Communication device, wireless communication system, control method, and program

Abstract

A communication device according to one embodiment of the present disclosure has a transmission means for transmitting, to a base station, a medium access control (MAC) control element (CE) which includes: a field indicating information relating to a buffer amount of a data unit buffered in the communication device; a field indicating information relating to remaining time until the data unit is discarded; a field indicating information relating to an LCG (logical channel group); and a field capable of indicating that, in one LCG, there are a plurality of field groups including the field indicating the information relating to the buffer amount and the field indicating the information relating to the remaining time until the data unit is discarded.

Description

Communication device, wireless communication system, control method and program

[0001] This disclosure relates to communication devices, wireless communication systems, control methods, and programs.

[0002] Cellular communication standards are being developed within the Third Generation Partnership Project (3GPP®). Within the 3GPP cellular communication standards (hereinafter referred to as "3GPP standards"), the standardization of XR (extended reality), representing virtual reality technology, is underway. Furthermore, Technical Report (TR) 26.928 describes various use cases related to XR.

[0003] In a 5G network, base stations (hereinafter also referred to as gNBs (gNodeBs)) are responsible for scheduling uplink (UL) traffic (hereinafter referred to as UL scheduling). In UL scheduling, the gNB allocates radio resources to each user terminal or simply terminal (hereinafter also referred to as a UE (User Equipment)) based on one of the following mechanisms A to C. In this specification, UL scheduling and UL resource allocation may be read interchangeably. A: Dynamic scheduling in which each UE issues a request (SR (Scheduling Request)); that is, the UE dynamically issues requests for radio resources. B: Quasi-static scheduling by the gNB (CS (Configured Scheduling) using CG (Configured Grant)); that is, the gNB issues periodic resource allocations to at least one UE. C: Scheduling based on Buffer Status Reports (BSRs) from the UE; that is, the gNB allocates radio resources based on the BSR, which indicates the amount of data available for UL transmission from the UE.

[0004] The buffer status reporting mechanism operates based on Logical Channel Groups (LCGs). If multiple Logical Channels (LCHs) exist within the same LCG, the buffer status is reported collectively from the UE to the gNB on an LCG basis. An LCG can be mapped to multiple Logical Channels (LCHs). Technical Specification (TS) 38.321 defines the BSR trigger conditions and BSR format.

[0005] The gNB can receive the BSR from the UE and use the information contained in the BSR to perform resource scheduling. For example, the gNB might decide to prioritize the LCG with the most available data while preventing resource depletion in the low-throughput LCG.

[0006] The 3GPP Release 18 (Rel-18) specification stipulates that the User Environment (UE) must notify the gNB of UL delay critical data using the DSR (Delay Status Report). Here, UL delay critical data refers to UL user plane (U-Plane) data for which the remaining time until the PDCP SDU, buffered for each LCG on the UE side, is discarded falls below a threshold set by the gNB. PDCP is an abbreviation for Package Data Convergence Protocol, and SDU is an abbreviation for Service Data Unit. The remaining time is indicated by the PDCP Discover Timer, and the threshold (also called the remaining time threshold) is indicated by the Remaining Time Threhold. The UE notifies the gNB of the remaining time and buffer occupancy (also called buffer capacity, buffer amount, buffer size, etc.) using the DSR (TS38.321 and TS38.300). In this specification, the UL's U-Plane data, UL data, and PDCP SDU may be interchangeable. Also in this specification and in the drawings, UL delay critical data is also referred to as delay data.

[0007] At the RAN2 meeting of Release 19 (Rel-19), enhancements to DSR functionality were discussed with the aim of achieving high-capacity UL scheduling that meets delay requirements. Specifically, it was proposed to expand the parameters of remaining time and buffer capacity for each LCG from a single pair to multiple pairs (dividing the remaining time into multiple ranges) (Patent Document 1). On the other hand, the LCP (Logical Channel Prioritization) specification, which determines when the UE decides to transmit UL data, is implemented for each logical channel (LCH).

[0008] “Discussion on scheduling enhancements”, R2-2407047, 3GPP TSG-RAN WG2 Meeting #127, August 2024

[0009] In the Rel-18 specification, the DSR is an extended message based on the BSR, which reports buffer capacity from the UE to the gNB, and therefore consists of an LCG unit composed of one or more LCHs. Consequently, if there are multiple LCHs within the same LCG where delayed data is accumulating, only the LCH with the minimum remaining time will be notified as the remaining time for the DSR.

[0010] Similarly, in the DSR currently under specification review for Rel-19, if multiple LCHs exist within a certain remaining time range in the LCG, only the minimum remaining time (for a specific LCH) is notified. Therefore, highly accurate UL scheduling based on the remaining time for each LCH cannot be achieved.

[0011] One aspect of this disclosure, in view of the above, aims to provide a mechanism for appropriately performing UL scheduling.

[0012] A communication device according to one aspect of the present disclosure has a transmission means for transmitting a Medium Access Control (MAC) Control Element (CE) to a base station, the CE comprising a field indicating information about the buffer amount of a Data Unit buffered in the communication device, a field indicating information about the remaining time until the Data Unit is discarded, a field indicating information about an LCG (Logical Channel Group), and a field capable of indicating that in one LCG, there are multiple groups of fields, each including the field indicating the buffer amount and the field indicating the remaining time until the Data Unit is discarded.

[0013] According to one aspect of this disclosure, UL scheduling can be performed appropriately.

[0014] This figure shows an example configuration of a wireless communication system according to the first embodiment. This block diagram shows an example hardware configuration of a terminal according to the first embodiment. This block diagram shows an example hardware configuration of a base station according to the first embodiment. This sequence diagram shows an example operation of a terminal and a base station according to the first embodiment. This flowchart shows an example operation of a terminal according to the first embodiment. This figure shows an example of a DSR format according to the first embodiment. This flowchart shows an example operation of a terminal according to the second embodiment. This figure shows an example of a DSR format according to the second embodiment. This flowchart shows an example operation of a terminal according to the third embodiment. This figure shows an example of a DSR format according to the third embodiment. This figure shows an example of a DSR format according to another embodiment.

[0015] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claims. While the embodiments describe multiple features, not all of these features are essential to this disclosure, and the features may be combined in any way. Furthermore, in the attached drawings, the same or similar configurations are given the same reference numerals, and redundant descriptions may be omitted.

