Discontinuous reception operation for sidelink communications

Abstract

Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a user equipment (UE) may receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure, the configuration indicating a duration of a timer associated with an active period for a first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure. The UE may then receive a first sidelink communication including data and possibly transmit feedback requesting retransmission of the data. The UE may then receive a second sidelink communication including the retransmitted data. Before receiving the second sidelink communication including the retransmitted data, the UE may start a timer according to the configuration. Thus, the UE may be in an active mode to receive the second sidelink communication.

Description

[Technical Field]

[0001] cross reference This patent application claims the benefit of U.S. Patent Application No. 17 / 313,654, entitled "DISCONTINUOUS RECEPTION OPERATION FOR SIDELINK COMMUNICATIONS," filed May 6, 2021, by ZHANG et al., which is assigned to the assignee of the present application.

[0002] The following relates to wireless communications including discontinuous reception operations for sidelink communications. [Background technology]

[0003] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, and broadcasts. These systems may be capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth-generation (4G) systems, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), or LTE-A Pro systems, and fifth-generation (5G) systems, sometimes referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple-access communication system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, sometimes known as user equipment (UE). Summary of the Invention [Means for solving the problem]

[0004] The disclosed techniques relate to improved methods, systems, devices, and apparatuses that support discontinuous reception operation for sidelink communications. That is, a user equipment (UE) may communicate with another UE during a sidelink discontinuous reception procedure, where the UE transitions between an active period (e.g., the UE monitors sidelink communications) and an inactive period (e.g., the UE refrains from monitoring sidelink communications). In some cases, the active period for a UE (e.g., during a discontinuous reception procedure for sidelink communications) may be defined based on a timer. For example, the UE may enter the active period in response to starting a timer and transition to the inactive period based on the expiration of the timer. In general, the described techniques provide a sidelink discontinuous reception procedure configuration that indicates the duration of a timer (e.g., associated with an active period for the UE) so that the UE is in the active period to receive data retransmissions from another UE as part of the sidelink discontinuous reception procedure.

[0005] In some examples, the configuration for the sidelink discontinuous reception procedure (and the corresponding configuration for the timer) may be based on the type of sidelink discontinuous reception procedure (e.g., a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, a sidelink discontinuous reception procedure associated with receiving an identifier that identifies a UE in sidelink communication, a sidelink discontinuous reception procedure associated with blind retransmissions).

[0006] A method for wireless communication in a first user equipment (UE) is described. The method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure; receiving a first sidelink communication from a second UE based on the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure, the first sidelink communication including data, transmitting feedback to the second UE based on receiving the first sidelink communication requesting a retransmission of the data, starting the timer in response to transmitting the feedback based on receiving the first sidelink communication, and receiving a second sidelink communication including the retransmission of the data based on starting the timer, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0007] An apparatus for wireless communication in a first UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure; receive a first sidelink communication from a second UE including data based on receiving the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure; transmit feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication; initiate the timer in response to transmitting the feedback based on receiving the first sidelink communication; and receive a second sidelink communication including the retransmission of the data based on initiating the timer, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0008] Another apparatus for wireless communication in a first UE is described. The apparatus may include: means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure; means for receiving a first sidelink communication from a second UE based on the receiving control signaling indicating the configuration for performing the sidelink discontinuous reception procedure, means for transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication, means for starting the timer in response to transmitting the feedback based on receiving the first sidelink communication, and means for receiving a second sidelink communication including the retransmission of the data, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure based on starting the timer.

[0009] A non-transitory computer-readable medium storing code for wireless communication in a first UE is described, the code may include instructions executable by a processor to: receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure; receive a first sidelink communication from a second UE including data based on receiving the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure; transmit feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication; start the timer in response to transmitting the feedback based on receiving the first sidelink communication; and receive a second sidelink communication including the retransmission of the data based on starting the timer, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0010] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for starting, in response to transmitting the feedback, a second timer associated with an inactivity period for the first UE to receive sidelink transmissions during the sidelink discontinuous reception procedure, wherein starting the timer associated with the activity period for the first UE may be based on starting the second timer.

[0011] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, expiration of the second timer triggers starting a timer associated with an active period for the first UE.

[0012] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for identifying a time for starting a timer associated with an active period for receiving sidelink retransmissions for the first UE from a first time associated with expiry of the second timer and a second time indicated by the configuration for performing a sidelink discontinuous reception procedure corresponding to a time period prior to the resource for receiving the second sidelink communication, where starting the timer may be based on the identifying.

[0013] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, initiating a timer in response to transmitting feedback may include an act, feature, means, or instruction for initiating a timer based on a sidelink resource reservation procedure at a time indicated by the configuration for performing a sidelink discontinuous reception procedure.

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the time indicated by the configuration corresponds to a time period prior to the resources for receiving the second sidelink communication.

[0015] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first sidelink communication includes control information indicating resources associated with a sidelink resource reservation procedure for receiving the second sidelink communication.

[0016] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting feedback may include an operation, feature, means, or instruction for transmitting a hybrid automatic repeat request (HARQ) to request a retransmission of the data based on a failure to decode the data in the first sidelink communication.

[0017] A method for wireless communication in a first UE is described. The method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in a sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE, receiving a first sidelink communication from a second UE based on receiving the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure, the first sidelink communication including control information including at least a portion of the identifier of the first UE and data including the identifier of the first UE, transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication and the data including the identifier of the first UE, initiating a timer based on receiving the first sidelink communication, and receiving a second sidelink communication including the retransmission of the data based on initiating the timer.

[0018] An apparatus for wireless communication in a first UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in a sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE; receive a first sidelink communication from a second UE based on receiving the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure, the first sidelink communication including control information including at least a portion of the identifier of the first UE and data including the identifier of the first UE; transmit feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication and the data including the identifier of the first UE; initiate a timer based on receiving the first sidelink communication; and receive a second sidelink communication including the retransmission of the data based on initiating the timer.

[0019] Another apparatus for wireless communication in a first UE is described. The apparatus may include: means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in a sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE; means for receiving from a second UE a first sidelink communication including control information including at least a portion of an identifier of the first UE and data including the identifier of the first UE based on receiving the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure; means for transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication and the data including the identifier of the first UE; means for initiating a timer based on receiving the first sidelink communication; and means for receiving a second sidelink communication including the retransmission of the data based on initiating the timer.

[0020] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to: receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in a sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE; receive from a second UE a first sidelink communication including control information including at least a portion of an identifier of the first UE and data including the identifier of the first UE based on receiving the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure; send feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication and the data including the identifier of the first UE; start a timer based on receiving the first sidelink communication; and receive a second sidelink communication including the retransmission of the data based on starting the timer.

[0021] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, starting the timer may include an act, feature, means, or instruction for starting the timer at a time indicated by the configuration for performing a sidelink discontinuous reception procedure based on identifying that the data includes an identifier of the first UE.

[0022] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the time indicated by the configuration corresponds to a first time period after receiving a first sidelink communication, a second time period after transmitting feedback, or a combination thereof.

[0023] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: receiving from the second UE a third sidelink communication including second control information including at least a portion of a second identifier of the third UE and second data including the second identifier of the third UE based on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure; starting a timer in response to detecting the second control information in the third sidelink communication; identifying that the second identifier of the third UE may differ from the identifier of the first UE based on starting the timer and receiving the third sidelink communication; and resetting the timer based on identifying that the second identifier of the third UE may differ from the identifier of the first UE.

[0024] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, initiating a timer may include an act, feature, means, or instruction for initiating a timer in response to detecting control information in the first sidelink communication, and sending the feedback may be based on initiating the timer.

[0025] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving from the second UE a third sidelink communication including second control information including at least a portion of a second identifier of the third UE based on receiving the control signaling indicating a configuration for performing a sidelink discontinuous reception procedure, and refraining from decoding second data included in the third sidelink communication based on the portion of the second identifier of the third UE being different from the portion of the identifier of the first UE.

[0026] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the identifier that identifies the UE may be a media access control (MAC) address that identifies the UE in sidelink communications.

[0027] A method for wireless communication in a first UE is described. The method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for the sidelink communication, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure; receiving a first sidelink communication from a second UE including data based on receiving the configuration for performing the sidelink discontinuous reception procedure; initiating the timer based on receiving the first sidelink communication; and receiving a second sidelink communication including the blind retransmission of the data based on initiating the timer.

[0028] An apparatus for wireless communication in a first UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communication, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure; receive a first sidelink communication from a second UE including data based on receiving the configuration for performing the sidelink discontinuous reception procedure; initiate the timer based on receiving the first sidelink communication; and receive a second sidelink communication including the blind retransmission of the data based on initiating the timer.

[0029] Another apparatus for wireless communication in a first UE is described. The apparatus may include: means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for the sidelink communication, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure; means for receiving a first sidelink communication from a second UE based on receiving the configuration for performing the sidelink discontinuous reception procedure, the first sidelink communication including data; means for initiating the timer based on receiving the first sidelink communication; and means for receiving a second sidelink communication including the blind retransmission of the data based on initiating the timer.

[0030] A non-transitory computer-readable medium storing code for wireless communication in a first UE is described. The code may include instructions executable by a processor to: receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communication, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure; receive a first sidelink communication from a second UE including data based on receiving the configuration for performing the sidelink discontinuous reception procedure; start the timer based on receiving the first sidelink communication; and receive a second sidelink communication including the blind retransmission of the data based on starting the timer.

[0031] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, feature, means, or instruction for restarting a timer in response to receiving a second sidelink communication including a blind retransmission of data.

[0032] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for determining, based on control information included in the first sidelink communication, that data in the first sidelink communication may be associated with a new transmission, wherein starting the timer may be based on the data in the first sidelink communication being associated with the new transmission; and refraining from restarting the timer after receiving a second sidelink communication based on the second sidelink communication including a blind retransmission of the data. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 illustrates an example wireless communication system supporting discontinuous reception operation for sidelink communications, according to aspects of the present disclosure. [Figure 2] FIG. 1 illustrates an example wireless communication system supporting discontinuous reception operation for sidelink communications, according to aspects of the present disclosure. [Figure 3] FIG. 10 is an example timing diagram supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 4] FIG. 10 is an example timing diagram supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 5] FIG. 10 is an example timing diagram supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 6] FIG. 1 illustrates an example process flow for supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 7] FIG. 1 illustrates an example process flow for supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 8] FIG. 1 illustrates an example process flow for supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 9]FIG. 10 is a block diagram of a device supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 10] FIG. 10 is a block diagram of a device supporting discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 11] FIG. 10 is a block diagram of a communications manager supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. [Figure 12] FIG. 1 is a diagram of a system including a device that supports discontinuous reception operation for sidelink communications, according to an aspect of the present disclosure. [Figure 13] 10 is a flowchart illustrating a method for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. [Figure 14] 10 is a flowchart illustrating a method for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. [Figure 15] 10 is a flowchart illustrating a method for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. [Figure 16] 10 is a flowchart illustrating a method for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. [Figure 17] 10 is a flowchart illustrating a method for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. [Figure 18] 10 is a flowchart illustrating a method for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0034] Some wireless communication systems may support a sidelink discontinuous reception procedure, in which a user equipment (UE) transitions between an active period (e.g., the UE monitors sidelink communications) and an inactive period (e.g., the UE refrains from monitoring sidelink communications). Relying on discontinuous reception for sidelink communications (e.g., when compared to a procedure for sidelink communications in which the UE is continuously active) may result in reduced power usage at the UE. In some cases, the active period for a UE (e.g., during a discontinuous reception procedure for sidelink communications) may be defined by a timer. That is, the UE may enter the active period in response to starting a timer and transition to the inactive period based on expiration of the timer. In general, the described techniques provide a sidelink discontinuous reception procedure configuration that indicates the duration of a timer (e.g., associated with an active period for the UE) so that the UE is in the active period to receive data retransmissions from another UE as part of the sidelink discontinuous reception procedure.

