Method and apparatus for managing sidelink transmissions

Abstract

The present disclosure relates to methods and apparatus for configuring discontinuous reception for sidelink transmissions between communication terminals in a wireless communication network. In one implementation, the method can include receiving first discontinuous reception (DRX) configuration information from a wireless network access node, receiving second DRX configuration information from a second user equipment. The method can further include obtaining a DRX configuration scheme for sidelink communications between the first user equipment and second user equipment based on the first DRX configuration information and the second DRX configuration information.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to wireless communications and, more specifically, to managing sidelink transmissions between communication terminals including vehicles. BACKGROUND

[0002] Sidelink is a kind of one-sided wireless communication service, i.e., communication between communication terminals. Vehicle networking refers to a large-scale system for wireless communication and information exchange among vehicles, pedestrians, roadside devices, and the Internet in accordance with agreed communication protocols and data exchange standards. Vehicle networking communication enables vehicles to increase driving safety, improve traffic efficiency, and obtain convenient or entertainment information. Vehicle networking communication can be divided into three types according to the object of wireless communication: communication between vehicles (i.e., vehicle-to-vehicle (V2V)); communication between vehicles and roadside devices / network infrastructure (i.e., vehicle-to-infrastructure / vehicle-to-network (V2I / V2N)); and communication between vehicles and pedestrians (i.e., vehicle-to-pedestrian (V2P)). These types of communication are collectively referred to as vehicle-to-everything (V2X) communication.

[0003] In the study of V2X communication in the Third Generation Partnership Project (3GPP), the sidelink-based V2X communication method between user equipment is one of the ways to implement V2X standards, in which traffic data is sent directly from the source user equipment to the destination user equipment via the air interface without being forwarded by the base station and the core network, as shown in Figure 1 Such V2X communication is referred to as PC5-based V2X communication or V2X sidelink communication.

[0004] With the advancement and development of the automation industry, the scenarios for V2X communication are further diversified, and the requirements for performance are also increasingly high. Advanced V2X services include vehicle platooning, extended sensors, advanced driving (semi-automatic driving and full-automatic driving), and remote driving. The expected performance requirements can include: supporting data packets of 50 bytes to 12000 bytes in size, a transmission rate of 2 to 50 messages per second, a maximum end-to-end delay of 3 milliseconds to 500 milliseconds, a reliability of 90% to 99.999%, a data rate of 0.5 Mbps to 1000 Mbps, and a transmission range of 50 meters to 1000 meters. SUMMARY

[0005] The present disclosure relates to methods, systems, and devices related to wireless communications, and more specifically to configuring discontinuous reception for sidelink transmissions between communication terminals.

[0006] In one embodiment, a method performed by a first user equipment in a wireless communication network is disclosed. The method can include receiving first discontinuous reception configuration information from a wireless network access node and receiving second discontinuous reception configuration information from a second user equipment. The method can further include obtaining a discontinuous reception configuration scheme for sidelink communication between the first user equipment and the second user equipment based on the first discontinuous reception configuration information and the second discontinuous reception configuration information.

[0007] In one embodiment, a method performed by a first user equipment in a wireless communication network is disclosed. The method can include receiving discontinuous reception configuration information from a wireless network access node or a second user equipment. The method can further include obtaining a discontinuous reception configuration scheme for sidelink communication between the first user equipment and the second user equipment based on the DRX configuration information.

[0008] In one embodiment, a method performed by a second user equipment in a wireless communication network is disclosed. The method can include sending second DRX configuration information to a first user equipment, which can help the first user equipment determine a DRX configuration scheme for sidelink communication between the first user equipment and the second user equipment based on the second DRX configuration information and first DRX configuration information received from a wireless network access node.

[0009] In another embodiment, an apparatus for wireless communication can include a memory that stores instructions and a processing circuitry in communication with the memory. When the processing circuitry executes the instructions, the processing circuitry is configured to perform the above method.

[0010] In another embodiment, a computer-readable medium includes instructions that, when executed by a computer, cause the computer to perform the above method.

[0011] The above and other aspects and implementations thereof are more fully described in the following detailed description together with the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 An example diagram of a wireless communication network is shown in accordance with various embodiments.

[0013] Figure 2 A flowchart of a method for configuring discontinuous reception for sidelink transmission is shown in accordance with an embodiment.

[0014] Figure 3 A flowchart of a method for configuring discontinuous reception for sidelink transmission is shown in accordance with an embodiment.

[0015] Figure 4A flow diagram illustrating a method for configuring discontinuous reception for sidelink transmissions according to embodiments is shown. DETAILED DESCRIPTION

[0016] The techniques and examples of implementations and / or embodiments in this disclosure can be used to improve performance in wireless communication systems. The term“exemplary” is used to mean“an example of’ and, unless otherwise stated, does not imply that a particular example, implementation or embodiment is preferred or ideal. The section headings used in this disclosure are for the convenience of the reader only and are not to be construed as limiting any of the technology disclosed in any particular section. It is noted that these implementations can be embodied in various forms and, therefore, should not be limited to any specific form implied in the foregoing description. It is further noted that implementations can be embodied as a method, an apparatus, a component, or a system. Accordingly, embodiments of this disclosure can be embodied in hardware, software, firmware, or any combination thereof.

