COMMUNICATION METHOD, COMMUNICATION DEVICE, NETWORK NODE, USER EQUIPMENT, AND CHIPSET

Abstract

A transmission-side PDCP entity generates a PDCP PDU including a connection service data unit (SDU) by performing PDCP connection processing by which a plurality of PDCP SDUs are connected. A reception-side PDCP entity performs PDCP separation processing by which the plurality of PDCP SDUs are separated from the connection SDU included in the PDCP PDU. A first communication device, which includes one PDCP entity, transmits control information used for controlling at least one of the PDCP connection processing or the PDCP separation processing to a second communication device including the other PDCP entity.

Description

[Technical Field]

[0001] The present disclosure relates to a communication method and a communication device for use in a mobile communication system. [Background technology]

[0002] In mobile communication systems that comply with the 3GPP (3rd Generation Partnership Project) standard, the Packet Data Convergence Protocol (PDCP) is used as a protocol for performing header compression / decompression, encryption / decryption, etc. (see, for example, Non-Patent Document 1).

[0003] In communication between a base station and a user device, a transmitting PDCP entity adds a PDCP header to a PDCP SDU (Service Data Unit) from an upper layer to generate a PDCP PDU (Protocol Data Unit), after which a transmitting RLC (Radio Link Control) entity and a transmitting MAC (Medium Access Control) entity add an RLC header and a MAC header, respectively. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP Technical Specification: TS 38.323 V16.3.0 (2021-03), “Packet Data Convergence Protocol (PDCP) specification (Release 16)” Summary of the Invention [Means for solving the problem]

[0005] A communication method according to a first aspect is a method used in a mobile communication system having a pair of Packet Data Convergence Protocol (PDCP) entities, including a transmitting PDCP entity that transmits PDCP PDUs (Protocol Data Units) and a receiving PDCP entity that receives the PDCP PDUs. The communication method includes the steps of: the transmitting PDCP entity performing a PDCP concatenation process to concatenate a plurality of PDCP SDUs (Service Data Units) to generate the PDCP PDU including a concatenated SDU; the receiving PDCP entity performing a PDCP demultiplexing process to demultiplex the plurality of PDCP SDUs from the concatenated SDUs included in the PDCP PDU; and transmitting control information used for controlling at least one of the PDCP concatenation process and the PDCP demultiplexing process from a first communication device having one of the pair of PDCP entities to a second communication device having the other PDCP entity of the pair of PDCP entities.

[0006] A communication device according to a second aspect is a device used in a mobile communication system having a pair of PDCP entities, including a transmitting PDCP entity that transmits PDCP (Packet Data Convergence Protocol) PDUs (Protocol Data Units) and a receiving PDCP entity that receives the PDCP PDUs. The communication device includes a control unit that has either the transmitting PDCP entity or the receiving PDCP entity. The transmitting PDCP entity performs PDCP concatenation processing to concatenate multiple PDCP SDUs (Service Data Units) to generate the PDCP PDU including a concatenated SDU. The receiving PDCP entity performs PDCP deconvolution processing to deconvolute the multiple PDCP SDUs from the concatenated SDUs included in the PDCP PDU. The control unit transmits control information used to control at least one of the PDCP concatenation processing and the PDCP deconvolution processing to another communication device. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. [Figure 3] A diagram showing the configuration of a gNB (base station) according to one embodiment. [Figure 4] FIG. 10 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data. [Figure 5] FIG. 1 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals). [Figure 6] FIG. 10 is a diagram illustrating an example of processing of each layer in the protocol stack of the radio interface of the user plane. [Figure 7] FIG. 1 illustrates a PDCP PDU according to an embodiment. [Figure 8] A diagram showing PDCP concatenation processing and PDCP separation processing in a downlink according to one embodiment. [Figure 9] A diagram showing PDCP concatenation processing and PDCP separation processing in an uplink according to one embodiment. [Figure 10] FIG. 10 is a diagram illustrating transmission and reception of control information according to an embodiment. [Figure 11] FIG. 10 is a diagram showing delimiter codes according to the first embodiment. [Figure 12] FIG. 2 is a diagram illustrating the operation of the first embodiment. [Figure 13] FIG. 10 is a diagram illustrating the operation of the second embodiment. [Figure 14] FIG. 10 is a diagram illustrating the operation of the third embodiment. [Figure 15] FIG. 11 is a diagram illustrating a first configuration example of a PDCP PDU in the third embodiment. [Figure 16] FIG. 11 is a diagram illustrating a second configuration example of a PDCP PDU in the third embodiment. [Figure 17] FIG. 10 is a diagram illustrating the operation of the fourth embodiment. [Figure 18] FIG. 11 is a diagram illustrating the operation of the fifth embodiment. [Figure 19] FIG. 13 is a diagram illustrating the operation of the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] As described above, when a PDCP header, an RLC header, and a MAC header are added to one PDCP SDU, the proportion of headers in communication between a base station and a user device, i.e., overhead, becomes large. Furthermore, the size of an IP (Internet Protocol) packet corresponding to a PDCP SDU is often small compared to the upper limit of the PDCP SDU size (e.g., 9 kB). For example, the size of an IP packet may be 1.5 kB. This makes it difficult to perform efficient PDCP processing.

[0009] Therefore, an object of the present disclosure is to enable efficient communication in a mobile communication system.

[0010] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0011] (Configuration of a mobile communication system) First, a configuration of a mobile communication system according to an embodiment will be described with reference to Fig. 1 to Fig. 6. Fig. 1 is a diagram showing the configuration of a mobile communication system according to an embodiment. A mobile communication system 1 conforms to the 5th Generation System (5GS) of the 3GPP standard. In the following description, 5GS will be taken as an example, but an LTE (Long Term Evolution) system may also be applied at least in part to the mobile communication system. Furthermore, a sixth generation (6G) system may also be applied at least in part to the mobile communication system.

[0012] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20.

[0013] The UE 100 is a mobile wireless communication device. The UE 100 may be any device that is used by a user. For example, the UE 100 is a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0014] The NG-RAN 10 includes a base station (called a "gNB" in a 5G system) 200. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, etc. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource that performs wireless communication with a UE 100. One cell belongs to one carrier frequency.

[0015] In addition, gNBs can also connect to the Evolved Packet Core (EPC), which is the LTE core network. LTE base stations can also connect to 5GC. LTE base stations and gNBs can also be connected via a base station-to-base station interface.

[0016] The 5GC20 includes an Access and Mobility Management Function (AMF) and a User Plane Function (UPF) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0017] 2 is a diagram showing a configuration of a UE 100 (user equipment) according to an embodiment. The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit .

[0018] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

[0019] The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0020] The control unit 130 performs various controls and processes in the UE 100. Such processes include processes of each layer, which will be described later. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processes by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0021] 3 is a diagram showing the configuration of a gNB 200 (base station) according to one embodiment. The gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0022] The transmission unit 210 performs various transmissions under the control of the control unit 230. The transmission unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0023] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0024] The control unit 230 performs various controls and processes in the gNB 200. Such processes include processes for each layer, which will be described later. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processes by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0025] The backhaul communication unit 240 is connected to neighboring base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF 300 via a base station-core network interface. Note that the gNB is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and both units may be connected via an F1 interface.

