Patent Description:
The present disclosure relates generally to communication systems, and more particularly, to a method and apparatus for activating a media access control (MAC) control element (CE) (MAC-CE) transmitted over a sidelink relay after waiting an activation time period.

Some aspects of wireless communication may comprise direct communication between devices based on sidelink. There exists a need for further improvements in sidelink technology. Relatedly, document <CIT> describes a method and device for changing the wireless path in a wireless communication system.

Embodiments and aspects that do not fall within the scope of the claims are merely examples used for explanation of the invention.

Accordingly, in one or more examples, the functions described may be implemented in hardware, software, or any combination thereof. By way of example, and not limitation, such computer-readable media can comprise 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 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.

A link between a UE <NUM> and a base station <NUM> or <NUM> may be established as an access link, e.g., using a Uu interface. Other communication may be exchanged between wireless devices based on sidelink. For example, some UEs <NUM> may communicate with each other directly using a device-to-device (D2D) communication link <NUM>. In some examples, the D2D communication link <NUM> may use the DL/UL WWAN spectrum.

Some examples of sidelink communication may include vehicle-based communication devices that can communicate from 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 vehicle-to-anything (V2X) communications. Sidelink communication may be based on V2X or other D2D communication, such as Proximity Services (ProSe), etc. In addition to UEs, sidelink communication may also be transmitted and received by other transmitting and receiving devices, such as Road Side Unit (RSU) <NUM>, etc. Sidelink communication may be exchanged using a PC5 interface, such as described in connection with the example in <FIG>. Although the following description, including the example slot structure of <FIG>, may provide examples for sidelink 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.

Referring again to <FIG>, in certain aspects, a UE <NUM>, or other device communicating based on sidelink, may include a sidelink relay MAC-CE component <NUM> configured to receive an activation request for a command in association with a third UE, the activation request being received in a first MAC-CE relayed from a second UE, transmit, to the second UE and in response to the activation request, a second MAC-CE including an activation response to the third UE, and activate the command after transmitting the activation response.

Similarly, beamforming may be applied for sidelink communication, e.g., between UEs.

Although this example is described for the base station <NUM> and UE <NUM>, the aspects may be similarly applied between a first and second device (e.g., a first and second UE) for sidelink communication.

<FIG> illustrate a frame structure, and the aspects of the present disclosure may be applicable to other wireless communication technologies, which may have a different frame structure and/or different channels. Each slot may include <NUM> or <NUM> symbols, depending on whether the cyclic prefix (CP) is normal or extended. For normal CP, each slot may include <NUM> symbols, and for extended CP, each slot may include <NUM> symbols. The symbols on DL may be CP orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbols. The number of slots within a subframe is based on the CP and the numerology. The numerology defines the subcarrier spacing (SCS) and, effectively, the symbol length/duration, which is equal to <NUM>/SCS.

For normal CP (<NUM> symbols/slot), different numerologies µ <NUM> to <NUM> allow for <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> slots, respectively, per subframe. For extended CP, the numerology <NUM> allows for <NUM> slots per subframe. Accordingly, for normal CP and numerology µ, there are <NUM> symbols/slot and <NUM>µ slots/subframe. <FIG> provide an example of normal CP with <NUM> symbols per slot and numerology µ=<NUM> with <NUM> slots per subframe. The slot duration is <NUM>, the subcarrier spacing is <NUM>, and the symbol duration is approximately <NUM>. Within a set of frames, there may be one or more different bandwidth parts (BWPs) (see <FIG>) that are frequency division multiplexed. Each BWP may have a particular numerology and CP (normal or extended).

The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) (e.g., <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> CCEs), each CCE including six RE groups (REGs), each REG including <NUM> consecutive REs in an OFDM symbol of an RB. A PDCCH within one BWP may be referred to as a control resource set (CORESET). A UE is configured to monitor PDCCH candidates in a PDCCH search space (e.g., common search space, UE-specific search space) during PDCCH monitoring occasions on the CORESET, where the PDCCH candidates have different DCI formats and different aggregation levels. Additional BWPs may be located at greater and/or lower frequencies across the channel bandwidth. Based on the PCI, the UE can determine the locations of the DM-RS. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block (also referred to as SS block (SSB)).

The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and hybrid automatic repeat request (HARQ) acknowledgment (ACK) (HARQ-ACK) feedback (i.e., one or more HARQ ACK bits indicating one or more ACK and/or negative ACK (NACK)).