[0017] A wireless access network provides network connectivity between user equipment (UE) and information or data networks, such as text, voice or video communication networks, the Internet, etc. An example wireless access network can be cellular technology based, which can be further based on, for example, 4G LTE or 5G NR technology and / or formats. Figure 1 An example system diagram of a wireless communication network 100 including UEs 102, 124, and 126 and wireless access network nodes (WANNs) 104 according to various embodiments is shown. The UEs 102, 124, and 126 can include, but are not limited to, mobile phones, smart phones, tablet computers, laptop computers, vehicle-mounted communication devices, roadside communication devices, smart electronic devices or appliances (including air conditioners, televisions, refrigerators, ovens), or other devices capable of communicating wirelessly over a network. The UEs can communicate directly with each other via sidelink. Taking UE 102 as an example, it can include a transceiver circuitry 106 coupled to an antenna 108 to enable wireless communication with the wireless access network nodes 104 and UEs 124 / 126. The transceiver circuitry 106 can also be coupled to a processor 110, which can also be coupled to a memory 112 or other storage device. The memory 112 can store instructions or code therein that, when read and executed by the processor 110, cause the processor 110 to implement the various methods described herein.

[0018] Similarly, the WANN 104 can comprise a base station or other wireless network access point capable of wirelessly communicating with one or more UEs over a network. The WANN 104 can comprise a 4G LTE base station, a 5G NR base station, a 5G central unit base station, or a 5G distributed unit base station. The WANN 104 can be configured to perform a corresponding set of wireless network functions. The set of wireless network functions can not be the same between different types of wireless access network nodes. However, the set of wireless network functions can overlap functionally between different types of wireless access network nodes. The WANN 104 can comprise transceiver circuitry 114 coupled to an antenna 116, which can include an antenna tower 118 in various ways, to enable wireless communication with the UEs 102, 124, or 126. The transceiver circuitry 114 can also be coupled to one or more processors 120, which can also be coupled to a memory 122 or other storage device. The memory 122 can store instructions or code therein that, when read and executed by the processor 120, cause the processor 120 to implement the various methods described herein.

[0019] For simplicity and clarity, only one WANN and three UEs are shown in the wireless communication network 100. It will be understood that there can be multiple WANNs in the wireless communication network 100, and each WANN can simultaneously serve one or more UEs. In addition to UEs and WANNs, the network 100 can further include any other network nodes having different functions, such as network nodes in a core network of the wireless communication network 100. Moreover, while various embodiments will be discussed in the context of the particular example wireless communication network 100, the underlying principles are applicable to other applicable wireless communication networks.

[0020] In sidelink communication such as V2X communication between UEs, the UEs need to frequently monitor the sidelink transmission resource pool of the UEs, for example, by sensing, in order to obtain sidelink transmission resources from the sidelink transmission resource pool, which incurs huge power consumption and inefficiency. One of the purposes of the present disclosure is to reduce the power consumption of the UEs in sidelink transmission. For example, the UEs can be configured with discontinuous reception (DRX). Discontinuous reception is a method used in wireless communication to save user equipment battery. The user equipment and the network can negotiate the phases in which data transfer occurs. During other times, the user equipment can turn off its receiver and enter a low-power state. In this way, the power consumption of the user equipment can be saved.

[0021] Figure 2 An example implementation 200 for configuring sidelink DRX for sidelink transmission of a user equipment is shown. By way of example, reference will be made to Figure 1 and Figure 2Various operations of a first user equipment, such as UE 102, are described that configure sidelink DRX for a sidelink communication link between UE 102 and a second user equipment, such as UE 124. Herein, for the purpose of explaining the present disclosure, UE 102 can be used as a sidelink receiving user equipment and UE 124 can be used as a sidelink transmitting user equipment.

[0022] UE 102 can receive first DRX configuration information from a wireless network access node, such as WAN 118 (210). For example, UE 102 can receive the first DRX configuration information via a radio resource control (RRC) dedicated message or a broadcast message. The first DRX configuration information can be configured by WAN 118. In an implementation, the first DRX configuration information can include a subset of DRX configuration parameters required to configure sidelink DRX. For example, the first DRX configuration information can include DRX configuration parameters drx-LongCycleStartOffset, drx-LongCycle, and drx-StartOffset. In another implementation, the first DRX configuration information can include a complete set of DRX configuration parameters required to configure sidelink DRX. The values of the DRX configuration parameters in the first DRX configuration information can serve as default values for the DRX configuration parameters when configuring sidelink DRX. Additionally or alternatively, the first DRX configuration information received from WAN 118 can also be used to configure sidelink DRX for sidelink communications between UE 102 and other UEs, such as UE 126.