[0016] (First Embodiment) <Wireless Communication System> Figure 1 is a diagram showing an example configuration of a wireless communication system according to the first embodiment. The wireless communication system 100 shown in Figure 1 supports XR. Although embodiments will be described below with respect to a 5G system, this disclosure is not intended to be limited to a 5G system. For example, this disclosure may be applied to next-generation mobile communication systems such as 6G, LTE (Long Term Evolution), LTE-A (LTE-Advanced), and combinations thereof. It should be understood that this disclosure is applicable to any wireless communication system that supports XR or similar services.

[0017] The wireless communication system 100 includes user terminals or simply terminals (hereinafter also referred to as UEs) 101 and 151, base stations (hereinafter also referred to as gNBs) 110 and 111, a 5G core network (CN) 102, and an XR application server 103. It goes without saying that the number of UEs, gNBs, CNs, and / or XR application servers present in the wireless communication system 100 is not limited to the numbers shown in Figure 1.

[0018] UE101 and 151 may be augmented reality wearables, such as virtual reality helmets or goggles. A UE may generally be a device capable of wirelessly communicating with one or more CNs (including CN102) via one or more radio access networks (RANs). Such a device may be any wireless device, such as a wireless communication device or terminal, an IoT device, a machine-type communication (MTC) device, a device-to-device (D2D) terminal, or a user device. IoT is an abbreviation for Internet of Things. A user device may be, for example, a smartphone, a desktop computer, a mobile phone, a tablet, a camera, a game console, or a wearable device.

[0019] UE101 and 151 communicate wirelessly with gNB111. UE101 and 151 receive downlink (DL) signals transmitted from gNB111. UE101 and 151 transmit UL signals to gNB111. UL signals include, for example, UL data (signals) and control information (e.g., uplink control information (UCI) including scheduling requests (SR)). UL signals may also include, for example, information regarding the processing capabilities of UE101 and 151 (capability information; e.g., UE capability), reference signals, etc. For example, UE101 may report capability information to gNB111 indicating whether or not it supports LCH-unit DSRs, PDU-set (Protocol Data Unit set)-unit DSRs, DSRs containing a mixture of LCH and LCG units, etc.

[0020] The channels used to transmit UL signals include, for example, a data channel and a control channel. For example, the data channel includes PUSCH (Physical Uplink Shared Channel), and the control channel includes PUCCH (Physical Uplink Control Channel). For example, UE101 and 151 may transmit control information to gNB111 using PUCCH and data signals using PUSCH.

[0021] gNBs 110 and 111 are network nodes that provide access points to the CN, including CN 102, of the UEs, including UEs 101 and 151. gNBs 110 and 111 are part of a RAN composed of gNBs 110 and 111. Hereafter, the terms RAN node, base station, and gNB are used interchangeably. gNBs 110 and 111 are interconnected by Xn interfaces (e.g., as defined in TS38.423) implemented on wired or wireless link 130. gNBs 110 and 111 are connected to CN 102 by NG interfaces (e.g., as defined in TS38.413) implemented on wired or wireless links 140 and 141, respectively.

[0022] Each gNB controls one or more cells. For example, gNB 110 controls cell 120, and gNB 111 controls cell 121. A cell is a geographical area of ​​a radio network defined by the frequency used to transmit data, and can be uniquely identified by a terminal from an identifier (identification information, ID) broadcast across the geographical area. Each gNB can service several UEs. The base station to which a terminal is connected by establishing an RRC connection with the base station is called the terminal's serving base station. A cell controlled by a serving base station and containing terminals is called a serving cell. The interface between the base station and the terminal is the Uu interface. The Uu interface uses SDAP, PDCP, RLC, MAC, PHY, etc., as the protocol sublayer of the user plane (U-plane). SDAP is an abbreviation for Service Data Adaptation Protocol, PDCP is an abbreviation for Package Data Convergence Protocol, RLC is an abbreviation for Radio Link Control, MAC is an abbreviation for Medium Access Control, and PHY is an abbreviation for Physical. Furthermore, the Uu interface uses RRC, PDCP, RLC, MAC, and PHY as protocol sublayers of the control plane (C-Plane).

[0023] gNB111 communicates wirelessly with UE101 and 151. gNB111 receives UL signals transmitted from UE101 and 151. gNB111 transmits DL signals to UE101 and 151. The DL signals include, for example, DL data (signals) and control information. The DL control information includes, for example, downlink control information (DCI) which includes information indicating the scheduling of signal transmission by UE101 and 151 (e.g., UL Grant). For example, the DL signals may also include upper-layer control information (e.g., RRC control information), reference signals, etc.

[0024] The channels used to transmit DL signals include, for example, a data channel and a control channel. For example, the data channel includes a PDSCH (Physical Downlink Shared Channel), and the control channel includes a PDCCH (Physical Downlink Control Channel). For example, gNB111 may transmit control information to UE101 and 151 using the PDCCH and transmit data signals using the PDSCH.

[0025] CN102 includes a user plane function (UPF) 161, which is a network function (NF) that processes user plane communications.

[0026] The XR application server 103 receives requests from clients such as UE101 and 151, executes the XR application in response to the request, and returns the result to the client.

[0027] It is assumed that UE 101 sends and receives XR data for one or more multicast XR sessions directed to XR application server 103. XR data from XR application server 103 is provided to gNB 111 via link 141, CN 102 (e.g., via data network 160 and UPF 161), and transport bearer (or GTP-U tunnel) 106. As described above, gNB 111 controls cell 121 to which UE 101 is connected. XR data from gNB 111 is then transmitted to UE 101 via data radio bearer (DRB) 153. In Figure 1, UE 151 receiving data via DRB 154 is also shown. A radio bearer is a set of PHY (Layer 1) and MAC (Layer 2) parameters that enable higher layer data connectivity between the terminal and the base station. Multiple types of radio bearers are defined in 5G. Multiple types of radio bearers include signaling radio bearers (SRBs) for the control plane, data radio bearers (DRBs), and multicast radio bearers (MRBs). DRBs enable point-to-point communication with a single terminal in the user plane (e.g., unicast).

[0028] MRB enables point-to-point and point-to-point multipoint communication with multiple terminals within the user plane (e.g., multicast / broadcast).

[0029] <Terminal Hardware Configuration> Figure 2 is a block diagram showing an example of the hardware configuration of a terminal according to this embodiment. Below, an example of the hardware configuration of UE101, which is an example of a terminal, will be described, but UE151 can have a similar configuration.

[0030] UE101 has components for sending and receiving communications. For example, UE101 has a central processing unit (CPU) 215, a terminal communication management unit 220, a data storage unit 225, a transceiver 235, an antenna control unit 245, an I / O (Input / Output) controller 255, and an antenna 265. CPU is an abbreviation for Central Processing Unit and is an example of a processor. All of these components can communicate with each other via an internal bus.