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

<FIG> includes diagrams <NUM> and <NUM> illustrating example aspects of slot structures that may be used for sidelink communication (e.g., between UEs <NUM>, RSU <NUM>, etc.). The slot structure may be within a <NUM>/NR frame structure in some examples. In other examples, the slot structure may be within an LTE frame structure. The example slot structure in <FIG> is merely one example, and other sidelink communication may have a different frame structure and/or different channels for sidelink communication. Diagram <NUM> illustrates a single resource block of a single slot transmission, e.g., which may correspond to a <NUM> transmission time interval (TTI). A physical sidelink control channel may be configured to occupy multiple physical resource blocks (PRBs), e.g., <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> PRBs. The PSCCH may be limited to a single sub-channel. A PSCCH duration may be configured to be <NUM> symbols or <NUM> symbols, for example. A sub-channel may include <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> PRBs, for example. The resources for a sidelink transmission may be selected from a resource pool including one or more subchannels. As a non-limiting example, the resource pool may include between <NUM>-<NUM> subchannels. A PSCCH size may be established for a resource pool, e.g., as between <NUM>-<NUM>% of one subchannel for a duration of <NUM> symbols or <NUM> symbols. The diagram <NUM> in <FIG> illustrates an example in which the PSCCH occupies about <NUM>% of a subchannel, as one example to illustrate the concept of PSCCH occupying a portion of a subchannel. The PSSCH occupies at least one subchannel. The PSCCH may include a first portion of sidelink control information (SCI), and the PSSCH may include a second portion of SCI in some examples.

Each time slot may include a resource block (RB) (also referred to as physical RBs (PRBs)) that extends <NUM> consecutive subcarriers. As illustrated in <FIG>, some of the REs may include control information in a PSCCH and some REs may include demodulation RS (DMRS). At least one symbol may be used for feedback. <FIG> illustrates examples with two symbols for a physical sidelink feedback channel (PSFCH) with adjacent gap symbols. A symbol prior to and/or after the feedback may be used for turnaround between reception of data and transmission of the feedback. 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 data, DMRS, SCI, feedback, gap symbols, and/or LBT symbols may be different than the example illustrated in <FIG>. Multiple slots may be aggregated together in some aspects.

<FIG> illustrates an example <NUM> of sidelink communication between devices. The communication may be based on a slot structure including aspects described in connection with <FIG>. For example, the UE <NUM> may transmit a sidelink transmission <NUM>, e.g., including a control channel (e.g., a PSCCH) and/or a corresponding data channel (e.g., a PSSCH), that may be received by UEs <NUM>, <NUM>, <NUM>. A control channel may include information (e.g., sidelink control information (SCI)) for decoding the data channel including reservation information, such as information about time and/or frequency resources that are reserved for the data channel transmission. For example, the SCI may indicate a number of TTIs, as well as the RBs that will be occupied by the data transmission. The SCI may also be used by receiving devices to avoid interference by refraining from transmitting on the reserved resources. The UEs <NUM>, <NUM>, <NUM>, <NUM> may each be capable of sidelink transmission in addition to sidelink reception. Thus, UEs <NUM>, <NUM>, <NUM> are illustrated as transmitting sidelink transmissions <NUM>, <NUM>, <NUM>, <NUM>. The sidelink transmissions <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be unicast, broadcast, or multicast to nearby devices. For example, UE <NUM> may transmit sidelink transmissions <NUM>, <NUM> intended for receipt by other UEs within a range <NUM> of UE <NUM>, and UE <NUM> may transmit sidelink transmission <NUM>. Additionally or alternatively, RSU <NUM> may receive communication from and/or transmit communication <NUM> to UEs <NUM>, <NUM>, <NUM>, <NUM>. One or more of the UEs <NUM>, <NUM>, <NUM>, <NUM> or the RSU <NUM> may include the sidelink relay MAC-CE component <NUM> as described in connection with <FIG>.

The MAC-CE is a command from one network device to another network device. The network device may be UEs and base station. Accordingly, the UE and the base station may send command messages in MAC-CE to the UE and/or the base station. Particularly, the MAC-CEs between UEs may be transmitted through a sidelink communication. The MAC-CE may provide feedback through HARQ messaging, which may provide improved reliability and increased latency. The receiver may provide HARQ ACK to the transmitter to provide confirmation that the command has been successfully received through the MAC-CE. Alternatively, the command messages may be transmitted via DCI on DL or UCI (over a PUCCH or a PUSCH) on UL. Transmitting the command messages via DCI on DL or UCI on UL does not provide HARQ messaging (e.g., ACK / negative ACK (NACK)). Therefore, the command messages transmitted via DCI on DL or UCI on UL may have lower latency, but may be less reliable.

The MAC-CE may be transmitted over sidelink communication. In LTE communication, a sidelink (SL) buffer status report (BSR) MAC-CE (SL-BSR MAC-CE) may be transmitted on a Uu link to indicate buffer-status of the sidelink traffic. For NR vehicle-to-everything (V2X) (NRV2X), a CSI report may be agreed to be transmitted over a sidelink MAC-CE. By transmitting the sidelink MAC-CE including the CSI report, a UE may not implement a receiver for UCI multiplexing.

To implement more advanced use cases, more sidelink-related MAC-CEs may be needed. For example, the MAC-CEs transmitted over either the Uu link or the sidelink communication may carry sidelink-related information. In the case of sidelink relaying, the MAC-CEs may indicate the relayed traffic and/or the originating traffic. In the case of the Uu-PC5 slot-aggregation, special handling may be provided for the MAC-CE, and the MAC-CE may indicate which code block groups (CBGs) was transmitted through which link.

The Uu link MAC-CEs (DL or UL) relayed via the sidelink communication may include appended relaying/routing information. The relaying/routing information may be separately indicated for RRC/MAC-CE/DCI or their sidelink equivalents. The replaying information may include one or more of a source node, a destination node, or a transit route.

