WO2019139358A1 - Device and method for performing control signaling in wireless communication system - Google Patents

Abstract

The present disclosure relates to a 5^th generation (5G) or pre-5G communication system for supporting a higher data transfer rate beyond the 4^th generation (4G) communication system, such as long term evolution (LTE). According to various embodiments of the present disclosure, an operation method for a transmitter in a wireless communication system comprises the steps of: configuring a message for requesting a packet data convergence protocol (PDCP) status report; transmitting the message to a receiver; and receiving, from the receiver, a PDCP status report for retransmission of PDCP data, according to the message.

Description

Apparatus and method for performing control signaling in a wireless communication system

BACKGROUND OF THE INVENTION [0002] This disclosure relates generally to wireless communication systems, and more specifically to an apparatus and method for performing control signaling in a wireless communication system.

Efforts are underway to develop improved 5G (5th generation) communication systems or pre-5G communication systems to meet the increasing demand for wireless data traffic after commercialization of 4G (4 ^th generation) communication systems. For this reason, a 5G communication system or a pre-5G communication system is referred to as a 4G network (Beyond 4G Network) communication system or a LTE (Long Term Evolution) system (Post LTE) system.

To achieve a high data rate, 5G communication systems are being considered for implementation in very high frequency (mmWave) bands (e.g., 60 gigahertz (60GHz) bands). In the 5G communication system, beamforming, massive MIMO, full-dimensional MIMO, and FD-MIMO are used in order to mitigate the path loss of the radio wave in the very high frequency band and to increase the propagation distance of the radio wave. ), Array antennas, analog beam-forming, and large scale antenna technologies are being discussed.

In addition, in order to improve the network of the system, the 5G communication system has developed an advanced small cell, an advanced small cell, a cloud radio access network (cloud RAN), an ultra-dense network, (D2D), a wireless backhaul, a moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Have been developed.

In addition, in the 5G system, the Advanced Coding Modulation (ACM) scheme, Hybrid Frequency Shift Keying and Quadrature Amplitude Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), and the Advanced Connection Technology (FBMC) ), Non-Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA).

In a wireless communication system, a terminal and a base station transmit or receive data via a wireless channel. To facilitate data communication, the base station may perform scheduling for data communication associated with the terminal and send control signaling to the terminal. Such control signaling must be properly decoded at the receiving end, and the form and / or contents of control signaling need to be promised in advance.

Based on the above discussion, the disclosure provides an apparatus and method for control signaling in a wireless communication system.

The present disclosure also provides an apparatus and method for indicating a 5G (5th generation) state in a non-standalone (NSA) situation in a wireless communication system.

The present disclosure also provides an apparatus and method for performing packet data convergence protocol (PDCP) status reporting from a receiving end to a transmitting end in a wireless communication system.

In addition, the present disclosure provides an apparatus and method for performing uplink retransmission when a UE performs a periodic uplink transmission and a discontinuous reception (DRX) operation.

According to various embodiments of the present disclosure, a method of operating a transmitting end in a wireless communication system includes: establishing a message for requesting a packet data convergence protocol (PDCP) status report; transmitting the message to a receiving end; And receiving a PDCP status report for retransmission of the PDCP data according to the message from the receiving end.

According to various embodiments of the present disclosure, a method of operating a receiving end in a wireless communication system includes receiving from a transmitting end a message for requesting a packet data convergence protocol (PDCP) status report, And receiving a PDCP status report for retransmission of the PDCP data to the transmitting end.

According to various embodiments of the present disclosure, a transmitter-side apparatus in a wireless communication system includes: a controller for setting a message for requesting a packet data convergence protocol (PDCP) status report; a transmitter for transmitting the message to a receiver, And a transmission / reception unit for receiving a PDCP status report for retransmission of PDCP data according to the message.

According to various embodiments of the present disclosure, in a wireless communication system, a receiving end device receives a message for requesting a packet data convergence protocol (PDCP) status report from a transmitting end and, in response to receiving the message, And a transmission / reception unit for receiving a PDCP status report for retransmission of data.

An apparatus and method in accordance with various embodiments of the present disclosure allows a terminal to be connected to a core network (CN) of an appropriate radio access network (RAT) by indicating the 5G state.

The apparatus and method according to various embodiments of the present disclosure enable a receiving end to perform a packet data convergence protocol (PDCP) status report for retransmission to the transmitting end, thereby reducing transmission delay and preventing data loss.

The apparatus and method according to various embodiments of the present disclosure enable the terminal to reduce the power consumption of the terminal by selectively monitoring the control signal from the base station at the time when the retransmission is required.

In the present invention, a method for indicating to which RAT the 5G terminal is connected in a next generation mobile communication system is clearly specified, and a process of setting a CN to which the terminal can connect is specified based on the method. Can be clearly recognized.

1 illustrates an example of a wireless communication system in accordance with various embodiments of the present disclosure.

Figure 2 illustrates protocol layers in a wireless communication system in accordance with various embodiments of the present disclosure.

3 illustrates another example of a wireless communication system in accordance with various embodiments of the present disclosure.

Figure 4 illustrates another example of protocol layers in a wireless communication system in accordance with various embodiments of the present disclosure.

FIG. 5 illustrates an example of a case where a terminal is connected to an evolved packet core (EPC) or a NR core network in a wireless communication system according to various embodiments of the present disclosure.

Figure 6 shows a flow diagram of a terminal for indicating a 5G state in an NSA scenario in a wireless communication system according to various embodiments of the present disclosure.

FIG. 7 shows a signal flow diagram for an example when indicating a 5G state in an NSA scenario in a wireless communication system according to various embodiments of the present disclosure.

8 shows a signal flow diagram for another example of indicating a 5G state in an NSA scenario in a wireless communication system according to various embodiments of the present disclosure.

Figure 9 illustrates the functional separation of base stations in a wireless communication system in accordance with various embodiments of the present disclosure.

10 illustrates separation of protocol functions for CU and DU in a wireless communication system according to various embodiments of the present disclosure.

FIG. 11 shows a signal flow diagram for performing a setup for PDCP status reporting in a wireless communication system in accordance with various embodiments of the present disclosure.

12 illustrates a PDCP header format for applying PDCP polling in a wireless communication system according to various embodiments of the present disclosure.

13 illustrates a format for PDCP status reporting in a wireless communication system in accordance with various embodiments of the present disclosure.

14A shows a flow diagram of a receiving end for processing a PDCP status report in a wireless communication system in accordance with various embodiments of the present disclosure.

14B shows a flow diagram of a transmitting end for processing a PDCP status report in a wireless communication system according to various embodiments of the present disclosure

FIG. 15 illustrates discontinuous reception (DRX) and resource allocation in a wireless communication system in accordance with various embodiments of the present disclosure.

16 illustrates a frame structure for uplink data transmission in a wireless communication system according to various embodiments of the present disclosure.

17 shows a flow diagram of a UE for DRX and periodic uplink transmissions in a wireless communication system in accordance with various embodiments of the present disclosure.

18 shows a configuration of a base station in a wireless communication system according to various embodiments of the present disclosure.

19 shows a configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure.

20 shows a configuration of a communication unit in a wireless communication system according to various embodiments of the present disclosure.

The terms used in this disclosure are used only to describe certain embodiments and may not be intended to limit the scope of other embodiments. The singular expressions may include plural expressions unless the context clearly dictates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by one of ordinary skill in the art. The general predefined terms used in this disclosure may be interpreted as having the same or similar meaning as the contextual meanings of the related art and, unless explicitly defined in the present disclosure, include ideally or in an excessively formal sense . In some cases, the terms defined in this disclosure can not be construed to exclude embodiments of the present disclosure.

In the various embodiments of the present disclosure described below, a hardware approach is illustrated by way of example. However, the various embodiments of the present disclosure do not exclude a software-based approach, since various embodiments of the present disclosure include techniques that use both hardware and software.

The present disclosure relates to an apparatus and method for performing control signaling in a wireless communication system. Specifically, the present disclosure relates to a technique for indicating a 5G (5th generation) state in a non-standalone (NSA) state in a wireless communication system and a technique for performing a packet data convergence protocol (PDCP) Technology, and a technique for performing uplink retransmission in periodic uplink transmission and discontinuous reception (DRX) operations.

The terms used to refer to signals used in the following description, the term channel, the term control information, the term network entity, the term component element, etc., . Accordingly, the present disclosure is not limited to the following terms, and other terms having equivalent technical meanings can be used.

Further, the present disclosure describes various embodiments using terms used in some communication standards (e.g., 3rd Generation Partnership Project (3GPP)), but this is merely illustrative. The various embodiments of the present disclosure can be easily modified and applied in other communication systems as well.

1 illustrates an example of a wireless communication system in accordance with various embodiments of the present disclosure. The wireless communication system shown in FIG. 1 may be a system (e.g., evolved packet system (EPS)) to which LTE radio access technology (RAT) is applied. Hereinafter, in the present disclosure, a system to which LTE radio access technology is applied may be briefly referred to as an " LTE system ".

1, an LTE system may include evolved Node Bs 131, 133, 135 and 137, a mobility management entity (MME) 110, and a serving gateway (S-GW) 120.

The eNB 131 may be connected to the UE 141 via a wireless channel. In the LTE system, since traffic of all users (for example, real-time services such as Voice over IP (VoIP) over the Internet protocol) is transmitted through a shared channel, the eNB 131 determines the buffer status, , Channel state, and the like. For example, in order to achieve a transmission rate of 100 Mbps, an orthogonal frequency division multiplexing (OFDM) scheme can be used in a 20 MHz bandwidth. The eNB 131 can control a plurality of cells. Also, the eNB 131 may determine a modulation scheme and / or a channel coding rate based on a channel state of the UE according to adaptive modulation and coding (AMC). According to various embodiments of the present disclosure, the eNB 131 may include a base station, an access point (AP), a wireless point, a transmission / reception point (TRP) ) &Quot; or other terms having equivalent technical meanings.

The MME 110 manages the mobility of the UE (e.g., UE 141) and can perform various control functions. The MME 110 may be associated with a plurality of eNBs (e.g., eNBs 131, 133, 135 and / or 137). The S-GW 120 may provide a data bearer. The S-GW 120 can create or remove a data bearer under the control of the MME. The MME 110 and the S-GW 120 can perform authentication, bearer management, and process packets for the eNBs 131, 133, 135, and 137, respectively,

A user equipment (UE) 141 is a device used by a user and communicates with the eNB 131 through a wireless channel. In some cases, the UE 141 may be operated without user involvement. That is, the UE 141 is an apparatus for performing machine type communication (MTC), and may not be carried by a user. UE 141 may connect to the external network via eNBs ( eNBs 131, 133, 135 and / or 137) and S-GW 120, for example. According to various embodiments of the present disclosure, the UE 141 may be a terminal, a mobile station, a subscriber station, a remote terminal, a wireless terminal, Quot ;, ") ", or " user device ", or other terms having equivalent technical meanings.

Figure 2 illustrates protocol layers in a wireless communication system in accordance with various embodiments of the present disclosure. The protocol layers illustrated in FIG. 2 may be protocol layers of an LTE system.

2, protocol layers of a UE (e.g., UE 141) in a LTE system include a packet data convergence protocol (PDCP) layer 211, a radio link control (RLC) layer 213, a medium access control (MAC) layer 215, , PHY) 217. Similarly, in LTE systems, the protocol layers of an eNB (e.g., eNB 131) may include PDCP 221, RLC 223, MAC 225, PHY 227.