[0031] The CPU 215 is configured to execute machine-readable instructions. Once machine-readable instructions are executed by the CPU 215, the UE 101 performs various functions, including controlling the UE 101 as a whole. For example, these functions may involve communication with or interaction with peripheral devices such as a keyboard, screen, mouse, etc. (not shown in Figure 2). The CPU 215 can run operating systems such as iOS®, Windows®, and Android®. The CPU 215 may be a single processor or may include two or more processors that perform the processing necessary for the operation of the UE 101.

[0032] The terminal communication management unit 220 (an example of a (terminal-side) determination means) is configured to control the establishment of communication between the UE 101 and the RAN or base station (e.g., gNB 111), communication with the RAN, and the release of the UE 101 from the RAN. The terminal communication management unit 220 periodically receives notifications from the gNB 111 via the antenna 265, antenna control unit 245, and transceiver 235 regarding available slots for communication between the UE 101 and the gNB 111. Thus, the terminal communication management unit 220 can determine when and how often it should expect to receive incoming data. Furthermore, the terminal communication management unit 220 can identify when and how often it should transmit outgoing data. The terminal communication management unit 220 can determine whether the data belongs to the control plane or the data plane. In one example, the terminal communication management unit 220 can provide a Uu interface. The terminal communication management unit 220 may be implemented by the CPU 215. The terminal communication management unit 220 may be a software-only function implemented by the CPU 215.

[0033] The data storage unit 225 includes random access memory (RAM), read-only memory (ROM), or a combination of both. Additionally or alternatively, the data storage unit 225 may include a mass storage device such as a disk or solid-state drive (SSD). Basic input / output system (BIOS) instructions can be stored in the data storage unit 225. Data transmitted and received with the gNB 111, data processed or performed by the CPU 215, etc., can also be stored in the data storage unit 225.

[0034] The transceiver 235 (an example of a (terminal-side) transmitting means, receiving means, transmitting / receiving means, or communication means) is configured to provide bidirectional wireless communication with other wireless devices (including gNB 111) via the antenna control unit 245 and the antenna 265. For example, the transceiver 235 provides a modem (e.g., a router) and frequency shifter necessary for connecting to one or more wireless networks such as Wi-Fi®, Bluetooth®, LTE, and 5G. The transceiver 235 corresponds to a transmitting unit and a receiving unit (or communication unit).

[0035] Instead of the transceiver 235, the transmitting unit and the receiving unit may exist as separate components. For example, the transceiver 235 may include a PDCP transmitting unit and a receiving unit. The transceiver 235 and / or the PDCP transmitting unit and the receiving unit may be realized by the CPU 215. The transceiver 235 and / or the PDCP transmitting unit and the receiving unit may be a function only of software realized by the CPU 215.

[0036] The transceiver 235 transmits a DSR (an example of a MAC Control Element (CE)) including delay information and buffer information regarding the delay time and the buffer amount respectively associated with the LCH of the UE 101 to the gNB 111.

[0037] The antenna control unit 245 is configured to control the antenna 265 based on an instruction signal from the CPU 215 or the terminal communication management unit 220. For example, the antenna control unit 245 controls the antenna 265 to switch the directivity direction of the antenna 265. The antenna control unit 245 may be realized by the CPU 215. The antenna control unit 245 may be a function only of software realized by the CPU 215.

[0038] The I / O controller 255 provides necessary hardware and manages input / output signals to enable interaction with external peripheral devices. The I / O controller 255 can interact with, for example, all or part of an image capture device, an image rendering device, an audio capture device, an audio rendering device, a sensor device capable of determining the usage position, etc.

[0039] The antenna 265 is composed of one or more antennas. When the antenna 265 is composed of a plurality of antennas, it is configured to provide beamforming capabilities.

[0040] <Hardware Configuration of Base Station> FIG. 3 is a block diagram showing an example of the hardware configuration of the base station according to the present embodiment. Hereinafter, an example of the hardware configuration of the gNB 111, which is an example of the base station, will be described, but the gNB 110 can also have a similar configuration.

[0041] gNB 111 has components for transmitting and receiving communications. For example, gNB 111 has a CPU 315, a base station communication management unit 320, a data storage unit 325, a transceiver 335, an antenna control unit 345, a core network (CN) communication management unit 355, an inter-station communication management unit 365, and an antenna 375. All of these components can communicate with each other via an internal bus.

[0042] The CPU 315 is configured to execute machine-readable instructions. When the machine-readable instructions are executed by the CPU 315, gNB 111 executes various functions, including controlling the entire gNB 111. The CPU 315 may be a single processor, or may include two or more processors that execute the processing necessary for the operation of gNB 111.

[0043] The base station communication management unit 320 is configured to control the establishment of communication with a plurality of UEs including the UE 101 and the UE 151, communication with the UEs, and the release of communication with the UEs. The base station communication management unit 320 includes a scheduler that allocates time and frequency resources for communication with different UEs. Information regarding the scheduling of time and frequency resources is transmitted to the relevant UEs periodically or dynamically. In one example, the base station communication management unit 320 can provide a Uu interface. The base station communication management unit 320 may be implemented by the CPU 315. The base station communication management unit 320 may be a function of only software implemented by the CPU 315.

[0044] The data storage unit 325 includes a RAM, a ROM, or a combination of both. Additionally or alternatively, the data storage unit 325 may include a large-capacity storage device such as a disk or an SSD. BIOS instructions may be stored in the data storage unit 325. Data transmitted and received between the UEs, data processed or to be processed by the CPU 315, etc. may also be stored in the data storage unit 325.

[0045] The transceiver 335 (an example of a base station-side transmitting means, receiving means, transmitting / receiving means, or communication means) is configured to provide bidirectional wireless communication with other wireless devices (including UEs such as UE 101 and other gNBs) via the antenna control unit 345 and the antenna 375. For example, the transceiver 335 provides the modem and frequency shifter necessary to connect to multiple UEs simultaneously using different frequency carriers in time-division duplex (TDD) or frequency-division duplex (FDD). The transceiver 335 corresponds to a transmitting unit and a receiving unit (or a communication unit). Instead of the transceiver 335, the transmitting unit and the receiving unit may exist as separate components. For example, the transceiver 335 may include a PDCP transmitting unit and a receiving unit. The transceiver 335 and / or the PDCP transmitting unit and the receiving unit may be implemented by the CPU 315. The transceiver 335 and / or the PDCP transmitting unit and the receiving unit may be software-only functions implemented by the CPU 315.