In case the last leg of a relay is the Uu link, the routing information may be removed, or some or all of it may be kept (e.g., a source ID) at the last leg. In case of Uu+PC5 slot-aggregation, the last leg may be the Uu + PC5 link, and the routing information indication may be different compared to the Uu-only link.

The contents of the MAC-CE may include commands to a target network device (e.g., a receiving UE) to perform or activate a certain function. The MAC-CEs transmitted on the SL may include SL-related content such as SL-CSI, SL timing advance (SL-TA) (e.g., for out-of-coverage (OOC)), SL transmit power control (TPC) (SL-TPC), SL scheduling request (SR)/buffer status report (B SR)/power headroom report (PHR), activation/deactivation of SL semi-persistent scheduling (SL-SPS)/carrier grade (CG) and/or aperiodic/semi-persistent (A/SP) SL-CSI-RS/SRS (A/SP SL-CSI-RS/SRS). When the MAC-CEs including the above provided content are relayed over SL, the routing information may be padded/removed as proffered regarding the SL-relayed Uu MAC-CE.

The MAC-CEs sent on Uu link with SL-related content (e.g., SL-BSR of LTE) may include the SL-PHR, the TPC, a recommended bit-rate, channel busy ratio (CBR)/channel occupation ratio (CR), and the base station-relayed MAC-CEs as proffered regarding the MAC-CEs transmitted on the SL with SL-related content.

A 'header' MAC-CE may indicate which CBGs are transmitted through which link (the Uu link or the PC5 link). The header MAC-CE may also indicate locations of other MAC-CEs, particularly, whether they come from the Uu link or the PC5 link.

The MAC-CE may have an activation time. On the Uu link, some of the MAC-CEs such as the UL MAC-CEs, DL TA and a recommended bit rate may not have the activation time, but many MAC-CEs may have the activation time based on the time of the ACK transmission. For example, an activation time may be three ms or N slots after the transmission of an ACK. The counting of time may either include or exclude TA commands received during the counting. The ACK Tx may refer to an ACK for the entire TB. In general, UL MAC-CEs may not have an activation time, as how to react to the UL MAC-CE may be determined by the base station implementation.

On the SL communication, the MAC-CEs sent to the base station with the SL-related content may be treated like the Uu UL MAC-CEs, and it may be determined by the base station implementation to determine how to react to the MAC-CEs. The MAC-CEs sent to a UE over SL or over DL (with SL-related content) may be treated like Uu DL MAC-CEs. Accordingly, the activation time may be based on an ACK. The activation time may be different for the MAC-CEs sent over the SL and the MAC-CE sent over the DL. Furthermore, MAC-CEs relayed to the UE through relaying UE may need special consideration.

The MAC-CEs may be relayed to a receiving UE through the relaying UE, and different activation time may be configured for the receiving UE. The ACK may be transmitted in response to successfully receiving the MAC-CE. In case the ACK is not relayed, the ACK may be directly transmitted from the receiving UE to the originating UE, the UE from which the MAC-CE originated. The receiving UE may follow ACK timing, and may have the activation time based on the time of the ACK transmission. For example, the receiving UE may wait three ms after transmitting the ACK to the originating UE before activating the MAC-CE.

In case the ACK is relayed back to the originating UE through the relaying UE, the receiving UE may follow a timing dependent on the time delay caused by the hopping of the relayed MAC-CE, since a predetermined time delay may not be sufficient compared to the directly transmitted ACK. For example, the receiving UE may use X ms for an activation time, where X depends on a number of hops. Since the number of hops may be dynamic and the receiving UE may not know the number of signal hops, this information may be separately indicated to the receiving UE (e.g., as a part of the ACK or in DCI/MAC-CE/RRC). For example, the receiving UE may use an 'expected' number of hops instead as preconfigured.

In another example, the receiving UE may follow the timing of the last hop of an ACK. The receiving UE may know the timing based on when it receives the ACK. However, the originating UE may not know this time. Again, the receiving UE may use a preconfigured/expected timing which is based on the number of the hops, and the preconfigured/expected timing may become equivalent to the option of configuring the X ms of activation time. When the ACK may be relayed by multiple routes, the number of hops to determine the 'X ms' may be based on the shortest route or the longest route, where the length of the route refers to the number of hops.

When an originating UE transmits a MAC-CE including a command to a receiving UE via a relay UE, the receiving UE may determine an activation time to activate the command received in the MAC-CE from the originating UE via the relay UE.

