Patent Description:
Document <CIT> relates to a method for intra-cluster D2D retransmission comprising: calculating parameters of a first and a second retransmission modes for an acknowledgement device in a cluster at which data from a network node is decoded correctly; reporting the parameters to the network node; and determining whether or not to retransmit the data to at least one non-acknowledgement device in the cluster at which the data from the network node is decoded incorrectly, in response to a selection be-tween the first and the second retransmission modes from the network node based at least in part on the parameters according to a pre-determined criterion.

Document <CIT> relates to a method including, obtaining, by a first mobile device, a data packet and determining, from a first set of resources, control resources for transmitting scheduling information associated with the data packet. The control resources include a physical sidelink control channel (PSCCH). The method includes determining, by the first mobile device from a second set of resources, acknowledgement (ACK)/negative acknowledgement (NACK) resources associated with the data packet and related to the control resources. The scheduling information includes transmission information for transmitting the data packet and an indication of the ACK/NACK resources. The method includes transmitting, by the first mobile device to a second mobile device, the scheduling information on the control resources and the data packet on a set of resources indicated by the transmission information and listening, by the first mobile device, for an ACK/NACK transmitted by the second mobile device on the ACK/NACK resources.

<NPL> relates to a discussion on HARQ support for NR sidelink. According to this document, for mode-<NUM> and mode-<NUM> coexistence scenario, the HARQ process ID associated with the model resource may be in conflict with the HARQ process ID associated with the mode2 resource, due to the fact that the HARQ process ID associated with the model resource may be allocated by the network and the HARQ process ID associated with the mode2 resource may be selected by the Tx UE itself.

The claimed invention is defined by the independent claims. Further embodiments of the claimed invention are described in the dependent claims.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for using a sidelink to assist in retransmission of data (sidelink-assisted retransmissions).

For example, UEs <NUM> of <FIG> may be configured to perform operations for sidelink assisted retransmissions described below with reference to <FIG>. Similarly, BSs <NUM> of <FIG> may be configured to perform operations described below with reference to <FIG> (e.g., to trigger a UE performing operations <NUM> to assist with sidelink retransmissions).

The wireless communication network <NUM> may be, for example, a New Radio (NR) or <NUM> network. BSs <NUM> may be involved in a multiple transmission reception point (multi-TRP) transmission to a UE <NUM>, in accordance with operations described below with reference to <FIG>, <NUM>, and <NUM> below.

As illustrated in <FIG>, the wireless communication network <NUM> may include a number of base stations (BSs) <NUM> and other network entities. A BS may be a station that communicates with user equipments (UEs). Each BS <NUM> may provide communication coverage for a particular geographic area. In NR systems, the term "cell" and next generation NodeB (gNB or gNodeB), NR BS, <NUM> NB, access point (AP), or transmission reception point (TRP) may be interchangeable. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network <NUM> through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

<FIG> illustrates example components of BS <NUM> and UE <NUM> (as depicted in <FIG>), which may be used to implement aspects of the present disclosure. For example, antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> may be configured to perform operations <NUM> of <FIG> and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be configured to perform operations <NUM> of <FIG>.

A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a through 232t. Downlink signals from modulators 232a through 232t may be transmitted via the antennas 234a through 234t, respectively.

At the UE <NUM>, the antennas 252a through 252r may receive the downlink signals from the base station <NUM> and may provide received signals to the demodulators (DEMODs) in transceivers 254a through 254r, respectively. A MIMO detector <NUM> may obtain received symbols from all the demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.

The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the demodulators in transceivers 254a through 254r (e.g., for SC-FDM, etc.), and transmitted to the base station <NUM>.

The controllers/processors <NUM> and <NUM> may direct the operation at the BS <NUM> and the UE <NUM>, respectively.

In either case, a pilot signal transmitted by the UE may be received by one or more network access devices, such as an, or a DU, or portions thereof.

NR networks may provide for sidelink transmissions between a transmitter user equipment (UE) and a receiver UE. In some cases, a UE can be configured with multiple transmit resource pools and multiple receive resource pools. When data is to be sent using a resource pool, the actual transmission resources may be selected dynamically from within the pool using one of various modes.

