequency band to the second frequency band in operation S7160. Further, the terminal stops the timer operation for the first frequency band.

Fig. 72 is a diagram showing a configuration of a terminal according to an embodiment of the present disclosure.

Referring to fig. 72, the terminal may include a transceiver 7210 for transmitting/receiving signals to/from any other device, and a controller 7220 for controlling all operations of the terminal. In this disclosure, the controller 7220 may be defined as a circuit, an application specific integrated circuit, or at least one processor.

The controller 7220 may perform the above operations according to various embodiments of the present disclosure, including the BW controller 7221, the DRX controller 7222, and the system time controller 7223. For example, the controller 7220 may control the signal flow between the respective blocks to perform the operations according to the first to fourth embodiments described above. However, the controller 7220 and the transceiver 7110 are not necessarily implemented as separate devices, and may be implemented as a single unit in the form of a single chip.

Referring to fig. 73, a base station may include a transceiver 7310, a controller 7320, and a memory 7330 (i.e., a storage device). In this disclosure, a controller may be defined as a circuit, an application specific integrated circuit, or at least one processor.

The transceiver 7310 may transmit and receive signals. The controller 7320 may control the overall operation of the base stations according to the first to fourth embodiments of the present disclosure. For example, the controller 7320 may control signal flows between the respective blocks to perform operations according to the first to fourth embodiments described above.

It should be noted that the structures, processes, operations, functions, etc. described above and illustrated in the figures are not intended to limit the scope of the present disclosure. That is, not to be interpreted as necessarily all elements described or illustrated are necessary for an implementation of the present disclosure.

The above-described operations of the base station and the terminal can be achieved by providing a memory device storing program codes to any component equipped in the base station or the terminal. That is, the controller of the base station or terminal may perform the above-described operations by reading and executing program codes stored in the memory device by a processor or Central Processing Unit (CPU).

The various components, modules, etc. of the entities, base stations, or terminals described herein may be implemented in hardware circuitry (e.g., complementary Metal Oxide Semiconductor (CMOS) based logic), firmware, software, or combinations thereof. In one example, various electrical structures and methods may be implemented using circuits such as transistors, logic gates, and custom semiconductors.

Meanwhile, in the drawings showing the methods of the present disclosure, the order of description does not necessarily correspond to the order of execution, and the relationship of the orders may be changed or executed in parallel.

In addition, the figures illustrating the methods of the present disclosure may omit some elements and include only some elements within the scope of the present disclosure.

Furthermore, the above-described embodiments of the present disclosure may be combined and executed, or only some of the components thereof may be combined and executed within the scope of the present disclosure.

While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising:

transmitting a capability message to a base station;

receiving Downlink Control Information (DCI) for band switching from a base station;

performing a band switch to a second band indicated by the DCI based on a switch delay time determined based on a bandwidth capability of a terminal;

receiving data from the base station in a second frequency band;

starting a timer associated with the second frequency band for backing off from the second frequency band to the first frequency band configured from the base station; and

in response to expiration of the timer, a band switch to the first band is performed,

wherein the terminal restarts the timer associated with the second frequency band if a scheduling indication for the second frequency band is received before the timer expires.

2. The method of claim 1, wherein a duration of the timer is configured via radio resource control, RRC, signaling.

3. A method performed by a base station in a wireless communication system, the method comprising:

receiving a capability message from a terminal;

transmitting Downlink Control Information (DCI) for band switching to a terminal; and

transmitting data to a terminal in a second frequency band indicated by the DCI,

wherein a timer associated with the second frequency band is started for the terminal to fall back from the second frequency band to the first frequency band configured from the base station;

wherein the band switching to the second band is performed by the terminal on the basis of a switching delay time,

wherein the handover delay time is determined based on the bandwidth capabilities of the terminal,

wherein the band switching to the first band is performed based on expiration of a timer, an

Wherein the timer associated with the second frequency band is restarted in the terminal in case the scheduling indication for the second frequency band is transmitted by the base station before said timer expires.

4. A method as claimed in claim 3, wherein the method further comprises:

the duration of the timer is sent to the terminal via radio resource control, RRC, signaling.

5. A terminal in a wireless communication system, the terminal comprising:

a transceiver; and

a controller coupled with the transceiver and configured to:

a capability message is sent to the base station,

downlink control information DCI for band switching is received from a base station,

performing a band switch to a second band indicated by the DCI based on a switch delay time, the switch delay time being determined based on a bandwidth capability of a terminal,

data is received from the base station in a second frequency band,

starting a timer associated with the second frequency band for backing off from the second frequency band to the first frequency band configured from the base station, and

6. The terminal of claim 5, wherein a duration of the timer is configured via radio resource control, RRC, signaling.

7. A base station in a wireless communication system, the base station comprising:

a transceiver; and

a controller coupled with the transceiver and configured to:

A capability message is received from the terminal and,

transmitting downlink control information DCI for band switching to a terminal, and

wherein a timer associated with the second frequency band is started for the terminal to fall back from the second frequency band to the first frequency band configured from the base station,

wherein the band switching to the second frequency band is performed by the terminal on the basis of a switching delay time, wherein the switching delay time is determined on the basis of the bandwidth capabilities of the terminal,

8. The base station of claim 7, wherein the controller is further configured to send the duration of the timer to the terminal via radio resource control, RRC, signaling.