[0026] FIG. 4 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0027] The user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0028] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the gNB 200 via a physical channel.

[0029] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of gNB200 via transport channels. The MAC layer of gNB200 includes a scheduler, which determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to UE100.

[0030] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via logical channels.

[0031] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0032] The SDAP layer maps IP flows, which are the units for Quality of Service (QoS) control by the core network, to radio bearers, which are the units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP is not necessary.

[0033] FIG. 5 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

[0034] The protocol stack of the radio interface of the control plane has a Radio Resource Control (RRC) layer and a Non-Access Stratum (NAS) layer instead of the SDAP layer shown in FIG.

[0035] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0036] The NAS layer, which is positioned above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the AMF 300.

[0037] The UE 100 has an application layer and the like in addition to the radio interface protocol.

[0038] FIG. 6 is a diagram illustrating an example of processing at each layer in the protocol stack of the radio interface of the user plane.

[0039] First, we will explain the processing on the transmitting side. The transmitting SDAP entity, which is an entity in the SDAP layer on the transmitting side, receives IP packets to be transmitted to the receiving side as SDAP SDUs, performs SDAP layer transmission processing, and adds an SDAP header to the SDAP SDUs to generate SDAP PDUs and output them to lower layers.

[0040] The transmitting PDCP entity, which is a PDCP layer entity on the transmitting side, receives the SDAP PDU as a PDCP SDU, performs PDCP layer transmission processing, and adds a PDCP header to the PDCP SDU to generate a PDCP PDU and output it to the lower layer.

[0041] The transmitting RLC entity, which is an entity of the RLC layer on the transmitting side, receives the PDCP PDU as an RLC SDU, performs RLC layer transmission processing, and adds an RLC header to the RLC SDU to generate an RLC PDU and output it to the lower layer.

[0042] The transmitting MAC entity, which is a MAC layer entity on the transmitting side, receives the RLC PDU as a MAC SDU, performs MAC layer transmission processing, and adds a MAC header to the MAC SDU to generate a MAC PDU, which is then output to a lower layer.

[0043] Second, we will explain the processing on the receiving side. The receiving MAC entity, which is a MAC layer entity on the receiving side, receives the MAC PDU from the lower layer, performs MAC layer reception processing based on the MAC header, removes the MAC header, and outputs the MAC SDU to the upper layer.

[0044] The receiving RLC entity, which is an entity of the RLC layer on the receiving side, receives the MAC SDU from the lower layer as an RLC PDU, performs RLC layer reception processing based on the RLC header, removes the RLC header, and outputs the RLC SDU to the upper layer.

[0045] The receiving PDCP entity, which is a PDCP layer entity on the receiving side, receives the RLC SDU from the lower layer as a PDCP PDU, performs PDCP layer reception processing based on the PDCP header, removes the PDCP header, and outputs the PDCP SDU to the upper layer.

[0046] The receiving SDAP entity, which is an entity of the SDAP layer on the receiving side, receives PDCP SDUs from a lower layer as SDAP PDUs, performs SDAP layer reception processing based on the SDAP header, removes the SDAP header, and outputs SDAP SDUs (IP packets) to a higher layer.

[0047] (Mobile communication system operation) Next, the operation of the mobile communication system 1 according to the embodiment will be described with reference to Fig. 7 to Fig. 10. The mobile communication system 1 according to the embodiment has a pair of PDCP entities, including a transmitting PDCP entity 50T that transmits a PDCP PDU and a receiving PDCP entity 50R that receives the PDCP PDU (see Fig. 8 and Fig. 9).

[0048] As described above, in communication between the gNB 200 and the UE 100, the transmitting PDCP entity generates a PDCP PDU by adding a PDCP header to a PDCP SDU from an upper layer. Then, the transmitting RLC entity and the transmitting MAC entity add an RLC header and a MAC header, respectively. Since a PDCP header, an RLC header, and a MAC header are added to one PDCP SDU in this way, there is a problem that the proportion of headers in communication between the gNB 200 and the UE 100, i.e., overhead, is large. Furthermore, the size of an IP packet corresponding to a PDCP SDU is often small compared to the upper limit of the PDCP SDU size (e.g., 9 kB). For example, the size of an IP packet may be 1.5 kB. This makes it difficult to perform efficient PDCP processing.

[0049] FIG. 7 is a diagram showing a PDCP PDU according to an embodiment. The transmitting PDCP entity 50T generates a PDCP PDU including a concatenated SDU by performing PDCP concatenation, which concatenates multiple PDCP SDUs. While FIG. 7 shows an example in which the transmitting PDCP entity 50T concatenates three PDCP SDUs, the number of concatenated PDCP SDUs may be two, four, or more. As will be described in detail later, the transmitting PDCP entity 50T may insert a delimiter code between the concatenated PDCP SDUs (see FIGS. 8 and 9). The delimiter code makes it easier for the receiving PDCP entity 50R to separate the PDCP SDUs into individual PDCP SDUs. The receiving PDCP entity 50R performs PDCP separation, which separates multiple PDCP SDUs from the concatenated SDU included in the PDCP PDU.

[0050] Such PDCP concatenation processing can reduce the proportion of headers in communication between the gNB 200 and the UE 100, i.e., reduce overhead. Furthermore, since PDCP processing can be applied to concatenated SDUs with a size close to the upper limit of the PDCP SDU size (e.g., 9 kB), efficient PDCP processing becomes possible.

[0051] Fig. 8 is a diagram showing PDCP connection processing and PDCP separation processing in downlink according to an embodiment. Fig. 9 is a diagram showing PDCP connection processing and PDCP separation processing in uplink according to an embodiment. In Fig. 8 and Fig. 9, an RRC connection is established between the RRC entity of gNB 200 and the RRC entity of UE 100 (i.e., RRC connected state). Note that although Fig. 8 and Fig. 9 show an example in which a delimiter code is used, it is not necessary to use a delimiter code.

[0052] 8, in the downlink, the transmitting PDCP entity 50T of the gNB 200 performs PDCP concatenation processing to concatenate multiple PDCP SDUs, thereby generating a PDCP PDU including the concatenated SDUs, and transmits the PDCP PDU. The receiving PDCP entity 50R of the UE 100 receives the PDCP PDU, and performs PDCP demultiplexing processing to demultiplex the multiple PDCP SDUs from the concatenated SDUs included in the PDCP PDU.

[0053] 9, in the uplink, the transmitting PDCP entity 50T of the UE 100 performs PDCP concatenation processing to concatenate multiple PDCP SDUs, thereby generating a PDCP PDU including the concatenated SDUs, and transmits the PDCP PDU. The receiving PDCP entity 50R of the gNB 200 receives the PDCP PDU and performs PDCP demultiplexing processing to demultiplex the multiple PDCP SDUs from the concatenated SDUs included in the PDCP PDU.

