METHOD AND APPARATUS FOR DETERMINING A SIDELINK DRX CONFIGURATION - Patent application

Abstract

The present application relates to a method and apparatus for determining a sidelink (SL) discontinuous reception (DRX) configuration. One embodiment of the present disclosure provides a method performed by a first user equipment (UE), the method including: transmitting, to a second UE, assistance information related to the SL DRX configuration of the first UE, the assistance information being included in a SL UE Capability Information message of the first UE also transmitted to the second UE or included in a separate Radio Resource Control (RRC) message also transmitted to the second UE; and receiving, from the second UE, a SL DRX configuration based on the assistance information transmitted to the second UE.

Description

[Technical Field]

[0001] The present disclosure relates generally to sidelink (SL) communications, and more particularly to methods and apparatus for determining a SL discontinuous reception (DRX) configuration. [Background technology]

[0002] Vehicle-to-everything (V2X) is being introduced in 5G wireless communication technology. Regarding the channel structure of V2X communication, the direct link between two user equipments (UEs) is called sidelink (SL). Sidelink is a feature of long-term evolution (LTE) introduced in 3GPP (3rd Generation Partnership Project) Release 12 that enables direct communication between nearby UEs, without the need for data to pass through a base station (BS) or core network. Summary of the Invention [Problem to be solved by the invention]

[0003] To improve the reliability of SL communication, it is desirable to determine the SL DRX configuration before performing SL communication. [Means for solving the problem]

[0004] Some embodiments of the present disclosure provide a method performed by a first UE, the method including the steps of: transmitting, to a second UE, assistance information related to an SL DRX configuration of the first UE, wherein the assistance information is included in an SL UE Capability Information message of the first UE also transmitted to the second UE, or is included in a separate radio resource control (RRC) message also transmitted to the second UE; and receiving, from the second UE, the SL DRX configuration based on the assistance information transmitted to the second UE.

[0005] In certain embodiments of the present disclosure, the assistance information includes at least one of a request for an SL DRX configuration, a Uu DRX configuration of the first UE, one or more DRX configurations for one or more other links of the first UE, one or more SL DRX configurations preferred or proposed by the first UE, or an acceptance or rejection of an SL DRX configuration received from the second UE.

[0006] In some embodiments of the present disclosure, the assistance information is transmitted periodically.

[0007] In an embodiment of the present disclosure, the assistance information is transmitted in at least one of the following cases: when the first UE has one or more preferred SL DRX configurations; when the assistance information of the first UE is updated; when the operation state of the first UE changes; or when the first UE receives a request for assistance information from the second UE.

[0008] In an embodiment of the present disclosure, the request for assistance information includes a one-bit indication or list of DRX configurations proposed by the second UE.

[0009] In an embodiment of the present disclosure, the assistance information included in the SL UE Capability Information message of the first UE includes a one-bit request for SL DRX configuration or an index of the SL DRX configuration proposed by the first UE.

[0010] In an embodiment of the present disclosure, the SL UE Capability Information message of the first UE includes an assistance information indicator that indicates that the assistance information should be sent in a separate RRC message.

[0011] In an embodiment of the present disclosure, the method further includes sending a radio resource control (RRC) reconfiguration failure message with an SL DRX configuration failure indication to the second UE if the SL DRX configuration is not applicable and one or more access stratum (AS) configurations received along with the SL DRX configuration are applicable; applying the previous SL DRX configuration until a new RRC reconfiguration message is received; and applying the one or more AS configurations or continuing to apply the previous one or more AS configurations until a new RRC reconfiguration message is received.

[0012] In an embodiment of the present disclosure, the method further includes the steps of: if the SL DRX configuration is applicable and one or more AS configurations received along with the SL DRX configuration are not applicable, sending an RRC reconfiguration failure message without an SL DRX configuration failure indication to the second UE; applying the previous one or more AS configurations until a new RRC reconfiguration message is received; and applying the SL DRX configuration or continuing to apply the previous SL DRX configuration until a new RRC reconfiguration message is received.

[0013] In an embodiment of the present disclosure, the method further includes, if the SL DRX configuration is not applicable and one or more AS configurations received along with the SL DRX configuration are not applicable, sending an RRC reconfiguration failure message with an SL DRX configuration failure indication to the second UE, and continuing to apply the previous SL DRX configuration and the previous one or more AS configurations until a new RRC reconfiguration message is received.

[0014] In an embodiment of the present disclosure, the method further includes, if the SL DRX configuration is applicable and the one or more AS configurations received along with the SL DRX configuration are applicable, sending an RRC reconfiguration complete message to the second UE, and applying both the SL DRX configuration and the one or more AS configurations.

[0015] In an embodiment of the present disclosure, the SL DRX configuration failure indication includes a SL DRX configuration failure cause.

[0016] In an embodiment of the present disclosure, the method further includes sending updated assistance information to the second UE if the SL DRX configuration is not applicable.

[0017] In an embodiment of the present disclosure, the method further includes receiving, from the second UE, an updated SL DRX configuration in response to the SL DRX configuration failure indication.

[0018] In an embodiment of the present disclosure, the first UE and the second UE support SL DRX communication.

[0019] Some embodiments of the present disclosure provide a method performed by a second UE, the method including: receiving, from a first UE, assistance information related to an SL DRX configuration of the first UE, wherein the assistance information is included in an SL UE Capability Information message of the first UE also received from the first UE or is included in a separate Radio Resource Control (RRC) message also received from the first UE; and transmitting, to the first UE, an SL DRX configuration based on the assistance information received from the first UE.

[0020] In certain embodiments of the present disclosure, the assistance information includes at least one of a request for an SL DRX configuration, a Uu DRX configuration of the first UE, one or more DRX configurations for one or more other links of the first UE, one or more SL DRX configurations preferred or proposed by the first UE, or an acceptance or rejection of an SL DRX configuration received from the second UE.

[0021] In some embodiments of the present disclosure, the assistance information is received periodically.

[0022] In an embodiment of the present disclosure, the method further includes transmitting a request for assistance information to the first UE.

