Patent Description:
The present disclosure relates generally to communication systems, and more particularly, to cooperative relay in sidelink networks.

Aspects of wireless communication may comprise direct communication between devices, such as based on sidelink. There exists a need for further improvements in sidelink communication technology.

For example, some aspects of wireless communication include direct communication between devices, such as device-to-device (D2D), vehicle-to-everything (V2X), and the like. There exists a need for further improvements in such direct communication between devices. Improvements related to direct communication between devices may be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

<CIT> discloses a method for wireless data communication comprising: a) providing a wireless network of wireless communication devices comprising a source device, a destination device, and multiple cooperative relay devices, wherein the source device is a mobile device powered by an internal battery, the cooperative relay devices are mobile devices, and the destination device is a stationary device; b) allocating to the source device wireless resources comprising OFDMA time-frequency subchannels; c) adjusting transmit power level at the source device based on channel state information of channels between the source device and the cooperative relay devices; and d) communicating a signal using cooperative relaying from the source device to the destination device via the multiple cooperative relay devices, wherein the cooperative relay devices receive the signal from the source device and transmit the signal using the wireless resources allocated to the source device.

In some wireless communication systems, a base station may provide a user equipment (UE) with access to a core network. In some aspects, the UE may be outside of a coverage area of the base station, which may impede access to the core network from the UE through the base station. In some aspects, a UE may connect to a base station through a relay device, for example, when the UE is out of a coverage area, unable to decode signals from the base station due to interference, or the like. However, uplink coverage through a single relay device between the UE and the base station in a multi-hop scenario may be limited.

It has been found that performance of a user equipment (UE) at cell edges may be significantly improved by employing cooperative sidelink relaying, when direct transmission cannot be successfully pursued between the UE and a serving base station. Sidelink cooperative relay transmission may include synchronous or asynchronous, distributed sidelink relaying of UE sidelink data by multiple UEs configured as relays in a network.

Aspects of the present disclosure provide mechanisms to manage various resources to achieve cooperative sidelink relaying with advantages over standard relay communication systems. For example, the subject technology provides diversity gain and power gain over a single relay scenario with increased reliability and coverage of the relay link to the base station. If the destination is a base station (e.g., gNB), then the subject technology can be used as a technique to improve uplink coverage, albeit at the cost of latency (e.g., over two-hop transmissions).

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus can receive, from a second UE, a groupcast signal comprising a resource allocation assigned to a plurality of sidelink UEs including the first UE. The apparatus also can communicate, with a remote apparatus on a first resource included in the resource allocation, a first relay signal comprising at least a portion of the groupcast signal, in which the first relay signal corresponds to at least a portion of a second relay signal communicated with the remote apparatus on a second resource included in the resource allocation by at least one other sidelink UE of the plurality of sidelink UEs.

In another aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus can determine a resource allocation assigned to a plurality of second UEs for forwarding data between the first UE and a remote apparatus through a cooperative relay with the plurality of second UEs. The apparatus also can transmit, to the plurality of second UEs on a first resource over a sidelink channel, a groupcast signal comprising the resource allocation.

In yet another aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus can receive, from a plurality of first user equipments (UEs), a plurality of relay signals that are cooperatively relayed through respective ones of the plurality of first UEs. The apparatus also can decode each of the plurality of relay signals to recover a respective portion of a groupcast signal originating from a second UE.

By way of example, and not limitation, such computer-readable media can include a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

Some wireless communication may be exchanged directly between wireless devices based on sidelink. The communication may be based on vehicle-to-anything (V2X) or other device-to-device (D2D) communication, such as Proximity Services (ProSe), etc. Sidelink communication may be exchanged based on a PC5 interface, for example.

In sidelink communication, control information may be indicated by a transmitting UE in multiple SCI parts. The SCI may indicate resources that the UE intends to use, for example, for a sidelink transmission. The UE may transmit a first part of control information indicating information about resource reservation in a physical sidelink control channel (PSCCH) region, and may transmit a second part of the control information in a PSSCH region. For example, a first stage control (e.g., SCI-<NUM>) may be transmitted on a PSCCH and may contain information for resource allocation and information related to the decoding of a second stage control (e.g., SCI-<NUM>). The second stage control (SCI-<NUM>) may be transmitted on a PSSCH and may contain information for decoding data (SCH). Therefore, control information may be indicated through a combination of the first SCI part included in the PSCCH region (e.g., the SCI-<NUM>) and the second SCI part included in the PSSCH region (e.g., the SCI-<NUM>). In other aspects, control information may be indicated in a media access control (MAC) control element (MAC-CE) portion of the PSSCH.

Some examples of sidelink communication may include vehicle-based communication such as vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from the vehicle-based communication device to road infrastructure nodes such as a Road Side Unit (RSU)), vehicle-to-network (V2N) (e.g., from the vehicle-based communication device to one or more network nodes, such as a base station), vehicle-to-pedestrian (V2P), cellular vehicle-to-everything (C-V2X), and/or a combination thereof and/or with other devices, which can be collectively referred to as V2X communications. As an example, in <FIG>, a UE <NUM>, e.g., a transmitting Vehicle User Equipment (VUE) or other UE <NUM>, may be configured to transmit messages directly to another UE <NUM>. The communication may be based on V2X or other D2D communication, such as Proximity Services (ProSe), etc. Communication based on V2X and/or D2D may also be transmitted and received by other transmitting and receiving devices, such as Road Side Unit (RSU) <NUM>, etc. Aspects of the communication may be based on PC5 or sidelink communication e.g., as described in connection with the example in <FIG>. Although the following description may provide examples for V2X/D2D communication in connection with <NUM> NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations <NUM>, UEs <NUM>, an Evolved Packet Core (EPC) <NUM>, and a Core Network (e.g., 5GC) <NUM>.

The base stations <NUM> configured for <NUM> LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC <NUM> through backhaul links <NUM> (e.g., S1 interface). The base stations <NUM> configured for NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with Core Network <NUM> through backhaul links <NUM>. The base stations <NUM> may communicate directly or indirectly (e.g., through the EPC <NUM> or Core Network <NUM>) with each other over backhaul links <NUM> (e.g., X2 interface).

A network that includes both small cell and macro cells may be known as a heterogeneous network. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

A base station <NUM>, whether a small cell <NUM>' or a large cell (e.g., macro base station), may include an eNB, gNodeB (gNB), or other type of base station.

Devices may use beamforming to transmit and receive communication. For example, <FIG> illustrates that a base station <NUM> may transmit a beamformed signal to the UE <NUM> in one or more transmit directions <NUM>'. Although beamformed signals are illustrated between UE <NUM> and base station <NUM>/<NUM>, aspects of beamforming may similarly may be applied by UE <NUM> or RSU <NUM> to communicate with another UE <NUM> or RSU <NUM>, such as based on V2X, V2V, or D2D communication.

The Core Network <NUM> may include a Access and Mobility Management Function (AMF) <NUM>, other AMFs <NUM>, a Session Management Function (SMF) <NUM>, and a User Plane Function (UPF) <NUM>. The AMF <NUM> is the control node that processes the signaling between the UEs <NUM> and the Core Network <NUM>.

The base station <NUM> provides an access point to the EPC <NUM> or Core Network <NUM> for a UE <NUM>.

Further, although the present disclosure may focus on vehicle-to-pedestrian (V2P) communication and pedestrian-to-vehicle (P2V) communication, the concepts and various aspects described herein may be applicable to other similar areas, such as D2D communication, IoT communication, vehicle-to-everything (V2X) communication, or other standards/protocols for communication in wireless/access networks.

<FIG> illustrates example diagram <NUM> illustrating non-limiting examples of time and frequency resources that may be used for wireless communication based on sidelink. In some examples, the time and frequency resources may be based on a slot structure. In other examples, a different structure may be used. The slot structure may be within a <NUM>/NR frame structure in some examples. This is merely one example, and other wireless communication technologies may have a different frame structure and/or different channels. Diagram <NUM> illustrates a single slot transmission, e.g., which may correspond to a <NUM> transmission time interval (TTI).