[0023] UE 102 can receive second DRX configuration information from a second user equipment, such as UE 124 (220). For example, UE 102 can receive the second DRX configuration information via a PC5 RRC dedicated message or a broadcast message. The second DRX configuration information can be configured by UE 124. Similar to the first DRX configuration information, the second DRX configuration information can include a subset of a complete set of DRX configuration parameters for configuring sidelink DRX. The second DRX configuration information can include, for example, a duration, an on-duration time pattern, a first inactivity timer, and a second inactivity timer. The on-duration time pattern can include a bitmap of slots indicating sidelink DRX on-duration. In an implementation, the first DRX configuration information and the second DRX configuration information can include overlapping DRX configuration parameters, but the overlapping DRX configuration parameters can be assigned different values in the first DRX configuration information and the second DRX configuration information. Alternatively, there are no overlapping DRX configuration parameters in the first DRX configuration information and the second DRX configuration information.

[0024] Subsequently, the UE 102 can obtain a DRX configuration scheme for sidelink communication between the UE 102 and the UE 124 based on the first DRX configuration information and the second DRX configuration information (230). The DRX configuration scheme can include a plurality of DRX configuration parameters. For example, the DRX configuration scheme can be defined with a data structure as follows:

[0025]

[0026]

[0027]

[0028] In one implementation, the UE 102 can combine the DRX configuration parameters in the first DRX configuration information and the DRX configuration parameters in the second DRX configuration information into the DRX configuration scheme. For example, the UE 102 can assign the values of the DRX configuration parameters in the second DRX configuration information to the corresponding DRX configuration parameters in the DRX configuration scheme. In the case that the second DRX configuration information does not include a DRX configuration parameter corresponding to a particular DRX configuration parameter in the DRX configuration scheme, the UE 102 can search for a DRX configuration parameter corresponding to the particular DRX configuration in the first DRX configuration information, and then assign the value of the corresponding DRX configuration parameter in the first DRX configuration information to the particular DRX configuration parameter.

[0029] If a DRX configuration parameter in the DRX configuration scheme is not included in the second DRX configuration information, the UE 102 can assign the value of the same DRX configuration parameter in the first DRX configuration information to the DRX configuration parameter in the DRX configuration scheme. That is, the value of the DRX configuration parameter in the first DRX configuration information serves as a default value for the corresponding DRX configuration parameter in the DRX configuration scheme.

[0030] In another implementation, in the case that the UE 102 fails to receive the second DRX configuration information from the UE 124, the UE 102 can obtain a DRX configuration scheme for sidelink communication between the UE 102 and the UE 104 based on the first DRX configuration information received from the WANN 118. For example, the UE 102 can simply use the first DRX configuration information received from the WANN 118 as the DRX configuration scheme. Similarly, in the case that the UE 102 fails to receive the first DRX configuration information from the WANN 118, the UE 102 can obtain a DRX configuration scheme for sidelink communication between the UE 102 and the UE 124 based on the second DRX configuration information received from the UE 124. For example, the UE 102 can simply use the second DRX configuration information received from the UE 124 as the DRX configuration scheme.

[0031] In further implementations, such as Figure 3 As shown, UE 102 may receive DRX configuration information from either WANN 118 or UE 124 (310). In this case, UE 102 may obtain a DRX configuration scheme for side-to-side communication between UE 102 and UE 124 based on the received DRX configuration information (320).

[0032] Once the sideline DRX configuration scheme is set, UE 102 does not need to continuously monitor the Physical Sideline Control Channel (PSCCH). Instead, the UE can monitor the PSCCH only during the receive-on duration, which can help reduce the UE's power consumption.

[0033] Optionally, UE 102 can configure sideline DRX for sideline communication between UE 102 and UE 124 by considering DRX configuration information received from a third user equipment (such as UE 126). In one implementation, UE 102 can receive third DRX configuration information from a third user equipment (such as UE 126). UE 102 can then determine a DRX configuration scheme based on the first, second, and third DRX configuration information. For example, UE 102 can assign the values ​​of DRX configuration parameters in the second DRX configuration information to the corresponding DRX configuration parameters in the DRX configuration scheme. If the second DRX configuration information does not include DRX configuration parameters corresponding to a specific DRX configuration parameter in the DRX configuration scheme, UE 102 can search for a DRX configuration parameter corresponding to the specific DRX configuration parameter in the first and third DRX configuration information, and then assign the value of the corresponding DRX configuration parameter in the first DRX configuration information to the specific DRX configuration parameter. For example, UE 102 can first search for the corresponding DRX configuration parameter in the third DRX configuration information. If UE 102 fails to find the corresponding DRX configuration parameter in the third DRX configuration information, UE 102 can search for the corresponding DRX configuration parameter in the first DRX configuration information.

[0034] Optionally, before receiving the second DRX configuration information, UE 102 may send the first DRX configuration information to UE 124. UE 124 may configure the second DRX configuration information based on the first DRX configuration information.