The PDCP 211 or the PDCP 221 can compress or restore an internet protocol (IP) header based on a robust header compression (ROHC) scheme. The functions of PDCP 211 or PDCP 221 may be summarized as follows, and PDCP 211 or PDCP 221 may perform at least one of the functions illustrated below:

- Header compression and decompression (ROHC)

- Transfer of user data

- an in-sequence delivery of upper layer PDUs (packet data units) at the PDCP re-establishment procedure for RLC AM (acknowledgment mode)

- Order reordering function (for split bearers in DC (RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

- Duplicate detection of lower layer SDUs (service data units) at PDCP re-establishment procedure for RLC AM)

- Retransmission function (PDCP SDUs at handover and for split bearers in DC, PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

- ciphering and deciphering function

- Timer based SDU deletion function (timer-based SDU discard in uplink.)

The RLC 213 or the RLC 223 can perform an automatic repeat request (ARQ) function by reconfiguring the PDU to an appropriate size. The functions of RLC 213 or RLC 223 may be summarized as follows and RLC 213 or RLC 223 may perform at least one of the functions illustrated below:

- Transfer of upper layer PDUs

- ARQ function (Error Correction through ARQ (only for AM data transfer))

- concatenation, segmentation and reassembly of RLC SDUs (only for UM (unacknowledged mode) and AM data transfer)

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

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

- Duplicate detection (only for UM and AM data transfer)

- Error detection (only for AM data transfer)

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

- RLC reset function (RLC re-establishment)

MAC 215 or MAC 225 may be coupled to a plurality of RLC layer devices, multiplex RLC PDUs with MAC PDUs, and demultiplex RLC PDUs from MAC PDUs. The functions of MAC 215 or MAC 225 may be summarized as follows, and MAC 215 or MAC 225 may perform at least one of the functions illustrated below:

Mapping between logical channels and transport channels

- Multiplexing / demultiplexing (MAC SDUs belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on transport channels)

- Scheduling information reporting function

- HARQ function (error correction through HARQ (hybrid ARQ))

- Priority handling between logical channels (one UE)

- Priority handling between UEs by means of dynamic scheduling

- Multimedia broadcast multicast service (MBMS) service identification function (MBMS service identification)

- Transport format selection function (Transport format selection)

- Padding function

PHY 217 or PHY 227 may perform OFDM symbols by performing channel coding and modulation on the upper layer data, and may transmit the generated OFDM symbols through a wireless channel. In addition, the PHY 217 or the PHY 227 may demodulate the OFDM symbols received through the wireless channel, perform channel decoding on the demodulated symbols, and transmit the decoded symbols to an upper layer. In PHY 217 or PHY 227, for additional error correction, HARQ (hybrid ARQ) may be used. According to the HARQ, the receiving end can transmit 1-bit information to the transmitting end indicating whether or not the packet received from the transmitting end has been properly received. Here, one bit of information may be referred to as HARQ ACK (acknowledgment) / NACK (negative ACK) information. The downlink HARQ ACK / NACK information for the uplink transmission is transmitted through the physical HARQ indicator channel (PHICH), and the uplink HARQ ACK / NACK information for the downlink transmission is transmitted through the physical uplink control channel (PUCCH) have. The PUCCH can be used not only for HARQ ACK / NACK but also for transmitting a channel state information (CSI) and a scheduling request (SR) to a base station. The SR is 1-bit information. When a terminal transmits an SR in a resource set in a PUCCH set by the base station, the base station identifies that downlink data to be transmitted by the terminal exists, and allocates uplink resources to the terminal. The UE can transmit a buffer status report (BSR) message through the uplink resource allocated by the BS. The base station can allocate a plurality of SR resources to one terminal.

In addition, the PHY 217 or PHY 227 may be composed of one or a plurality of frequency / carriers, and a technique of simultaneously using a plurality of carriers in one base station may be referred to as a carrier aggregation (CA). When CA technology is applied, one primary carrier and one or more secondary carriers may be used for communication between the UE and the eNB, and the amount of transmission may be increased by the number of subcarriers. Meanwhile, in the LTE system, a cell in a base station using a main carrier may be referred to as a primary cell, and a cell in a base station using a subcarrier may be referred to as a secondary cell (SCell). The CA technology extended to two base stations can be referred to as dual connectivity (DC). DC technology, the UE can simultaneously access the primary E-UTRAN NodeB (MeNB) and the secondary E-UTRAN NodeB (SeNB). Cells belonging to the primary base station may be referred to as a master cell group (MCG), and cells belonging to the secondary base station may be referred to as a secondary cell group (SCG). A representative cell may exist for each cell group. In an NR system such as that described below, the MCG may use LTE RAT and the SCG may be defined to use NR RAT. In other words, the terminal can use LTE RAT and NR NAR RAT at the same time.

Although not shown, the RRC layer may exist as an upper layer of the PDCP 211 and the PDCP 221. The RRC layer may be used for radio resource control to send and receive connection and measurement related configuration control messages. For example, the eNB 131 can instruct the UE to perform measurement using the RRC layer message, and the UE can report the measurement result to the BS using the RRC layer message.

On the other hand, the transmission units of PCell and SCell may be the same or different. For example, in LTE systems, PCell and SCell transmission units can all be 1ms units, but in NR systems, PCell transmission units can be 1ms and SCell transmission units can be 0.5ms units.

The following Table 1 shows the performance of each serving cell (i.e., PCell or SCell) according to the numerology used in each serving cell in NR (or according to subcarrier spacing (SCS) And information on the length of the slot.

In LTE and NR, the following units are used in the frame structure of the radio section (i.e., between the base station and the terminal).

- Radio frame: It has a length of 10 ms and is identified by a system frame number (SFN) in every radio frame.

- Subframe: It has a length of 1 ms, and there are 10 subframes in the radio frame. Identified as a sub-frame number 0-9 within each radio frame.

- Slot: It has a length according to the set value as shown in <Table 1>, and when the base station and the terminal transmit data

3 illustrates another example of a wireless communication system in accordance with various embodiments of the present disclosure.

Referring to FIG. 3, the wireless communication system may include a system in which a new radio (RAT) different from the LTE RAT is applied. According to various embodiments of the present disclosure, NR RAT may refer to a RAT that is capable of achieving a higher data rate and / or a higher reliability and / or lower delay data communication as compared to an LTE RAT. Hereinafter, a system to which NR RAT is applied in the present disclosure may be briefly referred to as an 'NR system. The NR system may include an NR NB (node B) 321 implemented by NR RAT and a NR core network (CN) 311. The NR CN may also be referred to as a 'next generation (NG) CN'. The wireless communication system may also include an NR UE 331 that performs a wireless connection with the NR NB 321, and an MME 313 and an eNB 323 of the LTE system.

The NR NB 321 may be connected to the NR UE 331 over a wireless channel and may provide enhanced services to the UE 331 over a Node B or an eNB (eNB 323, for example). In the wireless communication system, because traffic of users is transmitted through a common channel, the eNB 131 is required to perform scheduling appropriately based on state information such as buffer states, available transmission power states, and channel states of UEs. NR NB 321 can perform communication in a wider bandwidth than LTE and can use OFDM to achieve a higher data rate compared with LTE and can reduce the path loss ( To compensate for path loss, a beam forming technique may be used. The NR NB 321 can control a plurality of cells. Also, the NR NB 321 may determine the modulation scheme and / or the channel coding rate based on the channel state of the UE according to the AMC. According to various embodiments of the present disclosure, the NR NB may also be referred to as a 'gnode ratio (gNodeB, gNB)', '5g (5th generation) node'.

The NR CN 311 can perform functions such as mobility support, bearer setup, and quality of service (QoS) setup. The NR CN 311 manages the mobility of the UE, performs various control functions, and can be connected to a plurality of base stations including the NR NB 321. Also, the NR CN 311 can be connected to the MME 313 via a network interface.

The MME 313 and the eNB 323 may be interconnected via a network interface. The MME 313 and the eNB 323 may perform the same functions as the MME 110 and the eNB 131 of FIG.

The NR UE 331 can access the external network via the NR NB 321 and NR CN 331. According to various embodiments of the present disclosure, the NR UE 331 is a UE capable of using NR RAT, according to various embodiments of the present disclosure, connected to an NR NB (e.g., NR NB 321) (E.g., NR CN 331).

NR NB 321 and NR UE 331 are capable of transmitting and receiving radio signals in the millimeter wave (mmWave) band (eg, 28 GHz, 30 GHz, 38 GHz, 60 GHz). At this time, in order to improve the channel gain, NR NB 321 and NR UE 331 can perform beamforming. Here, beamforming may include transmit beamforming and receive beamforming. That is, the NR NB 321 and the NR UE 331 can impart directivity to a transmission signal or a reception signal. To this end, NR NB 321 and NR UE 331 may select serving through beam search or beam management procedures. After the serving beams are selected, communication may then be performed via a resource in a quasi co-located (QCL) relationship with the resource that transmitted the serving beams.

If the large-scale characteristics of the channel carrying the symbol on the first antenna port can be inferred from the channel carrying the symbol on the second antenna port, then the first antenna port and the second antenna port are in a QCL relationship Can be evaluated. For example, a wide range of characteristics may be used for delay spread, Doppler spread, Doppler shift, average gain, average delay, spatial receiver parameter, Or the like.

Figure 4 illustrates another example of protocol layers in a wireless communication system in accordance with various embodiments of the present disclosure. The protocol layers illustrated in FIG. 4 may be protocol layers of the NR system.

Referring to FIG. 4, the protocol layers of a UE (e.g., UE 331) in the NR system may include NR PDCP 411, NR RLC 413, NR MAC 415, NR PHY 417d. Similarly, the protocol layers of the NR NB (e.g., NR NB 321) in the NR system may include NR PDCP 421, NR RLC 423, NR MAC 425, NR PHY 427.

The functions of the NR PDCP 411 or the NR PDCP 421 may be summarized as follows and the NR PDCP 411 or the NR PDCP 421 may perform at least one of the functions illustrated below:

- Header compression and decompression (ROHC)

- Transfer of user data

- In-sequence delivery of upper layer PDUs

- Out-of-sequence delivery of upper layer PDUs

- Order reordering function (PDCP PDU reordering for reception)

- duplicate detection of lower layer SDUs

- Retransmission of PDCP SDUs

- Ciphering and deciphering function

- Timer based SDU deletion function (timer-based SDU discard in uplink.)

Here, the order reordering function performed in the NR PDCP 411 or the NR PDCP 421 means a function of rearranging the PDCP PDUs received from the lower layer in order based on the PDCP SN (sequence number) And transferring the function or PDUs to the upper layer without reordering them. In addition, the reordering function includes a function of recording lost PDCP PDUs, a function of performing a status report on lost PDCP PDUs, and a function of requesting retransmission of lost PDCP PDUs .