Each time slot may include a resource block (RB) (also referred to as physical RBs (PRBs)) that extends <NUM> consecutive subcarriers. Diagram <NUM> also illustrates multiple subchannels, where each subchannel may include multiple RBs. For example, one subchannel in sidelink communication may include <NUM>-<NUM> RBs. As illustrated in <FIG>, the first symbol of a subframe may be a symbol for automatic gain control (AGC). Some of the REs may include control information, e.g., along with PSCCH and/or PSSCH. The control information may include Sidelink Control Information (SCI). For example, the PSCCH can include a first-stage SCI. A PSCCH resource may start at a first symbol of a slot, and may occupy <NUM>, <NUM> or <NUM> symbols. The PSCCH may occupy up to one subchannel with the lowest subcarrier index. <FIG> also illustrates symbol(s) that may include PSSCH. The symbols in <FIG> that are indicated for PSCCH or PSSCH indicate that the symbols include PSCCH or PSSCH REs. Such symbols corresponding to PSSCH may also include REs that include a second-stage SCI and/or data. At least one symbol may be used for feedback (e.g., PSFCH), as described herein. As illustrated in <FIG>, symbols <NUM> and <NUM> are indicated for PSFCH, which indicates that these symbols include PSFCH REs. In some aspects, symbol <NUM> of the PSFCH may be a duplication of symbol <NUM>. A gap symbol prior to and/or after the feedback may be used for turnaround between reception of data and transmission of the feedback. As illustrated in <FIG>, symbol <NUM> includes a gap symbol to enable turnaround for feedback in symbol <NUM>. Another symbol, e.g., at the end of the slot (symbol <NUM>) may be used as a gap. The gap enables a device to switch from operating as a transmitting device to prepare to operate as a receiving device, e.g., in the following slot. Data may be transmitted in the remaining REs, as illustrated. The data may include the data message described herein. The position of any of the PSCCH, PSSCH, PSFCH, and gap symbols may be different than the example illustrated in <FIG>.

<FIG> is a block diagram of a first wireless communication device <NUM> in communication with a second wireless communication device <NUM>. The communication may be based on sidelink, e.g., using a PC5 interface. In some examples, the devices <NUM> and <NUM> may communicate based on V2X or other D2D communication. The devices <NUM> and the <NUM> may include a UE, an RSU, a base station, etc. In some examples, the device <NUM> may be a UE and the device <NUM> may be a UE. Packets may be provided to a controller/processor <NUM> that implements layer <NUM> and layer <NUM> functionality.

At least one of the TX processor <NUM>, the RX processor <NUM>, or the controller/processor <NUM> of device <NUM> or the TX <NUM>, the RX processor <NUM>, or the controller/processor <NUM> may be configured to perform aspects described in connection with the cooperative relay configuration component <NUM> and/or the relaying component <NUM> of <FIG>.

<FIG> illustrates an example <NUM> of sidelink communication between wireless devices. The communication may be based on a slot structure comprising aspects described in connection with <FIG> or another sidelink structure. Although the example in <FIG> is described for the UEs <NUM>, <NUM>, <NUM>, <NUM>, aspects may be applied to other wireless devices configured for communication based on sidelink, such as an RSU, an IAB node, etc. As illustrated in <FIG>, a transmitting UE <NUM> may transmit a transmission <NUM> comprising a control information (e.g., sidelink control information (SCI)) and/or a corresponding data channel, that may be received by receiving UEs <NUM>, <NUM>, <NUM>. The SCI may include information for decoding the corresponding data and may also be used by receiving device to avoid interference by refraining from transmitting on the occupied resources during a data transmission. For example, the SCI may reserve resources for sidelink communication. The number of TTIs, as well as the RBs that will be occupied by the data transmission, may be indicated in SCI from the transmitting device. The UEs <NUM>, <NUM>, <NUM>, <NUM> may each be capable of operating as a transmitting device in addition to operating as a receiving device. Thus, the UEs <NUM>, <NUM> are illustrated as transmitting transmissions <NUM> and <NUM>. The transmissions <NUM>, <NUM> or <NUM> may be broadcast or multicast to nearby devices. For example, the UE <NUM> may transmit communication intended for receipt by other UEs within a range <NUM> of the UE <NUM>. In other examples, the transmissions <NUM>, <NUM>, or <NUM> may be groupcast to nearby devices that a member of a group. In other examples, the transmissions <NUM>, <NUM>, or <NUM> may be unicast from one UE to another UE. Additionally or alternatively, the RSU <NUM> may receive communication from and/or transmit communication <NUM> to the UEs <NUM>, <NUM>, <NUM>, <NUM>.

The UE <NUM>, <NUM>, <NUM>, <NUM> and/or the RSU <NUM> may include a cooperative relay configuration component, similar to the cooperative relay configuration component <NUM> described in connection with <FIG>. The UE <NUM>, <NUM>, <NUM>, <NUM> and/or the RSU <NUM> may additionally or alternatively include a relaying component, similar to the relaying component <NUM> described in connection with <FIG>.

Resource allocation refers to how a resource is allocated to a device to use for transmitting a packet. In sidelink communication, resource allocation may be performed in a centralized manner (Mode <NUM>) or a distributed manner (Mode <NUM>). When operating using Mode <NUM>, resource allocations for sidelink communication are determined by a base station. For example, the base station may transmit an indication to a UE that indicates the resources that are allocated to the UE to use to transmit sidelink communication (e.g., sidelink data packets to other UEs). When operating using Mode <NUM>, the resource allocations for sidelink communication are determined by the communicating UE. For example, a transmitting UE may autonomously determine resource allocations for transmitting sidelink control and data to one or more receiving UEs. When operating using Mode <NUM> (e.g., in a distributed manner), the transmitting UE may determine the resources to use for communicating from a resource pool. A resource pool refers to a collection of time and/or frequency resources on which sidelink communication may occur.

As shown in <FIG>, a transmitter (Tx) UE <NUM> and a receiver (Rx) UE <NUM> may communicate with one another via a sidelink. In some sidelink modes, a base station <NUM>/<NUM> may communicate with the Tx UE <NUM> via a first access link (not shown). Additionally, or alternatively, in some sidelink modes, the base station <NUM>/<NUM> may communicate with the Rx UE <NUM> via a second access link (not shown). The Tx UE <NUM> and/or the Rx UE <NUM> may correspond to one or more UEs described elsewhere herein, such as the UE <NUM> of <FIG>. Thus, a direct link between UEs <NUM> (e.g., via a PC5 interface) may be referred to as a sidelink, and a direct link between a base station <NUM>/<NUM> and a UE <NUM> (e.g., via a Uu interface) may be referred to as an access link. Sidelink communications may be transmitted via the sidelink, and access link communications may be transmitted via the access link. An access link communication may be either a downlink communication (from a base station <NUM>/<NUM> to a UE <NUM>) or an uplink communication (from a UE <NUM> to a base station <NUM>/<NUM>).

As described above, the UE <NUM> may operate in Mode <NUM>, in which resource selection and/or scheduling is performed by the base station <NUM>/<NUM>. That is, in Mode <NUM>, the base station <NUM>/<NUM> assigns resources for transmitting sidelink communications. In particular, the base station <NUM>/<NUM> may transmit downlink control information (DCI) (e.g., in DCI format 3_0) that indicates a resource allocation (e.g., time and/or frequency resources) and/or a transmission timing. In Mode <NUM>, a MCS value for sidelink transmissions may be selected by a UE <NUM> (e.g., within limits set by the base station <NUM>/<NUM>). Moreover, Mode <NUM> may support dynamic grants or configured grants for scheduling sidelink transmissions. The configured grants may be type <NUM> (e.g., which may be activated by the base station <NUM>/<NUM> via radio resource control (RRC) signaling) or type <NUM>.

As described above, the UE <NUM> may operate in Mode <NUM>, in which resource selection and/or scheduling is performed by the UE <NUM>. That is, the transmitting UE <NUM> may autonomously determine resources for sidelink transmissions. In this case, the transmitting UE <NUM> may perform channel sensing by performing blind decoding of all PSCCH channels in order to determine resources that are reserved for sidelink transmissions (e.g., by other transmitting UEs). In this way, the transmitting UE <NUM> may determine available resources, which may be reported to an upper layer of the transmitting UE <NUM> where resource usage is determined. The receiving UE <NUM> operates according to the same behavior in Mode <NUM> or Mode <NUM>. In some aspects, the UE <NUM> may perform resource selection and/or scheduling by sensing channel availability for transmissions. For example, the UE <NUM> may measure a received signal strength indicator (RSSI) parameter (e.g., a sidelink-RSSI (S-RSSI) parameter) associated with various sidelink channels, may measure a reference signal received power (RSRP) parameter (e.g., a PSSCH-RSRP parameter) associated with various sidelink channels, may measure a reference signal received quality (RSRQ) parameter (e.g., a PSSCH-RSRQ parameter) associated with various sidelink channels, and/or the like, and may select a channel for transmission of a sidelink communication based at least in part on the measurement(s).