[0035] In an example of a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, a UE may start a timer in response to sending feedback requesting a retransmission of data received from another UE and may receive the retransmission based on starting the timer. In some cases, the UE may start the timer in response to expiration of a different timer (e.g., associated with an inactivity period) that is started based on sending feedback requesting the retransmission. In some other cases, the UE may start the timer at a time indicated by a configuration (e.g., associated with the sidelink discontinuous reception procedure).

[0036] In an example of a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in a sidelink communication, the UE may start a timer based on receiving a first sidelink communication (e.g., including an identifier associated with the UE) and subsequently receive a retransmission of data (e.g., originally included in the first sidelink communication) based on starting the timer. In the first case, the UE may start the timer based on the first sidelink communication including an identifier associated with the UE at a time indicated by a configuration. In another case, the UE may start the timer based on receiving the first sidelink communication (e.g., before determining whether the first sidelink communication includes an identifier associated with the UE). Here, the UE may optionally reset the timer if the first sidelink communication does not include an identifier associated with the UE (e.g., and does not receive a retransmission).

[0037] In an example of a sidelink discontinuous reception procedure associated with blind retransmissions, the UE may start a timer in response to receiving the first sidelink transmission. In some cases, the UE may start the timer if the sidelink transmission contains new data (e.g., instead of retransmitted data). In other cases, the UE may additionally start the timer if the sidelink transmission contains data retransmissions.

[0038] Aspects of the present disclosure are first described in the context of a wireless communication system. Aspects of the present disclosure are then described in the context of timing diagrams and process flows. Aspects of the present disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts relating to discontinuous reception operations for sidelink communications.

[0039] 1 illustrates an example of a wireless communication system 100 supporting discontinuous reception operation for sidelink communications in accordance with an aspect of the present disclosure. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low-latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

[0040] The base stations 105 may be dispersed throughout a geographic area to form the wireless communication system 100 and may be devices of different forms or with different capabilities. The base stations 105 and the UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which the UEs 115 and the base station 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 may support communication of signals according to one or more radio access technologies.

[0041] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile or both at different times. The UEs 115 may be devices of different forms or with different capabilities. Some example UEs 115 are shown in FIG. 1. The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115, base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment), as shown in FIG. 1.

[0042] The base stations 105 may communicate with the core network 130, with each other, or both. For example, the base stations 105 may interface with the core network 130 through one or more backhaul links 120 (e.g., via an S1, N2, N3, or other interface). The base stations 105 may communicate with each other through the backhaul links 120 (e.g., via an X2, Xn, or other interface), either directly (e.g., directly between base stations 105), or indirectly (e.g., via the core network 130), or both. In some examples, the backhaul links 120 may be or include one or more wireless links.

[0043] One or more of the base stations 105 described herein may include, or may be referred to by those skilled in the art as, a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next generation NodeB or giga-NodeB (any of which may be referred to as a gNB), a Home NodeB, a Home eNodeB, or other suitable terminology.

[0044] The UE 115 may include or be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, and a “device” may also be referred to as a unit, a station, a terminal, or a client, among other things. The UE 115 may also include or be referred to as a personal electronic device, such as a mobile phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, the UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine-type communication (MTC) device, among other things, which may be implemented in various items such as an appliance, a vehicle, a meter, or the like.

[0045] The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115, which may act as relays, as shown in FIG. 1, as well as base stations 105 and network equipment, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among others.

[0046] The UE 115 and the base station 105 may communicate wirelessly with each other via one or more communication links 125 on one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier used for the communication link 125 may include a portion (e.g., a bandwidth portion (BWP)) of a radio frequency spectrum band operating according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling coordinating operation on the carrier, user data, or other signaling. The wireless communication system 100 may support communication with the UE 115 using carrier aggregation or multi-carrier operation. The UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation can be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers.

[0047] A signal waveform transmitted on a carrier may be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Thus, the more resource elements and the higher the order of the modulation scheme that the UE 115 receives, the higher the data rate of the UE 115 may be. Wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase the data rate or data integrity for communications with the UE 115.

[0048] The time interval for the base station 105 or the UE 115 may be, for example, T s =1 / (Δf max N f ) seconds, where Δf max may represent the maximum supported subcarrier spacing, and N f may represent the maximum supported discrete Fourier transform (DFT) size. The communication resource time intervals may be organized according to radio frames, each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0049] Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into several slots. Alternatively, each frame may include a variable number of slots, and the number of slots may depend on the subcarrier spacing. Each slot may include several symbol periods (e.g., depending on the length of a cyclic prefix prepended to each symbol period). In some wireless communications systems 100, a slot may be further divided into multiple minislots, each containing one or more symbols. Excluding the cyclic prefix, each symbol period may include one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the frequency band of operation.

[0050] A subframe, slot, minislot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

[0051] Physical channels may be multiplexed on carriers according to various techniques. Physical control channels and physical data channels may be multiplexed on downlink carriers using, for example, one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by a number of symbol periods and may extend across the system bandwidth of the carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESETs) may be configured for a set of UEs 115. For example, one or more of the UEs 115 may monitor or search the control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates at one or more aggregation levels configured in a cascaded manner. The aggregation level for a control channel candidate may refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for sending control information to multiple UEs 115 and a UE-specific search space set for sending control information to a particular UE 115 .

[0052] In some examples, the base stations 105 may be mobile and therefore may provide communication coverage to moving geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, although the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communication system 100 may include a heterogeneous network, for example, where different types of base stations 105 provide coverage to various geographic coverage areas 110 using the same or different radio access technologies.

[0053] The wireless communication system 100 may be configured to support ultra-reliable or low-latency communications, or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communications (URLLC) or mission-critical communications. The UE 115 may be designed to support ultra-reliable, low-latency, or critical functionality (e.g., mission-critical functionality). Ultra-reliable communications may include private or group communications and may be supported by one or more mission-critical services, such as mission critical push-to-talk (MCPTT), mission critical video (MCVideo), or mission critical data (MCData). Support for mission-critical functionality may include service prioritization, and the mission-critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency may be used interchangeably herein.

[0054] In some examples, the UE 115 may also be able to communicate directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) protocol or a D2D protocol). One or more UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105 or may in some cases be unable to receive transmissions from the base station 105. In some examples, a group of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system in which each UE 115 transmits to every other UE 115 in the group. In some examples, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without the involvement of the base station 105.

[0055] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) that manages access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)) that routes packets or interconnects to external networks. The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the core network 130. User IP packets may be forwarded through a user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to one or more network operators' IP services 150. The IP services 150 may include access to the Internet, an intranet, IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0056] Some of the network devices, such as the base stations 105, may include subcomponents, such as an access network entity 140, which may be an example of an access node controller (ANC). Each access network entity 140 may communicate with the UE 115 through one or more other access network transmitting entities 145, which may be referred to as a radio head, a smart radio head, or a transmit / receive point (TRP). Each access network transmitting entity 145 may include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or integrated into a single network device (e.g., the base station 105).

[0057] The wireless communication system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). The 300 MHz to 3 GHz region is commonly referred to as the ultra-high frequency (UHF) region or decimeter band because wavelengths range from approximately 1 decimeter to 1 meter. Although UHF waves may be blocked or redirected by buildings and environmental features, the waves can penetrate structures sufficiently for a macrocell to provide service to UEs 115 located indoors. Transmission of UHF waves may involve smaller antennas and shorter distances (e.g., less than 100 kilometers) compared to transmissions using lower frequencies and longer waves in the shortwave (high frequency (HF)) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0058] The wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may utilize licensed-assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band, such as the 5 GHz Industrial, Scientific, and Medical (ISM) band. When operating in the unlicensed radio frequency spectrum band, devices such as the base station 105 and the UE 115 may utilize carrier sensing for collision detection and avoidance. In some examples, operation in the unlicensed band may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA). Operation in the unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

[0059] The base station 105 or the UE 115 may be equipped with multiple antennas that can be used to utilize techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the base station 105 or the UE 115 may be located in one or more antenna arrays or antenna panels that can support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be collocated in an antenna assembly such as an antenna tower. In some examples, antennas or antenna arrays associated with the base station 105 may be located in various geographic locations. The base station 105 may have an antenna array with several rows and columns of antenna ports that the base station 105 can use to support beamforming of communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted through the antenna ports.

[0060] Beamforming, sometimes referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting or receiving device (e.g., base station 105, UE 115) to shape or steer an antenna beam (e.g., transmit beam, receive beam) along a spatial path between the transmitting and receiving devices. Beamforming may be achieved by combining signals communicated through antenna elements of an antenna array such that some signals propagating at a particular orientation relative to the antenna array experience constructive interference and other signals experience destructive interference. Adjusting signals communicated through antenna elements may include the transmitting or receiving device applying an amplitude offset, a phase offset, or both to signals carried through antenna elements associated with the device. The adjustment associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the antenna array of the transmitting or receiving device, or relative to some other orientation).

[0061] The UE 115 and the base station 105 may support retransmission of data to increase the likelihood of successful reception of the data. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data will be correctly received over the communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the medium access control (MAC) layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device may support same-slot HARQ feedback, in which the device may provide HARQ feedback in a particular slot for data received in a previous symbol in that slot. In other cases, the device may provide HARQ feedback in a subsequent slot or according to some other time interval.

[0062] The wireless communication system 100 may support a sidelink discontinuous reception procedure, in which the UE 115 transitions between an active period (e.g., the UE 115 monitors sidelink communications) and an inactive period (e.g., the UE 115 refrains from monitoring sidelink communications). In some cases, the active period for the UE 115 (e.g., during a discontinuous reception procedure for sidelink communications) may be defined by a timer. That is, the UE 115 may enter an active period in response to starting a timer and transition to an inactive period based on expiration of the timer.

[0063] When performing a discontinuous reception procedure for sidelink communication, the UE 115 may receive control signaling indicating a configuration for the discontinuous reception procedure (e.g., indicating the duration of a timer associated with the UE 115's active period). The UE 115 may then receive a sidelink communication from another UE according to the configuration (e.g., including control information such as sidelink control information (SCI) containing data). The UE 115 may attempt to decode the data in the sidelink communication, and if the UE 115 is unable to decode the data, the UE 115 may receive a retransmission of the data (e.g., in a subsequent sidelink communication). For some types of discontinuous reception procedures, the UE 115 may transmit a feedback message requesting a retransmission of the data and may receive the retransmission in response to the feedback message. In general, the described techniques provide a sidelink discontinuous reception procedure configuration indicating the duration of a timer (e.g., associated with the UE 115's active period) so that the UE 115 is in an active period to receive a retransmission of data from another UE 115 as part of the sidelink discontinuous reception procedure.

