CN117223340A - Discontinuous reception based on direct frame number in side link communication - Google Patents

Abstract

An efficient approach is disclosed for a User Equipment (UE) to perform side link communication with another UE in Discontinuous Reception (DRX) mode. For example, the UE may determine a Direct Frame Number (DFN) timing and configure a side link DRX mode using one or more side link DRX parameters based on the DFN timing. The UE may perform side link communication with the second UE during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

Description

Discontinuous reception based on direct frame number in side link communication

Cross Reference to Related Applications

This patent application claims priority from pending non-provisional application S/n.17/572,128 filed by the U.S. patent and trademark office at 10 of 2022, and provisional application S/n.63/173,912 filed by the U.S. patent and trademark office at 12 of 2021, both of which are assigned to the assignee of the present application and are hereby expressly incorporated by reference as if fully set forth below and for all applicable purposes.

Technical Field

The techniques discussed below relate generally to wireless communication systems and, more particularly, to performing side link communication in a Discontinuous Reception (DRX) mode using DRX parameter(s) based on a direct frame number.

Introduction to the invention

Wireless communication between devices may be facilitated through various network configurations. In one configuration, a cellular network may enable wireless communication devices (e.g., user Equipment (UE)) to communicate with each other through signaling with nearby base stations or cells. Another wireless communication network configuration is a device-to-device (D2D) network in which wireless communication devices may signal each other directly, rather than via intervening base stations or cells. For example, the D2D communication network may utilize side link signaling to facilitate direct communication between wireless communication devices. In some sidelink network configurations, the wireless communication device may further communicate in a cellular network, typically under control of a base station. Thus, the wireless communication devices may be configured for uplink and downlink signaling via the base station, and further for side link signaling directly between the wireless communication devices without transmission through the base station. In wireless communication systems, such as those specified under the 5G New Radio (NR) standard, D2D communication between UEs may occur via side link communication.

Brief summary of some examples

The following presents a simplified summary of one or more aspects of the disclosure in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended to neither identify key or critical elements of all aspects of the disclosure nor delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a form as a prelude to the more detailed description that is presented later.

Discontinuous Reception (DRX) mode may be utilized by a User Equipment (UE) to turn on the UE for only a certain on duration per DRX cycle in DRX mode. The DRX mode may be defined by at least an on duration for turning on the UE during the DRX cycle and an offset from a reference time for starting the DRX mode. For communication between the UE and the base station, the offset may refer to a reference time associated with a System Frame Number (SFN) timing. However, in side-link communications between UEs, some UEs may not have SFNs and some UEs may have different SFN timings. Thus, relying on SFN timing to perform side link communication between UEs in DRX mode may result in the on durations of DRX cycles in different UEs not overlapping each other and thus may result in difficulties in performing side link communication. According to some aspects of the present disclosure, a UE may configure a side link DRX mode using a Direct Frame Number (DFN) timing-based DRX parameter, and then perform side link communication in the side link DRX mode.

In one example, a method of wireless communication implemented by a UE is disclosed. The method comprises the following steps: determining a DFN timing; configuring a side link DRX mode using one or more side link DRX parameters based on the DFN timing; and performing side link communication with the second UE during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

In another example, a UE for wireless communication is disclosed. The UE includes at least one processor, a transceiver communicatively coupled to the at least one processor, and a memory communicatively coupled to the at least one processor. The at least one processor may be configured to: determining a DFN timing; configuring a side link DRX mode using one or more side link DRX parameters based on the DFN timing; and performing side link communication with the second UE during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

In another example, a non-transitory computer-readable storage medium having instructions thereon for a UE may be disclosed. The instructions, when executed by the processing circuitry, cause the processing circuitry to: determining a DFN timing; configuring a side link DRX mode using one or more side link DRX parameters based on the DFN timing; and performing side link communication with the second UE during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

In a further example, a UE for wireless communication may be disclosed. The UE comprises: means for determining DFN timing; means for configuring a side link DRX mode using one or more side link DRX parameters based on the DFN timing; and means for performing side link communication with the second UE during an on-duration of a side link DRX cycle in the side link DRX mode in accordance with the one or more side link DRX parameters.

In one example, a method of wireless communication by a base station is disclosed. The method comprises the following steps: determining a DFN indicator; and transmitting the DFN indicator to the first UE to cause the first UE to configure a sidelink DRX mode using one or more sidelink DRX parameters based on a DFN timing based on the DFN indicator, wherein sidelink communication between the first UE and the second UE is performed during an on-duration of a sidelink DRX cycle in the sidelink DRX mode according to the one or more sidelink DRX parameters.

In another example, a base station for wireless communication is disclosed. The base station includes at least one processor, a transceiver communicatively coupled to the at least one processor, and a memory communicatively coupled to the at least one processor. The at least one processor may be configured to: determining a DFN indicator; and transmitting the DFN indicator to the first UE to cause the first UE to configure a sidelink DRX mode using one or more sidelink DRX parameters based on a DFN timing based on the DFN indicator, wherein sidelink communication between the first UE and the second UE is performed during an on-duration of a sidelink DRX cycle in the sidelink DRX mode according to the one or more sidelink DRX parameters.

In another example, a non-transitory processor-readable storage medium having instructions thereon for a base station may be disclosed. The instructions, when executed by the processing circuitry, cause the processing circuitry to: determining a DFN indicator; and transmitting the DFN indicator to the first UE to cause the first UE to configure a sidelink DRX mode using one or more sidelink DRX parameters based on a DFN timing based on the DFN indicator, wherein sidelink communication between the first UE and the second UE is performed during an on-duration of a sidelink DRX cycle in the sidelink DRX mode according to the one or more sidelink DRX parameters.

In a further example, a base station for wireless communication can be disclosed. The base station includes: means for determining a DFN indicator; and means for transmitting the DFN indicator to the first UE to cause the first UE to configure a side link DRX mode using one or more side link DRX parameters based on a DFN timing based on the DFN indicator, wherein side link communication between the first UE and the second UE is performed during an on duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

These and other aspects of the present disclosure will be more fully understood upon review of the following detailed description. Other aspects, features and embodiments will become apparent to those ordinarily skilled in the art upon review of the following description of specific exemplary embodiments in conjunction with the accompanying figures. While various features may be discussed below with respect to certain embodiments and figures, all embodiments may include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more such features may also be used in accordance with the various embodiments discussed herein. In a similar manner, although exemplary embodiments may be discussed below as device, system, or method embodiments, it should be appreciated that such exemplary embodiments may be implemented in a variety of devices, systems, and methods.

Brief Description of Drawings

Fig. 1 is a schematic illustration of a wireless communication system in accordance with some aspects.

Fig. 2 is a conceptual illustration of an example of a radio access network according to some aspects.

Fig. 3 is a schematic illustration of an organization of radio resources in an air interface utilizing Orthogonal Frequency Division Multiplexing (OFDM), in accordance with some embodiments.

Fig. 4 illustrates an example of a wireless communication network configured to support D2D or side link communications.

Fig. 5A and 5B are diagrams illustrating examples of side link slot structures according to some aspects.

Fig. 6 is a diagram illustrating an example of a side-chain slot structure with feedback resources, according to some aspects.

Fig. 7A and 7B are example diagrams illustrating timing of two DRX modes by different UEs, according to some aspects.

Fig. 8 is an example diagram illustrating interactions between UEs and possible interactions of UEs with respective base stations, according to some aspects.

Fig. 9A is an example diagram illustrating DFN timing-based direct frames (the DFN timing being determined based on SFN timing), system frames, and GNSS-based direct frames when a base station is synchronized to GNSS time, according to some aspects.

Fig. 9B is an example diagram illustrating DFN timing-based direct frames (the DFN timing being determined based on SFN timing), system frames, and GNSS-based direct frames when a base station is not synchronized to GNSS time, according to some aspects.

Fig. 10A, 10B, and 10C are example diagrams illustrating three DRX modes based on three DFN timings, according to some aspects.

Fig. 11A is an example diagram illustrating DFN timing-based direct frames (the DFN timing being determined based on SFN timing), system frames, and GNSS-based direct frames when a base station is not synchronized to GNSS time, according to some aspects.

Fig. 11B is an example diagram illustrating DFN timing-based direct frames (the DFN timing being determined based on SFN timing), system frames, and GNSS-based direct frames when a base station is not synchronized to GNSS time, according to some aspects.

Fig. 12 is an example flow diagram illustrating interactions between a first UE, a second UE, and a base station in accordance with some aspects.

Fig. 13 is a block diagram conceptually illustrating an example of a hardware implementation for a user equipment, according to some aspects.

Fig. 14 is a flow chart illustrating an exemplary process for wireless communication in accordance with some aspects.

Fig. 15 is a flow chart illustrating an exemplary process for wireless communication in accordance with some aspects.

Fig. 16 is a block diagram conceptually illustrating an example of a hardware implementation for a base station, according to some aspects.

Fig. 17 is a flow chart illustrating an exemplary process for wireless communication in accordance with some aspects of the present disclosure.

Fig. 18 is a flow diagram illustrating an exemplary process for wireless communication in accordance with some aspects.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. It will be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

While aspects and embodiments are described in this disclosure by way of illustration of some examples, those skilled in the art will appreciate that additional implementations and use cases may be produced in many different arrangements and scenarios. The innovations described herein may be implemented across many different platform types, devices, systems, shapes, sizes, packaging arrangements. For example, embodiments and/or uses may be produced via integrated chip embodiments and other non-module component based devices (e.g., end user devices, vehicles, communication devices, computing devices, industrial equipment, retail/shopping devices, medical devices, AI-enabled devices, etc.). While some examples may or may not be specific to each use case or application, the broad applicability of the described innovations may occur. Implementations may range from chip-level or module components to non-module, non-chip-level implementations, and further to aggregated, distributed or Original Equipment Manufacturer (OEM) devices or systems incorporating one or more aspects of the described innovations. In some practical environments, devices incorporating the described aspects and features may also necessarily include additional components and features for implementing and practicing the claimed and described embodiments. For example, the transmission and reception of wireless signals must include several components (e.g., hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders/summers, etc.) for analog and digital purposes. The innovations described herein are intended to be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, end user equipment, and the like, of various sizes, shapes, and configurations.

The various concepts presented throughout this disclosure may be implemented across a wide variety of telecommunication systems, network architectures, and communication standards. Referring now to fig. 1, various aspects of the present disclosure are illustrated with reference to a wireless communication system 100 by way of illustrative example and not limitation. The wireless communication system 100 includes three interaction domains: a core network 102, a Radio Access Network (RAN) 104, and a User Equipment (UE) 106. By way of the wireless communication system 100, the UE 106 may be enabled to perform data communications with an external data network 110, such as, but not limited to, the internet.

RAN 104 may implement any suitable one or more wireless communication technologies to provide radio access to UEs 106. As one example, RAN 104 may operate in accordance with the third generation partnership project (3 GPP) New Radio (NR) specification (commonly referred to as 5G). As another example, the RAN 104 may operate under a mix of 5G NR and evolved universal terrestrial radio access network (eUTRAN) standards (commonly referred to as LTE). The 3GPP refers to this hybrid RAN as the next generation RAN, or NG-RAN. Of course, many other examples may be utilized within the scope of the present disclosure.

As illustrated, the RAN 104 includes a plurality of base stations 108. Broadly, a base station is a network element in a radio access network responsible for radio transmission and reception to or from a UE in one or more cells. In different technologies, standards, or contexts, a base station may be referred to variously by those skilled in the art as a Base Transceiver Station (BTS), a radio base station, a radio transceiver, a transceiver function, a Basic Service Set (BSS), an Extended Service Set (ESS), an Access Point (AP), a Node B (NB), a e B node (eNB), a g B node (gNB), a Transmission Reception Point (TRP), or some other suitable terminology. In some examples, a base station may include two or more TRPs that may be co-located or non-co-located. Each TRP may communicate on the same or different carrier frequencies within the same or different frequency bands.

The radio access network 104 is further illustrated as supporting wireless communications for a plurality of mobile devices. A mobile device may be referred to as a User Equipment (UE) in the 3GPP standards, but may also be referred to by those skilled in the art as a Mobile Station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless communication device, a remote device, a mobile subscriber station, an Access Terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. The UE may be a device (e.g., a mobile device) that provides access to network services to a user.

Within this document, a "mobile" device need not necessarily have mobility capability, and may be stationary. The term mobile device or mobile equipment refers broadly to a wide variety of devices and technologies. The UE may include several hardware structural components sized, shaped, and arranged to facilitate communication; such components may include antennas, antenna arrays, RF chains, amplifiers, one or more processors, and so forth, electrically coupled to each other. For example, some non-limiting examples of mobile devices include mobile equipment, cellular (cell) phones, smart phones, session Initiation Protocol (SIP) phones, laptops, personal Computers (PCs), notebooks, netbooks, smartbooks, tablet devices, personal Digital Assistants (PDAs), and a wide variety of embedded systems, e.g., corresponding to the "internet of things" (IoT). Additionally, the mobile apparatus may be an automobile or other transportation vehicle, a remote sensor or actuator, a robot or robotic device, a satellite radio, a Global Positioning System (GPS) device, a remote control device, consumer and/or wearable devices (such as glasses), a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player), a camera, a game console, and the like. The mobile device may additionally be a digital home or smart home appliance such as a home audio, video and/or multimedia appliance, vending machine, smart lighting device, home security system, smart meter, etc. Additionally, the mobile device may be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device (e.g., smart grid) that controls power, lighting, water, etc.; industrial automation and enterprise equipment; a logistics controller; agricultural equipment; vehicles, etc. Still further, the mobile device may provide networked medical or telemedicine support, such as remote healthcare. The remote healthcare device may include a remote healthcare monitoring device and a remote healthcare supervising device, whose communications may be given priority or prioritized access over other types of information, for example, in the form of prioritized access to critical service data transmissions and/or associated QoS to critical service data transmissions.

Wireless communication between RAN 104 and UE 106 may be described as utilizing an air interface. Transmissions from a base station (e.g., base station 108) to one or more UEs (e.g., UE 106) over an air interface may be referred to as Downlink (DL) transmissions. According to certain aspects of the present disclosure, the term downlink may refer to a point-to-multipoint transmission originating at a scheduling entity (described further below; e.g., base station 108). Another way to describe this scheme may be to use the term broadcast channel multiplexing. The transmission from a UE (e.g., UE 106) to a base station (e.g., base station 108) may be referred to as an Uplink (UL) transmission. According to further aspects of the present disclosure, the term uplink may refer to point-to-point transmissions originating at a scheduled entity (described further below; e.g., UE 106).

In some examples, access to the air interface may be scheduled, where a scheduling entity (e.g., base station 108) allocates resources for communication among some or all devices and equipment within its service area or cell. Within this disclosure, a scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more scheduled entities, as discussed further below. That is, for scheduled communications, the UE 106 (which may be a scheduled entity) may utilize resources allocated by the scheduling entity 108.

The base station 108 is not the only entity that can be used as a scheduling entity. That is, in some examples, a UE may act as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs).

As illustrated in fig. 1, the scheduling entity 108 may broadcast downlink traffic 112 to one or more scheduled entities 106. Broadly, scheduling entity 108 is a node or device responsible for scheduling traffic (including downlink traffic 112 and, in some examples, uplink traffic 116 from one or more scheduled entities 106 to scheduling entity 108) in a wireless communication network. In another aspect, the scheduled entity 106 is a node or device that receives downlink control information 114 (including, but not limited to, scheduling information (e.g., grants), synchronization or timing information), or other control information, from another entity in the wireless communication network, such as scheduling entity 108.