The radio resource allocation for a sidelink communication may be based on resource reservations. For instance, when a UE is preparing to transmit data on sidelink, the UE may first determine whether resources are reserved by other UEs. Then, the UE may reserve resources from the remaining unreserved resources that are available. <FIG> is a diagram <NUM> illustrating an example of resource reservations for sidelink transmissions. The resource allocation for each UE may be in units of one or more subchannels in the frequency domain (e.g., subchannels SC <NUM> to SC <NUM>), and may be based on one time slot in the time domain. The UE may also use resources in the current slot to perform a first transmission, and may reserve resources in future slots for retransmissions. In this example, up to two different future slots may be reserved by the UEs (e.g., UE1 and UE2) for retransmissions. The resource reservation may be limited to a window of pre-defined slots and subchannels, such as an example eight time slots by four subchannels window, as shown in diagram <NUM>, which provides <NUM> available resource blocks in total. This example window may also be referred to as a "resource selection window. " Each resource block in the resource selection window may be used to transmit both data and control information together.

<FIG> also illustrates an example of time frequency resources that may be available for sidelink communication. A resource pool may be either preconfigured (e.g., preloaded on a UE), configured by a base station, or otherwise determined by the UE. In some examples, a transmitting UE may randomly select resources from a resource pool for a transmission. In such examples, receiving UEs may continuously monitor candidate resources to receive a communication. Additionally, in some examples, if a nearby UE randomly selects the same resource, a collision or interference may occur.

In some examples, a UE may use historical resource utilization of other UEs to predict future activity. For example, by identifying that a first UE transmits periodically and what resources the first UE uses when transmitting, a second UE may determine on which resources future transmissions by the first UE may occur and also when they may occur. <FIG> also illustrates an example of period resource <NUM> that may be reserved by a UE for sidelink communication. Thus, by "listening" to other UE activity in the past (e.g., historical resource utilization), the second UE may predict future activity of the other UEs and can select a resource to use for a transmission that is less likely to result in a collision and/or interference.

However, it may be appreciated that for the second UE to identify historical resource utilization, the second UE may operate in an "always-on" mode to facilitate sensing or receiving of transmission by the other UEs. The continual monitoring by the second UE increases power consumption or processing resources in order to identify historical resource utilization and to predict future activity.

In some examples, a UE may perform partial sensing for determining historical resource utilization of other UEs. When performing partial sensing, the UE may selectively sense a subset of resources and, thus, may reduce power consumption in comparison to monitoring the set of resources. However, partial sensing may not be effective when transmissions by other UEs are not periodic. For example, a UE employing partial sensing may miss information about aperiodic transmissions and, thus, may be unable to accurately predict future activity of the other UEs based on a determined historical resource utilization.

In one example, a first UE ("UE1") may reserve a subchannel (e.g., SC <NUM>) in a current slot (e.g., time slot <NUM>) for an initial data transmission (e.g., resource <NUM>), and may reserve additional future slots within the resource selection window for data retransmissions (e.g., resources <NUM>, <NUM>). For example, UE1 may reserve a subchannel SC <NUM> at time slot <NUM> (e.g., the resource <NUM>) for a first future retransmission and may reserve a subchannel SC <NUM> at time slot <NUM> (e.g., the resource <NUM>) for a second future retransmission, as shown by <FIG>. UE1 may then transmit information regarding which resources are being used and/or reserved by UE1 to other UE(s), such as by including reservation information in a reservation resource field of the SCI (e.g., a first stage SCI). In some examples, the UE may be configured to use the SCI to reserve one, two, or three transmissions. In some examples, a maximum number of reservations allowed for a UE may be pre-configured for the UE. For example, a UE may be pre-configured to reserve up to three transmissions within a resource selection window.

As illustrated by <FIG>, a second UE ("UE2") may also reserve resources in subchannels SC <NUM> and SC <NUM> at time slot <NUM> (e.g., resource <NUM>) for a current data transmission. UE2 may also reserve subchannels SC <NUM> and SC <NUM> at time slot <NUM> (e.g., resource <NUM>) to use for transmitting a first data retransmission, and may reserve subchannels SC <NUM> and SC <NUM> at time slot <NUM> (e.g., resource <NUM>) to use for transmitting a second data retransmission, as shown by <FIG>. Similar to the example of UE1, UE2 may then transmit information regarding the resource usage and/or reservation information to other UE(s), such as by using the reservation resource field in SCI. In some examples, a UE may be configured to make reservations using a same number of subchannels (e.g., bandwidth). For example, the resources <NUM>, <NUM>, <NUM> reserved by UE1 have a same number of subchannels (e.g., <NUM>), and the resources <NUM>, <NUM>, <NUM> reserved by UE2 have a same number of subchannels (e.g., <NUM>). However, the starting subchannel for each reserved resource may be different. For example, the initial data transmission may start at subchannel SC <NUM>, the first future retransmission may start at subchannel SC <NUM>, and the second future retransmission may start at subchannel SC3, etc..

<FIG> is a diagram <NUM> illustrating an example of a resource reservation process. When a UE (e.g., sidelink transmitting UE) is using a first resource <NUM> for transmission at time slot i in a period (such as period <NUM> illustrated in <FIG>), the UE may reserve two more resources within the same period, such as a first future resource <NUM> at time slot i + x and a second future resource <NUM> at time slot i + y. Each of the reserved resources <NUM>, <NUM>, <NUM> may be associated with a number z of subchannels. For example, if the period has <NUM> slots with slot index <NUM> to <NUM>, the UE may transmit using the first resource <NUM> at time slot <NUM> with z subchannels, and may reserve the first future resource <NUM> with z subchannels at time slot i + x, where x is <NUM> < x ≤ <NUM>. The UE may also reserve the second future resource <NUM> with z subchannels at time slot i +y, where y is x < y ≤ <NUM>. Table <NUM> (below) illustrates example reservations signaled by the SCI of the UE in time slot i corresponding to <FIG>.

The UE may use the first reserved future resource <NUM> and the second reserved future resource <NUM> for retransmission, such as when a first transmission using the first resource <NUM> fails. The UE may additionally or alternatively use one or both of the reserved future resources <NUM>, <NUM> for purposes other than retransmission.

A UE using a reserved resource for transmission may request feedback with respect to the transmission from other UE(s) or base station(s). Based on the feedback from other UE(s) or base station(s), the UE may elect not to use a reserved resource. For example, a transmitting UE may use the first resource <NUM> for a data transmission, and may request a receiving UE or a base station receiving the data transmission to provide feedback to the transmitting UE. If the transmitting UE receives feedback from the receiving UE or the base station confirming receipt of the data transmission, the transmitting UE may elect not to use the reserved future resources <NUM>, <NUM>, which may have been originally reserved for retransmissions of the data transmission.

The sidelink resource reservation may be periodic or aperiodic. For example, a UE may periodically reserve resources, such as by indicating a reservation period in an SCI or in one part of the SCI (e.g., a first state control (SCI-<NUM>)). Thus, when the periodic resource reservation is enabled, the reservations indicated by the SCI may be repeated with the signaled period. In some examples, if the resource reservation is periodic, the reservation period may be configured to values between <NUM> milliseconds (ms) and <NUM> by signaling in the SCI, and the periodic resource reservation may additionally or alternatively be disabled by a (pre-)configuration. In some examples, each reservation of resources may have a priority level indicated in the SCI. In some such example, a higher priority reservation may pre-empt a lower priority reservation.