[0046] Transceiver 335 receives a DSR from UE101 that includes delay information and buffer information, respectively, relating to the delay time and buffer amount, which are associated with the LCH of UE101.

[0047] The antenna control unit 345 is configured to control the antenna 375 based on instruction signals from the CPU 315 and the base station communication management unit 320. For example, the antenna control unit 345 controls the antenna 375 to switch its directional direction. The antenna control unit 345 may be implemented by the CPU 315. The antenna control unit 345 may also be a software-only function implemented by the CPU 315.

[0048] The CN communication management unit 355 is configured to manage communication between the gNB 111 and the CN (e.g., CN 102). For example, the CN communication management unit 355 may provide a standardized NR interface defined in the 3GPP standard to support such communication. The CN communication management unit 355 may be implemented by the CPU 315. The CN communication management unit 355 may also be a software-only function implemented by the CPU 315.

[0049] The inter-station communication management unit 365 is configured to manage communication between gNB 111 and other gNBs (e.g., gNB 110). For example, the inter-station communication management unit 365 can provide a standardized Xn interface to support such communication. The inter-station communication management unit 365 may be implemented by the CPU 315. The inter-station communication management unit 365 may also be a software-only function implemented by the CPU 315.

[0050] Antenna 375 is composed of one or more antennas. When Antenna 375 is composed of multiple antennas, it is configured to provide beamforming capability.

[0051] <Operation of Terminals and Base Stations> Next, an example of the operation of terminals and base stations according to this embodiment will be described.

[0052] Figure 4 is a sequence diagram showing an example of operation of a terminal and a base station according to this embodiment. More specifically, the operation example shown in Figure 4 relates to UL scheduling. As a prerequisite, UE101 is assumed to have already transmitted UL U-Plane data after sending a scheduling request (SR) to gNB111. UE101 is assumed to have the following three LCHs: LCH#1: Remaining Time (RT) = 10 ms, Buffer Size (BS) = 3 MB. LCH#2: Remaining Time = 8 ms, Buffer Size = 1 MB. LCH#3: LCH#3 with Remaining Time = 5 ms, Buffer Size = 1 MB. The Priority Level (PL) of these three LCHs is the same, 3 (PL = 3). Furthermore, since gNB111 sets a remaining time threshold of 10ms for UE101, delayed data is accumulating in the buffer for all of LCH#1, LCH#2, and LCH#3. In each embodiment, a smaller PL value indicates a higher priority (PL=1 represents the highest priority). Conversely, a larger PL value may indicate a higher priority. Also, the less time remaining for an LCH, the more delayed the UL data in that LCH is. Therefore, information regarding the remaining time for an LCH can also be considered information regarding the delay time associated with that LCH.

[0053] UE101 detects that the remaining time of U-Plane data lingering in each LCH buffer is less than or equal to the remaining time threshold = 10 ms, and determines that this is a trigger for transmitting a DSR to notify gNB111 of the delayed data (S401). In other words, UE101 decides to transmit a DSR to notify gNB111 of the delayed data, triggered by the remaining time being less than or equal to the remaining time threshold = 10 ms. The DSR is transmitted from UE101 to gNB111 using MAC CE (DSR MAC CE), which is a control signal for controlling the MAC layer.

[0054] Here, we will explain the processing when using the conventional method (Rel-18 specification). In the conventional DSR method, remaining time is notified on an LCG basis, so the remaining times of LCH#1, LCH#2, and LCH#3 of the same PL are notified as the same LCG. However, since the DSR is a message format in which the remaining time and buffer capacity are composed of one parameter for each LCG, the minimum remaining time of 5 ms (LCH#3) is set. For this reason, in the conventional method, the remaining time of LCH#1 = 10 ms and the remaining time of LCH#2 = 8 ms are not notified by the DSR even though they are below the remaining time threshold. As a result, for example, if the allocated UL resource from gNB111 is 4 MB, (LCHs of the same priority do not have a specific order specified) UL data in LCH#1, which does not have the minimum remaining time, may be sent first. Therefore, by the time of the next UL transmission, the remaining time on LCH#2 and LCH#3 may become zero, resulting in the discarding of data on these LCHs, which can cause problems such as increased delay and decreased throughput.

[0055] Multimodal XR applications are likely to be associated with multiple QoS flows having different characteristics and QoS (Quality of Service) requirements, and these different characteristics and QoS will be mapped to different DRBs. Therefore, even when only one application is running on a terminal, more LCHs with different priorities will be used. As a result, in the wireless communication system 100 supporting XR, more serious situations (increased latency and reduced throughput) may occur due to the discarding of delayed data.

[0056] Therefore, the following describes the details of this embodiment, which makes it possible to suppress the increase in delay and decrease in throughput due to data discarding.

[0057] Figure 5 is a flowchart illustrating an example of terminal operation. More specifically, Figure 5 shows an example of UE control, where a DSR is sent to the gNB to notify it of the remaining time in LCH units.

[0058] UE101 executes the loop processing shown in Figure 5 (S501) targeting all LCHs (LCH#1 to LCH#3 in the example shown in Figure 4) that are buffering UL data.

[0059] In this embodiment, the loop processing shown in Figure 5 is executed in ascending order of LCH ID or index, but it may also be executed in descending order of LCH ID or index. Furthermore, for example, the processing shown in Figure 5 is executed by the terminal communication management unit 220 of UE101.

[0060] In S502, UE101 checks for each LCH whether there is any UL data whose remaining time is less than or equal to the remaining time threshold. In the example shown in Figure 4, the remaining times for LCH#1, LCH#2, and LCH#3 are all 10ms or less, so UE101 determines that the UL data in these LCHs are delay data (S502; Yes).

[0061] In S503, UE101 sets the LCH-ID, remaining time, and buffer capacity of the corresponding delay data (i.e., LCH) in the DSR.

[0062] Here, an example of the DSR format according to this embodiment will be explained with reference to Figure 6. As shown in Figure 6, this DSR format has fields F601 to F605. Field F601 (LCG ０ ~LCG ７Field F602 (Number of LCHs with delay data) indicates the LCG to which the LCH from which the reported information is detected, i.e., the LCH from which the occurrence of delay data was detected (referred to as the reported LCH), belongs. Field F602 (Number of LCHs with delay data) is a field that indicates the number of LCHs with delay data (reported LCHs) among the LCHs managed by UE101. The information stored in this field is an example of information regarding the number of logical channels. Field F603 (LCH-ID 1) is a field that indicates the ID or index of the reported LCH. Field F604 (Remaining Time 1) is a field that indicates the remaining time of the LCH indicated by field F603. The information stored in field F604 is an example of delay information associated with the LCH. Field F605 (Buffer Size 1) is a field that indicates the buffer capacity of the LCH indicated by field F603. The information stored in field F605 is an example of buffer information associated with the LCH. Field F606 (BT 1) indicates whether the buffer capacity for the LCH indicated by field F603 is selected from the specification list. This DSR has fields corresponding to fields F603 to F606, for each LCH to be reported, as indicated by field F602. Therefore, the DSR includes the remaining time and buffer capacity for the number of LCHs indicated by field F602.