Within a PSCCH period there are separate subframe pools and resource block pools for control (physical sidelink control channel or PSCCH) and data (physical sidelink shared channel or PSSCH). Typically, PSCCH subframes precede subframes for PSSCH transmissions, similar to how in conventional (direct link) the control region precedes the data part of a subframe. The PSCCH carries sidelink control information (SCI) messages, which describe the dynamic transmission properties of the PSSCH that follow it. The receiving UE searches all configured PSCCH resource pools for SCI transmissions of interest to it. A UE can be a member of more than one sidelink communications group.

Among various use cases for sidelink communications is Industrial Internet of Things (IoT), for example, where UEs may communicate measurement and control data. Features of sidelink communications that might benefit Industrial IoT applications include reduced latency, multi-path diversity, coverage extension, battery-lifetime improvement, location enhancement, and Infrastructure-less communication.

<FIG> illustrates a first scenario suitable for IoT, where a serving base station (e.g., gNB) may allocate resources for sidelink communications. The example of <FIG> assumes the gNB has allocated sidelink resources, at least for a transmission from a transmitter UE (S2) to a receiver UE (S1). In another mode, a transmitting UE itself may select the resources according to certain rules (e.g., designed to reduce collisions). <FIG> illustrates a second scenario, where another device, such as a PLC (programmable logic controller) communicates with the UEs. In such a scenario, control signals may come from the gNB (as in the scenario shown in <FIG>) or from the PLC.

In scenarios shown in <FIG>, initial transmissions (e.g., control signals) to the UEs occur via a direct link from the gNB (<FIG>) or may occur via a direct link from the PLC or gNB (<FIG>). In some cases, however, these initial transmissions may not be successful, for example, due to blockage or poor channel conditions.

In such cases, aspects of the present disclosure propose using sidelink communications between UEs to assist in re-transmission. As will be described in greater detail below, a UE or group of UEs may be enlisted to re-transmit data in the case an initial transmission from a gNB or sidelink is not successful.

<FIG> illustrates example operations <NUM> for wireless communications by a user equipment (UE), in accordance with certain aspects of the present disclosure. The operations <NUM> may be performed, for example, by a first UE (e.g., such as a UE <NUM> in the wireless communication network <NUM>) assisting a gNB or PLC in re-transmissions to another UE via a sidelink.

Operations <NUM> begin at <NUM>, by obtaining first data intended for a second UE by decoding a first transmission of the first data targeting the second UE. At <NUM>, the first UE receives signaling indicating the first UE is to retransmit the first data to the second UE. At <NUM>, the first UE retransmits the first data to the second UE, via a sidelink, in response to the signaling.

<FIG> illustrates example operations <NUM> for wireless communications by a network entity, in accordance with certain aspects of the present disclosure. The operations <NUM> may be performed, for example, by a gNB or PLC of <FIG> to retransmit data via a sidelink with the assistance of a first UE performing operations <NUM> of <FIG>.

Operations <NUM> begin at <NUM>, by sending first data intended for a second UE in a first transmission. At <NUM>, the network entity signals a first UE to retransmit the first data to the second UE via a sidelink, if the network entity fails to receive an acknowledgment that the second UE successfully received the first data in the first transmission.

<FIG> shows an example of sidelink assisted re-transmission for the scenario shown in <FIG>. As shown, an initial (direct link) transmission of data from the gNB to UE S1 may fail. After detecting the failure, for example after not receiving a positive acknowledgment (ACK) from UE S1, the gNB triggers UE S2 to re-transmit the data to UE S1 via the sidelink. <FIG> shows a similar example for the scenario shown in <FIG>. As shown, after the PLC detects the failure of in initial transmission to UE S1, the PLC triggers UE S2 to re-transmit the data to UE S1 via the sidelink.

Various steps may be performed to prepare a UE or set of UEs to assist in sidelink retransmissions. <FIG> illustrate examples of such steps, as well as how UEs may subsequently assist in retransmissions, for the scenario shown in <FIG> and <FIG>. Similar steps may be performed for the scenario shown in <FIG> and <FIG>, for example, with the PLC performing action performed by the gNB in <FIG> (e.g., sending initial data and triggering retransmission).

As illustrated in <FIG>, as an initial step (step <NUM>), the UEs may perform sidelink channel measurement (e.g., measuring sidelink RSRP using pilot signals) and report sidelink channel quality to the gNB. Based on the reported sidelink channel measurement, the gNB may determine UE groups for sidelink (step <NUM>). For example, sets of UEs that all report good sidelink channel quality between each other may be grouped together as sidelink retransmissions between these UEs may have the best chance of success.