In general, the base station 108 may include a backhaul interface for communicating with a backhaul portion 120 of a wireless communication system. Backhaul 120 may provide a link between base station 108 and core network 102. Further, in some examples, the backhaul network may provide interconnection between respective base stations 108. Various types of backhaul interfaces may be employed, such as direct physical connections using any suitable transport network, virtual networks, and so forth.

The core network 102 may be part of the wireless communication system 100 and may be independent of the radio access technology used in the RAN 104. In some examples, the core network 102 may be configured according to a 5G standard (e.g., 5 GC). In other examples, core network 102 may be configured according to a 4G Evolved Packet Core (EPC) or any other suitable standard or configuration.

Referring now to fig. 2, a schematic illustration of a RAN 200 is provided by way of example and not limitation. In some examples, RAN 200 may be the same as RAN 104 described above and illustrated in fig. 1. The geographical area covered by the RAN 200 may be divided into cellular areas (cells) that may be uniquely identified by a User Equipment (UE) based on an identification broadcast from one access point or base station. Fig. 2 illustrates macro cells 202, 204, and 206, and small cell 208, each of which may include one or more sectors (not shown). A sector is a sub-region of a cell. All sectors within a cell are served by the same base station. The radio links within a sector may be identified by a single logical identification belonging to the sector. In a sectorized cell, multiple sectors within the cell may be formed by groups of antennas, with each antenna being responsible for communication with UEs in a portion of the cell.

In fig. 2, two base stations 210 and 212 are shown in cells 202 and 204; and a third base station 214 is shown controlling a Remote Radio Head (RRH) 216 in the cell 206. That is, the base station may have an integrated antenna, or may be connected to an antenna or RRH by a feeder cable. In the illustrated example, the cells 202, 204, and 126 may be referred to as macro cells because the base stations 210, 212, and 214 support cells having a large size. Further, base station 218 is shown in small cell 208 (e.g., a micro cell, pico cell, femto cell, home base station, home node B, home evolved node B, etc.), small cell 208 may overlap with one or more macro cells. In this example, cell 208 may be referred to as a small cell because base station 218 supports cells having a relatively small size. Cell sizing may be done according to system design and component constraints.

It will be appreciated that the radio access network 200 may include any number of wireless base stations and cells. Furthermore, relay nodes may be deployed to extend the size or coverage area of a given cell. The base stations 210, 212, 214, 218 provide wireless access points to the core network for any number of mobile devices. In some examples, base stations 210, 212, 214, and/or 218 may be the same as base station/scheduling entity 108 described above and illustrated in fig. 1.

Fig. 2 further includes a mobile device 220 that may be configured to function as a base station. That is, in some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station (such as mobile device 220).

Within RAN 200, cells may include UEs that may be in communication with one or more sectors of each cell. Further, each base station 210, 212, 214, 218, and 220 may be configured to provide an access point to the core network 102 (see fig. 1) for all UEs in the respective cell. For example, UEs 222 and 224 may be in communication with base station 210; UEs 226 and 228 may be in communication with base station 212; UEs 230 and 232 may be in communication with base station 214 via RRH 216; UE 234 may be in communication with base station 218; and UE 236 may be in communication with mobile base station 220. In some examples, the UEs 222, 224, 226, 228, 230, 232, 234, 236, 238, 240, and/or 242 may be the same as the UE/scheduled entity 106 described above and illustrated in fig. 1.

In some examples, a mobile network node (e.g., mobile device 220) may be configured to function as a UE. For example, mobile device 220 may operate within cell 202 by communicating with base station 210.

The base station is not the only entity that can be used as a scheduling entity. That is, in some examples, a UE may act as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs). For example, two or more UEs (e.g., UEs 238, 240, and 242) may communicate with each other using side link signals 237 without relaying the communication through a base station. In some examples, UEs 238, 240, and 242 may each act as a scheduling entity or transmitting side link device and/or a scheduled entity or receiver side link device to schedule resources and communicate side link signals 237 therebetween without relying on scheduling or control information from a base station. In other examples, two or more UEs (e.g., UEs 226 and 228) within the coverage area of a base station (e.g., base station 212) may also communicate side link signal 227 over a direct link (side link) without communicating the communication through base station 212. In this example, base station 212 may allocate resources to UEs 226 and 228 for side link communication. In either case, such side link signaling 227 and 237 may be implemented in a peer-to-peer (P2P) network, a device-to-device (D2D) network, a vehicle-to-vehicle (V2V) network, a vehicle networking (V2X), a mesh network, or other suitable direct link network.

In some examples, a D2D relay framework may be included within the cellular network to facilitate relay of communications to/from base station 212 via D2D links (e.g., side links 227 or 237). For example, one or more UEs (e.g., UE 228) within the coverage area of base station 212 may operate as relay UEs to extend coverage of base station 212, improve transmission reliability to one or more UEs (e.g., UE 226), and/or allow the base station to recover from a failed UE link due to, for example, blocking or fading.

Two major technologies that may be used by V2X networks include Dedicated Short Range Communications (DSRC) based on the IEEE 802.11p standard and cellular V2X based on the LTE and/or 5G (new radio) standards. Various aspects of the present disclosure may relate to a New Radio (NR) cellular V2X network, referred to herein as a V2X network for simplicity. However, it should be understood that the concepts disclosed herein may not be limited to a particular V2X standard, or may refer to a side link network other than a V2X network.

In order to achieve a low block error rate (BLER) for transmissions over the air interface while still achieving a very high data rate, channel coding may be used. That is, wireless communications may generally utilize suitable error correction block codes. In a typical block code, an information message or sequence is split into Code Blocks (CBs), and an encoder (e.g., CODEC) at the transmitting device then mathematically adds redundancy to the information message. Exploiting this redundancy in the encoded information message may increase the reliability of the message, thereby enabling correction of any bit errors that may occur due to noise.

Data coding may be implemented in a variety of ways. In the earlier 5G NR specifications, user data was decoded using quasi-cyclic Low Density Parity Check (LDPC) with two different base patterns: one base map is used for large code blocks and/or high code rates, while the other base map is used for other cases. The control information and Physical Broadcast Channel (PBCH) are decoded using polar decoding based on the nested sequences. For these channels puncturing, shortening, and repetition (repetition) are used for rate matching.

Aspects of the disclosure may be implemented using any suitable channel code. Various implementations of base stations and UEs may include suitable hardware and capabilities (e.g., encoders, decoders, and/or CODECs) to utilize one or more of these channel codes for wireless communication.

In the RAN 200, the ability of a UE to communicate independent of its location while moving is referred to as mobility. The various physical channels between the UE and the RAN are typically set up, maintained and released under control of access and mobility management functions (AMFs). In some scenarios, the AMF may include a Security Context Management Function (SCMF) and a security anchor function (SEAF) to perform authentication. The SCMF may manage the security context of both the control plane and user plane functionality in whole or in part.

In some examples, RAN 200 may implement mobility and handover (i.e., the connection of the UE is transferred from one radio channel to another radio channel). For example, during a call with a scheduling entity, or at any other time, the UE may monitor various parameters of signals from its serving cell as well as various parameters of neighboring cells. Depending on the quality of these parameters, the UE may maintain communication with one or more neighboring cells. During this time, the UE may make a handover or handoff from the serving cell to the neighboring (target) cell if the UE moves from one cell to another cell, or if the signal quality from the neighboring cell exceeds the signal quality from the serving cell for a given amount of time. For example, UE 224 may move from a geographic region corresponding to its serving cell 202 to a geographic region corresponding to neighbor cell 206. When the signal strength or quality from the neighbor cell 206 exceeds the signal strength or quality of its serving cell 202 for a given amount of time, the UE 224 may transmit a report message to its serving base station 210 indicating the condition. In response, UE 224 may receive the handover command and the UE may experience a handover to cell 206.

In various implementations, the air interface in the RAN 200 may utilize licensed spectrum, unlicensed spectrum, or shared spectrum. Licensed spectrum typically provides proprietary use of a portion of the spectrum by a mobile network operator purchasing a license from a government regulatory agency. Unlicensed spectrum provides shared use of a portion of spectrum without the need for government granted licenses. While it is still generally desirable to follow some technical rules to access the unlicensed spectrum, any operator or device may gain access. The shared spectrum may fall between licensed and unlicensed spectrum, where technical rules or restrictions may be needed to access the spectrum, but the spectrum may still be shared by multiple operators and/or multiple RATs. For example, a licensee of a portion of licensed spectrum may provide Licensed Shared Access (LSA) to share the spectrum with other parties, e.g., to gain access using conditions determined by the appropriate licensee.

The air interface in RAN 200 may utilize one or more multiplexing and multiple access algorithms to enable simultaneous communication of the various devices. For example, the 5G NR specifications provide multiple access for UL or reverse link transmissions from UEs 222 and 224 to base station 210 and utilize Orthogonal Frequency Division Multiplexing (OFDM) with a Cyclic Prefix (CP) to provide multiplexing for DL or forward link transmissions from base station 210 to UEs 222 and 224. In addition, for UL transmissions, the 5G NR specification provides support for discrete fourier transform spread OFDM (DFT-s-OFDM) with CP, also known as single carrier FDMA (SC-FDMA). However, it is within the scope of the present disclosure that multiplexing and multiple access are not limited to the above-described schemes, and may be provided using Time Division Multiple Access (TDMA), code Division Multiple Access (CDMA), frequency Division Multiple Access (FDMA), sparse Code Multiple Access (SCMA), resource Spread Multiple Access (RSMA), or other suitable multiple access schemes. Further, multiplexing DL transmissions from base station 210 to UEs 222 and 224 may be provided using Time Division Multiplexing (TDM), code Division Multiplexing (CDM), frequency Division Multiplexing (FDM), orthogonal Frequency Division Multiplexing (OFDM), sparse Code Multiplexing (SCM), or other suitable multiplexing scheme.

In addition, the air interface in the RAN 200 may utilize one or more duplexing algorithms. Duplex refers to a point-to-point communication link where two endpoints can communicate with each other in two directions. Full duplex means that two endpoints can communicate with each other at the same time. Half duplex means that only one endpoint can send information to the other endpoint at a time. Half-duplex emulation is typically implemented for wireless links using Time Division Duplexing (TDD). In TDD, transmissions in different directions on a given channel are separated from each other using time division multiplexing. That is, at some times, the channel is dedicated to transmissions in one direction, and at other times, the channel is dedicated to transmissions in the other direction, where the direction may change very rapidly, e.g., several times per slot. In wireless links, full duplex channels typically rely on physical isolation of the transmitter and receiver, as well as suitable interference cancellation techniques. Full duplex emulation is typically achieved for wireless links by utilizing Frequency Division Duplexing (FDD) or Space Division Duplexing (SDD). In FDD, transmissions in different directions may operate at different carrier frequencies (e.g., within a paired spectrum). In SDD, transmissions in different directions on a given channel are separated from each other using Space Division Multiplexing (SDM). In other examples, full duplex communications may be implemented within unpaired spectrum (e.g., within a single carrier bandwidth), where transmissions in different directions occur within different sub-bands of the carrier bandwidth. This type of full duplex communication may be referred to herein as sub-band full duplex (SBFD), also referred to as flexible duplex.

Various aspects of the disclosure will be described with reference to OFDM waveforms schematically illustrated in fig. 3. Those of ordinary skill in the art will appreciate that the various aspects of the present disclosure may be applied to SC-FDMA waveforms in substantially the same manner as described below. That is, while some examples of the present disclosure may focus on OFDM links for clarity, it should be understood that the same principles may also be applied to SC-FDMA waveforms.

Referring now to fig. 3, an expanded view of an exemplary subframe 302 is illustrated, which shows an OFDM resource grid. However, as those skilled in the art will readily appreciate, the Physical (PHY) layer transmission structure for any particular application may vary from the examples described herein depending on any number of factors. Here, the time is in a horizontal direction in units of OFDM symbols; and the frequency is in the vertical direction in units of subcarriers of the carrier.

The resource grid 304 may be used to schematically represent time-frequency resources for a given antenna port. That is, in a multiple-input multiple-output (MIMO) implementation where multiple antenna ports are available, a corresponding plurality of resource grids 304 may be available for communication. The resource grid 304 is partitioned into a plurality of Resource Elements (REs) 306. REs (which are 1 subcarrier x 1 symbol) are the smallest discrete part of the time-frequency grid and contain a single complex value representing data from a physical channel or signal. Each RE may represent one or more information bits, depending on the modulation utilized in a particular implementation. In some examples, the RE blocks may be referred to as Physical Resource Blocks (PRBs) or, more simply, resource Blocks (RBs) 308, which contain any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB may include 12 subcarriers, the number being designed independent of the parameters used. In some examples, an RB may include any suitable number of consecutive OFDM symbols in the time domain, depending on the parameter design. Within this disclosure, it is assumed that a single RB (such as RB 308) corresponds entirely to a single communication direction (transmission or reception for a given device).

The contiguous or non-contiguous set of resource blocks may be referred to herein as a Resource Block Group (RBG), subband, or bandwidth part (BWP). The set of subbands or BWP may span the entire bandwidth. Scheduling to a UE or side link device (hereinafter collectively referred to as UE) for downlink, uplink, or side link transmissions generally involves scheduling one or more resource elements 306 within one or more sub-bands or bandwidth parts (BWP). Thus, the UE typically utilizes only a subset of the resource grid 304. In some examples, an RB may be the smallest resource unit that can be allocated to a UE. Thus, the more RBs scheduled for a UE and the higher the modulation scheme selected for the air interface, the higher the data rate of that UE. The RBs may be scheduled by a base station (e.g., a gNB, eNB, etc.), or may be self-scheduled by a UE/side-link device implementing D2D side-link communication.

In this illustration, RB308 is shown to occupy less than the entire bandwidth of subframe 302, with some subcarriers above and below RB308 being illustrated. In a given implementation, subframe 302 may have a bandwidth corresponding to any number of one or more RBs 308. Further, in this illustration, RB308 is shown to occupy less than the entire duration of subframe 302, but this is merely one possible example.

Each 1ms subframe 302 may include one or more contiguous slots. As an illustrative example, in the example shown in fig. 3, one subframe 302 includes four slots 310. In some examples, a slot may be defined according to a specified number of OFDM symbols having a given Cyclic Prefix (CP) length. For example, a slot may include 7 or 12 OFDM symbols with a nominal CP. Additional examples may include mini-slots having a shorter duration (e.g., one or two OFDM symbols). In some cases, these mini-slots or shortened Transmission Time Intervals (TTIs) may be transmitted occupying resources scheduled for ongoing slot transmissions for the same or different UEs. Any number of resource blocks may be utilized within a subframe or slot.

An expanded view of one of the slots 310 illustrates the slot 310 including a control region 312 and a data region 314. In general, control region 312 may carry control channels and data region 314 may carry data channels. Of course, a slot may contain full DL, full UL, or at least one DL portion and at least one UL portion. The structure illustrated in fig. 3 is merely exemplary in nature and different time slot structures may be utilized and one or more may be included for each of the control region and the data region.