[0063] In the DSR format shown in Figure 6, UE101 sets the ID of LCH#1 to LCH-ID 1 (F603). UE101 also sets Remaining Time 1 (F604) to 10ms, which is the remaining time for LCH#1. Furthermore, UE101 sets Buffer Size 1 (F605) to 3MB, which is the buffer capacity for LCH#1. Similarly, for LCH#2 and LCH#3, UE101 sets the LCH-ID, remaining time, and buffer capacity in the DSR format shown in Figure 6.

[0064] Returning to the explanation of Figure 5, UE101 determines that the U-Plane data remaining in the LCH buffer is non-delayed data if the remaining time is greater than the remaining time threshold (S502; No), and decides not to notify the gNB via DSR (S506). In this case, UE101 will notify information about the non-delayed data, for example, at the BSR transmission cycle.

[0065] After S503 or S506, UE101 checks whether the TDD slot is in UL timing (S504). If the TDD slot is in UL timing (S504; Yes), UE101 confirms the DSR transmission (S507) and sets the number of LCHs to be notified in the DSR in the DSR (S505). In the example shown in Figure 4, UE101 sets the number of LCHs to 3 in Number of LCHs with delay data (F602) in the DSR format shown in Figure 6.

[0066] In summary, if UE101 detects multiple LCHs where delayed data is accumulating before the DSR is transmitted, it sets information for each detected LCH into the DSR.

[0067] Returning to the explanation of Figure 4, UE101 transmits a DSR to gNB111 including the LCH-IDs, remaining time, and buffer capacity of LCH#1, LCH#2, and LCH#3 according to the procedure shown in Figure 5 above (S402). Thus, UE101 transmits the DSR to gNB111 at the timing of the first UL slot of the TDD (S504; Yes) after the DSR transmission trigger (S401) (S402).

[0068] Upon receiving the DSR, gNB111 allocates UL resources (in this case, 2MB) to UE101 (S403). Then, in S404, gNB111 sends a UL Grant to UE101 to notify UE101 of the available UL resources.

[0069] Next, UE101 performs LCP processing to determine the U-Plane data to be transmitted at the next UL timing (S405). In the example shown in Figure 4, UE101 decides to transmit the U-Plane data for ULs located at LCH#2 and LCH#3. Then, UE101 transmits the U-Plane data for ULs via PUSCH (S406).

[0070] At this time, if the UL resources allocated by gNB111 via UL Grant are sufficient to cover the total amount of data accumulating in the buffers of LCH#1, LCH#2, and LCH#3, it is possible to transmit all UL data in a single PUSCH. However, in the example shown in Figure 4, even if the 2 MB of UL data in LCH#2 and LCH#3 can be transmitted preferentially, there are insufficient resources for the 3 MB of UL data in LCH#1. Therefore, the 3 MB of UL data in LCH#1 will have to wait until the next UL transmission. Since 3 MB of UL data is accumulating in the buffer of LCH#1 and the remaining time is 5 ms, UE101 sets information regarding the delayed data for LCH#1 only in the DSR and sends the DSR containing the set information back to gNB111 (S407).

[0071] Upon receiving the DSR transmitted in S407, gNB111 allocates UL resources to UE101 and sends a UL Grant to UE101 (S408). Having received the UL Grant in the same manner as above, UE101 transmits the UL data located on LCH#1 via PUSCH (S409).

[0072] According to the embodiment described above, when delay data exists in multiple LCHs, it becomes possible to notify the remaining time on an LCH-by-LCH basis, and it becomes possible to support UL scheduling that prioritizes LCHs with less remaining time. For example, it becomes possible to perform highly accurate UL scheduling that takes delays on an LCH-by-LCH basis. As a result, throughput reduction and increased delay due to the discarding of UL data can be improved.

[0073] (Second Embodiment) In the first embodiment, a DSR that provides notifications on an LCH basis was described. In this embodiment, UL scheduling based on a DSR that provides notifications on a PDU set basis will be described. This makes it possible to notify which PDU set is experiencing delay when, for example, there are multiple PDU sets (delayed data) in the same LCH that are below a time threshold. Furthermore, this notification makes it possible, for example, when allocating UL resources on the gNB side, to not allocate UL resources to PDU sets of non-delayed data in the LCH, and to allocate UL resources only to PDU sets experiencing delay. Note that the same or similar configurations and operations as in the first embodiment will not be described, and the following will focus on configurations and operations that differ from the first embodiment.

[0074] A PDU set is a collection of PDCP PDUs and forms the smallest unit of an XR frame. A PDU set is a collection of data such that if even one packet fails to send or receive, the other packets also become undecodeable, similar to the image data that makes up one frame of video.

[0075] The second embodiment will be described in detail below with reference to Figures 7 and 8. Note that the processing sequence is the same as that shown in Figure 4, so a detailed explanation will be omitted. The prerequisites are basically the same as those for the first embodiment. The difference from the first embodiment is that LCH#1 includes PDU set #1, PDU set #2, and PDU set #3. For PDU set #1, the remaining time is 3 ms and the buffer capacity is 1 MB; for PDU set #2, the remaining time is 10 ms and the buffer capacity is 1 MB; and for PDU set #3, the remaining time is 20 ms and the buffer capacity is 1 MB.

[0076] Figure 7 is a flowchart illustrating an example of terminal operation. More specifically, Figure 7 shows an example of UE control, where a DSR is sent to the gNB to notify it of the remaining time on a PDU set basis.

[0077] UE101 executes the loop processing shown in Figure 7 (S701) targeting all LCHs (LCH#1 to LCH#3 in the example shown in Figure 4) that are buffering UL data.

[0078] In this embodiment, the loop processing shown in Figure 7 is executed in ascending order of LCH ID or index, but it may also be executed in descending order of LCH ID or index. Furthermore, for example, the processing shown in Figure 7 is executed by the terminal communication management unit 220 of UE101.

[0079] In S702, UE101 checks for each LCH whether there is any UL data whose remaining time is less than or equal to the remaining time threshold. In the examples shown in Figures 4 and 7, the remaining times for LCH#1, LCH#2, and LCH#3 are all 10ms or less, so UE101 determines that the UL data in these LCHs are delay data (S702; Yes).