[0023] In an embodiment of the present disclosure, the request for assistance information includes a one-bit indication or list of DRX configurations proposed by the second UE.

[0024] In an embodiment of the present disclosure, the assistance information included in the SL UE Capability Information message of the first UE includes a one-bit request for SL DRX configuration or an index of the SL DRX configuration proposed by the first UE.

[0025] In an embodiment of the present disclosure, the SL UE Capability Information message of the first UE includes an assistance information indicator that indicates that the assistance information should be received in a separate RRC message.

[0026] In an embodiment of the present disclosure, the method further includes receiving an RRC reconfiguration failure message with an SL DRX configuration failure indication from the first UE, and transmitting an updated SL DRX configuration to the first UE in response to the SL DRX configuration failure indication.

[0027] In an embodiment of the present disclosure, the method further includes transmitting, to the BS, at least one of updated assistance information from the first UE, an SL DRX configuration failure indication, or an SL DRX configuration failure cause.

[0028] In an embodiment of the present disclosure, the SL DRX configuration failure indication received from the first UE includes a SL DRX configuration failure cause.

[0029] In an embodiment of the present disclosure, a request for assistance information is sent when the operating state of the second UE changes.

[0030] In an embodiment of the present disclosure, the method further includes: obtaining an updated SL DRX configuration when an operation state of the second UE changes; and transmitting the updated SL DRX configuration to the first UE when the updated SL DRX configuration is obtained.

[0031] In an embodiment of the present disclosure, the method further includes transmitting, to the BS, the assistance information received from the first UE to request the SL DRX configuration, and receiving the SL DRX configuration from the BS.

[0032] In an embodiment of the present disclosure, the SL DRX configuration is determined from a set of SL DRX configurations each corresponding to a respective quality of service (QoS) profile, or from a set of common SL DRX configurations.

[0033] In an embodiment of the present disclosure, the set of SL DRX configurations or the set of common SL DRX configurations is pre-configured in the second UE or received in a system information block (SIB) message.

[0034] In an embodiment of the present disclosure, the method further includes, when the second UE is in an RRC idle state or an RRC inactive state, requesting the second UE to enter an RRC connected state upon receiving the assistance information.

[0035] Yet another embodiment of the present disclosure provides an apparatus, the apparatus including: a processor; and a wireless transceiver coupled to the processor, wherein the processor is configured to transmit, via the wireless transceiver, assistance information related to an SL DRX configuration of a first UE, the assistance information being included in an SL UE Capability Information message of the first UE that is also transmitted to a second UE, or also included in a separate Radio Resource Control (RRC) message that is also transmitted to the second UE; and receive, via the wireless transceiver, the SL DRX configuration based on the assistance information transmitted to the second UE.

[0036] Yet another embodiment of the present disclosure provides an apparatus, the apparatus including: a processor; and a wireless transceiver coupled to the processor, wherein the processor is configured to receive, from a second apparatus via the wireless transceiver, assistance information related to an SL DRX configuration of a first UE, the assistance information being included in an SL UE Capability Information message of the first UE also received from the first UE or included in a separate Radio Resource Control (RRC) message also received from the first UE, and to transmit, via the wireless transceiver, the SL DRX configuration based on the assistance information received from the first UE.

[0037] To explain the manner in which the advantages and features of the present disclosure can be obtained, the present disclosure will be described with reference to specific embodiments that are illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the present disclosure and are not intended to limit the scope of the present disclosure. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 illustrates an exemplary communication system, in accordance with some embodiments of the present disclosure. [Figure 2] 1 is a flowchart of an exemplary sidelink unicast communication, in accordance with some embodiments of the present disclosure. [Figure 3] 10 is a flowchart of another exemplary sidelink unicast communication, in accordance with some embodiments of the present disclosure. [Figure 4A] 1 is a flowchart of an exemplary method performed by a receiving (Rx) UE for wireless communication, in accordance with some embodiments of the present disclosure. [Figure 4B] 1 is a flowchart of an exemplary method performed by a transmitting (Tx) UE for wireless communication, in accordance with certain embodiments of the present disclosure. [Figure 5] FIG. 1 is a simplified block diagram of an exemplary device, according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0039] The detailed description of the accompanying drawings is intended to be an illustration of preferred embodiments of the invention and is not intended to represent the only form in which the invention may be practiced. It is to be understood that the same or equivalent functions may be accomplished by different embodiments which are intended to be encompassed within the spirit and scope of the invention.

[0040] Reference will now be made in detail to several embodiments of the present application, examples of which are illustrated in the accompanying drawings. For ease of understanding, the embodiments are given under specific network architectures and new service scenarios, such as 3GPP 5G, 3GPP LTE Release 8, etc. With the development of network architectures and new service scenarios, it is contemplated that all embodiments in the present application are also applicable to similar technical problems, and furthermore, the terms described in the present application may change, which shall not affect the principle of the present application.

[0041] A UE under a new radio (NR) V2X scenario may be referred to as a V2X UE. A V2X UE that transmits data according to sidelink resources scheduled by a BS or selected by itself may be referred to as a transmitting UE, transmitting UE, transmitting V2X UE, Tx UE, V2X Tx UE, SL Tx UE, etc. A V2X UE that receives data according to sidelink resources scheduled by a BS or selected by a Tx UE may be referred to as a receiving UE, receiving UE, receiving V2X UE, Rx UE, V2X Rx UE, SL Rx UE, etc.

[0042] V2X UEs may include computing devices such as desktop computers, laptop computers, personal digital assistants (PDAs), tablet computers, smart televisions (e.g., Internet-connected televisions), set-top boxes, game consoles, security systems (including security cameras), in-vehicle computers, network devices (e.g., routers, switches, and modems), Internet of Things (IoT) devices, etc.

[0043] According to some embodiments of the present application, a V2X UE may include a portable wireless communication device, a smartphone, a mobile phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call receiver, or any other device capable of transmitting and receiving communication signals over a wireless network.

[0044] According to some embodiments of the present application, a V2X UE includes a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, etc. Moreover, a V2X UE may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or may be described using other terms used in the art. A V2X UE may communicate directly with a BS via an uplink (UL) communication signal.