[0064] In some cases, the UE 115 may be configured to perform a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure (e.g., sidelink mode 2). Here, the UE 115 may receive control signaling (e.g., SCI) indicating a configuration for the sidelink discontinuous reception procedure associated with the sidelink resource reservation procedure. When receiving sidelink communication during the sidelink discontinuous reception procedure associated with the sidelink resource reservation procedure, the SCI includes reservation information (e.g., reserving resources for feedback messages, reserving resources for data retransmissions). In some examples, the reservation information may be in units of subchannels in the frequency domain and associated with a single slot in the time domain. Additionally or alternatively, the reservation may be for a window related to an amount of logical slots (e.g., a window of 32 logical slots). In some examples, resource reservation may be periodic or aperiodic. In an example of periodic resource reservation, the period may be configured in the control signaling (e.g., the period is between 0 ms and 1000 ms). Additionally, periodic resource reservation may be disabled (eg, by additional configuration information).

[0065] When performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the UE 115 may start a timer in response to sending feedback requesting a retransmission of data received from another UE 115. In addition, the UE 115 may receive a retransmission based on starting the timer. In some cases, the UE 115 may start the timer in response to the expiration of a different timer (e.g., associated with an inactivity period) that is started based on sending feedback requesting a retransmission. In some other cases, the UE 115 may start the timer at a time indicated by a configuration (e.g., associated with the sidelink discontinuous reception procedure).

[0066] In some cases, the UE 115 may be configured to perform a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE 115 in a sidelink communication. Here, the UE 115 may receive control signaling (e.g., SCI-2) indicating a configuration for the sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE 115 in the sidelink communication. When receiving a sidelink communication associated with the sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE 115 in the sidelink communication, the SCI (e.g., included in the sidelink communication) may include a feedback process identifier (e.g., an HARQ process identifier), a network device identifier, a source identifier (e.g., an identifier for the transmitting UE 115), a destination identifier (e.g., an identifier for the receiving UE 115), and optionally, a channel state information reporting trigger (e.g., for unicast sidelink communication). In addition, the SCI may include a shortened identifier (e.g., source identifier, destination identifier), and the data in the sidelink communication (e.g., received via the physical sidelink shared channel (PSSCH)) may include the full identifier. Thus, when UE 115 receives a sidelink communication including an SCI and data, UE 115 may compare the destination identifiers (e.g., the shortened destination identifier in the SCI and the full destination identifier in the data) to determine whether the sidelink communication is intended for UE 115.

[0067] When performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE 115 in a sidelink communication, the UE 115 may start a timer (e.g., associated with an active period) based on receiving a first sidelink communication (e.g., including an identifier associated with the UE) and may subsequently receive a data transmission based on starting the timer. In the first case, the UE 115 may start the timer at a time indicated by a configuration based on the first sidelink communication including an identifier associated with the UE 115. In another case, the UE 115 may start the timer based on receiving the first sidelink communication (e.g., before determining whether the first sidelink communication includes an identifier associated with the UE 115). Here, the UE 115 may optionally reset the timer to zero if the first sidelink communication does not include an identifier associated with the UE 115 (e.g., and will not receive a subsequent data transmission unless other timers place the UE in an active state).

[0068] In some cases, the UE 115 may be configured to perform a sidelink discontinuous reception procedure associated with blind retransmissions. Here, a first UE 115 may transmit a retransmission of sidelink data to another UE 115 without receiving feedback (e.g., HARQ acknowledgment or negative acknowledgment feedback). In some cases, blind retransmissions may be associated with reduced latency for data retransmissions (e.g., when compared to retransmissions sent in response to feedback). When performing a sidelink discontinuous reception procedure associated with blind retransmissions, the UE 115 may start a timer in response to receiving the first sidelink transmission. In some cases, the UE 115 may start the timer if the sidelink transmission includes new data (e.g., instead of retransmitted data). In other cases, the UE 115 may additionally start the timer if the sidelink transmission includes a data retransmission.

[0069] 2 illustrates an example wireless communication system 200 that supports discontinuous reception operation for sidelink communications in accordance with aspects of the present disclosure. In some examples, the wireless communication system 200 may implement aspects of the wireless communication system 100. For example, the wireless communication system 200 may include a UE 215, which may be an example of the UE 115 as described with reference to FIG. 1.

[0070] The wireless communication system 200 may include a UE 215-a and a UE 215-b, which may be communicating over the sidelink using a discontinuous reception procedure. For example, the UE 215-b may transition between an active period (e.g., the UE 215-b is in an active state and monitors resources associated with the sidelink for communications from the UE 215-a) and an inactive period (e.g., the UE 215-b is in an inactive state and refrains from monitoring resources associated with the sidelink for communications from the UE 215-a). In some examples, performing a discontinuous reception procedure for sidelink communications may consume less power when compared to a continuous reception procedure for sidelink communications (e.g., the UE 215-b remains in an active state rather than transitioning to an inactive state).

[0071] The UE 215-b may transition between an active state and an inactive state based on starting a timer (and responding to the expiration of the timer). For example, the UE 215-b may transition to an active state when starting a first timer (e.g., drx-InactivityTimerDuration) and may transition to an inactive state upon expiration of the first timer. In addition, the UE 215-b may transition to an inactive state when starting another timer (e.g., drx-HARQ-RTT-Timer) and may transition to an active state upon expiration of the timer. In some cases, the timer may be configured (e.g., the duration of the timer may be configured) via control signaling 205 received by the UE 215-b.

[0072] The UE 215-a may transmit control signaling 205 to the UE 215-b indicating a configuration for a discontinuous reception procedure for sidelink communications (e.g., between the UEs 215). In some cases, the configuration may indicate a type of discontinuous reception procedure (e.g., a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, a sidelink discontinuous reception procedure associated with receiving an identifier that identifies the UE in the sidelink communications, or a sidelink discontinuous reception procedure associated with blind retransmissions). In addition, the configuration may indicate the duration of one or more timers associated with the discontinuous reception procedure. For example, the configuration may include a duration for a timer associated with an active period of the UE 215-b. In another example, the configuration may include a duration for a timer associated with an inactive period of the UE 215-b. In addition, the configuration may indicate when the UE 215-b should activate (e.g., start) or reset (e.g., stop) a timer.

[0073] Based on transmitting the control signaling 205, the UE 215-a may transmit a sidelink communication 210 to the UE 215-b. The sidelink transmission may include control information (e.g., SCI) and data (e.g., data transmitted via a PSSCH). The UE 215-b may receive and decode the SCI, the data, or both. If the UE 215-b cannot successfully decode the data included in the sidelink communication 210, the UE 215-b may optionally transmit feedback 220 to the UE 215-b requesting a retransmission of the data.

[0074] In some other cases, the UE 215-b does not transmit feedback 220. For example, the UE 215-b may be performing a discontinuous reception procedure associated with blind retransmission. Here, even if the UE 215-b fails to decode the data in the sidelink communication 210, the UE 215-b does not transmit feedback 220 to the UE 215-a. In addition, if the UE 215-b successfully decodes the data in the sidelink communication 210, the UE 215-b does not transmit feedback 220 requesting a retransmission. In addition, if the UE 215-b determines that the data is not intended for the UE 215-b based on the destination identifier in the sidelink communication 210 being different from the UE 215-b's identifier, the UE 215-b does not transmit feedback 220 requesting a retransmission.

[0075] In some cases, the UE 215-a may transmit the retransmission 225 to the UE 215-b (e.g., in another sidelink communication). For example, the UE 215-a may transmit the retransmission 225 in response to receiving feedback 220 requesting the retransmission 225. In another example, the UE 215-a may transmit the retransmission 225 without receiving feedback 220 (e.g., if the UE 215-a is performing a discontinuous reception procedure associated with blind retransmission). In either example, the UE 215-b may be in an active state to receive the retransmission 225 based on starting a timer associated with an active period before receiving the retransmission 225.

[0076] In an example of a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the UE 215-b may start a timer in response to transmitting feedback 220 requesting a retransmission 225. In some cases, the UE 215-b may start a timer in response to the expiration of a different timer (e.g., associated with an inactivity period) that the UE 215-b may start based on transmitting feedback 220. In some other cases, the UE 215-b may start a timer at a time indicated by a configuration (e.g., signaled to the UE 215-b in 205).

[0077] In an example of a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE 215 in a sidelink communication, the UE 215-b may start a timer based on receiving the sidelink communication 210 and may subsequently receive a retransmission 225 based on starting the timer. Here, the retransmission 225 may alternatively include a subsequent data transmission (e.g., instead of a data retransmission 225). In a first case, the UE 215-b may start the timer at a time indicated by a configuration (e.g., signaled in 205) based on the sidelink communication 210 including an identifier associated with the UE 215-b (e.g., the MAC-ID of the UE 215-b). In another case, the UE 215-b may start the timer based on receiving the sidelink communication 210 (e.g., before determining whether the sidelink communication 210 includes an identifier associated with the UE 215-b). Here, the UE 215-b may optionally reset the timer if the sidelink communication 210 does not include an identifier associated with the UE 215-b (e.g., and does not receive the retransmission 225).

[0078] In an example of a sidelink discontinuous reception procedure associated with blind retransmissions, the UE 215-b may start a timer in response to receiving the sidelink communication 210. In one case, the UE 215-b may start the timer if the sidelink communication 210 includes new data (e.g., instead of retransmitted data). In another case, the UE 215-b may additionally start the timer if the sidelink communication 210 includes a data retransmission.

[0079] 3 illustrates an example timing diagram 300 supporting discontinuous reception operation for sidelink communications in accordance with an aspect of the present disclosure. In some cases, the timing diagram 300 may implement aspects of the wireless communication systems 100 and 200 described herein. For example, the sidelink communications 310 and feedback 315 may be examples of transmissions between UEs over the sidelink described with reference to FIGS. 1 and 2. The timing diagram 300 may illustrate an example inactive period timer 320 and an active period timer 325.

[0080] The timing diagram 300 may be an example timing diagram corresponding to a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure. Here, a sidelink communication 310 may be transmitted (e.g., via the sidelink) from a first UE (e.g., to a second UE), while a feedback 315 may be transmitted from the second UE (e.g., to the first UE). In addition, the sidelink communication 310 may include both control information (e.g., SCI) and data (e.g., transmitted via the PSSCH). In some cases, the SCI may include resource reservation information (e.g., reserving resources for the feedback 315, resources for other sidelink communications 310, such as retransmissions).

[0081] In the example timing diagram 300, the second UE may receive an SCI (e.g., in the sidelink communication 310-a) at time T0. In some cases, the second UE may start a timer associated with an active period (e.g., drx-InactivityTimerDuration) at time T0 in response to detecting the SCI in the sidelink communication 310-a. However, in the example timing diagram 300, the second UE may instead start the active period timer 325 based on transmitting feedback 315. For example, the second UE may transmit feedback 315 requesting a retransmission (e.g., of data in the sidelink communication 310-a) and may start the active period timer 325 based on transmitting the feedback 315.

[0082] In one example, the second UE may start the active period timer 325 (e.g., drx-RetransmissionTimer) based on the expiration of the inactive period timer 320 (e.g., drx-HARQ-RTT-Timer). That is, after transmitting the feedback 315, the second UE may start the inactive period timer 320 at time T1. The inactive period timer 320 may span a duration from time T1 to time T2. For example, the second UE may use the inactive period timer 320 to count down a duration from time T1 to time T2. In another example, the second UE may start the inactive period timer 320 at 0 and count up to time T2 (e.g., to a value configured by control signaling indicating a configuration for a discontinuous reception procedure). At time T2, the second UE may start the active period timer 325 in response to the expiration of the inactive period timer 320. Accordingly, at time T2, the second UE may transition from an inactive state to an active state (e.g., may begin monitoring resources to receive retransmissions via sidelink communication 310-b) based on starting the active period timer 325.

