Method and apparatus for driving PDCP during data decompression failure in next generation mobile communication system

Abstract

The present disclosure discloses a communication technology and system thereof for a 5G communication system that will support a higher data transmission rate than a 4G system in combination with IoT technology. Based on 5G communication technology and IoT-related technology, the present disclosure can be applied to smart services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail, safety and security-related services, etc.). The present disclosure discloses a method and apparatus for driving a PDCP layer device during data decompression failure in a next-generation mobile communication system.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for driving a PDCP layer device during data decompression failure in a next generation mobile communication system. Background Art

[0002] In order to meet the increased demand for wireless data services since the deployment of 4G communication systems, efforts have been made to develop improved 5G or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also referred to as "beyond 4G network" communication systems or "post-LTE" systems. 5G communication systems are considered to be implemented in ultra-high frequency (millimeter wave (mmWave)) bands (e.g., 60GHz bands) in order to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance in ultra-high frequency bands, beamforming, massive multiple-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technology are discussed in 5G communication systems. In addition, in the 5G communication system, development of system network improvements is being carried out based on advanced small cells, cloud radio access network (cloudRAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, mobile network, cooperative communication, coordinated multi-point (CoMP), interference cancellation, etc. In the 5G system, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM) schemes are also developed, as well as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies.

[0003] The Internet, a human-centered connected network in which humans generate and consume information, is now developing towards the Internet of Things (IoT), in which distributed entities (such as things) exchange and process information without human intervention. The Internet of Everything (IoE) has emerged through the combination of IoT technology and big data processing technology connected to cloud servers. As technical elements required to realize IoT, such as "sensing technology", "wired / wireless communication and network infrastructure", "service interface technology" and "security technology", sensor networks, machine-to-machine (M2M) communication, machine type communication (MTC), etc. have been studied recently. Such an IoT environment can provide intelligent Internet technology (IT) services to create new value for human life by collecting and analyzing data generated between connected things. Through the integration and combination between existing information technology (IT) and various industrial applications, IoT can be applied to various fields, including smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart appliances, and advanced medical services.

[0004] In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine type communications (MTC), and machine-to-machine (M2M) communications can be implemented through beamforming, MIMO, and array antennas. Cloud radio access networks (cloud RAN) as an application of the above-mentioned big data processing technology can also be considered as an example of the fusion of 5G technology and IoT technology.

[0005] In the next generation mobile communication system, the downlink can ensure more transmission resources by using high-frequency bands and using wide bandwidths. In addition, the base station can physically install and use more antennas to obtain beamforming gain and high signal strength, so that more data can be loaded on the same frequency / time resources and sent to the UE through the downlink. However, in the case of the uplink, the UE has a physically small size, and in the case of the uplink frequency, it is difficult to use high-frequency bands and wide bandwidths, so bottlenecks are more likely to occur in uplink transmission resources than in downlink transmission resources. In addition, the maximum transmit power of the UE is much smaller than the maximum transmit power of the base station, which leads to the problem of smaller coverage during uplink data transmission. Therefore, it is necessary to effectively use transmission resources by compressing uplink data.

[0006] Uplink data is compressed by performing continuous data compression based on previous data. Therefore, if data in the middle of a series of compressed data is lost, discarded, or fails to be decompressed, all data after the lost, discarded, or failed to be decompressed data experience data decompression failure.

[0007] Each time data is received from an upper layer device, a transmitting-terminal PDCP layer device may drive a PDCP discard timer for each data. If an uplink compression process has been configured, the uplink compression process may be applied to data that should undergo an uplink compression process based on the context of a transmitting UDC buffer. A checksum field may be calculated based on the context of the transmitting UDC buffer to obtain a checksum field value. An indicator may be configured to indicate whether UDC is applied and may be configured for a UDC header. Before compression is applied to data to which a compression process has been applied, a transmitting UDC buffer may be updated based on the original data. In addition, data that has undergone uplink data compression may be encrypted, a PDCP sequence number may be assigned to the data, a PDCP header may be configured, and a PDCP PDU may be generated and sent.

[0008] The receiving-terminal PDCP layer device can rearrange the received data according to the PDCP sequence number or COUNT value. Alternatively, the RLC layer device can rearrange the received data according to the RLC sequence number, and can deliver these data to the receiving-terminal PDCP layer device. The receiving-terminal PDCP layer device can then use the indicator of the UDC header to identify whether the user data compression process (uplink data compression (UDC)) has been applied for each data (e.g., PDCP PDU or PDCP SDU). Based on the checksum field of the UDC header, the receiving-terminal PDCP layer device can identify whether the context of the sending UDC buffer and the context of the current receiving UDC buffer are synchronized or the same. If, as a result of calculating the checksum field value, it is identified that the context of the sending UDC buffer and the context of the current receiving UDC buffer are not synchronized or different, a checksum failure or decompression error occurs. PDCP control data can be sent to the sending terminal to indicate that a checksum failure or decompression error has occurred.

[0009] Upon receiving the PDCP control data (feedback on checksum failure), the transmitting PDCP layer device may initialize the transmitting UDC buffer and may reapply UDC compression to new data or data that has not been sent but to which UDC compression has been applied. However, if the receiving PDCP layer device receives data that has been generated by the transmitting PDCP layer device through data processing before receiving the PDCP control data, or data that has been delivered to a lower layer device, other checksum failures or errors will occur. Alternatively, data that does not include an indicator indicating that the transmitting UDC buffer has been initialized will be discarded. As a result, transmission resources may be wasted by the above-mentioned unnecessary data transmission. Summary of the invention

[0010] Technical issues

[0011] Therefore, one aspect of the present disclosure is to propose an efficient transmitting-end PDCP layer device operation or a receiving-end PDCP layer device operation for preventing unnecessary data transmission regarding a checksum failure that may occur during a user data compression or decompression process.

[0012] Technical Solution

[0013] In order to solve the above problems, the method performed by a sending device in a wireless communication system according to an embodiment of the present disclosure may include: sending first data compressed based on uplink data compression (UDC) to a receiving device; receiving an indicator indicating a checksum failure of the decompression of the sent first data from the receiving device; initializing the UDC buffer based on the indicator; and discarding the data preprocessed before initializing the UDC buffer.

[0014] In addition, the method performed by the receiving device in the wireless communication system according to the embodiment of the present disclosure may include:

[0015] Receive first data from a transmitting device; perform decompression of the first data based on uplink data compression (UDC); in the event that a checksum failure occurs when performing the decompression, send an indicator indicating the checksum failure to the transmitting device; and initialize the UDC buffer of the receiving device based on the sending of the indicator, wherein, based on the indicator, data preprocessed by the transmitting device based on the UDC buffer is discarded, and the UDC buffer is applied to the compression of the first data.

[0016] In addition, according to an embodiment of the present disclosure, a transmitting device in a wireless communication system may include: a transceiver; and a controller, configured to: control the transceiver to send first data compressed based on uplink data compression (UDC) to a receiving device; control the transceiver to receive an indicator indicating a checksum failure of decompression of the sent first data from the receiving device; initialize the UDC buffer based on the indicator; and discard the data preprocessed before initializing the UDC buffer.

[0017] In addition, a receiving device in a wireless communication system according to an embodiment of the present disclosure may include: a transceiver; and a controller, configured to: control the transceiver to receive first data from a transmitting device; perform decompression of the first data based on uplink data compression (UDC); in the event of a checksum failure during decompression, control the transceiver to transmit an indicator indicating the checksum failure to the transmitting device; and initialize the UDC buffer of the receiving device based on the sending of the indicator, wherein, based on the indicator, data preprocessed by the transmitting device based on the UDC buffer is discarded, and the UDC buffer is applied to the compression of the first data.

[0018] Beneficial Effects

[0019] The present disclosure proposes a process, wherein when a transmitting PDCP layer device (UE or base station) in a wireless communication system transmits data through an uplink or a downlink, the data is compressed and transmitted, and a receiving PDCP layer device (base station or UE) receives and decompresses the data. More specifically, the present disclosure proposes a method for supporting a data transmission / reception process, wherein a transmitting terminal compresses and transmits data, and a receiving terminal decompresses the data, such as a method for solving a problem associated with a header format decompression failure, and a method for solving a problem associated with a discard of a PDCP discard timer in a transmitting PDCP layer device.

[0020] In addition, the method is also applicable to such a process, wherein, when the base station sends downlink data to the UE, the data is compressed and sent, and the UE receives and decompresses the compressed downlink data. As described above, the advantages of the embodiments of the present disclosure are that the transmitting terminal compresses and sends data, so that more data can be sent, and the coverage is also improved.

[0021] In addition, the present disclosure proposes an effective transmitting-end PDCP layer operation or a receiving-end PDCP layer operation for preventing unnecessary data transmission related to checksum failures that may occur during user data compression or decompression, thereby reducing unnecessary waste of transmission resources and unnecessary data processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The structure of the LTE system to which the present disclosure can be applied is shown;

[0023] Figure 2 The radio protocol structure in the LTE system to which the present disclosure can be applied is shown;

[0024] Figure 3 The structure of the next generation mobile communication system to which the present disclosure can be applied is shown;

[0025] Figure 4 The radio protocol structure of the next generation mobile communication system to which the present disclosure can be applied is shown;

[0026] Figure 5 The present disclosure shows a configuration process for determining whether a base station performs uplink data compression when a UE establishes a connection with a network;

[0027] Figure 6 The data configuration and process for performing uplink data compression proposed by the present disclosure are shown;

[0028] Figure 7 An embodiment of an uplink data compression method that can be applied according to the present disclosure is shown;

[0029] Figure 8 It shows the problem of decompression failure in the uplink data compression method described in the present disclosure;

[0030] Fig. 9 The PDCP control PDU format that can be applied to the checksum failure handling method according to the present disclosure is shown;

[0031] Fig.10 An embodiment of a method for effectively performing user data compression when configuring an SDAP layer device or configuring an SDAP header through an RRC message according to the present disclosure is shown;

[0032] Fig.11 An embodiment of effectively performing a user data compression method and processing SDAP control data when configuring an SDAP layer device or configuring an SDAP header through an RRC message according to the present disclosure is shown;

[0033] Fig.12 An Ethernet header compression method (Ethernet header compression, EthHC) proposed when configuring an SDAP header or layer device according to the present disclosure is shown;

[0034] Fig.13 The operation of the UE according to the present disclosure is shown;

[0035] Fig.14 shows the structure of a UE to which an embodiment of the present disclosure can be applied; and

[0036] Fig.15 A block diagram configuration of a TRP in a wireless communication system to which an embodiment of the present disclosure may be applied is shown. DETAILED DESCRIPTION

[0037] Hereinafter, the operating principle of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, when it is determined that the description may make the subject matter of the present disclosure unnecessarily unclear, the detailed description of the known functions or configurations incorporated herein will be omitted. The terms to be described below are defined in consideration of the functions in the present disclosure, and may differ depending on the user, the user's intention or habit. Therefore, the definition of the terms should be based on the content of the entire specification.

[0038] In describing the present disclosure below, a detailed description of known functions or configurations incorporated herein will be omitted when it is determined that the description may make the subject matter of the present disclosure unnecessarily unclear. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0039] In the following description, for the sake of convenience, terms for identifying access nodes, terms related to network entities, terms related to messages, terms related to interfaces between network entities, terms related to various identification information, etc. are illustratively used. Therefore, the present disclosure is not limited to the terms used below, and other terms related to subjects with equivalent technical meanings may be used.

[0040] In the following description, for the convenience of description, the terms and names defined in the 1st Generation Partnership Project Long Term Evolution (1gPP LTE) standard will be used to describe the present disclosure. However, the present disclosure is not limited to these terms and names, and can be applied to systems conforming to other standards in the same manner. In the present disclosure, the term "eNB" can be used interchangeably with the term "gNB". That is, a base station described as an "eNB" can indicate a "gNB".

[0041] Figure 1 The structure of an LTE system to which the present disclosure can be applied is shown.

[0042] Reference Figure 1 , the radio access network of the LTE system may include next generation base stations (referred to as evolved Node Bs, hereinafter referred to as eNBs, Node Bs or base stations) 1a-05, 1a-10, 1a-15 and 1a-20, a mobility management entity (MME) 1a-25 or a serving gateway (S-GW) 1a-30. User equipment (hereinafter referred to as UE or terminal) 1a-35 may access an external network through eNBs 1a-05 to 1a-20 or S-GW 1a-30.

[0043] exist Figure 1In the LTE system, eNB 1a-05 to 1a-20 may correspond to an existing Node B of a UMTS system. The eNB is connected to UE 1a-35 via a radio channel and performs more complex tasks than an existing Node B. In the LTE system, since all user services related to real-time services, such as voice over IP (VoIP) via Internet Protocol, are served through a shared channel, a device that performs scheduling by collecting status information (such as the buffer status, available transmit power status, and channel status of the UE) is required, and eNB 1a-05 to 1a-20 may be responsible for the scheduling of the device. One eNB controls multiple cells. For example, in order to achieve a transmission rate of 100 Mbps, the LTE system uses orthogonal frequency division multiplexing (hereinafter referred to as OFDM) as a radio access technology in a 20 MHz bandwidth. In addition, the LTE system adopts an adaptive modulation and coding (hereinafter referred to as AMC) scheme for determining a modulation scheme and a channel coding rate based on the channel status of the UE. The S-GW 1a-30 is a device for providing a data bearer, and can generate or remove a data bearer under the control of the MME 1a-25. The MME is responsible for various control functions in addition to a mobility management function for the UE, and is connected to a plurality of base stations.

[0044] Figure 2 A radio protocol structure in an LTE system to which the present disclosure can be applied is shown.

[0045] Reference Figure 2 , the radio protocols of the LTE system include packet data convergence protocol (PDCP) 1b-05 and 1b-40, radio link control (RLC) 1b-10 and 1b-35, and medium access control (MAC) 1b-15 and 1b-30 in the UE and eNB respectively. Packet data convergence protocol (PDCP) 1b-05 and 1b-40 are used to perform operations such as IP header compression / reconstruction. The main functions of PDCP are summarized as follows.

[0046] -Header compression and decompression: ROHC only

[0047] -Transmission of user data

[0048] - In-sequence delivery of upper layer PDUs during PDCP re-establishment of RLC AM

[0049] - Sequence reordering (split bearer for DC (supports RLC AM only): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

[0050] -Duplicate detection of lower layer SDUs during PDCP reestablishment of RLC AM

[0051] - For split bearers in DC, PDCP SDU is retransmitted during handover; for RLC AM, PDCP PDU is retransmitted during PDCP data recovery)

[0052] -Encryption and decryption

[0053] - Timer-based Service Data Unit (SDU) discard in uplink

[0054] Radio link control (hereinafter referred to as RLC) 1b-10 and 1b-35 may perform an ARQ operation, etc. by reconfiguring a PDCP protocol data unit (PDU) to an appropriate size. The main functions of the RLC are summarized as follows.

[0055] -Transmission of upper layer PDU

[0056] -ARQ function (error correction through ARQ (only for AM data transmission)) -RLC SDU concatenation, segmentation and reassembly (only for UM and AM data transmission)

[0057] - Re-segmentation of RLC data PDU (only for AM data transmission)

[0058] - Reordering of RLC data PDUs (only for UM and AM data transmission)

[0059] - Duplicate detection (for UM and AM data transmission only)

[0060] -Protocol error detection (for AM data transmission only)

[0061] -RLC SDU discard (only for UM and AM data transmission)

[0062] -RLC reconstruction

[0063] MAC 1b-15 and 1b-30 are connected to multiple RLC layer devices configured in one UE, and can perform operations of multiplexing RLC PDU to MAC PDU and demultiplexing RLC PDU from MAC PDU. The main functions of MAC are summarized as follows.

[0064] - Mapping between logical channels and transport channels

[0065] - Multiplex MAC SDUs belonging to one or different logical channels into transport blocks (TBs) on the transport channel and deliver them to the physical layer / demultiplex MAC SDUs belonging to one or different logical channels from the transport channel to the transport block (TB) on the physical layer

[0066] -Dispatch information report

[0067] - Error correction through HARQ

[0068] - Priority handling between logical channels of a UE

[0069] - Prioritization between UEs through dynamic scheduling

[0070] -Multimedia broadcast and multicast service (MBMS) identifier

[0071] -Transmission format selection

[0072] -filling

[0073] The physical layers 1b-20 and 1b-25 may perform operations of channel coding and modulating upper layer data, forming the upper layer data into OFDM symbols, sending the OFDM symbols through a radio channel, or demodulating OFDM symbols received through a radio channel, channel decoding the OFDM symbols, and sending the OFDM symbols to an upper layer.