[0045] A BS under an NR V2X scenario may be referred to as a base unit, base, access point, access terminal, macro cell, Node-B, enhanced Node B (eNB), gNB, Home Node-B, relay node, device, remote unit, or by any other terminology used in the art. BSs may be distributed over a geographic region. Generally, a BS is part of a radio access network, which may include one or more controllers communicatively coupled to one or more corresponding base stations.

[0046] A BS is typically communicatively coupled to one or more packet core networks (PCNs), which may be coupled to other networks such as a packet data network (PDN) (e.g., the Internet) and a public switched telephone network, among other networks. These and other elements of radio access and core networks are not shown but are generally well known by those skilled in the art. For example, one or more BSs may be communicatively coupled to a mobility management entity (MME), a serving gateway (SGW), and / or a packet data network gateway (PGW).

[0047] A BS may serve several V2X UEs in a serving area, e.g., a cell or cell sector, via wireless communication links. The BS may communicate directly with one or more V2X UEs via communication signals. For example, a BS may serve V2X UEs in a macrocell.

[0048] SL communication between Tx UE and Rx UE under NR V2X scenario includes groupcast communication, unicast communication, or broadcast communication.

[0049] Embodiments of the present application may be provided in network architectures that employ various service scenarios, such as, but not limited to, 3GPP 3G, LTE, LTE-Advanced (LTE-A), 3GPP 4G, 3GPP 5G NR, 3GPP LTE Release 12, and later. It is contemplated that the terminology described in the present application may change with the development of 3GPP and related communication technologies, which should not affect the principles of the present application.

[0050] FIG. 1 illustrates an exemplary communication system 100 in accordance with some embodiments of the present application.

[0051] As shown in Figure 1, communication system 100 includes a base station, e.g., BS 102, and several UEs, e.g., UE 101-A, UE 101-B, UE 101-C, and UE 101-D. According to some other embodiments of the present application, it is contemplated that the communication system may include more BSs and / or more or fewer UEs. Furthermore, it is contemplated that the names of the UEs (representing Tx UE, Rx UE, etc.) as illustrated and depicted in Figure 1 may vary. The UEs may communicate with each other via sidelinks.

[0052] Additionally, although each UE as shown in FIG. 1 is shown in the form of a smartphone, it is contemplated that the communication system may include any type of UE (e.g., a road map device, a mobile phone, a computer, a laptop, an Internet of Things (IoT) device, or other type of device) in accordance with some other embodiments of the present application.

[0053] According to some embodiments of the present disclosure, the UE 101-A may function as a Tx UE, and the UE 101-B and the UE 101-C may function as Rx UEs. The UE 101-A may exchange messages with the UE 101-B or the UE 101-C through a sidelink, for example, via a PC5 interface as defined in 3GPP TS 23.303. The UE 101-A may transmit information or data to other UEs in the communication system through SL unicast, SL groupcast, or SL broadcast. For example, the UE 101-A may transmit data to the UE 101-B in an SL unicast transmission session. The UE 101-A may transmit data to the UE 101-B and the UE 101-C in a groupcast group through an SL groupcast transmission session. The UE 101-A may also transmit data to the UE 101-B and the UE 101-C through an SL broadcast transmission session.

[0054] According to some other embodiments of the present disclosure, the UE 101-B may function as a Tx UE to transmit messages, and the UE 101-A may function as an Rx UE to receive messages from the UE 101-B.

[0055] Both UE 101-A and UE 101-B in the example shown in Figure 1 may transmit information or data to BS 102 and receive control information or data from BS 102, e.g., via the NR Uu interface. BS 102 may define one or more cells, and each cell may have a coverage area. As shown in Figure 1, both UE 101-A and UE 101-B are within the coverage area of ​​BS 102, and UE 101-C and UE 101-D are outside the coverage area of ​​BS 102.

[0056] 1 is not a specific base station, but may be any base station in the communication system. For example, if the communication system includes two BSs 102, the UE 101-A being within the coverage area of ​​any one of the two BSs 102 may be referred to as an instance where the UE 101-A is within the coverage area of ​​a BS 102 in the communication system. The UE 101-A being outside the coverage areas of both BSs 102 may be referred to as an instance where the UE 101-A is outside the coverage area of ​​a BS 102 in the communication system.

[0057] In some embodiments of the present disclosure, a Tx UE supports SL DRX and may perform SL unicast transmissions to an Rx UE that is an SL DRX-capable UE. In the SL unicast communication between the Tx UE and the Rx UE, there are two signaling exchanges for SL DRX configuration as follows: - signaling-1: signaling from Rx UE to Tx UE, which may be carried via PC5 RRC messages; and - signaling-2: Signaling from Tx UE to Rx UE, which may be carried via a message (eg, RRCReconfigurationSidelink) to deliver the SL DRX configuration.

[0058] When the Tx UE is within the coverage of the serving network and in the RRC connected state, the Tx UE may report the information received in signaling-1 (e.g., assistance information related to the SL DRX configuration) to the serving network, and then obtain the SL DRX configuration from dedicated RRC signaling from the serving network to generate signaling-2.

[0059] When a Tx UE is in an RRC idle state or an RRC inactive state, the Tx UE may obtain an SL DRX configuration based on a system information block (SIB) message received from the serving network. In an embodiment, the SIB message may include a set of SL DRX configurations, each corresponding to a respective quality of service (QoS) profile. The Tx UE may determine an SL DRX configuration from the set of SL DRX configurations based on assistance information received from the Rx UE. In another embodiment, the SIB message may include several common SL DRX configurations, and the Tx UE may determine an SL DRX configuration by itself from several common SL DRX configurations based on assistance information received from the Rx UE.

[0060] In some other embodiments, when a Tx UE is in an RRC idle state or an RRC inactive state and receives assistance information from an Rx UE, the Tx UE may request to enter an RRC connected state and transmit the received assistance information to the serving network to obtain an SL DRX configuration.