[0035] Optionally, prior to receiving the first DRX configuration information, the UE 102 can transmit sidelink information of the UE 102 to the WANN 118. The sidelink information can include quality of service (QoS) information, destination identification information, and sidelink configuration assistance information such as traffic pattern information. In this way, the WANN 118 can configure the first DRX configuration information based on the sidelink information from the UE 102.

[0036] Optionally, the UE 102 can configure a sidelink DRX inactivity timer (DRX-InactivityTimer) for the sidelink communication link between the UE 102 and the UE 124. While the sidelink DRX inactivity timer is running, the UE 102 can determine that DRX is not being used for the sidelink communication link and thus perform sidelink communications without DRX. Upon receiving an indication to enable DRX for the sidelink communication link, the UE 102 can stop the sidelink DRX inactivity timer. For example, the UE 102 can stop the sidelink DRX inactivity timer upon receiving a sidelink DRX command medium access control (MAC) control element (CE) for the sidelink communication link.

[0037] Optionally, the WANN 118 can configure whether the UE 102 is allowed to report sidelink DRX preferences for the sidelink communication link between the UE 102 and the UE 124 to the WANN 118 or the UE 124. Upon receiving an indication from the WANN 118 to allow the UE 102 to report sidelink DRX preferences to the WANN 118, the UE 102 can transmit, for example, assistance information including sidelink DRX preferences for the sidelink communication link to the WANN 118. By way of example, a data structure for sidelink DRX preferences is shown below. As indicated, the sidelink DRX preferences can include, for example, a preferred DRX inactivity timer, a preferred DRX long cycle, a preferred DRX short cycle, and a preferred DRX short cycle timer.

[0038]

[0039]

[0040] Similarly, upon receiving an indication from the WANN 118 to allow the UE 102 to report sidelink DRX preferences to the UE 124, the UE 102 can transmit, for example, assistance information including sidelink DRX preferences for the sidelink communication link to the UE 124. Additionally or alternatively, the WANN 118 can configure whether the UE 124 is allowed to receive sidelink DRX preferences from the UE 102. For example, the UE 124 can only receive sidelink DRX preferences from the UE 102 upon receiving permission from the WANN 118.

[0041] To prevent the UE from frequently reporting sidelink DRX preferences, the WANN 118 can configure a DRX preference prohibit timer, e.g., drx-PreferenceProhibitTimer, for the UE. In one implementation, the UE 102 can receive the DRX preference prohibit timer from the WANN 118. While the DRX preference prohibit timer is running, the UE 102 can suspend sending sidelink DRX preferences to the WANN 118 until the DRX preference prohibit timer is stopped or expires. Additionally or alternatively, the UE 124 can configure a DRX preference prohibit timer for the UE 102. While the DRX preference prohibit timer configured by the UE 124 is running, the UE 102 can not send its sidelink DRX preferences for the sidelink communication link between the UE 102 and the UE 124 to the UE 124 until the DRX preference prohibit timer is stopped or expires.

[0042] In another implementation, the DRX preference prohibit timer is not running. In this case, the UE 102 can start or restart the DRX preference prohibit timer upon sending a sidelink DRX preference for the sidelink communication link to the UE 124 or the WANN 118.

[0043] Further, when sidelink hybrid automatic repeat request (HARQ) feedback is enabled for the sidelink communication link between UE 102 and UE 124, sidelink DRX retransmission is allowed between UE 102 and UE 124. In an implementation, UE 102 can receive an indication to enable HARQ feedback via sidelink control information. The sidelink control information can be sent from WANN 118 or UE 124. As a receiving UE, UE 102 can have a plurality of HARQ processes, each corresponding to a respective data packet to be sent via the sidelink communication link between UE 102 and UE 124. Upon receiving the indication to enable HARQ feedback, UE 102 can send sidelink HARQ feedback information for one or more HARQ processes and then start a respective sidelink DRX HARQ round trip time (RTT) timer, e.g., drx-HARQ-RTT-TimerRxSL, for each of the one or more HARQ processes. In the event that UE 102 fails to decode a received data packet corresponding to a HARQ process, UE 102 can start a sidelink DRX retransmission timer, e.g., drx-RetransmissionTimerRxSL, for the HARQ process upon expiration of the sidelink DRX HARQ RTT timer for the HARQ process. In this case, UE 102 can assume that DRX is not used for the sidelink communication link during the sidelink DRX retransmission timer is running. UE 102 can receive configuration for the sidelink DRX HARQ RTT timer and the sidelink DRX retransmission timer from WANN 118 or UE 124.

