Wireless terminal and method

Abstract

A wireless terminal (1B) negotiates, with a peer terminal (1A), DRX settings for the wireless terminal (1B) to receive unicast communications via a direct interface between the wireless terminal (1B) and the peer terminal (1A). The wireless terminal (1B) indicates to the peer terminal (1A) whether or not the wireless terminal (1B) will perform discontinuous reception (DRX) operations on the basis of enabled DRX settings for receiving unicast communications from the peer terminal (1A), indicating same for the period that the DRX settings are negotiated and remain enabled. This can contribute, for example, to prevent an increase in the wireless terminal signaling load for DRX for device-to-device (D2D) communications.

Description

Technical Field

[0001] The present disclosure relates to direct communication between wireless terminals (device-to-device (D2D) communication), and particularly to discontinuous reception (DRX) performed by a wireless terminal that receives D2D communication.

Background Art

[0002] A form in which a wireless terminal directly communicates with another wireless terminal without going through an infrastructure network such as a base station is generally called device-to-device (D2D) communication. D2D communication can be integrated with or supported by a cellular network. Proximity-based services (ProSe) defined in Third Generation Partnership Project (3GPP (registered trademark)) Release 12 and later provide a system architecture for D2D communication supported by a cellular network. In addition, the cellular Vehicle-to-Everything (V2X) service defined since 3GPP Release 14 refers to ProSe and uses D2D communication between wireless terminals. D2D communication supported by a cellular network can also be used for other applications and services (e.g., public safety applications) other than V2X services.

[0003] The interface between 3GPP radio terminals (i.e., User Equipment (UEs)) used for the control plane and user plane for D2D communication is called the PC5 interface (or reference point). The PC5 interface can be based on Evolved Universal Terrestrial Radio Access (E-UTRA) sidelink capability, and further, on 5G New Radio (NR) sidelink capability. D2D communication over the PC5 interface is called sidelink communication. D2D communication (or sidelink communication) over the E-UTRA-PC5 (or Long Term Evolution (LTE) based PC5) interface is connectionless, meaning it is in broadcast mode at the Access Stratum (AS) layer. In contrast, user plane communication over the NR PC5 interface supports unicast mode, groupcast mode, and broadcast mode at the AS layer.

[0004] To support various V2X and public safety use cases, the 3GPP RAN Working Group is currently considering the development of a standard specification for Release 17 NR sidelink enhancement. One of the objectives of this study item is to support discontinuous reception (DRX) in sidelinks (see, for example, Non-Patent Documents 1-6). Current agreements include: NR sidelink unicast supports signaling exchange, including both Rx-UE to Tx-UE and Tx-UE to Rx-UE, for DRX configurations in each direction where one UE is the Tx-UE and the other is the Rx-UE. Tx-UE centric DRX configuration determination based on assistance information from the Rx-UE is the baseline for NR sidelink unicast.

[0005] In Tx-UE centric DRX configuration determination, the Rx-UE sends assistance information to the Tx-UE, and the Tx-UE makes the final decision on the DRX configuration while considering the assistance information. The assistance information sent by the Rx-UE may include, for example, information about power saving, such as preferences and constraints, or one or both. The assistance information may also include current DRX configurations for one or more other SL connections. More specifically, the assistance information may include a set of DRX configurations for all links where the Rx-UE has already configured DRX, so that the Tx-UE can make the decision on behalf of the Rx-UE.

[0006] In contrast, Rx-UE centric DRX configuration determination involves the Tx-UE sending assistance information to the Rx-UE, which then makes the final decision on the DRX configuration while considering the assistance information. The assistance information sent by the Tx-UE may include the Tx-UE's traffic patterns, or it may include one or more DRX configuration candidates that enable the Tx-UE to meet its latency requirements for a given traffic pattern. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] InterDigital Inc., Apple, Huawei, "On TX Centric vs RX Centric Approaches for DRX Configuration Determination", R2-2104867, 3GPP TSG-RAN WG2 Meeting #114-e, May 19-27, 2021 [Non-Patent Document 2] ZTE Corporation, Sanechips, "Discussion on SL DRX configuration", R2-2105077, 3GPP TSG-RAN WG2 Meeting #114-e, May 19-27, 2021 [Non-Patent Document 3] Huawei, HiSilicon, "Consideration on the sidelink DRX for unicast", R2-2105083, 3GPP TSG-RAN WG2 Meeting #114-e, May 19-27, 2021 [Non-Patent Document 4] Apple, "Discussion on remaining issues of SL DRX", R2-2105132, 3GPP TSG-RAN WG2 Meeting #114-e, May 19-27, 2021 [Non-Patent Document 5] ZTE, "[AT113bis-e]

[0708] [V2X / SL] DRX configuration for SL groupcast and broadcast", R2-2105912, 3GPP TSG-RAN WG2 Meeting #114-e, May 19-27, 2021 [Non-Patent Document 6] SHARP, "Discussion on co-existence with UEs not supporting SL DRX", R2-2105277, 3GPP TSG-RAN WG2 Meeting #114-e, May 19-27, 2021 [Overview of the project] [Problems that the invention aims to solve]

[0008] The inventors investigated DRX in D2D communication (e.g., NR sidelink unicast) and identified various issues. One of these issues concerns the temporary suspension and (re)start of DRX operation based on valid DRX settings.

[0009] Specifically, a UE (Rx-UE) may receive multiple sidelink communications (transmits) from multiple UEs (Tx-UEs). These multiple sidelink communications may include multiple unicast communications, groupcast communications, broadcast communications, or any combination thereof. The UE (Rx-UE) may have multiple DRX settings configured (or negotiated with each transmitting UE) for each of these multiple sidelink transmits by each transmitting UE (Tx-UEs). And, considering multiple DRX settings, there may be situations where the UE (Rx-UE) is (effectively) unable to perform DRX operation or does not require DRX operation. However, such situations are expected to occur only temporarily. Therefore, the UE (Rx-UE) may be able to resume DRX operation once some sidelink communications have finished. In this case, if the UE (Rx-UE) has to reconfigure, re-determine, and re-negotiate DRX settings for one or more sidelink unicasts, this may lead to an increase in the signaling load on the UE (Rx-UE). On the other hand, if it is possible to inform the corresponding Tx-UEs that a DRX setting for one or more sidelink unicasts has been negotiated and is enabled, but the UE (Rx-UE) is not (effectively) performing DRX operation, this could potentially increase the opportunities for the Tx-UEs to transmit.

[0010] Alternatively, it may be preferable for the Tx-UE to be able to temporarily send additional data or signaling to the Rx-UE while the DRX configuration for sidelink unicast is negotiated and active. In this case, if the Tx-UE and Rx-UE have to reconfigure, re-determine, or re-negotiate their current DRX configurations, this may lead to an increased signaling load on the Tx-UE and Rx-UE.

[0011] One of the objectives that the embodiments disclosed herein seek to achieve is to provide apparatus, methods, and programs that contribute to solving at least one of several problems, including those described above. It should be noted that this objective is only one of several objectives that the embodiments disclosed herein seek to achieve. Other objectives or problems and novel features will be revealed in this specification or in the accompanying drawings. [Means for solving the problem]

[0012] In a first embodiment, the wireless terminal includes at least one wireless transceiver and at least one processor coupled to the at least one wireless transceiver. The at least one processor is configured to negotiate with the peer terminal a discontinuous reception (DRX) setting for the wireless terminal's reception of unicast communications over a direct interface between the wireless terminal and the peer terminal. The at least one processor is configured to indicate to the peer terminal whether the wireless terminal will perform DRX operations based on the valid DRX setting to receive the unicast communications while the DRX setting is negotiated and valid.