[0074] Figure 3 The structure of a next-generation mobile communication system to which the present disclosure can be applied is shown.

[0075] Reference Figure 3 , the radio access network of the next generation mobile communication system (hereinafter referred to as NR or 5G) may include a new radio node B (hereinafter referred to as NR gNB or NR base station) 1c-10 and a new radio core network (NR CN) 1c-05. User equipment (new radio user equipment, hereinafter referred to as NR UE or terminal) 1c-15 may access an external network via the NR gNB 1c-10 and the NR CN 1c-05.

[0076] exist Figure 3In the present invention, NR gNB 1c-10 corresponds to the evolved Node B (eNB) of the existing LTE system. NR gNB 1c-10 is connected to NR UE 1c-15 via a radio channel and can provide excellent services compared with the existing Node B. In the next generation mobile communication system, since all types of user services are served through shared channels, a device is required for performing scheduling by collecting status information such as the buffer status of the UE, the available transmission power status, and the channel status. In addition, NR gNB 1c-10 is responsible for the scheduling of the device. One NR gNB typically controls multiple cells. In order to achieve ultra-high-speed data transmission compared with the current LTE, NR gNB can have an existing maximum bandwidth or a larger bandwidth, and can additionally adopt beamforming technology using orthogonal frequency division multiplexing (hereinafter referred to as OFDM) as a radio access technology. In addition, NR gNB adopts an adaptive modulation and coding (AMC) scheme that determines the modulation scheme and channel coding rate based on the channel state of the UE.

[0077] NR CN 1c-05 performs functions such as mobility support, bearer configuration, QoS configuration, etc. NR CN is a device responsible for various control functions in addition to the mobility management function of UE, and can be connected to multiple base stations. In addition, the next generation mobile communication system can also be operated in conjunction with the existing LTE system, and NR CN can be connected to MME 1c-25 via a network interface. MME can be connected to eNB 1c-30, that is, connected to an existing base station.

[0078] Figure 4 A radio protocol structure of a next-generation mobile communication system to which the present disclosure can be applied is shown.

[0079] Reference Figure 4 , the radio protocol of the next generation mobile communication system includes NR PDCP1d-05 and 1d-40, NR RLC 1d-10 and 1d-35, and NR MAC 1d-15 and 1d-30 in UE and NR base station respectively. The main functions of NR PDCP 1d-05 and 1d-40 may include the following functions.

[0080] -Header compression and decompression: ROHC only

[0081] -Transmission of user data

[0082] - In-sequence delivery of upper layer PDUs

[0083] - Out-of-order delivery of upper layer PDUs

[0084] -Sequence reordering (for received PDCP PDU reordering)

[0085] - Duplicate detection of lower layer SDU

[0086] -Retransmission of PDCP SDU

[0087] -Encryption and decryption

[0088] - Timer-based SDU discard in uplink

[0089] In the above, the reordering function of the NR PDCP device may include a function of sequentially reordering the PDCP PDUs received from the lower layer based on the PDCP sequence number (SN), and a function of sending data to the upper layer in the reordered sequence. Alternatively, the reordering function of the NR PDCP device may include a function of directly sending data to the upper layer regardless of the sequence, a function of reordering the sequence and recording the lost PDCP PDUs, a function of providing a status report on the lost PDCP PDUs to the transmitting side, and a function of requesting retransmission of the lost PDCP PDUs.

[0090] The main functions of NR RLC 1d-10 and 1d-35 may include some of the following functions.

[0091] -Transmission of upper layer PDU

[0092] - In-sequence delivery of upper layer PDUs

[0093] - Out-of-order delivery of upper layer PDUs

[0094] - Error correction via ARQ

[0095] - Connection, segmentation and reassembly of RLC SDU

[0096] - Re-segmentation of RLC data PDUs

[0097] - Reordering of RLC data PDUs

[0098] - Duplicate detection

[0099] -Protocol error detection

[0100] -RLC SDU discarded

[0101] -RLC reconstruction

[0102] In the above, the in-sequence delivery (or ID) function of the NR RLC device refers to a function of sending the RLC SDU received from the lower layer to the higher layer in sequence. When one RLC SDU is initially segmented into multiple RLC SDUs and received, the in-sequence delivery function of the NR RLC device may include: a function of reassembling and sending multiple RLC SDUs, a function of reordering the received RLC PDU based on the RLC sequence number (SN) or the PDCP sequence number (SN), a function of reordering the sequence and recording the lost RLC PDU, a function of providing a status report about the lost RLC PDU to the transmitting side, a function of requesting retransmission of the lost RLC SDU, a function of sending only the RLC SDU before the lost RLC SDU in sequence to the upper layer when there is a lost RLC SDU, a function of sending all RLC SDUs received before the start of the predetermined timer to the upper layer in sequence even if there is a lost RLC SDU, when the predetermined timer has expired, or a function of sending all RLC SDUs received so far in sequence to the upper layer when the predetermined timer has expired even if there is a lost RLC SDU. In addition, in the above, the RLC PDU may be processed in the order in which the RLC PDUs are received (sequence number, regardless of the order of the sequence number, or in the order of arrival), and may be sent to the PDCP device in an out-of-order delivery manner. The function may include receiving segments stored in a buffer or segments to be received later, reconfiguring the segments in a complete RLC PDU, processing the RLC PDU, and sending the RLC PDU to the PDCP device. The NR RLC layer may not include a connection function, and the connection function may be performed by the NR MAC layer, or may be replaced by a multiplexing function of the NR MAC layer.

[0103] The out-of-order delivery function of the NR RLC device may include a function of directly sending the RLC SDU received from the lower layer to the upper layer regardless of its order. When one RLC SDU is initially segmented into multiple RLC SDUs and received, the out-of-order delivery function of the RLC device may include a function of reassembling the multiple RLC SDUs and sending them, and a function of storing the RLC SN or PDCP SN of the received RLC PDU, sorting the sequence, and recording the lost RLC PDU.

[0104] NR MAC 1d-15 and 1d-30 can be connected to multiple NR RLC layer devices configured in one UE, and the main functions of NR MAC may include some of the following functions.

[0105] - Mapping between logical channels and transport channels

[0106] -Multiplexing / demultiplexing of MAC SDU

[0107] -Dispatch information report

[0108] - Error correction through HARQ

[0109] - Priority handling between logical channels of a UE

[0110] - Prioritization between UEs through dynamic scheduling

[0111] -MBMS service logo

[0112] -Transmission format selection

[0113] -filling

[0114] NR PHY layers 1d-20 and 1d-25 may perform the following operations: channel-encode and modulate upper layer data, form the upper layer data into OFDM symbols, send the OFDM symbols via a radio channel, or demodulate and channel-decode OFDM symbols received via a radio channel, and transmit the OFDM symbols to an upper layer.

[0115] The present disclosure proposes a process in which a UE compresses data during data transmission via an uplink in a wireless communication system, and a base station decompresses the compressed data, and proposes a method for supporting a data transmission / reception process in which a transmitting terminal compresses and transmits data and a receiving terminal decompresses data, such as a detailed header format and solution when a decompression failure occurs. In addition, the method proposed in the present disclosure can also be applied to a process in which a base station compresses and transmits downlink data during transmission of downlink data to a UE, and the UE receives and decompresses the compressed downlink data. As described above, in the present disclosure, a transmitting terminal compresses and transmits data, so that more data can be transmitted, and an enhancement in coverage can be expected.

[0116] The user data compression method (uplink data compression or UDC compression method) or uplink data compression method is a method of continuously performing data compression based on previous data. Therefore, if one data in the compressed data series is lost or discarded, or if the transmission decompression fails, the decompression will fail for all data after the lost or discarded data, or the data for which decompression failed.

[0117] The process of the user data compression method is performed by a transmitting terminal PDCP layer device. Specifically, the transmitting terminal PDCP layer device can drive a PDCP discard timer for each data each time the data is received from an upper layer device, and if an uplink compression process is configured, the transmitting terminal PDCP layer device can apply the uplink compression process to the data to be subjected to the uplink compression process based on the context of the transmitting UDC buffer, can calculate the checksum field based on the transmitting UDC buffer context to obtain the checksum field value, can configure an indicator indicating whether to apply UDC and configure the indicator in the UDC header, and can update the transmitting UDC buffer based on the original data before applying compression to the data to which the compression process is applied. In addition, the transmitting terminal PDCP layer device can generate a PDCP PDU by encoding the data to which uplink data compression has been performed, assigning a PDCP sequence number thereto, and configuring a PDCP header, and can transmit the PDCP PDU.

[0118] When the receiving terminal PDCP layer device rearranges the received data based on the PDCP sequence number or COUNT value, or when the RLC layer device arranges the sequence of the received data based on the RLC sequence number and transmits it to the receiving terminal PDCP layer device, the receiving terminal PDCP layer device can identify whether the user data compression process (UDC) is applied to each data (e.g., PDCP PDU or PDCP SDU) by using the indicator of the UDC header, and can identify whether the context of the sending UDC buffer is synchronized with the context of the current receiving UDC buffer, or whether the two have the same context based on the checksum field value of the UDC header. When it is identified that the context of the sending UDC buffer and the context of the current receiving UDC buffer are not synchronized or the contexts are different when calculating the checksum field value, a checksum failure or a decompression error occurs, and the receiving terminal PDCP layer device can send PDCP control data to the sending terminal to indicate that a checksum failure or a decompression error has occurred.

[0119] When PDCP control data (feedback about checksum failure) is received, the transmitting terminal PDCP layer device can initialize the transmitting terminal UDC buffer and reapply UDC compression to new data or data that has not yet been sent but has been UDC compressed. However, when the receiving terminal PDCP layer device receives data that has been previously processed and generated by the transmitting terminal PDCP layer device before the PDCP control data is received, or data that has been transmitted to the lower layer device, the data may again cause a checksum failure or generate an error, or the data that does not contain an indicator indicating that the transmitting UDC buffer has been initialized will be discarded. Therefore, due to the above-mentioned unnecessary data transmission, transmission resources may be wasted. Therefore, the present disclosure proposes an effective transmitting terminal PDCP layer device operation or a receiving terminal PDCP layer device operation for preventing unnecessary data transmission in response to a checksum failure that may occur during user data compression or decompression.

[0120] Specifically, when the uplink data compression process (UDC) is configured, the transmitting PDCP layer device may apply the uplink data compression process to the (1-1)th data (e.g., PDCP SDU) in the first data (e.g., PDCP SDU) received from the upper layer device, and may indicate that the UDC compression process has been applied thereto by using an indicator of the UDC header. In addition, the transmitting PDCP layer device may not apply the UDC process to the (1-2)th data (e.g., PDCP SDU), and may indicate that the UDC compression process has not been applied by using an indicator of the UDC header.

[0121] In the above, the (1-1) data may include general data received from an upper layer device (e.g., an application layer device). On the other hand, the (1-2) data may include data that has been compressed once in the upper layer device (e.g., an application layer device). Since the data is data that has been compressed once, the compression rate is not improved even if the UDC compression process is applied, and therefore the UDC compression process may not be applied (whether the UDC compression process is applied to the data can be configured through an RRC message).

[0122] In addition, the (1-2) data may include SDAP control data (SDAP control PDU or end marker) received from an upper layer device (e.g., an SDAP layer device), may not allow the UDC compression process to be applied to the SDAP header or SDAP control to reduce the complexity of UE implementation, and may allow the DU of the base station implemented by the central unit-distributed unit separation (CU-DU) structure to easily read the information of the SDAP header or SDAP control data.

[0123] In the above, for the data received from the upper layer device, the PDCP layer device of the transmitting terminal can apply the uplink data compression process to the (1-1) data (e.g., PDCP SDU, upper layer device data, or application layer device data) received from the upper layer device, and generate a PDCP header by using a UDC header indicator to indicate that the UDC compression process has been applied thereto, and can be processed in the same way as the (1-2) data (e.g., PDCP data PDU or PDCP PDU). However, when the SDAP header is configured in the upper SDAP layer device of the PDCP layer device, the UDC compression method is not applied to the SDAP header attached to the data.

[0124] In addition, the PDCP layer device of the transmitting terminal may not apply the UDC process to the (2-1) data received from the upper layer device (e.g., PDCP SDU, upper layer device data, or application layer device data), and generate a PDCP header by using a UDC header indicator to indicate that the UDC compression process has not been applied to it, and can be processed in the same way as the (2-2) data (e.g., PDCP data PDU or PDCP PDU).

[0125] In the above, the (2-1) data may include data of an application layer device, data of an application layer to which a compression function is applied, SDAP control data (SDAP control PDU) of an SDAP layer device, or PDCP control data (PDCP control data) generated by a PDCP layer device. In addition, when the SDAP header of the SDAP layer device is configured, the UDC compression method is not applicable to the SDAP header attached to the data.

[0126] In the above, when receiving uplink transmission resources, the UE stores the data processed as described above (e.g., PDCP data PDU, PDCP PDU, or, for example, (1-2) data or (2-2) data) for transmission, and if the PDCP layer device of the transmitting terminal (e.g., UE) receives PDCP control data indicating checksum failure, UDC decompression failure or error (feedback indicating UDC checksum failure) from the PDCP layer device of the receiving terminal, in order to effectively process the pre-generated, stored or pre-processed data (e.g., PDCP data PDU, PDCP PDU, or (1-2) data or (2-2) data), the sending PDCP layer device may perform one of the following methods or an application method based on the following methods.

[0127] -First method: If the UDC compression or decompression process is configured in the PDCP layer device of the sending terminal, and the PDCP layer device of the sending terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the PDCP layer device of the sending terminal can initialize the sending UDC buffer for user data compression (UDC compression).

[0128] Alternatively, if a UDC compression or decompression process is configured in the PDCP layer device, and the PDCP layer device of the transmitting terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the transmitting PDCP layer device may discard data for which the PDCP discard timer has not expired or pre-generated, stored or pre-processed data (e.g., PDCP PDU, PDCP data PDU, 1-2 data, or 2-2 data). Alternatively, if data (e.g., PDCP PDU, PDCP data PDU, (1-2) data, or (2-2) data) is transmitted to a lower layer device, the transmitting PDCP layer device may send a data discard indicator regarding the data (e.g., PDCP PDU, PDCP data PDU, (1-2) data, or (2-2) data) to the lower layer device (e.g., RLC layer device) so that the data is discarded.

[0129] Alternatively, in the above, when the sending terminal PDCP layer device sends a discard indicator to the lower layer device (e.g., RLC layer device), the discard indicator only for PDCP user data (PDCP data PDU) may be sent, and the discard indicator for PDCP control data may not be sent.

[0130] Alternatively, for data that has been discarded but not yet sent in the above process (e.g., PDCP PDU, PDCP data PDU, (1-2) data, or (2-2) data), the transmitting terminal PDCP layer device may apply the UDC compression method to the (1-1) data based on the transmitting UDC buffer initialized in ascending order of PDCP SN or COUNT value, regenerate the (1-2) data, and configure the PDCP sequence number (or new PDC sequence number) mapped to the (1-1) data in the PDCP header. Alternatively, the transmitting terminal PDCP layer device may perform PDCP data processing on the (2-1) data in ascending order of PDCP SN or COUNT value to regenerate the (2-2) data, and may configure the PDCP sequence number (or new PDC sequence number) mapped to the (2-1) data in the PDCP header so as not to generate a PDCP sequence number gap or to minimize it. In the above, the PDCP discard timer corresponding to the (1-1)th data or the (2-1)th data may be driven without being restarted or initialized.

[0131] -Second method: If the UDC compression or decompression process is configured in the PDCP layer device of the sending terminal, and the PDCP layer device of the sending terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the PDCP layer device of the sending terminal can initialize the sending UDC buffer for user data compression (UDC compression).