Although not illustrated in fig. 3, individual REs 306 within RBs 308 may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, and the like. Other REs 306 within an RB 308 may also carry pilot or reference signals. These pilot or reference signals may be provided to the recipient device to perform channel estimation for the corresponding channel, which may enable coherent demodulation/detection of the control and/or data channels within RB 308.

In some examples, the time slots 310 may be used for broadcast, multicast, or unicast communications. For example, broadcast, multicast, or multicast communication may refer to a point-to-multipoint transmission by one device (e.g., a base station, UE, or other similar device) to another device. Here, broadcast communications are delivered to all devices, while multicast or multicast communications are delivered to multiple target recipient devices. Unicast communication may refer to a point-to-point transmission by one device to a single other device.

In an example of cellular communication over a cellular carrier via a Uu interface, a scheduling entity (e.g., a base station) may allocate one or more REs 306 (e.g., within a control region 312) for DL transmissions to carry DL control information including one or more DL control channels, such as a Physical Downlink Control Channel (PDCCH), to one or more scheduled entities (e.g., UEs). The PDCCH carries Downlink Control Information (DCI), including, but not limited to, power control commands (e.g., one or more open-loop power control parameters and/or one or more closed-loop power control parameters), scheduling information, grants, and/or RE assignments for DL and UL transmissions. The PDCCH may further carry HARQ feedback transmissions, such as Acknowledgements (ACKs) or Negative Acknowledgements (NACKs). HARQ is a well-known technique to those of ordinary skill in the art, wherein for accuracy, the integrity of a packet transmission may be checked on the receiving side, for example, using any suitable integrity check mechanism, such as a checksum (checksum) or Cyclic Redundancy Check (CRC). If the integrity of the transmission is acknowledged, an ACK may be transmitted, and if not acknowledged, a NACK may be transmitted. In response to the NACK, the transmitting device may send HARQ retransmissions, which may enable chase combining, incremental redundancy, and so on.

The base station may further allocate one or more REs 306 (e.g., in a control region 312 or a data region 314) to carry other DL signals, such as demodulation reference signals (DMRS); phase tracking reference signal (PT-RS); channel State Information (CSI) reference signals (CSI-RS); and a Synchronization Signal Block (SSB). SSBs may be broadcast at regular intervals based on periodicity (e.g., 5, 10, 20, 80, or 120 milliseconds). SSBs include a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a physical broadcast control channel (PBCH). The UE may utilize PSS and SSS to achieve radio frame, subframe, slot, and symbol synchronization in the time domain, identify the center of channel (system) bandwidth in the frequency domain, and identify the Physical Cell Identity (PCI) of the cell.

The PBCH in SSB may further include: a Master Information Block (MIB) that includes various system information and parameters for decoding a System Information Block (SIB). The SIB may be, for example, system information type1 (SIB 1), which may include various additional system information. The MIB and SIB1 together provide minimum System Information (SI) for initial access. Examples of system information transmitted in the MIB may include, but are not limited to: subcarrier spacing (e.g., default downlink parameter design), system frame number, configuration of PDCCH control resource set (CORESET) (e.g., PDCCH CORESET 0), cell prohibit indicator, cell reselection indicator, raster offset, and search space for SIB 1. Examples of Remaining Minimum System Information (RMSI) transmitted in SIB1 may include, but are not limited to, random access search space, paging search space, downlink configuration information, and uplink configuration information.

In UL transmissions, a scheduled entity (e.g., UE) may utilize one or more REs 306 to carry UL Control Information (UCI) to the scheduling entity, including one or more UL control channels, such as a Physical Uplink Control Channel (PUCCH). UCI may include various packet types and categories including pilot, reference signals, and information configured to enable or assist in decoding uplink data transmissions. Examples of uplink reference signals may include Sounding Reference Signals (SRS) and uplink DMRS. In some examples, UCI may include a Scheduling Request (SR), i.e., a request for a scheduling entity to schedule uplink transmissions. Here, in response to the SR transmitted on the UCI, the scheduling entity may transmit Downlink Control Information (DCI) which may schedule resources for uplink packet transmission. UCI may also include HARQ feedback, channel State Feedback (CSF) (such as CSI reporting), or any other suitable UCI.

In addition to control information, one or more REs 306 (e.g., within data region 314) may also be allocated for data traffic. Such data traffic may be carried on one or more traffic channels, such as on a Physical Downlink Shared Channel (PDSCH) for DL transmissions; or may be carried on a Physical Uplink Shared Channel (PUSCH) for UL transmissions. In some examples, one or more REs 306 within data region 314 may be configured to carry other signals, such as one or more SIBs and DMRSs.

In an example of side link communication over a side link carrier via a PC5 interface, the control region 312 of the slot 310 may include a physical side link control channel (PSCCH) that includes side link control information (SCI) transmitted by an initiator (transmitting) side link device (e.g., a Tx V2X device or other Tx UE) to a set of one or more other receiver side link devices (e.g., an Rx V2X device or other Rx UE). The data region 314 of the slot 310 may include a physical side link shared channel (PSSCH) that includes side link data traffic transmitted by an initiator (transmitting) side link device within resources reserved by the transmitting side link device via the SCI on side link carriers. Other information may be further transmitted on each RE 306 within the time slot 310. For example, HARQ feedback information may be transmitted from the receiver-side link device to the transmitting side link device in a physical side link feedback channel (PSFCH) within the time slot 310. Further, one or more reference signals, such as side link SSB, side link CSI-RS, side link SRS, and/or side link Positioning Reference Signals (PRS), may be transmitted within the slot 310.

These physical channels are typically multiplexed and mapped to transport channels for handling by the Medium Access Control (MAC) layer. The transport channel carries blocks of information, which are called Transport Blocks (TBs). The Transport Block Size (TBS), which may correspond to the number of information bits, may be a controlled parameter based on the Modulation and Coding Scheme (MCS) and the number of RBs in a given transmission.

The channels or carriers illustrated in fig. 3 are not necessarily all channels or carriers available between devices, and one of ordinary skill in the art will recognize that other channels or carriers may be utilized in addition to those illustrated, such as other traffic, control, and feedback channels.

Fig. 4 illustrates an example of a wireless communication network 400 configured to support D2D or side link communications. In some examples, the side link communication may include V2X communication. V2X communication involves not only direct wireless information exchange between the vehicles (e.g., vehicles 402 and 404) themselves, but also between the vehicles 402/404 and the infrastructure (e.g., road Side Units (RSUs) 406), such as street lamps, buildings, traffic cameras, tollgates, or other stationary objects, the vehicles 402/404 and pedestrians 408, and the vehicles 402/404 and the wireless communication network (e.g., base stations 410). In some examples, V2X communication may be implemented according to the New Radio (NR) cellular V2X standard defined by 3GPP (release 16) or other suitable standards.

V2X communications enable vehicles 402 and 404 to obtain information related to weather, nearby accidents, road conditions, nearby vehicle and pedestrian activity, objects in the vicinity of the vehicle, and other relevant information that may be used to improve the vehicle driving experience and enhance vehicle safety. For example, such V2X data may enable autonomous driving and improve road safety and traffic efficiency. For example, V2X connected vehicles 402 and 404 may utilize the exchanged V2X data to provide in-vehicle collision warnings, road hazard warnings, approaching emergency vehicle warnings, pre-crash/post-crash warnings and information, emergency braking warnings, forward traffic congestion warnings, lane change warnings, intelligent navigation services, and other similar information. Additionally, V2X data received by V2X connected mobile devices of the pedestrian/cyclist 408 may be used to trigger warning sounds, vibrations, flashing lights, etc. in the event of an impending hazard.

Side link communications between vehicle UEs (V-UEs) 402 and 404, or between V-UE 402 or 404 and RSU 406 or pedestrian UE (P-UE) 408, may occur on side link 412 using a proximity services (ProSe) PC5 interface. In various aspects of the present disclosure, the PC5 interface may be further used to support D2D side link 412 communications in other proximity use cases (e.g., in addition to V2X). Examples of other proximity use cases may include smart wearable devices, public safety, or business (e.g., entertainment, education, office, medical, and/or interactive) based proximity services. In the example shown in fig. 4, proSe communication may further occur between UEs 414 and 416.

ProSe communication can support different operating scenarios, such as in-coverage, out-of-coverage, and partial coverage. Out-of-coverage refers to a scenario in which UEs (e.g., UEs 414 and 416) are outside the coverage area of a base station (e.g., base station 410), but each UE is still configured for ProSe communication. Partial coverage refers to a scenario in which some UEs (e.g., V-UE 404) are outside the coverage area of base station 410, while other UEs (e.g., V-UE 402 and P-UE 408) are in communication with base station 410. In-coverage refers to a scenario in which UEs (e.g., V-UE 402 and P-UE 408) are in communication with base station 410 (e.g., gNB) via Uu (e.g., cellular interface) connections to receive ProSe service grants and provisioning information to support ProSe operation.

To facilitate D2D side link communication over side link 412, for example, between UEs 414 and 416, UEs 414 and 416 may communicate discovery signals therebetween. In some examples, each discovery signal may include a synchronization signal, such as a Primary Synchronization Signal (PSS) and/or a Secondary Synchronization Signal (SSS), that facilitate device discovery and enable communication synchronization on the side link 412. For example, the discovery signal may be used by UE 416 to measure the signal strength and channel state of a potential side link (e.g., side link 412) with another UE (e.g., UE 414). The UE 416 may utilize these measurements to select a UE (e.g., UE 414) for side link communication or relay communication.

In the 5G NR side link, side link communications may utilize a pool of transmission or reception resources. For example, the smallest resource allocation unit in frequency may be a subchannel (e.g., which may comprise, for example, 10, 15, 20, 25, 50, 75, or 100 consecutive resource blocks), and the smallest resource allocation unit in time may be one slot. The Radio Resource Control (RRC) configuration of the resource pool may be preconfigured (e.g., factory settings on the UE, e.g., as determined by the side link standards or specifications) or configured by the base station (e.g., base station 410).

In addition, side link (e.g., PC 5) communications may have two primary modes of resource allocation operation. In a first mode (mode 1), a base station (e.g., a gNB) 410 may allocate resources to side link devices (e.g., V2X devices or other side link devices) for side link communication among the side link devices in various manners. For example, the base station 410 may dynamically allocate side link resources (e.g., dynamic grants) to the side link devices in response to side link resource requests from the side link devices. The base station 410 may further activate a pre-configured side link grant (e.g., a configured grant) for side link communication between side link devices. In mode 1, side link feedback may be reported back to the base station 410 by the transmitting side link device.

In the second mode (mode 2), the side link device may autonomously select side link resources for side link communication between them. In some examples, a transmitting side chain device may perform resource/channel sensing to select unoccupied resources (e.g., subchannels) on a side chain channel. Signaling on the side link is the same between the two modes. Thus, from the receiver's perspective, there is no distinction between these modes.

In some examples, side link (e.g., PC 5) communications may be scheduled using side link control information (SCI). SCI may include two SCI stages. The phase 1 side link control information (first phase SCI) may be referred to herein as SCI-1. The phase 2 side link control information (second phase SCI) may be referred to herein as SCI-2.

SCI-1 may be transmitted on a physical side link control channel (PSCCH). SCI-1 may include resource allocation for side link resources and information for decoding side link control information (i.e., SCI-2) of the second stage. SCI-1 may further identify a priority level (e.g., quality of service (QoS)) of the PSSCH. For example, ultra-reliable low latency communication (URLLC) traffic may have a higher priority than short message traffic (e.g., short Message Service (SMS) traffic). SCI-1 may also include a physical side link shared channel (PSSCH) resource assignment and a resource reservation period (if enabled). Additionally, SCI-1 may include PSSCH demodulation reference signal (DMRS) patterns (if more than one pattern is configured). The DMRS may be used by a receiver for radio channel estimation for demodulation of an associated physical channel. As indicated, SCI-1 may also include information about SCI-2, e.g., SCI-1 may disclose the format of SCI-2. Here, the format indicates a resource size of SCI-2 (e.g., the number of REs allocated for SCI-2), a PSSCH DMRS port number, and a Modulation and Coding Scheme (MCS) index. In some examples, SCI-1 may use two bits to indicate SCI-2 format. Thus, in this example, four different SCI-2 formats may be supported. SCI-1 may include other information useful for establishing and decoding PSSCH resources.

SCI-2 may also be transmitted on the PSCCH and may contain information for decoding the PSCCH. According to some aspects, SCI-2 includes a 16-bit layer 1 (L1) destination Identifier (ID), an 8-bit L1 source ID, a hybrid automatic repeat request (HARQ) process ID, a New Data Indicator (NDI), and a Redundancy Version (RV). For unicast communications, SCI-2 may further include a CSI report trigger. For multicast communications, SCI-2 may further include a zone identifier and a maximum communication range of NACKs. SCI-2 may include other information useful for establishing and decoding PSSCH resources.

Fig. 5A and 5B are diagrams illustrating examples of side link slot structures according to some aspects. The side-link slot structure may be utilized, for example, in a V2X or other D2D network implementing side links. In the example shown in fig. 5A and 5B, time is in the horizontal direction in units of symbols 502 (e.g., OFDM symbols); and the frequency is in the vertical direction. Here, carrier bandwidth 504 allocated for side-link wireless communication is illustrated along the frequency axis. The carrier bandwidth 504 may include a plurality of sub-channels, where each sub-channel may include a configurable number of PRBs (e.g., 10, 14, 20, 24, 40, 44, or 100 PRBs).

Each of fig. 5A and 5B illustrates an example of a respective slot 500a or 500B that includes fourteen symbols 502 that may be used for side link communications. However, it should be appreciated that side link communications may be configured to occupy less than fourteen symbols in a slot 500a or 500b, and the present disclosure is not limited to any particular number of symbols 502. Each side link slot 500a and 500b includes a physical side link control channel (PSCCH) 506 occupying a control region 518 of slots 500a and 500b and a physical side link shared channel (PSSCH) 508 occupying a data region 520 of slots 500a and 500 b. PSCCH 506 and PSCCH 508 are each transmitted on one or more symbols 502 of slot 500 a. PSCCH 506 comprises, for example, SCI-1, which schedules transmission of data traffic on time-frequency resources corresponding to pscsch 508. As shown in fig. 5A and 5B, PSCCH 506 and corresponding pscsch 508 are transmitted in the same time slots 500a and 500B. In other examples, PSCCH 506 may schedule a PSCCH in a subsequent slot.

In some examples, the PSCCH 506 duration is configured as two or three symbols. In addition, PSCCH 506 may be configured to span a configurable number of PRBs, limited to a single subchannel. For example, PSCCH 506 may span 10, 12, 14, 20, or 24 PRBs of a single subchannel. DMRS may further be present in each PSCCH symbol. In some examples, the DMRS may be placed on every fourth RE of PSCCH 506. Frequency domain orthogonal cover codes (FD-OCCs) may be further applied to PSCCH DMRS to reduce the impact of conflicting PSCCH transmissions on side link channels. For example, the transmitting UE may randomly select FD-OCCs from a set of predefined FD-OCCs. In each of the examples shown in fig. 5A and 5B, the starting symbol of PSCCH 506 is the second symbol of the corresponding slot 500a or 500B, and PSCCH 506 spans three symbols 502.