[0044] Optionally, the UE 102 can configure a physical uplink control channel to request sidelink retransmission resources. To disable downlink DRX for downlink between the UE 102 and the WANN 118 during reception of the sidelink retransmission resources from the WANN 118, the WANN 118 can configure a downlink sidelink HARQ RTT timer (e.g., drx-HARQ-RTT-TimerSL DL) and a downlink sidelink retransmission timer (e.g., drx-RetransmissionTimerSL DL) for a sidelink HARQ process. In an implementation, the UE 102 can start the downlink sidelink HARQ RTT timer for the sidelink HARQ process after the transmission of the indication of the retransmission allows the sidelink HARQ feedback. The UE 102 can then start the downlink sidelink retransmission timer for the sidelink HARQ process upon expiration of the downlink sidelink HARQ RTT timer. During the running of the downlink sidelink retransmission timer, the UE 102 can assume that the downlink DRX for the downlink between the UE 102 and the WANN 118 is not used. The UE 102 can receive the sidelink retransmission resources from the WANN 118 via the downlink without the downlink DRX.

[0045] Figure 4 An example implementation 400 for a second user equipment (such as the UE 124) assisting a first user equipment (such as the UE 102) in configuring a sidelink DRX for a sidelink communication link between the UE 102 and the UE 124 is shown. For example, the operations of the second user equipment (such as the UE 124) assisting the first user equipment (such as the UE 102) in configuring the sidelink DRX for the sidelink communication link between the UE 102 and the UE 124 will be described with reference to Figure 1 and Figure 4

[0046] The UE 124 can transmit second DRX configuration information to the UE 102 (410). In an implementation, the UE 124 can configure the second DRX configuration information and transmit the second DRX configuration information to the UE 102 via a PC5 RRC dedicated message or a broadcast message.

[0047] The second DRX configuration information can facilitate the UE 102 to configure a sidelink DRX configuration scheme for the sidelink communication between the UE 102 and the UE 124. For example, as described above with reference to Figure 2 ​As discussed, the UE 102 can configure the sidelink DRX configuration scheme based on the first DRX configuration information received from the wireless network access node, such as the WANN 118, and the second DRX configuration information. The second DRX configuration information can include a subset of the complete set of DRX configuration parameters used to configure the sidelink DRX configuration scheme. The second DRX configuration information can include, for example, a duration, an on-duration time pattern, a first inactivity timer, and a second inactivity timer.

[0048] Optionally, in coordination with the UE 102 to utilize a sidelink DRX inactivity timer, the running of the sidelink DRX inactivity timer can indicate that the UE 102 and the UE 124 can perform sidelink communications without DRX. The UE 124 can configure a sidelink transmission DRX inactivity timer for the sidelink communication link between the UE 102 and the UE 124. The sidelink transmission DRX inactivity timer can correspond to the sidelink DRX inactivity timer configured to the UE 102 for the sidelink communication link. The UE 124 can start or restart the sidelink transmission DRX inactivity timer for the sidelink communication link when the UE 124 receives or transmits a control message indicating a new transmission on the sidelink communication link between the UE 102 and the UE 124, for example, via a physical sidelink control channel. Additionally or alternatively, the UE 124 can start or restart the sidelink transmission DRX inactivity timer for the sidelink communication link when the UE 124 receives or transmits a sidelink DRX command MAC CE for the sidelink communication link between the UE 102 and the UE 124. The UE 124 can receive a timer configuration for the sidelink transmission DRX inactivity timer from the WANN 118 or the UE 102.

[0049] Optionally, in a case that the UE 124 determines that the selected sidelink grant cannot be used according to the DRX configuration scheme determined by the UE 102, the UE 124 can trigger sidelink transmission resource reselection. In a case that the UE 124 determines that the selected sidelink grant is outside of a sidelink transmission DRX non-use period, the UE 124 can trigger sidelink transmission resource reselection. In a case that the UE 124 determines that the selected sidelink grant is outside of a running period of a sidelink transmission DRX inactivity timer, the UE 124 can trigger sidelink transmission resource reselection. In a case that the UE 124 determines that the selected sidelink grant is outside of a running period of a sidelink DRX inactivity timer of the UE 102, the UE 124 can trigger sidelink transmission resource reselection.

[0050] In addition, the UE 102 can establish sidelink communication links with multiple user equipments, such as UE 124 and UE 126, and receive data packets from both UE 124 and UE 126 via the sidelink communication links. The UE 124 can maintain a sidelink transmission DRX inactivity timer 1 for the sidelink communication link between the UE 102 and the UE 124. The UE 126 can maintain a sidelink transmission DRX inactivity timer 2 for the sidelink communication link between the UE 102 and the UE 126. However, the UE 124 can not know whether the sidelink transmission DRX inactivity timer 2 of the UE 126 is running. Similarly, the UE 126 can not know whether the sidelink transmission DRX inactivity timer 1 of the UE 124 is running. In the event that the sidelink transmission DRX inactivity timer 1 stops while the sidelink transmission inactivity timer 2 is running, the UE 124 can stop transmitting data to the UE 102, while the UE 126 can continue transmitting data to the UE 102. Because the UE 102 needs to receive the data transmitted from the UE 126, the UE 102 can have to monitor all of its sidelink communication links, including the communication link between the UE 102 and the UE 124. At this point, the UE 124 can actually continue transmitting data to the UE 102 instead of stopping transmission to wait for the next sidelink DRX on duration for transmission. To enable the UE 124 to resume sidelink transmission, the UE 102 can transmit an indication message to inform the UE 124 to start the sidelink transmission DRX inactivity timer 1 of the UE 124.