[0083] In another example, the second UE may start the active period timer 325 at time T2 based on a configuration (e.g., for a discontinuous reception procedure) indicating time T2. That is, the second UE may not start the inactive period timer 320 at time T1 but may instead start the active period timer at T2 according to the time T2 indicated by the configuration. In some cases, the configuration may indicate time T2 by indicating an amount of slots before the sidelink communication 310-b. Here, the amount of slots associated with starting the active period timer 325 may be pre-configured (e.g., by control signaling indicating a configuration for a discontinuous reception procedure) or may be signaled semi-statically (e.g., within the SCI of the sidelink communication 310). Thus, at time T2, the second UE may transition to the active state based on starting the active period timer 325 (e.g., at the time T2 indicated by the configuration).

[0084] In another example, the second UE may start the active period timer 325 based on either the expiration of the inactive period timer 320 or the configured time for starting the active period timer 325. That is, the second UE may identify a time that occurs later from a first time associated with the expiration of the inactive period timer 320 and a second time associated with the configured time for starting the active period timer 325. Here, the second UE may start the active period timer 325 according to which time occurs later (e.g., from the first time and the second time). In some examples, starting the active period timer 325 at a later time may increase power savings of the second UE when compared to starting the active period timer 325 earlier (e.g., and spending more time in the active state).

[0085] At time T3 (e.g., after starting the active period timer 325), the second UE may receive a second sidelink communication 310-b, which may include a retransmission of data transmitted by the first UE in response to receiving feedback 315 requesting a retransmission.

[0086] 4 illustrates an example timing diagram 400 supporting discontinuous reception operation for sidelink communications in accordance with an aspect of the present disclosure. In some cases, the timing diagram 300 may implement aspects of the wireless communication systems 100 and 200 described herein. For example, the sidelink communications 410 and feedback 415 may be examples of transmissions between UEs over the sidelink described with reference to FIGS. 1 and 2. The timing diagram 400 may also illustrate an example active period timer 420.

[0087] The timing diagram 400 may be an example timing diagram corresponding to a sidelink discontinuous reception procedure associated with receiving an identifier identifying a UE in a sidelink communication. Here, the sidelink communication 410 may be transmitted from a first UE to a second UE (e.g., via the sidelink), while the feedback 415 may be transmitted from the second UE to the first UE. Additionally, the sidelink communication 410 may include both control information (e.g., SCI) and data (e.g., transmitted via the PSSCH).

[0088] In the example timing diagram 400, the second UE may receive an SCI (e.g., in sidelink communication 410-a) at time T0. In some cases, the SCI may include a shortened identifier of the destination UE (e.g., the second UE). For example, the SCI in sidelink communication 410-a may include a shortened version of a MAC identifier associated with the second UE. In addition, the data in sidelink communication 410-a may include a full identifier of the destination UE (e.g., the second UE). For example, the data in sidelink communication 410-a may include a full version of the MAC identifier of the second UE.

[0089] The second UE may send feedback 415 to the first UE based on receiving the sidelink communication 410-a. For example, the feedback 415 may be an acknowledgment or negative acknowledgment message (e.g., HARQ acknowledgment or negative acknowledgment feedback). If the second UE is unable to decode the data in the sidelink communication 410-a, the second UE may send feedback 415 requesting a retransmission (e.g., HARQ NACK feedback). The first UE may then transmit a sidelink communication 410-b including a retransmission of the data in response to the feedback 415. To receive the retransmission in the sidelink communication 410-b, the second UE may transition to an active state based on starting the active period timer 420.

[0090] In some cases, the second UE may start an active period timer 420-a associated with an active period (e.g., drx-InactivityTimerDuration) at time T0 in response to detecting an SCI in the sidelink communication 410-a. In some cases, the second UE may start the active period timer 420-a before decoding the SCI in the sidelink communication 410-a and before determining whether a shortened identifier in the SCI matches the identifier of the second UE. Here, the active period timer 420 may extend from time T0 to after time T3 (e.g., when the first UE transmits a sidelink communication 410-b including a data retransmission).

[0091] In some cases, if the second UE determines that the destination identifier in the sidelink communication 410-a is different from the identifier of the second UE (e.g., the sidelink communication 410-a is intended for a different UE than the second UE), the second UE may voluntarily reset the active period timer 420-a at time T2. That is, if the second UE determines that the sidelink communication 410-a is not intended for the second UE, the second UE may reset the active period timer 420-a and transition from the active state to the inactive state.

[0092] In some other cases, the second UE may start the active period timer 420-b at time T2 in response to determining that the destination identifier in the data of the sidelink communication 410-a is the same as the identifier of the second UE (e.g., the sidelink communication 410-a is intended for the second UE). In some cases, time T2 may be configured in the configuration for the discontinuous reception procedure. That is, the configuration may indicate (e.g., to the second UE) time T2 based on the amount of slots after the UE detects the data in the sidelink communication 410-a or based on the amount of slots after transmitting feedback 415.

[0093] At time T3 (e.g., after starting the active period timer 420), the second UE may receive a second sidelink communication 410-b, which may include a retransmission of data transmitted by the first UE in response to receiving feedback requesting the retransmission 415. In some other cases, the second sidelink communication 410-b may be a subsequent data transmission (e.g., including new data).

[0094] 5 illustrates an example timing diagram 500 supporting discontinuous reception operation for sidelink communications in accordance with an aspect of the present disclosure. In some cases, the timing diagram 500 may implement aspects of the wireless communication systems 100 and 200 described herein. For example, the sidelink communications 510 may be an example of transmissions between UEs over the sidelink described with reference to FIGS. 1 and 2. The timing diagram 500 may illustrate an example active period timer 520.

[0095] The timing diagram 500 may be an example timing diagram corresponding to a sidelink discontinuous reception procedure associated with blind retransmissions. Here, sidelink communications 510 may be transmitted (e.g., via the sidelink) from a first UE to a second UE. Additionally, the sidelink communications 510 may include both control information (e.g., SCI) and data (e.g., transmitted via the PSSCH). In the example of the timing diagram 500, the first UE may transmit blind data retransmissions. For example, sidelink communication 510-a may include new data, while sidelink communication 510-b may include retransmitted data.

[0096] In the example timing diagram 500, the second UE may receive an SCI in a sidelink communication 510-a at time T0. In response to detecting the SCI in the sidelink communication 510-a, the second UE may start an active period timer 520. In some cases, the active period timer 520 may extend the period of time that allows the second UE to detect a subsequent sidelink communication 510-b that includes a blind data retransmission from the first UE.

[0097] In one example, the second UE may start the active period timer 520 when the sidelink communication 510-a includes new data (e.g., instead of retransmitted data). Here, the duration of the active period timer 520 may be greater than a time period associated with a gap between sidelink communications 510 that may include new or retransmitted data. Thus, the second UE may be in an active state to receive both data retransmissions and new data transmissions in subsequent sidelink communications 510. In another example, the second UE may restart the active period timer 520 when the sidelink communication 510-b includes a data retransmission.

[0098] FIG. 6 illustrates an example process flow 600 supporting discontinuous reception operations for sidelink communications according to aspects of the present disclosure. In some examples, the process flow 600 may implement aspects of the wireless communication systems and timing diagrams described herein. For example, the process flow 600 may include a UE 615, which may be an example of a UE described herein. In the following description of the process flow 600, operations between the UE 615 may be transmitted in a different order than shown, or operations performed by the UE 615 may be performed in a different order or at different times. Some operations may also be omitted from the process flow 600, or other operations may be added to the process flow 600. The process flow 600 may illustrate an example of a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure.

[0099] At 605, the UE 615-a may send control signaling to the UE 615-b. The control signaling may indicate a configuration for performing a sidelink discontinuous reception procedure associated with the sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the UE 615-b to receive sidelink retransmissions during the sidelink discontinuous reception procedure.

[0100] At 610, the UE 615-a may transmit a first sidelink communication including data to the UE 615-b based on receiving the control signaling indicating a configuration for performing a sidelink discontinuous reception procedure. In some cases, the first sidelink communication may include control information indicating resources associated with a sidelink resource reservation procedure for receiving a second sidelink communication.

[0101] At 620, the UE 615-b may transmit feedback to the UE 615-a requesting a retransmission of the data based on receiving the first sidelink communication. For example, the UE 615-b may transmit a HARQ requesting a retransmission of the data based on failing to decode the data in the first sidelink communication.

[0102] At 625, in response to transmitting the feedback, the UE 615-b may optionally start a second timer associated with an inactivity period for the UE 615-b to receive sidelink transmissions during the sidelink discontinuous reception procedure.

[0103] At 630, the UE 615-b may start a timer in response to sending feedback based on receiving the first sidelink communication. In some cases (e.g., when the UE 615-b starts a second timer at 625), the UE 615-b may start the timer based on starting the second timer. For example, expiration of the second timer may trigger the starting of the timer at 630. In some other cases, the UE 615-b may identify a time for starting a timer associated with an active period for the UE 615-b to receive sidelink retransmissions from a first time associated with expiration of the second timer and a second time indicated by a configuration for performing a sidelink discontinuous reception procedure corresponding to a time period prior to the resources for receiving the second sidelink communication. Here, the UE 615-b may start the timer based on the identifying. In some other cases, the UE 615-b may start the timer based on a sidelink resource reservation procedure at a time indicated by a configuration for performing a sidelink discontinuous reception procedure. Here, the time indicated by the configuration corresponds to a time period prior to the resources for receiving the second sidelink communication (e.g., at 635).

[0104] At 635, the UE 615-b may receive, based on starting the timer, a second sidelink communication including a retransmission of the data, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0105] FIG. 7 illustrates an example process flow 700 supporting discontinuous reception operations for sidelink communications according to aspects of the present disclosure. In some examples, the process flow 700 may implement aspects of the wireless communication systems and timing diagrams described herein. For example, the process flow 700 may include a UE 715, which may be an example of a UE described herein. In the following description of the process flow 700, operations between the UE 715 may be transmitted in a different order than shown, or operations performed by the UE 715 may be performed in a different order or at different times. Some operations may also be omitted from the process flow 700, or other operations may be added to the process flow 700. The process flow 700 may illustrate an example of a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in sidelink communications.

[0106] At 705, the UE 715-b may receive control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier that identifies the UE in sidelink communications, the configuration indicating a duration of a timer associated with an active period for the UE 715-b to receive sidelink retransmissions.

[0107] At 710, the UE 715-b may receive a first sidelink communication from the UE 715-a, the first sidelink communication including control information including at least a portion of the identifier of the UE 715-a and data including the identifier of the UE 715-b based on receiving control signaling indicating a configuration to perform a sidelink discontinuous reception procedure.

[0108] At 725, the UE 715-b may identify whether the sidelink communication (e.g., received from the UE 715-a at 710) includes an identifier for the UE 715-b. That is, the sidelink communication may include data (e.g., received via a PSSCH) that includes an identifier for the UE 715 intended to be the recipient of the sidelink communication. At 725, the UE 715-b may compare the shortened identifier included in the control information of the sidelink communication received at 710 with the identifier for the UE 715-b. If the shortened identifier does not match the identifier for the UE 715-b, the UE 715-b does not decode the data included in the sidelink communication.

[0109] If the shortened identifier matches the identifier of the UE 715-b, the UE 715-b may additionally compare an identifier included in the data of the sidelink communication with the identifier of the UE 715-b. If the identifier included in the data matches the identifier of the UE 715-b, the UE 715-b may determine that the sidelink communication is intended for the UE 715-b. If the identifier included in the control information or data of the sidelink communication differs from the identifier of the UE 715-b, the UE 715-b may determine that the sidelink communication is not intended for the UE 715-b.