[0080] Furthermore, in S703, UE101 checks whether there are multiple PDU sets of delayed data within the same LCH. If there are multiple PDU sets of delayed data (S703; Yes), UE101 sets the PDU set ID, remaining time, and buffer capacity of the corresponding PDU set in the DSR for each LCH (LCH-ID) (S704).

[0081] Here, an example of the DSR format according to this embodiment will be explained with reference to Figure 8. As shown in Figure 8, this DSR format has fields F801 to F810. Field F801 (LCG ０ ~LCG ７Field F802 (Number of LCHs with delay data) indicates the LCG to which the LCH (referred to as the Reported LCH) that contains the PDU set for which the reported information is located, i.e., the PDU set for which the occurrence of delayed data was detected, belongs. Field F802 (Number of LCHs with delay data) is a field that indicates the number of LCHs with delayed data (Reported LCHs) among the LCHs managed by UE101. Field F803 (LCH-ID 1) is a field that indicates the ID or index of the LCH to be reported. Field F804 (Number of PDU sets in LCH-ID 1) indicates the number of PDU sets for which the occurrence of delayed data was detected in the LCH indicated by field F803. The information stored in this field is an example of information regarding the number of PDU sets. Field F805 (PDU set ID 1) is a field that indicates the ID or index of the PDU set for which the occurrence of delayed data was detected in the LCH indicated by field F803. Field F806 (Remaining Time 1) is a field that indicates the remaining time of the PDU set indicated by field F805 (field F809 is similar). The information stored in field F806 is an example of delay information associated with a PDU set, and can also be said to be delay information associated with the LCH (where the PDU set resides). Field F807 (Buffer Size 1) is a field that indicates the buffer capacity of the PDU set indicated by field F805 (field F810 is similar). The information stored in field F807 is an example of buffer information associated with a PDU set, and can also be said to be buffer information associated with the LCH (where the PDU set resides). In this DSR, for each LCH, there are fields corresponding to fields F805 to F807, for each LCH in which delay data has been detected. In addition, this DSR also has fields corresponding to the above fields for other reported LCHs.

[0082] In the DSR format shown in Figure 8, UE101 sets LCH-ID 1 (F803) to LCH#1. UE101 also sets PDUset-ID 1 (F805) to the ID of PDUset #1. Furthermore, UE101 sets Remaining Time 1 (F806) to 3ms, which is the remaining time for PDUset #1. UE101 also sets Buffer Size 1 (F807) to 1MB, which is the buffer capacity for PDUset #1. Similarly to PDUset #1, UE101 sets PDUset-ID 2 (F808) to the ID of PDUset #2. Furthermore, UE101 sets Remaining Time 2 (F809) to 10ms, which is the remaining time for PDUset #2. Furthermore, UE101 sets Buffer Size 2 (F810) to 1MB, which is the buffer capacity of PDU set #2. Since the remaining time for PDU set #3 is greater than the remaining time threshold, its remaining time and other information are not notified by DSR. The remaining time and other information for PDU set #3 will be notified by BSR, for example, during the BSR transmission cycle (S708). For LCH #2 and LCH #3, where there are no multiple PDU sets, UE101 sets the LCH-ID, remaining time, and buffer capacity in the same manner as in the first embodiment (S707).

[0083] After S704, S707, or S708, UE101 checks whether the TDD slot is UL timing (S705). If the TDD slot is UL timing (S705; Yes), UE101 confirms the DSR transmission (S709) and sets the number of LCHs and PDU sets to be notified in the DSR in the DSR (S706). In the examples shown in Figures 4 and 7, UE101 sets the number of LCHs to 3 in Number of LCHs with delay data (F802) in the DSR format shown in Figure 8. Also, in the DSR format shown in Figure 8, UE101 sets the number of PDU sets corresponding to the delay data in LCH #1 to 2 in Number of PDU sets in LCH-ID 1 (F804).

[0084] UE101 transmits a DSR including the LCH-ID, PDUset-ID, remaining time, and buffer capacity for LCH#1, LCH#2, and LCH#3 to gNB111 according to the procedure shown in Figure 7 above (step corresponding to S402 in Figure 4).

[0085] According to the embodiment described above, when multiple PDU sets within an LCH contain delayed data, it becomes possible to notify the remaining time on a PDU set-by-PDU set basis. Therefore, it becomes possible to support UL scheduling that prioritizes LCHs containing PDU sets with less remaining time. For example, it becomes possible to perform highly accurate UL scheduling that takes delays on an LCH-by-PCH basis. As a result, throughput reduction and increased delay due to discarding UL data can be improved.

[0086] (Third Embodiment) In the first embodiment, a DSR that notifies on an LCH basis was described, and in the second embodiment, a DSR that notifies on a PDU set basis was described. In this embodiment, the transmission of a DSR in which LCH and LCG are mixed will be described.

[0087] The DSR according to this embodiment has advantages over the Rel-18 specification DSR in the following cases, for example: (1) When LCGs with 1 LCH setting and LCGs with multiple LCH setting (LCH notification) are mixed. (2) When notification of delayed data below the remaining time threshold is to be sent using an LCH-based DSR, and advance notification of UL data that is not delayed data but will become delayed data at the next UL transmission timing (4ms later) is to be sent using an LCG-based DSR, and notified together.

[0088] The following explanation of the UE's operation will primarily be based on case (2). In addition to notifying delayed data on an LCH basis, the delay in UL scheduling can be improved at an earlier stage by providing advance notification of data that is not delayed data but could become delayed data in the next UL transmission.

[0089] Note that the same or similar configurations and operations as those in the first or second embodiment will not be described, and the following description will focus on configurations and operations that differ from those in the first or second embodiment.

[0090] The third embodiment will be described in detail below with reference to Figures 9 and 10. Since there are overlaps between the LCH unit DSR and the first embodiment, the explanation of those parts will be omitted. For example, S901 to S904, S907, S908 and S910 in Figure 9 are the same as S501 to S504, S505, S506 and S507 in Figure 5, respectively, and therefore their explanation will be omitted.

[0091] Figure 9 is a flowchart illustrating an example of terminal operation. More specifically, Figure 9 shows an example of controlling a UE that transmits a combined DSR (Distributed Signal Relay) consisting of DSRs for each LCH (Low Channel) and DSRs for each LCG (Low Channel).