The functions of NR RLC 413 or NR RLC 423 may be summarized as follows, and NR RLC 413 or NR RLC 423 may perform at least one of the functions illustrated below:

Transfer of upper layer PDUs

In-sequence delivery of upper layer PDUs

Out-of-sequence delivery of upper layer PDUs

ARQ function (error correction through ARQ)

The concatenation, segmentation and reassembly of RLC SDUs,

The re-segmentation of RLC data PDUs

Reordering of RLC data PDUs

Duplicate detection

Error detection (protocol error detection)

RLC SDU discard function (RLC SDU discard)

RLC reset function (RLC re-establishment)

Herein, the sequential transmission function performed in the NR RLC 413 or the NR RLC 423 means a function of transmitting RLC SDUs received from a lower layer to an upper layer in order, and one RLC SDU is divided into a plurality of RLC SDUs And to reassemble and deliver the RLC SDUs when the segmented RLC SDUs are received. In addition, the sequential delivery function includes a function of rearranging received RLC PDUs based on an RLC SN or a PDCP SN, a function of recording lost RLC PDUs, a function of performing status reporting of lost RLC PDUs, A function to transmit RLC SDUs up to the lost RLC SDU to the upper layer in order when there is a lost RLC SDU, If the timer has expired, a function of transferring all the RLC SDUs received until the timer starts, to the upper layer in order, or, if a preset timer expires even in the case of a lost RLC SDU, all the RLC SDUs received so far, And a function of transmitting the data to the mobile terminal. In addition, the NR RLC 413 or the NR RLC 423 may process the RLC PDUs in the order in which they receive the RLC PDUs (that is, regardless of the order of the SNs) and forward them to the PDCP 411 or the PDCP 421 in an out-of- , The PDU segments stored in the buffer and / or the PDUs received later can be reconstructed into one complete RLC PDU, and then the reconstructed PDU can be processed and transmitted to the PDCP device. According to various embodiments of the present disclosure, the NR RLC 413 or the NR RLC 423 may not perform the joint function. In this case, the joint function may be performed in the NR MAC (for example, NR MAC 415 or NR MAC 425), or may be replaced by the multiplexing function of the NR MAC layer.

 The non-sequential forwarding function performed in the NR RLC 413 or the NR RLC 423 refers to a function of delivering RLC SDUs received from a lower layer to an upper layer regardless of order. When the RLC SDU is divided into a plurality of RLC SDUs and received A function of reassembling and transmitting the divided RLC SDUs and a function of storing RLC SN or PDCP SN of the received RLC PDUs and recording the lost RLC PDUs by arranging the order.

The NR MAC 415 or NR MAC 425 may be coupled to a plurality of NR RLC layer devices. The functions of the NR MAC 415 or NR MAC 425 may be summarized as follows and the NR MAC 415 or NR MAC 425 may perform at least one of the functions illustrated below:

Mapping between logical channels and transport channels

Multiplexing / demultiplexing of MAC SDUs

Scheduling information reporting function

HARQ (error correction through HARQ)

Priority handling between logical channels (one UE)

Priority handling between UEs by means of dynamic scheduling

MBMS service identification (MBMS service identification)

Transport format selection function (Transport format selection)

Padding function

The NR PHY 417 or the NR PHY 427 can perform OFDM symbols by performing channel coding and modulation on the upper layer data, and transmit the generated OFDM symbols through the wireless channel. The NR PHY 417 or the NR PHY 427 may demodulate the OFDM symbols received through the wireless channel, perform channel decoding on the demodulated symbols, and transmit the decoded symbols to an upper layer.

FIG. 5 illustrates an example of a case where a terminal is connected to an evolved packet core (EPC) or a NR core network in a wireless communication system according to various embodiments of the present disclosure. 5, an EPC (e.g., EPC 521) refers to a core network in an LTE system and may include an MME (e.g., MME 110 or MME 313) and / or an S-GW . And may be connected to the NR core 523 through an EPC 521 dms HSS (home subscriber server) 510.

Referring to FIG. 5, the NR CN 523 includes an Evolved Universal Territorial Radio Access Network (e-UTRAN) (e.g., eNB 531) and an NR radio access network (NR RAN) And NR UEs (eg, NR UE 1 543, NR UE 2 545) that can be connected to NR CN 523 must be able to be concurrently connected to NR CN 523 and EPC 521. In other words, the NR UE shall be able to use a NAS (non-access stratum, NAS) connection for both EPC 521 and NR CN 523.

A terminal that can be connected to at least NR CN 523 may select NAS associated with NR CN 523 when connected to the network. However, NR CN 523 may not support certain functions (e.g., MBMS) supported by EPC 521 of the LTE system. In addition, when a terminal is registered in the EPC 521 and in the NR CN 523, different services can be supported. Therefore, a terminal registered in the NR CN 523 (e.g., NR UE 2 545) needs to be registered in the EPC 521 as needed, and conversely the terminal registered in the EPC 521 (e.g., NR UE 1 543) It needs to be registered in CN 523. A gNB (e.g. gNB 533) may be used or an eNB (e.g., eNB 531) needs to be upgraded for the NR CN 523 connection in order for the NR UE to be able to connect to EPC 521 and NR CN 523.

According to various embodiments of the present disclosure, in a non-standalone (NSA) scenario in which LTE is a master node and NR is a secondary node, the terminal indicates the RAT state as a 5G state or an NR state An apparatus and a method are provided. Here, the RAT state indicates the terminal currently using or camping on a RAT (e.g., 1G, 2G, 3G, 4G or 5G), for example, the terminal currently using or camping on If the RAT is 5G, the RAT state may be a 5G state. According to various embodiments of the present disclosure, the 5G state may also be referred to as "NR state ".

In a 5G standalone scenario, if a terminal camps on an NR cell and is connected to a 5G core (e.g., NR CN 523), the terminal may indicate that the RAT state is a 5G state. On the other hand, in the NSA scenario, for example, one of the following cases may be a candidate that can be indicated as a 5G state:

When the UE connected to the eNB supporting the NSA (eNB 521 for example) receives the configuration information for the NR cell (EN-DC (E-UTRA-NR dual connectivity) )

If the UE in the idle state camping on the eNB supporting the NSA (eNB 521, for example) is likely to receive the setting for the NR cell (the LTE cell associated with the eNB is a cell supporting EN-DC Occation)

If the UE in the IDLE state camping on the eNB supporting the NSA (eNB 521, for example) then goes into NR coverage and searches for NR cells

It is necessary to determine which of the above cases can be indicated as the 5G state. In addition, the indication of the 5G state may be provided to a higher layer (e.g., NAS) in a lower layer (e.g., AS (access stratum)). The NAS can know the RRC status of the AS layer, which means that in certain scenarios, the NAS and the upper layer can be found to be in a 5G state.

Various embodiments of the present disclosure provide a way in which all of the candidates that may be indicated in the 5G state (hereinafter referred to as 5G state indication candidates) can be considered. To this end, NR configuration parameters and NR coverage parameters are defined in various embodiments of the present disclosure, and the values of these parameters can be passed from the AS to the NAS of the terminal.

The NR configuration parameter may indicate whether the terminal connected to the LTE cell has received a setting for NR cells (i.e., whether it has received an EN-DC setting). For example, when a UE connected to an LTE cell receives a setting for NR cells, the value of the NR configuration parameter may be set to on or a value corresponding thereto, and a UE connected to the LTE cell may transmit , The value of the NR configuration parameter may be set to off or a value corresponding thereto. The NR configuration parameter may be used to determine whether the terminal with the LTE cell in the Connected or INACTIVE state has received a setting for the NR cells.

The NR coverage parameter may indicate whether or not the UE enters the coverage of the NR cell and detects NR cells. For example, when the UE enters the coverage of the NR cell and detects NR cells, the value of the NR coverage parameter may be set to ON or a corresponding value, and if the UE enters the coverage of the NR cell and does not detect NR cells If not, the value of the NR coverage parameter may be set to off or a corresponding value. The NR coverage parameter can be used to determine whether a terminal that is idle or inactive with an LTE cell is potentially able to use the NR cell.

Figure 6 shows a flow diagram of a terminal for indicating a 5G state in an NSA scenario in a wireless communication system according to various embodiments of the present disclosure. FIG. 6 illustrates a method of operation of NR UE 331, NR UE 1 543 or NR UE 2 545.

Referring to FIG. 6, in step 601, the UE in the RRC_IDLE state receives system information (e.g., a system information block (SIB) 1). The system information received in step 601 may include information on a public land mobile network (PLMN) and / or a CN to determine a cell to which the terminal camps. For example, SIB1 may include a list of PLMNs for each CN type (e.g., EPC, NR CN). The terminal may camp on a cell supporting an appropriate PLMN based on information about the PLMN and / or the CN.

In step 603, the terminal establishes a connection with the base station. For example, the UE can perform an RRC connection configuration with the base station. In step 603, the terminal can perform setting and additional settings (e.g., CA, DC, and EN-DC settings) for data transmission and reception. According to various embodiments of the present disclosure, step 603 may be omitted. In other words, operations after step 603 can be performed by the terminal in the RRC_IDLE state.

In step 605, the terminal determines whether a parameter (e.g., NR configuration parameter, NR coverage parameter) for indicating the 5G status is used. Hereinafter, the parameter for indicating the 5G state can be briefly referred to as the &quot; 5G state indication parameter &quot;.

If the 5G status indication parameter is not used, in step 607, the terminal transports information acquired from the system information (e.g., SIB1) to the NAS. For example, the terminal may forward the PLMN list for each CN type to the NAS.

In step 609, the terminal performs a CN selection procedure. According to various embodiments of the present disclosure, the terminal may forward information about the received PLMN and / or CN to the NAS of the CN. Here, the CN may be the base station and the default CN, and may be changed to another CN according to the reset. In this case, selection (or reset) of the CN may be performed by the basic CN.

According to various embodiments of the present disclosure, the NAS of the terminal may determine the PLMN and the CN based on a predetermined method, and forward the result to the AS and forward it to the base station via the RRC message. Here, the predetermined method may be a priority-based decision method. For example, the UE can determine the PLMN and the CN based on the black list stored in the UE. The blacklist can be obtained from the NAS message received from the CN and the PLMN-CN mapping information received from the SIB1.

According to various embodiments of the present disclosure, the CN selection procedure illustrated in step 609 may be performed in step 601. [ In this case, step 609 may be omitted.

Thereafter, in step 611, the terminal sets up a connection with the base station (e.g., establishes a radio resource control (RRC) connection), and transmits and receives data in step 613. [

When the 5G status indication parameter is used, in step 615, the terminal determines the value of the 5G status indication parameter. For example, the terminal determines the value of each NR configuration parameter and the NR coverage parameter.

In step 617, the terminal transfers the value of the 5G status indication parameter from the AS to the NAS, and performs the CN selection procedure in step 619. [ According to various embodiments of the present disclosure, the terminal may forward the value of the determined status indication parameter to the NAS of the CN. Here, the CN can be a basic CN and can be changed to another CN according to the reset. In this case, selection (or reset) of the CN may be performed by the basic CN.

According to various embodiments of the present disclosure, the NAS of the terminal may determine the PLMN and the CN based on a predetermined method, and forward the result to the AS and forward it to the base station via the RRC message. Here, the predetermined method may be a priority-based decision method. For example, the UE can determine the PLMN and the CN based on the black list stored in the UE. The blacklist can be obtained from the NAS message received from the CN and the PLMN-CN mapping information received from the SIB1.

According to various embodiments of the present disclosure, the 5G status indication parameter may be used for other purposes than the CN selection, and the terminal may forward information on the determined 5G status indication parameter to the base station or CN.