[0110] At 730, the UE 715-b may transmit feedback to the UE 715-a requesting a retransmission of the data based on receiving the first sidelink communication and the data including the identifier of the UE 715-b. That is, if the sidelink communication is intended for the UE 715-b and the UE 715-b determines that it cannot decode the data included in the sidelink communication, the UE 715-b may transmit feedback requesting a retransmission.

[0111] At 735, the UE 715-b may start a timer based on receiving the first sidelink communication. In one example, the UE 715-b may start the timer before identifying whether the sidelink communication includes a UE identifier at 725. That is, the UE 715-b may start the timer based on detecting control information in the sidelink communication. Here, the UE 715-b may send a retransmission request at 730 after starting the timer.

[0112] In another example, the UE 715-b may start a timer after identifying that the sidelink communication includes a UE identifier at 725. For example, the UE 715-b may start a timer based on identifying (e.g., at 725) that the data includes the UE 715-b's identifier and the time indicated by the configuration for performing a sidelink discontinuous reception procedure. In some examples, the time indicated by the configuration corresponds to a first time period after receiving the first sidelink communication, a second time period after transmitting feedback, or a combination thereof.

[0113] At 740, the UE 715-b may optionally reset the timer. That is, if the UE 715-b starts the timer (e.g., at 735) before determining whether the sidelink communication includes the UE identifier at 725, the UE 715-b may optionally reset the timer if the UE 715-b identifies (e.g., at 725) that the sidelink communication does not include the UE 715-b's identifier.

[0114] At 745, the UE 715-b may receive a second sidelink communication including a retransmission of data based on starting the timer at 720 or 735.

[0115] FIG. 8 illustrates an example process flow 800 supporting discontinuous reception operations for sidelink communications according to aspects of the present disclosure. In some examples, the process flow 800 may implement aspects of the wireless communication systems and timing diagrams described herein. For example, the process flow 800 may include a UE 815, which may be an example of a UE described herein. In the following description of the process flow 800, operations between the UE 815 may be transmitted in a different order than shown, or operations performed by the UE 815 may be performed in a different order or at different times. Some operations may also be omitted from the process flow 800, or other operations may be added to the process flow 800. The process flow 800 may illustrate an example of a sidelink discontinuous reception procedure associated with blind retransmissions.

[0116] At 805, the UE 815-b may receive control signaling from the UE 815-a indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communications, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure.

[0117] At 810, the UE 815-b may receive a first sidelink communication including data from the UE 815-a based on receiving the configuration to perform a sidelink discontinuous reception procedure.

[0118] At 820, the UE 815-b may start a timer based on receiving the first sidelink communication. For example, the UE 815-b may determine, based on control information included in the sidelink communication, that data in the first sidelink communication is associated with a new transmission. Here, the UE 815-b may start a timer based on the determination.

[0119] At 825, the UE 815-b may receive a second sidelink communication including a blind retransmission of the data based on starting the timer.

[0120] At 830, the UE 815-b may optionally restart the timer in response to receiving the second sidelink communication including the blind retransmission of the data, i.e., in other cases, the UE 815-b may refrain from restarting the timer after receiving the second sidelink communication based on the second sidelink communication including the blind retransmission of the data.

[0121] 9 shows a block diagram 900 of a device 905 supporting discontinuous reception operation for sidelink communications in accordance with an aspect of the present disclosure. The device 905 may be an example of an aspect of a UE 115 as described herein. The device 905 may include a receiver 910, a transmitter 915, and a communications manager 920. The device 905 may include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0122] The receiver 910 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to discontinuous reception operation for sidelink communications). The information may be passed to other components of the device 905. The receiver 910 may utilize a single antenna or a set of multiple antennas.

[0123] The transmitter 915 may provide a means for transmitting signals generated by other components of the device 905. For example, the transmitter 915 may transmit information such as packets associated with various information channels (e.g., a control channel, a data channel, an information channel related to discontinuous reception operation for sidelink communications), user data, control information, or any combination thereof. In some examples, the transmitter 915 may be collocated with the receiver 910 in a transceiver module. The transmitter 915 may utilize a single antenna or a set of multiple antennas.

[0124] The communications manager 920, the receiver 910, the transmitter 915, or various combinations thereof or components thereof may be examples of means for performing various aspects of discontinuous reception operations for sidelink communications described herein. For example, the communications manager 920, the receiver 910, the transmitter 915, or various combinations thereof or components thereof may support a method for performing one or more of the functions described herein.

[0125] In some examples, the communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry). The hardware may include a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in this disclosure. In some examples, the processor and a memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

[0126] Additionally or alternatively, in some examples, the communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communications management software or firmware). When implemented in code executed by a processor, the functions of the communications manager 920, the receiver 910, the transmitter 915, or various combinations or components thereof may be performed by a general-purpose processor, a DSP, a central processing unit (CPU), an ASIC, an FPGA, or any combination of these or other programmable logic devices (e.g., configured as a means for performing or otherwise supporting the functions described in this disclosure).

[0127] In some examples, the communications manager 920 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using, or possibly cooperating with, the receiver 910, the transmitter 915, or both. For example, the communications manager 920 may receive information from the receiver 910, send information to the transmitter 915, or be integrated with the receiver 910, the transmitter 915, or both to receive information, transmit information, or perform various other operations described herein.

[0128] The communications manager 920 may support wireless communications at the first UE according to examples as disclosed herein. For example, the communications manager 920 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure. The communications manager 920 may be configured as or otherwise support a means for receiving a first sidelink communication including data from a second UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. The communications manager 920 may be configured as or otherwise support a means for transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication. The communications manager 920 may be configured as or otherwise support a means for starting a timer in response to transmitting feedback based on receiving the first sidelink communication. The communications manager 920 may be configured as or otherwise support means for receiving, based on starting a timer, a second sidelink communication including a retransmission of data, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0129] Additionally or alternatively, the communications manager 920 may support wireless communications at the first UE in accordance with examples disclosed herein. For example, the communications manager 920 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in the sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE. The communications manager 920 may be configured as or otherwise support a means for receiving, from the second UE, a first sidelink communication including control information including at least a portion of the identifier of the first UE and data including the identifier of the first UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. The communications manager 920 may be configured as or otherwise support a means for transmitting feedback to the second UE requesting a retransmission of data based on receiving the first sidelink communication and the data including the identifier of the first UE. The communications manager 920 may be configured or otherwise support a means for starting a timer based on receiving the first sidelink communication. The communications manager 920 may be configured or otherwise support a means for receiving a second sidelink communication, including a retransmission of data, based on starting the timer.

[0130] Additionally or alternatively, the communications manager 920 may support wireless communications at the first UE in accordance with examples disclosed herein. For example, the communications manager 920 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communications, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure. The communications manager 920 may be configured as or otherwise support a means for receiving a first sidelink communication including data from a second UE based on receiving the configuration for performing the sidelink discontinuous reception procedure. The communications manager 920 may be configured as or otherwise support a means for starting a timer based on receiving the first sidelink communication. The communications manager 920 may be configured as or otherwise support a means for receiving a second sidelink communication including a blind retransmission of data based on starting the timer.

[0131] By including or configuring a communications manager 920 according to examples as described herein, the device 905 (e.g., a processor controlling or otherwise coupled to the receiver 910, the transmitter 915, the communications manager 920, or a combination thereof) may support techniques for reducing power consumption (e.g., by reducing the amount of time the device 905 is in an active state).

[0132] 10 shows a block diagram 1000 of a device 1005 supporting discontinuous reception operation for sidelink communications in accordance with an aspect of the present disclosure. The device 1005 may be an example of an aspect of the device 905 or UE 115 described herein. The device 1005 may include a receiver 1010, a transmitter 1015, and a communications manager 1020. The device 1005 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0133] The receiver 1010 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., a control channel, a data channel, an information channel related to discontinuous reception procedures for sidelink communications). The information may be passed to other components of the device 1005. The receiver 1010 may utilize a single antenna or a set of multiple antennas.

[0134] The transmitter 1015 may provide a means for transmitting signals generated by other components of the device 1005. For example, the transmitter 1015 may transmit information such as packets associated with various information channels (e.g., a control channel, a data channel, an information channel related to discontinuous reception operation for sidelink communications), user data, control information, or any combination thereof. In some examples, the transmitter 1015 may be collocated with the receiver 1010 in a transceiver module. The transmitter 1015 may utilize a single antenna or a set of multiple antennas.

[0135] The device 1005 or its various components may be examples of means for performing various aspects of discontinuous reception operations for sidelink communications described herein. For example, the communications manager 1020 may include a control signaling manager 1025, a sidelink communications receiver 1030, a feedback manager 1035, a timer manager 1040, or any combination thereof. The communications manager 1020 may be an example of an aspect of the communications manager 920 as described herein. In some examples, the communications manager 1020 or its various components may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the receiver 1010, the transmitter 1015, or both. For example, the communications manager 1020 may receive information from the receiver 1010, send information to the transmitter 1015, or be integrated in combination with the receiver 1010, the transmitter 1015, or both to receive information, transmit information, or perform various other operations as described herein.

[0136] The communications manager 1020 may support wireless communications in the first UE according to examples as disclosed herein. The control signaling manager 1025 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure. The sidelink communications receiver 1030 may be configured as or otherwise support a means for receiving a first sidelink communication including data from a second UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. The feedback manager 1035 may be configured as or otherwise support a means for transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication. The timer manager 1040 may be configured or otherwise support starting a timer in response to sending feedback based on receiving the first sidelink communication. The sidelink communication receiver 1030 may be configured or otherwise support receiving a second sidelink communication including a retransmission of data based on starting a timer, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0137] Additionally or alternatively, the communications manager 1020 may support wireless communications at the first UE according to examples disclosed herein. The control signaling manager 1025 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in the sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE. The sidelink communications receiver 1030 may be configured as or otherwise support a means for receiving, from the second UE, a first sidelink communication including control information including at least a portion of the identifier of the first UE and data including the identifier of the first UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. The feedback manager 1035 may be configured as or otherwise support a means for transmitting feedback to the second UE requesting a retransmission of data based on receiving the first sidelink communication and the data including the identifier of the first UE. The timer manager 1040 may be configured or otherwise support a means for starting a timer based on receiving the first sidelink communication, and the sidelink communication receiver 1030 may be configured or otherwise support a means for receiving a second sidelink communication, including a retransmission of data, based on starting a timer.

[0138] Additionally or alternatively, the communications manager 1020 may support wireless communications at the first UE according to examples disclosed herein. The control signaling manager 1025 may be configured as, or otherwise support, a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communications, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure. The sidelink communications receiver 1030 may be configured as, or otherwise support, a means for receiving a first sidelink communication including data from a second UE based on receiving the configuration for performing the sidelink discontinuous reception procedure. The timer manager 1040 may be configured as, or otherwise support, a means for starting a timer based on receiving the first sidelink communication. The sidelink communications receiver 1030 may be configured as, or otherwise support, a means for receiving a second sidelink communication including a blind retransmission of data based on starting the timer.