[0013] In a second embodiment, the wireless terminal includes at least one wireless transceiver and at least one processor coupled to the at least one wireless transceiver. The at least one processor is configured to negotiate with the peer terminal a discontinuous reception (DRX) setting for the peer terminal's reception of unicast communications over a direct interface between the wireless terminal and the peer terminal. The at least one processor is configured to receive first information from the peer terminal indicating whether the peer terminal will perform DRX operations based on the valid DRX setting to receive the unicast communications while the DRX setting is negotiated and valid.

[0014] In a third embodiment, the method performed by the wireless terminal includes (a) negotiating with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communications by the wireless terminal on a direct interface between the wireless terminal and the peer terminal, and (b) indicating to the peer terminal whether or not the wireless terminal will perform a DRX operation based on the valid DRX setting to receive the unicast communications while the DRX setting has been negotiated and is valid.

[0015] In a fourth aspect, a method performed by a wireless terminal includes (a) negotiating with the peer terminal a discontinuous reception (DRX) setting for the peer terminal to receive unicast communications on a direct interface between the wireless terminal and the peer terminal; and (b) receiving first information from the peer terminal indicating whether the peer terminal will perform a DRX operation based on the valid DRX setting to receive the unicast communications while the DRX setting is negotiated and valid.

[0016] In a fifth embodiment, the wireless terminal includes at least one wireless transceiver and at least one processor coupled to the at least one wireless transceiver. The at least one processor is configured to negotiate with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communications by the wireless terminal over a direct interface between the wireless terminal and the peer terminal. The at least one processor is configured to receive first information from the peer terminal indicating whether the wireless terminal is permitted to perform DRX operations based on the valid DRX setting to receive the unicast communications while the DRX setting is negotiated and valid.

[0017] In a sixth embodiment, the wireless terminal includes at least one wireless transceiver and at least one processor coupled to the at least one wireless transceiver. The at least one processor is configured to negotiate with the peer terminal a discontinuous reception (DRX) setting for the peer terminal's reception of unicast communications over a direct interface between the wireless terminal and the peer terminal. The at least one processor is configured to indicate to the peer terminal whether it is permitted to perform DRX operations based on the valid DRX setting to receive the unicast communications while the DRX setting is negotiated and valid.

[0018] In a seventh aspect, a method performed by a wireless terminal includes (a) negotiating with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communications by the wireless terminal on a direct interface between the wireless terminal and the peer terminal, and (b) receiving first information from the peer terminal indicating whether the wireless terminal is permitted to perform DRX operations based on the valid DRX setting to receive the unicast communications while the DRX setting is negotiated and valid.

[0019] In an eighth aspect, the method performed by the wireless terminal includes: (a) negotiating with the peer terminal a discontinuous reception (DRX) setting for reception by the peer terminal of unicast communication on a direct interface between the wireless terminal and the peer terminal; and (b) indicating to the peer terminal whether the peer terminal is permitted to perform a DRX operation based on the effective DRX setting to receive the unicast communication while the DRX setting is negotiated and effective.

[0020] A ninth aspect is directed to a program. When the program is loaded into a computer, it includes a set of instructions (software code) for causing the computer to perform the method according to the above-described third, fourth, seventh, or eighth aspect. [Advantages of the Invention]

[0021] According to the above aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems related to DRX for D2D communication. [Brief Description of the Drawings]

[0022] [Figure 1] It is a diagram showing a configuration example of a wireless communication system according to an embodiment. [Figure 2] It is a diagram showing an AS protocol stack of a control plane for RRC at a PC5 interface. [Figure 3] It is a diagram showing an AS protocol stack of a control plane for PC5-S at a PC5 interface.​​​​​​​​​​​This figure shows an example of signaling between UEs according to the embodiment. [Figure 8] This figure shows an example of signaling between UEs according to the embodiment. [Figure 9] This figure shows an example of signaling between UEs according to the embodiment. [Figure 10] This figure shows an example of signaling between UEs according to the embodiment. [Figure 11] This figure shows an example of signaling between UEs according to the embodiment. [Figure 12] This is a block diagram showing an example configuration of a UE according to the embodiment. [Modes for carrying out the invention]

[0023] The following describes specific embodiments in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numeral, and redundant explanations are omitted where necessary for clarity.

[0024] The multiple embodiments described below can be implemented independently or in combination as appropriate. These multiple embodiments have novel features that differ from each other. Therefore, these multiple embodiments contribute to solving different objectives or problems and contribute to producing different effects.

[0025] The following embodiments are described primarily with reference to 3GPP fifth-generation mobile communication systems (5G systems). However, these embodiments may also be applied to other wireless communication systems that support 3GPP NR sidelink communication and similar D2D communication technologies.

[0026] As used herein, depending on the context, “(if)” may be interpreted as meaning “when,” “at or around the time,” “after,” “upon,” “in response to determining,” “in accordance with a determination,” or “in response to detecting.” These expressions may be interpreted as having the same meaning depending on the context.

[0027] <First Embodiment> Figure 1 shows an example configuration of a wireless communication system according to several embodiments, including this embodiment. A Radio Access Network (RAN) (node ​​eg, gNB) 2 manages cell 21 and can perform cellular communication (101 and 102) with multiple wireless terminals (UEs) 1, including UE1A and UE1B, using cellular communication technology (i.e., NR Radio Access Technology). In the example in Figure 1, for the sake of simplicity, UE1A and UE1B are shown to be located within the same cell 21, but this arrangement is only one example. For example, UE1A may be located in one of two adjacent cells managed by different RAN nodes 2, and UE1B may be located in the other cell. Alternatively, at least one of UE1A and UE1B may be located outside the coverage of one or more RAN nodes 2 (i.e., partial coverage, out-of-coverage).

[0028] Each of UE1A and UE1B has at least one wireless transceiver and is configured to perform cellular communication (101 or 102) with RAN node 2 and D2D communication (i.e., sidelink communication) over the inter-UE direct interface (i.e., NR PC5 interface or NR sidelink) 103. This sidelink communication includes unicast mode communication (sidelink unicast) and may further include one or both of groupcast mode communication and broadcast mode communication.

[0029] Figures 2, 3, and 4 show the AS protocol stacks of the PC5 interface 103. As shown in Figure 2, the AS protocol stack of the control plane for the Sidelink Control Channel (SCCH) for RRC includes RRC, Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), and MAC sublayers, as well as the Physical (PHY) layer. The SCCH is a sidelink logical channel for transmitting control information (i.e., PC5-RRC and PC5-S messages) from one UE to another UE(s).