According to various embodiments of the present disclosure, the CN selection procedure illustrated in step 619 may be performed in step 601. [ In this case, step 619 may be omitted.

Thereafter, in step 611, the terminal sets up a connection with the base station (e.g., establishes an RRC connection), and transmits and receives data in step 613. [

FIG. 7 shows a signal flow diagram for an example when indicating a 5G state in an NSA scenario in a wireless communication system according to various embodiments of the present disclosure. FIG. 7 illustrates a signal flow between CNs 700 including a UE 541 capable of NR RAT, an eNB 531 capable of connecting to NG CN, and a CN of at least one of the base CN and the target CN to be changed.

Referring to FIG. 7, in step 701, the UE 541 receives system information (e.g., SIB1) from the eNB 531 through an initial cell search and determines whether a cell associated with the eNB 531 is a home PLMN (HPLMN). SIB 1 may include a list of PLMNs for each CN type. In other words, since a UE registered in the NR CN also needs to be reconfigured as an EPC in some cases, SIB 1 for CN re-establishment may include a PLMN list for each CN type instead of just a PLMN list. After receiving the system information, the UE 541 selects the PLMN, camps on the selected PLMN, and receives the remaining system information (RMSI). The PLMN has priority in a predetermined pattern as in LTE . &Lt; / RTI &gt;

In step 703, the UE 541 and the eNB 531 perform RRC connection and RRC establishment procedures. The UE 541 for which the current connection is not established (that is, idle) may generate data to be transmitted or may perform an RRC connection establishment (setup) procedure in response to a request from the base station. Although not shown, after the RRC connection, settings related to data transmission and reception and additional settings (e.g., settings related to carrier aggregation (CA), DC, and EN-DC) may be performed.

 In step 705, the UE 541 determines the value of the 5G status indication parameter and forwards the information on the determined value from the AS to the NAS. For example, the UE 541 may determine the value of the NR configuration parameter and / or the NR coverage parameter.

In step 707, the UE 541 may select the CN. For example, the UE 541 may select CN based on at least one of the values of the PLMN, the NR configuration parameter, and the NR coverage parameter for the CN type and for each CN type. According to another embodiment, CN 700 may select CN, in which case step 707 may be omitted.

In step 709, the UE 541 transmits control information related to the CN selection to the CN 700 via the eNB 531. The control information associated with the CN selection may be referred to as a CN RE-DIRECTION REQUEST. If the UE selects the CN in step 707, the control information associated with the CN selection may include information about the selected CN. Alternatively, if the CN 700 selects CN, the control information associated with the CN selection may include at least one of a CN type and a value of a PLMN, an NR configuration parameter, and a NR coverage parameter for each CN type.

In step 711, CN 700 selects CN. For example, the CN 700 may select a CN for the UE 541 based on at least one of the CN type included in the control information associated with CN selection and the value of the PLMN, NR configuration parameter, and NR coverage parameter for each CN type . If the UE 541 has determined the CN, step 711 may be omitted.

In step 713, the CN 700 sends a CN RE-DIRECTION message to the eNB 531. The CN RE-DIRECTION message may include information about the CN determined in step 711. [ The CN RE-DIRECTION message may be included in the INITIAL CONTEXT SETUP message or may include information that may be included in the INITIAL CONTEXT SETUP message.

If it is determined that the CN is to be changed, then in step 715, the eNB 531 forwards a SERVICE REQUEST message to the target CN to be changed. The service request message may be a message for requesting the MME to set up a bearer to provide a service to the terminal. The MME can determine whether to provide the service requested by the terminal.

In step 717, the CN 700 including the changed MME transmits an INITIAL CONTEXT SETUP REQUEST message to the eNB 531 if the changed MME determines to provide the requested service. The initial context setup request message includes information such as QoS information to be applied when setting up a data radio bearer (DRB) and security related information (e.g., a security key and a security algorithm) to be applied to the DRB .

After the CN change is instructed, the eNB 531 transmits a SecurityModeCommand message to the UE 541 in step 719 and receives a SecurityModeComplete message from the UE 541 in step 721. [

When the security setting is completed, in step 723, the eNB 531 transmits an RRConnectionReconfiguration message to the UE 541. [ The RRC connection re-establishment message may include configuration information of the DRB to which the user data is to be processed, and the UE 541 sets up the DRB of the DRB and applies RRConnectionReconfigurationComplete message to the eNB 531 in step 725 .

In step 727, the eNB 531 that has completed the DRB setup with the UE 541 transmits an initial context setup complete message to the MME. In response, the MME sets up the S-GW and the S1 bearer in step 729. [ To configure the S1 bearer, the MME may exchange the S1 Bearer Setup message and the S1 Bearer Setup Response message with the S-GW. Here, the S1 bearer is a data transmission connection established between the S-GW and the eNB 531, and can correspond to DRB on a one-to-one basis.

In step 731, the UE 541 transmits and receives data through the eNB 531 and the S-GW.

As described above, the data transmission process may include three steps of RRC connection setup, security setup, and DRB setup. The base station (eNB 531, for example) may send a RRCConnectionReconfiguration message to provide a new configuration to the terminal (e.g., UE 541) or to add or change the configuration of the terminal.

8 shows a signal flow diagram for another example of indicating a 5G state in an NSA scenario in a wireless communication system according to various embodiments of the present disclosure. FIG. 8 illustrates a signal flow between a UE 541 capable of NR RAT, an eNB 531 capable of connecting to NG CN, and a CN 700 including at least one of a basic CN and a target CN to be changed.

Referring to FIG. 8, in step 801, the UE 541 receives system information (e.g., SIB1) from the eNB 531 through an initial cell search and determines whether a cell associated with the eNB 531 is a home PLMN (HPLMN). SIB 1 may include a list of PLMNs for each CN type. In other words, since a UE registered in the NR CN also needs to be reconfigured as an EPC in some cases, SIB 1 for CN re-establishment may include a PLMN list for each CN type instead of just a PLMN list. After receiving the system information, the UE 541 selects the PLMN, camps on the selected PLMN, and receives the remaining system information (RMSI). The PLMN has priority in a predetermined pattern as in LTE . &Lt; / RTI &gt;

In step 803, the UE 541 in the idle mode determines the value of the 5G status indication parameter while camping on a specific cell, and transfers information on the determined value from the AS to the NAS.

In step 805, the UE 541 selects the CN. For example, the UE 541 may select CN based on at least one of the values of the PLMN, the NR configuration parameter, and the NR coverage parameter for the CN type and for each CN type. According to another embodiment, CN 700 may select CN, in which case step 805 may be omitted.

In step 807, the UE 541 and the eNB 531 perform RRC connection and RRC establishment procedures. The idle UE 541 can perform RRC connection establishment (setup) procedures in response to a request from the base station or data to be transmitted occurs. Although not shown, after the RRC connection, settings related to data transmission and reception and additional settings (e.g., settings related to carrier aggregation (CA), DC, and EN-DC) may be performed.

In step 809, the UE 541 forwards the control information associated with the CN selection to the CN 700 via the eNB 531. The control information associated with the CN selection may be referred to as a CN RE-DIRECTION REQUEST. If the terminal selects the CN in step 805, the control information associated with the CN selection may include information about the selected CN. Alternatively, if the CN 700 selects CN, the control information associated with the CN selection may include at least one of a CN type and a value of a PLMN, an NR configuration parameter, and a NR coverage parameter for each CN type.

In step 811, CN 700 selects CN. For example, the CN 700 may select a CN for the UE 541 based on at least one of the CN type included in the control information associated with CN selection and the value of the PLMN, NR configuration parameter, and NR coverage parameter for each CN type . If the UE 541 has determined the CN, step 811 may be omitted.

In step 813, the CN 700 sends a CN RE-DIRECTION message to the eNB 531. The CN RE-DIRECTION message may include information about the CN determined in step 811. [ The CN RE-DIRECTION message may be included in the INITIAL CONTEXT SETUP message or may include information that may be included in the INITIAL CONTEXT SETUP message.

If it is determined that the CN is to be changed, then in step 815, the eNB 531 forwards a SERVICE REQUEST message to the target CN to be changed. The service request message may be a message for requesting the MME to set up a bearer to provide a service to the terminal. The MME can determine whether to provide the service requested by the terminal.

The CN 700 including the changed MME transmits an initial context setup request message to the eNB 531 in step 817. In step 817, the CN 700 transmits the INITIAL CONTEXT SETUP REQUEST message to the eNB 531. In step 817, The initial context setup request message includes information such as QoS information to be applied when setting up a data radio bearer (DRB) and security related information (e.g., a security key and a security algorithm) to be applied to the DRB .

After the CN change is instructed, the eNB 531 sends a SecurityModeCommand message to the UE 541 in step 819 and a SecurityModeComplete message from the UE 541 in step 821. [

When the security setting is completed, in step 823, the eNB 531 transmits an RRConnectionReconfiguration message to the UE 541. [ The RRC connection re-establishment message may include configuration information of the DRB to which the user data is to be processed, and the UE 541 sets DRB setting information to the applied DRB. In step 825, the UE 541 transmits an RRC connection reconfiguration complete message to the eNB 531 .

In step 827, the eNB 531 that has completed the DRB setup with the UE 541 transmits an initial context setup complete message to the MME. In response, the MME sets up the S-GW and the S1 bearer in step 829. To configure the S1 bearer, the MME may exchange S1 bearer setup message and S1 bearer setup response message. Here, the S1 bearer is a data transmission connection established between the S-GW and the eNB 531, and can correspond to DRB on a one-to-one basis.

In step 831, the UE 541 transmits and receives data via the eNB 531 and the S-GW.

As described above, the data transmission process may include three steps of RRC connection setup, security setup, and DRB setup. The base station (eNB 531, for example) may send a RRRCConnectionReconfiguration message to provide a new configuration to the terminal (e.g., UE 541) or to add or change the configuration of the terminal.

Figure 9 illustrates the functional separation of base stations in a wireless communication system in accordance with various embodiments of the present disclosure.

Referring to FIG. 9, a base station can be divided into a central unit (CU) and a distributed unit (DU). The separation of CU and DU can be separated based on the protocol layer. For example, the CU can perform operations of a relatively higher protocol layer, and DU can perform operations of a lower protocol layer relatively. Hereinafter, the Sphere of the base station from which the CU and the DU are separated may be referred to as a &quot; CU-DU split structure &quot;.

CU 911 or CU 913 can be connected to NG CN 900. Each CU 911 or CU 913 can be connected to a plurality of DUs 921, 923, 925, 927, 929 via a wireless backhaul or wired backhaul, and can manage and operate multiple cells connected thereto. As shown in FIG. 9, by separating the functions performed by the CU and the functions performed by the DU, the facility cost and the maintenance cost of the network implementation can be effectively reduced.

10 illustrates separation of protocol functions for CU and DU in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 10, the protocol layers may include a PHY layer, a MAC layer, an RLC layer, a PDCP layer, and upper layers. The protocol layers described above can be implemented in both CU and DU. However, since this leads to many initial equipment costs and operating costs, some of the protocol layers may be implemented in the CU and others in the DU. According to various embodiments of the present disclosure, an apparatus that handles the functionality of each protocol layer is referred to as a &quot; protocol layer device &quot;, which may be implemented in hardware or software, or a combination of hardware and software. The protocol layer devices may include a PHY layer device, a MAC layer device, and an RLC layer device PDCP layer device. For convenience of description, the operations performed by a specific protocol layer device may be expressed as being performed by a specific protocol layer.