[0054] Although the following description focuses on the application of PDCP concatenation and PDCP separation to the downlink and uplink, they may also be applied to the sidelink, which is a direct link between UEs. In the sidelink, a transmitting PDCP entity 50T of one UE performs PDCP concatenation to concatenate multiple PDCP SDUs, thereby generating a PDCP PDU including the concatenated SDUs, and transmits the PDCP PDU. A receiving PDCP entity 50R of the other UE receives the PDCP PDU and performs PDCP separation to separate the multiple PDCP SDUs from the concatenated SDUs included in the PDCP PDU. When applied to the sidelink, concatenation / separation control information (described below) may be transmitted in a PC5-RRC message. Furthermore, the PDCP concatenation and PDCP separation may also be applied to dual connectivity (DC), multi-connectivity (MC), split bearers, etc.

[0055] 10 is a diagram showing transmission and reception of control information according to one embodiment. A first communication device 21 having one PDCP entity of a pair of PDCP entities transmits control information to a second communication device 22 having the other PDCP entity of the pair (step S1). The control information is used to control at least one of PDCP connection processing and PDCP separation processing. Here, the first communication device 21 is a gNB 200 or a UE 100, and the second communication device 22 is a gNB 200 or a UE 100. In this manner, transmission and reception of control information used to control at least one of PDCP connection processing and PDCP separation processing (hereinafter referred to as "connection / separation control information") enables appropriate control of PDCP connection processing and PDCP separation processing.

[0056] In step S1, the transmitting PDCP entity 50T or the receiving PDCP entity 50R of the first communication device 21 may transmit a PDCP Control PDU containing connection / separation control information to the second communication device 22. PDCP PDUs include PDCP Data PDUs used for transmitting user data and PDCP Control PDUs used for control. PDCP connection processing and PDCP separation processing are applied to PDCP Data PDUs. Note that a PDCP entity is established for each bearer (data bearer). By transmitting connection / separation control information using a PDCP Control PDU, PDCP connection processing and PDCP separation processing can be appropriately controlled for each bearer.

[0057] In step S1, the RRC entity of the first communication device 21 may transmit an RRC message including connection / separation control information to the second communication device 22. For example, the RRC message transmitted from the gNB 200 to the UE 100 may be an RRC Reconfiguration message, which is a UE-dedicated RRC message. The RRC message transmitted from the UE 100 to the gNB 200 may be a UE Assistance Information message and / or a UE Capability Information message. The RRC message including the connection / separation control information may further include a bearer identifier associated with the connection / separation control information. This enables PDCP connection processing and PDCP separation processing to be appropriately controlled for each bearer.

[0058] Alternatively, the connection / separation control information may be included in a MAC Control Element (MAC CE) transmitted and received at the MAC layer. Furthermore, the connection / separation control information may be included in Downlink Control Information (DCI) or Uplink Control Information (UCI) transmitted and received at the PHY layer. The connection / separation control information may be included in a PDCP Control PDU. The connection / separation control information may be included in an RLC Control PDU.

[0059] The first communication device 21 may have a transmitting PDCP entity 50T, and the second communication device 22 may have a receiving PDCP entity 50R. In step S1, the transmitting PDCP entity 50T of the first communication device 21 may transmit a PDCP PDU including connection / separation control information in its PDCP header to the receiving PDCP entity 50R of the second communication device 22. This allows the PDCP connection process and PDCP separation process to be appropriately controlled for each PDCP PDU.

[0060] As described above, the transmitting PDCP entity 50T may generate a PDCP PDU by inserting a delimiter code between each PDCP SDU that constitutes a concatenated SDU. Inserting such a delimiter code makes it easier for the receiving PDCP entity 50R to perform PDCP separation processing. The concatenation / separation control information may include information specifying a delimiter code. This allows any bit string to be specified as the delimiter code. Furthermore, the delimiter code can be changed as needed.

[0061] In one embodiment, the concatenation / separation control information may include information indicating the size of each PDCP SDU constituting the concatenated SDU. This makes it easier for the receiving PDCP entity 50R to perform PDCP separation processing. When transmitting and receiving such concatenation / separation control information, the insertion of a delimiter code may be unnecessary.

[0062] For example, when the first communication device 21 is a gNB 200 having a receiving PDCP entity 50R and the second communication device 22 is a UE 100 having a transmitting PDCP entity 50T, the connection / separation control information may include configuration information for setting the size of each PDCP SDU that can be concatenated by the PDCP concatenation process in the uplink in the UE 100. The connection / separation control information may further include information for setting the maximum size of a concatenated SDU or the maximum size of a PDCP PDU generated using the PDCP concatenation process in the uplink in the UE 100.

[0063] Alternatively, in a case where the first communication device 21 has a transmitting PDCP entity 50T and the second communication device 22 has a receiving PDCP entity 50R, the transmitting PDCP entity 50T of the first communication device 21 may generate a PDCP PDU by adding to the concatenated SDU a PDCP header that includes, as concatenation / separation control information, information indicating the size of each PDCP SDU that constitutes the concatenated SDU.

[0064] In one embodiment, the connection / separation control information may include information for starting or terminating the PDCP connection or PDCP separation process. This allows the PDCP connection and PDCP separation processes to be turned on or off (activated or deactivated) depending on the situation. For example, this allows the PDCP connection and PDCP separation processes to be temporarily turned off during a period in which RLC segmentation is being performed in the RLC layer.

[0065] For example, when the first communication device 21 is a gNB 200 having a transmitting PDCP entity 50T and the second communication device 22 is a UE 100 having a receiving PDCP entity 50R, the connection / separation control information may include information for setting downlink PDCP separation processing in the UE 100. Furthermore, for example, the connection / separation control information may include information for activating downlink PDCP separation processing.

[0066] When the first communication device 21 is a gNB 200 having a transmitting PDCP entity 50T and the second communication device 22 is a UE 100 having a receiving PDCP entity 50R, the connection / separation control information may include information for releasing the setting of PDCP separation processing in the downlink, and may also include information for deactivating PDCP separation processing in the downlink.

[0067] When the first communication device 21 is a gNB 200 having a receiving PDCP entity 50R and the second communication device 22 is a UE 100 having a transmitting PDCP entity 50T, the connection / separation control information may include information for setting uplink PDCP connection processing in the UE 100. The connection / separation control information may also include information for activating uplink PDCP connection processing.

[0068] When the first communication device 21 is a gNB 200 having a receiving PDCP entity 50R and the second communication device 22 is a UE 100 having a transmitting PDCP entity 50T, the connection / separation control information may include information for releasing the setting of the PDCP connection process in the uplink, and may also include information for deactivating the PDCP connection process in the uplink.

[0069] When the first communication device 21 is a UE 100 having a transmitting PDCP entity 50T and the second communication device 22 is a gNB 200 having a receiving PDCP entity 50R, the connection / separation control information may include information indicating the decision made by the UE 100 to activate or deactivate PDCP connection processing in the uplink.