In one example, when the receiving UE sends the ACK straight back to the originating UE, the receiving UE may follow the approach proffered regarding the Uu link. In one example, when the receiving UE sends an ACK relayed via the relay UE to the originating UE, the receiving UE may determine the activation time. First, the receiving UE may wait for an activation time period of X milliseconds corresponding to the hops between the receiving UE and the originating UE. Second, the receiving UE may increase the activation time period by adding an additional offset of Y milliseconds configured to allow time to relay ACK from the relay UE to the originating UE. Third, when the ACK to the originating UE itself is sent in a packet (e.g., a PSSCH carrying a second MAC-CE), the second MAC-CE may also be ACKed (e.g., the relay UE may send an ACK to the receiving UE to indicate the receipt of the second MAC-CE), and further the relay UE may send an ACK to the receiving UE to indicate the successful relaying of the second MAC-CE to the originating UE. Fourth, the MAC-CE from the originating UE may be activated after X' milliseconds after the transmission of a PSSCH carrying the MAC-CE based ACK (for the MAC-CE received from the originating UE) by the receiving UE. Fifth, the MAC-CE from the originating UE may be activated after X'' milliseconds after the successful receipt of a HARQ-ACK for the successful transmission of the PSSCH transmitted to the originating UE.

<FIG> illustrates an example <NUM> of a wireless communication. The example <NUM> includes a first UE <NUM>, a second UE <NUM>, and a third UE <NUM>. The third UE <NUM> (or UE3) may transmit a MAC-CE to a first UE <NUM> (or UE1) using a second UE <NUM> (or UE2) as a relay UE. The MAC-CE from the third UE <NUM> may request the first UE <NUM> to transmit a response MAC-CE based ACK to the third UE <NUM>, instead of or in addition to the HARQ ACK. The response MAC-CE transmitted by the first UE <NUM> to the third UE <NUM> need not be an ACK.

First, at <NUM>, the third UE <NUM> may transmit a first MAC-CE (or a MAC-CE1) intended for the first UE <NUM> to the second UE <NUM>. At <NUM>, the second UE <NUM> in turn may relay the first MAC-CE to the first UE <NUM>.

After successfully receiving the first MAC-CE from the third UE <NUM> via the second UE <NUM>, the first UE <NUM> may transmit a PSSCH with a second MAC-CE (or a MAC-CE2) to the third UE <NUM> in response to the first MAC-CE. Here, the second MAC-CE may include the ACK for the first MAC-CE, indicating the successful reception of the first MAC-CE.

The PSSCH <NUM> illustrates an example of the PSSCH transmitted from the first UE <NUM> including the second MAC-CE, the second MAC-CE including the MAC-CE based ACK for the first MAC-CE, indicating the successful reception of the first MAC-CE.

At <NUM>, the first UE <NUM> may transmit the PSSCH with the second MAC-CE to the third UE <NUM> by transmitting the PSSCH by relaying the second MAC-CE via the second UE <NUM>. At <NUM>, the second UE <NUM> may relay the PSSCH with the second MAC-CE to the third UE <NUM>.

After successfully receiving the second MAC-CE from the first UE <NUM> via the second UE <NUM>, the third UE <NUM> may transmit a HARQ ACK indicating the successful reception of the second MAC-CE. At <NUM>, the third UE <NUM> may transmit the HARQ ACK indicating the successful reception of the second MAC-CE to the second UE <NUM>. At <NUM>, the second UE <NUM> may relay the HARQ ACK indicating the successful reception of the second MAC-CE to the first UE <NUM>.

<FIG> is a call-flow diagram <NUM> of wireless communication. The call-flow diagram <NUM> may include a first UE <NUM>, a second UE <NUM>, and a third UE <NUM>. The first UE <NUM> may receive an activation request from the third UE <NUM> relayed via the second UE <NUM>, and transmit an activation response to the third UE <NUM> and activate the received activation request after a time period.

The third UE <NUM> (or UE3; e.g., first UE <NUM>) may transmit a first MAC-CE (i.e., MAC-CE1) to the first UE <NUM> (or UE1; e.g., third UE <NUM>) using the second UE <NUM> (or UE2; e.g., second UE <NUM>) as a relay UE. The first MAC-CE from the third UE <NUM> may instruct the first UE <NUM> to transmit a MAC-CE based ACK to the third UE <NUM>, instead of or in addition to the HARQ ACK. At <NUM>, the third UE <NUM> may transmit, to the second UE <NUM>, a first MAC-CE (or MAC-CE1) intended for the first UE <NUM> (e.g., at step <NUM>). The first MAC-CE may include the activation request for a command associated with the first UE <NUM>.

At <NUM>, the second UE <NUM> may relay, from the third UE <NUM> to the first UE <NUM>, the first MAC-CE including the activation request for a command associated with the first UE <NUM> (e.g., at step <NUM>). The first UE <NUM> may receive the activation request for the command in association with the third UE <NUM>, the activation request being received in the first MAC-CE relayed from the second UE <NUM> (e.g., at step <NUM>). The activation request may be received through a PSSCH.

Upon successfully receiving the first MAC-CE from the third UE <NUM>, at <NUM>, the first UE <NUM> may transmit, to the second UE <NUM> and in response to the activation request, a second MAC-CE including an activation response to the third UE <NUM> (e.g., at step <NUM>). The activation response may be transmitted through the PSSCH. The PSSCH may include a MAC-CE based ACK intended for the third UE <NUM> (e.g., the PSSCH <NUM>). That is, the PSSCH transmitted from the first UE <NUM> may include the second MAC-CE including the MAC-CE based ACK for the first MAC-CE, indicating the successful reception of the first MAC-CE intended for the third UE <NUM>.