According to Option 1 of FIG. 10, the PHY layer device, the MAC layer device, the RLC layer device, and the PDCP layer devices may be implemented in the CU, and the remaining RF devices may be implemented in the DU. According to Option 2 1033, the MAC layer device, the RLC layer device, and the PDCP layer devices can be implemented in the CU, and the remaining RF devices and PHY layer devices can be implemented in the DU. According to option 3 1035, the RLC layer device and PDCP layer devices may be implemented in the CU, and the remaining RF devices, PHY layer devices, and MAC layer devices may be implemented in the DU. According to option 4 1037, a PDCP layer device may be implemented in the CU, and the remaining RF devices, PHY layer devices, MAC layer devices, and RLC layer devices may be DUs. According to option 5 1039, higher layer devices may be implemented in the CU, and the remaining RF devices, PHY layer devices, MAC layer devices, RLC layer devices, and PDCP layer devices may be implemented in the DU.

According to various embodiments of the present disclosure, when a base station is implemented in a CU-DU split structure, for a terminal connected to DU 921 and DU 923, if the DU 921 and the terminal wireless link quality is bad, The PDCP layer device implemented in the CU 911 performs retransmission and if the DU 923 and the inter-UE wireless link quality are bad, the PDCP layer device implemented in the CU 911 with the wireless link of the DU 921 can perform retransmission. Through this, a service can be provided that has no interruption to the terminal and has a small transmission delay. That is, various embodiments of the present disclosure provide a method and apparatus for a transmitting PDCP layer device to request a receiving PDCP layer device to report a PDCP status, receive a PDCP status indicator, and perform retransmission based on the received PDCP status report to provide. In addition, the retransmission function of the PDCP layer apparatus according to various embodiments of the present disclosure can solve the following problems.

Since the NR system supports a high data rate, when the PDCP PDUs are lost or delayed in a single access environment, or when the PDCP PDUs expire due to the expiration of the PDCP expiration timer, or when the two PDCP PDUs are discarded in the transmitting side, The receiving PDCP layer triggers a reordering timer and the receiving PDCP device sends all data received until the reordering timer expires to the buffer. Should be stored. This can lead to transmission delays. Also, since the terminal must store all data received while the reordering timer is running, a large amount of memory or buffer may be required for the terminal. This may result in loss of data if the memory or buffer of the terminal can no longer accommodate the data. In addition, when the timer-triggered data arrives before the PDCP reordering timer expires or the PDCP reordering timer expires, a large amount of data received while the timer is running can be transferred to the upper layer. This can result in data loss if the upper layer fails to process all of the data.

Various embodiments of the present disclosure provide methods and apparatus for PDCP status reporting. Also, various embodiments of the present disclosure suggest a PDCP header indicator, PDCP control PDU, MAC CE or RRC message that can trigger PDCP status reporting. Accordingly, the PDCP layer device of the transmitting end triggers a PDCP status report to the PDCP layer device of the receiving end, and the receiving end configures and transmits the PDCP status report to the transmitting end. The transmitting end receives the PDCP status report to confirm the PDCP status report, (PDCP PDU or PDCP SDU, for example) successfully received according to the PDCP status report, and can perform prompt retransmission on data not successfully received. Thus, the various embodiments of the present disclosure enable to solve the transmission delay problem and the data loss problem due to the reordering timer at the receiving end.

According to various embodiments of the present disclosure, when the transmitting end receives the PDCP status report, it can discard the successfully received data according to the PDCP status report and perform a fast retransmission on the data not successfully received.

FIG. 11 shows a signal flow diagram for performing a setup for PDCP status reporting in a wireless communication system in accordance with various embodiments of the present disclosure. 11, when a UE (e.g., UE 331) switches from an RRC idle mode or an RRC inactive mode or a lightly-connected mode to an RRC connected mode, The procedure for setting is explained. In addition, a procedure for performing the setting related to the PDCP status report will be described.

Referring to FIG. 11, in step 1101, the gNB 321 transmits an RRConnectionRelease message to the UE 331. For example, the gNB 321 may send an RRCConnectionRelease message to the UE 331 to cause the UE 331 to transition to the RRC idle mode if the UE 331 in the RRC connected mode does not transmit or receive data for a predetermined reason or for a certain period of time . When data to be transmitted by the UE 331 in the idle mode occurs, the UE 331 can perform RRC Connection establishment with the gNB 321. If the UE 331 is in the RRC deactivation mode, the UE 331 may transmit an RRConnectionResumeRequest message to the gNB 321 to perform the RRC connection resumption procedure.

In step 1103, the UE 331 transmits an RRC Connection Request message to the gNB 321. For example, UE 331 may perform random access to establish uplink synchronization with gNB 321, and may transmit an RRCConnectionRequest message to gNB 321. The RRCConnectionRequest message may include an identifier of the UE (e.g. UE 331) and information about the reason for establishing a connection (establishmentCause).

In step 1105, the gNB 321 transmits an RRC Connection Setup message to the UE 331 so that the UE 331 establishes an RRC connection. The RRC connection establishment message includes a function of requesting PDCP status report or PDCP status report (hereinafter referred to as PDCP polling) for each logical channel (logical channel configuration), each bearer or each PDCP layer device (PDCP-config) And information indicating whether to use the service (for example, an indicator called pdcpPollenabled). According to various embodiments of the present disclosure, information indicating whether to use PDCP polling may be briefly referred to as a &quot; PDCP polling indicator &quot;.

The PDCP polling indicator may include at least one of an indicator for requesting a PDCP status report and an indicator for requesting an interruption of a PDCP status report. More specifically, the PDCP polling indicator may indicate whether to use PDCP polling for each logical channel, a particular IP flow of each PDCP device (or service data adaptation protocol (SDAP) device), or for a particular QoS flow . When PDCP polling is configured, the UE 331 may receive an indication to request a PDCP status report via a 1-bit indicator of the PDCP header, a PDCP control PDU, a MAC CE or an RRC message. Accordingly, the UE 331 can trigger and configure the PDCP status report. According to various embodiments of the present disclosure, the PDCP polling indicator may be sent via a different message than the RRC connection establishment message.

In addition, the RRC connection establishment message may include RRC connection configuration information. The RRC connection may be referred to as a signaling radio bearer (SRB) and may be used for the transmission and reception of RRC messages between UE 331 and gNB 321.

In step 1107, the UE 331 transmits an RRConnectionSetupComplete message to the gNB 321. [ If the gNB 321 does not know the capability of the UE 331 that is currently establishing a connection, or if it wants to know its capabilities, the gNB 321 may send a message (e.g., UECapabilityEquiry) requesting the capability information of the UE 331 , The UE 331 may send a message to the gNB 321 reporting information (e.g., UECapabilityInformation) about the capabilities of the UE 331. A message reporting information about the capabilities of the UE 331 may include an indicator indicating whether the UE 331 can use or support the PDCP status report. The RRC connection setup complete message indicates that the UE 331 sends a bearer setup for a particular service to a node 1140 that includes at least one of an MME, an Access and Mobility Management Function (AMF), a user plane function (UPF), and a session management function (E.g., a SERVICE REQUEST).

In step 1109, the gNB 321 sends a SERVICE REQUEST message to the node 1140. In response, the MME may determine whether to provide the requested service by the UE 331. [

If the MME determines to provide the service requested by the terminal, the node 1140 transmits an INITIAL CONTEXT SETUP REQUEST message to the gNB 321 in step 1111. The initial context setup request message includes information such as QoS information to be applied when setting up a data radio bearer (DRB) and security related information (e.g., a security key and a security algorithm) to be applied to the DRB .

In step 1113, the gNB 321 transmits a SecurityModeCommand message to the UE 331 to establish security with the UE 331 and receives a SecurityModeComplete message from the UE 541 in step 1115. [

When the security setting is completed, in step 1117, the gNB 321 transmits an RRConnectionReconfiguration message to the UE 331. [ The RRC connection reconfiguration message may include a PDCP polling indicator for each logical channel (logicalchannelconfig), each bearer, or each PDCP layer device (PDCP-config). More specifically, the PDCP polling indicator may indicate whether to use PDCP polling for each logical channel, a particular IP flow of each PDCP device (or service data adaptation protocol (SDAP) device), or for a particular QoS flow . When PDCP polling is configured, the UE 331 may receive an indication to request a PDCP status report via a 1-bit indicator of the PDCP header, a PDCP control PDU, a MAC CE or an RRC message. Accordingly, the UE 331 can trigger and configure the PDCP status report.

The RRC connection re-establishment message may include setting information of the DRB to which the user data is to be processed, and the UE 331 sets DRB setting information of the DRB and sets an RRC connection reconfiguration completion message to the eNB 531 in step 1119 .

In step 1121, the gNB 321 that has completed the DRB setup with the UE 331 transmits an INITIAL CONTEXT SETUP COMPLETE message to the node 1140. In step 1123, the MME transmits an S1 bearer setup message To the S-GW 1160, and in step 1125, receives the S1 Bearer Setup Response message from the S-GW 1160 to set up the S-GW 1160 and the S1 bearer. Here, the S1 bearer is a data transmission connection established between the S-GW and the eNB 531, and can correspond to DRB on a one-to-one basis.

In steps 1127 and 1129, the UE 331 transmits and receives data via the gNB 321 and the S-GW 1160. As described above, the data transmission process may include three steps of RRC connection setup, security setup, and DRB setup.

In step 1131, the gNB 321 may send a RRCConnectionReconfiguration message to the UE 331 to provide a new configuration or to add or change the configuration of the UE. The RRCConnectionReconfiguration message may include a PDCP polling indicator for each logical channel (logicalchannelconfig), each bearer, or each PDCP layer device (PDCP-config). More specifically, the PDCP polling indicator may indicate whether to use PDCP polling for each logical channel, a particular IP flow of each PDCP device (or service data adaptation protocol (SDAP) device), or for a particular QoS flow . When PDCP polling is configured, the UE 331 may receive an indication to request a PDCP status report via a 1-bit indicator of the PDCP header, a PDCP control PDU, a MAC CE or an RRC message. Accordingly, the UE 331 can trigger and configure the PDCP status report.

12 illustrates a PDCP header format for applying PDCP polling in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 12, a header having a different size may be used for the PDCP header formats 1210, 1220, and 1230 1240 according to the length of the PDCP sequence number used in the PDCP layer apparatus. That is, a 2-byte header (e.g., PDCP header formats 1210 and 1230) may be used for a 12-bit PDCP serial number and a 3-byte header (e.g., PDCP header formats 1220 and 1240) may be used for a 16- .

According to various embodiments of the present disclosure, the second bit of the PDCP header may be defined as a poll bit, such as PDCP header formats 1210 and 1220. Here, the poll bit indicates a bit corresponding to the PDCP polling indicator. Therefore, when the PDCP layer device of the transmitting end desires to report the PDCP status to the receiving end, it can set the poll bit of the PDCP header to 1 to activate the PDCP polling and request the receiving end to configure and report the PDCP status report. A PDCP header with poll bits defined, such as PDCP header formats 1210 and 1220, may be used for all data bearers.