[0051] In an implementation, the UE 124 can receive control information for the sidelink transmission DRX inactivity timer from the UE 102. The control information can indicate to start or stop the sidelink transmission DRX inactivity timer. Upon receiving the control information, the UE 124 can transmit a reception acknowledgement of the control information to the UE 102. The UE 124 can then start or stop the sidelink transmission DRX inactivity timer according to the control message.

[0052] In the event that the UE 124 receives control information indicating to start the sidelink transmission DRX inactivity timer but subsequently fails to receive control information indicating to stop the sidelink transmission DRX inactivity timer, the UE 124 can stop the sidelink transmission DRX inactivity timer upon expiration of the sidelink transmission DRX inactivity timer. Additionally or alternatively, the UE 124 can stop the sidelink transmission DRX inactivity timer after a predetermined number of sidelink DRX periods from the start of the sidelink transmission DRX inactivity timer.

[0053] Optionally, in the case where the UE 102 wants to report sidelink DRX preferences, the WANN 118 can configure whether the UE 124 is allowed to receive the sidelink DRX preferences from the UE 102. In an implementation, the UE 124 can only receive the sidelink DRX preferences from the UE 102 upon receiving permission from the WANN 118.

[0054] Further, as discussed above with reference to Figure 2 Sidelink DRX retransmission can be performed between the UE 102 and the UE 124 when sidelink hybrid automatic repeat request (HARQ) feedback is enabled for the sidelink communication link between the UE 102 and the UE 124. In an implementation, the UE 124 can receive an indication from the WANN 118 to enable HARQ feedback via sidelink control information, for example. As the transmitting UE, the UE 124 can have a plurality of HARQ processes, each corresponding to a respective data packet to be transmitted via the sidelink communication link between the UE 102 and the UE 124. For each of the HARQ processes, the UE 124, upon receiving the indication to enable HARQ feedback, can perform a first repetition of the PSSCH transmission to the UE 102 corresponding to the HARQ process and then start a sidelink transmission DRX HARQ RTT timer, e.g., drx-HARQ-RTT-TimerTxSL. When the sidelink transmission DRX HARQ RTT timer for a HARQ process expires, the UE 102 can start a sidelink transmission DRX retransmission timer for the HARQ process, e.g., drx-RetransmissionTimerTxSL. The UE 124 can retransmit the data packet for the HARQ process to the UE 102 during the running of the sidelink transmission DRX retransmission timer. The UE 124 can receive configuration for the sidelink transmission DRX HARQ RTT timer and the sidelink transmission DRX retransmission timer from the WANN 118 or the UE 102.

[0055] Optionally, the UE 124 can configure a physical uplink control channel to request the sidelink retransmission resource. To disable downlink DRX for downlink between the UE 124 and the WANN 118 during reception of the sidelink retransmission resource from the WANN 118, the WANN 118 can configure a downlink sidelink HARQ RTT timer (e.g., drx-HARQ-RTT-TimerSL DL) and a downlink sidelink retransmission timer (e.g., drx-RetransmissionTimerSL DL) for a sidelink HARQ process. In an implementation, the UE 124 can start the downlink sidelink HARQ RTT timer for the sidelink HARQ process after the transmission of the indication of the retransmission is allowed. Then, the UE 124 can start the downlink sidelink retransmission timer for the sidelink HARQ process when the downlink sidelink HARQ RTT timer expires. During the running of the downlink sidelink retransmission timer, the UE 124 can determine not to use the downlink DRX for the downlink between the UE 124 and the WANN 118. The UE 124 can receive the sidelink retransmission resource from the WANN 118 via the downlink without the downlink DRX.

[0056] Throughout the specification and claims, unless otherwise indicated, the terms "may" and "may be" are used in a permissive sense (i.e., meaning having the potential to, being able to, or maybe capable of), rather than the peremptory sense (i.e., meaning must be, will be, or shall be). Similarly, the phrases "in an embodiment" or "in another embodiment" as used herein do not necessarily refer to the same embodiment, although they can. For example, the subject matter can be implemented in a variety of embodiments, all of which need not include the same features, functionalities, or structures. Also, although the subject matter can be implemented in a variety of embodiments, the subject matter can be implemented in other embodiments not expressly described herein.

[0057] Generally, terminology can be understood at least in part from usage in context. For example, terms, such as "and", "or", or "and / or", as used herein can include a variety of meanings that can depend, at least in part, upon the context in which such terms are used. Typically, "or" if used to associate a list, such as A, B, or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B or C, here used in the exclusive sense. In addition, the term "one or more" as used herein, at least in part, depending on the context, can be taken to mean any feature, structure or characteristic of at least one, or any combination of two or more features, structures or characteristics. Likewise, terms, such as "a", "an", or "the", unless specifically stated otherwise, can be understood to convey a singular sense or a plural sense, at least in part, depending on the context in which such terms are used. Further, the term "based on" can be understood as not necessarily requiring exclusive factor sets, but rather, can allow for additional factors to be present, again, at least in part, depending on the context.