[0061] When the Tx UE is out of coverage, the Tx UE may obtain an SL DRX configuration based on pre-configuration. In an embodiment, a set of SL DRX configurations each corresponding to a respective QoS profile may be pre-configured in the UE. The Tx UE may determine an SL DRX configuration from the set of SL DRX configurations based on assistance information received from the Rx UE. In another embodiment, several common SL DRX configurations may be pre-configured in the UE, and the Tx UE may determine an SL DRX configuration by itself from several common SL DRX configurations based on assistance information received from the Rx UE.

[0062] When the Rx UE is in the coverage of the serving network and in the RRC connected state, the Rx UE may report the SL DRX configuration received in signaling-2 to the serving network.

[0063] 2 illustrates a flowchart of an exemplary sidelink unicast communication between a Tx UE and an Rx UE, both of which support SL DRX communication, in accordance with some embodiments of the present disclosure.

[0064] In step 201, the Rx UE transmits assistance information related to the SL DRX configuration to the Tx UE. In some embodiments of the present disclosure, the Rx UE may transmit the assistance information in response to a request for the assistance information from the Tx UE. In some other embodiments of the present disclosure, the Rx UE may transmit the assistance information to the Tx UE autonomously.

[0065] After receiving the assistance information, the Tx UE determines an SL DRX configuration based on the assistance information from the Rx UE, and the Tx UE sends the SL DRX configuration to the Rx UE in step 202. The SL DRX configuration may be included in an RRC reconfiguration message (e.g., RRCReconfigurationSidelink).

[0066] In step 203, the Rx UE sends a response to the Tx UE regarding whether the configurations in the RRC reconfiguration message are applicable. The response may include an RRC reconfiguration complete message (e.g., RRCReconfigurationCompletesidelink) indicating that the configurations in the RRC reconfiguration message are applied to the Rx UE. The response may also include an RRC reconfiguration failure message (e.g., RRCReconfigurationFailuresidelink), indicating that at least one configuration in the RRC reconfiguration message is not applicable.

[0067] 3 illustrates a flowchart of another exemplary sidelink unicast communication between a Tx UE and an Rx UE, both of which support SL DRX communication, in accordance with some embodiments of the present disclosure.

[0068] When a higher layer needs UE radio access capability information, after receiving an indication from that layer, the Tx UE may send a request (e.g., UECapabilityEnquirySidelink) to the Rx UE to request SL UE capability information of the Rx UE in step 301. The Rx UE may also send a request to the Tx UE to request SL capability information of the Tx UE. The timing for sending the request depends on the implementation of the Tx UE.

[0069] In step 302-a, the Rx UE may send its SL UE capability information to the Tx UE, for example, via UECapabilityInformationSidelink. In step 302-b, the Rx UE may send assistance information related to the SL DRX configuration to the Tx UE.

[0070] In some embodiments, the assistance information is included in the SL UE capability information transmitted from the Rx UE to the Tx UE. That is, step 302-a and step 302-b are included in the same step. The assistance information included in the SL UE capability information may be a request for an SL DRX configuration, and the request may include one or more bits. Additionally or alternatively, the assistance information included in the SL UE capability information may include an indication of one or more pre-defined SL DRX configurations proposed or preferred by the Rx UE, and the indication may include one or more indices of the one or more pre-defined SL DRX configurations.

[0071] In some other embodiments, the assistance information is sent separately from the SL UE capability information, i.e., they are sent in two separate messages. For example, the assistance information may be carried in a PC5 RRC message sent after UECapabilityInformationSidelink.

[0072] In an embodiment of the present disclosure, when the assistance information is transmitted separately from the SL UE capability information, the SL UE capability information may include an assistance information indicator, which indicates that the assistance information is transmitted separately. Upon receiving the assistance information indicator in the SL UE capability information, the Tx UE may know that the assistance information is transmitted from the Rx UE, and may postpone transmitting an RRC reconfiguration message to the Rx UE until it receives the assistance information from the Rx UE.

[0073] According to some embodiments of the present disclosure, the assistance information carried in signaling 1 from the Rx UE to the Tx UE, whether transmitted in the SL UE capability information or separately from the SL UE capability information, may include at least one of the following: - a request to obtain a SL DRX configuration from the Tx UE, this request may include one or more bits; - Uu DRX configuration of the Rx UE; - one or more DRX configurations for other links of the Rx UE, e.g., a SL DRX configuration for a unicast link between the Rx UE and another UE; - one or more SL DRX configurations or parameters proposed or preferred by the Rx UE, or - Accepting or rejecting the SL DRX configuration received from the Tx UE.

[0074] Since the status and traffic information of the Rx UE may change, the assistance information of the Rx UE may also change. Therefore, the assistance information of the Rx UE should be updated and sent to the Tx UE correspondingly, and the SL DRX configuration also needs to be adjusted according to the updated assistance information.

[0075] In some embodiments, the Rx UE periodically transmits the assistance information to the Tx UE.

[0076] In some other embodiments, when the Rx UE has one or more preferred SL DRX configurations or preferred DRX parameters, the Rx UE transmits assistance information to the Tx UE.

[0077] In some other embodiments, the Rx UE transmits the assistance information to the Tx UE when the assistance information is updated.

[0078] In some other embodiments, the Rx UE transmits assistance information to the Tx UE when the Rx UE performs a state transition (i.e., when the Rx UE's operating state changes), for example, between an RRC connected state and an RRC idle state or an RRC inactive state, or between in-coverage and out-of-coverage.

[0079] In some other embodiments, when the Rx UE receives a request for assistance information from the Tx UE, the Rx UE transmits the assistance information to the Tx UE. The request may include an indication of requesting assistance information related to SL DRX configurations from the Rx UE. The indication may include one or more bits. Additionally or alternatively, the request may include one or more SL DRX configurations proposed by the Tx UE. The timing for transmitting the request is up to the implementation of the TX UE.

[0080] After receiving the assistance information from the Rx UE, the Tx UE may determine an SL DRX configuration based on the assistance information. In step 303, the Tx UE may send the determined SL DRX configuration to the Rx UE. The SL DRX configuration may be included in an RRC reconfiguration message, such as RRCReconfigurationSidelink, sent from the Tx UE to the Rx UE.