According to various embodiments of the present disclosure, only when PDCP polling is configured for a PDCP layer device or bearer by an RRC message such as the RRC connection setup message or the RRC connection reconfiguration message of FIG. 11, (E.g., PDCP header format 1230, 1240) in which a poll bit is not defined when a header (e.g., PDCP header format 1210, 122) is used and PDCP polling is not established for the PDCP layer device or bearer by the RRC message, Can be used. Thus, when PDCP polling is set for each PDCP layer device or bearer, the processing complexity can be reduced since the second bit of the PDCP header may not be interpreted for the PDCP layer device or bearer for which PDCP polling is not set. In addition, data with a header in which a poll bit is set in the PDCP layer device or the bearer for which PDCP polling is not set may be erroneous and discarded.

According to various embodiments of the present disclosure, the PDCP polling indicator may correspond to one bit in the PDCP header, but this is exemplary and a new PDCP control PDU or MAC CE may be defined that includes a PDCP polling indicator. In addition, a PDCP polling indicator may be defined in an RRC message such as the RRC connection setup message or the RRC connection reconfiguration message in FIG. 11, and the transmitter may request the receiver to report the PDCP status through the RRC message.

In the above example, the poll bit is defined in the second bit of the PDCP header, but this is exemplary and the position in the PDCP header where the poll bit is defined is not limited.

According to various embodiments of the present disclosure, a PDCP status report triggered by a PDCP polling, an operation of a PDCP layer apparatus on a transmitting side in association with a PDCP status report, and an operation of a PDCP layer apparatus on a receiving side will be described.

13 illustrates a format for PDCP status reporting in a wireless communication system in accordance with various embodiments of the present disclosure.

According to FIG. 13, if a 12-bit PDCP serial protection is used, format 1310 may be used for PDCP status reporting. If an 18-bit PDCP serial number is used, format 1320 may be used for PDCP status reporting. If a 32-bit PDCP serial number is used, format 1330 may be used for PDCP status reporting.

In each of the formats 1310, 1320, and 1330, the D / C field may indicate whether the PDCU PDU is PDCP user data or a PDCP control PDU. The PDU type field may indicate the type of PDCP control PDU if the PDCP PDU is a PDCP control PDU. The first missing sequence number (FMS) field may indicate the first lost PDCP sequence number. The FMC (first missing COUNT value) may indicate the first lost PDCP count value in the receive reordering window. The bitmap field may indicate successful reception of the PDCP serial number after the FMS field or FMC field, the consecutive PDCP serial number (ascending order) following the PDCP count value, or the PDCP count value. For example, each bit of the bitmap field may be set to 0 or 1 to indicate successful reception.

According to various embodiments of the present disclosure, the value of the PDU type field may be set to indicate the PDCP status report, as shown in Table 2 below.

For example, as shown in Table 2, the value of the PDCP type field may be set to '011' to indicate the PDCP status report. As another example, the value of the PDCP type field for indicating a PDCP status report may be set to one of the reserved bits 100-111.

According to various embodiments of the present disclosure, the transmitting end triggers the PDCP status report to request the receiving end to report the PDCP status, and transmits data not successfully transmitted (PDCP PDU or PDCP SDU) based on the received PDCP status report A fast retransmission can be performed.

According to various embodiments of the present disclosure, the PDCP status report may be triggered by the receiving end. For example, the receiving end may trigger a PDCP status report if at least one of the following cases occurs:

- The timer set in the RRC message has expired.

- Upon receiving an instruction to request the PDCP status report from the received RRC message

- When data with the poll bit indicator set in the PDCP header is received

- When receiving a PDCP control PDU indicating PDCP status report

- MAC indicating the PDCP status report

When the MAC layer device receives a MAC CE indicating a PDCP status report request,

Here, the RRC message may include an RRC connection establishment message and / or an RRC connection reconfiguration message.

According to various embodiments of the present disclosure, the transmitting end may send an RRC message, or may trigger a PDCP status report to the receiving end via an indicator of the MAC CE, PDCP header or PDCP control PDU, and the triggering method is as follows:

- Define a new timer and periodically send a PDCP status report to the receiving end via the RRC message, MAC CE or PDCP control PDU whenever the timer expires.

- Define a new timer and periodically send a PDCP status report to the receiving end via a 1-bit indicator (eg PDCP poll bit) of the PDCP header whenever the timer expires.

- Determine whether the transmitting end requests the PDCP status report and request the PDCP status report to the receiving end via the RRC message, MAC CE or PDCP control PDU.

- Determine whether the transmitting end requests the PDCP status report and request the receiving end via the 1 bit indicator (e.g., PDCP poll bit) of the PDCP header.

In the above example, the new timer may be a timer for PDCP status reporting and may be defined, for example, as a t-StatusReportType3 timer.

According to various embodiments of the present disclosure, when the PDCP status report is triggered, the PDCP layer device of the receiving or receiving end may perform the following operations:

When a PDCP status report is triggered at the receiving end by at least one of the triggering conditions, the receiving end receives a PDCP sequence number triggering the PDCP reordering timer among the PDCP receiving window parameters or a PDCP sequence number that is smaller than the RX_REORD variable value indicating the PDCP COUNT value 1320, 1330, and 1330 of the PDCP COUNT values (i.e., the PDCP sequence number or the PDCP COUNT value included in the PDCP receiving window) A D / C field, a PDU type field, an FMC field, an FMS field, or a bitmap field based on at least one of the PDCP status report and the PDCP status report to generate a PDCP status report and transmit the generated PDCP status report to the transmitting end.

As another example, when the PDCP status report is triggered at the receiving end by at least one of the triggering conditions, the receiving end receives the RCP_NEXT variable value indicating the next PDCP sequence number or PDCP COUNT value among the PDCP receiving window parameters (I.e., the PDCP sequence number or the PDCP COUNT value included in the PDCP receiving window) and the data that has not been successfully received, and transmits the formats 1310, A PDU type field, an FMC field, an FMS field, or a bitmap field based on at least one of the PDCP status report, the PDCP status report, the PDCP status report, and the PDCP status report.

In another example, when a PDCP status report is triggered at a receiving end by at least one of the triggering conditions, the receiving end receives RX_DELIV indicating a first PDCP sequence number or a PDCP COUNT value not yet transmitted to an upper layer among PDCP receiving window parameters (I.e., a PDCP serial number or a PDCP COUNT value included in the PDCP receiving window) greater than or equal to the variable value, or data that is not successfully received, A PDCP status report is generated by configuring a D / C field, a PDU type field, an FMC fill field, an FMS field, or a bit map field based on at least one of the formats 1310, 1320, and 1330 and transmits the generated PDCP status report to the transmitting end can do.

According to various embodiments of the present disclosure, when a PDCP status report is received, the PDCP layer device of the transmitting or transmitting end may perform the following operations:

Upon receiving the PDCP status report, the PDCP layer apparatus of the transmitting end identifies data that has not been successfully transmitted with the data (PDCP PDU or PDCP SDU) that has been successfully transmitted, and the data that has been successfully transmitted is transmitted It can discard it from the buffer and perform retransmission in the buffer of the transmitting end for data that has not been successfully transmitted. That is, the transmitting end identifies data that has not been successfully transmitted in the buffer of the transmitting end, transfers the data to the lower layer, and retransmits them. In the above-described embodiments, when the PDCP layer device performs retransmission, the PDCP layer device performs fast transmission (fast delivery or expeditete) in order to allow the lower layer device to perform transmission first on data to be retransmitted in the PDCP layer device delivery to the lower layer. When the lower layer apparatus receives such an indicator, it can know that the data received from the upper layer is data for retransmission (PDCP PDU), and the lower layer apparatus (for example, the RLC layer apparatus) preferentially transmits data for retransmission Lt; / RTI &gt;

As another example, when the PDCP layer apparatus of the transmitting end receives the PDCP status report, it identifies the data that has not been successfully transmitted with the data (PDCP PDU or PDCP SDU) successfully transmitted, The data may be discarded in the buffer of the transmitting end and retransmission may be performed in the transmitting end buffer for the data previously transmitted to the lower layer among the data that has not been successfully transmitted. That is, the transmitting end identifies data that has not been successfully transmitted in the buffer of the transmitting end, transfers the data to the lower layer, and retransmits them. In the above-described embodiments, when the PDCP layer device performs retransmission, the PDCP layer device performs fast transmission (fast delivery or expeditete) in order to allow the lower layer device to perform transmission first on data to be retransmitted in the PDCP layer device delivery to the lower layer. When the lower layer apparatus receives such an indicator, it can know that the data received from the upper layer is data for retransmission (PDCP PDU), and the lower layer apparatus (for example, the RLC layer apparatus) preferentially transmits data for retransmission Lt; / RTI &gt;

According to various embodiments of the present disclosure, the PDCP status report may include a first PDCP status report and a second PDCP status report. The first PDCP status report refers to a PDCP status report for discarding data successfully transmitted by a transmitting end and immediately performing retransmission for data not successfully transmitted as described above.

Alternatively, the second PDCP status report may discard data successfully transmitted by the transmitting end, and may not immediately perform retransmission of data that has not been successfully delivered, and may perform a PDCP device re-establishment procedure or a PDCP data recovery procedure The PDCP status report for selectively retransmitting data that has not been successfully delivered only when the PDCP status report is received.

For the first PDCP status report and the second PDCP status report, one of the formats 1310, 1320, 1330 may be used. In this case, the PDU type field value for each of the first PDCP status report and the second PDCP status report may be different.

The triggering condition and / or configuration method of the PDCP status report described above may be applied to the first PDCP status report and the second PDCP status report. Also, the first PDCP status report and the second PDCP status report can be used interchangeably.

According to various embodiments of the present disclosure, it is possible for a transmitting end to transmit a 1 bit indicator of a PDCP header, a PDCP control PDU, a MAC PDU, or a MAC PDU to a PCDP layer device or bearer for which a PDCP polling is set up by an RRC message such as an RRC connection establishment message or an RRC connection reconfiguration message. Alternatively, when the PDCP status report is requested by the RRC message, the receiving terminal may trigger the first PDCP status report to generate the first PDCP status report and transmit the generated first PDCP status report to the transmitting end. The transmitting end confirms the first PDCP status report, discards the data that has been confirmed to be successfully transmitted, and can immediately perform retransmission for data that has not been successfully transmitted.

However, for a PCDP layer device or bearer in which PDCP polling has not been set by an RRC message such as an RRC connection setup message or an RRC connection reconfiguration message, the transmitting end transmits a PDCP control PDU, a PDCP control PDU, a MAC CE or an RRC message, When the status report is requested, the receiving end triggers a second PDCP status report to generate a second PDCP status report, and transmits the generated second PDCP status report to the transmitting end. The transmitting end acknowledges the second PDCP status report, discards the successfully confirmed data, does not immediately retransmit the data that was not successfully delivered, and transmits the PDCP data recovery or PDCP layer device re- The retransmission can be performed only when it is requested.

14A shows a flow diagram of a receiving end for processing a PDCP status report in a wireless communication system in accordance with various embodiments of the present disclosure. 14A may be a base station or a terminal according to various embodiments of the present disclosure.

Referring to FIG. 14A, in step 1401, the receiver determines that a PDCP status report has been triggered in the PDCP layer.

In step 1403, the receiving end generates a PDCP status report in the PDCP layer. For example, the receiving end may generate a PDCP status report using one of the formats 1310, 1320, and 1330 of FIG.