[0070] (Example) Next, based on the above-described embodiment, first to sixth examples will be described. These examples are not limited to being implemented independently, but may be implemented by combining two or more examples. Furthermore, in the operation flow of each of the following examples, it is not necessary to execute all steps, and only some of the steps may be executed.

[0071] (1) First Example The first embodiment is an embodiment relating to the above-mentioned delimiter code. Fig. 11 is a diagram showing the delimiter code according to the first embodiment.

[0072] In the example shown in Fig. 11, the transmitting PDCP entity 50T generates a PDCP PDU including concatenated SDUs by performing PDCP concatenation to concatenate three PDCP SDUs (PDCP SDUs #1 to #3). In the first embodiment, the transmitting PDCP entity 50T inserts delimiter codes #2 and #3 between the PDCP SDUs to be concatenated. The transmitting PDCP entity 50T may insert delimiter code #1 at the beginning of the concatenated SDU, i.e., at the beginning of the payload portion of the PDCP PDU. The transmitting PDCP entity 50T may insert delimiter code #4 at the end of the concatenated SDU, i.e., at the end of the payload portion of the PDCP PDU. However, the delimiter code #1 at the beginning and the delimiter code #4 at the end are not necessary.

[0073] Each delimiter code may be any bit string that is recognized in advance by the transmitting PDCP entity 50T and the receiving PDCP entity 50R. For example, "0000 0000 0000 0000" may be used as the delimiter code. However, this bit length (16 bits) or simply a string of "0"s may coincidentally match the bit string that constitutes the PDCP SDU, which may result in an erroneous determination by the receiving PDCP entity 50R.

[0074] Each delimiter code may be a combination of an arbitrary bit string and a checksum that are recognized in advance by the transmitting PDCP entity 50T and the receiving PDCP entity 50R. For example, in "0101 0011 1101 0101," the last four bits are the checksum section, and the rest is an arbitrary bit string. 0101 ("5" in decimal) + 0011 ("3" in decimal) + 1101 ("13" in decimal) = 10101 ("21" in decimal), but the lower four bits of 10101 ("21" in decimal) are taken to make "0101" the checksum section. Such a checksum is a checksum of the delimiter code alone. Alternatively, the checksum may be a checksum of the entire PDCP SDU. For example, delimiter code #2 can be the checksum of PDCP SDU #1, delimiter code #3 can be the checksum of PDCP SDU #2, and delimiter code #4 can be the checksum of PDCP SDU #3. Alternatively, the checksum may be a checksum for the PDCP SDU and (part of) the delimiter code. That is, the delimiter code is composed of a fixed bit string portion and a checksum portion. For example, delimiter code #2 (checksum portion of delimiter code #2) can be the checksum of PDCP SDU #1 and delimiter code #2 (fixed bit string portion). Delimiter code #3 (checksum portion of delimiter code #3) can be the checksum of PDCP SDU #2 and delimiter code #3 (fixed bit string portion). Delimiter code #4 (checksum portion of delimiter code #4) can be the checksum of PDCP SDU #3 and delimiter code #4 (fixed bit string portion). However, even when using such a method of configuring delimiter codes, there is a possibility that they may coincidentally match the bit strings that make up the PDCP SDU.

[0075] The delimiter code may be an escape representation (escape code) like that used in PPP (Point-to-Point Protocol). With escape codes, octets from 0x40 to 0xff, excluding 0x00 to 0x1f and 0x5e, are sent with 0x7d followed by the XOR value of the original value and 0x20. For example, if the delimiter code is fixed to 0x11, 0x11 in the transmitted data is converted to 0x7d and 0x31 before being sent. This allows end markers and the like to also be fixed codes. The receiving side also performs the reverse operation.

[0076] Fig. 12 is a diagram showing the operation of the first embodiment. In Fig. 12, the first communication device 21 is a gNB 200 or a UE 100 having a transmitting PDCP entity 50T. In Fig. 12, the second communication device 22 is a gNB 200 or a UE 100 having a receiving PDCP entity 50R.

[0077] In step S101, a bit string of a delimiter code (and / or end marker) is specified. The bit string of the delimiter code (and / or end marker) may be a fixed value defined in a technical specification. The bit string of the delimiter code (and / or end marker) may be specified by the gNB 200 to the UE 100. The bit string of the delimiter code (and / or end marker) may be specified by the UE 100 to the gNB 200. The bit string of the delimiter code (and / or end marker) may be specified by the transmitting PDCP entity 50T to the receiving PDCP entity 50R. The bit string of the delimiter code (and / or end marker) may be specified by the receiving PDCP entity 50R to the transmitting PDCP entity 50T.

[0078] In step S102, the transmitting PDCP entity 50T determines whether or not there is a bit sequence that matches a specified delimiter code in the multiple PDCP SDUs to be concatenated. Specifically, the transmitting PDCP entity 50T first receives the multiple PDCP SDUs to be concatenated from an upper layer. At this point, the transmitting PDCP entity 50T may perform header compression processing on each PDCP SDU (individually). Next, the transmitting PDCP entity 50T checks the bit sequence of the multiple PDCP SDUs to determine whether or not it matches a specified delimiter code.

[0079] If the answer is YES in step S102 (i.e., if they match), in step S103, the transmitting PDCP entity 50T determines a bit string that is not included in the multiple PDCP SDUs as a new delimiter code (i.e., the transmitting PDCP entity 50T re-specifies the non-matching delimiter code). The transmitting PDCP entity 50T may notify the receiving PDCP entity 50R of the re-specified delimiter code, for example, by using a PDCP Control PDU (step S104). The transmitting PDCP entity 50T may notify the receiving PDCP entity 50R of the delimiter code only if the delimiter code has been re-specified, without making this notification if the delimiter code has not been re-specified. Alternatively, the transmitting PDCP entity 50T may notify the receiving PDCP entity 50R of the delimiter code to be used in the PDCP PDU (PDCP Data PDU) by using the header of the PDCP PDU, regardless of whether the delimiter code has been re-specified.

[0080] In step S105, the transmitting PDCP entity 50T concatenates PDCP SDUs using the designated delimiter code (redesignated delimiter code). As described above, the transmitting PDCP entity 50T generates a concatenated SDU such as "delimiter code+PDCP SDU#1+delimiter code+PDCP SDU#2+delimiter code."

[0081] In step S106, the transmitting PDCP entity 50T performs predetermined PDCP processing on the concatenated SDU to generate a PDCP PDU. The predetermined PDCP processing may, for example, perform integrity protection, ciphering, and attach a PDCP header in this order. The transmitting PDCP entity 50T may include information indicating the number of delimiter code bits in the PDCP header attached to the concatenated SDU. The transmitting PDCP entity 50T outputs the PDCP PDU to the lower layer (RLC).

[0082] In step S107, the first communication device 21 transmits the PDCP PDU to the second communication device 22. The second communication device 22 receives the PDCP PDU.