[0030] The PC5 interface 103 supports the PC5 Signalling (PC5-S) protocol. As shown in Figure 3, in the control plane AS protocol stack for SCCH for PC5-S, PC5-S sits above the PDCP, RLC, and MAC sublayers as well as the physical layer. PC5-S is used for control plane signaling on the PC5 interface 103 for secure unicast Layer-2 links (or PC5 unicast links). Specifically, PC5-S provides signaling for establishing, correcting, and releasing PC5 unicast links. The PC5 unicast link between UE1A and UE1B is associated with the Application Layer ID and Layer-2 ID of UE1A, and the Application Layer ID and Layer-2 ID of UE1B. The PC5 unicast link is bidirectional. Therefore, UE1A can send application data (e.g., V2X service data, public safety service data) to UE1B over the PC5 unicast link, and UE1B can also send application data to UE1A over the same PC5 unicast link.

[0031] There is a one-to-one correspondence between a PC5 unicast link and a PC5-RRC connection. A PC5-RRC connection is a logical connection between two UEs1 for a SourceLayer-2 ID and Destination Layer-2 ID pair. A PC5-RRC connection is considered to have been established after the corresponding PC5 unicast link has been established. In other words, a PC5-RRC connection is established in response to the establishment of the corresponding PC5 unicast link. Specifically, if a UE1 (RRC layer) is requested by a layer of sidelink signaling radio bearer (SRB) to send a PC5-S message to a particular destination, it establishes a logical channel (SCCH) for the PDCP entity, the RLC entity, and the sidelink SRB for the PC5-S message based on a predefined SCCH configuration, and considers that a PC5-RRC connection has been established for that destination. Alternatively, if the upper layer indicates that a PC5-RRC connection has been established for a specific destination, UE1 (RRC layer) establishes a logical channel (SCCH) for PDCP entities, RLC entities, and sidelink SRBs for PC5-RRC messages for that destination based on a predefined Sidelink Control Channel (SCCH) setting, and considers that the PC5-RRC connection has been established.

[0032] Figure 4 shows the AS user plane protocol stack for Sidelink Traffic Channel (STCH). STCH is a sidelink logical channel for transmitting user data (e.g., V2X service data) from one UE to another UE(s). The protocol stack includes Service Data Adaptation Protocol (SDAP), PDCP, RLC, and MAC sublayers, as well as a PHY layer.

[0033] The following section, with reference to Figure 5, describes a specific example of DRX signaling by UE1B for receiving unicast communications (transmits) sent from UE1A. For convenience of explanation, UE1A will be referred to as the transmitting UE (Tx-UE), and UE1B as the receiving UE (Rx-UE). As already explained, the PC5 unicast link is bidirectional, and UE1B can also transmit user data and signaling to UE1A over the PC5 unicast link. Therefore, the signaling and operation described below can also be used for DRX performed by UE1A to receive unicast communications (transmits) sent from UE1B.

[0034] In step 501, Tx-UE1A and Rx-UE1B negotiate the DRX configuration for Rx-UE1B to receive unicast communications from Tx-UE1A. In other words, Tx-UE1A and Rx-UE1B determine the DRX configuration for Rx-UE1B to receive unicast communications from Tx-UE1A. To negotiate (or determine) the DRX configuration, Tx-UE1A and Rx-UE1B may exchange bidirectional signaling messages. Tx-UE1A and Rx-UE1B may negotiate (determine) the DRX configuration using RRC layer signaling (e.g., PC5 RRC messages).

[0035] The negotiation (or determination) of this DRX configuration may be performed using a Tx-UE centric or Rx-UE centric method. In Tx-UE centric DRX configuration determination, Rx-UE1B sends assistance information to Tx-UE1A, and Tx-UE1A makes the final decision on the DRX configuration while considering the assistance information. The assistance information sent by Rx-UE1B may include, for example, information about power saving, such as preferences and constraints, or one or both. The assistance information may also include current DRX configurations for one or more other SL connections. More specifically, the assistance information may include a set of DRX configurations for all links where Rx-UE1B has already configured DRX, so that Tx-UE1A can make the decision on behalf of Rx-UE1B.

[0036] In contrast, in Rx-UE centric DRX configuration determination, Tx-UE1A sends assistance information to Rx-UE1B, and Rx-UE1B makes the final decision on the DRX configuration while considering the assistance information. The assistance information sent by Tx-UE1A may include Tx-UE1A's traffic patterns, or it may include one or more DRX configuration candidates that enable Tx-UE1A to satisfy Tx-UE1A's latency requirements for a given traffic pattern.

[0037] In step 501, Tx-UE1A and Rx-UE1B negotiate the DRX settings and then initially activate these valid DRX settings. Activating the DRX settings can also be described as enabling or turning on the DRX settings. That is, Tx-UE1A sends a unicast to Rx-UE1B according to the valid DRX settings for that unicast. Rx-UE1B receives the unicast from Tx-UE1A according to the valid DRX settings.

[0038] As is well known, DRX follows a DRX cycle that includes an ON duration and an OFF duration. The length of the DRX cycle is the sum of the ON duration and the OFF duration. The DRX configuration includes at least information to identify the DRX cycle and the ON duration (or OFF duration). When the DRX configuration is activated, Rx-UE1B attempts to receive unicast transmissions from Tx-UE1A for at least the ON duration, and does not need to do so during the OFF duration. The OFF duration may also be called the Opportunity for DRX. The On Duration may be the period during which the UE waits to receive the Physical Sidelink Control Channel (PSCCH) (and Physical Sidelink Shared Channel (PSSCH)). The PSCCH carries physical layer sidelink control information (SCI). SCI (e.g., SCI format 1) can also be called a scheduling assignment (SA) for PSSCH transmissions. The PSSCH transmits a transport channel (i.e., Sidelink shared channel (SL-SCH)) that carries the transport block to which the SCCH or STCH is mapped. PSCCH is transmitted in the same subframe as the associated PSSCH.

[0039] In step 502, Rx-UE1B, if necessary, indicates to Tx-UE1A whether Rx-UE1B will perform DRX operations based on the valid DRX settings for receiving unicast transmissions from Tx-UE1A while the DRX settings for those unicast transmissions have been negotiated and are valid. Specifically, in the example in Figure 5, Rx-UE1B sends DRX disable information to Tx-UE1A indicating that the DRX operations for the unicast communication based on the valid DRX settings will be temporarily suspended. DRX disable information may also be referred to as DRX deactivation information, DRX OFF information, DRX suspension information, or DRX pause information.

[0040] In response to the transmission of DRX disable information (502), Rx-UE1B temporarily suspends (or pauses) DRX operation for unicast transmissions from Tx-UE1A. In other words, Rx-UE1B attempts to receive on radio resources (e.g., subframes, subchannels, resource blocks) that may be available for unicast transmissions from Tx-UE1A, even during the OFF duration of a valid DRX setting.

[0041] For example, Rx-UE1B may manage multiple active DRX settings for receiving multiple sidelink communications, including unicast communications from Tx-UE1A. In this case, considering multiple DRX settings, situations may arise where Rx-UE1B is (effectively) unable to perform DRX operations or does not require DRX operations. Therefore, if Rx-UE1B is effectively unable to perform DRX operations or does not need to perform DRX operations considering multiple active DRX settings, Rx-UE1B may send DRX disabled information to Tx-UE1A.