In step 1405, the receiving end transmits the generated PDCP status report to the transmitting end.

14B shows a flow diagram of a transmitting end for processing a PDCP status report in a wireless communication system in accordance with various embodiments of the present disclosure. 14B may be a base station or a terminal according to various embodiments of the present disclosure.

Referring to FIG. 14B, in step 1407, the transmitting end receives the PDCP status report. For example, the PDCP status report can be processed at the PDCP layer device of the transmitting end.

In step 1409, the transmitting end discards the successfully transmitted data based on the PDCP status report and retransmits the data that has not been successfully transmitted. In addition, the transmitting end may transmit to the lower layer an indicator indicating that fast transmission of data for retransmission is required.

FIG. 15 illustrates discontinuous reception (DRX) and resource allocation in a wireless communication system in accordance with various embodiments of the present disclosure.

According to various examples of the present disclosure, the DRX does not monitor all PDCCHs (physical downlink control channels) in order to acquire scheduling information according to the setting of the base station in order to minimize power consumption of the UE, . The time at which the PDCCH is monitored by the terminal may be referred to as an active time, and the active time may be a time corresponding to one of the following cases.

- drx-onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL or ra-ContentionResolutionTimer are driven

- If the SR request sent to the base station is still in pending state

- If the UE fails to receive the PDCCH allocated with the cell-radio network temporary identifier (C-RNTI) from the base station after receiving the random access response (RAR) for the random access preamble not selected by the UE

Referring to FIG. 15, the UE monitors the PDCCH during an on-duration 1503 repeated every DRX cycle 1501 according to DRX. In connected mode, the DRX cycle is set to two values: long DRX (long DRX) and short DRX (short DRX). A long DRX period may be applied by default and an additional short DRX period may be applied depending on the setting of the base station. If both the long DRX period and the short DRX period are set, the UE starts a short DRX timer, monitors the PDCCH according to a short DRX period, and if there is no traffic to the UE after the short DRX timer expires, The DRX cycle is changed from a short DRX cycle to a long DRX cycle. If the scheduling information for a new packet is received on the PDCCH during the active period 1503, the UE starts the DRX inactivity timer 1505 and maintains the active state (i.e., monitoring the PDCCH) while the DRX inactivity timer 1505 is running . In addition, if the scheduling information for a new packet is received on the PDCCH during the active period 1503, the UE starts a HARQ RTT (round trip time) timer 1507. The HARQ RTT timer 1507 may be applied to prevent the UE from unnecessarily monitoring the PDCCH during HARQ RTT, and the UE does not need to perform PDCCH monitoring while the HARQ RTT timer 1507 is running. However, if the DRX inactivity timer 1505 and the HARQ RTT timer 1507 are operating at the same time, the UE performs PDCCH monitoring according to the DRX inactivity timer 1505. When the HARQ RTT timer 1507 expires, a DRX retransmission timer 1509 is initiated. While the DRX retransmission timer 1509 is in operation, the UE must perform PDCCH monitoring. While the DRX retransmission timer is running, scheduling information for HARQ retransmission may be received. When the scheduling information for HARQ retransmission is received, the UE stops the DRX retransmission timer 1509 and starts the HARQ RTT timer 1507 again. The above operations may be repeated until a packet is successfully received by the terminal.

16 illustrates a frame structure for uplink data transmission in a wireless communication system according to various embodiments of the present disclosure.

In order for the UE to transmit uplink data, the UE may receive signaling indicating uplink resource allocation from the BS and transmit data through the allocated uplink resource. The signaling for indicating uplink resource allocation can be received on the PDCCH, and the PDCCH can indicate physical uplink shared channel (PUSCH) resource information that can transmit uplink data.

According to various embodiments of the present disclosure, the UE can be configured to transmit resources without periodic PDCCH reception by setting information of the RRC layer received from the Node B periodically. The time length of a resource capable of transmitting uplink data may be expressed in OFDM symbols, slots, and subframes. In FIG. 16, for convenience of explanation, it is assumed that the time length of a resource capable of transmitting uplink data is expressed in units of slots. In other words, the terminal can transmit uplink data periodically in the slots 1601, 1609, 1613, 1617, 1619, 1621, 1623, 1625, and 1627.

When the UE transmits periodic uplink data, when it is necessary to retransmit data through an HARQ process identifier (ID) for each transmission, the UE can distinguish which data should be retransmitted. The HARQ process identifier is not a permanent value, so the same HARQ process identifier can be reused for subsequent data transmission. The HARQ process identifier may be determined according to an OFDM symbol, a slot, and a subframe identifier at a time when the UE transmits uplink data. For example, the HARQ process identifier may be determined by Equation (1) below:

Here, numberOfConfGrant-Processes denotes the number of uplink processes set in the UE by the BS.

16, slots 1601, 1617 and 1623 have the same HARQ process identifier (for example, identifier # 1), slots 1609, 1619 and 1623 have the same HARQ process identifier (for example, identifier # 2) It is assumed that the slots 1613, 1621, 1627 have the same HARQ process identifier (e.g., identifier # 3). In this case, the terminal drives a timer called configuredGrantTimer each time a new transmission is started in each process. configuredGrantTimer can be set to prevent retransmission from occurring to the process until retransmission is complete when retransmission for that process occurs. Accordingly, when the UE transmits data through the slot 1601, the UE drives configuredGrantTimer # 1 1603, and when configuredGrantTimer # 1 1603 is driven, the UE detects whether a retransmission for the HARQ process of the identifier # 1 occurs PDCCH can be monitored. When the UE receives the allocation for retransmission (i.e., PDCCH) in the slot 1605 according to the HARQ process identifier used in the slot 1601 while the UE is configuredGrantTimer # 1 1603 is being driven, the UE restarts (restarts) the configured GrantTimer # do. Since the UE is configured in the slot 1617 in which the same HARQ identifier as that in the slot 1601 is used, the UE does not perform a new transmission in the slot 1617 to complete the retransmission in the slot 1601. [ If the UE does not receive the PDCCH for retransmission for the corresponding HARQ process identifier until the configuredGrantTimer # 1 1607 expires, the UE will perform a new data transmission in the new transmission slot 1623 for the corresponding HARQ process identifier .

The comparison between the configuredGrantTimer and the DRX Retransmission Timer (or drx-RetransmissionTimerUL) is shown in Table 3 below:

If the DRX-RetransmissionTimerUL expires before the configuredGrantTimer expires, the UE should monitor the PDCCH, but does not perform PDCCH monitoring because drx-RetransmissionTimerUL has expired. Accordingly, in various embodiments of the present disclosure, if DRX and periodic uplink scheduling grants are simultaneously established for the UE, the UE monitors the PDCCH as well as the DRX active time while the configuredGrantTimer timer is running. Alternatively, if drx-RetransmissionTimerUL is interrupted or expired, the terminal stops configuredGrantTimer and no longer monitors the PDCCH. At this time, since the base station knows when the UE stops the configuredGrantTimer, the UE must allocate a retransmission to the UE before stopping the configuredGrantTimer.

Also, if drx-RetransmissionTimerUL expires after the configuredGrantTimer expires, the retransmission is not performed after the configuredGrantTimer has expired, but the terminal may unnecessarily monitor the PDCCH until drx-RetransmissionTimerUL expires. In order to prevent this, when DRX and periodic uplink scheduling grant are simultaneously set for the UE, the UE stops drx-RetransmissionTimerUL when configuredGrantTimer expires, and may not unnecessarily monitor the PDCCH.

17 shows a flow diagram of a UE for DRX and periodic uplink transmissions in a wireless communication system in accordance with various embodiments of the present disclosure. FIG. 17 illustrates a method of operation of UE 141. In FIG. 17, it is assumed that the terminal is in a connection state (RRC_CONNECTED state).

Referring to FIG. 17, in step 1701, the UE receives configuration information related to DRX configuration and uplink transmission from a base station through a message of the RRC layer. Here, the message of the RRC layer may be an RRC connection reconfiguration message (RRConnectionReconfiguration). DRX refers to a technique for adjusting the time for monitoring the PDCCH to reduce power consumption of the UE. The setup information related to uplink transmission is information for periodically transmitting uplink data without PDCCH. According to various embodiments of the present disclosure, transmitting information periodically with uplink data without a PDCCH may be referred to as grant-free transmission. For example, transmission of periodic uplink data may be activated upon receipt of an RRC message (Type 1). As another example, transmission of periodic uplink data may be established by receipt of an RRC message, and may be enabled or disabled by the PDCCH. According to various embodiments of the present disclosure, information regarding DRX configuration and configuration information related to uplink transmission may be conveyed in the same RRC message, but may be conveyed through different RRC messages.

In step 1703, the UE can receive an activation command for the uplink transmission through the PDCCH. Accordingly, the UE can periodically transmit uplink data. However, if the transmission of the periodic uplink data is activated by the RRC message (type 1), step 1703 may be omitted. Then, the UE can transmit uplink data according to the set period, and perform retransmission in response to the retransmission request.

In step 1705, the UE starts (or restarts) configuredGrantTimer when the uplink data is transmitted or retransmitted.

In step 1707, the UE determines whether configuredGrantTimer is in operation.

If configuredGrantTimer is active, in step 1709, the terminal monitors the PDCCH. That is, since a retransmission request may be generated from the base station, the UE can monitor the PDCCH as in the DRX active time.

If configuredGrantTimer is not in operation, in step 1711, the UE determines whether drx-RetransmissionTimerUL for the corresponding HARQ process is in operation.

If DRX-RetransmissionTimerUL for the corresponding HARQ process is not in operation, the UE determines in step 1715 that it can not perform PDCCH monitoring for retransmission. Thereafter, when a period for a new transmission comes, the terminal returns to step 1705 and repeats the operation thereafter.

If drx-RetransmissionTimerUL for the corresponding HARQ process is active, the UE stops the drx-RetransmissionTimerUL timer in step 1713. That is, if the configuredGrantTimer is not activated, the UE can determine that retransmission for the corresponding HARQ process no longer occurs. Therefore, if the DRX-RetransmissionTimerUL is in operation, the UE transmits a DRX-RetransmissionTimerUL timer to prevent unnecessary PDCCH monitoring It can be stopped.

In step 1715, the UE determines that it can not perform PDCCH monitoring for retransmission. Thereafter, when a period for a new transmission comes, the terminal returns to step 1705 and repeats the operation thereafter.

18 shows a configuration of a base station in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in Fig. 18 can be understood as a configuration of any one of eNB 131, 133, 135, or 137, or NR NB 321, eNB 323, eNB 531, or gNB 533. Hereinafter, terms such as 'to' and 'to' denote units for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

Referring to FIG. 18, the base station includes a wireless communication unit 1810, a backhaul communication unit 1820, a storage unit 1830, and a control unit 1840.

The wireless communication unit 1810 performs functions for transmitting and receiving signals through a wireless channel. For example, the wireless communication unit 1810 performs conversion between a baseband signal and a bit string according to a physical layer specification of the system. For example, when transmitting data, the wireless communication unit 1810 generates complex symbols by encoding and modulating transmission bit streams. Also, upon receiving the data, the wireless communication unit 1810 demodulates and decodes the baseband signal to recover the received bit stream.