The PSCCH 508 may be Time Division Multiplexed (TDM) with the PSCCH 506 and/or Frequency Division Multiplexed (FDM) with the PSCCH 506. In the example shown in fig. 5A, the PSCCH 508 includes a first portion 508a that is TDM with the PSCCH 506 and a second portion 508b that is FDM with the PSCCH 506. In the example shown in fig. 5B, PSCCH 508 is TDM with PSCCH 506.

One-layer transmission and two-layer transmission of the PSSCH 508 may be supported by various modulation orders, such as Quadrature Phase Shift Keying (QPSK), 16 quadrature amplitude modulation (16-QAM), 64-QAM, and 246-QAM. In addition, the PSSCH 508 may include a DMRS 514 configured in a two-symbol, three-symbol, or four-symbol DMRS pattern. For example, the slot 500a shown in fig. 5A illustrates a two-symbol DMRS pattern, while the slot 500B shown in fig. 5B illustrates a three-symbol DMRS pattern. In some examples, the transmitting UE may select a DMRS pattern according to channel conditions and indicate the selected DMRS pattern in SCI-1. The DMRS pattern may be selected, for example, based on the number of PSSCH 508 symbols in the slot 500a or 500 b. In addition, in each slot 500a and 500b, a gap symbol 516 exists after the PSSCH 508.

Each slot 500a and 500b further includes SCI-2,512, which maps from the first symbol containing PSSCH DMRS to consecutive RBs in PSSCH 508. In the example shown in fig. 5A, the first symbol containing PSSCH DMRS is the fifth symbol that occurs immediately after the last symbol carrying PSCCH 506. Thus, SCI-2,512 is mapped to RBs within the fifth symbol. In the example shown in fig. 5B, the first symbol comprising PSSCH DMRS is the second symbol, which also includes PSCCH 506. In addition, SCI-2/PSSCH DMRS 512 is shown spanning symbols two through five. As a result, SCI-2/PSSCH DMRS 512 can FDM with PSCCH 506 in symbols two through four and TDM with PSCCH 506 in symbol five.

SCI-2 may be scrambled separately from the side link shared channel. In addition, SCI-2 may utilize QPSK. When the PSSCH transmission spans two layers, the SCI-2 modulation symbol can be replicated (e.g., repeated) on both layers. SCI-1 in PSCCH 506 may be blind decoded at the receiving wireless communication device. However, since the format, starting location and number of REs of SCI-2 512 can be derived from SCI-1, blind decoding of SCI-2 is not required at the receiver (recipient UE).

In each of fig. 5A and 5B, the second symbol of each slot 500a and 500B is copied onto its first symbol 510 (repeated on its first symbol 510) for Automatic Gain Control (AGC) stabilization. For example, in fig. 5A, a second symbol comprising a PSCCH 506 with a psch 508b that is FDM may be transmitted on both the first symbol and the second symbol. In the example shown in fig. 5B, a second symbol containing the PSCCH 506 with SCI-2/PSSCH DMRS 512 for FDM may be transmitted on both the first symbol and the second symbol.

Fig. 6 is a diagram illustrating an example of a side-chain slot structure with feedback resources, according to some aspects. The side-link slot structure may be utilized, for example, in a V2X or other D2D network implementing side links. In the example shown in fig. 6, time is in the horizontal direction in units of symbols 602 (e.g., OFDM symbols); and the frequency is in the vertical direction. Here, carrier bandwidth 604 allocated for side-link wireless communication is illustrated along the frequency axis. A slot 600 having the slot structure shown in fig. 6 includes fourteen symbols 602 that may be used for side link communications. However, it should be understood that side link communications may be configured to occupy less than fourteen symbols in the slot 600, and the present disclosure is not limited to any particular number of symbols 602.

As in fig. 6A and 6B, the side link slot 600 includes a PSCCH 606 occupying the control region of the slot 600 and a PSCCH 608 occupying the data region 620 of the slot 600. PSCCH 606 and PSCCH 608 are each transmitted on one or more symbols 602 of slot 600 a. PSCCH 606 comprises, for example, SCI-1, which schedules transmission of data traffic on time-frequency resources corresponding to pscsch 608. As shown in fig. 6, the starting symbol of PSCCH 606 is the second symbol of slot 600 and PSCCH 606 spans three symbols 602. The PSCCH 608 may be Time Division Multiplexed (TDM) with the PSCCH 606 and/or Frequency Division Multiplexed (FDM) with the PSCCH 606. In the example shown in fig. 6, the PSCCH 608 includes a first portion 608a that is TDM with the PSCCH 606 and a second portion 608b that is FDM with the PSCCH 606.

The PSSCH 608 may further include a DMRS 614 configured in a two-symbol, three-symbol, or four-symbol DMRS pattern. For example, the slot 600 shown in fig. 6 illustrates a two symbol DMRS pattern. In some examples, the transmitting UE may select a DMRS pattern according to channel conditions and indicate the selected DMRS pattern in SCI-1. The DMRS pattern may be selected, for example, based on the number of PSSCH 608 symbols in slot 600. In addition, in slot 600, a gap symbol 616 exists after PSSCH 608.

Slot 600 further includes SCI-2 612, which maps to consecutive RBs in PSSCH 608 from the first symbol comprising PSSCH DMRS. In the example shown in fig. 6, the first symbol containing PSSCH DMRS is the fifth symbol that occurs immediately after the last symbol carrying PSCCH 606. Thus, SCI-2 612 is mapped to RBs within the fifth symbol.

Further, as shown in fig. 6, the second symbol of the slot 600 is copied onto its first symbol 610 (repeated on its first symbol 610) for Automatic Gain Control (AGC) stabilization. For example, in fig. 6, a second symbol comprising a PSCCH 606 with a PSCCH 608b for FDM may be transmitted on both the first symbol and the second symbol.

HARQ feedback may also be transmitted on a physical side link feedback channel (PSFCH) 618 within a configurable resource period of 0, 1, 2, or 4 slots. In a side link slot (e.g., slot 600) containing PSFCH 618, one symbol 602 may be allocated to PSFCH 618, and PSFCH 618 may be copied onto a previous symbol (repeated on a previous symbol) for AGC settling. In the example shown in fig. 6, PSFCH 618 is transmitted on the thirteenth symbol and copied onto the twelfth symbol in slot 600 c. A gap symbol 616 may be further placed after the PSFCH symbol 618.

In some examples, there is a mapping between the PSSCH 608 and the corresponding PSFCH resource. The mapping may be based on, for example, a starting subchannel of the PSSCH 608, a slot containing the PSSCH 608, a source ID, and a destination ID. In addition, PSFCH may be enabled for unicast and multicast communications. For unicast, the PSFCH may include one ACK/NACK bit. For multicast, there may be two feedback modes for the PSFCH. In the first multicast PSFCH mode, the receiving UE transmits only a NACK, while in the second multicast PSFCH mode, the receiving UE may transmit an ACK or NACK. In the second multicast PSFCH mode, the number of available PSFCH resources may be equal to or greater than the number of UEs.

A wireless device, such as a UE, may periodically turn off (or turn off its Radio Frequency (RF) communication circuitry) to save power. In an aspect, a Discontinuous Reception (DRX) mode may be defined such that a DRX cycle in the DRX mode has an ON (ON) duration during which the UE may be turned ON for wireless communication and an OFF (OFF) duration during which the UE may be turned OFF (e.g., by turning OFF its RF communication circuitry or the entire UE). The DRX cycle may be repeated during the DRX mode. In particular, the DRX mode may be defined by a start time of the DRX mode, a number of DRX cycles in the DRX mode, a DRX cycle length, and an on duration for turning on the UE during the DRX cycle, and an offset from a reference time for starting the DRX mode. For example, when implementing a DRX mode, the UE may wake up only 10 milliseconds (msec) every 300 msec for a DRX cycle, where the DRX mode starts with the first instance of the DRX cycle after an offset from the reference time.

In communication between the UE and the base station (e.g., via the Uu interface), the reference time for the DRX mode may be associated with a System Frame Number (SFN) timing, and thus the offset from the reference time may be an offset with respect to the system frame. On the other hand, in side link communications, one or more UEs may not have SFN. For example, if some UEs are not connected to the network, the UEs may not have SFNs. In an example, a UE time synchronized with a Global Navigation Satellite System (GNSS) may utilize Direct Frame Number (DFN) timing as a reference time for DRX mode instead of relying on SFN timing.

Thus, in side link communications, different UEs may have different frame numbers and frame boundaries for frames respectively associated with SFNs (e.g., SFN values) for a particular time. In an example, UEs connected to different networks may have different SFNs at a particular time because such UEs may have different SFN timings from one another. Further, in an example, if different networks are synchronized to GNSS time, the system frame boundaries (e.g., associated with SFNs) of the different networks may be aligned, but their SFN values may be different at a particular time. Thus, relying on SFN timing to determine DFN timing for a UE may result in different DFN timing for different UEs.

If each of the two UEs is in DRX mode, the UEs may communicate with each other (e.g., via a side link) when the on-duration of the DRX cycle for one UE overlaps in time with the on-duration of the DRX cycle for the other UE. If different UEs use different DFN timings, the on-duration of the DRX cycle for one UE may not overlap with the on-duration of the DRX cycle for another UE, and thus, side-chain communication between these UEs may not be possible. This problem may occur, for example, when one UE is synchronized to a network (e.g., by connecting to the network) and another UE is synchronized to GNSS time (e.g., when not connected to the network) or to a different network. Thus, to allow UEs to communicate via the side link during the DRX mode, the UEs may be configured to have the same or substantially overlapping DRX cycles (e.g., on-durations of DRX cycles) regardless of whether each UE is connected to a network and/or regardless of which network each UE is connected to.

Fig. 7A and 7B are example diagrams illustrating timing of two DRX modes by different UEs, according to some aspects. Fig. 7A is an example diagram 700 illustrating an example DRX mode, according to some aspects. The DRX pattern in fig. 7A includes DRX cycles 706, 708, and 710, and begins after an offset duration 704 from the reference time 702. Fig. 7A also shows on duration 716 of DRX cycle 706 and off duration 718 of DRX cycle 706, on duration 720 of DRX cycle 708 and off duration 722 of DRX cycle 708, and on duration 724 of DRX cycle 710 and off duration 726 of DRX cycle 710. For example, referring to DRX cycle 706, the duration of DRX cycle 706 may be 300 milliseconds, the duration 712 of the on duration may be 10 milliseconds, and the duration 714 of the off duration may be 290 milliseconds. The DRX cycle duration of the DRX cycle may be a combined duration of the on duration and the off duration. For example, the DRX cycle duration of DRX cycle 706 is the sum of the duration 712 of the on duration and the duration 714 of the off duration.

Fig. 7B is an example diagram 750 illustrating an example DRX mode, according to some aspects. The DRX pattern in fig. 7B includes DRX cycles 756, 758, and 760 and begins after an offset duration 752 from a reference time 754. Fig. 7B further illustrates on duration 766 of DRX cycle 756 and off duration 768 of DRX cycle 756, on duration 770 of DRX cycle 758 and off duration 772 of DRX cycle 758, and on duration 774 of DRX cycle 760 and off duration 776 of DRX cycle 760. For example, referring to DRX cycle 756, the duration of DRX cycle 756 may be 300 milliseconds, the duration 762 of the on duration may be 10 milliseconds, and the duration 764 of the off duration may be 290 milliseconds. The DRX cycle duration of the DRX cycle may be a combined duration of the on duration and the off duration. For example, the DRX cycle duration of DRX cycle 756 is a combined duration of the duration 762 of the on duration and the duration 764 of the off duration.

The reference time 702 for the first UE in fig. 7A is significantly different from the reference time 752 for the second UE in fig. 7B. For example, such a difference in reference time may be due to the UE not utilizing the same SFN timing or the same DFN timing. Thus, the on-durations of DRX cycles 706, 708, and 710 for the first UE in fig. 7A do not overlap with the on-durations of DRX cycles 756, 758, and 760 for the second UE in fig. 7B. Thus, during the DRX mode, the first UE and the second UE cannot communicate with each other via the side link.

According to some aspects of the disclosure, the UE may configure the side link DRX mode using one or more side link DRX parameters based on the DFN timing such that the UE may perform side link communication with the second UE during an on duration of the side link DRX cycle according to the one or more side link DRX parameters determined based on the DFN timing. Thus, instead of relying on SFN timing, the UE may rely on DFN timing to implement the side link DRX mode. In an aspect, the second UE may also rely on DFN timing to implement the side link DRX mode. For example, relying on DFN timing to implement the side link DRX mode is advantageous because DFN timing may be substantially the same across different UEs, regardless of whether each UE is connected to a network (e.g., in network coverage) and/or regardless of which network each UE is connected to.

In an aspect, the side link DRX parameter(s) may include at least one of: an on duration of a side link DRX cycle, an offset duration indicating a delay between a reference time for initiating the side link DRX mode and a first instance of the DRX cycle, a DRX cycle duration, or a number of DRX cycles for the side link DRX mode. For example, referring back to fig. 7a, the ue may configure the DRX mode using side link DRX parameters including an on duration, an offset duration, a DRX cycle duration, and a DRX cycle number to determine the duration of each of the on duration 716, the offset duration 704, the DRX cycles 706, 708, and 710, and the DRX cycle number to be three, respectively. In an aspect, the side-chain DRX parameter(s) may also include an inactivity timer, which may be used to determine an amount of time that the UE remains on after receiving the signal (e.g., during the on duration).

In an aspect, the offset duration indicating a delay between a reference time for initiating the side link DRX mode and the first instance of the DRX cycle may be based on a DFN value corresponding to the DFN timing, a subframe number of a subframe associated with the DFN value, and a duration of the side link DRX cycle. The DFN value may correspond to a direct frame used for SL transmission for the sidelink DRX cycle. In an example, the DFN value may correspond to a first direct frame of a first sidelink DRX cycle. The subframe number may correspond to a subframe within a direct frame of DFN values. In an example, the subframe number may correspond to a subframe in which a side link DRX cycle is initiated. For example, the DFN values may range from 0 to 1023, and the subframe numbers may range from 0 to 9, as each DFN includes 10 subframes, with each subframe having a duration of 1 millisecond. In an example, the base station may transmit the DFN value via the PBCH and the UE may receive the DFN value via the PBCH.

In an aspect, the offset duration may be calculated based on a remainder of a sum of the sub-frame number and a product of the DFN value and 10 divided by a duration of the side link DRX cycle. For example, the offset duration may be determined based on the following equation (1):

sl-drx-StartOffset＝[(DFN×10)+subframe number]modulo(sl-drx-Cycle),(1)

where sl-DRX-StartOffset is the offset duration, DFN is the DFN value, subframe number is the subframe number of the subframe associated with the DFN value, and sl-DRX-Cycle is the duration of the side-link DRX Cycle.

In an aspect, a UE may determine DFN timing. In this aspect, the UE may determine a GNSS time and determine a DFN timing based on the GNSS time. For example, the GNSS time may be determined by a GPS device in or connected to the UE. For example, whether the UE is in network coverage or outside network coverage, the DFN timing or DFN value corresponding to the DFN timing may be derived based on coordinated Universal Time (UTC) provided by GNSS (e.g., GNSS timing). In examples where the UE is in network coverage but is using GNSS as a synchronization source for SL communication, the DFN value may be derived from GNSS timing and timing offset relative to a cell timing reference (e.g., a reference time of a cell serving the UE). In examples where the UE is in network coverage and does not use GNSS for synchronization, the DFN value may be derived based on an SFN value that provides an index to the frame based on the cell timing reference.