At <NUM>, the second UE <NUM> may transmit a HARQ ACK indicating the successful reception of the PSSCH from the first UE <NUM>. The first UE <NUM> may receive a HARQ ACK in association with the second UE <NUM> from the second UE <NUM> in response to the activation response transmitted at <NUM>.

At <NUM>, the second UE <NUM> may relay, from the first UE <NUM> to the third UE <NUM>, the second MAC-CE received at <NUM>, the second MAC-CE including the activation response to the third UE <NUM> (e.g., at step <NUM>).

Upon successfully receiving the PSSCH including the MAC-CE based ACK from the first UE <NUM> via the second UE <NUM>, the third UE <NUM> may transmit a HARQ ACK indicating the successful reception of the PSSCH including the MAC-CE based ACK. At <NUM>, the third UE <NUM> may transmit the HARQ ACK for the first UE <NUM> in response to the successful reception of the PSSCH from the first UE <NUM> relayed via the second UE <NUM> (e.g., at step <NUM>).

At <NUM>, the second UE <NUM> may relay, from the third UE <NUM> to the first UE <NUM>, a HARQ ACK in association with the third UE <NUM> in response to the activation response (e.g., at step <NUM>). The first UE <NUM> may receive the HARQ ACK in association with the third UE <NUM> from the second UE <NUM> in response to the activation response transmitted at <NUM> (e.g., at step <NUM>).

At <NUM>, the first UE <NUM> may determine a time period before activating the first MAC-CE received at <NUM>. In one aspect, the first UE <NUM> may determine the time period to wait after receiving the HARQ ACK in association with the third UE <NUM> and before activating the command. In another aspect, the first UE <NUM> may determine the time period to wait after receiving the HARQ ACK in association with the second UE <NUM> and before activating the command. In another aspect, the first UE <NUM> may determine the time period after the transmission of the second MAC-CE including the activation response and before activating the command based on a number of hops between the third UE <NUM> and the first UE <NUM> through which the activation request traveled, the number of hops being greater than or equal to one.

In one aspect, the time period for the first UE <NUM> to wait before activating the first MAC-CE may be determined based on the transmission of the PSSCH for the third UE <NUM> at <NUM>. That is, the first UE <NUM> may determine the time period as X milliseconds based on the number of hops from the first UE <NUM> to the third UE <NUM>. The first UE <NUM> may activate the command transmitted in the first MAC-CE after the time period of X milliseconds after the transmission of the PSSCH containing the MAC-CE based ACK to the third UE <NUM> at <NUM>.

In another aspect, the time period for the first UE <NUM> to wait before activating the first MAC-CE may be determined based on the reception of the HARQ ACK in response to the PSSCH, the HARQ ACK transmitted from the third UE <NUM> via the second UE <NUM> at <NUM>. That is, the first UE <NUM> may determine the time period as Y milliseconds. The first UE <NUM> may activate the command transmitted in the first MAC-CE after the time period of Y milliseconds after the reception of the HARQ ACK from the third UE <NUM> via the second UE <NUM> at <NUM>, the HARQ ACK indicating the successful reception of the PSSCH at the third UE <NUM>.

In another aspect, the time period for the first UE <NUM> to wait before activating the first MAC-CE may be determined based on the reception of the HARQ ACK in response to the PSSCH, the HARQ ACK transmitted from the second UE <NUM> at <NUM>. That is, the first UE <NUM> may determine the time period as Z milliseconds. The first UE <NUM> may activate the command transmitted in the first MAC-CE after the time period of Z milliseconds after the reception of the HARQ ACK from the second UE <NUM> at <NUM>, the HARQ ACK indicating the successful reception of the PSSCH at the second UE <NUM>.

At <NUM>, the first UE <NUM> may activate the command after transmitting the activation response. That is, the first UE <NUM> may activate the first MAC-CE received from the third UE <NUM> at <NUM> after the time period determined at <NUM>. In one aspect, the command may be activated after the time period from receiving the HARQ ACK in association with the third UE at <NUM>. In another aspect, the command may be activated after the time period from receiving the HARQ ACK in association with the second UE at <NUM>. In another aspect, the command may be activated after a time period from a transmission of the second MAC-CE including the activation response at <NUM>. The command may be activated before the HARQ ACK is received, or the command may be activated after the HARQ ACK is received.

<FIG> is a flowchart <NUM> of a method of wireless communication. The method may be performed by a UE (e.g., the UE <NUM>; the first UE <NUM>/<NUM>; the apparatus <NUM>). The UE may receive an activation request from a third UE relayed via a second UE, and transmit an activation response to the third UE and activate the received activation request after a time period.

At <NUM>, the UE receives the activation request for the command in association with the third UE, the activation request being received in the first MAC-CE relayed from the second UE. The activation request may be received through a PSSCH. For example, at <NUM>, the first UE <NUM> may receive the activation request for the command in association with the third UE <NUM>, the activation request being received in the first MAC-CE relayed from the second UE <NUM>. Furthermore, <NUM> may be performed by a MAC-CE managing component <NUM>.