[0042] Specifically, the multiple sidelink communications may include, in addition to the unicast communications from Tx-UE1A described above, one or more unicast communications, one or more groupcast communications, one or more broadcast communications, or any combination thereof. The multiple sidelink communications may also include other unicast communications from Tx-UE1A. These may be, for example, unicast communications for sidelink QoS flow(s) that have a different Quality of Service (QoS) profile than those of the sidelink QoS flow(s) transmitted in the unicast communications described above. Rx-UE1B may perform DRX operation based on multiple DRX settings as follows: For example, the RRC layer of Rx-UE1B may configure DRX operation based on multiple DRX settings in one or both of the MAC layer and / or PHY layer. Alternatively, the MAC layer of Rx-UE1B may receive multiple DRX settings from the RRC layer and control the PHY layer to perform DRX operation based on these multiple DRX settings. If, considering multiple valid DRX settings, Rx-UE1B is effectively unable or unnecessary to perform DRX operation, Rx-UE1B may send DRX disabled information to Tx-UE1A.

[0043] On the other hand, upon receiving DRX disable information (502), Tx-UE1A recognizes that Rx-UE1B will perform continuous reception without performing DRX operation based on the enabled DRX setting. For example, Tx-UE1A may transmit to Rx-UE1B even during the OFF duration of the enabled DRX setting. This may contribute to increasing the transmission opportunities for Tx-UE1A.

[0044] The transmission of DRX disable information (502) and the subsequent actions of Tx-UE1A and Rx-UE1B can bring the following advantages. Firstly, it can help avoid an increase in the load on Rx-UE1B (as well as Tx-UE1A and other Tx-UE(s)). For example, considering multiple DRX settings for receiving multiple sidelink communications, there may be situations where Rx-UE1B is effectively unable to perform DRX operations or does not require DRX operations. However, such situations are expected to occur only temporarily. Therefore, Rx-UE1B may be able to resume DRX operations once some sidelink communications have ended. In this case, if Rx-UE1B had to reconfigure, re-determine, and re-negotiate one or more DRX settings for one or more unicast communications, including unicast communications from Tx-UE1A, this could lead to an increase in the load on Rx-UE1B (as well as Tx-UE1A and other Tx-UE(s)). In contrast, the transmission of DRX disable information (502) and the subsequent actions of Tx-UE1A and Rx-UE1B allow Rx-UE1B (and Tx-UE1A and other Tx-UE(s)) to refrain from resetting, re-determining, and renegotiating the DRX settings.

[0045] Secondly, as already mentioned, this could potentially contribute to increasing the transmission opportunities of Tx-UE1A. For example, Tx-UE1A may transmit to Rx-UE1B even during the OFF duration of the valid DRX setting.

[0046] Rx-UE1B may transmit DRX disable information (502) via RRC layer signaling (e.g., PC5 RRC message). Alternatively, Rx-UE1B may transmit DRX disable information (502) via MAC layer signaling (e.g., MAC control element (CE)). Furthermore, Rx-UE1B may transmit DRX disable information (502) via PHY layer signaling.

[0047] As shown in step 503 of Figure 5, after sending DRX disable information (502), Rx-UE1B may, if necessary, send DRX enable information to Tx-UE1A indicating that DRX operation based on a valid DRX configuration will be resumed. For example, when Rx-UE1B is ready to perform DRX operation again, Rx-UE1B may send DRX enable information (503). DRX enable information may also be referred to as DRX activation information, DRX ON information, or DRX resumption information. In response to sending DRX enable information (503), Rx-UE1B reactivates a valid DRX configuration and receives unicast transmissions from Tx-UE1A according to that valid DRX configuration. Meanwhile, in response to receiving DRX enable information (503), Tx-UE1A makes a unicast transmission to Rx-UE1B according to the valid DRX configuration for that unicast transmission.

[0048] In some implementations, the transmission of DRX enable information (503) may be omitted. For example, Rx-UE1B may start a timer in response to the transmission of DRX disable information (502) and activate the DRX setting locally in Rx-UE1B upon completion of the timer. Similarly, Tx-UE1A may start a timer in response to the reception of DRX disable information (502) and activate the DRX setting locally in Tx-UE1A upon completion of the timer.

[0049] The DRX disable information (502) may include additional information (e.g., cause value) to inform Tx-UE1A why DRX operation is temporarily suspended (or a valid DRX setting is temporarily disabled). For example, the additional information may indicate whether the reason for the suspension of DRX operation is that Rx-UE1B is unable to perform DRX (or does not require DRX) due to receiving many sidelinks, or for other reasons. Based on the reason indicated by the additional information, Tx-UE1A may determine whether it is necessary to reconfigure, re-determine, or re-negotiate a valid DRX setting.

[0050] Figure 6 shows an example in which Rx-UE1B receives multiple sidelink unicast communications. In step 601, Tx-UE1A and Rx-UE1B establish a PC5 unicast link and establish (or are considered to have established) a corresponding PC5-RRC connection. In step 602, Tx-UE1A and Rx-UE1B negotiate and initially activate a DRX via signaling over the PC5-RRC connection. That is, Tx-UE1A sends a unicast to Rx-UE1B according to the valid DRX settings for that unicast transmission. Rx-UE1B receives the unicast transmission from Tx-UE1A according to the valid DRX settings.

[0051] In step 603, Rx-UE1B establishes a PC5 unicast link with the other Tx-UE1C and establishes (or is considered to have established) a corresponding PC5-RRC connection. In step 604, Tx-UE1C and Rx-UE1B negotiate a DRX via signaling over the PC5-RRC connection and initially activate it.

[0052] In step 605, Rx-UE1B decides to temporarily disable DRX operation. For example, Rx-UE1B may temporarily disable DRX operation if it is appropriate for Rx-UE1B to perform continuous reception to receive multiple sidelink communications, including unicast communications from Tx-UE1A and Tx-UE1C, respectively. In steps 606 and 607, Rx-UE1B sends DRX disable information to Tx-UE1A and Tx-UE1C. The order of steps 606 and 607 is not particularly limited.

[0053] In step 608, Rx-UE1B releases the PC5 unicast link and PC5-RRC connection with Tx-UE1C. In step 609, Rx-UE1B decides to resume DRX operation. For example, Rx-UE1B may resume DRX operation if it is appropriate for Rx-UE1B to perform DRX in order to receive one or more sidelink communications, including unicast communications from Tx-UE1A. In step 610, Rx-UE1B sends DRX enable information to Tx-UE1A. Note that in step 608, the PC5 unicast link and PC5-RRC connection do not necessarily have to be released. For example, Rx-UE1B may perform the action in step 610 if it determines that it is appropriate to perform DRX because the Rx-UE1B's DRX settings have been changed to receive unicast transmissions from Tx-UE1C.

[0054] Figure 7 shows an example in which Rx-UE1B receives a sidelink broadcast or sidelink groupcast in addition to performing sidelink unicast communication. Steps 701 and 702 are the same as steps 601 and 602 in Figure 6.

[0055] In step 703, the Rx-UE1B begins receiving sidelink broadcasts or sidelink groupcasts.

[0056] In step 704, Rx-UE1B decides to temporarily disable DRX operation. For example, Rx-UE1B may temporarily disable DRX operation if it is appropriate for Rx-UE1B to perform continuous reception to receive multiple sidelink communications, including sidelink unicast and sidelink broadcast (or broadcast) from Tx-UE1A. In step 705, Rx-UE1B sends DRX disable information to Tx-UE1A.