In another aspect, the UE may receive a DFN indicator from the base station and determine a DFN timing based on the DFN indicator. In an aspect, a base station may determine a DFN indicator and transmit the DFN indicator to a UE. The UE may determine DFN timing based on the DFN indicator and then determine a side link DRX mode using the side link DRX parameter(s) based on the DFN indicator. The DFN indicator may be transmitted via a System Information Block (SIB), a Radio Resource Control (RRC) message, a Physical Broadcast Channel (PBCH), and/or a medium access control-control element (MAC-CE).

For example, in some cases, if the UE does not have reliable GPS reception in certain locations (e.g., urban scenarios with high buildings) or has an unavailable or off GPS device, the UE may not be able to determine GNSS time by itself to determine DFN timing. In these cases, the UE may receive a DFN indicator from the base station to determine a DFN timing based on the DFN indicator.

In an aspect, the DFN indicator may include one or more of: offset values indicating the difference between the DFN timing and the SFN timing associated with the base station, the DFN timing, and the GNSS time. The offset value indicating the difference between the DFN timing and the SFN timing may be a time difference between the DFN timing and the SFN timing, or may be a frame number difference between the DFN timing and the SFN timing.

In an aspect, an offset value indicating a difference between DFN timing and SFN timing and/or DFN timing may be based on GNSS time. In an aspect, the offset value and/or DFN timing may be determined by the base station based on GNSS time. In an example, the base station may determine the offset value based on GNSS time and transmit the offset value to the UE. In an aspect, the offset value may be represented by a number of frame offsets or by an offset time. In an example, if the offset value indicates 10 milliseconds, the UE may apply an offset of +10 milliseconds to the SFN timing to determine the DFN timing. In another example, if the offset value indicates-5 milliseconds, the UE may apply an offset of-5 milliseconds to the SFN timing to determine the DFN timing. In an example, if the offset value indicates 3 frames, the UE may determine that the DFN timing is an offset of +3 frames from the SFN timing. In another example, if the offset value indicates-2 frames, the UE may determine that the DFN timing is an offset of-2 frames from the SFN timing. In an example, the base station may determine the offset value based on GNSS time, determine DFN timing based on the offset value, and then transmit the DFN timing to the UE.

Fig. 8 is an example diagram 800 illustrating interactions between UEs and possible interactions of UEs with respective base stations, according to some aspects. In fig. 8, the first UE 812 and the second UE 822 may perform side link communication directly with each other via a side link 832. As discussed above, in an aspect, the first UE 812 may determine one or more first side link DRX parameters for the first side link DRX cycle for the first UE 812 and for the side link 832 based on the first DFN timing. The first UE 812 may then perform side link communication with the second UE 822 during the on period of the first side link DRX cycle in the first side link DRX mode according to the first side link DRX parameter(s). In an aspect, in fig. 8, a first UE 812 may be connected to a first network 850 operated by a first base station 852 and may communicate with the first base station 852 via a first Uu interface 862. In an aspect, the first UE 812 may determine a first DFN timing (e.g., based on GNSS time acquired by the first UE 812). In an aspect, the first UE 812 may receive a first DFN indicator from the first base station 852 and then determine a first DFN timing based on the first DFN indicator to configure the first sidelink DRX mode based on the first DFN timing.

In an aspect, the second UE 822 may configure the second side link DRX mode based on the second DFN timing using one or more second side link DRX parameters for the second UE 822 and the side link 832. The second UE 822 may then perform side link communication with the first UE 812 during the on period of the second side link DRX cycle in the second side link DRX mode according to the second side link DRX parameter(s). In one aspect (not shown in fig. 8), the second UE 822 may not be connected to a network operated by the base station. In another aspect, in fig. 8, the second UE 822 may be connected to a second network 870 operated by a second base station 872 and may communicate with the second base station 872 via a second Uu interface 882. In an aspect, the second UE 822 may determine a second DFN timing (e.g., based on GNSS time acquired by the second UE 822). In an aspect, the second UE 822 may receive the second DFN indicator from the first base station 852 and then determine the first DFN timing based on the second DFN indicator to configure the second side link DRX mode based on the second DFN timing.

The first DFN timing determined by the first UE 812 may correspond to or substantially correspond to the second DFN timing determined by the second UE 822 such that direct frames based on the first DFN timing at least substantially overlap (e.g., have at least 50% overlap) with direct frames based on the second DFN timing. For example, if a first direct frame (e.g., DFN 0) based on a second DFN timing overlaps at least 50% of a first direct frame (e.g., DFN 0) based on the first DFN timing, the second DFN timing may be determined to substantially overlap the first DFN timing. For example, the first DFN timing and the second DFN timing may be determined based on GNSS time or based on respective DFN indicators based on GNSS time. The GNSS time may be the same throughout the different devices, and thus the first DFN timing may correspond to or substantially correspond to the second DFN timing, as the first DFN timing and the second DFN timing are based on GNSS time or based on respective DFN indicators that are based on GNSS time. If the first DFN timing corresponds to or substantially corresponds to the second DFN timing, the first side link DRX mode configured based on the first DFN timing corresponds to or substantially corresponds to the second side link DRX mode configured based on the second DFN timing. Thus, the on-duration of the first side link DRX cycle for the first UE 812 may completely or substantially overlap with the on-duration of the second side link DRX cycle for the second UE 822.

In an aspect, the base station may transmit a GNSS synchronization indicator to the UE indicating whether the base station is synchronized to GNSS time. When the UE receives the GNSS synchronization indicator from the base station, the UE may further perform side link communication based on the GNSS synchronization indicator. For example, if the base station is synchronized to GNSS time, the boundaries of the direct frames determined based on GNSS time (e.g., GNSS-based direct frames) may be aligned with the boundaries of the system frames having the corresponding SFNs. Thus, if the base station is synchronized to GNSS time, the DFN timing determined based on the SFN timing associated with the base station (e.g., using an offset value) may align the boundary of the direct frame based on the DFN timing with the boundary of the direct frame based on the GNSS. On the other hand, if the base station is not synchronized to GNSS time, the boundaries of the direct frame based on GNSS may not be aligned with the boundaries of the system frame. Thus, if the base station is not synchronized to GNSS time, the DFN timing determined based on the SFN timing associated with the base station (e.g., using an offset value) may cause the boundary of the direct frame based on the DFN timing to not align with the boundary of the direct frame based on GNSS.

In an aspect, if the GNSS synchronization indicator from the base station indicates that the base station is not synchronized to GNSS time, the UE may refrain from transmitting side link communications to the second UE during at least a portion of a first frame corresponding to a first DFN based on the DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on the DFN timing. For example, suppressing transmissions during at least a portion of the first frame and/or at least a portion of the last frame may be beneficial because if the base station is not synchronized to GNSS time, the frame boundaries of the direct frame based on SFN timing may not be aligned with the boundaries of the direct frame based on GNSS. On the other hand, if the GNSS synchronization indicator indicates that the base station is synchronized to GNSS time, the UE may communicate the side-link communication to the second UE using the first frame and/or the last frame.

Fig. 9A is an example diagram 900 illustrating DFN timing-based direct frames (the DFN timing being determined based on SFN timing), system frames, and GNSS-based direct frames when a base station is synchronized to GNSS time, according to some aspects. In the example of fig. 9A, because the base station is synchronized to GNSS time, the frame boundaries of the GNSS based direct frame 910 are aligned with the frame boundaries of the system frame 920 associated with the base station. Thus, in fig. 9A, the DFN timing determined based on the SFN timing associated with the system frame 920 may align the frame boundary of the direct frame 930 based on the SFN timing (e.g., using an offset value) with the boundary of the direct frame 910 based on the GNSS. In fig. 9A, an offset value indicating a difference between DFN timing and SFN timing associated with a base station is 3 frames. Thus, SFN 3 may correspond to DFN 0, for example.

Fig. 9B is an example diagram 950 illustrating DFN timing-based direct frames (the DFN timing being determined based on SFN timing), system frames, and GNSS-based direct frames when a base station is not synchronized to GNSS time, according to some aspects. In the example of fig. 9B, because the base station is not synchronized to GNSS time, the frame boundaries of the GNSS based direct frame 960 are not aligned with the frame boundaries of the system frame 970 associated with the base station. Thus, in fig. 9B, the DFN timing determined based on the SFN timing associated with the system frame 970 may cause the frame boundaries (e.g., using offset values) of the direct frame 980 based on the SFN timing to not be perfectly aligned with the boundaries of the direct frame 960 based on the GNSS. As shown in fig. 9B, although DFN 0 and DFN 1 of the SFN timing based direct frame 980 substantially overlap with DFN 0 and DFN 1, respectively, of the GNSS based direct frame 960, the SFN timing based direct frame 980 starts slightly later than the GNSS based direct frame 960. In fig. 9B, the offset value indicating the difference between the DFN timing and the SFN timing associated with the base station is 3 frames. Thus, SFN 3 may correspond to DFN 0, for example.

Fig. 10A-10C are example diagrams illustrating three DRX modes based on three DFN timings, according to some aspects. Fig. 10A is an example diagram 1000 illustrating an example DRX mode configured based on GNSS based DFN timing, according to some aspects. For example, the DRX pattern of example diagram 1000 may correspond to the GNSS-based DFN timing of GNSS-based direct frame 910 of fig. 9A or GNSS-based direct frame 960 of fig. 9B. The DRX pattern in fig. 10A includes DRX cycles (such as DRX cycles 1006 and 1008) and begins after an offset duration 1004 from a reference time 1002 of the GNSS based DFN timing. Fig. 10A shows an on duration 1016 of DRX cycle 1006 having an on duration length 1012 and an off duration 1018 of DRX cycle 1006 having an off duration length 1014. Similarly, fig. 10A further illustrates an on duration 1020 of the DRX cycle 1008 and an off duration 1022 of the DRX cycle 1008. In an aspect, the offset duration 1004 may be calculated based on equation (1) discussed above, where the DFN value may correspond to a first direct frame in the DRX cycle 1006, the subframe number may correspond to a subframe within the first direct frame in the DRX cycle 1006 in which the DRX cycle 1006 begins, and the duration of the side link DRX cycle may correspond to the duration of the DRX cycle 1006.

Fig. 10B is an example diagram 1030 illustrating an example DRX mode configured based on DFN timing (the DFN timing being determined based on SFN timing) when a base station is synchronized to GNSS time, according to some aspects. For example, the DRX pattern of example diagram 1030 may correspond to the DFN timing of direct frame 930 of fig. 9A when the base station is synchronized to GNSS time. The DRX pattern in fig. 10B includes DRX cycles (such as DRX cycles 1036 and 1038) and begins after an offset duration 1034 from a reference time 1032 that is based on DFN timing (which is determined based on SFN timing). Fig. 10B illustrates an on duration 1046 of DRX cycle 1036 having an on duration length 1042 and an off duration 1048 of DRX cycle 1036 having an off duration length 1044. Similarly, fig. 10B further illustrates an on duration 1050 of DRX cycle 1038 and an off duration 1052 of DRX cycle 1038. Because the base station is synchronized to the GNSS time in fig. 10B, the DFN timing based on the SFN timing and used to configure the exemplary DRX mode in fig. 10B is the same as the DFN timing based on the GNSS and used to configure the exemplary DRX mode in fig. 10A. Thus, the example DRX pattern in fig. 10A (or at least the on duration 1016 of the DRX cycle 1006) may fully (or substantially) overlap with the example DRX pattern in fig. 10B (or at least the on duration 1046 of the DRX cycle 1036). In an aspect, the offset duration 1034 may be calculated based on equation (1) discussed above, where the DFN value may correspond to a first direct frame in the DRX cycle 1036, the subframe number may correspond to a subframe within the first direct frame in the DRX cycle 1036 in which the DRX cycle 1036 begins, and the duration of the side link DRX cycle may correspond to the duration of the DRX cycle 1036.

Fig. 10C is an example diagram 1060 illustrating an example DRX mode configured based on DFN timing (the DFN timing is determined based on SFN timing) when the base station is not synchronized to GNSS time, according to some aspects. For example, the DRX pattern of example diagram 1060 may correspond to the DFN timing of the direct frame 980 of fig. 9B when the base station is not synchronized to GNSS time. The DRX pattern in fig. 10C includes DRX cycles (such as DRX cycles 1066 and 1068) and begins after an offset duration 1064 from a reference time 1062 based on the DFN timing (which is determined based on the SFN timing). Fig. 10C shows an on duration 1076 of the DRX cycle 1066 having an on duration length 1072 and an off duration 1078 of the DRX cycle 1066 having an off duration length 1074. Similarly, fig. 10C further illustrates an on duration 1080 of the DRX cycle 1068 and an off duration 1082 of the DRX cycle 1068. Because the base station is not synchronized to GNSS time in fig. 10C, the DFN timing used to configure the exemplary DRX mode in fig. 10C is not exactly the same or similar to the DFN timing used to configure the exemplary DRX mode in fig. 10A. Thus, the exemplary DRX pattern in fig. 10A (or at least the on duration 1016 of the DRX cycle 1006) does not substantially overlap the exemplary DRX pattern in fig. 10C (or at least the on duration 1076 of the DRX cycle 1036). The timing of the exemplary DRX pattern in fig. 10C may not be substantially aligned with the timing of the exemplary DRX pattern in fig. 10A, although the on-durations of the two DRX patterns substantially overlap each other. In an aspect, the offset duration 1064 may be calculated based on equation (1) discussed above, where the DFN value may correspond to a first direct frame in the DRX cycle 1066, the subframe number may correspond to a subframe within the first direct frame in the DRX cycle 1066 in which the DRX cycle 1066 begins, and the duration of the side link DRX cycle may correspond to the duration of the DRX cycle 1066.

In an aspect, if the boundary of the system frame is not aligned with the boundary of the GNSS based direct frame, the UE may not utilize at least a portion of the first frame corresponding to the first DFN based on DFN timing and/or at least a portion of the last frame corresponding to the last DFN based on DFN timing for side link transmission. As discussed above, if the base station is not synchronized to GNSS time, for example, the boundaries of the system frame may not be aligned with the boundaries of the GNSS based direct frame. For example, if the boundaries of the system frame are not aligned with the boundaries of the GNSS based direct frame, the frame boundaries of the SFN timing based direct frame may not be aligned with the boundaries of the GNSS based direct frame either. Therefore, when the direct frame is based on such SFN timing, it may be beneficial to skip side chain transmissions with the first portion of the direct frame and/or the last portion of the direct frame. On the other hand, even if the boundary of the system frame is not aligned with the boundary of the GNSS-based direct frame, the UE may receive side link communication or monitor side link communication on the first frame corresponding to the first DFN and/or the last frame corresponding to the last DFN.