[0081] In step 304, the Rx UE may send a response to the Tx UE regarding whether the SL DRX configuration received from the Tx UE is applicable.

[0082] In the present disclosure, an SL DRX configuration failure indication is introduced to indicate a failure to apply an SL DRX configuration on the Rx UE's side. Specifically, when the Rx UE rejects the SL DRX configuration received from the Tx UE or when the Rx UE is unable to apply the SL DRX configuration, the Rx UE may send an RRC reconfiguration failure message (e.g., RRCReconfigurationFailuresidelink) with an SL DRX configuration failure indication to the Tx UE. In some embodiments, the SL DRX configuration failure indication is included in the RRC reconfiguration failure message. In some other embodiments, the SL DRX configuration failure indication is included in a message sent together with the RRC reconfiguration failure message.

[0083] In an embodiment, the SL DRX configuration failure indication from the Rx UE may include the cause of the SL DRX configuration failure. In another embodiment, the Rx UE may send updated assistance information along with the SL DRX configuration failure indication to the Tx UE, so that the Tx UE may determine and send an updated SL DRX configuration based on the updated assistance information.

[0084] The RRC reconfiguration message containing the SL DRX configuration may further include one or more AS configurations. Regarding the application of the SL DRX configuration and one or more AS configurations in the Rx UE, there are four scenarios as described in Table 1 below.

[0085] [Table 1]

[0086] Scenario 1: Both the SL DRX configuration and one or more AS configurations received from the Tx UE are applicable to the Rx UE. In this case, the response of the Rx UE sent in step 304 is an RRC reconfiguration complete message (e.g., RRCReconfigurationCompletesidelink). The Rx UE applies both the received SL DRX configuration and the received one or more AS configurations.

[0087] Scenario 2: The received SL DRX configuration is not applicable to the Rx UE, but the received one or more AS configurations are applicable to the Rx UE. In this case, the Rx UE's response sent in step 304 is an RRC reconfiguration failure message (e.g., RRCReconfigurationFailuresidelink) with an SL DRX configuration failure indication. In this case, the Rx UE may adopt one of the following two options: Option 1: The Rx UE applies the received AS configuration(s) and does not apply the received SL DRX configuration. The Rx UE may continue to apply the previous SL DRX configuration until a new SL DRX configuration is received. In some embodiments, the new SL DRX configuration is included in a new RRC reconfiguration message. Option 2: The Rx UE does not apply the received AS configuration(s) or the received SL DRX configuration. The Rx UE may continue to apply the previous SL DRX configuration and the previous AS configuration(s) until a new RRC reconfiguration message is received.

[0088] Scenario 3: The received SL DRX configuration is applicable, but one or more received AS configurations are not applicable to the Rx UE. In this case, the Rx UE's response sent in step 304 is an RRC reconfiguration failure message (e.g., RRCReconfigurationFailuresidelink) without an SL DRX configuration failure indication. In this case, the Rx UE may adopt one of the following two options: Option 1: The Rx UE applies the received SL DRX configuration and does not apply the received AS configuration(s). The Rx UE may continue to apply the previous AS configuration(s) until a new AS configuration is received. In some embodiments, the new AS configuration is included in a new RRC reconfiguration message. Option 2: The Rx UE does not apply the received AS configuration(s) or the received SL DRX configuration. The Rx UE may continue to apply the previous SL DRX configuration and the previous AS configuration(s) until a new RRC reconfiguration message is received.

[0089] Scenario 4: Neither the received SL DRX configuration nor the received one or more AS configurations are applicable. In this case, the Rx UE's response sent in step 304 is an RRC reconfiguration failure message (e.g., RRCReconfigurationFailuresidelink) with an SL DRX configuration failure indication. In this case, the Rx UE may continue to apply the previous SL DRX configuration and the previous one or more AS configurations until a new RRC reconfiguration message is received.

[0090] In scenarios 2 and 4, after receiving the SL DRX configuration failure indication from the Rx UE, if the Tx UE is in the RRC connected state, the Tx UE may send a report to the serving BS in step 305. This report may use the same format as the Tx UE's report for reporting the assistance information received in signaling-1 to the serving BS. This report may include at least one of the following information: the SL DRX configuration failure indication, the failure cause received from the Rx UE, and / or the updated assistance information from the Rx UE.

[0091] In some other embodiments, no SL DRX configuration failure indication is introduced. When the Rx UE rejects any of the AS configuration and the SL DRX configuration from the Tx UE, or when the Rx UE is not able to apply any of the AS configuration and the SL DRX configuration, the Rx UE may send an RRC reconfiguration failure message (e.g., RRCReconfigurationFailuresidelink) to the Tx UE and continue to use the previous AS configuration(s) and the previous SL DRX configuration.

[0092] After receiving the RRC reconfiguration failure message, the Tx UE may reconfigure one or more AS configurations and the SL DRX configuration and send a new RRC configuration message to the Tx UE including the new one or more AS configurations and the new SL DRX configuration.

[0093] The state of the UE may change due to the movement of the UE. For example, the UE may perform one of the following state transitions: Case 1: RRC Connected state to RRC Idle state or RRC Inactive state, Case 2: From in-coverage to out-of-coverage, Case 3: From RRC Idle or RRC Inactive state to RRC Connected state, Case 4: Out of coverage to in coverage, Case 5: RRC idle state to RRC inactive state, and Case 6: RRC Inactive State to RRC Idle State.

[0094] When a Tx UE or an Rx UE performs one of the state transitions, the SL DRX configuration may need to be updated.

[0095] When the Tx UE performs a state transition, the Tx UE obtains a new SL DRX configuration in the new state, determines a new SL DRX configuration, and sends the new SL DRX configuration to the Rx UE.