[0057] In step 706, Rx-UE1B terminates receiving sidelink broadcasts or sidelink groupcasts. In step 707, Rx-UE1B decides to resume DRX operation. For example, Rx-UE1B may resume DRX operation if it is appropriate for it to perform DRX to receive one or more sidelink communications, including unicast communications from Tx-UE1A. In step 708, Rx-UE1B sends DRX enable information to Tx-UE1A.

[0058] <Second Embodiment> This embodiment describes a modification of the signaling for DRX described in the first embodiment. An example of a wireless communication system according to this embodiment is the same as the example described with reference to Figure 1.

[0059] The following section, with reference to Figure 8, describes a specific example of DRX signaling by UE1B for receiving unicast communications (transmits) sent from UE1A. For convenience of explanation, UE1A will be referred to as the transmitting UE (Tx-UE), and UE1B as the receiving UE (Rx-UE). As already explained, the PC5 unicast link is bidirectional, and UE1B can also transmit user data and signaling to UE1A over the PC5 unicast link. Therefore, the signaling and operation described below can also be used for DRX performed by UE1A to receive unicast communications (transmits) sent from UE1B.

[0060] In step 801, similar to step 501 in Figure 5, Tx-UE1A and Rx-UE1B negotiate the DRX settings for Rx-UE1B to receive unicast communications from UE1A. Tx-UE1A and Rx-UE1B may negotiate (determine) the DRX settings using RRC layer signaling (e.g., PC5 RRC messages). This negotiation (or determination) of the DRX settings may be performed using a Tx-UE centric method or an Rx-UE centric method.

[0061] However, in step 801, in contrast to the operation in step 501, Tx-UE1A and Rx-UE1B initially deactivate the valid DRX setting after negotiating it. Deactivating a DRX setting can also be rephrased as disabling or turning off the DRX setting. That is, Rx-UE1B has a valid DRX setting but does not initiate DRX operation based on that DRX setting. Tx-UE1A recognizes that Rx-UE1B has a valid DRX setting but has not yet initiated DRX operation.

[0062] In step 802, Rx-UE1B indicates to Tx-UE1A whether Rx-UE1B will perform DRX operations based on the valid DRX settings to receive the unicast transmission from Tx-UE1A, while the DRX settings for the unicast transmission from Tx-UE1A are negotiated and valid. Specifically, in the example in Figure 8, Rx-UE1B sends DRX enable information to Tx-UE1A indicating that DRX operations for the unicast transmission based on the valid DRX settings will be initiated. DRX enable information may also be referred to as DRX activation information, DRX ON information, or DRX resumption information.

[0063] Upon receiving DRX enable information (802), Rx-UE1B activates a valid DRX configuration and receives unicast transmissions from Tx-UE1A according to that valid DRX configuration. Conversely, upon receiving DRX enable information (802), Tx-UE1A sends a unicast transmission to Rx-UE1B according to the valid DRX configuration for that unicast transmission.

[0064] The transmission of DRX enable information (802) and the subsequent actions of Tx-UE1A and Rx-UE1B offer the following advantages: Upon receiving DRX enable information (802), Tx-UE1A will perform a unicast transmission to Rx-UE1B according to the valid DRX settings for that unicast transmission. In other words, Tx-UE1A will not recognize that Rx-UE1B is performing DRX operation unless it receives DRX enable information (802) from Rx-UE1B. This allows Tx-UE1A and Rx-UE1B to successfully perform sidelink unicast communication even if Tx-UE1A supports sidelink DRX operation but Rx-UE1B does not.

[0065] As shown in step 803 of Figure 8, after sending the DRX enable information (802), Rx-UE1B may optionally send DRX disable information to Tx-UE1A indicating that DRX operation based on a valid DRX configuration will be temporarily suspended. The behavior of Tx-UE1A and Rx-UE1B after sending the DRX disable information (803) may be the same as the behavior of Tx-UE1A and Rx-UE1B after sending the DRX disable information in step 502 of Figure 5.

[0066] In some implementations, the transmission of DRX disable information (803) may be omitted. For example, Rx-UE1B may continue DRX operation based on the valid DRX setting until the DRX setting is disabled or released via signaling between Tx-UE1A and Rx-UE1B for reconfiguration of the PC5 RRC connection.

[0067] <Third Embodiment> This embodiment describes a modification of the signaling for DRX described in the first embodiment. An example of a wireless communication system according to this embodiment is the same as the example described with reference to Figure 1.

[0068] Figure 9 shows an example of signaling involved in the procedure for Tx-UE1A and Rx-UE1B to negotiate the DRX configuration for Rx-UE1B to receive unicast communications from UE1A. The signaling in Figure 9 relates to the negotiation (or determination) of the Tx-UE centric DRX configuration. In step 901, Tx-UE1A finalizes the DRX configuration and sends it to Rx-UE1B. In one example, Tx-UE1A may send the DRX configuration using the RRCReconfigurationSidelink message, as shown in Figure 9. Prior to step 901, Rx-UE1B may send assistance information to Tx-UE1A. Tx-UE1A may make the final decision on the DRX configuration while considering the received assistance information. The assistance information may include, for example, information about power saving, such as preferences and constraints, or one or both. The assistance information may include current DRX configurations for one or more other SL connections.

[0069] In step 902, Rx-UE1B decides to accept (or follow) the configuration (including the DRX configuration) contained in the RRC message (e.g., RRCReconfigurationSidelink message) received in step 901. Then, Rx-UE1B responds to Tx-UE1A with an acknowledgment. Specifically, Rx-UE1B may send an RRCReconfigurationCompleteSidelink message to Tx-UE1A.

[0070] The message in step 902 indicates to Tx-UE1A whether Rx-UE1B will perform a DRX operation based on the DRX configuration received in step 901 in order to receive the corresponding unicast transmission from Tx-UE1A. For example, if Rx-UE1B performs a DRX operation based on the DRX configuration, Rx-UE1B may include DRX enable information in the message in step 902. Alternatively, if Rx-UE1B performs a DRX operation based on the DRX configuration, Rx-UE1B may not include DRX disable information in the message in step 902. On the other hand, if Rx-UE1B does not perform a DRX operation based on the DRX configuration, Rx-UE1B may include DRX disable information in the message in step 902. Alternatively, if Rx-UE1B does not perform a DRX operation based on the DRX configuration, Rx-UE1B may not include DRX enable information in the message in step 902.

[0071] If the message in step 902 indicates that DRX operation will be performed, Tx-UE1A will send a unicast to Rx-UE1B according to the valid DRX settings for that unicast. Rx-UE1B will receive the unicast from Tx-UE1A according to the valid DRX settings. Conversely, if the message in step 902 indicates that DRX operation will not be performed, Rx-UE1B has a valid DRX setting but will not initiate DRX operation based on that DRX setting. Tx-UE1A recognizes that Rx-UE1B has a valid DRX setting but has not yet initiated DRX operation.

[0072] According to the signaling shown in Figure 9, Rx-UE1B can determine whether the valid DRX configuration negotiated with Tx-UE1A is initially activated or deactivated, and inform Tx-UE1A of this.

[0073] <Fourth Embodiment> This embodiment describes a modification of the signaling for DRX described in the first embodiment. An example of a wireless communication system according to this embodiment is the same as the example described with reference to Figure 1.