At <NUM>, the UE, upon successfully receiving the first MAC-CE from the third UE at, transmits, to the second UE and in response to the activation request, a second MAC-CE including an activation response to the third UE. That is, the PSSCH transmitted from the UE may include the second MAC-CE including the MAC-CE based ACK for the first MAC-CE, indicating the successful reception of the first MAC-CE intended for the third UE. For example, at <NUM>, the first UE <NUM> may, upon successfully receiving the first MAC-CE from the third UE at <NUM>, transmit, to the second UE <NUM> and in response to the activation request, a second MAC-CE including an activation response to the third UE <NUM>. Furthermore, <NUM> may be performed by the MAC-CE managing component <NUM>.

At <NUM>, the UE may receive a HARQ ACK in association with the second UE from the second UE in response to the activation response transmitted at <NUM>. For example, at <NUM>, the first UE <NUM> may receive a HARQ ACK in association with the second UE <NUM> from the second UE <NUM> in response to the activation response transmitted at <NUM>. Furthermore, <NUM> may be performed by a HARQ managing component <NUM>.

At <NUM>, the UE may receive the HARQ ACK in association with the third UE from the second UE <NUM> in response to the activation response transmitted at <NUM>. For example, at <NUM>, the first UE <NUM> may receive the HARQ ACK in association with the third UE <NUM> from the second UE <NUM> in response to the activation response transmitted at <NUM>. Furthermore, <NUM> may be performed by the HARQ managing component <NUM>.

At <NUM>, the UE may determine a time period before activating the first MAC-CE received at <NUM>. In one aspect, the UE may determine the time period to wait after receiving the HARQ ACK in association with the third UE and before activating the command. In another aspect, the UE may determine the time period to wait after receiving the HARQ ACK in association with the second UE and before activating the command. In another aspect, the UE may determine the time period after the transmission of the second MAC-CE including the activation response and before activating the command based on a number of hops between the third UE and the UE through which the activation request traveled, the number of hops being greater than or equal to one. For example, at <NUM>, the first UE <NUM> may determine a time period before activating the first MAC-CE received at <NUM>. Furthermore, <NUM> may be performed by an activation time period component <NUM>.

In one aspect, the time period for the UE to wait before activating the first MAC-CE may be determined based on the transmission of the PSSCH for the third UE at <NUM>. That is, the UE may determine the time period as X milliseconds based on the number of hops from the UE to the third UE. The UE may activate the command transmitted in the first MAC-CE after the time period of X milliseconds after the transmission of the PSSCH containing the MAC-CE based ACK to the third UE at <NUM>.

In another aspect, the time period for the UE to wait before activating the first MAC-CE may be determined based on the reception of the HARQ ACK in response to the PSSCH, the HARQ ACK transmitted from the third UE via the second UE at <NUM>. That is, the UE may determine the time period as Y milliseconds. The UE may activate the command transmitted in the first MAC-CE after the time period of Y milliseconds after the reception of the HARQ ACK from the third UE via the second UE at <NUM>, the HARQ ACK indicating the successful reception of the PSSCH at the third UE.

In another aspect, the time period for the UE to wait before activating the first MAC-CE may be determined based on the reception of the HARQ ACK in response to the PSSCH, the HARQ ACK transmitted from the second UE at <NUM>. That is, the UE may determine the time period as Z milliseconds. The UE may activate the command transmitted in the first MAC-CE after the time period of Z milliseconds after the reception of the HARQ ACK from the second UE at <NUM>, the HARQ ACK indicating the successful reception of the PSSCH at the second UE.

At <NUM>, the UE activates the command after transmitting the activation response. That is, the UE may activate the first MAC-CE received from the third UE at <NUM> after the time period determined at <NUM>. In one aspect, the command may be activated after the time period from receiving the HARQ ACK in association with the third UE at <NUM>. In another aspect, the command may be activated after the time period from receiving the HARQ ACK in association with the second UE at <NUM>. In another aspect, the command may be activated after a time period from a transmission of the second MAC-CE including the activation response at <NUM>. The command may be activated before the HARQ ACK is received, or the command may be activated after the HARQ ACK is received. For example, at <NUM>, the first UE <NUM> may activate the command after transmitting the activation response. Furthermore, <NUM> may be performed by a command component <NUM>.

At <NUM>, the UE activates the command after transmitting the activation response. That is, the UE may activate the first MAC-CE received from the third UE at <NUM> after the time period determined. In one aspect, the command may be activated after the time period from receiving the HARQ ACK in association with the third UE. In another aspect, the command may be activated after the time period from receiving the HARQ ACK in association with the second UE. In another aspect, the command may be activated after a time period from a transmission of the second MAC-CE including the activation response at <NUM>. The command may be activated before the HARQ ACK is received, or the command may be activated after the HARQ ACK is received. For example, at <NUM>, the first UE <NUM> may activate the command after transmitting the activation response. Furthermore, <NUM> may be performed by a command component <NUM>.

<FIG>, which is useful for an understanding of the invention, is a flowchart <NUM> of a method of wireless communication. The method may be performed by a UE (e.g., the UE <NUM>; the second UE <NUM>/<NUM>; the apparatus <NUM>). The UE may relay an activation request from a third UE to a first UE, and relay an activation response from the first UE to the third UE.