[0083] In step S108, the receiving PDCP entity 50R receives the PDCP PDU from the lower layer (RLC) and performs predetermined PDCP processing on the PDCP PDU. The predetermined PDCP processing includes deciphering, integrity verification, and reordering / duplication discarding in this order. The predetermined PDCP processing includes removing the PDCP header.

[0084] In step S109, the receiving PDCP entity 50R removes the delimiter codes from the concatenated SDUs and extracts each concatenated PDCP SDU. The receiving PDCP entity 50R may perform header decompression processing on each extracted PDCP SDU. Here, the receiving PDCP entity 50R may recognize the bit string of the delimiter code based on the first and / or last delimiter code. If the PDCP header contains information about the number of bits of the delimiter code, the receiving PDCP entity 50R may recognize the delimiter code by extracting that number of bits from after the PDCP header and / or from the end of the PDCP PDU. The receiving PDCP entity 50R outputs each PDCP SDU to an upper layer.

[0085] (2) Second Example In the second embodiment, PDCP separation processing is enabled by specifying the size of concatenable PDCP SDUs instead of the delimiter code described above. While the description here assumes uplink communication, similar operations may also be performed in downlink communication.

[0086] 13 is a diagram illustrating the operation of Example 2. It is assumed that the UE 100 has a transmitting PDCP entity 50T, and the gNB 200 has a receiving PDCP entity 50R.

[0087] In step S201, the size of PDCP SDUs that can be concatenated is specified. The PDCP SDU size may be a fixed value defined in a technical specification. The PDCP SDU size may be specified to the UE 100 by the gNB 200. The PDCP SDU size may be specified to the gNB 200 by the UE 100. The PDCP SDU size may be specified to the receiving PDCP entity 50R by the transmitting PDCP entity 50T. The PDCP SDU size may be specified to the transmitting PDCP entity 50T by the receiving PDCP entity 50R. Information indicating the PDCP SDU size may be included in an RRC message or a PDCP Control PDU. The information indicating the PDCP SDU size may be associated with a bearer identifier. That is, the PDCP SDU size may be set for each bearer.

[0088] The concatenable size of PDCP SDUs may be a single value (for example, 1.5 kB) and / or a range of values (for example, 1.0 kB to 1.5 kB). In the case of a range, the delimiter code described above may be required.

[0089] In addition, the maximum size of a concatenated SDU may be specified along with the size of the concatenated PDCP SDU, which may be the maximum size of the payload of a PDCP PDU.

[0090] In step S202, the transmitting PDCP entity 50T receives a PDCP SDU from an upper layer and determines whether the size of the PDCP SDU matches a specified PDCP SDU size.

[0091] If the size of the PDCP SDU matches the specified PDCP SDU size, the transmitting PDCP entity 50T performs PDCP concatenation processing in step S203. When performing PDCP concatenation processing, the transmitting PDCP entity 50T concatenates the PDCP SDU to the PDCP SDU received immediately before. If the sum of the size of the concatenated SDU and the specified PDCP SDU size is equal to or greater than the maximum size of the concatenated SDU (i.e., if the transmitting PDCP entity 50T cannot concatenate the PDCP SDU even when it receives the next PDCP SDU), the transmitting PDCP entity 50T terminates the PDCP concatenation processing. Then, the transmitting PDCP entity 50T performs predetermined PDCP processing and passes the PDCP PDU to the lower layer (step S204).

[0092] In step S202, if the size of the PDCP SDU does not match the specified PDCP SDU size, the transmitting PDCP entity 50T may complete the PDCP concatenation process without concatenating the PDCP SDU and perform the PDCP transmission process. This means that when a PDCP SDU that cannot be concatenated arrives in order to perform in-order delivery, the PDCP PDU including the PDCP SDUs that have been concatenated up to that point is passed to the lower layer.

[0093] Alternatively, if the size of the PDCP SDU does not match the specified PDCP SDU size in step S202, the transmitting PDCP entity 50T may continue the PDCP concatenation process without concatenating the PDCP SDU and perform the PDCP concatenation process on the next PDCP SDU. This increases the size of each PDCP PDU to improve processing efficiency while allowing out-of-order delivery.

[0094] In step S202, if the PDCP SDU is smaller than the specified PDCP SDU size, the transmitting PDCP entity 50T may add padding bits to the PDCP SDU to make it match the specified PDCP SDU size before performing PDCP concatenation processing.

[0095] In step S205, the UE 100 transmits the PDCP PDU to the gNB 200. The gNB 200 receives the PDCP PDU.

[0096] In step S206, the receiving PDCP entity 50R of the gNB 200 performs PDCP receiving processing.

[0097] In step S207, the receiving PDCP entity 50R performs PDCP separation processing. For example, the receiving PDCP entity 50R removes the PDCP header, divides the payload portion (concatenated SDU) for each specified PDCP SDU size, and extracts multiple PDCP SDUs. The receiving PDCP entity 50R then outputs the multiple PDCP SDUs to an upper layer. Here, the receiving PDCP entity 50R may output the multiple PDCP SDUs to the upper layer in the order in which they were concatenated in the payload portion (i.e., in-order delivery).

[0098] Note that the gNB 200 may configure the UE 100 to perform the PDCP connection process in order (in-order). Such a configuration may be notified from the receiving PDCP entity 50R to the transmitting PDCP entity 50T. Also, such a configuration may be notified from the transmitting PDCP entity 50T to the receiving PDCP entity 50R.

[0099] (3) Third Example The third embodiment is an embodiment in which the size of each PDCP SDU constituting a concatenated SDU included in a PDCP PDU is notified by the PDCP header of the PDCP PDU.

[0100] Fig. 14 is a diagram showing the operation of Example 3. In Fig. 14, the first communication device 21 is a gNB 200 or a UE 100 having a transmitting PDCP entity 50T, and the second communication device 22 is a gNB 200 or a UE 100 having a receiving PDCP entity 50R.

[0101] In step S301, the transmitting PDCP entity 50T performs a PDCP concatenation process, where the transmitting PDCP entity 50T may store the size of each PDCP SDU to be concatenated.

[0102] In step S302, the transmitting PDCP entity 50T generates SDU size information indicating the size of each PDCP SDU to be concatenated, and places the SDU size information in the PDCP header.

[0103] If the concatenated PDCP SDUs are of the same size, the SDU size information may include only one size. To make the concatenated PDCP SDUs of the same size, the transmitting PDCP entity 50T may add padding bits to PDCP SDUs smaller than the size before concatenating them.

[0104] On the other hand, if the concatenated PDCP SDUs are of different sizes, the SDU size information may include information on the size of each PDCP SDU. In this case, the order of the size information in the header may match the order of the PDCP SDUs in the payload. This allows the receiving PDCP entity 50R to determine the correspondence between the size information and the corresponding PDCP SDUs based on the order of arrangement.

[0105] In step S303, the transmitting PDCP entity 50T attaches a PDCP header including the SDU size information generated in step S302 to the concatenated SDU and performs PDCP transmission processing. The transmitting PDCP entity 50T may include, in the PDCP header, information indicating that the PDCP concatenation processing has been performed on the PDCP PDU. The transmitting PDCP entity 50T may include, in the PDCP header, information indicating the number of PDCP SDUs that make up the concatenated SDU.