[0096] On the Rx UE side, before receiving the new SL DRX configuration, the Rx UE applies the SL DRX configuration provided in the old state. After receiving the new SL DRX configuration in the new state, the Rx UE applies the new SL DRX configuration if the new SL DRX configuration is applicable. If the new SL DRX configuration is not applicable, the Rx UE continues to apply the SL DRX configuration provided in the old state and may send a response to the Tx UE in a manner similar to that described with respect to step 304, and the Tx UE may determine an updated SL DRX configuration based on the response of the Rx UE.

[0097] According to some embodiments, when a Tx UE enters a new state, it may acquire a new SL DRX configuration in the new state and determine and send the new SL DRX configuration to the Rx UE without receiving assistance information from the Rx UE.

[0098] According to some other embodiments, when the Tx UE enters a new state, it may send an indication to the Rx UE to request assistance information, then determine a new SL DRX configuration in the new state based on the assistance information received from the Rx UE, and send the new SL DRX configuration to the Rx UE.

[0099] When the Rx UE performs a state transition, the Rx UE determines updated assistance information for the new state and transmits the updated assistance information to the Tx UE. In some embodiments, the updated assistance information may indicate the state transition of the Rx UE.

[0100] FIG. 4A illustrates a flowchart of an exemplary method performed by an Rx UE for wireless communication, in accordance with certain embodiments of the present disclosure.

[0101] In step 401, the Rx UE sends assistance information related to the Rx UE's SL DRX configuration to the Tx UE. The assistance information may be sent in an SL UE Capability Information message (e.g., UECapabilityInformationSidelink) indicating the Rx UE's SL UE capabilities, or may be sent in a separate RRC message sent separately from the SL UE Capability Information message.

[0102] In step 403, the Rx UE receives the SL DRX configuration based on the assistance information from the Tx UE sent to the Tx UE.

[0103] Support information is available at - requirements for SL DRX configuration, - Uu DRX configuration of the Rx UE; - one or more DRX configurations for one or more other links of the Rx UE; - one or more SL DRX configurations preferred or proposed by the Rx UE, or - Accepting or rejecting the SL DRX configuration received from the Tx UE It includes at least one of the following:

[0104] In some embodiments, the assistance information is transmitted periodically. In some other embodiments, the assistance information is transmitted when the Rx UE has one or more preferred SL DRX configurations, when the Rx UE's assistance information is updated, when the Rx UE's operating state changes, or when the Rx UE receives a request for assistance information from the Tx UE.

[0105] In some embodiments, the request for assistance information includes a one-bit indication or list of DRX configurations proposed or preferred by the Tx UE.

[0106] In some embodiments, the assistance information included in the Rx UE's SL UE Capability Information message includes a one-bit request for a SL DRX configuration or an index of the SL DRX configuration proposed by the Rx UE.

[0107] In some embodiments, the SL UE Capability Information message includes an Assistance Information indicator that indicates that the assistance information should be sent in a separate RRC message.

[0108] After receiving the SL DRX configuration from the Tx UE, which is transmitted together with or separately from the one or more AS configurations, the Rx UE determines whether the SL DRX configuration and the one or more AS configurations are applicable, and performs different operations based on the determined result, as follows:

[0109] If the SL DRX configuration is not applicable and one or more AS configurations received along with the SL DRX configuration are applicable (i.e., scenario 2 in Table 1), the Rx UE sends an RRC reconfiguration failure message with an SL DRX configuration failure indication to the Tx UE. The SL DRX configuration failure indication may include the SL DRX configuration failure cause.

[0110] The Rx UE may then apply the previous SL DRX configuration until a new RRC reconfiguration message is received, apply the one or more AS configurations until a new RRC reconfiguration message is received, or continue to apply the previous one or more AS configurations. The Rx UE may receive an updated SL DRX configuration from the Tx UE in response to the SL DRX configuration failure indication.

[0111] If the SL DRX configuration is applicable and one or more AS configurations received along with the SL DRX configuration are not applicable (i.e., scenario 3 in Table 1), the Rx UE sends an RRC reconfiguration failure message without an SL DRX configuration failure indication to the Tx UE.

[0112] The Rx UE may then apply the previous AS configuration or configurations until a new RRC reconfiguration message is received, apply the SL DRX configuration until a new RRC reconfiguration message is received, or continue to apply the previous SL DRX configuration.

[0113] If the SL DRX configuration is not applicable and one or more AS configurations received along with the SL DRX configuration are not applicable (i.e., scenario 4 in Table 1), the Rx UE sends an RRC reconfiguration failure message with an SL DRX configuration failure indication to the Tx UE and continues to apply the previous SL DRX configuration and the previous one or more AS configurations until a new RRC reconfiguration message is received. The SL DRX configuration failure indication may include the SL DRX configuration failure cause. The Rx UE may receive an updated SL DRX configuration from the Tx UE in response to the SL DRX configuration failure indication.

[0114] If the SL DRX configuration is applicable and one or more AS configurations received along with the SL DRX configuration are applicable (i.e., scenario 1 in Table 1), the Rx sends an RRC reconfiguration complete message to the Tx UE and applies both the SL DRX configuration and the one or more AS configurations.

[0115] In some embodiments, the Rx UE may send updated assistance information to the Tx UE if the SL DRX configuration is not applicable.

[0116] FIG. 4B illustrates a flowchart of an exemplary method performed by a Tx UE for wireless communication, in accordance with some embodiments of the present disclosure, which corresponds to the method illustrated in FIG. 4A.

[0117] In step 402, the Tx UE receives, from the Rx UE, assistance information related to the Rx UE's SL DRX configuration. The assistance information may be received in an SL UE Capability Information message (e.g., UECapabilityInformationSidelink) indicating the Rx UE's SL UE capabilities, or may be received in a separate RRC message sent separately from the SL UE Capability Information message.

[0118] In step 404, the Tx UE sends a SL DRX configuration to the Rx UE based on the assistance information received from the Rx UE.

[0119] Support information is available at - requirements for SL DRX configuration, - Uu DRX configuration of the Rx UE; - one or more DRX configurations for one or more other links of the Rx UE; - one or more SL DRX configurations preferred or proposed by the Rx UE, or - Accepting or rejecting the SL DRX configuration received from the Tx UE It includes at least one of the following:

[0120] In some embodiments, the assistance information is received periodically.