In sidelink communication, a resource reservation may be indicated by a transmitting UE in multiple SCI parts. The SCI may indicate resources that the UE intends to use, for example, for a sidelink transmission. The UE may transmit a first part of the reservation in a physical sidelink control channel (PSCCH) region, and may transmit a second part of the reservation in a PSSCH region. For example, a first stage control (e.g., SCI-<NUM>) may be transmitted on a PSCCH and may contain information for resource allocation and information related to the decoding of a second stage control (e.g., SCI-<NUM>). The second stage control (SCI-<NUM>) may be transmitted on a PSSCH and may contain information for decoding data (SCH). Therefore, multiple resources may be indicated (or reserved) through a combination of the first SCI part included in the PSCCH region (e.g., the SCI-<NUM>) and the second SCI part included in the PSSCH region (e.g., the SCI-<NUM>). For example, the first SCI part in the PSCCH may reserve resource(s) for a UE in a PSSCH, and the first SCI part may also indicate to a receiving UE that there is a second SCI part or more (e.g., two-stage control SCI) in the PSSCH. The second SCI part may reserve other resources, provide signaling, and/or provide information to the receiving UE that may be unrelated to the resources reserved in the first SCI part.

<FIG> is a diagram <NUM> illustrating an example of a two-stage SCI. To reduce control overhead and to improve the processing timeline, SCI used for sidelink grant(s) may be split into two or more parts. In the illustrated example, a first SCI part <NUM> (e.g., SCI-<NUM>) may be transmitted within a control region (e.g., a PSCCH region <NUM>) and a second SCI part <NUM> (e.g., SCI-<NUM>) may be transmitted within a sidelink traffic region (e.g., a PSSCH region <NUM>). The PSCCH region <NUM> and the PSSCH region <NUM> may together form one slot. The first SCI part <NUM> may include initial control information regarding a sidelink transmission, such as a resource assignment (RA) in SCH <NUM> or other resource reservation information in future slots, rank and modulation order of the sidelink assignment, a bandwidth for the PSSCH region <NUM>, and/or the like. The first SCI part <NUM> is intended for all UEs to decode, particularly for Mode <NUM> UEs to avoid resource collisions. In addition, the first SCI part <NUM> may include control information about the second SCI part <NUM>. In some examples, the control information may indicate the number of resource elements (or size) and code rate of the second SCI part <NUM>. The control information may further indicate the location (e.g., starting resource element) and code rate of the second SCI part <NUM>. In one aspect, the first SCI part <NUM> (e.g., SCI-<NUM>) format may include one or more of the following information: a priority (QoS value), frequency domain resource allocation (FDRA), time domain resource allocation (TDRA), a PSSCH resource assignment (e.g., frequency/time resource for PSSCH), a resource reservation period (e.g., if enabled), a PSSCH DMRS pattern (e.g., if more than one pattern is configured), a second SCI format (e.g. information on the size of the second SCI part), a <NUM>-bit beta offset for second stage control resource allocation, a number of PSSCH DMRS port(s) (e.g., <NUM> or <NUM>), a <NUM>-bit MCS and/or reserved bits. In one aspect, the second SCI part <NUM> (e.g., SCI-<NUM>) format may include one or more of the following information: hybrid automatic repeat request (HARQ), redundancy version (RV) identifiers, new data indicator (NDI), etc. The second SCI part <NUM> may include the remaining control information regarding the sidelink assignment. For example, the remaining control information may include non-time critical control information or other resource allocation(s) for data transmission in SCH <NUM>, such as the source and destination ID for the data transmission.

In some implementations, sidelink communications may use a resource pool that includes one or more subchannels (e.g., subchannels SC <NUM> to SC <NUM>). Accordingly, to receive a sidelink packet, a receiving UE performs blind decoding in all subchannels of the resource pool. A quantity of subchannels in a resource pool may be relatively small (e.g., <NUM>-<NUM> subchannels, as described above), so that blind decoding all subchannels is feasible for a UE. In C-V2X, for example, the UEs are intended to decode all transmissions using blind decoding of all subchannels. In some examples, the subchannel size in V2X is relatively large (e.g., minimum <NUM> RBs).

In some implementations, a PSCCH in the PSCCH region <NUM> and a PSSCH in the PSSCH region <NUM> may be transmitted in the same slot. The PSSCH region <NUM> may occupy contiguous subchannels up to the total quantity of subchannels in the resource pool (e.g., the PSSCH may occupy <MAT>). The PSCCH region <NUM> may occupy only one subchannel (e.g., a subchannel of the resource pool associated with the lowest subchannel index, such as SC1 of <FIG>).

A UE may locate the PSSCH carrying the second SCI part <NUM> after decoding first SCI part <NUM> in the PSCCH region <NUM>. The packet for the second SCI part <NUM> may indicate a source identifier and a destination identifier to indicate a UE that transmitted the packet and a UE for which the packet is intended.

<FIG> is a diagram illustrating an example of cooperative relay in sidelink networks, in accordance with one or more of aspects of the present disclosure. The cooperative sidelink relaying may be performed via a two-step approach, where (<NUM>) a source UE transmits a groupcast signal to other sidelink UEs that serve as relaying stations, and (<NUM>) the sidelink UEs perform synchronized or asynchronized cooperative MIMO to relay the groupcast signal to a remote apparatus (e.g., other sidelink UE or base station).

As shown in <FIG>, the source UE <NUM> broadcasts a groupcast signal on a sidelink broadcast link <NUM>. The relay UEs <NUM>, <NUM> and <NUM> respectively receive this transmission of sidelink data from the source UE <NUM>, and cooperatively relay this transmission to the remote apparatus <NUM> on respective relay links <NUM>, <NUM>, <NUM>. In certain aspects, the data transmission of source UE <NUM> is transmitted to the remote apparatus <NUM> over multiple hops. For example, the relay UEs <NUM>, <NUM>, <NUM> may forward the data transmission to the remote apparatus <NUM> as unicast transmissions.

A source UE <NUM> may generally be able to transmit uplink data through a single relay station to a base station. However, uplink coverage through the single relay station between the source UE and the base station in a multi-hop scenario may be limited due to power constraints, UL interference from other stronger UEs in the vicinity, etc. In certain aspects of the present disclosure, the source UE <NUM> may participate, with one or more other sidelink UEs (e.g., UEs <NUM>, <NUM>, <NUM>) in the network <NUM>, in cooperative relay transmission to a base station (e.g., base station <NUM>/<NUM>). If the destination is a base station (e.g., gNB), then the subject technology can be used as a technique to improve uplink coverage, albeit at the cost of latency (e.g., over two-hop transmissions). In certain aspects, the source UE <NUM> may communicate UL data to the base station (e.g., <NUM>) using intermediary relay stations (e.g., UEs <NUM>, <NUM>, <NUM>) to cooperatively relay the data transmitted by the source UE <NUM>.

A first relay station (e.g., relay UEs <NUM>, <NUM>, <NUM>) may receive control information that configures the first relay station and at least one other sidelink UE (e.g., UEs <NUM>, <NUM>, <NUM>) as relay stations between the source UE <NUM> and a remote apparatus (e.g., <NUM>). In some aspects, the remote apparatus <NUM> may be a sidelink UE. In other aspects, the remote apparatus <NUM> may be a base station.

The first relay station receives from the source UE <NUM>, a groupcast signal that includes a resource allocation assigned to a plurality of sidelink UEs including the first relay station. The resource allocation includes time and frequency resource allocation for the relay stations to transmit at least a portion of the groupcast signal to the remote apparatus <NUM>. In particular, the resource allocation may indicate in which slot(s) the relay stations should transmit the at least the portion of the groupcast signal to the remote apparatus <NUM>. The resource allocation also may indicate in what time (or symbol duration) and frequency resource (e.g., resource block), for a given slot, the relay stations should transmit the at least the portion of the groupcast signal to the remote apparatus <NUM>. In some implementations, the resource allocation includes a first set of resources indicating first time and frequency resources for a first hop transmission path between the source UE <NUM> and the first relay station and a second set of resources indicating second time and frequency resources for a second hop transmission path between the first relay station and the remote apparatus <NUM>. In some aspects, the first resource includes a plurality of physical sidelink shared channels (PSSCHs), multiplexed in time or frequency. In some aspects of receiving the groupcast signal, the first relay station can receive the groupcast signal in a first PSSCH of the plurality of PSSCHs. In some aspects, the first PSSCH includes a second stage sidelink control information (SCI-<NUM>). In this regard, the first relay station may receive the resource allocation in a common portion of the SCI-<NUM> when the synchronous relay mode is selected. Alternatively, the relay station may receive the resource allocation in a UE-specific portion of the SCI-<NUM>. In other aspects, the first relay station may receive the resource allocation in the MAC-CE of the first PSSCH.