At <NUM>, the UE may receive, from the third UE, a first MAC-CE intended for the first UE. The first MAC-CE may include the activation request for a command associated with the first UE. For example, at <NUM>, the second UE <NUM> may receive, from the third UE <NUM>, a first MAC-CE intended for the first UE <NUM>. Furthermore, <NUM> may be performed by a MAC-CE managing component <NUM>.

At <NUM>, the UE may relay, from the third UE to the first UE, the first MAC-CE including the activation request for a command associated with the first UE. The activation request may be received through a PSSCH. For example, at <NUM>, the second UE <NUM> may relay, from the third UE <NUM> to the first UE <NUM>, the first MAC-CE including the activation request for a command associated with the first UE <NUM>. Furthermore, <NUM> may be performed by the MAC-CE managing component <NUM>.

At <NUM>, the UE may receive, from the first UE, a second MAC-CE including an activation response to the third UE. The activation response may be transmitted through the PSSCH. The PSSCH may include a MAC-CE based ACK intended for the third UE. That is, the PSSCH transmitted from the first UE may include the second MAC-CE including the MAC-CE based ACK for the first MAC-CE, indicating the successful reception of the first MAC-CE intended for the third UE. For example, at <NUM>, the second UE <NUM> may receive, from the first UE <NUM>, a second MAC-CE including an activation response to the third UE <NUM>. Furthermore, <NUM> may be performed by the MAC-CE managing component <NUM>.

At <NUM>, the UE may transmit a HARQ ACK indicating the successful reception of the PSSCH from the first UE. For example, at <NUM>, the second UE <NUM> may transmit a HARQ ACK indicating the successful reception of the PSSCH from the first UE <NUM>. Furthermore, <NUM> may be performed by a HARQ managing component <NUM>.

At <NUM>, the UE may relay, from the first UE to the third UE, the second MAC-CE received at <NUM>, the second MAC-CE including the activation response to the third UE. For example, at <NUM>, the second UE <NUM> may relay, from the first UE <NUM> to the third UE <NUM>, the second MAC-CE received at <NUM>, the second MAC-CE including the activation response to the third UE <NUM>. Furthermore, <NUM> may be performed by the MAC-CE managing component <NUM>.

At <NUM>, the UE may receive the HARQ ACK for the first UE in response to the successful reception of the PSSCH from the first UE relayed via the second UE. For example, at <NUM>, the second UE <NUM> may receive the HARQ ACK for the first UE <NUM> in response to the successful reception of the PSSCH from the first UE <NUM> relayed via the second UE <NUM>. Furthermore, <NUM> may be performed by the HARQ managing component <NUM>.

At <NUM>, the UE may relay, from the third UE to the first UE, a HARQ ACK in association with the third UE in response to the activation response. For example, at <NUM>, the second UE <NUM> may relay, from the third UE <NUM> to the first UE <NUM>, a HARQ ACK in association with the third UE <NUM> in response to the activation response. Furthermore, <NUM> may be performed by the HARQ managing component <NUM>.

The apparatus <NUM> may be a UE, or another device configured to transmit and/or receive sidelink communication. The apparatus1202 includes a baseband processor <NUM> (also referred to as a modem) coupled to a RF transceiver <NUM>. In some aspects, the baseband processor <NUM> may be a cellular baseband processor and/or the RF transceiver <NUM> may be a cellular RF transceiver. The apparatus <NUM> may further include 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/or a power supply <NUM>. The baseband processor <NUM> communicates through the RF transceiver <NUM> with the UE <NUM> and/or BS <NUM>/<NUM>. The baseband processor <NUM> may include a computer-readable medium / memory. The baseband processor <NUM> is responsible for general processing, including the execution of software stored on the computer-readable medium / memory. The software, when executed by the baseband processor <NUM>, causes the baseband processor <NUM> to perform the various functions described in the present application. The computer-readable medium / memory may also be used for storing data that is manipulated by the baseband processor <NUM> when executing software. The baseband processor <NUM> further includes a reception component <NUM>, a communication manager <NUM>, and a transmission component <NUM>. The components within the communication manager <NUM> may be stored in the computer-readable medium / memory and/or configured as hardware within the baseband processor <NUM>. The baseband processor <NUM> may be a component of the device <NUM> and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <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 UE (e.g., see <NUM> of <FIG>) and include the additional modules of the apparatus <NUM>.