[0121] In some embodiments, the Tx UE may send a request for assistance information to the Rx UE, the request for assistance information including a one-bit indication or list of DRX configurations proposed or preferred by the Tx UE.

[0122] In some embodiments, the assistance information included in the Rx UE's SL UE Capability Information message includes a one-bit request for a SL DRX configuration or an index of the SL DRX configuration proposed by the Rx UE.

[0123] In some embodiments, the SL UE Capability Information message includes an Assistance Information indicator that indicates that the assistance information should be received in a separate RRC message.

[0124] In some embodiments, the Tx UE receives an SL DRX configuration failure indication from the Rx UE and sends an updated SL DRX configuration to the Rx UE in response to the SL DRX configuration failure indication.

[0125] In some embodiments, the Tx UE may transmit to the BS at least one of updated assistance information from the Rx UE, an SL DRX configuration failure indication, or an SL DRX configuration failure cause. The SL DRX configuration failure indication received from the Rx UE may include the SL DRX configuration failure cause.

[0126] When the operating state of the Tx UE changes, the Tx UE may send a request for assistance information to the Rx UE. The Tx UE may obtain an updated SL DRX configuration when its state changes, and may send the updated SL DRX configuration to the Rx UE when the updated SL DRX configuration is obtained.

[0127] In some embodiments, the Tx UE may transmit the assistance information received from the Rx UE to the BS to request a SL DRX configuration and may receive the SL DRX configuration from the BS.

[0128] In some embodiments, the Tx UE may determine an SL DRX configuration from a set of SL DRX configurations each corresponding to a respective QoS profile or from a set of common SL DRX configurations. For example, when the Tx UE is in an RRC idle state or an RRC inactive state, the Tx UE may determine an SL DRX configuration from the set of common SL DRX configurations. The set of SL DRX configurations or the set of common SL DRX configurations is pre-configured in the Tx UE or received in a SIB message.

[0129] In some embodiments, upon receiving assistance information from the Rx UE, if the Tx UE is in an RRC idle state or an RRC inactive state, the Tx UE may request to enter an RRC connected state.

[0130] 5 illustrates a simplified block diagram of an exemplary apparatus 500 according to some embodiments of the present application. The apparatus 500 may be at least part of or may include a UE (e.g., UE 101-A, UE 101-B, UE 101-C, or UE 101-D as shown in FIG. 1, or a Tx UE or Rx UE as shown in FIG. 2 or FIG. 3) or other device with similar functionality.

[0131] 5, the apparatus 500 may include a receiver 501, a transmitter 503, a processor 505, and a non-transitory computer-readable medium 507. The non-transitory computer-readable medium 507 stores computer-executable instructions. The processor 505 is configured to be coupled to the non-transitory computer-readable medium 507, the receiver 501, and the transmitter 503. In some other embodiments of the present application, it may be contemplated that the apparatus 500 may include more computer-readable media, receivers, transmitters, and processors according to actual requirements. In some embodiments of the present application, the receiver 501 and the transmitter 503 may be a wireless receiver and a wireless transmitter, respectively, or may be integrated into a single device such as a wireless transceiver. In some embodiments, the apparatus 500 may further include an input device, a memory, and / or other components.

[0132] In some embodiments of the present application, the non-transitory computer-readable medium 507 may store computer-executable instructions to cause the processor 505 to perform a method performed by a Tx UE or an Rx UE according to any embodiment of the present application, e.g., the method shown in FIG. 2, FIG. 3, FIG. 4A, or FIG. 4B.

[0133] For example, processor 505 may be configured to transmit, via transmitter 503, assistance information related to the SL DRX configuration, where the assistance information is transmitted in an SL UE Capability Information message indicating the SL UE capabilities of apparatus 500 or transmitted separately from the SL UE Capability Information message. Processor 505 may further be configured to receive, via receiver 501, the SL DRX configuration determined based on the assistance information.

[0134] For example, processor 505 may be configured to receive, from the second device via receiver 501, assistance information related to the SL DRX configuration, where the assistance information is received in an SL UE Capability Information message indicating the SL UE capabilities of the second device or is received separately from the SL UE Capability Information message. Processor 505 may be further configured to transmit, via transmitter 503, the SL DRX configuration determined based on the assistance information.

[0135] The methods of the present disclosure may be performed on a programmed processor. However, the controllers, flowcharts, and modules may also be implemented in hardware electronic or logical circuits such as general-purpose or special-purpose computers, programmed microprocessors or microcontrollers and peripheral integrated circuit elements, integrated circuits, discrete element circuits, programmable logic devices, etc. In general, any device having a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processing functions of the present disclosure.

[0136] While the present disclosure has been described with reference to specific embodiments thereof, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in other embodiments. Also, not all elements shown in the figures are necessarily required for the operation of the disclosed embodiments. For example, one skilled in the art of the disclosed embodiments will be able to implement and use the teachings of the present disclosure by simply utilizing the elements of the independent claims. Accordingly, the embodiments of the present disclosure described herein are intended to be illustrative, not limiting. Various changes can be made without departing from the spirit and scope of the present disclosure.

[0137] In this disclosure, relational terms such as "first," "second," and the like may be used solely to distinguish one entity or act from another, without necessarily requiring or implying an actual relationship or order between the entities or acts. The terms "comprise," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements not only includes those elements, but may also include other elements not expressly listed or inherent in such process, method, article, or apparatus. An element preceded by "a," "an," etc., does not, without further constraints, preclude the presence of additional identical elements in a process, method, article, or apparatus that includes that element. Additionally, the term "another" is defined as at least a second or more. Terms such as "comprising," "having," and the like are defined herein as "comprising." [Explanation of symbols]

[0138] 100 Communication Systems 101 User Equipment (UE) 102 Base station (BS) 501 Receiver 503 Transmitter 505 processor 507 Non-transitory computer-readable medium

Claims

1. 1. A method performed by a first user equipment (UE), comprising: sending, to a second UE, assistance information related to a side link (SL) discontinuous reception (DRX) configuration of the first UE; The assistance information is included in a SL UE Capability Information message of the first UE that is also sent to the second UE; or also included in a separate Radio Resource Control (RRC) message sent to the second UE; receiving from the second UE a SL DRX configuration to be used based on the assistance information sent to the second UE; If the SL DRX configuration is not applicable and one or more Access Stratum (AS) configurations received together with the SL DRX configuration are applicable, sending an RRC reconfiguration failure message with an SL DRX configuration failure indication or a rejection indication to the second UE; applying a previous SL DRX configuration until a new RRC reconfiguration message is received; applying the one or more AS configurations or continuing to apply the previous one or more AS configurations until a new RRC reconfiguration message is received. method.