[0132] Alternatively, if a UDC compression or decompression process is configured in a PDCP layer device, and the PDCP layer device of the transmitting terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the PDCP layer device of the transmitting terminal may discard only the data for which the PDCP discard timer has not expired or the (1-2)th data (or PDCP data PDU) to which the UDC compression process is applied in the pre-generated, stored or pre-processed data. Alternatively, if the (1-2)th data (e.g., PDCP PDU or PDCP data PDU) to which the UDC compression process is applied has been transmitted to a lower layer device (e.g., RLC layer device), the PDCP layer device of the transmitting terminal may send a data discard indicator regarding the (1-2)th data (e.g., PDCP PDU or PDCP data PDU) so that the lower layer device discards the (1-2)th data to which the UDC compression process is applied.

[0133] Alternatively, in the above, when the sending terminal PDCP layer device sends a discard indicator to the lower layer device (e.g., RLC layer device), the discard indicator only for PDCP user data (PDCP data PDU) may be sent, and the discard indicator for PDCP control data may not be sent.

[0134] Alternatively, for data that has been discarded but not yet sent in the above process (e.g., PDCP PDU, PDCP data PDU, or (1-2) data), the transmitting terminal PDCP layer device can apply the UDC compression method to the (1-1) data based on the transmission UDC buffer initialized in ascending order of the PDCP SN or COUNT value, regenerate the (1-2) data, and configure the PDCP sequence number (or new PDC sequence number) mapped to the (1-1) data in the PDCP header, so that the PDCP sequence number gap is not generated or minimized. In the above, the PDCP discard timer corresponding to the (1-1) data can be driven without being restarted or initialized.

[0135] The first method or the second method proposed in the present disclosure can be applied to an LTE PDCP layer device or an NR PDCP layer device.

[0136] A lower layer device that has received a discard indicator according to the first method or the second method proposed in the present disclosure may operate as follows.

[0137] - as an RLC layer device, if the LTE RLC layer device has received an indicator indicating to discard data (e.g., PDCP user data) from the above-mentioned LTE or NR PDCP layer device,

[0138] ■If, with respect to user data (PDCP PDU, PDCP data PDU, or RLC SDU) received from an upper layer device (PDCP layer device), a part of the user data has not been mapped to RLC user data (RLC data PDU) or has not been generated as RLC user data, the LTE RLC layer device discards the user data (when an instruction to discard a specific RLC SDU is given from an upper layer (i.e., PDCP), if no segment of the RLC SDU has been mapped to the RLC data PDU, the transmitting side of the AM RLC entity or the UM RLC entity will discard the indicated RLC SDU). Therefore, if a part of the user data has been mapped to RLC user data (RLC data PDU) or has been generated as RLC user data, the LTE RLC layer device can perform data transmission without discarding the user data.

[0139] - as an RLC layer device, if the RLC layer device has received an indicator indicating to discard data (e.g., PDCP user data) from the above-mentioned LTE or NR PDCP layer device,

[0140] ■If, with respect to user data (PDCP PDU, PDCP data PDU, or RLC SDU) received from an upper layer device (PDCP layer device), the user data or part of the user data has never been transmitted or sent to a lower layer device, the NR RLC layer device discards the user data (when an instruction to discard a specific RLC SDU is given from an upper layer (i.e., PDCP), if neither the RLC SDU nor its segments are submitted to the lower layer, the transmitting side of the AM RLC entity or the UM RLC entity will discard the indicated RLC SDU). Therefore, if the user data or part of the user data has ever been transmitted or sent to a lower layer device, the NR RLC layer device can perform data transmission without discarding the user data. Therefore, unlike the LTE RLC layer device, even if the user data is generated as RLC user data, if the NR RLC layer device does not send the user data to the lower layer device, the user data can be discarded, so that more data can be discarded and unnecessary data transmission can be more effectively prevented.

[0141] When the first method or the second method proposed in the present disclosure is applied, a gap or difference may occur in the PDCP sequence number, thereby causing a transmission delay due to a reordering timer in the PDCP layer device of the receiving terminal. In order to prevent the transmission delay caused by the reordering timer of the PDCP layer device as described above, one of the following methods or the application method proposed in the present disclosure may be applied.

[0142] -Third method: In the third method, if the PDCP layer device of the receiving terminal is an NR PDCP layer device, or if the PDCP layer device of the receiving terminal has a checksum failure related to the UDC compression method, or the PDCP control data (PDCP control PDU) has been transmitted due to the checksum failure, the PDCP layer device of the receiving terminal may continuously store the data received thereafter in the buffer until receiving the identification result indicating that the FR bit as the FR bit of the UDC header is configured to 1 and thus indicates that the transmission UDC buffer is initialized. In the above, when receiving the data corresponding to the PDCP sequence number of the data in which the checksum failure has occurred, or the PDCP sequence number less than the COUNT value, or the data corresponding to the COUNT value, the PDCP layer device of the receiving terminal may identify the indicator of the UDC header and discard the data to which the UDC compression method is applied because UDC decompression of the data may occur.

[0143] As another method, by identifying the UDC header of the stored data, the data to which the UDC compression method is not applied can be first processed and transmitted to the upper layer. If the FR bit of the UDC header of the received data is configured to 1 to indicate that the data indicating that the UDC buffer is initialized, if the reordering timer is running, the reordering timer can be stopped and initialized. Alternatively, among the stored data, for data having a PDCP sequence number or COUNT value equal to or greater than the PDCP sequence number or COUNT value of the data in which the FR bit of the UDC header is configured to 1, the data can be continuously processed sequentially (for example, the UDC decompression method is applied or not applied based on the indicator of the UDC header) without a gap in the PDCP sequence number or COUNT value, and transmitted to the upper layer device.

[0144] In the above, for data having a PDCP sequence number or COUNT value that is equal to or greater than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1, if a gap in the PDCP sequence number or COUNT value is identified when the data is continuously processed sequentially without a gap in the PDCP sequence number or COUNT value, the data is processed as described above, and a variable for reordering may be updated with a current reordering variable value, or a PDCP sequence number or COUNT value of the first data that is not transmitted to an upper layer device and has a larger PDCP sequence number or COUNT value than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1. In addition, if a gap between PDCP sequence numbers or COUNT values ​​is identified, for example, if a PDCP sequence number or COUNT value that is expected to be received next is greater than the reordering variable value, a reordering timer may be started or restarted.

[0145] -Fourth method: In the fourth method, if the PDCP layer device of the receiving terminal is an LTE PDCP layer device, or if the PDCP layer device of the receiving terminal has a checksum failure related to the UDC compression method, or the PDCP control data (PDCP control PDU) has been transmitted due to the checksum failure, the PDCP layer device of the receiving terminal may discard a plurality of data received thereafter, when a PDCP sequence number of data in which a checksum failure has occurred, a PDCP sequence number greater than a COUNT value, or data corresponding to a COUNT value is received, until receiving data indicating that the identification result FR bit of the UDC header is configured as 1 and thus indicating that the transmission UDC buffer is initialized. This is because the LTE RLC layer device arranges the data in sequence and transmits the data.

[0146] As another method, by identifying the UDC header of the stored data, the data to which the UDC compression method is not applied can be first processed and transmitted to the upper layer. If the FR bit of the UDC header of the received data is configured to 1 to indicate that the data indicating that the UDC buffer is initialized is sent, if the reordering timer is running, the reordering timer can be stopped and initialized. Alternatively, among the data received thereafter or the stored data, for data having a PDCP sequence number or COUNT value equal to or greater than the PDCP sequence number or COUNT value of the data in which the FR bit of the UDC header is configured to 1, the data can be continuously processed sequentially (for example, the UDC decompression method is applied or not applied based on the indicator of the UDC header) without a gap in the PDCP sequence number or COUNT value, and transmitted to the upper layer device.

[0147] In the above, for data having a PDCP sequence number or COUNT value equal to or greater than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1, if a gap in the PDCP sequence number or COUNT value is identified when the data is continuously processed sequentially without a gap in the PDCP sequence number or COUNT value, the data is processed as described above, and the variable for reordering may be updated with the current reordering variable value, or the PDCP sequence number or COUNT value of the first data that is not transmitted to the upper layer device, or the PDCP sequence number or COUNT value of the last data that is transmitted to the upper layer and has a larger PDCP sequence number or COUNT value than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1. In addition, if a gap between PDCP sequence numbers or COUNT values ​​is identified, for example, if the PDCP sequence number or COUNT value to be received next is expected to be greater than the reordering variable value, a reordering timer may be started or restarted.

[0148] In addition, in the above content of the present disclosure, even if a UDC compression method for performing compression on the entire data (e.g., PDCP SDU) received from an upper layer device is proposed as described above, when the upper layer device is an Ethernet protocol or the upper layer device is an SDAP layer device and the upper layer device of the SDAP layer device is an Ethernet protocol, a method is also proposed in which, for the data (e.g., PDCP SDU) received by the PDCP layer device from the upper layer device, an Ethernet header compression method (EHC) is applied only to the header part of the upper layer device corresponding to the Ethernet header.

[0149] In addition, in the above content of the present disclosure, even if a UDC compression method for performing compression on the entire data (e.g., PDCP SDU) received from an upper layer device is proposed as described above, when the upper layer device is a TCP or IP protocol or the upper layer device is an SDAP layer device and the upper layer device of the SDAP layer device is a TCP or IP protocol, a method is also proposed in which, for the data (e.g., PDCP SDU) received by the PDCP layer device from the upper layer device, the ROHC header compression method is applied only to the header part of the upper layer device corresponding to the TCP or IP header.

[0150] In addition, in the present disclosure, when the base station configures the Ethernet header compression method (or ROHC header compression method) and the UDC header compression method at the same time through the RRC message, the compression rate is not greatly improved, and it will only increase the data processing burden and complexity. Therefore, it is not necessary to configure the UDC header compression method and the Ethernet header compression method (or ROHC header compression method) at the same time. That is, the Ethernet header compression method (or ROHC header compression method) can be configured for each uplink or downlink of the PDCP layer device, and it can be configured when the UDC compression method is not configured. In addition, the UDC compression method can be configured for each uplink or downlink of the PDCP layer device, and the UDC compression method can be configured when the Ethernet header compression method (or ROHC header compression method) is not configured. However, in the above, the Ethernet header compression method and the ROHC header compression method can be configured simultaneously through the RRC message to allow the header compression process to be performed independently for the Ethernet header or the TCP / IP header, thereby greatly improving the compression rate.

[0151] In addition, since the Ethernet header compression method through the RRC message is a feedback-based method, the Ethernet header compression method cannot be applied via one direction or a unidirectional link (for example, a bearer to which an RLC UM layer device is applied and data transmission is possible only in one direction), and therefore the Ethernet header compression method cannot be configured for one direction or a unidirectional link through the RRC message, and can be configured only via a bidirectional link.

[0152] In addition, when the UDC compression method is configured via the downlink or uplink through the RRC message, it can be restricted that the out-of-order delivery function cannot be configured in the LTE RLC layer device connected to the LTE or NR PDCP layer device configured with the UDC compression method. In addition, the UDC compression method or UDC decompression method proposed in the present disclosure can be extended to the RLC UM mode, so it can be configured for the uplink or downlink.

[0153] In the above, initializing the UDC buffer may indicate initializing all values ​​of the UDC buffer to 0. As another method, when a predefined dictionary is preconfigured through an RRC message, initializing the UDC buffer may indicate inputting a predefined dictionary and initializing it to the value of the UDC buffer. The UDC compression process is reapplied using the initialized transmission UDC buffer, a UDC header is generated and configured, and then data transmission can be performed by applying a coding or integrity protection process.

[0154] In the above, the UDC header of the first data (PDCP PDU) on which data processing is performed by initializing the transmit UDC buffer and applying the UDC compression process for the first time may indicate that the transmit UDC buffer of the transmitting PDCP layer device is initialized using a 1-bit indicator, or may indicate that the receive UDC buffer of the receiving PDCP layer device is initialized. Since the receiving PDCP layer device does not know the data on which the transmit UDC buffer is initialized and UDC compression is newly performed, the transmitting PDCP layer device provides an instruction using the 1-bit indicator of the UDC buffer, and the receiving PDCP layer device may recognize the 1-bit indicator and initialize the receive UDC buffer, and may first perform the UDC decompression process on the data by using the initialized receive UDC buffer.

[0155] Therefore, if a 1-bit indicator in the UDC header of the received data (e.g., PDCP PDU) indicates that the receive UDC buffer is initialized, the receiving PDCP layer device may know that the transmit UDC buffer has been initialized and UDC compression is newly applied to the data. Therefore, the receiving PDCP layer device may initialize the receive UDC buffer and first apply the UDC decompression process to the data using the initialized receive UDC buffer.

[0156] In the present disclosure, a PDCP SDU may indicate original data received by a transmitting PDCP layer device from an upper layer device, and a PDCP PDU may indicate data that has undergone all data processing in a transmitting PDCP layer device and will then be transmitted to a lower layer device. In the above, the data processing may include processing configured in the PDCP layer device, such as integrity protection and verification, header compression, user layer data compression, or an encoding process. In addition, a PDCP PDU generated by performing data processing of a PDCP SDU is separate data from a PDCP SDU, the PDCP SDU is stored even when the PDCP PDU is discarded, and the PDCP SDU is discarded only by a PDCP data discard timer.

[0157] Figure 5 A process proposed by the present disclosure for configuring whether a base station performs uplink data compression when a UE establishes a connection with a network is shown.

[0158] Figure 5 The process of UE switching from RRC idle mode or RRC inactive mode (or lightly connected mode) to RRC connected mode and establishing a connection with the network is shown, and the process of configuring whether to perform uplink data compression (UDC) is shown.

[0159] Reference Figure 5, when a UE used to perform data transmission or reception in RRC connection mode does not perform data transmission or reception due to a predetermined reason or within a predetermined time, the base station may send an RRCConnectionRelease message to the UE to allow the UE to switch to RRC idle mode (indicated by reference numeral 1e-01). Subsequently, when data to be sent is generated, a UE that is not currently connected to it (hereinafter referred to as an idle mode UE) may perform an RRC connection establishment procedure with the base station. The UE establishes reverse transmission synchronization with the base station through a random access procedure and sends an RRCConnectionRequest message to the base station (indicated by reference numeral 1e-05). The message may include a reason for establishing a connection with the UE's identifier (establishmentCause). The base station sends an RRCConnectionSetup message so that the UE establishes an RRC connection (indicated by reference numeral 1e-10).

[0160] The message may include information indicating whether a data compression method (UDC) via an uplink is used for each logical channel (logicalchannelconfig), each bearer, or each PDCP device (PDCP configuration) or whether a data compression method via a downlink is used. In addition, more specifically, the RRCConnectionSetup message may indicate whether an uplink data compression method (UDC) is used in each logical channel, bearer, or each PDCP device (or SDAP device), only for a certain IP flow or a certain QoS flow (the base station may configure the SDAP device with information about the IP flow or QoS flow related to whether the uplink data compression method is used, so that the SDAP device can indicate to the PDCP device each QoS flow related to whether the uplink data compression method is used, or the PDCP device can identify each QoS flow for itself and determine whether to apply the uplink data compression method). In addition, if the uplink data compression method is indicated, the message may be used to indicate a predefined library to be used in the uplink data compression method, an identifier of dictionary information (dictionary), or a buffer size to be used in the uplink data compression method.

[0161] In addition, the message may include a command to establish or release uplink decompression. In addition, the above-mentioned uplink data compression method may always be configured with an RLC AM bearer (ARQ function, lossless mode with retransmission function) and may not be configured with a header compression protocol (ROHC). In addition, the RRCConnectionSetup message includes RRC connection configuration information, etc. In addition, the RRCConnectionSetup message may include RRC connection configuration information. The RRC connection is also referred to as a signaling radio bearer (SRB) and is used to send or receive an RRC message, which is a control message between a UE and a base station.

[0162] The UE that has established an RRC connection can send an RRC Connection Setup Complete message (indicated by reference numeral 1e-15) to the base station. If the base station does not know the UE capabilities of the UE that is currently establishing a connection, or if the base station wants to identify the UE capabilities, the base station can send a message to inquire about the UE capabilities. In addition, the UE can send a message reporting its own capabilities. The message reporting its own capabilities can indicate whether the UE can use uplink data compression (UDC) or can use a downlink data compression method, and can include an indicator indicating it. The RRC Connection Setup Complete message may include a control message called SERVICE REQUEST, which is a control message requested by the UE to the MME to establish a bearer for a predetermined service.