Fig. 11A is an example diagram 1100 illustrating direct frames, system frames, and GNSS-based direct frames based on DFN timing (the DFN timing being determined based on SFN timing) when a base station is not synchronized to GNSS time, in accordance with some aspects. In the example of FIG. 11A, because the base station is not synchronized to GNSS time, the frame boundaries of the GNSS-based direct frame 1110 are not aligned with the frame boundaries of the system frame 1120 associated with the base station. Thus, in fig. 11A, the DFN timing determined based on the SFN timing associated with the system frame 1120 may cause the frame boundary (e.g., using an offset value) of the direct frame 1130 based on the SFN timing to be misaligned with the boundary of the direct frame 1110 based on the GNSS. As shown in fig. 11B, although DFNs 0,1, … n of the SFN timing based direct frame 1130 substantially overlap DFNs 0,1, … n, respectively, of the GNSS based direct frame 1110, the SFN timing based direct frame 1130 begins slightly later than the GNSS based direct frame 1110. In fig. 11A, the last portion 1140 of the DFN of the direct frame 1130 does not overlap with any of the GNSS-based direct frames 1110, and thus, in an aspect, the UE may refrain from transmitting-side link communication during the last portion 1140 of the DFN of the direct frame 1130.

Fig. 11B is an example diagram 1150 illustrating direct frames, system frames, and GNSS-based direct frames based on DFN timing (the DFN timing being determined based on SFN timing) when a base station is not synchronized to GNSS time, in accordance with some aspects. In the example of fig. 11B, because the base station is not synchronized to GNSS time, the frame boundaries of the GNSS based direct frame 1160 are not aligned with the frame boundaries of the system frame 1170 associated with the base station. Thus, in fig. 11B, the DFN timing determined based on the SFN timing associated with the system frame 1170 may cause the frame boundary (e.g., using an offset value) of the direct frame 1180 based on the SFN timing to be misaligned with the boundary of the direct frame 1160 based on the GNSS. As shown in fig. 11B, although the DFNs 0,1, … n of the SFN timing based direct frame 1180 substantially overlap the DFNs 0,1, … n of the GNSS based direct frame 1160, respectively, the SFN timing based direct frame 1180 begins slightly earlier than the GNSS based direct frame 1160. In fig. 11B, the first portion 1190 of the DFN 0 of the direct frame 1180 does not overlap with any of the GNSS-based direct frames 1160, and thus, in an aspect, the UE may refrain from transmitting-side link communication during the first portion 1190 of the DFN 0 of the direct frame 1180.

In an aspect, a base station may transmit a skip indicator to a UE indicating that utilization-side link communication is to be suppressed for at least a portion of a first frame corresponding to a first DFN based on DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on DFN timing. When the UE receives the skip indicator, the UE may refrain from transmitting side link communications to the second UE during at least the portion of the first frame and/or at least the portion of the last frame based on the skip indicator. In an aspect, the base station may transmit a skip indicator to the UE when the base station determines that the base station is not synchronized to GNSS time.

In an aspect, the skip indicator may include: a first number of time slots in the first frame to be skipped for side link communications and/or a second number of time slots in the last frame to be skipped for side link communications. For example, based on the skip indicator, the UE may skip the first few slots in the first frame for transmission side link communications and/or may skip the last few slots in the last frame for transmission side link communications.

Fig. 12 is an example flow diagram 1200 illustrating interactions between a first UE 1202, a second UE 1204, and a base station 1206, according to some aspects. In fig. 12, in an aspect, at 1212, the base station 1206 may determine a DFN indicator and transmit the DFN indicator to the first UE 1202, wherein the DFN indicator may include one or more of: offset values indicating the difference between the DFN timing and the SFN timing associated with the base station, the DFN timing, and the GNSS time. In this regard, at 1214, the first UE 1202 may determine the DFN timing based on the DFN indicator. In another aspect, the first UE 1202 may determine the DFN timing on its own without receiving or relying on the DFN indicator at 1214. For example, the first UE 1202 may determine a GNSS time and may determine a DFN timing based on the GNSS time. At 1216, the first UE 1202 may configure a side link DRX mode using one or more side link DRX parameters based on the DFN timing. At 1220, the first UE 1202 may perform side link communication with the second UE 1204 during an on duration of a side link DRX cycle in side link DRX mode according to the one or more side link DRX parameters.

Fig. 13 is a block diagram illustrating an example of a hardware implementation of a UE 1300 employing a processing system 1314. For example, UE 1300 may be a User Equipment (UE) as described in any one or more of fig. 1, fig. 2, and/or fig. 3.

The UE 1300 may be implemented with a processing system 1314 including one or more processors 1304. Examples of processor 1304 include microprocessors, microcontrollers, digital Signal Processors (DSPs), field Programmable Gate Arrays (FPGAs), programmable Logic Devices (PLDs), state machines, gate logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionalities described throughout this disclosure. In various examples, UE 1300 may be configured to perform any one or more of the functions described herein. That is, the processor 1304 as utilized in the UE 1300 may be used to implement any one or more of the processes and procedures described below and illustrated in fig. 14-15.

In this example, the processing system 1314 may be implemented with a bus architecture, represented generally by the bus 1302. The bus 1302 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1314 and the overall design constraints. The bus 1302 communicatively couples various circuitry including one or more processors (represented generally by the processor 1304), memory 1305, and computer-readable media (represented generally by the computer-readable storage medium 1306). The bus 1302 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. Bus interface 1308 provides an interface between bus 1302 and transceiver 1310. The transceiver 1310 provides a communication interface or means for communicating with various other apparatus over a transmission medium. Depending on the nature of the equipment, a user interface 1312 (e.g., keypad, display, speaker, microphone, joystick) may also be provided. Of course, such user interfaces 1312 are optional and may be omitted in some examples (such as base stations).

In some aspects of the disclosure, the processor 1304 can include DFN management circuitry 1340 configured for various functions including, for example, determining DFN timing. For example, DFN management circuitry 1340 may be configured to implement one or more of the functions described below with respect to fig. 14 and 15, including, for example, blocks 1402 and 1508.

In some aspects, DFN management circuitry 1340 may be configured for various functions including, for example, receiving DFN indicators from a base station. For example, DFN management circuitry 1340 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1502.

In some aspects, DFN management circuitry 1340 may be configured for various functions including, for example, determining Global Navigation Satellite System (GNSS) time. For example, DFN management circuitry 1340 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1506.

In some aspects of the disclosure, the processor 1304 can include DRX management circuitry 1342 configured for various functions including configuring a side link Discontinuous Reception (DRX) mode, e.g., using one or more DRX parameters based on DFN timing. For example, DRX management circuitry 1342 may be configured to implement one or more of the functions described below with respect to fig. 14 and 15, including, for example, blocks 1404 and 1510.

In some aspects of the disclosure, the processor 1304 may include communication management circuitry 1344 configured for various functions including, for example, performing side-link communication with the second UE during an on-duration of a side-link DRX cycle in a side-link DRX mode according to the one or more side-link DRX parameters. For example, the communication management circuitry 1344 may be configured to implement one or more of the functions described below with respect to fig. 14 and 15, including, for example, blocks 1406 and 1520.

In some aspects, the communication management circuitry 1344 may be configured for various functions including, for example, receiving a GNSS synchronization indicator from a base station indicating whether the base station is synchronized to GNSS time. For example, the communication management circuitry 1344 may be configured to implement one or more of the functions described below with respect to fig. 15, including for example block 1504.

In some aspects, the communication management circuitry 1344 may be configured for various functions including, for example, refraining from transmitting side-link communications to the second UE during at least a portion of a first frame corresponding to a first DFN based on DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on DFN timing if the GNSS synchronization indicator indicates that the base station is not synchronized to GNSS time. For example, the communication management circuitry 1344 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1512.

In some aspects, the communication management circuitry 1344 may be configured for various functions including performing side link communication with a second using at least one of the first frame or the last frame, for example, if the GNSS synchronization indicator indicates that the base station is synchronized to GNSS time. For example, the communication management circuitry 1344 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1514.

In some aspects, the communication management circuitry 1344 may be configured for various functions including, for example, receiving a skip indicator from a base station indicating that transmission side link communication is to be suppressed for at least a portion of a first frame corresponding to a first DFN based on DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on DFN timing. For example, the communication management circuitry 1344 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1516.

In some aspects, the communication management circuitry 1344 may be configured for various functions including refraining from transmitting side link communications with the second UE during at least the portion of the first frame and/or at least the portion of the last frame, e.g., based on the skip indicator. For example, the communication management circuitry 1344 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1518.

The processor 1304 is responsible for managing the bus 1302 and general processing, including the execution of software stored on the computer-readable storage medium 1306. The software, when executed by the processor 1304, causes the processing system 1314 to perform the various functions described infra for any particular apparatus. The computer-readable storage medium 1306 and memory 1305 may also be used for storing data that is manipulated by the processor 1304 when executing software.

One or more processors 1304 in the processing system may execute software. Software should be construed broadly to mean instructions, instruction sets, code segments, program code, programs, subroutines, software modules, applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether described in software, firmware, middleware, microcode, hardware description language, or other terminology. The software may reside on a computer readable storage medium 1306. The computer-readable storage medium 1306 may be a non-transitory computer-readable storage medium. By way of example, non-transitory computer-readable storage media include magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips), optical disks (e.g., compact Disk (CD) or Digital Versatile Disk (DVD)), smart cards, flash memory devices (e.g., card, stick, or key drive), random Access Memory (RAM), read Only Memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically Erasable PROM (EEPROM), registers, removable disk, and any other suitable medium for storing software and/or instructions that can be accessed and read by a computer. The computer-readable storage medium 1306 may reside in the processing system 1314, external to the processing system 1314, or distributed across multiple entities including the processing system 1314. The computer-readable storage medium 1306 may be implemented in a computer program product. By way of example, a computer program product may include a computer readable storage medium in an encapsulating material. Those skilled in the art will recognize how to best implement the described functionality presented throughout this disclosure depending on the particular application and overall design constraints imposed on the overall system.

In some aspects of the disclosure, the computer-readable storage medium 1306 may include DFN management software/instructions 1360 configured for various functions including, for example, determining DFN timing. For example, DFN management software/instructions 1360 may be configured to implement one or more of the functions described below with respect to fig. 14 and 15, including, for example, blocks 1402 and 1508.

In some aspects of the disclosure, the DFN management software/instructions 1360 may be configured for various functions including, for example, receiving DFN indicators from a base station. For example, the DFN management software/instructions 1360 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1502.

In some aspects, the DFN management software/instructions 1360 may be configured for various functions including, for example, determining GNSS time. For example, DFN management software/instructions 1360 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1506.

In some aspects of the disclosure, the computer-readable storage medium 1306 may include DRX management software/instructions 1362 configured for various functions including, for example, configuring a side link DRX mode using one or more side link DRX parameters based on DFN timing. For example, DRX management software/instructions 1362 may be configured to implement one or more of the functions described below with respect to fig. 14 and 15, including, for example, blocks 1404 and 1510.

In some aspects of the disclosure, the computer-readable storage medium 1306 may include communication management software/instructions 1364 configured for various functions including, for example, performing side-link communication with the second UE during an on-duration of a side-link DRX cycle in a side-link DRX mode according to the one or more side-link DRX parameters. For example, the communication management software/instructions 1364 may be configured to implement one or more of the functions described below with respect to fig. 14 and 15, including, for example, blocks 1406 and 1520.

In some aspects, the communication management software/instructions 1364 may be configured for various functions including, for example, receiving a GNSS synchronization indicator from a base station indicating whether the base station is synchronized to GNSS time. For example, the communication management software/instructions 1364 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1504.

In some aspects, the communication management software/instructions 1364 may be configured for various functions including, for example, refraining from transmitting side link communications to the second UE during at least a portion of a first frame corresponding to a first DFN based on DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on DFN timing if the GNSS synchronization indicator indicates that the base station is not synchronized to GNSS time. For example, the communication management software/instructions 1364 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1512.

In some aspects, the communication management software/instructions 1364 may be configured for various functions including, for example, performing side link communication with the second UE with at least one of the first frame or the last frame if the GNSS synchronization indicator indicates that the base station is synchronized to GNSS time. For example, the communication management software/instructions 1364 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1514.

In some aspects, the communication management software/instructions 1364 may be configured for various functions including, for example, receiving a skip indicator from a base station indicating that transmission side link communication is to be suppressed for at least a portion of a first frame corresponding to a first DFN based on DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on DFN timing. For example, the communication management software/instructions 1364 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1516.

In some aspects, the communication management software/instructions 1364 may be configured for various functions including suppressing transmission of sidelink communications with a second UE during at least the portion of the first frame and/or at least the portion of the last frame, e.g., based on the skip indicator. For example, the communication management software/instructions 1364 may be configured to implement one or more of the functions described below with respect to fig. 15, including, for example, block 1518.

Fig. 14 is a flow chart illustrating an exemplary process 1400 for wireless communication in accordance with some aspects of the present disclosure. As described below, some or all of the illustrated features may be omitted from a particular implementation within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, process 1400 may be performed by UE 1300 illustrated in fig. 13. In some examples, process 1400 may be performed by any suitable device or means for performing the functions or algorithms described below.

At block 1402, the ue 1300 may determine DFN timing. For example, DFN management circuitry 1340 shown and described above in connection with fig. 13 may provide means for determining DFN timing.

At block 1404, the ue 1300 may configure a side link DRX mode using one or more DRX parameters based on the DFN timing. For example, the DRX management circuitry 1342 shown and described above in connection with fig. 13 may provide means for configuring the side link DRX mode.

In an aspect, the one or more side link DRX parameters may include at least one of: an on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for initiating the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode. In an aspect, the offset duration may be based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and a duration of a side link DRX cycle. In an aspect, the offset duration may be based on a remainder determined by dividing a sum of the subframe number and a product of the DFN and 10 by a duration of a side link DRX cycle.

In block 1406, the UE 1300 may perform side link communication with a second UE during an on duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters. For example, the communication management circuitry 1344 shown and described above in connection with fig. 13 may provide means for performing side link communication.

Fig. 15 is a flow chart illustrating an exemplary process 1500 for wireless communication in accordance with some aspects of the present disclosure. As described below, some or all of the illustrated features may be omitted from a particular implementation within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the process 1500 may be performed by the UE 1300 illustrated in fig. 13. In some examples, process 1500 may be performed by any suitable device or means for performing the functions or algorithms described below.

In block 1502, in an aspect, the UE 1300 may receive a DFN indicator from a base station. For example, DFN management circuitry 1340 shown and described above in connection with fig. 13 may provide means for receiving DFN indicators.

At block 1504, in an aspect, the UE 1300 may receive a GNSS synchronization indicator from a base station indicating whether the base station is synchronized to GNSS time. For example, the communication management circuitry 1344 shown and described above in connection with fig. 13 may provide means for receiving a GNSS synchronization indicator.

At block 1506, in an aspect, the UE 1300 may determine GNSS time. For example, the DFN management circuitry 1340 shown and described above in connection with fig. 13 may provide a means for determining GNSS time.

At block 1508, the ue 1300 may determine DFN timing. For example, DFN management circuitry 1340 shown and described above in connection with fig. 13 may provide means for determining DFN timing.

In an aspect, determining the DFN timing at block 1508 may include determining the DFN timing based on the GNSS time determined at block 1506.

In an aspect, determining the DFN timing at block 1508 may include determining the DFN timing based on the DFN indicator received at block 1502. In an aspect, the DFN indicator may include at least one of: offset values indicating the difference between DFN timing and SFN timing associated with the base station, DFN timing, or GNSS time. In an aspect, at least one of the offset value or the DFN timing may be based on GNSS time. In an aspect, the DFN indicator may include an offset value indicating a difference between the DFN timing and the SFN timing associated with the base station, and the offset value may be based on GNSS time. In an aspect, the DFN timing may be based on GNSS time. In an aspect, the DFN indicator may be received via at least one of SIB, RRC message, PBCH, or MAC-CE.