2. The support information is a requirement for the SL DRX configuration; a Uu DRX configuration of the first UE; one or more DRX configurations for one or more other links of the first UE; one or more desired SL DRX configurations by the first UE; or Accepting or rejecting the SL DRX configuration received from the second UE. The method of claim 1 , comprising at least one of:

3. The support information is If the first UE has one or more preferred SL DRX configurations, When the support information of the first UE is updated or changed, When the operating state of the first UE changes, or When the first UE receives a request for the assistance information from the second UE. The method of claim 1 , wherein the signal is transmitted in at least one of:

4. 2. The method of claim 1, wherein the assistance information included in the SL UE Capability Information message of the first UE comprises a one-bit request for the SL DRX configuration or an index of an SL DRX configuration proposed by the first UE.

5. The method of claim 1 , wherein the SL UE Capability Information message of the first UE comprises an assistance information indicator indicating that the assistance information should be transmitted in the separate RRC message.

6. If the SL DRX configuration is applicable and one or more AS configurations received along with the SL DRX configuration are not applicable, sending an RRC reconfiguration failure message to the second UE without an SL DRX configuration failure indication or a rejection indication; applying the previous one or more AS configurations until a new RRC reconfiguration message is received; applying the SL DRX configuration or continuing to use the previous SL DRX configuration until a new RRC reconfiguration message is received; The method of claim 1 further comprising:

7. If the SL DRX configuration is not applicable and one or more AS configurations received together with the SL DRX configuration are not applicable, sending an RRC reconfiguration failure message with an SL DRX configuration failure indication or a rejection indication to the second UE; continuing to use the previous SL DRX configuration and the previous one or more AS configurations until a new RRC reconfiguration message is received; The method of claim 1 further comprising:

8. If the SL DRX configuration is applicable or accepted and one or more AS configurations received together with the SL DRX configuration are applicable or accepted, sending an RRC reconfiguration complete message to the second UE; applying both the SL DRX configuration and the one or more AS configurations; The method of claim 1 further comprising:

9. A method performed by a second user equipment (UE), comprising: receiving, from a first UE, assistance information related to sidelink (SL) discontinuous reception (DRX) of the first UE, the assistance information being included in a SL UE Capability Information message of the first UE also received from the first UE or included in a separate Radio Resource Control (RRC) message also received from the first UE; determining a SL DRX configuration based on the assistance information received from the first UE; transmitting to the first UE the SL DRX configuration to be used by the first UE; If the SL DRX configuration is not applicable and one or more Access Stratum (AS) configurations received together with the SL DRX configuration are applicable, receiving an RRC reconfiguration failure message with a SL DRX configuration failure indication or a rejection indication from the first UE; sending a new RRC reconfiguration message for the first UE to apply a previous SL DRX configuration; and transmitting a new RRC reconfiguration message to cause the first UE to apply the one or more AS configurations or to terminate the first UE continuing to apply a previous one or more AS configurations. method.

10. To the base station (BS), updated assistance information from the first UE; the SL DRX configuration failure indication; or Cause of SL DRX configuration failure The method of claim 9 , further comprising transmitting at least one of:

11. 10. The method of claim 9, further comprising the step of: sending a request for the assistance information to the first UE, wherein the request for the assistance information is sent when an operating state of the second UE changes.

12. obtaining an updated SL DRX configuration when an operating state of the second UE changes; 10. The method of claim 9, further comprising: when the updated SL DRX configuration is obtained, transmitting the updated SL DRX configuration to the first UE.

13. a processor; a wireless transceiver coupled to the processor, the processor comprising: transmitting, via the wireless transceiver, assistance information related to a sidelink (SL) discontinuous reception (DRX) configuration of a first UE, the assistance information being included in an SL UE Capability Information message of the first UE also transmitted to a second UE, or included in a separate Radio Resource Control (RRC) message also transmitted to the second UE; receiving, via the wireless transceiver, an SL DRX configuration based on the assistance information transmitted to the second UE; If the SL DRX configuration is not applicable and one or more Access Stratum (AS) configurations received together with the SL DRX configuration are applicable, sending an RRC reconfiguration failure message with an SL DRX configuration failure indication or a rejection indication to the second UE; Apply the previous SL DRX configuration until a new RRC reconfiguration message is received, Applying the one or more AS configurations or continuing to apply the previous one or more AS configurations until a new RRC reconfiguration message is received. The apparatus is configured to:

14. a processor; a wireless transceiver coupled to the processor, the processor comprising: receiving, from a second device via the wireless transceiver, assistance information related to a sidelink (SL) discontinuous reception (DRX) configuration of a first UE, the assistance information being included in a SL UE Capability Information message of the first UE also received from the first UE or included in a separate Radio Resource Control (RRC) message also received from the first UE; transmitting, via the wireless transceiver, a SL DRX configuration based on the assistance information received from the first UE; If the SL DRX configuration is not applicable and one or more Access Stratum (AS) configurations received together with the SL DRX configuration are applicable, receiving an RRC reconfiguration failure message with an SL DRX configuration failure indication or a rejection indication from the first UE; sending a new RRC reconfiguration message for the first UE to apply a previous SL DRX configuration; Sending a new RRC reconfiguration message to terminate the first UE's application of the one or more AS configurations or to cause the first UE to continue applying a previous one or more AS configurations. The apparatus is configured to:

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