[0092] By S904, UE101 determines the DSR settings for each LCH, and then checks if there is any UL data with a remaining time below the report threshold (S905). Here, the report threshold is a value greater than the remaining time threshold and is a threshold for pre-notifying data that may become delayed data at the next UL transmission timing. Since the comparison with the remaining time threshold has already been made by S904, for example, if the remaining time threshold = 10 ms and the report threshold = 20 ms, the remaining time for reporting set in S906 will be greater than 10 ms and less than or equal to 20 ms. The comparison in S905 makes it possible to pre-notify data that is not delayed data but may become delayed data at the next UL transmission timing (referred to as potentially delayed data). Thus, the trigger for UE101 to detect potentially delayed data is when the remaining time of the LCH falls below the report threshold. And with this notification, if UL resources are available after the decision to send delayed data, potentially delayed data can be sent first, thereby preventing delayed data from occurring. In the case of prior notification, strict notification at the LCH level is not required; therefore, remaining time and other information are notified at the LCG level, which can be composed of multiple LCHs. The report threshold is set or notified to UE101 by gNB111 via RRC signaling (parameters), MAC CE, and / or DCI. These RRC signaling (parameters), MAC CE, and / or DCI are examples of information regarding the report threshold, and UE101 receives information regarding the report threshold from gNB111.

[0093] Here, an example of the DSR format according to this embodiment will be explained with reference to Figure 10. As shown in Figure 10, this DSR format has fields F1001 to F1009. Field F1001 (LCG ０ ~LCG ７ ) indicates the LCG to which the LCH for which there is reported information, i.e., the LCH for which the occurrence of delay data was detected (referred to as the reported LCH), belongs, or the LCG for which there is reported information. Field F1002 (Number of delay LCHs in LCG) ０ ) is LCG ０It is a field indicating the number of LCHs belonging to that have delay data. Here, LCG ０ is described, but if LCG ０ is not the reporting target, the number of report target LCHs belonging to another LCG is stored. The information stored in this field is an example of information regarding the number of logical channels. Field F1003 (DF 1) is a field indicating a flag indicating whether the target data is delay data or delay-possible data. When information is reported in LCH units, the value of this field is, for example, "1". Field F1004 (LCH-ID 1) is a field indicating the ID or index of the reported LCH belonging to LCG ０ . Field F1005 (Remaining Time 1) is a field indicating the remaining time of the LCH indicated by Field F1004. The information stored in Field F1005 is an example of delay information associated with the LCH. Field F1006 (Buffer Size 1) is a field indicating the buffer capacity of the LCH indicated by Field F1004. The information stored in Field F1006 is an example of buffer information associated with the LCH. In this DSR, there are fields corresponding to Fields F1005 to F1006 for the number of LCHs belonging to LCG ０ that have delay data. Also, for other LCGs, there are fields indicating the same information as above. Also, in addition to such information in LCH units, there are also fields F1007 to F1009 indicating information in LCG units. Field F1007 (DF 7) is a field indicating a flag indicating whether the target data is delay data or delay-possible data. When information is reported in LCG units, the value of this field is, for example, "0". Field F1008 (Remaining Time 7) is a field indicating the remaining time of the LCG (for example, the minimum remaining time among the LCHs belonging to the LCG).

[0094] The information stored in field F1008 is an example of delay information associated with the LCG. The less time remaining in the LCG, the more delayed the UL data in the LCG is. Therefore, the information regarding the remaining time in the LCG can also be considered information regarding the delay time associated with the LCG. Field F1009 (Buffer Size 7) is a field that indicates the total buffer capacity of the LCG. The information stored in field F1009 is an example of buffer information associated with the LCG. For other LCGs where information is reported on an LCG basis, there are fields that show similar information as described above.

[0095] If UE101 has UL data with a remaining time below the report threshold (S905; Yes), it sets the following (S906). In the DSR format shown in Figure 10, UE101 sets the remaining time in Remaining Time 7 (F1008) (S906). UE101 also sets the total LCG data amount in Buffer Size 7 (F1009) (S906). Furthermore, UE101 sets the aforementioned flags (DF; F1003, F1007) as new parameters according to the third embodiment, indicating whether the target data is delayed data or potentially delayed data (S906).

[0096] If there is no UL data below the report threshold, UE101 does not set anything in DF (S909). In this way, DF indicates whether the corresponding delay information and buffer information relate to the delay time and buffer amount associated with the LCH of UE101, or to the delay time and buffer amount associated with the LCG of UE101, respectively.

[0097] According to the embodiment described above, as with other embodiments, the decrease in throughput and increase in delay due to the discarding of UL data can be improved. Furthermore, according to this embodiment, it becomes possible to flexibly notify LCG-unit DSR and LCH-unit DSR, thereby preventing delayed data from occurring.

[0098] In all of the above embodiments, the UE 101 (for example, the terminal communication management unit 220) discards any UL data remaining in the LCH when the remaining time of the LCH expires (becomes zero). Furthermore, when UL data is discarded, the UE 101 transmits information to the gNB 111 indicating that the UL data has been discarded. The UE 101 operates similarly when the remaining time of the LCG expires (becomes zero).

[0099] (Other Embodiments) In the above embodiments, various examples of DSR formats have been described, but other DSR formats may be used. For example, the DSR format shown in Figure 11 may be used. The DSR format shown in Figure 11 has fields F1101 to F1104. Fields F1101 to F1104 are the same as fields F602 to F605 in Figure 6. The difference between the DSR format shown in Figure 11 and the DSR format shown in Figure 6 is that the LCG attribute flag (field F601) that exists in Figure 6 does not exist in Figure 11. The UE may notify the DSR using the format shown in Figure 11.

[0100] In the above embodiment, a DSR conforming to the Rel-18 specification may be used. For example, UE101 can transmit a DSR on an LCG basis by using a DSR format conforming to the Rel-18 specification. Alternatively, for example, one of the DSRs described in the above embodiment may be used in combination with a DSR conforming to the Rel-18 specification. In this case, UE101 may notify gNB111 in advance of which LCH to which the DSR described in the above embodiment is applied and which LCH (i.e., LCG) to which the DSR conforming to the Rel-18 specification is applied. Alternatively, the DSR described in the first embodiment may be used in combination with the DSR described in the second embodiment.

[0101] This disclosure can also be implemented by supplying a program that implements one or more of the functions of each of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. Furthermore, this disclosure can also be implemented by a circuit (e.g., ASIC or FPGA) that implements one or more functions. ASIC is an abbreviation for Application Specific Integrated Circuit, and FPGA is an abbreviation for Field Programmable Gate Array.

[0102] Any two or more of the components of UE101 and gNB111 described above may be integrated, or one component may be divided into two or more (sub)components.