In some implementations, the at least a portion of the groupcast signal includes a second stage sidelink control information (SCI-<NUM>). In some aspects of receiving the groupcast signal, the wireless communication device may receive a common virtual relay identifier in the SCI-<NUM>. In some aspects, the common virtual relay identifier is equivalent between the first relay station and the at least one other sidelink UE.

The first relay station may determine whether the first relay station operates in a synchronous relay mode or an asynchronous relay mode with the at least one other sidelink UE based on at least a portion of the groupcast signal. The relay station may determine that the first relay station operates in the synchronous relay mode with the at least one other sidelink UE based on the common virtual relay identifier being received in the SCI-<NUM>. The relay station may forward the common virtual relay identifier in the first relay signal that is equivalent to a relay identifier included in the second relay signal based on the synchronous relay mode between the first relay station and the at least one other sidelink UE.

In some implementations, the source UE <NUM> may select between a synchronous relay mode or an asynchronous relay mode based on a sidelink synchronization procedure with the plurality of second UEs when the source <NUM> and the relay stations operate in the sidelink Mode <NUM> of operation, as described in reference to <FIG>. For example, if the synchronization among all sidelink UEs is successful, then the source UE <NUM> can set up the cooperative relay mechanism as a synchronized relay. If all of the relay UEs do not synchronize successfully, then the source UE <NUM> can set up the cooperative relay as an asynchronous relay. In some implementations, if not all relay UEs synchronize successfully (i.e., some relay UEs may synchronize successfully), then the source UE <NUM> can set up a hybrid synchronization relay mode, where some of the relay UEs operate in the synchronized relay mode and another portion of the relay UEs operate in the asynchronized relay mode. The source UE <NUM> may send separate resource allocation for each relay mode, which may add cost and/or complexity to overhead sidelink signaling (e.g., SCI).

The first relay station may transmit a unique relay identifier in the first relay signal that is different from a relay identifier included in the second relay signal based on an asynchronous relay mode between the first relay station and the at least one other sidelink UE. In some aspects, the first relay station may determine the unique relay identifier independent of the base station and/or the other sidelink UEs.

The first relay station may transmit an indication of the second set of resources to the remote apparatus so that the remote apparatus combines the first relay signal with the second relay signal to recover data from the source UE. In this regard, the indication may indicate whether the relay signals from the multiple relay stations may be received in a same time and frequency resource or at different time and frequency resources depending on the relay mode of operation (e.g., synchronous or asynchronous) among the relay stations. For example, a first resource used by the first relay station may include a same time and frequency resource as a second resource used by the other relay station in the synchronous relay mode. In other examples, the first resource includes a different time and frequency resource than the second resource in the asynchronous relay mode.

The first relay station may communicate, with the remote apparatus <NUM> on a first resource included in the resource allocation, a first relay signal that includes at least a portion of the groupcast signal. In some aspects, the first relay signal corresponds to at least a portion of a second relay signal communicated with the remote apparatus on a second resource included in the resource allocation by at least one other sidelink UE (e.g., UEs <NUM>, <NUM>, <NUM>). The first relay station may transmit the first relay signal concurrently with the at least a portion of the second relay signal to the remote apparatus <NUM> through a relay link (e.g., relay links <NUM>, <NUM>). In one or more implementations, the first relay station can transmit the first relay signal as a unicast transmission to the remote apparatus <NUM>.

In some implementations, the remote apparatus <NUM> may obtain log-likelihood ratio (LLR) values of each received relay signal and perform summation of the LLR values to reconstruct the original signal that originates from the source UE <NUM>. In some aspects, when the relay stations operate in the synchronous relay mode, the remote apparatus <NUM> may treat each of the relay signals as a virtual single relay and receive the relay signal as a single instance. In this regard, the received relay signal at the remote apparatus <NUM> may be processed as: Y = h<NUM>*s + h<NUM>*s +. + hN*s + noise = (h<NUM> + h<NUM> +. + hN) *s + noise = hBAR*s + noise. In other aspects, when the relay stations operate in the asynchronous relay mode, the remote apparatus <NUM> may receive the relay signals on different resources. In this regard, the received relay signals at the remote apparatus <NUM> may be processed as: Y<NUM> = h<NUM>*s + noise<NUM>; Y<NUM> = h<NUM>*s + noise<NUM>;. ; YN = hN*s + noiseN. The remote apparatus <NUM> may receive the multiple relay signals at multiple times (or at different times), one from each relay station as a data source.

<FIG> is an example communication flow <NUM> for cooperative relay in sidelink networks, in accordance with one or more of the teachings disclosed herein. According to the call flow <NUM>, a sidelink communication between UE pairs is provided, a first of which may include a UE 904a and a UE 904b and a second of which may include the UE 904a and a UE 904c. In the context of <FIG>, each of the UEs 904a, 904b, 904c may be implemented as one of the UEs <NUM> in some implementations, or each of the UEs 904a, 904b may be implemented as one of the UEs <NUM> and the device 904c may be implemented as the BS <NUM>/<NUM> in other implementations. In the context of <FIG>, each of the UEs 904a, 904b, 904c may be implemented as the UE <NUM> in some implementations, or each of the UEs 904a, 904b may be implemented as the UE <NUM> and the device 904c may be implemented as the base station <NUM> in other implementations.

For sidelink communication, the UEs 904a, 904b, 904c may directly communicate with one another over a sidelink. Examples of such a sidelink may include the PC5 interfaces defined for V2X in LTE and/or <NUM> NR. Communication on the sidelink may be carried on at least one channel.

On the sidelink, control information may be carried on a sidelink control channel 910a, such as the PSCCH. Data on the sidelink, however, may be carried on a sidelink data channel 910b, which may also be referred to as a sidelink shared channel. An example of the sidelink data channel 910b may include the PSSCH.

To directly receive data on the sidelink data channel 910b, the data may be scheduled on a set of resources on the sidelink data channel 910b. Scheduling information for the data on the sidelink data channel 910b may be carried on the sidelink control channel 910a. Thus, in order to directly communicate data on the sidelink data channel 910b, each of the UEs 904a, 904b, 904c may first receive and decode the sidelink control channel 910a.

For the sidelink communication on the allocated set of resources <NUM>, each of the UEs 904a, 904b, 904c may identify another one of the UEs 904a, 904b, 904c, e.g., in order to establish a UE pair for sidelink communication. The UEs 904a, 904b, 904c may identify another one of the UEs 904a, 904b, 904c with which to engage in sidelink communication based on the discovery phase. The discovery phase may occur on a sidelink discovery channel (e.g., PSDCH), on which one of the UEs 904a, 904b, 904c may announce a service provided by that one of the UEs 904a, 904b, 904c while another one of the UEs 904a, 904b, 904c may determine that the announced service is of interest to that other one of the UEs 904a, 904b, 904c.

At <NUM>, In some implementations, the UE 904b may select between a synchronous relay mode or an asynchronous relay mode based on a sidelink synchronization procedure with the plurality of second UEs when the UE 904b and the relay stations operate in the sidelink Mode <NUM> of operation, as described in reference to <FIG>. For example, if the synchronization among all sidelink UEs is successful, then the UE 904b can set up the cooperative relay mechanism as a synchronized relay. If all of the relay UEs do not synchronize successfully, then the UE 904b can set up the cooperative relay as an asynchronous relay. In some implementations, if not all relay UEs synchronize successfully (i.e., some relay UEs may synchronize successfully), then the UE 904b can set up a hybrid synchronization relay mode, where some of the relay UEs operate in the synchronized relay mode and another portion of the relay UEs operate in the asynchronized relay mode. The UE 904b may send separate resource allocation for each relay mode, which may add cost and/or complexity to overhead sidelink signaling (e.g., SCI).

At <NUM>, the UE 904b may determine a first set of resources for a first hop transmission path and a second set of resources for a second hop transmission path. In some implementations, the resource allocation includes a first set of resources indicating first time and frequency resources for a first hop transmission path between the UE 904b and the first relay station and a second set of resources indicating second time and frequency resources for a second hop transmission path between the first relay station and the UE 904c.

In the aspects illustrated by <FIG>, the UE 904b may have first sidelink data <NUM> to send to the UE 904a, and the UE 904a may have second sidelink data <NUM> to send to the UE 904c. In order to send data on the sidelink, the UE 904a and the UE 904b may determine respective control information <NUM>, <NUM> associated with the sidelink data channel 910b.