At block 1510, the ue 1300 may configure a side link DRX mode using the one or more side link DRX parameters based on the DFN timing. For example, the DRX management circuitry 1342 shown and described above in connection with fig. 13 may provide means for configuring the side link DRX mode.

In an aspect, the one or more side link DRX parameters may include at least one of: an on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for initiating the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode. In an aspect, the offset duration may be based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and a duration of a side link DRX cycle. In an aspect, the offset duration may be based on a remainder determined by dividing a sum of the subframe number and a product of the DFN and 10 by a duration of a side link DRX cycle.

At block 1512, in an aspect, the UE 1300 may refrain from transmitting side link communications to the second UE during at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing if the GNSS synchronization indicator indicates that the base station is not synchronized to GNSS time. For example, the communication management circuitry 1344 shown and described above in connection with fig. 13 may provide means for suppressing transmit side link communication during at least the portion of the first frame and/or during at least the portion of the last frame.

At block 1514, in an aspect, the UE 1300 may utilize at least one of the first frame or the last frame to perform side link communication with a second UE if the GNSS synchronization indicator indicates that the base station is synchronized to GNSS time. For example, the communication management circuitry 1344 shown and described above in connection with fig. 13 may provide means for performing side-link communication utilizing the at least one of the first frame or the last frame.

In an aspect, side-chain communication may be further performed based on the GNSS synchronization indicator.

At block 1516, in an aspect, the UE 1300 may receive a skip indicator from the base station indicating that transmit side link communication is to be suppressed for at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing. For example, the communication management circuitry 1344 shown and described above in connection with fig. 13 may provide means for receiving a skip indicator. In an aspect, the skip indicator may be received when the base station is not synchronized to GNSS time. In an aspect, the skip indicator may indicate at least one of: a first number of time slots in the first frame to be skipped for side link communications or a second number of time slots in the last frame to be skipped for side link communications.

At block 1518, in an aspect, the UE 1300 may refrain from transmitting side-chain communications with a second UE during the at least one of the portion of the first frame or the portion of the last frame based on the skip indicator. For example, the communication management circuitry 1344 shown and described above in connection with fig. 13 may provide means for suppressing transmit side link communication during at least the portion of the first frame and/or during at least the portion of the last frame.

At block 1520, the UE 1300 may perform side link communication with the second UE during an on duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters. For example, the communication management circuitry 1344 shown and described above in connection with fig. 13 may provide means for performing side link communication.

In one configuration, the UE 1300 for wireless communication includes: means for determining DFN timing; means for configuring a side link DRX mode using one or more side link DRX parameters based on the DFN timing; and means for performing side link communication with the second UE during an on-duration of a side link DRX cycle in the side link DRX mode in accordance with the one or more side link DRX parameters.

In an aspect, the UE 1300 may further include means for determining GNSS time. In an aspect, the UE 1300 may further include means for receiving the DFN indicator from the base station. In an aspect, the UE 1300 may further include means for receiving a GNSS synchronization indicator from the base station indicating whether the base station is synchronized to GNSS time. In an aspect, the UE 1300 may further include means for refraining from transmitting the sidelink communication to the second UE during at least a portion of a first frame corresponding to a first DFN based on the DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on the DFN timing if the GNSS synchronization indicator indicates that the base station is not synchronized to GNSS time; and means for performing side link communication with the second UE using at least one of the first frame or the last frame if the GNSS synchronization indicator indicates that the base station is synchronized to GNSS time. In an aspect, the UE 1300 may further include: means for receiving a skip indicator from a base station, the skip indicator indicating that transmission of the side link communication is to be suppressed for at least a portion of a first frame corresponding to a first DFN based on the DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on the DFN timing; and means for refraining from transmitting side link communications with a second UE during at least the portion of the first frame and/or at least the portion of the last frame based on the skip indicator.

In one aspect, the foregoing means may be the processor(s) 1304 shown in fig. 13 configured to perform the functions recited by the foregoing means. In another aspect, the foregoing apparatus may be circuitry or any equipment configured to perform the functions recited by the foregoing apparatus.

Of course, in the above examples, the circuitry included in the processor 1304 is provided by way of example only, and other means for performing the described functions may be included within aspects of the disclosure, including but not limited to instructions stored in the computer-readable storage medium 1306, or any other suitable apparatus or means described in any of fig. 1, 2, 4, 8, and/or 12 and utilizing, for example, the processes and/or algorithms described herein with respect to fig. 14 and/or 15.

Fig. 16 is a conceptual diagram illustrating an example of a hardware implementation of an exemplary base station 1600 employing a processing system 1614. According to various aspects of the disclosure, an element, or any portion of an element, or any combination of elements, may be implemented with a processing system 1614 that includes one or more processors 1604. For example, base station 1600 may be a User Equipment (UE) as illustrated in any one or more of fig. 1, 2, and/or 3.

The processing system 1614 may be substantially the same as the processing system 1314 illustrated in fig. 13, including a bus interface 1608, a bus 1602, a memory 1605, a processor 1604, and a computer-readable storage medium 1606. In addition, base station 1600 may include a user interface 1612 and transceiver 1610 substantially similar to those described above in fig. 13. That is, the processor 1604 as utilized in the base station 1600 may be used to implement any one or more of the processes described below and illustrated in fig. 17-18. Of course, such user interfaces 1612 are optional and may be omitted in some examples (such as a base station).

In some aspects of the disclosure, the processor 1604 may include timing management circuitry 1640 configured for various functions, including, for example, determining a DFN indicator. For example, timing management circuitry 1640 may be configured to implement one or more of the functions described below with respect to fig. 17 and 18, including, for example, blocks 1702 and 1802.

In some aspects, the timing management circuitry 1640 may be configured for various functions including, for example, determining that a base station is not synchronized to GNSS time. For example, timing management circuitry 1640 may be configured to implement one or more of the functions described below with respect to fig. 18, including, for example, block 1806.

In some aspects of the disclosure, the processor 1604 may include communication management circuitry 1642 configured for various functions including, for example, transmitting the DFN indicator to a first User Equipment (UE) to cause the first UE to configure a side link DRX mode using one or more side link DRX parameters based on a DFN timing based on the DFN indicator. For example, the communication management circuitry 1642 may be configured to implement one or more of the functions described below with respect to fig. 17 and 18, including, for example, blocks 1704 and 1804.

In some aspects, the communication management circuitry 1642 may be configured for various functions including, for example, transmitting a GNSS synchronization indicator indicating whether the base station is synchronized to GNSS time. For example, the communication management circuitry 1642 may be configured to implement one or more of the functions described below with respect to fig. 18, including, for example, block 1808.

In some aspects, the communication management circuitry 1642 may be configured for various functions including, for example, transmitting a skip indicator indicating that the side link communication is to be suppressed for at least a portion of a first frame corresponding to a first DFN based on the DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on the DFN timing, such that the first UE suppresses transmission of the side link communication to the second UE during at least the portion of the first frame and/or at least the portion of the last frame based on the skip indicator. For example, the communication management circuitry 1642 may be configured to implement one or more of the functions described below with respect to fig. 18, including, for example, block 1810.

In some aspects of the disclosure, the computer-readable storage medium 1306 may include timing management software/instructions 1660 configured for various functions, including, for example, determining DFN indicators. For example, timing management software/instructions 1660 may be configured to implement one or more functions described below with respect to fig. 17 and 18, including, for example, blocks 1702 and 1802.

In some aspects, the timing management software/instructions 1660 may be configured for various functions including, for example, determining that a base station is not synchronized to GNSS time. For example, timing management software/instructions 1660 may be configured to implement one or more functions described below with respect to fig. 18, including, for example, block 1806.

In some aspects of the disclosure, the processor-readable storage medium 1306 may include communication management software/instructions 1662 configured for various functions including, for example, transmitting the DFN indicator to a first User Equipment (UE) to cause the first UE to configure a side link DRX mode using one or more DRX parameters based on a DFN timing based on the DFN indicator. For example, the communication management software/instructions 1662 may be configured to implement one or more of the functions described below with respect to fig. 17 and 18, including, for example, blocks 1704 and 1804.

In some aspects, the communication management software/instructions 1662 may be configured for various functions including, for example, transmitting a GNSS synchronization indicator indicating whether the base station is synchronized to GNSS time. For example, the communication management software/instructions 1662 may be configured to implement one or more functions described below with respect to fig. 18, including, for example, block 1808.

In some aspects, the communication management software/instructions 1662 may be configured for various functions including, for example, transmitting a skip indicator indicating that the side link communication is to be suppressed from being transmitted for at least a portion of a first frame corresponding to a first DFN based on the DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on the DFN timing, such that the first UE suppresses the side link communication from being transmitted to the second UE during at least the portion of the first frame and/or at least the portion of the last frame based on the skip indicator. For example, the communication management software/instructions 1662 may be configured to implement one or more functions described below with respect to fig. 18, including, for example, block 1810.

Fig. 17 is a flow chart illustrating an exemplary process 1700 for wireless communication in accordance with some aspects of the present disclosure. As described below, some or all of the illustrated features may be omitted from a particular implementation within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the process 1700 may be performed by the base station 1600 illustrated in fig. 16. In some examples, the process 1700 may be performed by any suitable device or means for performing the functions or algorithms described below.

At block 1702, the base station 1600 may determine a DFN indicator. For example, timing management circuitry 1640 shown and described above in connection with fig. 16 may provide means for determining DFN indicators.

At block 1704, the base station 1600 may transmit the DFN indicator to a first User Equipment (UE) to cause the first UE to configure a side link DRX mode using one or more side link DRX parameters based on a DFN timing based on the DFN indicator. For example, the communication management circuitry 1642 shown and described above in connection with fig. 16 may provide means for transmitting the DFN indicator.

In an aspect, the one or more side link DRX parameters may include at least one of: an on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for initiating the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode. In an aspect, the offset duration may be based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and a duration of a side link DRX cycle. In an aspect, the offset duration may be based on a remainder determined by dividing a sum of the subframe number and a product of the DFN and 10 by a duration of a side link DRX cycle.

Fig. 18 is a flow chart illustrating an exemplary process 1800 for wireless communication in accordance with some aspects of the present disclosure. As described below, some or all of the illustrated features may be omitted from a particular implementation within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, process 1800 may be performed by base station 1600 illustrated in fig. 16. In some examples, process 1800 may be performed by any suitable device or means for performing the functions or algorithms described below.

At block 1802, the base station 1600 may determine a DFN indicator. For example, timing management circuitry 1640 shown and described above in connection with fig. 16 may provide means for determining DFN indicators.

At block 1804, the base station 1600 may transmit the DFN indicator to a first User Equipment (UE) to cause the first UE to configure a side link DRX mode using one or more side link DRX parameters based on a DFN timing based on the DFN indicator. For example, the communication management circuitry 1642 shown and described above in connection with fig. 16 may provide means for transmitting the DFN indicator. In an aspect, side link communication between the first UE and the second UE may be performed during an on-duration of a side link DRX cycle in side link DRX mode according to the one or more side link DRX parameters.

In an aspect, the one or more side link DRX parameters may include at least one of: an on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for initiating the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode. In an aspect, the offset duration may be based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and a duration of a side link DRX cycle. In an aspect, the offset duration may be based on a remainder determined by dividing a sum of the subframe number and a product of the DFN and 10 by a duration of a side link DRX cycle.

In an aspect, the DFN indicator may include at least one of: offset values indicating the difference between DFN timing and SFN timing associated with the base station, DFN timing, or GNSS time. In an aspect, determining the DFN indicator at 1802 may include determining at least one of an offset value or DFN timing based on GNSS time. In an aspect, the DFN indicator includes an offset value indicating a difference between DFN timing and SFN timing associated with the base station, and the offset value is based on GNSS time. In an aspect, the DFN timing is based on GNSS time. In an aspect, the DFN indicator may be transmitted via at least one of SIB, RRC message, PBCH, or MAC-CE.

In block 1806, in an aspect, the base station 1600 may determine that the base station is not synchronized to GNSS time. For example, the timing management circuitry 1640 shown and described above in connection with fig. 16 may provide means for determining that a base station is not synchronized to GNSS time.

In block 1808, in an aspect, the base station 1600 may transmit a GNSS synchronization indicator indicating whether the base station is synchronized to GNSS time. For example, the communication management circuitry 1642 shown and described above in connection with fig. 16 may provide means for transmitting GNSS synchronization indicators. In an aspect, side-chain communication may be further performed based on the GNSS synchronization indicator.

At block 1810, in an aspect, the base station 1600 may transmit a skip indicator indicating that the side link communication is to be suppressed from being transmitted for at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing to cause the first UE to suppress transmission of the side link communication to the second UE during the at least one of the portion of the first frame or the portion of the last frame based on the skip indicator. For example, the communication management circuitry 1642 shown and described above in connection with fig. 16 may provide means for transmitting the skip indicator. In an aspect, the skip indicator may be transmitted in response to determining that the base station is not synchronized to GNSS time at block 1806. In an aspect, the skip indicator may indicate at least one of: a first number of time slots in the first frame to be skipped for side link communications or a second number of time slots in the last frame to be skipped for side link communications.

In one configuration, a base station 1600 for wireless communications includes: means for determining a DFN indicator; and means for transmitting the DFN indicator to a first User Equipment (UE) to cause the first UE to configure a side link DRX mode using a side link DRX parameter based on a DFN timing, the DFN timing being based on the DFN indicator. In an aspect, the base station 1600 may further comprise means for transmitting a GNSS synchronization indicator indicating whether the base station is synchronized to GNSS time. In an aspect, base station 1600 may further include means for transmitting a skip indicator indicating that the side link communication is to be suppressed from being transmitted for at least a portion of a first frame corresponding to a first DFN based on the DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on the DFN timing such that the first UE suppresses the side link communication from being transmitted to the second UE during at least the portion of the first frame and/or at least the portion of the last frame based on the skip indicator. In an aspect, the base station 1600 may further comprise means for determining that the base station is not synchronized to GNSS time.

In one aspect, the foregoing means may be the processor(s) 1604 shown in fig. 16 configured to perform the functions recited by the foregoing means. In another aspect, the foregoing apparatus may be circuitry or any equipment configured to perform the functions recited by the foregoing apparatus.

Of course, in the above examples, the circuitry included in the processor 1604 is provided by way of example only, and other means for performing the described functions may be included within aspects of the disclosure, including but not limited to instructions stored in the computer-readable storage medium 1306, or any other suitable apparatus or means described in any of fig. 1, 2, 4, 8, and/or 12 and utilizing, for example, the processes and/or algorithms described herein with respect to fig. 17 and/or 18. .

The following provides an overview of several aspects of the disclosure:

aspect 1: a method of wireless communication by a User Equipment (UE), comprising: determining a Direct Frame Number (DFN) timing; configuring a side link Discontinuous Reception (DRX) mode using one or more DRX parameters based on the DFN timing; and performing side link communication with the second UE during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

Aspect 2: the method of aspect 1, further comprising: determining a Global Navigation Satellite System (GNSS) time; and determining the DFN timing based on the GNSS time.