[0103] The names of the components and parameters of UE101 and gNB111 described above are merely examples and may be changed to other names.

[0104] The order of the processing procedures, sequences, flowcharts, etc., in the embodiments described above may be rearranged as long as they do not contradict each other. For example, the methods described above present various step elements using an exemplary order and are not limited to the specific order presented.

[0105] Furthermore, the classification of items in the above description is not essential to this disclosure, and matters described in two or more items may be used in combination as necessary, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other).

[0106] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0107] This application claims priority based on Japanese Patent Application No. 2025-007711, filed on January 20, 2025, and all of its contents are incorporated herein by reference.

Claims

1. A communication device that operates as a terminal capable of communication compliant with the 3GPP (The 3rd Generation Partnership Project) standard, the communication device having a transmission means for transmitting a Medium Access Control (MAC) Control Element (CE) to a base station, the CE comprising: a field indicating information regarding the buffer amount of a Data Unit buffered in the communication device; a field indicating information regarding the remaining time until the Data Unit is discarded; a field indicating information regarding an LCG (Logical Channel Group); and a field capable of indicating that in one LCG, there are multiple groups of fields, each including the field indicating the buffer amount and the field indicating the remaining time until the Data Unit is discarded.

2. The communication device according to claim 1, characterized in that, in a single LCG, a field capable of indicating the existence of multiple field groups, each consisting of a field indicating information about the remaining time until the Data Unit is discarded and a field indicating information about the buffer amount, stores one or more values.

3. A communication device that operates as a communication-capable terminal compliant with the 3GPP (The 3rd Generation Partnership Project) standard, having a transmission means for transmitting a MAC (Medium Access Control) CE (Control Element) to a base station, the MAC including a field indicating information about the buffer amount of a Data Unit buffered in the communication device, a field indicating information about the remaining time until the Data Unit is discarded, a field indicating information about an LCG (Logical channel group), and a predetermined field, wherein when a first value is stored in the predetermined field, one LCG includes one field group including the field indicating information about the remaining time until the Data Unit is discarded and the field indicating information about the buffer amount, and when a second value is stored in the predetermined field, one LCG includes the Data A communication device characterized by including a plurality of fields, each including a field indicating information about the remaining time until a unit is discarded and a field indicating information about the buffer amount.

4. The communication device according to claim 3, characterized in that the second value is the first value plus one or more values.

5. The communication device according to any one of claims 1 to 4, characterized in that the field indicating information about the LCG (Logical channel group) consists of eight consecutive bits.

6. The communication device according to any one of claims 1 to 5, further comprising a determination means for determining to transmit the MAC CE when the remaining time until the buffered Data Unit is discarded falls below a threshold.

7. The communication device according to claim 6, wherein the transmitting means transmits the MAC CE at the timing of the first up slot of the time-division duplex after the trigger.

8. When multiple Data Units are detected in which the remaining time until the buffered Data Unit is discarded is less than or equal to a threshold, the MAC CE has a single LCG in which there are multiple groups of fields, each including a field indicating information about the remaining time until the Data Unit is discarded and a field indicating information about the buffer amount.

9. The communication device according to claim 1, characterized in that the field indicating the buffer amount of the Data Unit buffered in the communication device consists of eight consecutive bits.

10. The communication device according to claim 1, characterized in that the Data Unit buffered in the communication device is a PDCP (Packet Data Convergence Protocol) SDU (Service Data Unit).

11. The communication device according to claim 1, further comprising a disposal means for disposing of a Data Unit when the remaining time until the Data Unit buffered in the communication device is disposed of becomes zero.

12. The communication device according to claim 11, wherein the transmitting means transmits information to the base station indicating that the uplink data has been discarded when the uplink data has been discarded by the discarding means.

13. A communication device having a receiving means for receiving a Medium Access Control (MAC) Control Element (CE) from a communication device operating as a terminal, the CE comprising: a field indicating information regarding the buffer amount of a Data Unit buffered in a communication device operating as a terminal; a field indicating information regarding the time until the Data Unit is discarded; a field indicating information regarding an LCG (Logical channel group); and a field capable of indicating that in one LCG, there are multiple groups of fields including a field indicating information regarding the time until the Data Unit is discarded and a field indicating information regarding the buffer amount.

14. A base station capable of communication in accordance with the 3GPP (The 3rd Generation Partnership Project) standard, having a receiving means for receiving a MAC (Medium Access Control) CE (Control Element) from a communication device operating as a terminal, the MAC including a field indicating information regarding the buffer amount of a Data Unit buffered in a communication device operating as a terminal, and a predetermined field, wherein when a first value is stored in the predetermined field, one LCG includes one group of fields including a field indicating information regarding the remaining time until the Data Unit is discarded and a field indicating information regarding the buffer amount, and when a second value is stored in the predetermined field, one LCG includes multiple groups of fields including a field indicating information regarding the remaining time until the Data Unit is discarded and a field indicating information regarding the buffer amount.

15. A control method performed by a communication device operating as a terminal capable of communication compliant with the 3GPP (The 3rd Generation Partnership Project) standard, comprising a transmission step of transmitting a MAC (Medium Access Control) CE (Control Element) to a base station, the MAC including a field indicating information regarding the buffer amount of a Data Unit buffered in the communication device, a field indicating information regarding the remaining time until the Data Unit is discarded, a field indicating information regarding an LCG (Logical channel group), and a predetermined field, wherein when a first value is stored in the predetermined field, one LCG includes one group of fields including the field indicating information regarding the remaining time until the Data Unit is discarded and the field indicating information regarding the buffer amount, and when a second value is stored in the predetermined field, A control method in which a single LCG includes a group of fields, each including a field that indicates information about the remaining time until the Data Unit is discarded, and a field that indicates information about the buffer amount.

16. A control method performed by a base station capable of communication compliant with the 3GPP (The 3rd Generation Partnership Project) standard, comprising a receiving step of receiving a MAC (Medium Access Control) CE (Control Element) which includes a field indicating information about the buffer amount of a Data Unit buffered in a communication device acting as a terminal, a field indicating information about the remaining time until the Data Unit is discarded, a field indicating information about an LCG (Logical channel group), and a predetermined field, wherein when a first value is stored in the predetermined field, one LCG includes one field group including the field indicating information about the remaining time until the Data Unit is discarded and the field indicating information about the buffer amount, and when a second value is stored in the predetermined field, one LCG includes the Data A control method comprising a group of fields, each including a field indicating information about the remaining time until the Unit is discarded, and a field indicating information about the buffer amount.

17. A program for causing a computer to perform the control method described in claim 15 or 16.

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