The control information <NUM>, <NUM> may enable the UE 904a and the UE 904c, respectively, to successfully detect and decode the data on the sidelink data channel 910b from the UE 904b and the UE 904a. For example, the control information <NUM>, <NUM> may indicate at least one of a schedule for receiving data on the sidelink data channel 910b, an MCS for communication on the sidelink data channel 910b, information associated with a HARQ process for the sidelink data channel 910b, a set of resources allocated on the sidelink data channel 910b to carry the data, and/or a TCI state associated with the sidelink data channel 910b.

The UE 904b may allocate a set of resources for sidelink communication with the UE 904a. For example, the resource allocation includes time and frequency resource allocation for the relay stations to transmit at least a portion of the groupcast signal to the UE 904c. In particular, the resource allocation may indicate in which slot(s) the relay stations should transmit the at least the portion of the groupcast signal to the remote apparatus <NUM>. The resource allocation also may indicate in what time (or symbol duration) and frequency resource (e.g., resource block), for a given slot, the relay stations should transmit the at least the portion of the groupcast signal to the UE 904c. By allocating the set of resources for sidelink communication, the first UE 904b may reduce or prevent conflicts, interference, and the link on resources in the cell. The set of resources may include a set of PRBs and/or time/frequency resources. Sidelink communication may occur in a mmW spectrum and/or near-mmW spectrum. For example, one or more 3GPP standards for <NUM> NR may define communication in mmW and/or near-mmW frequencies.

During one or more slots configured for transmission by the UE 904b, the UE 904b may send the sidelink control information <NUM> to the UE 904a on the sidelink control channel 910a. The UE 904a may be monitoring a set of resources allocated for the sidelink control channel 910a.

The UE 904b may directly send sidelink data <NUM> on the sidelink data channel 910b to the UE 904a. The UE 904b may send the sidelink data <NUM> on the sidelink data channel 910b based on the sidelink control information <NUM>. For example, the UE 904b may send the sidelink data <NUM> on the sidelink data channel 910b according to a schedule indicated in the sidelink control information <NUM>. The schedule may indicate a first set of resources for a first hop transmission path between the UE 904b and the UE 904a.

At <NUM>, the UE 904a may successfully detect and decode the sidelink control information <NUM>. Based on the sidelink control information <NUM>, the UE 904a may successfully receive and decode the sidelink data <NUM> on the sidelink data channel 910b.

The UE 904a may obtain various parameters from the sidelink control information <NUM> for sidelink communication on the sidelink data channel 910b, such as a schedule for receiving the sidelink data <NUM> (e.g., PSSCH) on the sidelink data channel 910b. At <NUM>, the UE 904a may perform blind-decoding of all subchannels to identify the sidelink control information <NUM> and decode the sidelink control information <NUM>, such as the SCI-<NUM>. At <NUM>, the UE 904a can determine resources associated with sidelink communication within the cooperative relaying mechanism relative to other sidelink transmitting UE(s), as described in reference to the UEs <NUM>, <NUM>, <NUM> of <FIG>.

During the set of slots configured for transmission by the UE 904a according to the sidelink control information <NUM>, the UE 904a may send the sidelink control information <NUM> to the UE 904c on the sidelink control channel 910a. The UE 904c may be monitoring a set of resources allocated for the sidelink control channel 910a. For example, the sidelink control information <NUM> may include a second set of resources indicating second time and frequency resources for a second hop transmission path between the UE 904a and the UE 904c.

Subsequently, the UE 904a may directly send second sidelink data <NUM> on the sidelink data channel 910b to the UE 904c. The UE 904a may send the sidelink data <NUM> on the sidelink data channel 910b based on the sidelink control information <NUM>. For example, the UE 904a may send the sidelink data <NUM> on the sidelink data channel 910b according to a schedule indicated in the sidelink control information <NUM>. In some aspects, the sidelink data <NUM> includes a common virtual relay identifier when the UE 904a operates in a synchronous relay mode. In other aspects, the sidelink data <NUM> includes a unique relay identifier when the UE 904a operates in an asynchronous relay mode.

In a set of slots configured according to the sidelink control information <NUM>, the UE 904c may successfully detect and decode the sidelink control information <NUM> on the sidelink control channel 910a. The UE 904c may obtain various parameters from the sidelink control information <NUM> for sidelink communication on the sidelink data channel 910b, such as a schedule for receiving the second sidelink data <NUM> on the sidelink data channel 910b. In some aspects, the UE 904c may receive the sidelink data <NUM> in the same time and frequency resource as other relay stations when the UE 904a is operating in the synchronous relay mode with other sidelink transmitting UE(s) serving as relay stations. In other aspects, the UE 904c may receive the sidelink data <NUM> on different time and frequency resources from the UE 904a and other relay stations when the UE 904a is operating in the asynchronous relay mode with the other sidelink transmitting UE(s).

<FIG> is a flowchart of a process <NUM> of wireless communication. The process <NUM> may be performed by a wireless communication device (e.g., the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>; the device <NUM>, the RSU <NUM>, <NUM>, UEs <NUM>, <NUM>, <NUM>, UE 904a; the apparatus <NUM>, which may include memory, a cellular baseband processor <NUM>, and one or more components configured to perform the <NUM>). As illustrated, the process <NUM> includes a number of enumerated steps, but embodiments of the process <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. Optional aspects are illustrated with a dashed line. The process <NUM> enables a wireless communication device to facilitate cooperative relaying in sidelink networks by providing sidelink control information to other sidelink transmitting UE(s) serving as relay stations to forward source UE data to a destination through a synchronous relay mode or asynchronous relay mode. The cooperative relaying through sidelink transmitting UE(s) provides diversity gain and power gain with increased reliability and coverage of the relay link between the sidelink transmitting UE(s) and the destination. Thus, the mechanism may increase uplink coverage to a base station serving as the destination or increase sidelink coverage to a sidelink receiving UE serving as the destination.

At <NUM>, the wireless communication device may receive control information that configures a first UE (e.g., UEs <NUM>, <NUM>, <NUM>) and the at least one other sidelink UE (e.g., UEs <NUM>, <NUM>, <NUM>) as relay stations between a second UE (e.g., UE <NUM>) and a remote apparatus (e.g., <NUM>). In some aspects, the remote apparatus may be a UE. In other aspects, the remote apparatus may be a base station. The control information may be received, e.g., by the configuration component <NUM> of the apparatus <NUM> through the reception component <NUM> of the apparatus <NUM> in <FIG>.

In some implementations, the first UE and the at least one other sidelink UE operate in a first mode of sidelink communication, as described in reference to <FIG>. In this regard, the wireless communication device can receive a downlink configuration from a base station at a first time. In some aspects of receiving the groupcast signal, the wireless communication device may receive the groupcast signal from the second UE at a second time subsequent to the first time.

In other implementations, the first UE and the at least one other sidelink UE operate in a second mode of sidelink communication, as described in reference to <FIG>. In this regard, the wireless communication device can receive a sidelink configuration from the second UE at a first time. In some aspects of receiving the groupcast signal, the wireless communication device may receive the groupcast signal from the second UE at a second time subsequent to the first time.

As illustrated at <NUM>, the wireless communication device may receive, from a second UE, a groupcast signal comprising a resource allocation assigned to a plurality of sidelink UEs including the first UE. The groupcast signal may be received, e.g., by the groupcast component <NUM> of the apparatus <NUM> through the reception component <NUM> of the apparatus <NUM> in <FIG>. In some implementations, the resource allocation includes a first set of resources indicating first time and frequency resources for a first hop transmission path between the second UE and the first UE and a second set of resources indicating second time and frequency resources for a second hop transmission path between the first UE and the remote apparatus. In some aspects, the first resource includes a plurality of physical sidelink shared channels (PSSCHs), multiplexed in time or frequency. In some aspects of receiving the groupcast signal, the wireless communication device can receive the groupcast signal in a first PSSCH of the plurality of PSSCHs. In some aspects, the first PSSCH includes a second stage sidelink control information (SCI-<NUM>). In this regard, the wireless communication device may receive the resource allocation in a common portion of the SCI-<NUM> when the synchronous relay mode is selected. Alternatively, the wireless communication device can receive the resource allocation in a UE-specific portion of the SCI-<NUM>. In other aspects, the wireless communication device may receive the resource allocation in the MAC-CE of the first PSSCH.