[0106] In step S304, the first communication device 21 transmits the PDCP PDU to the second communication device 22. The second communication device 22 receives the PDCP PDU.

[0107] In step S305, the receiving PDCP entity 50R receives the PDCP PDU from the lower layer and performs PDCP reception processing.

[0108] In step S306, the receiving PDCP entity 50R performs PDCP separation processing based on the SDU size information included in the header of the PDCP PDU. Specifically, the receiving PDCP entity 50R obtains the SDU size information from the header of the PDCP PDU, removes the header, and then divides the payload based on the SDU size information. The receiving PDCP entity 50R then outputs each of the divided PDCP SDUs to an upper layer.

[0109] 15 is a diagram showing a first configuration example of a PDCP PDU in Example 3. The first configuration example can be applied when the sizes of the PDCP SDUs that make up a concatenated SDU are the same.

[0110] In FIG. 15, if the value set in the "C" field is "1," it indicates that the PDCP PDU has undergone PDCP concatenation processing. In this case, a "Size" field is inserted. The "Size" field indicates the size of the PDCP SDU. The value set in the "Size" field may be an index indicating the size of the PDCP SDU. The index refers to a table of PDCP SDU sizes. For example, the correspondence is as follows: "0000 0000": 100 bytes, "0000 0001": 200 bytes, ..., "1111 1111": 1500 bytes. The "Size" field may be located before "Data" (stored in the PDCP header) or at the end of the PDCP PDU (i.e., the "Size" field may be located after "MAC-I").

[0111] 16 is a diagram showing a second configuration example of a PDCP PDU in Example 3. The second configuration example can be applied when the sizes of the PDCP SDUs constituting a concatenated SDU are at least partially different.

[0112] In FIG. 16, the "C" field is the same as in the first configuration example described above. When the value set in the "M" field is "1," this indicates that each size of PDCP SDU is notified. The "List size" field indicates the number of "Sizes" (or the number of PDCP SDUs). The value set in the "List size" field may be an index indicating the number. The index refers to a table of the number. For example, "0000 0000" corresponds to 2, "0000 0001" corresponds to 3, ..., "1111 1111" corresponds to n. The "Size" field is the same as in the first configuration example described above. The "List size" field and / or the "Size" field may be located before "Data" (stored in the PDCP header) or at the end of the PDCP PDU (i.e., the "List size" field and / or the "Size" field may be located after "MAC-I").

[0113] (4) Fourth Example The fourth embodiment is an embodiment in which the gNB 200 controls the PDCP connection / separation process in the downlink. Fig. 17 is a diagram showing the operation of the fourth embodiment. It is assumed that the gNB 200 has a transmitting PDCP entity 50T, and the UE 100 has a receiving PDCP entity 50R.

[0114] In step S401, the UE 100 transmits capability information (e.g., a UE Capability Information message) indicating that the UE 100 supports downlink PDCP separation processing to the gNB 200. Such information may be information indicating that downlink PDCP connection processing is permitted. The gNB 200 may determine to perform downlink PDCP connection processing based on the information.

[0115] In step S402, the gNB 200 performs configuration related to downlink PDCP demultiplexing processing, for example, by an RRC message or a PDCP Control PDU transmitted to the UE 100. Such configuration includes at least one of the following: the size (or size range) of each PDCP SDU to be concatenated, the maximum size of a PDCP PDU or its payload portion (maximum size of concatenated SDUs), and the bearer ID of the bearer for which PDCP concatenation / demultiplexing processing is performed.

[0116] In step S403, the gNB 200 transmits instruction information to the UE 100, for example, by an RRC message or a PDCP Control PDU transmitted to the UE 100, instructing the UE 100 to activate downlink PDCP separation processing. Such instruction information may be information instructing the UE 100 to start downlink PDCP combining processing. The instruction information may include the bearer ID of the target bearer. However, step S403 is not essential, and the configuration in step S402 may also serve as activation (standby instruction). That is, the gNB 200 may force the UE 100 to enter standby mode by the configuration in step S402, even without issuing the standby instruction. In this case, the configuration information in step S402 may include an information element indicating the activation. The UE 100 may recognize that there is a possibility that it will receive PDCP PDUs that have undergone PDCP concatenation processing if the configuration is performed.

[0117] Note that the gNB 200 may decide to start the PDCP connection / separation process depending on whether the radio resources of its own cell are not congested and / or whether the radio environment between the UE 100 and the gNB 200 is good. The radio environment can be known, for example, from a measurement report from the UE 100 and / or gNB measurements of a UL signal from the UE 100, and the radio environment may be represented by, for example, RSRP, RSRQ, or SINR.

[0118] In step S404, the transmitting PDCP entity 50T of the gNB 200 performs downlink PDCP connection processing and PDCP transmission processing.

[0119] In step S405, the gNB 200 transmits the PDCP PDU to the UE 100. The UE 100 receives the PDCP PDU.

[0120] In step S406, the receiving-side PDCP entity 50R of the UE 100 performs downlink PDCP reception processing and PDCP separation processing, thereby outputting each PDCP SDU to an upper layer.

[0121] Thereafter, in step S407, the gNB 200 may transmit, to the UE 100, instruction information instructing the UE 100 to deactivate downlink PDCP separation processing, for example, by an RRC message or a PDCP Control PDU transmitted to the UE 100. The instruction information may include a bearer ID of the target bearer. Such instruction information may be release instruction information for releasing the setting made in step S402. In response to receiving such instruction information, the UE 100 stops (ends) downlink PDCP separation processing.

[0122] In addition, gNB200 may decide to terminate the PDCP connection / separation process depending on whether the radio resources of its own cell are congested and / or whether the radio environment between UE100 and gNB200 is poor.

[0123] (5) Fifth Example The fifth embodiment is an embodiment in which the gNB 200 controls the PDCP connection / separation process in the uplink. Fig. 18 is a diagram showing the operation of the fifth embodiment. It is assumed that the UE 100 has a transmitting PDCP entity 50T, and the gNB 200 has a receiving PDCP entity 50R.

[0124] In step S501, the UE 100 transmits capability information (e.g., a UE Capability Information message) indicating that the UE 100 supports uplink PDCP connection processing to the gNB 200. Based on the information, the gNB 200 may decide to cause the UE 100 to perform uplink PDCP connection processing.

[0125] In step S502, the gNB 200 performs configuration related to uplink PDCP connection processing, for example, by an RRC message or a PDCP Control PDU transmitted to the UE 100. Such configuration includes at least one of the following: the size (or size range) of each PDCP SDU to be connected, the maximum size of a PDCP PDU or its payload (maximum size of a connected SDU), and the bearer ID of the bearer for which PDCP connection / separation processing is performed.