The communication manager <NUM> includes a MAC-CE managing component <NUM> that is configured to receive the activation request for the command in association with the third UE, transmit a second MAC-CE including an activation response to the third UE, receive, from the third UE, a first MAC-CE intended for the first UE, relay, from the third UE to the first UE, the first MAC-CE including the activation request for a command associated with the first UE, receive, from the first UE, a second MAC-CE including an activation response to the third UE, and relay, from the first UE to the third UE the second MAC-CE including the activation response to the third UE, e.g., as described in connection with <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. The communication manager <NUM> further includes a HARQ managing component <NUM> that is configured to receive a HARQ ACK in association with the second UE from the second UE in response to the activation response, receive the HARQ ACK in association with the third UE from the second UE in response to the activation response transmitted, transmit a HARQ ACK indicating the successful reception of the PSSCH from the first UE, receive the HARQ ACK for the first UE in response to the successful reception of the PSSCH from the first UE relayed via the second UE, and relay a HARQ ACK in association with the third UE in response to the activation response, e.g., as described in connection with <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The communication manager <NUM> further includes an activation time period component <NUM> that is configured to determine a time period before activating the first MAC-CE received, e.g., as described in connection with <NUM>. The communication manager <NUM> further includes a command component <NUM> that is configured to activate the command after transmitting the activation response, e.g., as described in connection with <NUM> and <NUM>.

The apparatus may include additional components that perform each of the blocks of the algorithm in the flowcharts of <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>. As such, each block in the flowcharts of <FIG>, <FIG>, <FIG>, <FIG>, and <FIG> 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 baseband processor <NUM>, includes means for receiving an activation request for a command in association with a third UE, the activation request being received in a first MAC-CE) relayed from a second UE, means for transmitting, to the second UE and in response to the activation request, a second MAC-CE including an activation response to the third UE, and means for activating the command after transmitting the activation response. The apparatus <NUM> includes means for receiving a HARQ acknowledgment (ACK) in association with the third UE from the second UE in response to the transmitted activation response, and means for determining the time period to wait after receiving the HARQ ACK in association with the third UE and before activating the command, means for receiving a HARQ acknowledgment (ACK) in association with the second UE from the second UE in response to the transmitted activation response, and means for determining the time period to wait after receiving the HARQ ACK in association with the second UE and before activating the command. The apparatus <NUM> includes means for determining the time period after the transmission of the second MAC-CE including the activation response and before activating the command based on a number of hops between the third UE and the first UE through which the activation request traveled, the number of hops being greater than or equal to one, and the apparatus <NUM> includes means for receiving a HARQ acknowledgment (ACK) in association with the third UE from the second UE in response to the transmitted activation response. The apparatus <NUM> includes means for relaying, from the third UE to the first UE, a first media access control (MAC) control element (CE) (MAC-CE) including an activation request for a command associated with the first UE, means for relaying, from the first UE to the third UE, a second MAC-CE including an activation response to the third UE, and means for relaying, from the third UE to the first UE, a HARQ ACK in association with the third UE in response to the relayed activation response. The means may be one or more of the components of the apparatus <NUM> configured to perform the functions recited by the means. As described herein, the apparatus <NUM> may include the TX Processor <NUM>, the RX Processor <NUM>, and the controller/processor <NUM>. As such, in one configuration, the means may be the TX Processor <NUM>, the RX Processor <NUM>, and the controller/processor <NUM> configured to perform the functions recited by the means.

The apparatus of wireless communication may include a UE configured to activate a MAC-CE transmitted over an SL relay after waiting a time period by receiving an activation request for a command in association with a second UE, the activation request being received in a first MAC-CE relayed from a third UE, transmitting, to the third UE and in response to the activation request, a second MAC-CE including an activation response to the second UE, and activating the command after transmitting the activation response. In one example, the UE may be further configured to receive an HARQ ACK in association with the second UE from the third UE in response to the transmitted activation response, wait a time period after receiving the HARQ ACK in association with the second UE and before activating the command, and determine the time period to wait after receiving the HARQ ACK in association with the second UE and before activating the command. In one example, the UE may receive the HARQ ACK in association with the third UE from the third UE in response to the transmitted activation response, wait a time period after receiving the HARQ ACK in association with the third UE and before activating the command, and determine the time period to wait after receiving the HARQ ACK in association with the third UE and before activating the command. In one example, the UE may wait a time period after transmission of the second MAC-CE including the activation response before activating the command, determine the time period to wait after the transmission of the second MAC-CE including the activation response and before activating the command based on a number of hops between the second UE and the first UE through which the activation request traveled, the number of hops being greater than or equal to one, and receive an HARQ ACK in association with the second UE from the third UE in response to the transmitted activation response. Here, the command may be activated either before or after receiving the HARQ ACK. Here, the activation request is received through a PSSCH, and the activation response is transmitted through the PSSCH. The UE may include an ACK in the activation response.

Claim 1:
An apparatus for wireless communication at a first user equipment, UE (<NUM>, <NUM>), comprising:
means for receiving an activation request for a command in association with a third UE (<NUM>, <NUM>), the activation request being received in a first media access control, MAC, control element, CE, MAC-CE (<NUM>, <NUM>), relayed from a second UE (<NUM>, <NUM>);
means for transmitting, to the second UE (<NUM>, <NUM>) and in response to the activation request, a second MAC-CE (<NUM>, <NUM>) including an activation response to the third UE (<NUM>, <NUM>); and
means for activating the command after transmitting the activation response, wherein the command is activated after a time period from the transmission of the second MAC-CE (<NUM>, <NUM>) including the activation response, and wherein the time period is based on a number of hops between the third UE (<NUM>, <NUM>) and the first UE (<NUM>, <NUM>) through which the activation request traveled, the number of hops being greater than or equal to one.