[0139] FIG. 11 shows a block diagram 1100 of a communications manager 1120 supporting discontinuous reception operation for sidelink communications in accordance with an aspect of the present disclosure. The communications manager 1120 may be an example of aspects of the communications manager 920, the communications manager 1020, or both described herein. The communications manager 1120 or its various components may be an example of a means for performing various aspects of the discontinuous reception operation for sidelink communications described herein. For example, the communications manager 1120 may include a control signaling manager 1125, a sidelink communications receiver 1130, a feedback manager 1135, a timer manager 1140, a UE identifier manager 1145, a decoding manager 1150, or any combination thereof. Each of these components may be in direct or indirect communication with each other (e.g., via one or more buses).

[0140] The communications manager 1120 may support wireless communications in the first UE according to examples as disclosed herein. The control signaling manager 1125 may be configured as, or otherwise support, a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure related to a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions during the sidelink discontinuous reception procedure. The sidelink communications receiver 1130 may be configured as, or otherwise support, a means for receiving a first sidelink communication including data from a second UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. The feedback manager 1135 may be configured as, or otherwise support, a means for transmitting feedback to the second UE requesting a retransmission of data based on receiving the first sidelink communication. The timer manager 1140 may be configured as, or otherwise support, a means for starting a timer in response to transmitting feedback based on receiving the first sidelink communication. In some examples, the sidelink communication receiver 1130 may be configured as or otherwise support means for receiving a second sidelink communication including a retransmission of data based on starting a timer, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0141] In some examples, the timer manager 1140 may be configured as or otherwise support means for starting, in response to transmitting the feedback, a second timer associated with an inactivity period for receiving sidelink transmissions during a sidelink discontinuous reception procedure for the first UE, wherein starting the timer associated with an activity period for the first UE is based on starting the second timer.

[0142] In some examples, the expiration of the second timer triggers the starting of a timer associated with an active period for the first UE.

[0143] In some examples, the timer manager 1140 may be configured as or otherwise support a means for identifying a time for starting a timer associated with an active period for receiving sidelink retransmissions for the first UE from a first time associated with expiry of the second timer and a second time indicated by the configuration for performing a sidelink discontinuous reception procedure corresponding to a time period prior to the resource for receiving the second sidelink communication, and starting the timer is based on the identifying.

[0144] In some examples, to support starting a timer in response to transmitting feedback, the timer manager 1140 may be configured as or otherwise support starting a timer based on a sidelink resource reservation procedure at a time indicated by a configuration for performing a sidelink discontinuous reception procedure.

[0145] In some examples, the time indicated by the configuration corresponds to a time period prior to the resources for receiving the second sidelink communication.

[0146] In some examples, the first sidelink communication includes control information indicating resources associated with a sidelink resource reservation procedure for receiving the second sidelink communication.

[0147] In some examples, to support sending feedback, the feedback manager 1135 may be configured as or otherwise support a means for transmitting a HARQ requesting a retransmission of data based on a failure to decode the data in the first sidelink communication.

[0148] Additionally or alternatively, the communications manager 1120 may support wireless communications at the first UE in accordance with examples disclosed herein. In some examples, the control signaling manager 1125 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in the sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE. In some examples, the sidelink communications receiver 1130 may be configured as or otherwise support a means for receiving from the second UE a first sidelink communication including control information including at least a portion of the identifier of the first UE and data including the identifier of the first UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. In some examples, the feedback manager 1135 may be configured as or otherwise support a means for transmitting feedback to the second UE requesting a retransmission of data based on receiving the first sidelink communication and the data including the identifier of the first UE. In some examples, the timer manager 1140 may be configured or otherwise support a means for starting a timer based on receiving a first sidelink communication. In some examples, the sidelink communication receiver 1130 may be configured or otherwise support a means for receiving a second sidelink communication, including a retransmission of data, based on starting a timer.

[0149] In some examples, to support starting a timer, the timer manager 1140 may be configured as or otherwise support starting a timer at a time indicated by a configuration for performing a sidelink discontinuous reception procedure based on identifying that the data includes an identifier of the first UE.

[0150] In some examples, the time indicated by the configuration corresponds to a first time period after receiving the first sidelink communication, a second time period after transmitting the feedback, or a combination thereof.

[0151] In some examples, the sidelink communication receiver 1130 may be configured or otherwise support receiving from the second UE a third sidelink communication including second control information including at least a portion of the third UE's second identifier and second data including the third UE's second identifier based on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure. In some examples, the timer manager 1140 may be configured or otherwise support starting a timer in response to detecting the second control information in the third sidelink communication. In some examples, the UE identifier manager 1145 may be configured or otherwise support identifying that the third UE's second identifier is different from the first UE's identifier based on starting the timer and receiving the third sidelink communication. In some examples, the timer manager 1140 may be configured or otherwise support resetting the timer based on identifying that the third UE's second identifier is different from the first UE's identifier.

[0152] In some examples, to support starting a timer, the timer manager 1140 may be configured or otherwise support starting a timer in response to detecting control information in the first sidelink communication, and sending the feedback is based on starting the timer.

[0153] In some examples, the sidelink communication receiver 1130 may be configured or otherwise support receiving, from the second UE, a third sidelink communication including second control information including at least a portion of a second identifier of the third UE based on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure. In some examples, the decoding manager 1150 may be configured or otherwise support receiving, from the second UE, a third sidelink communication including second control information including at least a portion of a second identifier of the third UE based on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure. In some examples, the decoding manager 1150 may be configured or otherwise support refraining from decoding second data included in the third sidelink communication based on the portion of the second identifier of the third UE being different from the portion of the identifier of the first UE.

[0154] In some examples, the identifier that identifies the UE is a MAC address that identifies the UE in sidelink communications.

[0155] Additionally or alternatively, the communications manager 1120 may support wireless communications at the first UE in accordance with examples disclosed herein. In some examples, the control signaling manager 1125 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communications, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure. In some examples, the sidelink communications receiver 1130 may be configured as or otherwise support a means for receiving a first sidelink communication including data from the second UE based on receiving a configuration for performing the sidelink discontinuous reception procedure. In some examples, the timer manager 1140 may be configured as or otherwise support a means for starting a timer based on receiving the first sidelink communication. In some examples, the sidelink communication receiver 1130 may be configured as or otherwise support receiving a second sidelink communication including a blind retransmission of data based on starting a timer.

[0156] In some examples, the timer manager 1140 may be configured with or otherwise support a means for restarting the timer in response to receiving a second sidelink communication including a blind retransmission of data.

[0157] In some examples, the timer manager 1140 may be configured or otherwise support a means for determining, based on control information included in the first sidelink communication, that data in the first sidelink communication is associated with a new transmission, and starting the timer based on that data being associated with the new transmission. In some examples, the timer manager 1140 may be configured or otherwise support a means for refraining from restarting the timer after receiving a second sidelink communication based on the second sidelink communication including a blind retransmission of data.

[0158] FIG. 12 shows a diagram of a system 1200 including a device 1205 supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. The device 1205 may be or include an example of a component of a device 905, a device 1005, or a UE 115 as described herein. The device 1205 may communicate wirelessly with one or more base stations 105, UEs 115, or any combination thereof. The device 1205 may include components for two-way voice and data communication, including components for transmitting and receiving communications, such as a communications manager 1220, an input / output (I / O) controller 1210, a transceiver 1215, an antenna 1225, a memory 1230, code 1235, and a processor 1240. These components may be in electronic communication or may be coupled (e.g., operatively, communicatively, functionally, electronically, electrically) in some cases via one or more buses (e.g., a bus 1245).

[0159] I / O controller 1210 may manage input and output signals for device 1205. I / O controller 1210 may also manage peripheral devices not integrated within device 1205. In some cases, I / O controller 1210 may represent a physical connection or port to an external peripheral device. In some cases, I / O controller 1210 may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another known operating system. Additionally or alternatively, I / O controller 1210 may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, I / O controller 1210 may be implemented as part of a processor, such as processor 1240. In some cases, a user may interact with the device 1205 through the I / O controller 1210 or through hardware components controlled by the I / O controller 1210 .

[0160] In some cases, the device 1205 may include a single antenna 1225. However, in some other cases, the device 1205 may have two or more antennas 1225 that may be capable of simultaneously transmitting or receiving multiple wireless transmissions. The transceiver 1215 may communicate bidirectionally via one or more antennas 1225, a wired link, or a wireless link, as described herein. For example, the transceiver 1215 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 1215 may also include a modem for modulating packets and providing the modulated packets to the one or more antennas 1225 for transmission, and for demodulating packets received from the one or more antennas 1225. The transceiver 1215, or the transceiver 1215 and the one or more antennas 1225, may be an example of the transmitter 915, the transmitter 1015, the receiver 910, the receiver 1010, or any combination or component thereof, as described herein.

[0161] Memory 1230 may include random access memory (RAM) and read-only memory (ROM). Memory 1230 may store computer-readable computer-executable code 1235, including instructions that, when executed by processor 1240, cause device 1205 to perform various functions described herein. Code 1235 may be stored in a non-transitory computer-readable medium, such as system memory or another type of memory. In some cases, code 1235 may not be directly executable by processor 1240, but (e.g., when compiled and executed) may cause a computer to perform functions described herein. In some cases, memory 1230 may include a basic I / O system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices, among other things.

[0162] The processor 1240 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 1240 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated into the processor 1240. The processor 1240 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1230) to cause the device 1205 to perform various functions (e.g., functions or tasks supporting discontinuous reception operations for sidelink communications). For example, the device 1205 or a component of the device 1205 may include the processor 1240 and the memory 1230 coupled to the processor 1240, where the processor 1240 and the memory 1230 are configured to perform various functions described herein.

[0163] The communications manager 1220 may support wireless communications at a first UE according to examples as disclosed herein. For example, the communications manager 1220 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure. The communications manager 1220 may be configured as or otherwise support a means for receiving a first sidelink communication including data from a second UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. The communications manager 1220 may be configured as or otherwise support a means for transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication. The communications manager 1220 may be configured as or otherwise support a means for starting a timer in response to transmitting feedback based on receiving the first sidelink communication. The communications manager 1220 may be configured as or otherwise support means for receiving, based on starting a timer, a second sidelink communication including a retransmission of data, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0164] Additionally or alternatively, the communications manager 1220 may support wireless communications at the first UE according to examples disclosed herein. For example, the communications manager 1220 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in the sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE. The communications manager 1220 may be configured as or otherwise support a means for receiving, from the second UE, a first sidelink communication including control information including at least a portion of the identifier of the first UE and data including the identifier of the first UE based on receiving the control signaling indicating a configuration for performing the sidelink discontinuous reception procedure. The communications manager 1220 may be configured as or otherwise support a means for transmitting feedback to the second UE requesting a retransmission of data based on receiving the first sidelink communication and the data including the identifier of the first UE. The communications manager 1220 may be configured or otherwise support a means for starting a timer based on receiving the first sidelink communication. The communications manager 1220 may be configured or otherwise support a means for receiving a second sidelink communication, including a retransmission of data, based on starting the timer.

[0165] Additionally or alternatively, the communications manager 1220 may support wireless communications at the first UE in accordance with examples disclosed herein. For example, the communications manager 1220 may be configured as or otherwise support a means for receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure related to blind retransmissions for sidelink communications, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure. The communications manager 1220 may be configured as or otherwise support a means for receiving a first sidelink communication including data from a second UE based on receiving the configuration for performing the sidelink discontinuous reception procedure. The communications manager 1220 may be configured as or otherwise support a means for starting a timer based on receiving the first sidelink communication. The communications manager 1220 may be configured as or otherwise support a means for receiving a second sidelink communication including a blind retransmission of data based on starting the timer.