[0074] The following section, with reference to Figure 10, describes a specific example of DRX signaling by UE1B for receiving unicast communications (transmits) sent from UE1A. For convenience of explanation, UE1A will be referred to as the transmitting UE (Tx-UE), and UE1B as the receiving UE (Rx-UE). As already explained, the PC5 unicast link is bidirectional, and UE1B can also transmit user data and signaling to UE1A over the PC5 unicast link. Therefore, the signaling and operation described below can also be used for DRX performed by UE1A to receive unicast communications (transmits) sent from UE1B.

[0075] Step 1001 is similar to step 501 in Figure 5. Specifically, the DRX configuration is negotiated and initially activated.

[0076] In step 1001, Tx-UE1A indicates to Rx-UE1B whether or not it is permitted to perform DRX operations based on the valid DRX settings for receiving unicast transmissions from Tx-UE1A, while the DRX settings for unicast transmissions from Tx-UE1A are negotiated and valid. In other words, Rx-UE1B receives information from Tx-UE1A indicating whether or not it is permitted to perform DRX operations based on the valid DRX settings for unicast transmissions from Tx-UE1A, while the DRX settings for unicast transmissions from Tx-UE1A are negotiated and valid.

[0077] Specifically, in the example shown in Figure 10, Tx-UE1A sends DRX disable information to Rx-UE1B indicating that the DRX operation for the unicast communication based on the valid DRX setting needs to be temporarily suspended. DRX disable information may also be referred to as DRX deactivation information, DRX OFF information, DRX suspension information, or DRX pause information.

[0078] Upon receiving DRX disable information (1002), Tx-UE1A recognizes that Rx-UE1B will perform continuous reception without performing DRX operation based on the valid DRX setting. On the other hand, upon receiving DRX disable information (1002), Rx-UE1B temporarily stops (or suspends, pauses) the DRX operation for unicast transmission from Tx-UE1A. In other words, Rx-UE1B attempts to receive on radio resources (e.g., subframes, subchannels, resource blocks) that can be used for unicast transmission from Tx-UE1A, even during the OFF duration of the valid DRX setting.

[0079] For example, after sending DRX disable information (1002), Tx-UE1A may send a transmission to Rx-UE1B even during the OFF duration of the valid DRX setting. This could potentially increase the transmission opportunities for Tx-UE1A.

[0080] As shown in step 1003 of Figure 10, after sending DRX disable information (1002), Tx-UE1A may, if necessary, send DRX enable information to Rx-UE1B indicating that DRX operation based on a valid DRX setting will be resumed. DRX enable information may also be referred to as DRX activation information, DRX ON information, or DRX resumption information, for example.

[0081] In some implementations, the transmission of DRX enable information (1003) may be omitted. For example, Tx-UE1A may start a timer in response to the transmission of DRX disable information (1002) and activate the DRX setting locally in Tx-UE1A upon completion of the timer. Similarly, Rx-UE1B may start a timer in response to the reception of DRX disable information (1002) and activate the DRX setting locally in Rx-UE1B upon completion of the timer.

[0082] The DRX disable information (1002) may include additional information (e.g., cause value) to inform the Rx-UE1B why the DRX operation is temporarily suspended (or an active DRX setting is temporarily disabled). For example, this additional information may indicate whether the reason for the suspension of DRX operation is that urgent information needs to be sent or for some other reason.

[0083] <Fifth Embodiment> This embodiment describes a modification of the signaling for DRX described in the first embodiment. An example of a wireless communication system according to this embodiment is the same as the example described with reference to Figure 1.

[0084] The following section, with reference to Figure 11, describes a specific example of DRX signaling by UE1B for receiving unicast communications (transmits) sent from UE1A. For convenience of explanation, UE1A will be referred to as the transmitting UE (Tx-UE), and UE1B as the receiving UE (Rx-UE). As already explained, the PC5 unicast link is bidirectional, and UE1B can also transmit user data and signaling to UE1A over the PC5 unicast link. Therefore, the signaling and operation described below can also be used for DRX performed by UE1A to receive unicast communications (transmits) sent from UE1B.

[0085] Step 1101 is similar to step 801 in Figure 8. Specifically, the DRX configuration is negotiated and then deactivated.

[0086] In step 1102, Tx-UE1A indicates to Rx-UE1B whether Rx-UE1B is permitted to perform DRX operations based on the valid DRX settings for receiving unicast transmissions from Tx-UE1A, while the DRX settings for unicast transmissions from Tx-UE1A are negotiated and valid. Specifically, in the example in Figure 11, Tx-UE1A sends DRX enable information to Rx-UE1B indicating that Rx-UE1B is permitted to perform DRX operations based on the valid DRX settings. DRX enable information may also be referred to as DRX activation information, DRX ON information, or DRX resumption information.

[0087] In response to the transmission of DRX enable information (1102), Tx-UE1A performs a unicast transmission to Rx-UE1B according to the valid DRX settings for that unicast transmission. Meanwhile, Rx-UE1B activates the valid DRX settings and receives the unicast transmission from Tx-UE1A according to those valid DRX settings.

[0088] The transmission of DRX enable information (1102) and the subsequent operation of Tx-UE1A and Rx-UE1B offer the following advantages: Upon receiving DRX enable information (1102), Rx-UE1B receives unicast transmissions from Tx-UE1A according to the valid DRX settings for those unicast transmissions. In other words, Rx-UE1B will not perform DRX to receive unicast transmissions from Tx-UE1A unless it receives DRX enable information (1102) from Tx-UE1A. This allows Tx-UE1A and Rx-UE1B to successfully perform sidelink unicast communication even if Rx-UE1B supports sidelink DRX operation but Tx-UE1A does not.

[0089] As shown in step 1103 of Figure 11, after sending the DRX enable information (1102), Tx-UE1A may, if necessary, send DRX disable information to Rx-UE1B indicating that DRX operation based on a valid DRX configuration needs to be temporarily suspended. The behavior of Tx-UE1A and Rx-UE1B after sending the DRX disable information (1103) may be the same as the behavior of Tx-UE1A and Rx-UE1B after sending the DRX disable information in step 1002 of Figure 10.

[0090] In some implementations, the transmission of DRX disable information (1103) may be omitted. For example, Rx-UE1B may continue DRX operation based on the valid DRX setting until the DRX setting is disabled or released via signaling between Tx-UE1A and Rx-UE1B for reconfiguration of the PC5 RRC connection.

[0091] Next, the following describes configuration examples of UE1 according to the multiple embodiments described above. Figure 12 is a block diagram showing a configuration example of UE1. Both UE1A as Tx-UE and UE1B as Rx-UE described above may have the configuration shown in Figure 12. The Radio Frequency (RF) transceiver 1201 performs analog RF signal processing to communicate with the RAN node. The RF transceiver 1201 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1201 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1201 is coupled with the antenna array 1202 and the baseband processor 1203. The RF transceiver 1201 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1203, generates a transmit RF signal, and supplies the transmit RF signal to the antenna array 1202. Furthermore, the RF transceiver 1201 generates a baseband received signal based on the received RF signal received by the antenna array 1202 and supplies it to the baseband processor 1203. The RF transceiver 1201 may also include an analog beamformer circuit for beamforming. The analog beamformer circuit may include, for example, multiple phase shifters and multiple power amplifiers.