[0126] In step S503, the gNB 200 transmits instruction information to the UE 100, for example, by an RRC message or a PDCP Control PDU transmitted to the UE 100, instructing the UE 100 to activate uplink PDCP connection processing. The instruction information may include the bearer ID of the target bearer. However, step S503 is not essential, and the setting in step S502 may also serve as the activation (standby instruction). In other words, the gNB 200 may force the UE 100 to start PDCP connection processing by the setting in step S502, even without issuing the standby instruction. In this case, the setting information in step S502 may include an information element indicating the activation. The UE 100 may recognize that there is a possibility that it will receive a PDCP PDU that has undergone PDCP connection processing if the setting is performed.

[0127] In addition, gNB200 may decide to start the PDCP connection / separation process depending on whether the radio resources of its own cell are not congested and / or whether the radio environment between UE100 and gNB200 is good.

[0128] In step S504, the transmitting PDCP entity 50T of the UE 100 performs uplink PDCP connection processing and PDCP transmission processing.

[0129] In step S505, the UE 100 transmits the PDCP PDU to the gNB200 The gNB200 receives the PDCP PDU.

[0130] In step S506, the receiving PDCP entity 50R of the gNB 200 performs uplink PDCP reception processing and PDCP separation processing, thereby outputting each PDCP SDU to an upper layer.

[0131] Thereafter, in step S507, the gNB 200 may transmit, to the UE 100, instruction information instructing the UE 100 to deactivate the uplink PDCP connection process, for example, by an RRC message or a PDCP Control PDU transmitted to the UE 100. The instruction information may include a bearer ID of the target bearer. Such instruction information may be release instruction information for releasing the setup in step S502. In response to receiving such instruction information, the UE 100 stops (terminates) the uplink PDCP connection process.

[0132] In addition, gNB200 may decide to terminate the PDCP connection / separation process depending on whether the radio resources of its own cell are congested and / or whether the radio environment between UE100 and gNB200 is poor.

[0133] (6) Sixth Example The sixth embodiment is an embodiment for activating and deactivating the PDCP connection and separation process in the uplink at the initiative of the UE. Fig. 19 is a diagram showing the operation of the sixth embodiment. It is assumed that the UE 100 has a transmitting PDCP entity 50T, and the gNB 200 has a receiving PDCP entity 50R.

[0134] In FIG. 19, the processes of steps S601, S602, S604, S605, and S606 are the same as the above-described steps S501, S502, S504, S505, and S506, so only steps S603 and S607 will be described.

[0135] In step S603, the UE 100 determines to turn on (activate) the uplink PDCP connection process in accordance with a predetermined condition, and transmits activation information to the gNB 200. The predetermined condition may be, for example, a condition that the radio environment is good. Alternatively, the predetermined condition may be, for example, a condition that RLC segmentation does not occur frequently. Such a condition determination may be made by comparison with a threshold. The threshold may be set by the gNB 200 to the UE 100. The activation information may be transmitted by an RRC message or a PDCP Control PDU. The activation information may include a bearer ID of a target bearer.

[0136] In step S607, the UE 100 determines to turn off (deactivate) the uplink PDCP connectivity process in accordance with a predetermined condition, and transmits deactivation information to the gNB 200. The predetermined condition may be, for example, a condition that the radio environment is poor. Alternatively, the predetermined condition may be, for example, a condition that RLC segmentation occurs frequently. Such a condition determination may be made by comparison with a threshold. The threshold may be set by the gNB 200 to the UE 100. The deactivation information may be transmitted by an RRC message or a PDCP Control PDU. The deactivation information may include a bearer ID of the target bearer.

[0137] In the sixth embodiment, an example has been described in which the UE takes the initiative in activating and deactivating the PDCP connection / separation process in the uplink. However, a modified example is also possible in which the UE 100 takes the initiative in activating and deactivating the PDCP connection process in the gNB 200 in the downlink. For example, a UE 100 having such capability may transmit capability information (e.g., a UE Capability Information message) indicating that the UE 100 has the capability to the gNB 200. In such a modified example, the "uplink PDCP connection process" in the description of steps S603 and S607 above should be read as "downlink PDCP connection process."

[0138] (Other embodiments) In the above-described embodiment and example, the UE 100 may receive a PDCP PDU transmitted by broadcast or multicast from the gNB 200 in an RRC idle state or an RRC inactive state. Such a PDCP PDU may be a type of MBS (Multicast Broadcast Service) data. The gNB 200 may apply the above-described PDCP connection process to such a PDCP PDU. The UE 100 may apply the above-described PDCP connection process to such a PDCP PDU. The connection / separation control information transmitted from the gNB 200 to the UE 100 may be information included in a system information message (SIB: System Information Block), which is an RRC message broadcast by the gNB 200.

[0139] In the above-described embodiments and examples, the PDCP connection process and the PDCP separation process have been mainly described as being applied to the downlink, uplink, and sidelink. However, the PDCP connection process and the PDCP separation process may also be applied to links via a WLAN (Wireless Local Area Network). For example, the PDCP connection process and the PDCP separation process may be applied to a protocol stack in which an adaptation layer is placed below the PDCP layer, and the WLAN MAC layer and PHY layer are placed below the adaptation layer.

[0140] The above-mentioned operational flows are not limited to being implemented independently, but can also be implemented by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow.

[0141] In the above-described embodiment and example, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB) or a 6G base station. The base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU (Distributed Unit) of the IAB node. The user equipment may also be an MT (Mobile Termination) of the IAB node.

[0142] A program may be provided that causes a computer to execute each process performed by UE100 or gNB200. The program may be recorded on a computer-readable medium. The computer-readable medium can be used to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a part of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0143] As used in this disclosure, the terms "based on" and "depending on" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "at least in part on." Furthermore, "obtain" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may also mean including only the listed items or including additional items in addition to the listed items. Furthermore, as used in this disclosure, the term "or" is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, reference to first and second elements does not imply that only two elements may be employed therein or that the first element must precede the second element in some manner. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0144] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention.

[0145] This application claims priority to Japanese Patent Application No. 2021-115339 (filed July 12, 2021), the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0146] 1: Mobile communication system 21: First communication device 22: Second communication device 50R: Receiving PDCP entity 50T: Transmitting PDCP entity 100:UE 110: Receiving unit 120: Transmitter 130: Control unit 200 :gNB 210: Transmission unit 220: Receiving unit 230: Control unit 240: Backhaul communication unit

Claims

1. A communication method used in a mobile communication system having a pair of PDCP entities, the pair including a transmitting PDCP entity that transmits a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a receiving PDCP entity that receives the PDCP PDU, comprising: The transmitting PDCP entity performs a PDCP concatenation process to concatenate a plurality of PDCP Service Data Units (SDUs), thereby generating the PDCP PDU including the concatenated SDUs; performing a PDCP separation process by the receiving PDCP entity to separate the plurality of PDCP SDUs from the concatenated SDU included in the PDCP PDU; transmitting control information used to control at least one of the PDCP connection process and the PDCP separation process from a first communication device having one of the pair of PDCP entities to a second communication device having the other of the pair of PDCP entities; generating the PDCP PDU, inserting a delimiter code between each of the PDCP SDUs constituting the concatenated SDU; and determining a bit string not included in the plurality of PDCP SDUs as a new delimiter code when a bit string matching the designated delimiter code is present in the plurality of PDCP SDUs. Communication method.