[0166] By including or configuring a communications manager 1220 according to examples described herein, the device 1205 may support techniques for reducing power consumption.

[0167] In some examples, the communications manager 1220 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver 1215, the one or more antennas 1225, or any combination thereof. Although the communications manager 1220 is shown as a separate component, in some examples, one or more functions described with reference to the communications manager 1220 may be supported or performed by the processor 1240, the memory 1230, the code 1235, or any combination thereof. For example, the code 1235 may include instructions executable by the processor 1240 to cause the device 1205 to perform various aspects of discontinuous reception operations for sidelink communications described herein, or the processor 1240 and the memory 1230 may be otherwise configured to perform or support such operations.

[0168] FIG. 13 shows a flowchart illustrating a method 1300 for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. The operations of method 1300 may be performed by a UE or components thereof as described herein. For example, the operations of method 1300 may be performed by a UE 115 as described with reference to FIGS. 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0169] At 1305, the method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with the sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure. The operations of 1305 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1305 may be performed by a control signaling manager 1125 as described with reference to FIG. 11.

[0170] At 1310, the method may include receiving a first sidelink communication from a second UE, the first sidelink communication including data, based on receiving control signaling indicating a configuration to perform a sidelink discontinuous reception procedure. The operations of 1310 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1310 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0171] At 1315, the method may include transmitting feedback to the second UE, based on receiving the first sidelink communication, requesting a retransmission of the data. The operations of 1315 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1315 may be performed by a feedback manager 1135 as described with reference to FIG. 11.

[0172] At 1320, the method may include starting a timer in response to transmitting feedback based on receiving the first sidelink communication. The operations of 1320 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1320 may be performed by a timer manager 1140 as described with reference to FIG. 11.

[0173] At 1325, the method may include receiving, based on starting the timer, a second sidelink communication including a retransmission of the data, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure. The operations of 1325 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1325 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0174] FIG. 14 shows a flowchart illustrating a method 1400 for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. The operations of method 1400 may be performed by a UE or components thereof as described herein. For example, the operations of method 1400 may be performed by the UE 115 as described with reference to FIGS. 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0175] At 1405, the method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with the sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure. The operations of 1405 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1405 may be performed by the control signaling manager 1125 as described with reference to FIG. 11.

[0176] At 1410, the method may include receiving a first sidelink communication from a second UE, the first sidelink communication including data, based on receiving control signaling indicating a configuration to perform a sidelink discontinuous reception procedure. The operations of 1410 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1410 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0177] At 1415, the method may include transmitting feedback to the second UE, based on receiving the first sidelink communication, requesting a retransmission of the data. The operations of 1415 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1415 may be performed by a feedback manager 1135 as described with reference to FIG. 11.

[0178] At 1420, the method may include, in response to transmitting the feedback, starting a second timer associated with an inactivity period for the first UE to receive sidelink transmissions during the sidelink discontinuous reception procedure. The operations of 1420 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1420 may be performed by a timer manager 1140 as described with reference to FIG. 11.

[0179] At 1425, the method may include starting a timer in response to sending feedback based on receiving the first sidelink communication and starting a second timer. The operations of 1425 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1425 may be performed by a timer manager 1140 as described with reference to FIG. 11.

[0180] At 1430, the method may include receiving, based on starting the timer, a second sidelink communication including a retransmission of the data, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure. The operations of 1430 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1430 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0181] FIG. 15 shows a flowchart illustrating a method 1500 for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. The operations of method 1500 may be performed by a UE or components thereof as described herein. For example, the operations of method 1500 may be performed by a UE 115 as described with reference to FIGS. 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0182] At 1505, the method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in the sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE. The operations of 1505 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1505 may be performed by the control signaling manager 1125 as described with reference to FIG. 11.

[0183] At 1510, the method may include receiving a first sidelink communication from a second UE based on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure, the first sidelink communication including control information including at least a portion of an identifier of the first UE and data including the identifier of the first UE. The operations of 1510 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1510 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0184] At 1515, the method may include transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication and the data including the identifier of the first UE. The operations of 1515 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1515 may be performed by a feedback manager 1135 as described with reference to FIG. 11.

[0185] At 1520, the method may include starting a timer based on receiving the first sidelink communication. The operations of 1520 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1520 may be performed by a timer manager 1140 as described with reference to FIG. 11.

[0186] At 1525, the method may include receiving a second sidelink communication including a retransmission of the data based on starting the timer. The operations of 1525 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1525 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0187] FIG. 16 shows a flowchart illustrating a method 1600 for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. The operations of method 1600 may be performed by a UE or components thereof as described herein. For example, the operations of method 1600 may be performed by a UE 115 as described with reference to FIGS. 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0188] At 1605, the method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in the sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE. The operations of 1605 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1605 may be performed by the control signaling manager 1125 as described with reference to FIG. 11.

[0189] At 1610, the method may include receiving a first sidelink communication from a second UE based on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure, the first sidelink communication including control information including at least a portion of an identifier of the first UE and data including the identifier of the first UE. The operations of 1610 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1610 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0190] At 1615, the method may include transmitting feedback to the second UE requesting a retransmission of the data based on receiving the first sidelink communication and the data including the identifier of the first UE. The operations of 1615 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1615 may be performed by a feedback manager 1135 as described with reference to FIG. 11.

[0191] At 1620, the method may include starting a timer at a time indicated by the configuration for performing a sidelink discontinuous reception procedure based on identifying that the data includes an identifier of the first UE. The operations of 1620 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1620 may be performed by a timer manager 1140 as described with reference to FIG. 11.

[0192] At 1625, the method may include receiving a second sidelink communication including a retransmission of the data based on starting the timer. The operations of 1625 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1625 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0193] FIG. 17 shows a flowchart illustrating a method 1700 for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. The operations of method 1700 may be performed by a UE or components thereof as described herein. For example, the operations of method 1700 may be performed by a UE 115 as described with reference to FIGS. 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0194] At 1705, the method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in the sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE. The operations of 1705 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1705 may be performed by the control signaling manager 1125 as described with reference to FIG. 11.

[0195] At 1710, the method may include receiving a first sidelink communication from a second UE based on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure, the first sidelink communication including control information including at least a portion of an identifier of the first UE and data including the identifier of the first UE. The operations of 1710 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1710 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0196] At 1715, the method may include starting a timer in response to detecting the control information in the first sidelink communication. The operations of 1715 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1715 may be performed by a timer manager 1140 as described with reference to FIG. 11.

[0197] At 1720, the method may include transmitting feedback to the second UE requesting a retransmission of the data based on starting a timer and receiving the data including the first sidelink communication and an identifier of the first UE. The operations of 1720 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1720 may be performed by a feedback manager 1135 as described with reference to FIG. 11.

[0198] At 1725, the method may include receiving a second sidelink communication including a retransmission of the data based on starting the timer. The operations of 1725 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1725 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0199] FIG. 18 shows a flowchart illustrating a method 1800 for supporting discontinuous reception operation for sidelink communications according to an aspect of the present disclosure. The operations of method 1800 may be performed by a UE or components thereof as described herein. For example, the operations of method 1800 may be performed by a UE 115 as described with reference to FIGS. 1-12. In some examples, the UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may perform aspects of the described functions using dedicated hardware.

[0200] At 1805, the method may include receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communication, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure. The operations of 1805 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1805 may be performed by the control signaling manager 1125 as described with reference to FIG. 11.

[0201] At 1810, the method may include receiving a first sidelink communication from the second UE, the first sidelink communication including data, based on receiving a configuration for performing a sidelink discontinuous reception procedure. The operations of 1810 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1810 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0202] At 1815, the method may include starting a timer based on receiving the first sidelink communication. The operations of 1815 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1815 may be performed by a timer manager 1140 as described with reference to FIG. 11.

[0203] At 1820, the method may include receiving a second sidelink communication including a blind retransmission of the data based on starting the timer. The operations of 1820 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1820 may be performed by a sidelink communication receiver 1130 as described with reference to FIG. 11.

[0204] The following provides a summary of aspects of the present disclosure.

[0205] Aspect 1: A method for wireless communication in a first UE, the method comprising: receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure; receiving a first sidelink communication from a second UE, the first sidelink communication comprising data, based at least in part on receiving the control signaling indicating the configuration for performing the sidelink discontinuous reception procedure; transmitting feedback to the second UE, based at least in part on receiving the first sidelink communication, requesting a retransmission of the data; starting a timer in response to transmitting the feedback based at least in part on receiving the first sidelink communication; and receiving a second sidelink communication comprising the retransmission of the data, based at least in part on starting the timer, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure.

[0206] Aspect 2: The method of aspect 1, further comprising, in response to transmitting the feedback, starting a second timer associated with an inactivity period for the first UE to receive sidelink transmissions during a sidelink discontinuous reception procedure, wherein starting the timer associated with an activity period for the first UE is based at least in part on starting the second timer.

[0207] Aspect 3: The method of aspect 2, wherein expiration of the second timer triggers starting a timer associated with an active period for the first UE.

[0208] Aspect 4: The method of any one of Aspects 2 to 3, further comprising identifying a time for starting a timer associated with an active period for receiving sidelink retransmissions for the first UE from a first time associated with expiry of a second timer and a second time indicated by the configuration for performing a sidelink discontinuous reception procedure corresponding to a time period prior to the resource for receiving a second sidelink communication, wherein starting the timer is based at least in part on the identifying.

[0209] Aspect 5: The method of any one of Aspects 1 to 4, wherein the step of starting a timer in response to transmitting feedback further comprises starting the timer based at least in part on a sidelink resource reservation procedure at a time indicated by the configuration for performing a sidelink discontinuous reception procedure.

[0210] Aspect 6: The method of aspect 5, wherein the time indicated by the configuration corresponds to a time period prior to the resources for receiving the second sidelink communication.

[0211] Aspect 7: The method of any one of aspects 1 to 6, wherein the first sidelink communication includes control information indicating resources associated with a sidelink resource reservation procedure for receiving the second sidelink communication.

[0212] Aspect 8: The method of any one of aspects 1 to 7, wherein the step of transmitting feedback includes transmitting a HARQ requesting retransmission of the data based at least in part on a failure to decode the data in the first sidelink communication.

[0213] Aspect 9: A method for wireless communication in a first UE, the method comprising: receiving control signaling indicating a configuration to perform a sidelink discontinuous reception procedure associated with receiving an identifier identifying the UE in a sidelink communication, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions for the first UE; receiving from a second UE a first sidelink communication including control information including at least a portion of an identifier of the first UE and data including the identifier of the first UE based at least in part on receiving the control signaling indicating the configuration to perform the sidelink discontinuous reception procedure; transmitting feedback to the second UE requesting a retransmission of the data based at least in part on receiving the first sidelink communication and the data including the identifier of the first UE; starting a timer based at least in part on receiving the first sidelink communication; and receiving a second sidelink communication including the retransmission of the data based at least in part on starting the timer.

[0214] Aspect 10: The method of aspect 9, wherein the step of starting the timer includes starting the timer at a time indicated by the configuration for performing a sidelink discontinuous reception procedure based at least in part on identifying that the data includes an identifier of the first UE.

[0215] Aspect 11: The method of aspect 10, wherein the time indicated by the configuration corresponds to a first time period after receiving a first sidelink communication, a second time period after transmitting feedback, or a combination thereof.