[0163] The base station sends a SERVICE REQUEST message (indicated by reference numeral 1e-20) stored in the RRCConnectionSetupComplete message to the MME, and the MME determines whether to provide the service requested by the UE. As a result of the determination, when the UE determines to provide the requested service, the MME sends an INITIAL CONTEXT SETUP REQUEST message (indicated by reference numeral 1e-25) to the base station. The INITIAL CONTEXT SETUP REQUEST message may include information such as quality of service (QoS) information to be applied in the case of configuring a data radio bearer (DRB) and security-related information (e.g., security keys and security algorithms) to be applied to the DRB. The base station may exchange SecurityModeCommand messages 1e-30 and SecurityModeComplete messages 1e-35 to establish security with the UE.

[0164] When the security configuration is completed, the base station sends an RRCConnectionReconfiguration message (indicated by reference numeral 1e-40) to the UE. The RRCConnectionReconfiguration message may include information indicating whether a data compression method (UDC) via the uplink is used for each logical channel (logicalchannelconfig), each bearer, or each PDCP device (PDCP configuration) or whether a data compression method via the downlink is used. In addition, more specifically, the RRCConnectionReconfiguration message may indicate whether an uplink data compression method (UDC) is used in each logical channel, bearer, or each PDCP device (or SDAP device), only for a certain IP flow or a certain QoS flow (the base station may configure the SDAP device with information about the IP flow or QoS flow related to whether the uplink data compression method is used, so that the SDAP device can indicate to the PDCP device each QoS flow related to whether the uplink data compression method is used, or the PDCP device can identify each QoS flow for itself and determine whether to apply the uplink data compression method).

[0165] In addition, when the uplink data compression method is indicated, the message may indicate a predefined library to be used in the uplink data compression method, an identifier of dictionary information (dictionary) or a buffer size to be used in the uplink data compression method. In addition, the message may include a command to establish or release the execution of uplink decompression. In addition, the above-mentioned uplink data compression method may always be configured with an RLC AM bearer (ARQ function, lossless mode with retransmission function), and may not be configured with a header compression protocol (ROHC).

[0166] In addition, the message includes configuration information of the DRB through which user data is processed, and the UE configures the DRB by applying the information and sends an RRCConnectionReconfigurationComplete message to the base station (indicated by reference numeral 1e-45). The base station that has completed the DRB establishment with the UE sends an INITIALCONTEXT SETUP COMPLETE message to the MME (indicated by reference numeral 1e-50), and the MME that has received the INITIAL CONTEXT SETUP COMPLETE exchanges an S1 BEARER SETUP message and an S1 BEARER SETUP RESPONSE message to configure the S1 bearer with the S-GW (indicated by reference numerals 1e-055 and 1e-60). The S1 bearer is a connection established between the S-GW and the base station for data transmission, corresponding one-to-one to the DRB.

[0167] When all the above processes are completed, the UE sends data to the base station or receives data from the base station through the S-GW (indicated by reference numerals 1e-65 and 1e-70). This general data transmission process is mainly configured by three stages: RRC connection configuration, security configuration, and DRB configuration. In addition, the base station can send an RRCConnectionReconfiguration message to newly perform, add, or change the configuration for the UE for a predetermined reason (indicated by reference numeral 1e-75).

[0168] The message may include information indicating whether a data compression method (UDC) via the uplink is used or whether a data compression method via the downlink is used for each logical channel (logicalchannelconfig), each bearer, or each PDCP device (PDCP configuration). In addition, more specifically, the RRCConnectionSetup message may indicate whether an uplink data compression method (UDC) is used in each logical channel, bearer, or each PDCP device (or SDAP device), only for a certain IP flow or a certain QoS flow (the base station may configure the SDAP device with information about the IP flow or QoS flow related to whether the uplink data compression method is used, so that the SDAP device may indicate to the PDCP device each QoS flow related to whether the uplink data compression method is used, or the PDCP device may identify each QoS flow for itself and determine whether to apply the uplink data compression method).

[0169] In addition, if it is indicated to use an uplink data compression method, the predefined library to be used in the uplink data compression method, or the identifier of the dictionary information (dictionary) or the buffer size to be used in the uplink data compression method can be indicated by the message. In addition, the RRCConnectionSetup message may include a command for establishing or releasing so as to perform uplink decompression. In addition, the above-mentioned uplink data compression method can always be configured with an RLC AM bearer (ARQ function, lossless mode with retransmission function), and may not be configured with a header compression protocol (ROHC).

[0170] In addition, when the Ethernet header compression method (or ROHC header compression method) and the uplink data compression (UDC) method are configured simultaneously through an RRC message (e.g., an RRCSetup message, an RRCResume message, or an RRCReconfiguration message), the data processing burden and complexity will increase, and the data compression rate will not be significantly improved. Therefore, in the present disclosure, the UDC compression method and the Ethernet header compression method (or ROHC header compression method) may be restricted to not be configured simultaneously. That is, the Ethernet header compression method (or ROHC header compression method) may be configured for each uplink or downlink of a PDCP layer device, and may be configured when the UDC compression method is not configured.

[0171] In addition, the UDC compression method can also be configured for each uplink or downlink of the PDCP layer device, and can be configured when the Ethernet header compression method (or ROHC header compression method) is not configured. However, in the above description, the Ethernet header compression method and the ROHC header compression method can be configured simultaneously through the RRC message to allow the header compression process to be performed independently for the Ethernet header or the TCP / IP header, thereby greatly improving the compression rate.

[0172] In addition, since the Ethernet header compression method through the RRC message is a feedback-based method, the Ethernet header compression method cannot be applied via one direction or a unidirectional link (for example, a bearer to which an RLC UM layer device is applied and data transmission is possible only in one direction), and therefore the Ethernet header compression method cannot be configured for one direction or a unidirectional link through the RRC message, and can be configured only via a bidirectional link.

[0173] In addition, when the UDC compression method is configured via the downlink or uplink through the RRC message, it can be restricted that the out-of-order delivery function cannot be configured in the LTE RLC layer device connected to the LTE or NR PDCP layer device configured with the UDC compression method. In addition, the UDC compression method or UDC decompression method proposed in the present disclosure can be extended to the RLC UM mode, so it can be configured for the uplink or downlink.

[0174] Figure 6 The data configuration and process proposed by the present disclosure for performing uplink or downlink data compression are shown.

[0175] exist Figure 6 In the PDCP layer, uplink data 1f-05 may be generated as data corresponding to services such as video transmission, photo transmission, web search, and VoLTE (HD Voice). The data generated by the application layer device may be processed by UDP or TCP / IP corresponding to the network data transmission layer, configure respective headers 1f-10 and 1f-15, and may be transmitted to the PDCP layer. When the PDCP layer receives data (PDCP SDU) from an upper layer, the PDCP layer may perform the following process.

[0176] If the uplink data compression method is configured to Figure 5 The RRC message of 1e-10, 1e-40 or 1e-75 is used in the PDCP layer. Figure 6 As shown in the figure mark 1f-20, an uplink data compression method is performed on the PDCP SDU to compress the uplink data, configure the corresponding UDC header (header for compressed uplink data) 1f-25, and perform encryption on the compressed data except the UDC header. If integrity protection is configured, integrity protection is performed, and the PDCP PDU can be configured by configuring the PDCP header 1f-30. In the above, the PDCP layer device includes a UDC compression / decompression device, determines whether to perform a UDC process on each data as configured in the RRC message, and uses the UDC compression / decompression device. The sending terminal uses the UDC compression device in the sending PDCP layer device to perform data compression, and the receiving terminal uses the UDC decompression device in the receiving PDCP layer device to perform data decompression.

[0177] Above Figure 6 The process can be applied not only when the UE performs uplink data compression, but also when the UE performs downlink data compression. In addition, the description about uplink data can be applied to downlink data in the same way.

[0178] Figure 7An embodiment of an uplink data compression method that can be applied according to the present disclosure is shown.

[0179] Figure 7 It is a view illustrating the description of the uplink data compression algorithm based on DEFLATE, and the uplink data compression algorithm based on DEFLATE is a lossless compression algorithm. The uplink data compression algorithm based on DEFLATE is basically compressed uplink data by combining LZ77 algorithm and Huffman coding. The LZ77 algorithm performs the operation of searching for the repetition array of data. When searching for the repetition array, if the repetition array is found by searching the repetition array through a sliding window, the LZ77 algorithm represents the position and overlap degree of the repetition array in the sliding window as length, to perform data compression. In the uplink data compression (UDC) method, the sliding window is also referred to as a buffer, and can be configured to 8 kilobytes or 32 kilobytes. That is, the sliding window or buffer can be compressed by recording 8192 or 32768 characters, searching for the repetition array and representing them by position and length.

[0180] Therefore, since the LZ algorithm is a sliding window method, that is, since the previously encoded data is updated in the buffer and encoding is performed again on the subsequent data, there is a correlation between the continuous data. Therefore, the encoded data must be decoded normally before the subsequent data can be decoded normally. The compressed code (expression of position, length, etc.), which is represented by position and length according to the LZ77 algorithm, is compressed again via Huffman coding.

[0181] Huffman coding searches for repeated codes again and uses short symbols for codes with a high degree of overlap and long symbols for codes with a low degree of overlap to perform compression again. Huffman coding is a prefix coding and is the best coding scheme where all codes are uniquely decodable.

[0182] As described above, the transmitting terminal performs encoding by applying the LZ77 algorithm to the original data 1g-05 (indicated by reference numeral 1g-10), updates the buffer (indicated by reference numeral 1g-15), generates a checksum bit for the content (or data) of the buffer, and configures the checksum bit in the UDC header. The checksum bit is used at the receiving end to determine whether the buffer status is valid. The code encoded with the LZ77 algorithm can be compressed again with Huffman coding and sent as uplink data (indicated by reference numeral 1g-25).

[0183] In contrast to the transmitting terminal, the receiving terminal performs a decompression process on the received compressed data. That is, the receiving terminal performs Huffman decoding (indicated by reference numeral 1g-30), updates the buffer (indicated by reference numeral 1g-35), and recognizes the validity of the updated buffer through the checksum bit of the UDC header. When it is determined that there is no error in the checksum bit, the receiving terminal may perform decoding (indicated by reference numeral 1g-40) through the LZ77 algorithm to decompress the data and reconstruct the original data, and transmit the reconstructed data to the upper layer (indicated by reference numeral 1g-45).

[0184] As described above, since the LZ algorithm is a sliding window method, that is, previously encoded data is updated in a buffer, and subsequent data is immediately encoded again, continuous data is correlated. Therefore, only if previously encoded data is decoded normally, it is possible to decode subsequent data normally. Therefore, the receiving PDCP layer device identifies the PDCP sequence number of the PDCP header and identifies the UDC header (identifies an indicator indicating whether data compression has been performed) to perform a data compression process on data to which the data compression process has been applied according to the ascending order of the PDCP sequence number.

[0185] The process proposed in the present disclosure of a base station performing uplink data compression (UDC) configuration on a UE and a process of performing uplink data compression (UDC) in the UE are given as follows.

[0186] The base station can be Figure 5 The RRC message of 1e-10, 1e-40 or 1e-75 in the RRC message is used to configure or release the UE to perform uplink data compression on the bearer or logical channel configured with the RLC AM mode. In addition, the base station can reset the UDC device (or protocol) of the PDCP layer device of the UE by using an RRC message. The reset of the UDC device (or protocol) means the reset of the UDC buffer for uplink data compression of the UE, and is performed to synchronize the UDC buffer of the UE with the UDC buffer for uplink data decompression of the base station. The reset of the buffer of the UDC device can define a new PDCP control PDU, so that the transmitting terminal (base station) resets the UDC buffer of the receiving terminal (UE), and performs synchronization of user data compression / decompression between the transmitting terminal and the receiving terminal by using the PDCP control PDU instead of the RRC message. In addition, the base station can configure whether to perform uplink data compression for each bearer, each logical channel, or each PDCP layer device by using an RRC message. More specifically, the base station may configure whether to perform uplink data decompression for each IP flow (or QoS flow) in a bearer, a logical channel, or a PDCP layer device.

[0187] In addition, the base station may configure a PDCP discard timer value for the UE through an RRC message. As the PDCP discard timer value, a PDCP discard timer value for data not subjected to uplink data compression and a PDCP discard timer value for data to which uplink data compression is applied may be configured separately.

[0188] If the UE is configured to perform uplink data compression on a predetermined bearer, logical channel, or PDCP layer device (or some QoS flows of a predetermined bearer, logical channel, or PDCP layer device) through an RRC message, the UE resets the buffer in the UDC device of the PDCP layer device according to the configuration and prepares the uplink data compression process. In addition, when the UE receives data (i.e., PDCP SDU) from an upper layer and is configured to perform uplink data compression on the PDCP layer device, the UE performs uplink data compression on the received data. If the UE is configured to perform uplink data compression only on a specific QoS flow of the PDCP layer device, the UE identifies the QoS flow identifier or the indication of the upper SDAP layer to determine whether to perform uplink data compression, and then performs uplink data compression. If the UE performs uplink data compression (UDC) and updates the buffer according to the data compression, the UE configures the UDC buffer.

[0189] In the above description, if the UE performs uplink data compression (UDC), the UE may compress the PDCP SDU received from the upper layer into UDC compressed data (UDC block) having a smaller size. The UE configures a UDC header associated with the compressed UDC compressed data. The UDC header may include an indicator indicating whether uplink data compression has been performed (for example, if the 1-bit indicator of the UDC header is 0, it means that UDC has been applied, and if the indicator is 1, it means that UDC has not been applied). In the above description, the case where the UE does not apply uplink data compression may include a case where data compression cannot be performed by the above-mentioned UDC compression method (DEFLATE algorithm) because the PDCP SDU data structure received from the upper layer is not a repeated data structure. In the above description, if the UE performs uplink data compression (UDC) on the data (PDCP SDU) received from the upper layer and updates the UDC buffer, the UE may calculate a checksum bit and include it in the UDC buffer so as to allow the receiving terminal PDCP layer device to identify the validity of the updated UDC buffer (the checksum bit has a predetermined length, for example, which can be configured as 4 bits).

[0190] In the above, the transmitting PDCP layer device may initialize the transmitting UDC buffer; and after the transmitting UDC buffer is initialized, a bit is defined and configured in the UDC header 1i-02 of the first data to which UDC compression is newly applied, to instruct the receiving PDCP layer device to initialize the receiving UDC buffer, and to newly start UDC decompression of the data configured with the UDC header 1i-02 by using the initialized receiving UDC buffer. For example, the transmitting PDCP layer device may define as follows Fig. 9 In addition, whether the transmitting PDCP layer device in which the UDC compression processing is configured as described above has applied the UDC compression processing to the data received from the upper layer can be defined by one bit, for example, the FU field 1i-10, and can be indicated by the FU field.

[0191] As described above, the UE performs ciphering on data to which uplink data decompression has been applied or not applied, performs integrity protection if integrity protection is configured, and then transfers the data to a lower layer.

[0192] Figure 8 It shows the problem of decompression failure in the uplink or downlink data compression method described in the present disclosure.

[0193] As above Figure 7 As described, the algorithm for performing uplink data compression (UDC) (DEFLATE algorithm (Huffman coding is performed after performing LZ77 algorithm)) is a scheme in which when the transmitting terminal performs data compression, the transmitting terminal updates the previously compressed data in the buffer, compares the data with the data to be compressed next based on the buffer, searches for a repeated structure, and compresses the structure by position and length. Therefore, decompression can only be successful when the receiving terminal performs decompression in the order in which the transmission has performed compression.

[0194] For example, in the case where the transmitting terminal performs UDC compression on data with PDCP sequence numbers 1, 3, 4 and 5, but does not perform UDC compression on data with PDCP sequence number 2 (as indicated by reference numeral 1h-05), the receiving terminal also needs to perform decompression on the received data in the order of PDCP sequence numbers 1, 3, 4 and 5 in the PDCP layer device in order to successfully perform decompression.