In some cases, UEs that are candidates to assist in retransmitting data via a sidelink may first obtain the data by monitoring the initial (direct link) transmissions from the gNB. gNBs may confirm good candidates for assisting in re-transmissions based on acknowledgment feedback.

This is illustrated in <FIG>, where a gNB sends an initial transmission targeting UE S1 (step <NUM>). In this example, UE S1 fails to successfully receive the initial transmission (as indicated by the "X"). UE S2, on the other hand, successfully decodes the initial transmission and sends an ACK to gNB (at step <NUM>, effectively identifying itself as a potential assisting UE).

As illustrated in <FIG>, after receiving the ACK from UE S2 (and not receiving an ACK from UE S1), the gNB sends a trigger to UE S2 (at step <NUM>). After receiving the trigger, UE S2 retransmits the data to UE S1 via the sidelink (step <NUM>). The trigger signaling may take any suitable form, such as Downlink Control Information (DCI). In some cases, the trigger may be sent to each UE in a group containing the target of the initial transmission. In such cases, separate UE-specific triggers could be sent or a group-cast trigger could be sent.

In some cases, an assisting UE (e.g., UE S2 in the example described above) may also have its own data (e.g., transport block) to acknowledge. In such cases, the assisting UE may send its own separate (separately coded) ACK/NACK for its own TB. As an alternative, the assisting UE could send a single message with the ACK for the targeted UE (e.g., UE S1 in the example described above) TB and its own TB jointly coded.

In some cases, the same or separate HARQ processes may be used for the initial transmission and retransmission. For example, the initial transmission from the gNB/PLC may include a HARQ process ID in DCI (if via a direct link from the gNB) or SCI (if via sidelink from the PLC). In some cases, the retransmission from the assisting UE may include the same HARQ process ID in the SCI corresponding to the retransmitted TB.

In some cases, the assisting UE may also have sidelink traffic for the targeted UE, in addition to the retransmitted data from gNB/PLC to targeted UE. In such cases, the assisting UE may use some mechanism to differentiate these two HARQ process.

According to one option, the UE may add one bit in the SCI to indicate whether the HARQ process is for the assisting UE's own sidelink traffic or for retransmission of the gNB/PLC's traffic. According to another option, a subset of HARQ IDs may be reserved for retransmitted traffic. In other words, these HARQ IDs may be used only for retransmitted traffic.

Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components. For example, various operations shown in <FIG> may be performed by various processors shown in <FIG>, such as processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM>. Various operations shown in <FIG> may be performed by various processors shown in <FIG>, such as processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM>.

Means for receiving may include a receiver (such as one or more antennas or receive processors) illustrated in <FIG>. Means for transmitting, means for retransmitting, and/or means for sending may include a transmitter (such as one or more antennas or transmit processors) illustrated in <FIG>. Means for measuring, means for reporting, means for providing, means for distinguishing, means for selecting and means for including may include a processing system, which may include one or more processors, such as processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> shown in <FIG>.

In some cases, rather than actually transmitting a frame a device may have an interface to output a frame for transmission (a means for outputting). For example, a processor may output a frame, via a bus interface, to a radio frequency (RF) front end for transmission. Similarly, rather than actually receiving a frame, a device may have an interface to obtain a frame received from another device (a means for obtaining). For example, a processor may obtain (or receive) a frame, via a bus interface, from an RF front end for reception.

For example, instructions for performing the operations described herein and illustrated in <FIG> and/or <NUM>.

Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be used.

Claim 1:
A method for wireless communications by a first user equipment, UE, comprising:
obtaining (<NUM>) first data from a network entity intended for a second UE by decoding a first transmission of the first data intended for the second UE;
receiving (<NUM>) signaling indicating the first UE is to retransmit the first data to the second UE; and
in response to the signaling:
transmitting sidelink control information, SCI, scheduling a physical sidelink shared channel, PSSCH, transmission from the first UE to the second UE, wherein the SCI includes a hybrid automatic repeat request, HARQ, process identifier, ID, and wherein the SCI indicates the HARQ process ID is associated with a retransmission of data from the network entity; and
retransmitting (<NUM>) the first data to the second UE via the PSSCH.