[0092] The baseband processor 1203 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of transmission format (transmission frame), (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). Control plane processing, on the other hand, includes communication management at Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attach, mobility, and call management).

[0093] For example, the digital baseband signal processing by the baseband processor 1203 may include signal processing for the Service Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and Physical (PHY) layer. Furthermore, the control plane processing by the baseband processor 1203 may include processing for the Non-Access Stratum (NAS) protocol, Radio Resource Control (RRC) protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs).

[0094] The baseband processor 1203 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.

[0095] The baseband processor 1203 may include a modem processor (e.g., Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1204 described later.

[0096] The application processor 1204 is also called a CPU, MPU, microprocessor, or processor core. The application processor 1204 may include multiple processors (multiple processor cores). The application processor 1204 implements various functions of the UE1 by executing system software programs (Operating System (OS)) and various application programs (e.g., calling applications, web browsers, mail clients, camera operation applications, music playback applications) read from memory 1206 or memory not shown.

[0097] In some implementations, the baseband processor 1203 and the application processor 1204 may be integrated on a single chip, as shown by the dashed line (1205) in Figure 12. In other words, the baseband processor 1203 and the application processor 1204 may be implemented as a single System on Chip (SoC) device 1205. An SoC device is sometimes called a System Large Scale Integration (LSI) or chipset.

[0098] Memory 1206 is volatile memory, non-volatile memory, or a combination thereof. Memory 1206 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory is Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. For example, memory 1206 may include an external memory device accessible from the baseband processor 1203, the application processor 1204, and the SoC 1205. Memory 1206 may also include an internal memory device integrated within the baseband processor 1203, the application processor 1204, or the SoC 1205. Furthermore, memory 1206 may include memory within a Universal Integrated Circuit Card (UICC).

[0099] Memory 1206 may store one or more software modules (computer programs) 1207 containing instruction sets and data for performing the processing by UE1 as described in the above embodiments. In some implementations, the baseband processor 1203 or application processor 1204 may be configured to read and execute the software modules 1207 from memory 1206 to perform the processing of UE1 as described with reference to the drawings in the above embodiments.

[0100] Furthermore, the control plane processing and operation performed by the UE1 described in the above embodiment can be realized by other elements other than the RF transceiver 1201 and antenna array 1202, namely at least one of the baseband processor 1203 and application processor 1204 and the memory 1206 storing the software module 1207.

[0101] As illustrated with reference to Figure 12, one or more processors in the UE1 according to the above embodiment can execute one or more programs, which include a set of instructions for causing a computer to perform the algorithms described with reference to the drawings. The program includes a set of instructions (or software code) for causing a computer to perform one or more functions described in the embodiment when loaded into a computer. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited, of the computer-readable medium or physical storage medium include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited, of the temporary computer-readable medium or communication medium include electrical, optical, acoustic or other forms of propagating signals.

[0102] The embodiments described above are merely examples of how the technical concept obtained by the present inventor can be applied. In other words, the technical concept is not limited to the embodiments described above, and various modifications are certainly possible.

[0103] For example, some or all of the above embodiments may also be described as follows, but are not limited to the following.