[0058] Reference throughout this specification to features, advantages, or similar language does not mean that all of the features and advantages that can be achieved in accordance with the present technology should be or are in any single implementation. Rather, language relating to features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included within at least one implementation of the present technology. Accordingly, discussions utilising terms such as features, advantages, or similar language, throughout the specification, can but do not necessarily refer to the same embodiment.

[0059] Further, the described features, advantages, and characteristics of the technology can be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize, in light of the description herein, that the technology can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages can be recognized in light of the descriptions herein.

Claims

1. A method performed by a first user equipment in a wireless communication network, the method comprising: receiving first discontinuous reception, DRX, configuration information from a wireless network access node; receiving second DRX configuration information from a second user equipment; and obtaining a DRX configuration scheme for sidelink communication between the first user equipment and the second user equipment based on the first DRX configuration information and the second DRX configuration information; wherein the first user equipment configures a sidelink DRX inactivity timer for a sidelink communication link between the first user equipment and the second user equipment, the sidelink DRX inactivity timer, when running, indicates that DRX is not to be used for the sidelink communication link, the method further comprising: stopping the sidelink DRX inactivity timer in response to receiving a sidelink DRX command medium access control, MAC, control element, CE, for the sidelink communication link. the DRX configuration scheme comprises a plurality of DRX configuration parameters, the obtaining the DRX configuration scheme comprising:

2. The method of claim 1, wherein, combining DRX configuration parameters in the first DRX configuration information and DRX configuration parameters in the second DRX configuration information into the DRX configuration scheme. the combining comprises:

3. The method of claim 2, wherein, assigning values of DRX configuration parameters in the second DRX configuration information to corresponding DRX configuration parameters in the DRX configuration scheme; and in response to the second DRX configuration information not including a DRX configuration parameter corresponding to a first DRX configuration parameter in the DRX configuration scheme, assigning a value of the first DRX configuration parameter in the first DRX configuration information to the first DRX configuration parameter in the DRX configuration scheme. the combining comprises:

4. The method of claim 2, wherein, in response to failing to receive the second DRX configuration information from the second user equipment, using the first DRX configuration information as the DRX configuration scheme.

5. The method of claim 1, further comprising: receiving third DRX configuration information from a third user equipment; and the obtaining the DRX configuration scheme comprises: determining the DRX configuration scheme based on the first DRX configuration information, the second DRX configuration information, and the third DRX configuration information. the determining the DRX configuration scheme comprises: assigning values of DRX configuration parameters in the second DRX configuration information to corresponding DRX configuration parameters in the DRX configuration scheme; and 6. The method of claim 5, wherein, in response to the second DRX configuration information not including a DRX configuration parameter corresponding to a first DRX configuration parameter in the DRX configuration scheme, searching for a second DRX configuration parameter corresponding to the first DRX configuration parameter in the first DRX configuration information and the third DRX configuration information; and assigning a value of the second DRX configuration parameter to the first DRX configuration parameter.

7. The method of claim 1, further comprising: prior to receiving the second DRX configuration information, transmitting the first DRX configuration information to the second user equipment. ​ ​ 8. The method of claim 1, wherein, The first DRX configuration information includes at least a DRX configuration parameter of a long cycle start offset, a long cycle, or a start offset.

9. The method of claim 1, wherein, The second DRX configuration information includes at least a DRX configuration parameter of a duration, an on duration time pattern, a first inactivity timer, or a second inactivity timer.

10. The method of claim 1, further comprising: transmitting, to the wireless network access node, sidelink information of the first user equipment before receiving the first DRX configuration information, the sidelink information including at least one of quality of service information, destination identification information, or sidelink assistance information.

11. The method of claim 1, further comprising: transmitting, to the wireless network access node, a sidelink DRX preference for the sidelink communication link in response to receiving an indication from the wireless network access node that the first user equipment is allowed to report the sidelink DRX preference to the wireless network access node.

12. The method of claim 1, further comprising: transmitting, to the second user equipment, a sidelink DRX preference for the sidelink communication link in response to receiving an indication from the wireless network access node that the first user equipment is allowed to report the sidelink DRX preference to the second user equipment.

13. The method of claim 11 or 12, wherein, The sidelink DRX preference includes at least one of a preferred DRX inactivity timer, a preferred DRX long cycle, a preferred DRX short cycle, or a preferred DRX short cycle timer.

14. The method of claim 11 or 12, further comprising: receiving a DRX preference prohibit timer from the wireless network access node or the second user equipment; and suspending transmission of the sidelink DRX preference to the wireless network access node or the second user equipment in response to the DRX preference prohibit timer being running until the DRX preference prohibit timer stops.