[0195] When the transmitting terminal performs UDC compression as described above, the execution is indicated by the UDC header, so the receiving terminal can also determine whether UDC compression is applied by identifying the UDC header. If the data 1h-15 corresponding to the PDCP sequence number 3 is lost in the process of performing a series of UDC decompressions as described above, the UDC decompression of the data after the data all fails. That is, UDC decompression cannot be performed on the data with PDCP sequence numbers 4 and 5 (as indicated by the figure mark 1h-10). Therefore, there should be no lost data (packets) during the uplink decompression process, and the receiving terminal needs to perform decompression in the order in which the transmitting terminal has performed UDC compression on the data. Therefore, it is necessary to run an RLC AM mode without loss and with a retransmission function.

[0196] However, the above-mentioned lost data may be caused by the PDCP discard timer of the PDCP layer device. That is, for each data (packet or PDCP SDU) received from the upper layer, the PDCP layer device drives a timer having a PDCP discard timer value configured by an RRC message. If the timer expires, the PDCP layer device discards the data corresponding to the timer. Therefore, if the timer of the data on which UDC compression has been performed expires, the data may be discarded, and thus the receiving terminal may not be able to perform UDC decompression on the UDC compressed data thereafter.

[0197] As referenced in this disclosure Figure 7 As described, according to the algorithm for performing uplink data compression (UDC) (DEFLATE algorithm (Huffman coding is performed after performing LZ77 algorithm)), when the transmitting terminal performs uplink data compression, uplink data compression is performed, and then the transmitting terminal generates a checksum by using the current buffer content, and configures the checksum in the UDC buffer. The transmitting terminal updates the buffer by using the original data of the compressed data, compares the original data with the data to be compressed next based on the buffer, searches for a repeated structure, and compresses the structure by position and length. In the above, the checksum bit in the UDC header is configured to determine the validity of the current state of the buffer before the UDC device (or function) of the PDCP layer device of the receiving terminal performs data decompression. That is, before the receiving terminal performs data decompression, the receiving terminal identifies the validity of the current receiving terminal UDC buffer through the checksum bit in the UDC header. If there is no checksum error, the receiving terminal performs data decompression, and if a checksum failure occurs, the receiving terminal does not perform data decompression, and is required to report the checksum failure to the transmitting terminal and recover from the failure.

[0198] Even when the receiving terminal performs decompression, the decompression may be successful only when the receiving terminal performs decompression in the order in which the transmission has performed compression. For example, in a case where the transmitting terminal performs UDC compression on data with PDCP sequence numbers 1, 3, 4, and 5, but does not perform UDC compression on data with PDCP sequence number 2, the receiving terminal also needs to perform decompression on the received data in the PDCP layer device in the order of PDCP sequence numbers 1, 3, 4, and 5 to successfully perform decompression. If the transmitting terminal performs UDC compression as described above, the execution is indicated by the UDC header, so the receiving terminal can also determine whether UDC compression is applied by identifying the UDC header. If a checksum failure occurs at PDCP sequence number 3 during the process of performing a series of UDC decompressions as described above, the UDC decompressions after the failure may all fail. That is, UDC decompression cannot be successfully performed on data with PDCP sequence numbers 4 and 5.

[0199] In the following description, the present disclosure proposes a checksum failure processing method for solving the above checksum failure problem.

[0200] Fig. 9 The PDCP control PDU format that can be applied to the checksum failure processing method according to the present disclosure is shown.

[0201] Reference Fig. 9 , the D / C field is used to distinguish normal data or PDCP layer control information (PDCP control PDU) in the PDCP layer, and the PDU type field is used to indicate the type of information in the above-mentioned PDCP layer control information. In the checksum failure handling method proposed in the present disclosure, a 1-bit indicator (e.g., FE field) indicating whether a checksum failure has occurred may be defined and used as a PDCP control PDU format for feedback, as shown in the figure mark 1i-01. If the value of the 1-bit indicator is 0, this may indicate that UDC decompression is being performed normally. If the value of the 1-bit indicator is 1, this may indicate that a checksum failure has occurred during UDC decompression, and indicates the initialization (reset) of the UDC buffer of the sending PDCP layer device.

[0202] To define format 1g-01, a reserved value (e.g., 011 or a random reserved value between 100 and 111) may be assigned to a PDU type to define a new PDCP control PDU, and the PDCP control PDU with the defined PDU type may be used as feedback for performing a function indicating a checksum failure.

[0203] [Table 1: PDU Type]

[0204] Bit describe 000 PDCP Status Report 001 Interspersed ROHC feedback packets 010 LWA Status Report 011 UDC checksum failure feedback 100-111 reserve

[0205] The following are examples of the present disclosure, which relate to the application Fig. 9 The checksum failure handling method of PDCP control PDU proposed in.

[0206] -If the receiving terminal (base station) recognizes that the checksum of the receiving UDC buffer for data to be released for uplink data compression (UDC) fails, the receiving terminal sends a PDCP control PDU to the UE to indicate that the checksum failure has occurred. As the PDCP control PDU, a new PDCP control PDU may be defined and used, and a new indicator may be defined and then included in an existing PDCP control PDU, whereby the existing PDCP control PDU may be modified and used. In another method, an indicator for resetting the UDC buffer due to a checksum failure may be defined instead of the PDCP sequence number, and the indicator may indicate the reset.

[0207] -Operation of the receiving terminal: If a checksum failure occurs, the receiving terminal may immediately initialize the UDC buffer. In addition, the receiving terminal rearranges the newly received data according to the PDCP sequence number, and then identifies the UDC header of each data in ascending order of the PDCP sequence number. The receiving terminal discards the data, which includes an indicator in each UDC header indicating that the UDC buffer of the transmitting terminal has been reset due to a UDC checksum failure, and does not include an indication indicating the initialization of the receiving UDC buffer, and is indicated as having performed UDC compression. In addition, the UDC header of the newly received data does not include an indicator indicating that the UDC buffer of the transmitting terminal has been reset due to a UDC checksum failure, and the data indicating that UDC compression has not been performed are all received without a gap in the middle of the PDCP sequence number, and the receiving terminal may process these data in ascending order of the PDCP sequence number, and then transmit them to an upper layer device. The receiving terminal can initialize the receiving UDC buffer from the data, and the multiple data include an indicator indicating the reset of the receiving UDC buffer and an indicator indicating that the UDC buffer of the transmitting terminal is reset due to a UDC checksum failure in each UDC header, and the receiving terminal can restart decompression of the multiple UDC compressed data in ascending order of the PDCP sequence number.

[0208] -Operation of the transmitting terminal: When receiving a PDCP control PDU, the transmitting terminal (UE) may reset (initialize) the UDC transmission buffer; if there is data (e.g., PDCP PDU) that has not yet been transmitted among the data generated by the UDC compression process, the data is discarded before initializing the UDC transmission buffer; based on the initialized transmission UDC buffer, uplink data compression (UDC) is performed again on the original data (e.g., PDCP SDU) of the data that has not yet been transmitted; the UDC buffer is updated; a checksum bit is included in the UDC header; the UDC header and data part are encoded; a PDCP header is generated; and the PDCP PDU is configured to be transmitted to a lower layer.

[0209] In addition, the transmitting terminal may transmit the UDC header or the PDCP header of the newly configured PDCP PDU after including an indicator indicating that the transmitting terminal buffer has been reset and an indication of initializing the receiving terminal buffer, and may newly allocate the PDCP sequence number that has not yet been sent in ascending order (i.e., if the COUNT value and security key that have been sent have been encoded again with the PDCP sequence number, HFN, or with the same PDCP COUNT value and security key and then resent, the risk of hacker attacks increases, so the rule that one PDCP COUNT value is allowed to be encoded and sent once may be followed).

[0210] In another method, when receiving an indication indicating that a checksum failure has occurred, the transmitting terminal may reset the transmitting UDC buffer; perform new UDC compression only for the PDCP PDU to be newly configured, or for data having a PDCP sequence number greater than or equal to the data that has not yet been transmitted from the transmitting terminal to the lower layer; and transmit the compressed data or PDCP PDU to the lower layer. In addition, after including an indicator indicating that the transmitting terminal UDC buffer has been reset (or an indicator to initialize the receiving terminal buffer), the transmitting terminal may transmit the UDC header or PDCP header of the newly configured PDCP PDU (i.e., if data that has been encoded with a PDCP COUNT value and a security key and has been transmitted is encoded again with the same PDCP COUNT value and security key and then retransmitted, the risk of hacker attacks increases, so the rule that one PDCP COUNT value allows encoding and transmission once may be followed).

[0211] In the above, the present disclosure proposes an effective transmitting terminal PDCP layer device operation or a receiving terminal PDCP layer device operation for preventing unnecessary data transmission in response to a checksum failure that may occur during user data compression or decompression.

[0212] Specifically, when the uplink data compression process (UDC) is configured, the transmitting PDCP layer device may apply the uplink data compression process to the (1-1)th data (e.g., PDCP SDU) in the first data (e.g., PDCP SDU) received from the upper layer device, and may indicate that the UDC compression process has been applied thereto by using an indicator of the UDC header. In addition, the transmitting PDCP layer device may not apply the UDC process to the (1-2)th data (e.g., PDCP SDU), and may indicate that the UDC compression process has not been applied by using an indicator of the UDC header.

[0213] In the above, the (1-1) data may include general data received from an upper layer device (e.g., an application layer device). On the other hand, the (1-2) data may include data that has been compressed once in the upper layer device (e.g., an application layer device). Since the data is data that has been compressed once, the compression rate is not improved even if the UDC compression process is applied, and therefore the UDC compression process may not be applied (whether the UDC compression process is applied to the data can be configured through an RRC message).

[0214] In addition, the (1-2) data may include SDAP control data (SDAP control PDU or end marker) received from an upper layer device (e.g., an SDAP layer device), may not allow the UDC compression process to be applied to the SDAP header or SDAP control to reduce the complexity of UE implementation, and may allow the ADU of the base station implemented by the central unit-distributed unit separation (CU-DU) structure to easily read the information of the SDAP header or SDAP control data.

[0215] In the above, for the data received from the upper layer device, the PDCP layer device of the transmitting terminal can apply the uplink data compression process to the (1-1) data (e.g., PDCP SDU, upper layer device data, or application layer device data) received from the upper layer device, and generate a PDCP header by using a UDC header indicator to indicate that the UDC compression process has been applied thereto, and can be processed in the same manner as the (1-2) data (e.g., PDCP data PDU or PDCP PDU). However, when the SDAP header is configured in the upper SDAP layer device of the PDCP layer device, the UDC compression method is not applicable to the SDAP header attached to the data.

[0216] In addition, the PDCP layer device of the transmitting terminal may not apply the UDC process to the (2-1) data (e.g., PDCP SDU, upper layer device data, or application layer device data) received from the upper layer device, and generate a PDCP header by using a UDC header indicator to indicate that the UDC compression process has not been applied to it, and may be processed in the same manner as the (2-2) data (e.g., PDCP data PDU or PDCP PDU). In the above, the (2-1) data may include data of an application layer device, data of an application layer to which a compression function is applied, SDAP control data (SDAP control PDU) of an SDAP layer device, or PDCP control data (PDCP control data) generated by a PDCP layer device. In addition, when the SDAP header of the SDAP layer device is configured, the UDC compression method is not applicable to the SDAP header attached to the data.

[0217] In the above, when uplink transmission resources are received, the UE stores the data processed as described above (e.g., PDCP data PDU, PDCP PDU, or, for example, (1-2) data or (2-2) data) for transmission, and if the PDCP layer device of the transmitting terminal (e.g., UE) receives PDCP control data indicating checksum failure, UDC decompression failure or error (feedback indicating UDC checksum failure) from the PDCP layer device of the receiving terminal, in order to effectively process the pre-generated, stored or pre-processed data (e.g., PDCP data PDU, PDCP PDU, or (1-2) data or (2-2) data), the transmitting PDCP layer device may perform one of the following methods or an application method based on the following method.

[0218] -First method: If the UDC compression or decompression process is configured in the PDCP layer device of the sending terminal, and the PDCP layer device of the sending terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the PDCP layer device of the sending terminal can initialize the sending UDC buffer for user data compression (UDC compression).

[0219] Alternatively, if a UDC compression or decompression process is configured in the PDCP layer device, and the PDCP layer device of the transmitting terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the PDCP layer device of the transmitting terminal may discard data for which the PDCP discard timer has not expired or pre-generated, stored or pre-processed data (e.g., PDCP PDU, PDCP data PDU, 1-2 data, or 2-2 data). Alternatively, if data (e.g., PDCP PDU, PDCP data PDU, (1-2) data, or (2-2) data) is transmitted to a lower layer device, the PDCP layer device of the transmitting terminal may send a data discard indicator regarding the data (e.g., PDCP PDU, PDCP data PDU, (1-2) data, or (2-2) data) to the lower layer device (e.g., RLC layer device) so that the data is discarded.

[0220] Alternatively, in the above, when the sending terminal PDCP layer device sends a discard indicator to the lower layer device (e.g., RLC layer device), the discard indicator only for PDCP user data (PDCP data PDU) may be sent, and the discard indicator for PDCP control data may not be sent.

[0221] Alternatively, for data that has been discarded but not yet sent in the above process (e.g., PDCP PDU, PDCP data PDU, (1-2)th data, or (2-2)th data), the PDCP layer device of the transmitting terminal may apply the UDC compression method to the (1-1)th data based on the transmitting UDC buffer initialized in ascending order of PDCP SN or COUNT value, regenerate the (1-2)th data, and configure the PDCP sequence number (or new PDC sequence number) mapped to the (1-1)th data in the PDCP header. Alternatively, the PDCP layer device of the transmitting terminal may perform PDCP data processing on the (2-1)th data again in ascending order of PDCP SN or COUNT value to regenerate the (2-2)th data, and may configure the PDCP sequence number (or new PDC sequence number) mapped to the (2-1)th data in the PDCP header so as not to generate a PDCP sequence number gap or to minimize it. In the above, the PDCP discard timer corresponding to the (1-1)th data or the (2-1)th data may be driven without being restarted or initialized.

[0222] - Second method: If a UDC compression or decompression process is configured in the PDCP layer device of the transmitting terminal, and the PDCP layer device of the transmitting terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the PDCP layer device of the transmitting terminal may initialize a transmitting UDC buffer for user data compression (UDC compression). Alternatively, if a UDC compression or decompression process is configured in the PDCP layer device, and the PDCP layer device of the transmitting terminal receives PDCP control data (PDCP control PDU) indicating a checksum failure from the PDCP layer device of the receiving terminal, the PDCP layer device of the transmitting terminal may discard only the (1-2)th data (or PDCP data PDU) to which the UDC compression process is applied among the pre-generated, stored or pre-processed data whose PDCP discard timer has not expired. Alternatively, if the (1-2)th data (e.g., PDCP PDU or PDCP data PDU) to which the UDC compression process is applied has been transmitted to a lower layer device (e.g., RLC layer device), the PDCP layer device of the transmitting terminal may send a data discard indicator regarding the (1-2)th data (e.g., PDCP PDU or PDCP data PDU) so that the lower layer device discards the (1-2)th data to which the UDC compression process is applied.

[0223] Alternatively, in the above, when the sending terminal PDCP layer device sends a discard indicator to the lower layer device (e.g., RLC layer device), the discard indicator only for PDCP user data (PDCP data PDU) may be sent, and the discard indicator for PDCP control data may not be sent.

[0224] Alternatively, for data that has been discarded but not yet sent in the above process (e.g., PDCP PDU, PDCP data PDU, or (1-2) data), the transmitting terminal PDCP layer device can apply the UDC compression method to the (1-1) data based on the transmission UDC buffer initialized in ascending order of the PDCP SN or COUNT value, regenerate the (1-2) data, and configure the PDCP sequence number (or new PDC sequence number) mapped to the (1-1) data in the PDCP header, so that the PDCP sequence number gap is not generated or minimized. In the above, the PDCP discard timer corresponding to the (1-1) data can be driven without being restarted or initialized.

[0225] The first method or the second method proposed in the present disclosure can be applied to an LTE PDCP layer device or an NR PDCP layer device.

[0226] A lower layer device that has received a discard indicator according to the first method or the second method proposed in the present disclosure may operate as follows.