At <NUM>, the wireless communication device may determine whether the first UE operates in a synchronous relay mode or an asynchronous relay mode with the at least one other sidelink UE based on at least a portion of the groupcast signal. The synchronous relay mode or the asynchronous relay mode may be determined, e.g., by the relay mode component <NUM> of the apparatus <NUM> through coordination with the determination component <NUM> of the apparatus <NUM> in <FIG>. At <NUM>, the wireless communication device performs the determination operation, where if the wireless communication device determines that the wireless communication device operates in the synchronous relay mode, then the process <NUM> proceeds to block <NUM>. Otherwise, the wireless communication device determines that the wireless communication device operates in the asynchronous relay mode and the process <NUM> proceeds to block <NUM>.

At <NUM>, the wireless communication device may transmit a unique relay identifier in the first relay signal that is different from a relay identifier included in the second relay signal based on an asynchronous relay mode between the first UE and the at least one other sidelink UE. The unique relay identifier in the first relay signal may be transmitted, e.g., by the relay identifier component <NUM> of the apparatus <NUM> through the transmission component <NUM> of the apparatus <NUM> in <FIG>.

At <NUM>, the wireless communication device may transmit an indication of the second set of resources to the remote apparatus so that the remote apparatus combines the first relay signal with the second relay signal to recover data from the second UE. The indication may be indicated, e.g., by the resource component <NUM> of the apparatus <NUM> through the transmission component <NUM> of the apparatus <NUM> in <FIG>.

In some implementations, the at least a portion of the groupcast signal includes a second stage sidelink control information (SCI-<NUM>). In some aspects of receiving the groupcast signal, the wireless communication device may receive a common virtual relay identifier in the SCI-<NUM>. In some aspects, the common virtual relay identifier is equivalent between the first UE and the at least one other sidelink UE. At <NUM>, the wireless communication device may determine that the first UE operates in the synchronous relay mode with the at least one other sidelink UE based on the common virtual relay identifier being received in the SCI-<NUM>. The synchronous relay mode may be determined, e.g., by the relay mode component <NUM> of the apparatus <NUM> through coordination with the determination component <NUM> of the apparatus <NUM> in <FIG>.

At <NUM>, the wireless communication device may transmit a common virtual relay identifier in the first relay signal as a source identifier that is equivalent to a relay identifier included in the second relay signal based on the synchronous relay mode between the first UE and the at least one other sidelink UE. The common virtual relay identifier may be transmitted, e.g., by the relay identifier component <NUM> of the apparatus <NUM> through the transmission component <NUM> of the apparatus <NUM> in <FIG>. In some aspects, the source identifier may indicate that the first UE is a data source.

At <NUM>, the wireless communication device may communicate, with a remote apparatus (e.g., UE <NUM>, UE 904c) on a first resource included in the resource allocation, a first relay signal comprising at least a portion of the groupcast signal. In some aspects, the first relay signal corresponds to at least a portion of a second relay signal communicated with the remote apparatus on a second resource included in the resource allocation by at least one other sidelink UE of the plurality of sidelink UEs (e.g., UEs <NUM>, <NUM>, <NUM>). The first relay signal may be communicated, e.g., by the relay mode component <NUM> of the apparatus <NUM> and/or the processor component <NUM> of the apparatus <NUM> through the transmission component <NUM> of the apparatus <NUM> in <FIG>.

In some aspects of communicating the first relay signal, the wireless communication device may transmit the first relay signal concurrently with the at least a portion of the second relay signal to the remote apparatus. In one or more implementations, the wireless communication device can transmit the first relay signal as a unicast transmission to the remote apparatus. In some implementations, the first resource includes a same time and frequency resource as the second resource in the synchronous relay mode. In some implementations, the first resource includes a different time and frequency resource than the second resource in the asynchronous relay mode.

<FIG> is a flowchart of a process <NUM> of wireless communication. The process <NUM> may be performed by a wireless communication device (e.g., the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>; the device <NUM>, the RSU <NUM>, <NUM>, UE <NUM>, UE 904b; the apparatus <NUM>, which may include memory, a cellular baseband processor <NUM>, and one or more components configured to perform the process <NUM>). As illustrated, the process <NUM> includes a number of enumerated steps, but embodiments of the process <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. Optional aspects are illustrated with a dashed line. The process <NUM> enables a wireless communication device to facilitate cooperative relaying in sidelink networks by providing sidelink control information to other sidelink transmitting UE(s) serving as relay stations to forward source UE data to a destination through a synchronous relay mode or asynchronous relay mode. The cooperative relaying through sidelink transmitting UE(s) provides diversity gain and power gain with increased reliability and coverage of the relay link between the sidelink transmitting UE(s) and the destination. Thus, the mechanism may increase uplink coverage to a base station serving as the destination or increase sidelink coverage to a sidelink receiving UE serving as the destination.

At <NUM>, the wireless communication device transmits control information that configures a plurality of second UEs as relay stations between the wireless communication device and a remote apparatus. The control information may be transmitted, e.g., by the configuration component <NUM> of the apparatus <NUM> through the transmission component <NUM> of the apparatus <NUM> in <FIG>.

At <NUM>, the wireless communication device determines a resource allocation assigned to a plurality of second UEs for forwarding data between the first UE and a remote apparatus through a cooperative relay with the plurality of second UEs. The resource allocation may be determined, e.g., by the resource component <NUM> of the apparatus <NUM> through coordination with the determination component <NUM> of the apparatus <NUM> in <FIG>. In some aspects, the resource allocation includes a first set of resources indicating first time and frequency resources for a first hop transmission path between the first UE and the plurality of second UEs and a second set of resources indicating second time and frequency resources for a second hop transmission path between the plurality of second UEs and the remote apparatus.

At <NUM>, the wireless communication device may select between a synchronous relay mode or an asynchronous relay mode based on a sidelink synchronization procedure with the plurality of second UEs. The synchronous relay mode or the asynchronous relay mode may be selected, e.g., by the relay mode component <NUM> through coordination with the determination component <NUM> of the apparatus <NUM> in <FIG>. At <NUM>, the wireless communication device performs the selection operation, where if the wireless communication device selects the synchronous relay mode, then the process <NUM> proceeds to block <NUM>. Otherwise, the wireless communication device selects the asynchronous relay mode and the process <NUM> proceeds to block <NUM>.

At <NUM>, the wireless communication device may provide the resource allocation in a common portion of a sidelink control information portion of the groupcast signal when the synchronous relay mode is selected. The resource allocation in the common portion of the sidelink control information portion may be provided, e.g., by the configuration component <NUM> of the apparatus <NUM> through coordination with the resource component <NUM> of the apparatus <NUM> in <FIG>.

Alternatively, at <NUM>, the wireless communication device can provide the resource allocation in a UE-specific portion of the sidelink control information portion of the groupcast signal when the asynchronous relay mode is selected. The resource allocation in the UE-specific portion of the sidelink control information portion may be provided, e.g., by the configuration component <NUM> of the apparatus <NUM> through coordination with the resource component <NUM> of the apparatus <NUM> in <FIG>.

At <NUM>, the wireless communication device may transmit, to the plurality of second UEs on a first resource over a sidelink channel, a groupcast signal comprising the resource allocation. The groupcast signal may be transmitted, e.g., by the groupcast component <NUM> of the apparatus <NUM> through the transmission component <NUM> of the apparatus <NUM> in <FIG>. In some aspects, the plurality of second UEs operate in a second mode of sidelink communication. In some aspects of transmitting the control information, the wireless communication device can transmit a sidelink configuration to the plurality of second UEs at a first time. In some aspects of transmitting the groupcast signal, the wireless communication device can transmit the groupcast signal to the plurality of second UEs at a second time subsequent to the first time.

In some aspects, the first resource includes a plurality of physical sidelink shared channels (PSSCHs), multiplexed in time or frequency. In some aspects of transmitting the groupcast signal, the wireless communication device can transmit the groupcast signal in a first PSSCH of the plurality of PSSCHs. In some aspects, the first PSSCH includes a second stage sidelink control information (SCI-<NUM>). In this regard, the wireless communication device may provide the resource allocation in a common portion of the SCI-<NUM> when the synchronous relay mode is selected. Alternatively, the wireless communication device can provide the resource allocation in a UE-specific portion of the SCI-<NUM>. In other aspects, the wireless communication device may provide the resource allocation in the MAC-CE of the first PSSCH.