[0216] Aspect 12: The method of any one of Aspects 9 to 11, further comprising: receiving, from the second UE, a third sidelink communication including second control information including at least a portion of a second identifier of the third UE and second data including the second identifier of the third UE, based at least in part on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure; starting a timer in response to detecting the second control information in the third sidelink communication; identifying, based at least in part on starting the timer and receiving the third sidelink communication, that the second identifier of the third UE is different from the identifier of the first UE; and resetting the timer based at least in part on identifying that the second identifier of the third UE is different from the identifier of the first UE.

[0217] Aspect 13: The method of any one of Aspects 9 to 12, wherein the step of starting a timer includes starting the timer in response to detecting control information in the first sidelink communication, and wherein sending the feedback is based at least in part on starting the timer.

[0218] Aspect 14: The method of any one of Aspects 9 to 13, further comprising: receiving, from the second UE, a third sidelink communication including second control information including at least a portion of a second identifier of the third UE, based at least in part on receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure; and refraining from decoding second data included in the third sidelink communication based at least in part on the portion of the second identifier of the third UE being different from the portion of the identifier of the first UE.

[0219] Aspect 15: The method of any one of aspects 9 to 14, wherein the identifier for identifying the UE is a MAC address for identifying the UE in sidelink communication.

[0220] Aspect 16: A method for wireless communication in a first UE, the method comprising: receiving control signaling indicating a configuration for performing a sidelink discontinuous reception procedure associated with blind retransmissions for sidelink communication, the configuration indicating a duration of a timer associated with an active period for the first UE to receive blind retransmissions during the sidelink discontinuous reception procedure; receiving a first sidelink communication from a second UE, the first sidelink communication including data, based at least in part on receiving the configuration for performing the sidelink discontinuous reception procedure; starting a timer based at least in part on receiving the first sidelink communication; and receiving a second sidelink communication including the blind retransmission of the data, based at least in part on starting the timer.

[0221] Aspect 17: The method of aspect 16, further comprising restarting a timer in response to receiving a second sidelink communication including a blind retransmission of data.

[0222] Aspect 18: The method of any one of Aspects 16-17, further comprising: determining, based at least in part on control information included in the first sidelink communication, that data in the first sidelink communication is associated with a new transmission, wherein starting the timer is based at least in part on the data in the first sidelink communication being associated with the new transmission; and refraining from restarting the timer after receiving a second sidelink communication based at least in part on a second sidelink communication including a blind retransmission of the data.

[0223] Aspect 19: An apparatus for wireless communication in a first UE, the apparatus including: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform any of the methods of aspects 1 to 8.

[0224] Aspect 20: An apparatus for wireless communication in a first UE, the apparatus comprising at least one means for performing the method of any of aspects 1-8.

[0225] Aspect 21: A non-transitory computer-readable medium storing code for wireless communication in a first UE, the code comprising instructions executable by a processor to perform the method of any of aspects 1-8.

[0226] Aspect 22: An apparatus for wireless communication in a first UE, the apparatus including: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform any of the methods of aspects 9 to 15.

[0227] Aspect 23: An apparatus for wireless communication in a first UE, comprising at least one means for performing the method of any of aspects 9-15.

[0228] Aspect 24: A non-transitory computer-readable medium storing code for wireless communication in a first UE, the code comprising instructions executable by a processor to perform the method of any of aspects 9-15.

[0229] Aspect 25: An apparatus for wireless communication in a first UE, the apparatus including: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform any of the methods of aspects 16-18.

[0230] Aspect 26: An apparatus for wireless communication in a first UE, the apparatus comprising at least one means for performing the method of any of aspects 16-18.

[0231] Aspect 27: A non-transitory computer-readable medium storing code for wireless communication in a first UE, the code comprising instructions executable by a processor to perform the method of any of aspects 16-18.

[0232] It should be noted that the methods described herein describe possible implementations, that the operations and steps may be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects from two or more of these methods may be combined.

[0233] Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described as examples, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used throughout much of the description, the techniques described herein may be applicable to networks other than LTE, LTE-A, LTE-A Pro, or NR. For example, the described techniques may be applicable to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0234] The information and signals described herein may be represented using any of a wide variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0235] The various example blocks and components described in connection with the disclosure herein may be implemented or performed using a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0236] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features implementing the functions may also be physically located in various locations, including being distributed so that portions of the functions are implemented in different physical locations.

[0237] Computer-readable media includes both non-transitory computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. Non-transitory storage media may be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of computer-readable media. As used herein, disk and disc include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media.

[0238] As used herein, including in the claims, "or" as used in a list of items (e.g., a list of items preceded by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such as, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, the phrase "based on" as used herein should not be construed as referring to a closed set of conditions. For example, an example step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, the phrase "based on" as used herein should be construed similarly to the phrase "based at least in part on."

[0239] The terms "determine" or "determining" encompass a wide variety of actions, and thus "determining" can include calculating, computing, processing, deriving, investigating, looking up (e.g., by looking up in a table, database, or another data structure), ascertaining, etc. Also, "determining" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. Also, "determining" can include resolving, selecting, choosing, establishing, and other such similar actions.

[0240] In the accompanying figures, similar components or features may have the same reference label. Furthermore, various components of the same type may be distinguished by following the reference label with a dash and a second label that distinguishes among the similar components. If only a first reference label is used herein, the description is applicable to any of the similar components having the same first reference label, regardless of a second reference label, or other subsequent reference label.

[0241] The description set forth herein with reference to the accompanying drawings describes exemplary configurations and does not necessarily represent every example that may be implemented or fall within the scope of the claims. As used herein, the term "exemplary" means "serving as an example, instance, or illustration," and does not mean "preferred" or "advantageous over other examples." The detailed description includes specific details for the purpose of providing an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0242] The description herein is provided to enable any person skilled in the art to make or use the disclosure. Various modifications of the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. [Explanation of symbols]

[0243] 100 Wireless Communication System 105 Base station 110 Coverage Area 115 User Equipment (UE) 120 backhaul links 125 communication links 130 Core Network 135 Device-to-Device (D2D) Communication Links 140 Access Network Entity 145 Access Network Transmission Entity 150 IP Services 200 Wireless Communication Systems 205 Control Signaling 210 Sidelink Communications 215 UE 215-a UE 215-b UE 220 Feedback 225 retransmission 300 Timing Diagram 310 Sidelink Communications 310-a Sidelink Communications 310-b Sidelink Communications 315 Feedback 320 Inactivity Period Timer 325 Active Period Timer 400 Timing Diagram 410 Sidelink Communications 410-a Sidelink Communications 410-b Sidelink Communications 415 Feedback 420 Active Period Timer 420-a Active Period Timer 420-b Active Period Timer 500 Timing Diagram 510 Sidelink Communications 510-a Sidelink Communications 510-b Sidelink Communications 520 Active Period Timer 600 Process Flow 615 UE 615-a UE 615-b UE 700 Process Flow 715 UE 715-a UE 715-b UE 800 Process Flow 815 UE 815-a UE 815-b UE 900 Block Diagram 905 devices 910 Receiver 915 Transmitter 920 Communications Manager 1000 Block Diagram 1005 devices 1010 receiver 1015 Transmitter 1020 Communications Manager 1025 Control Signaling Manager 1030 Sidelink communication receiver 1035 Feedback Manager 1040 Timer Manager 1100 Block Diagram 1120 Communications Manager 1125 Control Signaling Manager 1130 Sidelink communication receiver 1135 Feedback Manager 1140 Timer Manager 1145 UE Identifier Manager 1150 Decryption Manager 1200 System 1205 devices 1210 Input / Output (I / O) Controller 1215 Transceiver 1220 Communications Manager 1225 Antenna 1230 memory 1235 Code 1240 processor

Claims

1. 1. A method for wireless communication in a first user equipment (UE), comprising: receiving first sidelink control information indicating a configuration for performing a sidelink discontinuous reception procedure associated to a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated to an active period for the first UE to receive sidelink retransmissions during the sidelink discontinuous reception procedure; receiving second sidelink control information indicating an explicit indication of a start-up time of the timer, the explicit indication of the start-up time including an explicit indication of an amount of slots starting from a first slot of resources associated to a second sidelink communication and extending before the first slot of resources associated to the second sidelink communication; receiving a first sidelink communication from a second UE, the first sidelink communication comprising data, based at least in part on receiving the first sidelink control information indicating the configuration to perform the sidelink discontinuous reception procedure; and transmitting, based at least in part on receiving the first sidelink communication, feedback to the second UE requesting a retransmission of the data; and in response to transmitting the feedback based at least in part on an explicit indication of the wake-up time, starting the timer at the wake-up time, wherein the second sidelink communication includes a retransmission of the data; and receiving, based at least in part on starting the timer, the second sidelink communication, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure; and A method comprising:

2. The method described in claim 1, wherein the wake-up time is indicated by the configuration for performing the sidelink discontinuous reception procedure and is based at least in part on the sidelink resource reservation procedure.

3. The method described in claim 2, wherein the activation time is indicated by second sidelink control information associated with sidelink communication, and the second sidelink control information is different from the first sidelink control information.

4. 2. The method of claim 1, wherein the first sidelink communication includes control information indicating the resources associated with the sidelink resource reservation procedure for receiving the second sidelink communication.

5. the step of sending feedback comprises:

10. The method of claim 1, comprising transmitting a hybrid automatic repeat request to request the retransmission of the data based at least in part on a failure to decode the data in the first sidelink communication.

6. 1. An apparatus for wireless communication in a first user equipment (UE), comprising: a processor; a memory coupled to the processor; instructions stored in the memory, the instructions causing the device to: receiving first sidelink control information indicating a configuration for performing a sidelink discontinuous reception procedure associated with a sidelink resource reservation procedure, the configuration indicating a duration of a timer associated with an active period for receiving sidelink retransmissions during the sidelink discontinuous reception procedure; and receiving second sidelink control information indicating an explicit indication of a start-up time of the timer, the explicit indication of the start-up time including an explicit indication of an amount of slots starting from a first slot of resources associated with a second sidelink communication and extending before the first slot of resources associated with the second sidelink communication; receiving a first sidelink communication from a second UE, the first sidelink communication comprising data, based at least in part on receiving the first sidelink control information indicating the configuration to perform the sidelink discontinuous reception procedure; and transmitting, based at least in part on receiving the first sidelink communication, feedback to the second UE requesting a retransmission of the data; and initiating the timer at the wake-up time in response to transmitting the feedback based at least in part on the explicit indication of the wake-up time, wherein the second sidelink communication includes a retransmission of the data; and receiving, based at least in part on starting the timer, the second sidelink communication, the second sidelink communication being received via resources associated with the sidelink resource reservation procedure; and an apparatus executable by the processor to cause the apparatus to perform 7. The device of claim 6, wherein the wake-up time is indicated by the configuration for performing the sidelink discontinuous reception procedure and is based at least in part on the sidelink resource reservation procedure.

8. The device of claim 7, wherein the wake-up time is indicated by second sidelink control information associated with sidelink communication, the second sidelink control information being different from the first sidelink control information.

9. 7. The apparatus of claim 6, wherein the first sidelink communication includes control information indicating the resources associated with the sidelink resource reservation procedure for receiving the second sidelink communication.

10. The instructions for transmitting the feedback may include:

7. The apparatus of claim 6, wherein the apparatus is executable by the processor to cause transmitting a hybrid automatic repeat request to request the retransmission of the data based at least in part on a failure to decode the data in the first sidelink communication.

11. A computer-readable storage medium having instructions for wireless communication, which, when executed by a processor of a first user equipment (UE), causes the first UE to perform a method described in any one of claims 1 to 5.

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