[0227] - as an RLC layer device, if the LTE RLC layer device has received an indicator indicating to discard data (e.g., PDCP user data) from the above-mentioned LTE or NR PDCP layer device,

[0228] ■If, with respect to user data (PDCP PDU, PDCP data PDU, or RLC SDU) received from an upper layer device (PDCP layer device), a part of the user data has not been mapped to RLC user data (RLC data PDU) or has not been generated as RLC user data, the LTE RLC layer device discards the user data (when an instruction to discard a specific RLC SDU is given from an upper layer (i.e., PDCP), if no segment of the RLC SDU has been mapped to the RLC data PDU, the transmitting side of the AM RLC entity or the UM RLC entity will discard the indicated RLC SDU). Therefore, if a part of the user data has been mapped to RLC user data (RLC data PDU) or has been generated as RLC user data, the LTE RLC layer device can perform data transmission without discarding the user data.

[0229] - as an RLC layer device, if the RLC layer device has received an indicator indicating to discard data (e.g., PDCP user data) from the above-mentioned LTE or NR PDCP layer device,

[0230] ■If, with respect to user data (PDCP PDU, PDCP data PDU, or RLC SDU) received from an upper layer device (PDCP layer device), the user data or part of the user data has never been transmitted or transferred to a lower layer device, the NR RLC layer device discards the user data (when an instruction to discard a specific RLC SDU is given from an upper layer (i.e., PDCP), if neither the RLC SDU nor its segments are submitted to the lower layer, the transmitting side of the AM RLC entity or the UM RLC entity will discard the indicated RLC SDU). Therefore, if the user data or part of the user data has ever been transmitted or sent to a lower layer device, the NR RLC layer device can perform data transmission without discarding the user data. Therefore, unlike the LTE RLC layer device, even if the user data is generated as RLC user data, if the NR RLC layer device does not send the user data to the lower layer device, the user data can be discarded, so that more data can be discarded and unnecessary data transmission can be more effectively prevented.

[0231] When the first method or the second method proposed in the present disclosure is applied, a gap or difference may occur in the PDCP sequence number, thereby causing a transmission delay due to a reordering timer in the PDCP layer device of the receiving terminal. In order to prevent the transmission delay caused by the reordering timer of the PDCP layer device as described above, one of the following methods or the application method proposed in the present disclosure may be applied.

[0232] -Third method: In the third method, if the PDCP layer device of the receiving terminal is an NR PDCP layer device, or if the PDCP layer device of the receiving terminal has a checksum failure related to the UDC compression method, or the PDCP control data (PDCP control PDU) has been transmitted due to the checksum failure, the PDCP layer device of the receiving terminal may continuously store the data received thereafter in the buffer until receiving the data indicating the identification result of the FR bit as the UDC header that the FR bit is configured to 1 and thus indicates that the transmission UDC buffer is initialized. When receiving the data corresponding to the PDCP sequence number of the data in which the checksum failure has occurred, or the PDCP sequence number less than the COUNT value, or the data corresponding to the COUNT value, the PDCP layer device of the receiving terminal may identify the indicator of the UDC header and discard the data to which the UDC compression method is applied because UDC decompression of the data may occur.

[0233] As another method, by identifying the UDC header of the stored data, the data to which the UDC compression method is not applied can be first processed and transmitted to the upper layer. If the FR bit of the UDC header of the received data is configured to 1 to indicate that the data indicating that the UDC buffer is initialized, if the reordering timer is running, the reordering timer can be stopped and initialized. Alternatively, among the stored data, for data having a PDCP sequence number or COUNT value equal to or greater than the PDCP sequence number or COUNT value of the data in which the FR bit of the UDC header is configured to 1, the data can be continuously processed sequentially (for example, the UDC decompression method is applied or not applied based on the indicator of the UDC header) without a gap in the PDCP sequence number or COUNT value, and transmitted to the upper layer device. In the above, for data having a PDCP sequence number or COUNT value that is equal to or greater than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1, if a gap in the PDCP sequence number or COUNT value is identified when the data is continuously processed sequentially without a gap in the PDCP sequence number or COUNT value, the data is processed as described above, and a variable for reordering may be updated with a current reordering variable value, or a PDCP sequence number or COUNT value of first data that is not transmitted to an upper layer device and has a larger PDCP sequence number or COUNT value than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1. In addition, if a gap between PDCP sequence numbers or COUNT values ​​is identified, for example, if a PDCP sequence number or COUNT value that is expected to be received next is greater than the reordering variable value, a reordering timer may be started or restarted.

[0234] -Fourth method: In the fourth method, if the PDCP layer device of the receiving terminal is an LTE PDCP layer device, or if the PDCP layer device of the receiving terminal has a checksum failure related to the UDC compression method, or the PDCP control data (PDCP control PDU) has been sent due to the checksum failure, the PDCP layer device of the receiving terminal may discard a plurality of data received thereafter, when the PDCP sequence number of the data in which the checksum failure has occurred, the PDCP sequence number greater than the COUNT value, or the data corresponding to the COUNT value is received, until the identification result indicating that the FR bit of the UDC header is configured as 1 and thus indicates that the sending UDC buffer is initialized is received. This is because the LTE RLC layer device arranges the data in sequence and sends the data. As another method, by identifying the UDC header of the stored data, the data to which the UDC compression method is not applied can be first processed and transmitted to the upper layer. If the FR bit of the UDC header of the received data is configured as 1 to indicate the data indicating that the sending UDC buffer is initialized, if the reordering timer is running, the reordering timer can be stopped and initialized. Alternatively, among data received thereafter or data stored, for data having a PDCP sequence number or COUNT value equal to or greater than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured to be 1, the data may be processed continuously and sequentially (e.g., applying or not applying the UDC decompression method based on an indicator of the UDC header) without a gap in the PDCP sequence number or COUNT value and transmitted to an upper layer device. In the above, for data having a PDCP sequence number or COUNT value equal to or greater than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1, if a gap in the PDCP sequence number or COUNT value is identified when the data is continuously processed sequentially without a gap in the PDCP sequence number or COUNT value, the data is processed as described above, and the variable for reordering may be updated with the current reordering variable value, or the PDCP sequence number or COUNT value of the first data that is not transmitted to the upper layer device, or the PDCP sequence number or COUNT value of the last data that is transmitted to the upper layer and has a larger PDCP sequence number or COUNT value than the PDCP sequence number or COUNT value of data in which the FR bit of the UDC header is configured as 1. In addition, if a gap between PDCP sequence numbers or COUNT values ​​is identified, for example, if the PDCP sequence number or COUNT value to be received next is expected to be greater than the reordering variable value, a reordering timer may be started or restarted.

[0235] In the present disclosure, an embodiment of effectively performing a user data compression method in a case where an SDAP layer device or an SDAP header is configured by an RRC message is proposed as follows. In this embodiment, the user data compression method is not applied to the SDAP header, the SDAP header is not encoded, and the UDC header is encoded. In addition, in this embodiment, the UDC header is attached after the SDAP header, the UDC header is attached immediately before the compressed UDC block, and the SDAP header is attached before the UDC header.

[0236] According to the embodiment, through the above-mentioned features, the QoS information of the SDAP header can be utilized without the need for the sending terminal or the receiving terminal to decode the information of the SDAP header. For example, the base station can use the QoS information for scheduling. In addition, in the case of implementing the UE, it is not necessary to generate the SDAP header each time the upper layer data is received. The hardware accelerator can perform the UDC process, immediately generate the UDC and attach and perform encoding, and the SDAP header can be attached later to facilitate the implementation of the UE.

[0237] In addition, the UDC header can be encoded to enhance security. In addition, in the above-mentioned embodiment, by changing the position of the SDAP header and the position of the UDC header, when performing the user data compression process, unnecessary processes of processing after excluding the SDAP header or processing after removing the SDAP header and then reattaching the SDAP header can be reduced, and a unified process can be performed on the UDC header and the UDC data block.

[0238] Fig.10 An embodiment of a method for effectively performing user data compression in a case where an SDAP layer device or an SDAP header is configured through an RRC message according to the present disclosure is shown.

[0239] Reference Fig.10 , for example, in Figure 5In the case where the SDAP layer device or the SDAP header is configured to be used by the RRC message and user data compression (UDC) is configured, if the SDAP layer device receives data from the upper layer, the SDAP layer device can generate and configure the SDAP header, as indicated by reference numeral 1j-05, and transmit the data and the SDAP header to the PDCP layer device. The PDCP layer device can perform a user data compression process on the PDCP SDU (SDAP header and IP packet, as indicated by reference numeral 1j-06) received from the upper SDAP layer device (as indicated by reference numeral 1j-07). In addition, the PDCP layer device can calculate the checksum field and configure whether UDC has been applied to generate a UDC header and attach the UDC header (as indicated by reference numeral 1j-10) immediately before the compressed UDC data block (after the SDAP header). If integrity protection is configured, the PDCP layer device can apply integrity protection to the SDAP header, UDC header, compressed UDC block, and PDCP header before performing the encoding process, and then can encode the UDC header and compressed UDC block. The PDCP layer device can configure data, generate and configure the PDCP header 1j-20, first connect the SDAP header and connect the PDCP header, and then transmit the header and data to the lower layer for data processing in the RLC layer device and the MAC layer device.

[0240] Fig.11 An embodiment of a method for effectively performing user data compression in a case where an SDAP layer device or an SDAP header is configured through an RRC message according to the present disclosure is shown.

[0241] Reference Fig.11 , the SDAP layer device or SDAP header is configured as by Figure 5The RRC message shown is used, and user data compression (UDC) is configured, if the SDAP layer device receives SDAP control data 1k-05 from the upper layer, the SDAP layer device can configure the 1-bit D / C field of the SDAP header to 1, and indicate that the SDAP user data (SDAP data PDU) is SDAP user data or SDAP header, and can configure the 1-bit D / C field of the SDAP header to 0, and indicate that the SDAP control data (SDAP control PDU) is SDAP control data. The sending PDCP layer device may not perform the user data compression process (indicated by reference numeral 10-07) on the SDAP control data received from the upper SDAP layer device. In addition, the sending PDCP layer device does not generate a UDC header for the SDAP control data (indicated by reference numeral 1k-10). In addition, if integrity protection is configured, the sending PDCP layer device may apply integrity protection to the PDCP header and SDAP control data before performing the encoding process, and then not perform encoding of the SDAP control data. In addition, the transmitting PDCP layer device may configure a PDCP header and attach it to the front of the SDAP control data, and transmit the data to the lower layer device.

[0242] The 1-bit indicator of the PDCP header proposed in the embodiments of the present disclosure, Fig.10 or Fig.11 The SDAP control data or the 1-bit D / C field of the SDAP header provides a function of indicating the presence or absence of the UDC header, or, when the user compression process is not applied to the SDAP header and the data received from the upper layer, the UDC header is omitted, and the 1-bit indicator of the PDCP header can indicate that no UDC header is attached to reduce overhead.

[0243] In the following content of the present disclosure, an embodiment proposes the operation of a PDCP layer device of a UE or base station that performs different data processing by distinguishing between a case where a sending or receiving PDCP layer device of an extended embodiment of the present disclosure receives an SDAP header and upper layer data from an upper layer device or a lower layer device and a case where a sending or receiving PDCP layer device receives SDAP control data.

[0244] - If the SDAP layer device or SDAP header is configured as Figure 5 The RRC message shown uses and configures User Data Compression (UDC),

[0245] ■If the data (e.g., PDCP SDU) received from an upper layer device (SDAP layer device) includes an SDAP header and upper layer data, or if the data is not SDAP control data, (when processing the data (PDCP SDU) received from the upper layer device), the transmitting PDCP layer device may first identify the 1-bit D / C field of the SDAP header or SDAP control data and distinguish them. In addition, a 1-bit indicator of the UDC header or a 1-bit indicator of the PDCP header may indicate whether it is an SDAP header or SDAP control data (or whether it is compressed). As another method, if the size of the received data exceeds 1 byte, it may be determined that the received data is not SDAP control data and includes an SDAP header and data therein. However, if the size of the received data is 1 byte, it may be determined that the received data is SDAP control data.

[0246] ◆The sending PDCP layer device executes the embodiment of the present disclosure ( Fig.10 For example, the sending PDCP layer device applies the UDC compression process except the SDAP header, performs integrity protection if integrity protection is configured, appends the UDC header after the SDAP header, encodes the UDC header and compressed data except the SDAP header, connects the encoded UDC header and compressed data to the front of the PDCP header, and sends it to the lower layer device.

[0247] ■If the data (e.g., PDCP SDU) received from an upper layer device (SDAP layer device) does not include an SDAP header and upper layer data, or if the data is SDAP control data (when processing data (PDCP SDU) received from an upper layer device), the transmitting PDCP layer device may first identify the 1-bit D / C field of the SDAP header or SDAP control data and distinguish them. In addition, a 1-bit indicator of the UDC header or a 1-bit indicator of the PDCP header may indicate whether it is an SDAP header or SDAP control data (or whether it is compressed). As another method, if the size of the received data exceeds 1 byte, it may be determined that the received data is not SDAP control data and includes an SDAP header and data therein. However, if the size of the received data is 1 byte, it may be determined that the received data is SDAP control data.

[0248] ◆The sending PDCP layer device executes the embodiment of the present disclosure ( Fig.11 For example, if integrity protection is configured in the SDAP control data, the sending PDCP layer device performs integrity protection, does not apply the UDC compression process or encoding process, does not generate a UDC header, connects the PDCP header to it, and sends it to the lower layer device.

[0249] ■If the data (e.g., PDCP PDU) received from the lower layer device (RLC layer device) includes an SDAP header and upper layer data, or if the data is not SDAP control data, (when processing the data (PDCP PDU) received from the lower layer device), the receiving PDCP layer device may first identify the 1-bit D / C field of the SDAP header or SDAP control data and distinguish them. As another method, a 1-bit indicator of a UDC header or a 1-bit indicator of a PDCP header may be identified and distinguished. As another method, the receiving PDCP layer device may perform data processing by identifying the size of the data received from the lower layer. For example, if the size of the data other than the PDCP header of the received data is 1 byte, SDAP control data may be indicated, and if the data size exceeds 1 byte, SDAP user data (or SDAP header) may be indicated. In another method, if the size of the data other than the PDCP header is 2 bytes (1-byte UDC header and 1-byte SDAP control data), SDAP control data may be indicated, and if the data size exceeds 2 bytes, SDAP user data (or SDAP header) may be indicated. In another method, if the size of the data received from the lower layer is equal to the sum of the size of the PDCP header, the size of the UDC header, and the size of the SDAP control data, the SDAP control data may be indicated, and in the above method, if the data size exceeds the sum of the size of the PDCP header, the size of the UDC header, and the size of the SDAP control data, the SDAP user data (or SDAP header) may be indicated. As another method, for example, in applying the above Fig.11 In the case of an embodiment, the receiving PDCP layer device identifies the size of the data received from the lower layer, and if the size of the data excluding the PDCP header is 1 byte, the receiving PDCP layer device may indicate SDAP control data, and if the data size exceeds 1 byte, the receiving PDCP layer device may indicate SDAP user data (or SDAP header). In another method, if the size of the data received from the lower layer is equal to the sum of the size of the PDCP header and the size of the SDAP control data, the receiving PDCP layer device may indicate SDAP control data, and if the data size exceeds the sum of the size of the PDCP header and the size of the SDAP control data, the receiving PDCP layer device may indicate SDAP user data (or SDAP header).

[0250] ◆The receiving PDCP layer device executes the embodiment of the present disclosure ( Fig.10 For example, the receiving PDCP layer device performs a decryption process on the UDC header and data except the SDAP header, performs integrity protection if integrity protection is configured, and performs a UDC decompression process when there is an indicator indicating that the UDC compression process has been applied to the UDC header, and sends it to the upper layer device.