Aspect 3: the method of aspect 1, further comprising: receiving a DFN indicator from a base station; and determining the DFN timing based on the DFN indicator.

Aspect 4: the method of aspect 3, wherein the DFN indicator includes at least one of: an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing associated with the base station, the DFN timing, or a Global Navigation Satellite System (GNSS) time.

Aspect 5: the method of aspect 3, wherein the DFN indicator includes an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing associated with the base station, and wherein the offset value is based on Global Navigation Satellite System (GNSS) time.

Aspect 6: the method of aspect 3, wherein the DFN timing is based on Global Navigation Satellite System (GNSS) time.

Aspect 7: the method of any of aspects 3-6, wherein the DFN indicator is received via at least one of: a System Information Block (SIB), a Radio Resource Control (RRC) message, a Physical Broadcast Channel (PBCH), or a medium access control-control element (MAC-CE).

Aspect 8: the method of any one of aspects 1 to 7, further comprising: a GNSS synchronization indicator is received from the base station indicating whether the base station is synchronized to GNSS time, wherein the side link communication is performed further based on the GNSS synchronization indicator.

Aspect 9: the method of aspect 8, further comprising: if the GNSS synchronization indicator indicates that the base station is not synchronized to the GNSS time, refraining from transmitting the sidelink communication to the second UE during at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing; and if the GNSS synchronization indicator indicates that the base station is synchronized to the GNSS time, performing the side link communication with the second UE using at least one of the first frame or the last frame.

Aspect 10: the method of any one of aspects 1 to 9, further comprising: receiving a skip indicator from a base station, the skip indicator indicating that the side link communication is to be suppressed from being transmitted for at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing; and refrain from transmitting the side-chain communication with a second UE during the at least one of the portion of the first frame or the portion of the last frame based on the skip indicator.

Aspect 11: the method of aspect 10, wherein the skip indicator is received when the base station is not synchronized to GNSS time.

Aspect 12: the method of aspects 10 or 11, wherein the skip indicator indicates at least one of: a first number of slots in the first frame to be skipped for the side link communication or a second number of slots in the last frame to be skipped for the side link communication.

Aspect 13: the method of any one of aspects 1 to 12, wherein the one or more side link DRX parameters include at least one of: the on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for starting the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode.

Aspect 14: the method of aspect 13, wherein the offset duration is based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and the duration of the side link DRX cycle.

Aspect 15: the method of aspect 14, wherein the offset duration is based on a remainder determined by dividing a sum of the subframe number and a product of the DFN and 10 by the duration of the side link DRX cycle.

Aspect 16: a User Equipment (UE) for wireless communication, comprising: a transceiver configured to communicate with a radio access network; a memory; and a processor communicatively coupled to the transceiver and the memory, wherein the processor and the memory are configured to perform any of aspects 1-15.

Aspect 17: a UE for wireless communication configured for wireless communication, comprising at least one means for performing any one of aspects 1 to 15.

Aspect 18: a non-transitory processor-readable storage medium having instructions thereon for a UE, wherein the instructions, when executed by processing circuitry, cause the processing circuitry to perform any of aspects 1 to 15.

Aspect 19: a method of wireless communication by a base station, comprising: determining a Direct Frame Number (DFN) indicator; and transmitting the DFN indicator to a first User Equipment (UE) to cause the first UE to configure a side link Discontinuous Reception (DRX) mode using one or more side link DRX parameters based on a DFN timing based on the DFN indicator, wherein side link communication between the first UE and a second UE is performed during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

Aspect 20: the method of claim 19, wherein the DFN indicator includes at least one of: an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing, the DFN timing, or a Global Navigation Satellite System (GNSS) time.

Aspect 21: the method of aspect 20, wherein the DFN indicator includes an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing associated with a base station, and wherein the offset value is based on Global Navigation Satellite System (GNSS) time.

Aspect 22: the method of aspect 20, wherein the DFN timing is based on Global Navigation Satellite System (GNSS) time.

Aspect 23: the method of any of aspects 19 to 22, wherein the DFN indicator is transmitted via at least one of: a System Information Block (SIB), a Radio Resource Control (RRC) message, a Physical Broadcast Channel (PBCH), or a medium access control-control element (MAC-CE).

Aspect 24: the method of any one of aspects 19 to 23, further comprising: transmitting a Global Navigation Satellite System (GNSS) synchronization indicator indicating whether the base station is synchronized to GNSS time, wherein the side link communication is performed further based on the GNSS synchronization indicator.

Aspect 25: the method of any one of aspects 19 to 24, further comprising: the transmit indication is to refrain from transmitting a skip indicator of the side link communication for at least a portion of a first frame corresponding to a first DFN based on the DFN timing and/or at least a portion of a last frame corresponding to a last DFN based on the DFN timing such that the first UE refrains from transmitting the side link communication to the second UE during at least the portion of the first frame and/or at least the portion of the last frame based on the skip indicator.

Aspect 26: the method of aspect 25, further comprising: determining that the base station is not synchronized to a Global Navigation Satellite System (GNSS) time, wherein the skip indicator is transmitted in response to determining that the base station is not synchronized to the GNSS time.

Aspect 27: a method as in aspect 25 or 26, wherein the skip indicator indicates at least one of: a first number of slots in the first frame to be skipped for the side link communication or a second number of slots in the last frame to be skipped for the side link communication.

Aspect 28: the method of any of claims 19 to 27, wherein the one or more side link DRX parameters include at least one of: the on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for starting the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode.

Aspect 29: the method of aspect 28, wherein the offset duration is based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and the duration of the side link DRX cycle.

Aspect 30: the method of claim 29, wherein the offset duration is based on a remainder determined by dividing a sum of the subframe number and a product of the DFN and 10 by the duration of the side link DRX cycle.

Aspect 31: a base station for wireless communication, comprising: a transceiver configured to communicate with a radio access network; a memory; and a processor communicatively coupled to the transceiver and the memory, wherein the processor and the memory are configured to perform any of aspects 19-30.

Aspect 32: a base station for wireless communication configured for wireless communication, comprising at least one apparatus for performing the method of any one of aspects 19 to 30.

Aspect 33: a non-transitory processor-readable storage medium having instructions thereon for a base station, wherein the instructions, when executed by a processing circuit, cause the processing circuit to perform any of aspects 19 to 30.

Several aspects of a wireless communication network have been presented with reference to an exemplary implementation. As will be readily appreciated by those skilled in the art, the various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures, and communication standards.

As an example, various aspects may be implemented within other systems defined by 3GPP, such as Long Term Evolution (LTE), evolved Packet System (EPS), universal Mobile Telecommunications System (UMTS), and/or Global System for Mobile (GSM). The various aspects may also be extended to systems defined by third generation partnership project 2 (3 GPP 2), such as CDMA2000 and/or evolution data optimized (EV-DO). Other examples may be implemented within systems employing IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, ultra Wideband (UWB), bluetooth, and/or other suitable systems. The actual telecommunications standards, network architectures, and/or communication standards employed will depend on the particular application and the overall design constraints imposed on the system.

Within this disclosure, the phrase "exemplary" is used to mean "serving as an example, instance, or illustration. Any implementation or aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term "aspect" does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term "coupled" is used herein to refer to a direct or indirect coupling between two objects. For example, if object a physically contacts object B and object B contacts object C, then objects a and C may still be considered coupled to each other even though they are not in direct physical contact with each other. For example, a first object may be coupled to a second object even though the first object is never in direct physical contact with the second object. The terms "circuitry" and "circuitry" are used broadly and are intended to encompass both hardware implementations of electronic devices and conductors, which, when connected and configured, enable performance of the functions described in this disclosure, without limitation as to the type of electronic circuitry, as well as software implementations of information and instructions, which, when executed by a processor, enable performance of the functions described in this disclosure.

One or more of the components, steps, features, and/or functions illustrated in fig. 1-18 may be rearranged and/or combined into a single component, step, feature, or function, or implemented in several components, steps, or functions. Additional elements, components, steps, and/or functions may also be added without departing from the novel features disclosed herein. The apparatus, devices, and/or components illustrated in fig. 1-18 may be configured to perform one or more methods, features, or steps described herein. The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware.

It will be understood that the specific order or hierarchy of steps in the methods disclosed are illustrations of exemplary processes. Based on design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented, unless specifically recited herein.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". The term "some" means one or more unless specifically stated otherwise. The phrase referring to a list of items "at least one of" refers to any combination of these items, including individual members. As an example, "at least one of a, b, or c" is intended to encompass: a, a; b; c, performing operation; a and b; a and c; b and c; and a, b and c. The elements of the various aspects described throughout this disclosure are all structural and functional equivalents that are presently or later to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No element of a claim should be construed under the specification of 35u.s.c. ≡112 (f) unless the element is explicitly recited using the phrase "means for … …" or in the case of method claims the element is recited using the phrase "step for … …".

Claims (29)

1. A method of wireless communication by a User Equipment (UE), comprising:

determining a Direct Frame Number (DFN) timing;

configuring a side link Discontinuous Reception (DRX) mode using one or more DRX parameters based on the DFN timing; and

side link communication with the second UE is performed during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

2. The method of claim 1, further comprising:

determining a Global Navigation Satellite System (GNSS) time; and

the DFN timing is determined based on the GNSS time.

3. The method of claim 1, further comprising:

receiving a DFN indicator from a base station; and

the DFN timing is determined based on the DFN indicator.

4. The method of claim 3, wherein the DFN indicator comprises at least one of:

an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing associated with the base station,

the DFN timing, or

Global Navigation Satellite System (GNSS) time.

5. The method of claim 3, wherein the DFN indicator includes an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing associated with the base station, and

Wherein the offset value is based on Global Navigation Satellite System (GNSS) time.

6. The method of claim 3, wherein the DFN timing is based on Global Navigation Satellite System (GNSS) time.

7. The method of claim 3, wherein the DFN indicator is received via at least one of: a System Information Block (SIB), a Radio Resource Control (RRC) message, a Physical Broadcast Channel (PBCH), or a medium access control-control element (MAC-CE).

8. The method of claim 1, further comprising:

a GNSS synchronization indicator is received from a base station indicating whether the base station is synchronized to GNSS time,

wherein the side chain communication is further performed based on the GNSS synchronization indicator.

9. The method of claim 8, further comprising:

if the GNSS synchronization indicator indicates that the base station is not synchronized to the GNSS time, refraining from transmitting the side link communication to the second UE during at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing; and

the side link communication with the second UE is performed with at least one of the first frame or the last frame if the GNSS synchronization indicator indicates that the base station is synchronized to the GNSS time.

10. The method of claim 1, further comprising:

receiving a skip indicator from a base station, the skip indicator indicating that the side link communication is to be suppressed from being transmitted for at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing; and

based on the skip indicator, refraining from transmitting the side link communication with the second UE during the at least one of the portion of the first frame or the portion of the last frame.

11. The method of claim 10, wherein the skip indicator is received when the base station is not synchronized to GNSS time.

12. The method of claim 10, wherein the skip indicator indicates at least one of:

a first number of time slots in the first frame to be skipped for the side link communication, or

A second number of time slots in the last frame to be skipped for the side link communication.

13. The method of claim 1, wherein the one or more side link DRX parameters comprise at least one of: the on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for starting the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode.

14. The method of claim 13, wherein the offset duration is based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and the duration of the side link DRX cycle.

15. The method of claim 14, wherein the offset duration is based on a remainder determined by dividing a sum of the subframe number and a product of the DFNs and 10 by the duration of the side link DRX cycle.

16. A User Equipment (UE) for wireless communication, comprising:

at least one processor;

a transceiver communicatively coupled to the at least one processor; and

a memory communicatively coupled to the at least one processor,

wherein the at least one processor is configured to:

determining a Direct Frame Number (DFN) timing;

configuring a side link Discontinuous Reception (DRX) mode using one or more DRX parameters based on the DFN timing; and

the transceiver is used to perform side link communication with a second UE during an on duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

17. A method of wireless communication by a base station, comprising:

Determining a Direct Frame Number (DFN) indicator; and

transmitting the DFN indicator to a first User Equipment (UE) to cause the first UE to configure a side link Discontinuous Reception (DRX) mode using one or more DRX parameters based on a DFN timing, the DFN timing being based on the DFN indicator,

wherein side link communication between the first UE and a second UE is performed during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.

18. The method of claim 17, wherein the DFN indicator comprises at least one of:

an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing,

the DFN timing, or

Global Navigation Satellite System (GNSS) time.

19. The method of claim 17, wherein the DFN indicator includes an offset value indicating a difference between the DFN timing and a System Frame Number (SFN) timing associated with the base station, and

wherein the offset value is based on Global Navigation Satellite System (GNSS) time.

20. The method of claim 17, wherein the DFN timing is based on Global Navigation Satellite System (GNSS) time.

21. The method of claim 17, wherein the DFN indicator is transmitted via at least one of: a System Information Block (SIB), a Radio Resource Control (RRC) message, a Physical Broadcast Channel (PBCH), or a medium access control-control element (MAC-CE).

22. The method of claim 17, further comprising:

transmitting a Global Navigation Satellite System (GNSS) synchronization indicator indicating whether the base station is synchronized to GNSS time,

wherein the side chain communication is further performed based on the GNSS synchronization indicator.

23. The method of claim 17, further comprising:

a skip indicator indicating that the side link communication is to be suppressed from being transmitted for at least one of a portion of a first frame corresponding to a first DFN based on the DFN timing or a portion of a last frame corresponding to a last DFN based on the DFN timing is transmitted such that the first UE suppresses the side link communication from being transmitted to the second UE during the at least one of the portion of the first frame or the portion of the last frame based on the skip indicator.

24. The method of claim 23, further comprising:

Determining that the base station is not synchronized to Global Navigation Satellite System (GNSS) time,

wherein the skip indicator is transmitted in response to determining that the base station is not synchronized to the GNSS time.

25. The method of claim 23, wherein the skip indicator indicates at least one of:

a first number of time slots in the first frame to be skipped for the side link communication, or

A second number of time slots in the last frame to be skipped for the side link communication.

26. The method of claim 18, wherein the one or more side link DRX parameters comprise at least one of: the on duration of the side link DRX cycle, an offset duration indicating a delay between a reference time for starting the side link DRX mode and a first instance of the side link DRX cycle, a duration of the side link DRX cycle, or a number of DRX cycles for the side link DRX mode.

27. The method of claim 26, wherein the offset duration is based on a DFN corresponding to the DFN timing, a subframe number of a subframe associated with the DFN, and the duration of the side link DRX cycle.

28. The method of claim 27, wherein the offset duration is based on a remainder determined by dividing a sum of the subframe number and a product of the DFNs and 10 by the duration of the side link DRX cycle.

29. A base station for wireless communication, comprising:

at least one processor;

a transceiver communicatively coupled to the at least one processor; and

a memory communicatively coupled to the at least one processor,

wherein the at least one processor is configured to:

determining a Direct Frame Number (DFN) indicator; and

transmitting the DFN indicator to a first User Equipment (UE) using the transceiver, such that the first UE configures a side link Discontinuous Reception (DRX) mode using one or more DRX parameters based on a DFN timing, the DFN timing being based on the DFN indicator,

wherein side link communication between the first UE and a second UE is performed during an on-duration of a side link DRX cycle in the side link DRX mode according to the one or more side link DRX parameters.