<FIG> is a flowchart of a process <NUM> of wireless communication. The process <NUM> may be performed by a wireless communication device (e.g., the UE <NUM>, <NUM>, <NUM>, <NUM>, <NUM>; the BS <NUM> or <NUM>, the device <NUM> or <NUM>, the RSU <NUM>, <NUM>, the device <NUM>, the device 904c; the apparatus <NUM>, which may include memory, a cellular baseband processor <NUM>, and one or more components configured to perform the process <NUM>). As illustrated, the process <NUM> includes a number of enumerated steps, but embodiments of the process <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. Optional aspects are illustrated with a dashed line. The process <NUM> enables a wireless communication device to facilitate cooperative relaying in sidelink networks by providing sidelink control information to other sidelink transmitting UE(s) serving as relay stations to forward source UE data to a destination through a synchronous relay mode or asynchronous relay mode. The cooperative relaying through sidelink transmitting UE(s) provides diversity gain and power gain with increased reliability and coverage of the relay link between the sidelink transmitting UE(s) and the destination. Thus, the mechanism may increase uplink coverage to a base station serving as the destination or increase sidelink coverage to a sidelink receiving UE serving as the destination.

As illustrated at <NUM>, the wireless communication device may receive an indication of a set of resources indicating time and frequency resources for a hop transmission path between the plurality of first UEs and the apparatus. The indication of the set of resources may be received, e.g., by the reception component <NUM> of the apparatus <NUM> in <FIG>.

At <NUM>, the wireless communication device may receive, from a plurality of first UEs, a plurality of relay signals that are cooperatively relayed through respective ones of the plurality of first UEs. The plurality of relay signals may be received, e.g., by the reception component <NUM> of the apparatus <NUM> in <FIG>.

In some aspects of receiving the plurality of relay signals, the wireless communication device may receive the first relay signal and the second relay signal based on the set of resources. In some aspects of receiving the plurality of relay signals, the wireless communication device may receive a first relay signal associated with a first relay UE of the plurality of first UEs concurrently with at least a portion of a second relay signal associated with a second relay UE of the plurality of first UEs. In some aspects of receiving the first relay signal, the wireless communication device may receive a common virtual relay identifier in the first relay signal that is equivalent to a relay identifier included in the second relay signal based on a synchronous relay mode between the plurality of first UEs. In some aspects of receiving the plurality of relay signals, the wireless communication device may receive the first relay signal in a same time and frequency resource as the second relay signal in the synchronous relay mode. In other aspects of receiving the plurality of relay signals, the wireless communication device may receive a unique relay identifier in the first relay signal that is different from a relay identifier included in the second relay signal based on an asynchronous relay mode between the plurality of first UEs. In some aspects of receiving the plurality of relay signals, the wireless communication device may receive the first relay signal in a different time and frequency resource than the second relay signal in the asynchronous relay mode. In some aspects of receiving the plurality of relay signals, the wireless communication device can receive the plurality of relay signals as respective unicast transmissions from the plurality of first UEs.

At <NUM>, the wireless communication device may decode each of the plurality of relay signals to recover a respective portion of a groupcast signal originating from a second UE. The plurality of relay signals may be decoded, e.g., by the processor component <NUM> of the apparatus <NUM> in <FIG>. In some aspects, the decoding includes combining the first relay signal with the second relay signal to recover data from the second UE.

The apparatus <NUM> may be a UE or other wireless device that communicates based on sidelink. The apparatus <NUM> includes a cellular baseband processor <NUM> (also referred to as a modem) coupled to a cellular RF transceiver <NUM> and one or more subscriber identity modules (SIM) cards <NUM>, an application processor <NUM> coupled to a secure digital (SD) card <NUM> and a screen <NUM>, a Bluetooth module <NUM>, a wireless local area network (WLAN) module <NUM>, a Global Positioning System (GPS) module <NUM>, and a power supply <NUM>. The cellular baseband processor <NUM> communicates through the cellular RF transceiver <NUM> with other wireless devices, such as a UE <NUM> and/or base station <NUM>/<NUM>. The cellular baseband processor <NUM> further includes a reception component <NUM>, a relay communication manager <NUM>, and a transmission component <NUM>. The relay communication manager <NUM> includes the one or more illustrated components. The components within the relay communication manager <NUM> may be stored in the computer-readable medium / memory and/or configured as hardware within the cellular baseband processor <NUM>. The cellular baseband processor <NUM> may be a component of the device <NUM> or <NUM> and may include the memory <NUM> or <NUM> and/or at least one of the TX processor <NUM> or <NUM>, the RX processor <NUM> or <NUM>, and the controller/processor <NUM> or <NUM>. In one configuration, the apparatus <NUM> may be a modem chip and include just the baseband processor <NUM>, and in another configuration, the apparatus <NUM> may be the entire wireless device (e.g., see the device <NUM> or <NUM> of <FIG>) and include the additional modules of the apparatus <NUM>.

The relay communication manager <NUM> includes a configuration component <NUM>, a resource component <NUM>, a groupcast component <NUM>, a relay mode component <NUM>, a determination component <NUM>, a relay identifier component <NUM> and/or a processor component <NUM> configured to perform the aspects described in connection with methods in <FIG>, <FIG> and/or <FIG>. The apparatus is illustrated as including components to perform the method of <FIG>, <FIG> and/or <FIG>, because the wireless device may operate as a transmitting device at times and may operate as a receiving device at other times. In other examples, the apparatus <NUM> may include components for the method of <FIG> without including components configured to perform the method of <FIG> and/or <FIG>, or may include components for the method of <FIG> without including components configured to perform the method of <FIG> and/or <FIG>, or may include components for the method of <FIG> without including components configured to perform the method of <FIG> and/or <FIG>.

The apparatus <NUM> may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts of <FIG>, <FIG> and/or <NUM>. As such, each block in the aforementioned flowcharts of <FIG>, <FIG> and/or <NUM> may be performed by a component and the apparatus may include one or more of those components.

In one configuration, the apparatus <NUM>, and in particular the cellular baseband processor <NUM>, includes means for receiving, at a first UE from a second UE, a groupcast signal comprising a resource allocation assigned to a plurality of sidelink UEs including the first UE. The apparatus <NUM> may further include means for communicating, with a remote apparatus on a first resource included in the resource allocation, a first relay signal comprising at least a portion of the groupcast signal, the first relay signal corresponding to at least a portion of a second relay signal communicated with the remote apparatus on a second resource included in the resource allocation by at least one other sidelink UE of the plurality of sidelink UEs.

The apparatus <NUM> may further include means for determining a resource allocation assigned to a plurality of second UEs for forwarding data between the first UE and a remote apparatus through a cooperative relay with the plurality of second UEs. The apparatus <NUM> may further include means for transmitting, to the plurality of second UEs on a first resource over a sidelink channel, a groupcast signal comprising the resource allocation.

The apparatus <NUM> may further include means for receiving, from a plurality of first UEs, a plurality of relay signals that are cooperatively relayed through respective ones of the plurality of first UEs. The apparatus <NUM> may further include means for decoding each of the plurality of relay signals to recover a respective portion of a groupcast signal originating from a second UE.

Claim 1:
A system comprising:
a first apparatus (<NUM>) for wireless communication at a first UE (<NUM>) of a plurality of sidelink UEs (<NUM>, <NUM>, <NUM>), the apparatus comprising:
means for receiving, from a second UE (<NUM>), via the transceiver, a groupcast signal comprising a time and frequency resource allocation assigned to the plurality of sidelink UEs including the first UE and the at least one other sidelink UE; and
means for communicating, with a remote apparatus (<NUM>) on a first resource included in the resource allocation, via the transceiver, a first relay signal comprising at least a first portion of the groupcast signal;
a second apparatus (<NUM>) for wireless communication at at least one other sidelink user equipment, UE, (<NUM>) of the plurality of sidelink UEs, the second apparatus comprising:
means for receiving, from the second UE (<NUM>), the groupcast signal comprising the time and frequency resource allocation assigned to the plurality of sidelink UEs including the first UE and the at least one other sidelink UE; and
means for communicating, with the remote apparatus (<NUM>) on a second resource included in the resource allocation, a second relay signal comprising at least a second portion of the groupcast signal.