[0251] ■If the data (e.g., PDCP PDU) received from the lower layer device (RLC layer device) does not include the SDAP header and the upper layer data, or if the data is SDAP control data (When processing the data (PDCP PDU) received from the lower layer device, the receiving PDCP layer device may first identify the 1-bit D / C field of the SDAP header or the SDAP control data and distinguish them. As another method, a 1-bit indicator of the UDC header or a 1-bit indicator of the PDCP header may be identified and distinguished. As another method, the receiving PDCP layer device may perform data processing by identifying the size of the data received from the lower layer. For example, if the size of data excluding the PDCP header of the received data is 1 byte, SDAP control data may be indicated, and if the data size exceeds 1 byte, SDAP user data (or SDAP header) may be indicated. In another method, if the size of the data excluding the PDCP header is 1 byte, SDAP control data may be indicated. If the size of the data received from the lower layer is 2 bytes (1-byte UDC header and 1-byte SDAP control data), SDAP control data may be indicated, and if the data size exceeds 2 bytes, SDAP user data (or SDAP header) may be indicated. In another method, if the size of the data received from the lower layer is equal to the sum of the size of the PDCP header, the size of the UDC header, and the size of the SDAP control data, SDAP control data may be indicated, and in the above method, if the data size exceeds the sum of the size of the PDCP header, the size of the UDC header, and the size of the SDAP control data, SDAP user data (or SDAP header) may be indicated. As another method, for example, in applying the above Fig.11 In the case of an embodiment, the receiving PDCP layer device identifies the size of the data received from the lower layer, and if the size of the data excluding the PDCP header is 1 byte, the receiving PDCP layer device may indicate SDAP control data, and if the data size exceeds 1 byte, the receiving PDCP layer device may indicate SDAP user data (or SDAP header). In another method, if the size of the data received from the lower layer is equal to the sum of the size of the PDCP header and the size of the SDAP control data, the receiving PDCP layer device may indicate SDAP control data, and if the data size exceeds the sum of the size of the PDCP header and the size of the SDAP control data, the receiving PDCP layer device may indicate SDAP user data (or SDAP header).

[0252] ◆The receiving PDCP layer device executes the embodiment of the present disclosure ( Fig.11For example, the receiving PDCP layer device does not perform a decoding process for the SDAP control data, performs integrity protection if integrity protection is configured, does not perform a UDC decompression process because there is no UDC header, and UDC compression is not applied to the SDAP control data, and sends the control data to the lower layer device.

[0253] Fig.12 The Ethernet header compression (EthHC) method proposed when the SDAP header or layer device is configured according to the present disclosure is shown.

[0254] exist Fig.12 In the embodiment, uplink data 11-05 may be generated as data corresponding to services such as video transmission, photo transmission, network search, and VoLTE. The data generated by the application layer device may be processed by TCP / IP or UDP corresponding to the network data transmission layer, or may be processed by Ethernet protocol and SDAP layer devices, and respective headers 11-10, 11-15, and 11-20 (upper layer header, Ethernet header, or SDAP header) may be configured, and may be transmitted to the PDCP layer. When the PDCP layer receives data (PDCP SDU) from the upper layer, the PDCP layer may perform the following process.

[0255] When the header compression (ROHC) or Ethernet header compression process is configured to Figure 5 When the RRC message shown is used in the PDCP layer, the PDCP layer can compress the TCP / IP header through ROHC, as shown in reference numeral 11-21, and can perform an Ethernet header compression process on the Ethernet header other than the SDAP header in the PDCP layer device, as shown in reference numeral 11-22. In addition, the PDCP layer can configure a separate EHC header, which includes a field for indicating whether to compress the Ethernet header, a field for indicating which fields of the Ethernet header are compressed (omitted) or not compressed (non-omitted), or a context identifier as shown in reference numeral 11-40, and a separate EHC header can be configured before the compressed header.

[0256] When integrity verification is configured, the PDCP layer can perform integrity protection on the SDAP header, PDCP header, EHC header, compressed header, and data. In addition, the PDCP layer can perform an encryption process on compressed headers, data, and EHC headers other than the SDAP header, and can configure the PDCP PDU by configuring the PDCP headers 1l-30. The receiving terminal can perform a decryption process on compressed headers, data, and EHC headers other than the SDAP header in the receiving PDCP layer device. In addition, when integrity protection or verification procedures are configured, the receiving terminal can perform integrity verification on the PDCP header, EHC header, compressed header, and data. In the above, the PDCP layer device includes a header compressor / decompressor, determines whether to perform header compression on each data configured by the RRC message, and uses the header compressor / decompressor.

[0257] The transmitting terminal compresses the Ethernet header or the upper layer header (e.g., TCP / IP header) using the header compressor in the transmitting PDCP layer device, and the receiving terminal performs header decompression on the Ethernet header or the upper layer header (e.g., TCP / IP header) by using the header decompressor in the receiving PDCP layer device. In the above, the encryption process or the decryption process can be applied to the EHC header other than the PDCP header or the SDAP header, the Ethernet header compressed by the Ethernet header compression method, the upper layer header compressed by the ROHC header compression method, or the remaining data. In addition, the integrity protection or verification process can be applied to the PDCP header, the SDAP header, the EHC header, the Ethernet header compressed by the Ethernet header compression method, the upper layer header compressed by the ROHC header compression method, or the remaining data.

[0258] Above Fig.12 The process can be applied to the case where the UE performs downlink data header compression as well as uplink header compression. In addition, the description of uplink data can also be applied to downlink data.

[0259] The method for performing Ethernet header compression on an Ethernet header proposed by the present disclosure is a method for reducing the size of a header by indicating only information that has changed or is about to change and omitting fields indicating or having fixed information. Therefore, first, information including complete header information and configuration information for compression (e.g., an identifier (type) specific to a business (or service) of an Ethernet protocol, a sequence number specific to a business (or service), information related to a compression rate, or an indicator indicating whether compression has occurred) can be sent. In addition, fields (e.g., a send address field or a receive address field (MAC address)), a leading field, a start of frame delimiter (SFD), a frame checksum (FCS), an Ethernet type field, a Q-Tage field, etc.) correspond to information that has not changed compared to all the information first sent, or fixed information can be omitted or not sent, and the header can be configured by including only fields corresponding to information that has changed or can change, so as to reduce the size of the header. Alternatively, when feedback is received in response to successfully receiving data with a complete header or information that has not changed compared to all the information first sent, or fields corresponding to fixed information (e.g., a transmit address field or a receive address field (MAC address), a preamble field, a frame start delimiter (SFD), a frame checksum (FCS), an Ethernet type field, a Q-Tage field, etc.) can be omitted or not sent, the header fields can be compressed and the header can be configured by including only fields corresponding to the information that has changed or can change so as to reduce the size of the header.

[0260] As another method, since compressible fields and incompressible fields are distinguished, and the value of the compressible field can be assumed to include the same value as the field value of the complete header that was first transmitted, only the compressible field can be compressed (or omitted) and transmitted, while the incompressible field can always be transmitted without being compressed (or omitted). In addition, when the value of even one field in the compressible field has changed from the field value of the complete header that was previously transmitted, the complete header can be transmitted again. In addition, each time a complete header is received, the receiving PDCP layer device can always send feedback to the transmitting PDCP layer device indicating that the complete header is well received.

[0261] The Ethernet header compression method proposed above may not be applicable to the SDAP control data (SDAP control PDU) and SDAP header of the upper layer device. Therefore, in the network implementation, the QoS information of the uncompressed SDAP control data or SDAP header can be read, and the transmission resources can be quickly scheduled. In addition, in the UE implementation, since the QoS information can be read from the SDAP control data or SDAP header before the decompression occurs at the receiving terminal, the implementation can be simplified. In addition, since the transmitting terminal can perform the generation of the SDAP control data or SDAP header in parallel with the header, data compression processing process or encryption process of the PDCP layer device, the data processing time can be reduced.

[0262] In addition, a sending PDCP layer device or a receiving PDCP layer device can identify a 1-bit indicator of an SDAP header of data received from an upper layer device or a lower layer device to distinguish whether it is SDAP control data (SDAP control PDU) or SDAP user data (SDAP data PDU) with an SDAP header, and can perform data processing as described above. In another method, a sending PDCP layer device or a receiving PDCP layer device can identify the size of data received from an upper layer device or a lower layer device (for example, whether the data size exceeds 1 byte, when the data size is 1 byte, it can be determined as SDAP control data, and when the data size exceeds 1 byte, it can be determined as SDAP user data) to distinguish whether it is SDAP control data (SDAP control PDU) or SDAP user data (SDAP data PDU) with an SDAP header, and can perform data processing as described above.

[0263] In the following content of the present disclosure, with respect to a data service assuming data loss, or when a UDC compression method or a user data compression process is applied to a PDCP layer device connected to an RLC UM mode or configured in a UM mode, a method for enabling a user data compression process that is insensitive to loss to be performed is proposed.

[0264] In the present disclosure, a UDC compression method considering loss or a first method of performing user data compression is as follows.

[0265] According to the first method, Figure 5The second timer value may be configured by an RRC message in the bearer or PDCP layer device, and the second timer may be configured or applied together when a data compression method (e.g., uplink data compression (UDC)) is configured in the bearer or PDCP layer device. The second timer value may be configured to be a value less than the first timer value, and may be triggered or started when a sequence number gap occurs when the receiving PDCP layer device rearranges the received data based on an ascending order of the PDCP sequence number or COUNT value. In addition, the second timer may be stopped when the sequence number gap is filled. When the second timer expires because the sequence number gap is not filled, the receiving PDCP layer device may include an instruction to initialize a buffer for the data compression method or information indicating that a data decompression failure has occurred in the PDCP control data (PDCP control PDU), and send it to the sending PDCP layer device; and the receiving PDCP layer device may initialize the buffer for the data compression method immediately, or may initialize the buffer for the data compression method upon receiving an instruction to initialize the buffer for the data compression method or an indication that the buffer has been initialized from the sending PDCP layer device. In the above, the second timer value may be configured in consideration of the retransmission time of the MAC layer device or the RLC layer device or the time taken until successful transmission is recognized. In addition, when the above second timer expires, the receiving PDCP layer device may discard the data received before receiving an instruction to initialize the buffer for the data compression method from the sending PDCP layer device or indicating that the buffer has been initialized, without performing decoding or user data decompression process.

[0266] In the present disclosure, a UDC compression method considering loss or a second method of performing user data compression is as follows.

[0267] According to the second method, Figure 5The third timer value may be configured by an RRC message in the bearer or PDCP layer device, and when a data compression method (e.g., uplink data compression (UDC)) is configured in the bearer or PDCP layer device, the third timer may be configured or applied together. The third timer value may be configured to be a value less than the first timer value, and when the third timer value is configured, the receiving PDCP layer device may start the third timer. The third timer may be used when the receiving PDCP layer device includes an instruction to initialize a buffer for a data compression method in PDCP control data (PDCP control PDU) and periodically sends it to the sending PDCP layer device. That is, whenever the third timer expires (whenever the amount of data compressed by another method or to which the UDC process is applied and transmitted to the lower layer reaches the maximum amount of data), the receiving PDCP layer device may send an instruction to initialize a buffer for a data compression method to the sending PDCP layer device by including the instruction in the PDCP control data (PDCP control PDU). In addition, the receiving PDCP layer device may restart the third timer immediately after sending the PDCP control data or after the timer expires, or after receiving an instruction to initialize a buffer for a data compression method or an indication that the buffer has been initialized from the sending PDCP layer device.

[0268] As another method, the third timer can be applied to the sending PDCP layer device, and the sending PDCP layer device can start the third timer to periodically initialize the buffer for the data compression method. That is, whenever the third timer expires, the sending PDCP layer device can initialize the buffer for the data compression method, and configure and send a 1-bit indicator of the UDC header to indicate that the receiving PDCP layer device initializes the buffer or provides an indication that the buffer is initialized. In addition, the sending PDCP layer device can restart the third timer immediately after initializing the buffer or after the timer expires, or after configuring the 1-bit indicator in the UDC header and sending it. In the above, the retransmission time of the MAC layer device or the RLC layer device or the time taken until the successful transmission is identified can be considered to configure the third timer value. In addition, when the above-mentioned third timer expires, the data received before receiving an instruction to initialize the buffer for the data compression method from the sending PDCP layer device or indicating that the buffer has been initialized is discarded without performing a decoding or user data decompression process.

[0269] In the present disclosure, a UDC compression method considering loss or a third method of performing user data compression is as follows.

[0270] The third method may include: configuration information about a predefined library or dictionary, which is to be input and used in a buffer when a data compression method is performed; and information indicating whether to perform a data compression or decompression process when the buffer is updated with a series of packets by inputting the library or dictionary information into the buffer and performing compression when the data compression or decompression method is started, or by inputting the predefined library or dictionary information into the buffer for data compression or decompression, no longer updating the buffer with a series of data, and keeping the library or dictionary information as a fixed buffer value, to indicate whether to perform a data compression or decompression process based on a fixed buffer value. Therefore, if the indicator of using a fixed buffer value is configured in the above, the transmitting PDCP layer device can apply the user data compression process to the data by using the fixed buffer value without continuously updating the buffer with the data to which the user data compression is applied, which is the same as Figure 7 or Figure 8 In addition, the receiving PDCP layer device does not update the buffer value each time the user data decompression process is performed on the received data, and can also perform the user data decompression process by using a fixed buffer value in the same manner as the transmitting PDCP layer device and applying the fixed buffer value to the received data. In the present disclosure, a fourth method of performing user data compression or a UDC compression method considering loss is as follows.

[0271] The fourth method may include configuration information about an RLC layer device connected to a PDCP layer device to which a data compression method is applied. The configuration information of the RLC layer device may include an indicator or information indicating whether to transmit data received in a receiving operation of the RLC layer device to the PDCP layer device by arranging the order of received data based on an RLC sequence number (sequential delivery function configuration); or whether to send unsegmented data or reassembled data about received data to the PDCP layer device regardless of the order of the RLC sequence number (out-of-order delivery function configuration). Therefore, if the RLC layer device is configured based on the above-mentioned in-order delivery function, the receiving PDCP layer device may trigger and configure PDCP control data indicating that when the received data is reordered based on an ascending order of a PDCP sequence number or a COUNT value, if a sequence number gap occurs, a user data decompression error occurs, and the receiving layer device may send the PDCP control data to the sending PDCP layer device. That is, the receiving PDCP layer device may include an instruction to initialize a buffer for a data compression method or information indicating that a data decompression failure has occurred in the PDCP control data (PDCP control PDU), and send it to the transmitting PDCP layer device; and the receiving PDCP layer device may immediately initialize the buffer for the data compression method, or may initialize the buffer for the data compression method upon receiving an instruction to initialize a buffer for a data compression method or an indication that the buffer has been initialized from the transmitting PDCP layer device. In addition, if a gap in the PDCP sequence number or COUNT value occurs in the above process, the receiving PDCP layer device may discard the data received before receiving an instruction to initialize a buffer for a data compression method or an indication that the buffer has been initialized from the transmitting PDCP layer device, without performing a decoding or user data decompression process.

[0272] In the present disclosure, when a PDCP discard timer is driven in a transmitting terminal PDCP layer device and data that has not been transmitted due to expiration of the PDCP discard timer and to which a user compression procedure (UDC) has been applied is discarded, the UE operates as follows.

[0273] In detail, whenever the UE receives data from an upper layer device, the UE may drive a PDCP discard timer for each received data. If the UE is configured to perform uplink data compression on the PDCP layer device, the UE performs uplink data compression on the received data (PDCP SDU). In addition, the UE performs uplink data compression (UDC), updates the buffer according to the data compression, and configures a transmit UDC buffer. When uplink data compression (UDC) is performed in the above, the UE may compress the PDCP SDU received from the upper layer into UDC compressed data (UDC block) having a smaller size. In addition, the UE configures a UDC header for the compressed UDC compressed data. The UDC header may include an indicator indicating whether uplink data compression has been performed (for example, a 1-bit indicator in the UDC header is 0, which may indicate that UDC is applied, and a 1-bit indicator is 1, which may indicate that UDC is not applied).

[0274] If uplink data compression (UDC) is performed on data (PDCP SDU) received from an upper layer and the UDC buffer is updated, the receiving terminal PDCP layer device may calculate a checksum bit to identify the validity of the updated UDC buffer and include the checksum bit in the UDC buffer (the checksum bit may have a predetermined length and be configured, for example, by 4 bits).

[0275] If the UE is configured, the UE performs integrity protection on the data with or without uplink data decompression applied, performs encryption of the data, and transmits the encrypted data to a lower layer.