15. The method of claim 14, further comprising: starting or restarting the DRX preference prohibit timer in response to transmitting a sidelink DRX preference for the sidelink communication link to the wireless network access node or the second user equipment.

16. The method of claim 1, further comprising: starting a sidelink DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer for a HARQ process at an end of transmission of sidelink HARQ feedback in response to sidelink HARQ feedback being enabled; and starting a sidelink DRX retransmission timer for the HARQ process at an expiration of the sidelink DRX HARQ RTT timer in response to a packet of the HARQ process failing to be decoded; and determining that DRX is not used for the sidelink communication link during the sidelink DRX retransmission timer is running.

17. The method of claim 16, further comprising: starting a downlink sidelink HARQ RTT timer for the HARQ process at an end of the sidelink HARQ feedback transmission in response to the first user equipment being configured a physical uplink control channel to request a sidelink retransmission resource; and ​ ​ starting a downlink sidelink retransmission timer for the HARQ process upon expiry of the downlink sidelink HARQ RTT timer.

18. The method of claim 17, wherein, during running of the downlink sidelink retransmission timer, downlink DRX is not used between the wireless network access node and the first user equipment.

19. A method performed by a second user equipment in a wireless communication network, the method comprising: sending, to a first user equipment, second discontinuous reception, DRX, configuration information that helps the first user equipment determine a DRX configuration scheme for sidelink communication between the first user equipment and the second user equipment based on the second DRX configuration information and first DRX configuration information received from a wireless network access node; wherein the first user equipment configures a sidelink DRX inactivity timer for a sidelink communication link between the first user equipment and the second user equipment, the sidelink DRX inactivity timer, when running, indicates that DRX is not used for the sidelink communication link, and the first user equipment stops the sidelink DRX inactivity timer in response to receiving a sidelink DRX command medium access control, MAC, control element, CE, for the sidelink communication link.

20. The method of claim 19, wherein, the second user equipment configures a sidelink transmission DRX inactivity timer for a sidelink communication link between the first user equipment and the second user equipment, the method further comprising: starting or restarting the sidelink transmission DRX inactivity timer for the sidelink communication link in response to transmitting a control message indicating a new transmission on the sidelink communication link.

21. The method of claim 20, further comprising: starting or restarting the sidelink transmission DRX inactivity timer for the sidelink communication link in response to transmission of a sidelink DRX command medium access control, MAC, control element, CE, for the sidelink communication link.

22. The method of claim 20, further comprising: receiving timer configuration for the sidelink transmission DRX inactivity timer from the wireless network access node or the first user equipment.

23. The method of claim 20, further comprising: triggering sidelink transmission resource reselection in response to determining that a selected sidelink grant cannot be used according to the DRX configuration scheme determined by the first user equipment.

24. The method of claim 19, further comprising: triggering sidelink transmission resource reselection in response to determining that a selected sidelink grant is outside of a sidelink transmission DRX non-use period.

25. The method of claim 20, further comprising: triggering sidelink transmission resource reselection in response to determining that a selected sidelink grant is outside of a running period of the sidelink transmission DRX inactivity timer.

26. The method of claim 20, further comprising: in response to determining that the selected sidelink grant is outside of an active period of a sidelink DRX inactivity timer of the first user equipment, triggering sidelink transmission resource reselection, the sidelink DRX inactivity timer, when running, indicating that the DRX is not to be used for the sidelink communication link.

27. The method of claim 20, further comprising: receiving control information from the first user equipment for the sidelink transmission DRX inactivity timer; and controlling the sidelink transmission DRX inactivity timer in accordance with the control information.

28. The method of claim 27, further comprising: sending an acknowledgement of receipt of the control information to the first user equipment.

29. The method of claim 27, further comprising: in response to not receiving control information indicating to stop the sidelink transmission DRX inactivity timer, stopping the sidelink transmission DRX inactivity timer upon expiration of the sidelink transmission DRX inactivity timer or after a predetermined number of sidelink DRX periods from the start of the sidelink transmission DRX inactivity timer.

30. The method of claim 20, further comprising: in response to receiving an indication from the wireless network access node that the second user equipment is allowed to receive sidelink DRX preferences from the first user equipment, receiving sidelink DRX preferences from the first user equipment for the sidelink communication link.

31. The method of claim 20, further comprising: in response to sidelink hybrid automatic repeat request (HARQ) feedback being enabled, starting a sidelink transmission DRX HARQ round trip time (RTT) timer for a HARQ process at the end of a retransmission for the sidelink HARQ feedback; starting a sidelink transmission DRX retransmission timer for the HARQ process upon expiration of the sidelink transmission DRX HARQ RTT timer; and retransmitting a data packet for the HARQ process during a running period of the sidelink transmission DRX retransmission timer.

32. An apparatus comprising a processor and a memory, wherein, the processor is configured to read computer code from the memory to implement the method of any one of claims 1 to 31.

33. A computer readable medium comprising instructions which, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 31.

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