[0104] (Note 1) A wireless terminal, At least one wireless transceiver, The system comprises at least one processor coupled to the at least one wireless transceiver, The aforementioned at least one processor is Negotiate with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communication by the wireless terminal on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and valid, the system is configured to indicate to the peer terminal whether the wireless terminal will perform DRX operations based on the valid DRX setting in order to receive the unicast communication. Wireless terminal. (Note 2) The DRX operation based on the above valid DRX settings is initially activated, The at least one processor is configured to send disable information to the peer terminal indicating that the DRX operation based on the valid DRX setting is temporarily suspended. The wireless terminal described in Appendix 1. (Note 3) The aforementioned at least one processor is It manages multiple valid DRX settings for receiving each of the multiple sidelink communications, including the aforementioned unicast communications. If, considering the multiple valid DRX settings, the wireless terminal is substantially unable or unnecessary to perform DRX operation, it is configured to transmit the disable information to the peer terminal. The wireless terminal described in Appendix 2. (Note 4) The at least one processor is configured to, after transmitting the disable information, transmit enable information to the peer terminal, if necessary, indicating that the DRX operation based on the valid DRX setting will be resumed. Wireless terminal as described in Appendix 2 or 3. (Note 5) The DRX operation based on the above valid DRX settings is initially deactivated. The at least one processor is configured to send enable information to the peer terminal indicating that the DRX operation based on the valid DRX setting is initiated. The wireless terminal described in Appendix 1. (Note 6) The at least one processor is configured to, after transmitting the enable information, optionally transmit disable information to the peer terminal indicating that the DRX operation based on the valid DRX setting is temporarily suspended. The wireless terminal described in Appendix 5. (Note 7) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The system is configured to transmit information to the peer terminal via RRC layer signaling indicating whether or not the wireless terminal performs the DRX operation based on the valid DRX settings. A wireless terminal as described in any one of the items 1 to 6 in the appendix. (Note 8) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The system is configured to transmit information to the peer terminal via Medium Access Control (MAC) layer signaling indicating whether or not the wireless terminal performs the DRX operation based on the valid DRX settings. A wireless terminal as described in any one of the items 1 to 6 in the appendix. (Note 9) A wireless terminal, At least one wireless transceiver, The system comprises at least one processor coupled to the at least one wireless transceiver, The aforementioned at least one processor is Negotiate with the peer terminal the discontinuous reception (DRX) setting for the peer terminal's reception of unicast communication on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and valid, the system is configured to receive first information from the peer terminal indicating whether or not the peer terminal will perform a DRX operation based on the valid DRX setting in order to receive the unicast communication. Wireless terminal. (Note 10) The DRX operation based on the above valid DRX settings is initially activated, The at least one processor is configured to recognize that if the first information indicates that the DRX operation based on the valid DRX setting is temporarily suspended, the peer terminal will perform a continuous receive operation without performing the DRX operation based on the valid DRX setting. The wireless terminal described in Appendix 9. (Note 11) The DRX operation based on the above valid DRX settings is initially deactivated. The at least one processor is configured to perform the transmission relating to the unicast communication while taking the valid DRX setting into consideration if the first information indicates that the DRX operation based on the valid DRX setting is to be initiated. The wireless terminal described in Appendix 9. (Note 12) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The first information is configured to be received from the peer terminal via RRC layer signaling. A wireless terminal as described in any one of the items 9 to 11 in the appendix. (Note 13) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The system is configured to receive the aforementioned first information from the peer terminal using Medium Access Control (MAC) layer signaling. A wireless terminal as described in any one of the items 9 to 11 in the appendix. (Note 14) A method performed by a wireless terminal, Negotiate with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communication by the wireless terminal on the direct interface between the wireless terminal and the peer terminal, and While the DRX setting is negotiated and valid, the peer terminal is informed whether or not the wireless terminal will perform DRX operations based on the valid DRX setting in order to receive the unicast communication. A method for providing this. (Note 15) A method performed by a wireless terminal, Negotiate with the peer terminal the discontinuous reception (DRX) setting for the peer terminal's reception of unicast communication on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and valid, receive first information from the peer terminal indicating whether or not the peer terminal will perform a DRX operation based on the valid DRX setting in order to receive the unicast communication. A method for providing this. (Note 16) A program for causing a computer to perform a method for wireless terminals, The aforementioned method, Negotiate with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communication by the wireless terminal on the direct interface between the wireless terminal and the peer terminal, and While the DRX setting is negotiated and valid, the peer terminal is informed whether or not the wireless terminal will perform DRX operations based on the valid DRX setting in order to receive the unicast communication. A program that includes the following features. (Note 17) A program for causing a computer to perform a method for wireless terminals, The aforementioned method, Negotiate with the peer terminal the discontinuous reception (DRX) setting for the peer terminal's reception of unicast communication on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and valid, receive first information from the peer terminal indicating whether or not the peer terminal will perform a DRX operation based on the valid DRX setting in order to receive the unicast communication. A program that includes the following features. (Note 18) A wireless terminal, At least one wireless transceiver, The system comprises at least one processor coupled to the at least one wireless transceiver, The aforementioned at least one processor is Negotiate with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communication by the wireless terminal on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and active, the wireless terminal is configured to receive first information from the peer terminal indicating whether or not it is permitted to perform DRX operations based on the active DRX setting in order to receive the unicast communication. Wireless terminal. (Note 19) The DRX operation based on the above valid DRX settings is initially activated, The at least one processor is configured to perform continuous reception without performing DRX operation based on the valid DRX setting if the first information indicates that the DRX operation based on the valid DRX setting needs to be temporarily suspended. The wireless terminal described in Appendix 18. (Note 20) The DRX operation based on the above valid DRX settings is initially deactivated. The at least one processor is configured to initiate the DRX operation based on the valid DRX setting to receive the unicast communication if the first information indicates that the wireless terminal is permitted to perform the DRX operation. The wireless terminal described in Appendix 18. (Note 21) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The first information is configured to be received from the peer terminal via RRC layer signaling. A wireless terminal as described in any one of the items 18-20 of the appendix. (Note 22) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The system is configured to receive the aforementioned first information from the peer terminal using Medium Access Control (MAC) layer signaling. A wireless terminal as described in any one of the items 18-20 of the appendix. (Note 23) A wireless terminal, At least one wireless transceiver, The system comprises at least one processor coupled to the at least one wireless transceiver, The aforementioned at least one processor is Negotiate with the peer terminal the discontinuous reception (DRX) setting for the peer terminal's reception of unicast communication on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and valid, the system is configured to indicate to the peer terminal whether or not it is permitted to perform DRX operations based on the valid DRX setting in order to receive the unicast communication. Wireless terminal. (Note 24) The DRX operation based on the above valid DRX settings is initially activated, The at least one processor is configured to send disable information to the peer terminal indicating that the DRX operation based on the valid DRX setting needs to be temporarily suspended. The wireless terminal described in Appendix 23. (Note 25) The disabled information causes the peer terminal to perform continuous reception without performing DRX operation based on the valid DRX setting. The wireless terminal described in Appendix 24. (Note 26) The DRX operation based on the above valid DRX settings is initially deactivated. The at least one processor is configured to send enable information to the peer terminal indicating that the DRX operation based on the valid DRX setting is permitted. The wireless terminal described in Appendix 23. (Note 27) The at least one processor is configured to, after transmitting the enable information, transmit disable information to the peer terminal, if necessary, indicating that the DRX operation based on the valid DRX setting needs to be temporarily suspended. The wireless terminal described in Appendix 26. (Note 28) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The system is configured to send information to the peer terminal via RRC layer signaling indicating whether or not the peer terminal is permitted to perform DRX operations based on the valid DRX settings. A wireless terminal as described in any one of the items 23 to 27 of the appendix. (Note 29) The aforementioned at least one processor is The DRX settings are negotiated using Radio Resource Control (RRC) layer signaling with the peer terminal. The system is configured to send information to the peer terminal via Medium Access Control (MAC) layer signaling indicating whether or not the peer terminal is permitted to perform DRX operations based on the valid DRX settings. A wireless terminal as described in any one of the items 23 to 27 of the appendix. (Note 30) A method performed by a wireless terminal, Negotiate with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communication by the wireless terminal on the direct interface between the wireless terminal and the peer terminal, and While the DRX setting is negotiated and active, the wireless terminal receives first information from the peer terminal indicating whether or not it is permitted to perform DRX operations based on the active DRX setting in order to receive the unicast communication. A method for providing this. (Note 31) A method performed by a wireless terminal, Negotiate with the peer terminal the discontinuous reception (DRX) setting for the peer terminal's reception of unicast communication on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and valid, the peer terminal is indicated whether or not it is permitted to perform DRX operations based on the valid DRX setting in order to receive the unicast communication. A method for providing this. (Note 32) A program for causing a computer to perform a method for wireless terminals, The aforementioned method, Negotiate with the peer terminal a discontinuous reception (DRX) setting for the reception of unicast communication by the wireless terminal on the direct interface between the wireless terminal and the peer terminal, and While the DRX setting is negotiated and active, the wireless terminal receives first information from the peer terminal indicating whether or not it is permitted to perform DRX operations based on the active DRX setting in order to receive the unicast communication. A program that includes the following features. (Note 33) A program for causing a computer to perform a method for wireless terminals, The aforementioned method, Negotiate with the peer terminal the discontinuous reception (DRX) setting for the peer terminal's reception of unicast communication on the direct interface between the wireless terminal and the peer terminal. While the DRX setting is negotiated and valid, the peer terminal is indicated whether or not it is permitted to perform DRX operations based on the valid DRX setting in order to receive the unicast communication. A program that includes the following features.

[0105] This application claims priority based on Japanese Patent Application No. 2021-107507, filed on 29 June 2021, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0106] 1 UE 2 RANNodes 21 cells 103 UE-to-UE direct interface 1203 Baseband Processor 1204 Application Processor 1206 memory 1207 Module

Claims

1. The first wireless terminal, A receiving means for receiving a first message from a second wireless terminal, which includes settings related to sidelinks, including Discontinuous Reception (DRX) settings set by the second wireless terminal, The system includes a transmission means for transmitting a second message to the second wireless terminal indicating acceptance of the settings relating to the side link, The second message includes information indicating that the first wireless terminal rejects the DRX setting, if the first wireless terminal rejects the DRX setting. The first wireless terminal.

2. The transmitting means, when the first wireless terminal accepts the DRX setting set by the second wireless terminal, transmits the second message without including information indicating that the DRX setting set by the second wireless terminal is rejected. The first wireless terminal according to claim 1.

3. A method in a first wireless terminal, Receiving a first message from a second wireless terminal, which includes settings related to sidelinks, including Discontinuous Reception (DRX) settings configured by the second wireless terminal, The system includes transmitting a second message to the second wireless terminal indicating that it accepts the settings relating to the side link, The second message includes information indicating that the first wireless terminal rejects the DRX setting, if the first wireless terminal rejects the DRX setting. A first wireless terminal method.

4. If the first wireless terminal accepts the DRX setting set by the second wireless terminal, it sends the second message without including information indicating that it rejects the DRX setting set by the second wireless terminal. The method according to claim 3.

Images