[0276] If the transmitting PDCP layer device discards data that has not been sent due to expiration of the PDCP discard timer and on which UDC compression has been performed, the UE may send data corresponding to the next PDCP sequence number of the discarded data, may discard the remaining data (stored data having a PDCP sequence number greater than the next PDCP sequence number of the discarded data, to which user data compression has been applied and has not been sent), and if the data has been delivered to a lower layer device, an indicator of discarding the data may be sent to the lower layer device. The UE may stop data transmission to the transmitting PDCP layer device until a PDCP control PDU indicating that a checksum failure has occurred is received. Because the middle or part of the UDC compressed data is discarded, user data compression has been performed in advance, and for data (e.g., PDCP PDU) having a higher PDCP sequence number than the discarded data, it is obvious that a checksum failure will occur in the receiving PDCP layer device. Therefore, when sending data corresponding to the next PDCP sequence number of the discarded data, it can be expected that the receiving PDCP layer device will recognize the checksum failure and send a PDCP control PDU.

[0277] Therefore, when the transmitting PDCP layer device receives a PDCP control PDU indicating that a checksum failure has occurred, or before receiving the PDCP control PDU, the transmitting PDCP layer device can initialize a transmission buffer for user data compression (if the transmitting UDC buffer has been initialized in the above, it is not initialized), and can perform the user data compression process again starting from the data for which the PDCP discard timer has not expired and has not been transmitted, or starting from the last transmitted data for which the PDCP discard timer has not expired (data corresponding to the discarded data and the next PDCP sequence number transmitted), and can encrypt, generate and prepare data (e.g., PDCP PDU) by allocating in ascending order starting from a new PDCP sequence number or a first PDCP sequence number that has not been transmitted. After receiving the PDCP control PDU indicating that a checksum failure has occurred, the transmission of the newly generated and prepared data can be resumed in the transmitting PDCP layer device. That is, the data can be transmitted to the lower layer device.

[0278] Fig.13 The operation of the UE in the present disclosure is shown.

[0279] If a UDC compression or decompression process is configured in the PDCP layer device of the sending terminal of UE 1m-01, and the PDCP layer device of the sending terminal receives PDCP control data (PDCP control PDU) indicating that a checksum failure has occurred from the PDCP layer device of the receiving terminal (operation 1m-05), the PDCP layer device of the sending terminal can initialize a sending UDC buffer for user data compression (UDC compression). Optionally, if a UDC compression or decompression process is configured in the PDCP layer device, and the PDCP layer device of the sending terminal receives PDCP control data (PDCP control PDU) indicating that a checksum failure has occurred from the PDCP layer device of the receiving terminal, the data discard process (operation 1m-10) can be performed by applying the first method or the second method proposed in the present disclosure to data that has been pre-generated, stored, pre-processed, or the PDCP discard timer has not expired. In addition, if the RLC layer device that has received the data discard indicator during the data discard process is an LTE RLC layer device (operation 1m-15), the data discard method of the LTE RLC layer device proposed above in the present disclosure (operation 1m-20) can be applied, and if the RLC layer device that has received the data discard indicator during the data discard process is an NR RLC layer device (operation 1m-15), the data discard method of the NR RLC layer device proposed above in the present disclosure (operation 1m-25) can be applied. Fig.14 The structure of a UE to which the embodiments of the present disclosure can be applied is shown.

[0280] Referring to the drawing, the UE may include a Radio Frequency (RF) processor 1n-10, a baseband processor 1n-20, a memory 1n-30, and a controller 1n-40.

[0281] The RF processor 1n-10 can perform functions for sending and receiving signals through wireless channels, such as frequency band conversion, amplification, etc. of signals. That is, the RF processor 1n-10 can up-convert the baseband signal provided by the baseband processor 1n-20 into an RF band signal, and can send the RF band signal through the antenna, and can down-convert the RF band signal received by the antenna into a baseband signal. For example, the RF processor 1n-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. In the accompanying drawings, only one antenna is shown, but the UE may include multiple antennas. In addition, the RF processor 1n-10 may include multiple RF chains. In addition, the RF processor 1n-10 may perform beamforming. For beamforming, the RF processor 1n-10 may adjust the phase and amplitude of each signal sent and received through multiple antennas or antenna elements. In addition, the RF processor may perform MIMO, and may receive multiple layers when performing MIMO operations. The RF processor 1n-10 can perform receive beam scanning by appropriately configuring multiple antennas or antenna elements under the control of the controller, or can adjust the direction and beam width of the receive beam so that the receive beam is coordinated with the transmit beam.

[0282] The baseband processor 1n-20 can perform the conversion function between the baseband signal and the bit string according to the physical layer standard of the system. For example, during data transmission, the baseband processor 1n-20 generates complex symbols by encoding and modulating the transmission bit string. In addition, during data reception, the baseband processor 1n-20 can reconstruct the received bit string by demodulating and decoding the baseband signal provided from the RF processor 1n-10. For example, according to the orthogonal frequency division multiplexing (OFDM) scheme, during data transmission, the baseband processor 1n-20 can generate complex symbols by encoding and modulating the transmission bit string, and the complex symbols can be mapped to subcarriers, and then OFDM symbols can be configured by inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. In addition, during data reception, the baseband processor 1n-20 can divide the baseband signal provided from the RF processor 1n-10 into OFDM symbol units, and the signal mapped to the subcarrier can be reconstructed by fast Fourier transform (FFT) operation, and then the received bit string can be reconstructed by demodulation and decoding.

[0283] The baseband processor 1n-20 and the RF processor 1n-10 can send or receive signals as described above. Therefore, the baseband processor 1n-20 or the RF processor 1n-10 can be referred to as a transmitter, a receiver, a transceiver, or a communication unit. In addition, at least one of the baseband processor 1n-20 and the RF processor 1n-10 may include multiple communication modules to support a variety of different radio access technologies. In addition, at least one of the baseband processor 1n-20 and the RF processor 1n-10 may include different communication modules to process signals of different frequency bands. For example, different radio access technologies may include LTE networks, NR networks, etc. In addition, different frequency bands may include ultra-high frequency (SHF) (e.g., 2.5 GHz or 5 GHz) bands and millimeter wave (e.g., 60 GHz) bands.

[0284] The memory 1n-30 may store data such as basic programs, application programs, and configuration information for UE operation. The memory 1n-30 may provide the stored data according to a request from the controller 1n-40.

[0285] The controller 1n-40 may control the overall operation of the UE. For example, the controller 1n-40 may send or receive a signal through the baseband processor 1n-20 or the RF processor 1n-10. In addition, the controller 1n-40 may record and read data in the memory 1n-30. To this end, the controller 1n-40 may include at least one processor. For example, the controller 1n-40 may include a communication processor (CP) for performing communication control and an application processor (AP) for controlling an upper layer (such as an application).

[0286] Fig.15 is a block diagram showing TRP in a wireless communication system to which the present disclosure may be applied.

[0287] like Fig.15 As shown, the base station may include an RF processor 1o-10, a baseband processor 1o-20, a communication unit 1o-30, a memory 1o-40 and a controller 1o-50.

[0288] The RF processor 1o-10 can perform functions for sending or receiving signals through a wireless channel, such as frequency band conversion, amplification, etc. of the signal. That is, the RF processor 1o-10 can up-convert the baseband signal provided by the baseband processor 1o-20 to an RF band signal to send the RF band signal through the antenna, and can down-convert the RF band signal received by the antenna to a baseband signal. For example, the RF processor 1o-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. In the figure, only one antenna is shown, but the base station can have multiple antennas. In addition, the RF processor 1o-10 may include multiple RF chains. In addition, the RF processor 1o-10 can perform beamforming. For beamforming, the RF processor 1o-10 can adjust the phase and amplitude of each signal sent and received by multiple antennas or antenna elements. The RF processor can perform downlink MIMO operations by sending one or more layers.

[0289] The baseband processor 1o-20 can perform a conversion function between a baseband signal and a bit string according to the physical layer standard of the first radio access technology. For example, during data transmission, the baseband processor 1o-20 can generate a complex symbol by encoding and modulating the transmission bit string. In addition, during data reception, the baseband processor 1o-20 can reconstruct the received bit string by demodulating and decoding the baseband signal provided from the RF processor 1o-10. For example, according to the OFDM scheme, during data transmission, the baseband processor 1o-20 can generate a complex symbol by encoding and modulating the transmission bit string, the complex symbol can be mapped to a subcarrier, and then the OFDM symbol can be configured by IFFT operation and CP insertion. In addition, during data reception, the baseband processor 1o-20 can divide the baseband signal provided from the RF processor 1o-10 in units of OFDM symbols, the signal mapped to the subcarrier can be reconstructed by FFT operation, and then the received bit string can be reconstructed by demodulation and decoding. The baseband processor 1o-20 or the RF processor 1o-10 can send or receive a signal as described above. Therefore, the baseband processor 1o-20 or the RF processor 1o-10 can be called a transmitter, a receiver, a transceiver, a communication unit or a wireless communication unit.

[0290] Communication unit 10-30 may provide an interface for communicating with other nodes in the network.

[0291] The memory 1o-40 may store data such as basic programs, applications, and configuration information for base station operation. Specifically, the memory 1o-40 may store information about bearers assigned to connected UEs, measurement results reported from connected UEs, and the like. In addition, the memory 1o-40 may store information as a criterion for determining whether to provide or terminate multiple connections to a UE. The memory 1o-40 may provide stored data according to a request from the controller 1o-50.

[0292] The controller 1o-50 can control the overall operation of the main base station. For example, the controller 1o-50 can send or receive a signal through the baseband processor 1o-20 or the RF processor 1o-10 or through the communication unit 1o-30. In addition, the controller 1o-50 can record and read data in the memory 1o-40. To this end, the controller 1o-50 may include at least one processor. In the above-mentioned detailed embodiments of the present disclosure, according to the detailed embodiments presented, the elements included in the present disclosure are expressed in the singular or plural. However, for the convenience of description, the singular form or the plural form is appropriately selected as the presented situation, and the present disclosure is not limited to elements expressed in the singular or plural. Therefore, an element expressed in the plural may also include a single element, or an element expressed in the singular may also include multiple elements.

[0293] The embodiments of the present disclosure described and shown in the specification and the drawings are merely specific examples, which are presented to easily explain the technical content of the present disclosure and help understand the present disclosure, and are not intended to limit the scope of the present disclosure. That is to say, it is obvious to those skilled in the art that other variations based on the technical concept of the present disclosure can be implemented. In addition, the above-mentioned various embodiments can be used in combination as needed. For example, a part of an embodiment of the present disclosure can be combined with a part of any other embodiment of the present disclosure to operate a base station and a terminal. In addition, the above-mentioned embodiments can be applied to other communication systems, and other variations based on the technical concept of the embodiments can also be implemented. For example, the embodiments can be applied to LTE systems, 5G or NR systems, etc.

Claims

1. A method performed by a transmitting device in a wireless communication system, the method comprising: In case Ethernet header compression EHC is not configured, identifying whether uplink data compression UDC is configured by a radio resource control RRC message; When the UDC is configured by the RRC message, sending first data compressed based on the UDC to the receiving device; Pre-processing a packet data convergence protocol PDCP protocol data unit PDU based on the UDC buffer; receiving, from the receiving device, an indicator indicating a checksum failure of decompression of the transmitted first data; initializing a UDC buffer based on the indicator; as well as The PDCP data PDUs other than the PDCP control PDUs in the pre-processed PDCP PDUs are discarded based on a discard indicator, wherein the discard indicator is submitted from the PDCP layer to a lower layer of the PDCP layer.

2. The method according to claim 1, further comprising: discarding at least one of: a pre-processed PDCP PDU for which a PDCP discard timer has not expired or a pre-processed PDCP PDU delivered to a lower layer, and The discard indicator of the PDCP data PDU is submitted to a lower layer based on the indicator indicating a checksum failure.

3. The method according to claim 1, further comprising: compressing second data based on the initialized UDC buffer; as well as transmitting the compressed second data and packet data including a UDC header indicating initialization of a UDC buffer to a receiving device, The reordering timer started in the receiving device is stopped based on the UDC header.

4. A method performed by a receiving device in a wireless communication system, the method comprising: receiving first data from a sending device; performing decompression of the first data based on uplink data compression (UDC), wherein the UDC is configured by a radio resource control (RRC) message when Ethernet header compression (EHC) is not configured; In the event that a checksum failure occurs when performing decompression, sending an indicator indicating the checksum failure to the sending device; and Initialize the receiving device's UDC buffer based on checksum failure, wherein PDCP data PDUs other than a Packet Data Convergence Protocol PDCP control protocol data unit PDU are discarded in the transmitting device based on a discard indicator, wherein the discard indicator is submitted from the PDCP layer to a lower layer of the PDCP layer, The PDCP data PDU and the PDCP control PDU are included in the PDCP PDU that has been pre-processed based on the UDC buffer of the transmitting device, and the UDC buffer of the transmitting device is used to generate the first data.

5. The method according to claim 4, in, At least one of the following is further discarded in the transmitting device: a pre-processed PDCP PDU whose PDCP discard timer has not expired or a pre-processed PDCP PDU delivered to a lower layer, and The discard indicator is submitted to a lower layer in the sending device based on the indicator indicating a checksum failure.

6. The method according to claim 4, in, Initializing the UDC buffer of the receiving device also includes: receiving, from the sending device, packet data including compressed second data in response to the sending of the indicator indicating a checksum failure; identifying whether the UDC header of the compressed second data indicates initialization of a UDC buffer of the transmitting device; and initializing the UDC buffer of the receiving device if the UDC header indicates initialization of the UDC buffer of the sending device, and The method further includes stopping a reordering timer started in the receiving device based on a UDC header indicating initialization of a UDC buffer of the sending device.

7. A transmitting device in a wireless communication system, the transmitting device comprising: Transceiver; and The controller is configured as: In case Ethernet header compression EHC is not configured, identifying whether uplink data compression UDC is configured by a radio resource control RRC message; When the UDC is configured by the RRC message, sending first data compressed based on the UDC to the receiving device; Pre-processing a packet data convergence protocol PDCP protocol data unit PDU based on the UDC buffer; controlling the transceiver to receive, from the receiving device, an indicator indicating a checksum failure of decompression of the transmitted first data; initializing a UDC buffer based on the indicator; as well as The PDCP data PDUs other than the PDCP control PDUs in the pre-processed PDCP PDUs are discarded based on a discard indicator, wherein the discard indicator is submitted from the PDCP layer to a lower layer of the PDCP layer.

8. The transmitting device according to claim 7, in, The controller is further configured to discard at least one of: a pre-processed PDCP PDU whose PDCP discard timer has not expired or a pre-processed PDCP PDU delivered to a lower layer, and The discard indicator of the PDCP data PDU is submitted to a lower layer based on the indicator indicating a checksum failure.

9. The transmitting device according to claim 7, in, The controller is further configured to compress the second data based on the initialized UDC buffer; and control the transceiver to send the compressed second data and the packet data including the UDC header indicating the initialization of the UDC buffer to the receiving device, and The reordering timer started in the receiving device is stopped based on the UDC header.

10. A receiving device in a wireless communication system, the receiving device comprising: Transceiver; and The controller is configured as: Controlling the transceiver to receive first data from the sending device; performing decompression of the first data based on uplink data compression (UDC), wherein the UDC is configured by a radio resource control (RRC) message when Ethernet header compression (EHC) is not configured; In the event that a checksum failure occurs during decompression, controlling the transceiver to send an indicator indicating the checksum failure to the transmitting device; and Initialize the receiving device's UDC buffer based on checksum failure, wherein PDCP data PDUs other than a Packet Data Convergence Protocol PDCP control protocol data unit PDU are discarded in the transmitting device based on a discard indicator, wherein the discard indicator is submitted from the PDCP layer to a lower layer of the PDCP layer, The PDCP data PDU and the PDCP control PDU are included in the PDCP PDU that has been pre-processed based on the UDC buffer of the transmitting device, and the UDC buffer of the transmitting device is used to generate the first data.

11. The receiving device according to claim 10, wherein: The controller is also configured to: controlling the transceiver to receive packet data including compressed second data from the transmitting device; identifying whether a UDC header of the compressed second data indicates initialization of a UDC buffer of the sending device; Initializing the UDC buffer of the receiving device in case the UDC header indicates initialization of the UDC buffer of the sending device; as well as Based on the UDC header indicating the initialization of the UDC buffer of the transmitting device, a reordering timer started in the receiving device is stopped.

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