2. The transmitting step includes transmitting a PDCP Control PDU including the control information from the transmitting PDCP entity or the receiving PDCP entity. The communication method according to claim 1 .

3. The transmitting includes transmitting an RRC message including the control information. The communication method according to claim 1 .

4. The transmitting includes transmitting the RRC message further including a bearer identifier associated with the control information. The communication method according to claim 3 .

5. the first communication device has the transmitting PDCP entity; the second communication device has the receiving PDCP entity; The transmitting step includes transmitting the PDCP PDU, the PDCP PDU including the control information in a PDCP header, by the transmitting PDCP entity. The communication method according to claim 1 .

6. The control information includes information specifying the delimiter code. The communication method according to claim 1 .

7. A communication method used in a mobile communication system having a pair of PDCP entities, the pair including a transmitting-side PDCP entity that transmits a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a receiving-side PDCP entity that receives the PDCP PDU, comprising: The transmitting PDCP entity performs a PDCP concatenation process to concatenate a plurality of PDCP Service Data Units (SDUs), thereby generating the PDCP PDU including the concatenated SDUs; performing a PDCP separation process by the receiving PDCP entity to separate the plurality of PDCP SDUs from the concatenated SDU included in the PDCP PDU; transmitting control information used to control at least one of the PDCP connection process and the PDCP separation process from a first communication device having one of the pair of PDCP entities to a second communication device having the other of the pair of PDCP entities; the first communication device is a network node having the receiving PDCP entity; the second communication device is a user equipment having the transmitting PDCP entity; The control information includes configuration information for configuring the size of each PDCP SDU that can be concatenated by the PDCP concatenation procedure in the uplink in the user equipment. Communication method.

8. The control information further includes information for configuring the user equipment with a maximum size of the concatenated SDU or a maximum size of the PDCP PDU generated using the PDCP concatenation procedure in uplink. The communication method according to claim 7.

9. the first communication device has the transmitting PDCP entity; the second communication device has the receiving PDCP entity; Generating the PDCP PDU includes adding the PDCP header, which includes information indicating the size of each PDCP SDU constituting the concatenated SDU, to the concatenated SDU. The communication method according to claim 7.

10. A communication device used in a mobile communication system having a pair of PDCP entities, the pair including a transmitting-side PDCP entity that transmits a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a receiving-side PDCP entity that receives the PDCP PDU, comprising: a control unit having either the transmitting PDCP entity or the receiving PDCP entity; The transmitting PDCP entity: performing a PDCP concatenation process for concatenating a plurality of PDCP Service Data Units (SDUs) to generate a PDCP PDU including the concatenated SDUs; inserting a delimiter code between each PDCP SDU constituting the concatenated SDU; If there is a bit string in the plurality of PDCP SDUs that matches the designated delimiter code, determining a bit string that is not included in the plurality of PDCP SDUs as a new delimiter code; the receiving PDCP entity performs a PDCP separation process to separate the plurality of PDCP SDUs from the concatenated SDU included in the PDCP PDU; The control unit transmits control information used to control at least one of the PDCP connection process and the PDCP separation process to another communication device. Communication equipment.

11. A network node used in a mobile communication system having a pair of PDCP entities, the pair consisting of a transmitting-side PDCP entity that transmits a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a receiving-side PDCP entity that receives the PDCP PDU, comprising: a control unit having the receiving-side PDCP entity, the transmitting PDCP entity performs a PDCP concatenation process to concatenate a plurality of PDCP Service Data Units (SDUs) to generate the PDCP PDU including the concatenated SDUs; the receiving PDCP entity performs a PDCP separation process to separate the plurality of PDCP SDUs from the concatenated SDU included in the PDCP PDU; The control unit transmits control information used to control at least one of the PDCP connection process and the PDCP separation process to a user equipment having the transmitting PDCP entity; The control information includes configuration information for configuring the size of each PDCP SDU that can be concatenated by the PDCP concatenation procedure in the uplink in the user equipment. Network node.

12. A user equipment used in a mobile communication system having a pair of PDCP entities, the pair consisting of a transmitting-side PDCP entity that transmits a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a receiving-side PDCP entity that receives the PDCP PDU, the user equipment comprising: a control unit having the transmitting-side PDCP entity, the transmitting PDCP entity performs a PDCP concatenation process to concatenate a plurality of PDCP Service Data Units (SDUs) to generate the PDCP PDU including the concatenated SDUs; the receiving PDCP entity performs a PDCP separation process to separate the plurality of PDCP SDUs from the concatenated SDU included in the PDCP PDU; The control unit receives control information used to control at least one of the PDCP connection process and the PDCP separation process from a network node having the receiving side PDCP entity; The control information includes configuration information for configuring the size of each PDCP SDU that can be concatenated by the PDCP concatenation procedure in the uplink in the user equipment. User equipment.

13. A chipset for a communication device used in a mobile communication system having a pair of PDCP entities, the pair including a transmitting-side PDCP entity that transmits a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a receiving-side PDCP entity that receives the PDCP PDU, the chipset comprising: a process in which the transmitting PDCP entity performs a PDCP concatenation process of concatenating a plurality of PDCP SDUs (Service Data Units) to generate the PDCP PDU including the concatenated SDUs; a process in which the transmitting PDCP entity inserts a delimiter code between each PDCP SDU constituting the concatenated SDU; a process in which, when a bit sequence matching a designated delimiter code is present in the plurality of PDCP SDUs, the transmitting PDCP entity determines a bit sequence not included in the plurality of PDCP SDUs as a new delimiter code; a PDCP separation process performed by the receiving PDCP entity to separate the plurality of PDCP SDUs from the concatenated SDU included in the PDCP PDU; and transmitting control information used to control at least one of the PDCP connection process and the PDCP separation process to another communication device. Chipset.

14. A chipset for a user device used in a mobile communication system having a pair of PDCP entities, the pair consisting of a transmitting-side PDCP entity that transmits a PDCP (Packet Data Convergence Protocol) PDU (Protocol Data Unit) and a receiving-side PDCP entity that receives the PDCP PDU, the chipset comprising: a process in which the transmitting PDCP entity performs a PDCP concatenation process of concatenating a plurality of PDCP SDUs (Service Data Units) to generate the PDCP PDU including the concatenated SDUs; a PDCP separation process performed by the receiving PDCP entity to separate the plurality of PDCP SDUs from the concatenated SDU included in the PDCP PDU; receiving control information used to control at least one of the PDCP connection procedure and the PDCP separation procedure from a network node having the receiving PDCP entity; The control information includes configuration information for configuring the size of each PDCP SDU that can be concatenated by the PDCP concatenation procedure in the uplink in the user equipment. Chipset.

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