In addition, the wireless communication unit 1810 up-converts the baseband signal to an RF (radio frequency) band signal, transmits the signal through an antenna, and downconverts the RF band signal received through the antenna to a baseband signal. For this purpose, the wireless communication unit 1810 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC) In addition, the wireless communication unit 1810 may include a plurality of transmission / reception paths. Further, the wireless communication unit 1810 may include at least one antenna array composed of a plurality of antenna elements.

In terms of hardware, the wireless communication unit 1810 may be composed of a digital unit and an analog unit. The analog unit may include a plurality of sub-units according to operating power, an operating frequency, . The digital unit may be implemented with at least one processor (e.g., a digital signal processor (DSP)).

The wireless communication unit 1810 transmits and receives signals as described above. Accordingly, all or a part of the wireless communication unit 1810 may be referred to as a 'transmitter', a 'receiver', or a 'transceiver'. In the following description, the transmission and reception performed through the wireless channel are used to mean that the processing as described above is performed by the wireless communication unit 1810. [

The backhaul communication unit 1820 provides an interface for performing communication with other nodes in the network. That is, the backhaul communication unit 1820 converts a bit string transmitted from the base station to another node, for example, another access node, another base station, an upper node, a core network, etc., into a physical signal, .

The storage unit 1830 stores data such as a basic program, an application program, and setting information for operation of the base station. The storage unit 1830 may be composed of a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The storage unit 1830 provides the stored data at the request of the control unit 1840.

The control unit 1840 controls the overall operations of the base station. For example, the control unit 1840 transmits and receives signals through the wireless communication unit 1810 or through the backhaul communication unit 1820. In addition, the control unit 1840 records and reads data in the storage unit 1830. The controller 1840 may perform functions of a protocol stack required by the communication standard. According to another implementation, the protocol stack may be included in the wireless communication portion 1810. To this end, the control unit 1840 may include at least one processor.

According to various embodiments, the controller 1840 configures a message for requesting a packet data convergence protocol (PDCP) status report, transmits the message to the receiving end, and receives PDCP data for retransmission of PDCP data To receive a status report. In addition, the controller 1840 receives a message for requesting a packet data convergence protocol (PDCP) status report from the transmitting end and controls the receiving end to receive a PDCP status report for retransmission of the PDCP data to the transmitting end . For example, the control unit 1840 may control the base station to perform operations according to the various embodiments described above.

19 shows a configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in FIG. 19 can be understood as a configuration of UE 141, NR UE 331, LTE UE 541, NR UE 1 543, NR UE 2 545. Hereinafter, terms such as 'to' and 'to' denote units for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

Referring to FIG. 19, the terminal includes a communication unit 1910, a storage unit 1920, and a control unit 1930.

The communication unit 1910 performs functions for transmitting and receiving signals through a wireless channel. For example, the communication unit 1910 performs a function of converting a baseband signal and a bit string according to a physical layer specification of the system. For example, at the time of data transmission, the communication unit 1910 generates complex symbols by encoding and modulating transmission bit streams. Also, upon receiving the data, the communication unit 1910 demodulates and decodes the baseband signal to recover the received bit stream. Also, the communication unit 1910 up-converts the baseband signal to an RF band signal, transmits the RF band signal through the antenna, and downconverts the RF band signal received through the antenna to a baseband signal. For example, the communication unit 1910 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

In addition, the communication unit 1910 may include a plurality of transmission / reception paths. Further, the communication unit 1910 may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit 1910 may be composed of digital circuitry and analog circuitry (e.g., RFIC (radio frequency integrated circuit)). Here, the digital circuit and the analog circuit can be implemented in one package. In addition, the communication unit 1910 may include a plurality of RF chains. Furthermore, the communication unit 1910 can perform beam forming.

The communication unit 1910 transmits and receives signals as described above. Accordingly, all or a part of the communication unit 1910 may be referred to as a 'transmission unit', a 'reception unit', or a 'transmission / reception unit'. In the following description, the transmission and reception performed through the wireless channel are used to mean that the processing as described above is performed by the communication unit 1910.

The storage unit 1920 stores data such as a basic program, an application program, and setting information for operating the terminal. The storage unit 1920 may be constituted of a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The storage unit 1920 provides the stored data at the request of the control unit 1930.

The controller 1930 controls overall operations of the terminal. For example, the control unit 1930 transmits and receives signals through the communication unit 1910. Further, the control unit 1930 records and reads data in the storage unit 1920. The control unit 1930 can perform the functions of the protocol stack required by the communication standard. To this end, control unit 1930 may include at least one processor or a microprocessor, or may be part of a processor. In addition, a part of the communication unit 1910 and the control unit 1930 may be referred to as a communication processor (CP).

According to various embodiments, the controller 1930 constructs a message for requesting a packet data convergence protocol (PDCP) status report, transmits the message to a receiving end, and receives PDCP data for retransmission of PDCP data To receive a status report. In addition, the controller 1930 receives from the transmitting end a message for requesting a packet data convergence protocol (PDCP) status report, and controls the receiving end to receive a PDCP status report for retransmission of PDCP data to the transmitting end . For example, the control unit 1930 can control the terminal to perform operations according to the various embodiments described above.

20 shows a configuration of a communication unit in a wireless communication system according to various embodiments of the present disclosure. 20 shows an example of a detailed configuration of the wireless communication unit 1810 or the communication unit 1910. As shown in FIG. Specifically, FIG. 20D illustrates components for performing beamforming as part of the wireless communication unit 1810 of FIG. 18 or the communication unit 1910 of FIG.

20, the wireless communication unit 1810 or the communication unit 1910 includes a coding and modulation unit 2002, a digital beamforming unit 2004, a plurality of transmission paths 2006-1 through 406-N, and an analog beamforming unit 2008. [

The encoding and modulation unit 2002 performs channel encoding. For channel encoding, at least one of a low density parity check (LDPC) code, a convolution code, and a polar code may be used. The encoding and modulation unit 2002 generates modulation symbols by performing constellation mapping.

Digital beamforming section 2004 performs beamforming on digital signals (e.g., modulation symbols). To this end, digital beamforming section 2004 multiplies the modulation symbols with the beamforming weights. Here, the beamforming weights are used to change the size and phase of the signal, and may be referred to as a 'precoding matrix', a 'precoder', or the like. The digital beamforming unit 2004 outputs digital beamformed modulation symbols to a plurality of transmission paths 2006-1 through 406-N. At this time, according to a multiple input multiple output (MIMO) transmission scheme, the modulation symbols may be multiplexed or the same modulation symbols may be provided to a plurality of transmission paths 2006-1 through 406-N.

The plurality of transmission paths 2006-1 through 406-N convert the digital beamformed digital signals into analog signals. To this end, each of the plurality of transmission paths 2006-1 through 406-N may include an inverse fast Fourier transform (IFFT) operation unit, a cyclic prefix (CP) insertion unit, a DAC, and an up conversion unit. The CP inserter is for an orthogonal frequency division multiplexing (OFDM) scheme, and can be excluded when another physical layer scheme (e.g., FBMC (filter bank multi-carrier)) is applied. That is, the plurality of transmission paths 2006-1 through 406-N provide an independent signal processing process for a plurality of streams generated through digital beamforming. However, depending on the implementation, some of the components of the plurality of transmission paths 2006-1 through 406-N may be used in common.

The analog beamforming unit 2008 performs beamforming on the analog signal. To this end, digital beamforming section 2004 multiplies the analog signals by the beamforming weights. Here, the beamforming weights are used to change the magnitude and phase of the signal.

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

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored on a computer-readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to perform the methods in accordance with the embodiments of the present disclosure or the claims of the present disclosure.

Such programs (software modules, software) may be stored in a computer readable medium such as a random access memory, a non-volatile memory including flash memory, a read only memory (ROM), an electrically erasable programmable ROM but are not limited to, electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc-ROM (CD-ROM), digital versatile discs An optical storage device, or a magnetic cassette. Or a combination of some or all of these. In addition, a plurality of constituent memories may be included.

The program may also be stored on a communication network, such as the Internet, an Intranet, a local area network (LAN), a wide area network (WAN), a communication network such as a storage area network (SAN) And can be stored in an attachable storage device that can be accessed. Such a storage device may be connected to an apparatus performing an embodiment of the present disclosure via an external port. Further, a separate storage device on the communication network may be connected to an apparatus performing the embodiments of the present disclosure.

In the specific embodiments of the present disclosure described above, the elements included in the disclosure have been expressed singular or plural, in accordance with the specific embodiments shown. It should be understood, however, that the singular or plural representations are selected appropriately according to the situations presented for the convenience of description, and the present disclosure is not limited to the singular or plural constituent elements, And may be composed of a plurality of elements even if they are expressed.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present disclosure should not be limited to the embodiments described, but should be determined by the scope of the appended claims, as well as the appended claims.

Claims (15)

1. A method of operating a transmitting end in a wireless communication system,

   Setting a message for requesting a packet data convergence protocol (PDCP) status report;

   Transmitting the message to a receiving end;

   Receiving from the receiver a PDCP status report for retransmission of PDCP data according to the message.
2. The method of claim 1, wherein the message is a PDCP PDU (Packet Data Unit)

   Wherein the setting of the message comprises adjusting at least one bit value in the header of the PDCP PDU.
3. The method of claim 1, further comprising: identifying PDCP PDUs for retransmission among a plurality of PDCP PDUs received;

   And retransmitting the identified PDUs.
4. The method of claim 3,

   Wherein the retransmission of the PDCP data is performed based on whether a PDCP data recovery procedure is performed.
5. An apparatus for a transmitting end in a wireless communication system,

   A controller for setting a message for requesting a packet data convergence protocol (PDCP) status report;

   And a transmitting and receiving unit transmitting the message to a receiving end and receiving a PDCP status report for retransmission of PDCP data according to the message from the receiving end.
6. The method of claim 5, wherein the message is a PDCP packet data unit (PDU)

   Wherein the controller adjusts at least one bit value in a header of the PDCP PDU.
7. 7. The apparatus of claim 5, wherein the controller identifies PDCP PDUs for retransmission among a plurality of PDCP PDUs received,

   And the transceiver retransmits the identified PDUs.
8. 8. The apparatus of claim 7, wherein retransmission of the PDCP data is performed based on whether a PDCP data recovery procedure is performed.
9. A method of operating a receiver in a wireless communication system,

   Receiving a message for requesting a packet data convergence protocol (PDCP) status report from a transmitting end;

   Receiving a PDCP status report for retransmission of PDCP data to the transmitter in response to receipt of the message.
10. The method of claim 9, further comprising receiving a retransmission of PDCP PDUs according to the PDCP status report.
11. An apparatus of a receiving end in a wireless communication system,

    Receiving a message for requesting a packet data convergence protocol (PDCP) status report from a transmitter, and receiving a PDCP status report for retransmission of PDCP data to the transmitter in response to receipt of the message.
12. The apparatus of claim 11, wherein the transceiver receives retransmission of PDCP PDUs according to the PDCP status report.
13. The method of claim 9 or claim 11, wherein the message is a PDCP packet data unit (PDU)

    Wherein the header of the PDCP PDU comprises a modulated bit to request the PDCP status report.
14. The method of claim 9 or claim 11, wherein the retransmission of the PDCP data is performed based on whether a PDCP data recovery procedure is performed.
15. The method of claim 1, claim 5, claim 9 or claim 11, wherein the message is delivered via a message in a radio resource control (RRC) layer.

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