Patent Description:
NR is a set of enhancements to the long term evolution (LTE) mobile standard promulgated by 3GPP.

<NPL>, discusses aspects related to sidelink physical layer structure design. This document discloses single-layer transmission of the second stage SCI over the PSSCH. When the PSCCH transmissions use two layers, the second stage SCI occupies one of them, with or without multiplexed data over the same time-frequency resources.

<NPL>et al, discusses NR V2X physical layer structures. According to this document, in case of spatial multiplexing with two layers, single layer transmission of the 2nd-stage SCI is said to be more appropriate for transmission reliability.

<NPL>, describes a view on physical layer structure for sidelink in NR V2X. This document discloses mapping of the SCI-<NUM> to all layers of the PSSCH. However, the number of available modulated symbols is calculated per layer, indicating that rate matching of the polar encoded bits is not performed with respect to single-layer, but assuming multi-layer transmission.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for mapping two-stage sidelink control with a multiple-layer sidelink data channel. As will be described, the techniques presented herein allow mapping of the second stage of a two-stage sidelink control information (SCI) that is demodulated using demodulation reference signals (DMRS) of a multiple-layer sidelink data channel, even when the SCI and PSSCH have a different number of layers.

The following description provides examples of mapping two-stage sidelink control with multi-layer sidelink data channel that may be used for sidelink in communication systems, and is not limiting of the scope, applicability, or examples set forth in the claims. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein.

The techniques described herein may be used for various wireless networks and radio technologies me. For clarity, while aspects may be described herein using terminology commonly associated with <NUM>, <NUM>, and/or new radio (e.g., <NUM> NR) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR access may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., <NUM> or beyond), millimeter wave (mmW) targeting high carrier frequency (e.g., <NUM> or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC).

NR may also support beamforming and beam direction may be dynamically configured. Multiple-input multiple-output (MIMO) transmissions with precoding may also be supported.

As shown in <FIG>, the wireless communication network <NUM> may be in communication with a core network <NUM>. The core network <NUM> may in communication with one or more base station (BSs) <NUM> and/or user equipment (UE) <NUM> in the wireless communication network <NUM> via one or more interfaces.

According to certain aspects, the UEs <NUM> may be configured for sidelink communications. As shown in <FIG>, the UE 110a includes a SCI manager 122a and the UE 120b includes a SCI manager 122b. The SCI manager 122a and/or the SCI manager 122b may be configured to map, transmit, receive, demap, and/or demodulate a two-stage SCI with a multi-layer sidelink data channel, in accordance with aspects of the present disclosure. As discussed in more detail below, the SCI manager 122a and/or the SCI manager 122b may rate-match the second stage of two-stage SCI to as a single layer and map the second stage of the two-stage SCI to multiple antenna ports.

<FIG> illustrates example components of BS 110a and UE 120a (e.g., in the wireless communication network <NUM> of <FIG>, which may be similar components in the UE 120b), which may be used to implement aspects of the present disclosure.

At the BS 110a, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. For example, a BS may transmit a MAC CE to a UE to put the UE into a discontinuous reception (DRX) mode to reduce the UE's power consumption. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel. A MAC-CE may also be used to communicate information that facilitates communication, such as information regarding buffer status and available power headroom.

The processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor <NUM> may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and channel state information reference signal (CSI-RS). 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-232t. Downlink signals from modulators 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE 120a, the antennas 252a-252r may receive the downlink signals from the BS 110a, or sidelink signals from the UE 120b, and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. A MIMO detector <NUM> may obtain received symbols from all the demodulators in transceivers 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor <NUM> may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120a to a data sink <NUM>, and provide decoded control information to a controller/processor <NUM>.

On the uplink or sidelink, at UE 120a, a transmit processor <NUM> may receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from a data source <NUM> and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor <NUM>. The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the modulators in transceivers 254a-254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signals from the UE 120a may be received by the antennas <NUM>, processed by the demodulators in transceivers 232a-232t, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE 120a.

Antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE 120a and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM> may be used to perform the various techniques and methods described herein. The controller/processor <NUM> and/or other processors and modules at the UE 120a may perform or direct the execution of processes for the techniques described herein. For example, as shown in <FIG>, the controller/processor <NUM> of the UE 120a has a SCI manager <NUM> that may be configured map, transmit, receive, demap, and/or demodulate a two-stage SCI with a multi-layer sidelink data channel, in accordance with aspects of the present disclosure. As discussed in more detail below, the SCI manager <NUM> may rate-match the second stage of two-stage SCI to as a single layer and map the second stage of the two-stage SCI to multiple antenna ports. Although shown at the controller/processor, other components of the UE 120a may be used to perform the operations described herein.

Each subframe may include a variable number of slots (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>,. slots) depending on the SCS. Each slot may include a variable number of symbol periods (e.g., <NUM> or <NUM> symbols) depending on the SCS.

In NR, a synchronization signal block (SSB) is transmitted. In certain aspects, SSBs may be transmitted in a burst where each SSB in the burst corresponds to a different beam direction for UE-side beam management (e.g., including beam selection and/or beam refinement). The SSB includes a PSS, a SSS, and a two symbol PBCH. The SSB can be transmitted in a fixed slot location, such as the symbols <NUM>-<NUM> as shown in <FIG>. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SSBs may be organized into SS bursts to support beam sweeping. The SSB can be transmitted up to sixty-four times, for example, with up to sixty-four different beam directions for mmWave. The multiple transmissions of the SSB are referred to as a SS burst set. SSBs in an SS burst set may be transmitted in the same frequency region, while SSBs in different SS bursts sets can be transmitted at different frequency regions.

A scheduling entity (e.g., a BS <NUM>) allocates resources for communication among some or all devices and equipment within its service area or cell. BSs <NUM> are not the only entities that may function as a scheduling entity. In some examples, a UE <NUM> may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs <NUM>), and the other UEs <NUM> may utilize the resources scheduled by the UE <NUM> for wireless communication. In some examples, a UE <NUM> may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs <NUM> may communicate directly with one another in addition to communicating with a scheduling entity.

In some examples, the communication between the UEs <NUM> and BSs <NUM> is referred to as the access link. The access link may be provided via a Uu interface. Communication between devices may be referred as the sidelink.

In some examples, two or more subordinate entities (e.g., UEs <NUM>) may communicate with each other using sidelink signals. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (e.g., UE 120a) to another subordinate entity (e.g., another UE <NUM>) without relaying that communication through the scheduling entity (e.g., UE <NUM> or BS <NUM>), even though the scheduling entity may be utilized for scheduling and/or control purposes. One example of sidelink communication is PC5, for example, as used in V2V, LTE, and/or NR.

Various sidelink channels may be used for sidelink communications, including a physical sidelink discovery channel (PSDCH), a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), and a physical sidelink feedback channel (PSFCH). The PSDCH may carry discovery expressions that enable proximal devices to discover each other. The PSCCH may carry control signaling such as sidelink resource configurations and other parameters used for data transmissions, and the PSSCH may carry the data transmissions. The PSFCH may carry feedback such as CSI related to a sidelink channel quality.

<FIG> and <FIG> show diagrammatic representations of example V2X systems, in accordance with some aspects of the present disclosure. For example, the vehicles shown in <FIG> and <FIG> may communicate via sidelink channels and may perform sidelink CSI reporting as described herein.

The V2X systems, provided in <FIG> and <FIG> provide two complementary transmission modes. A first transmission mode, shown by way of example in <FIG>, involves direct communications (for example, also referred to as side link communications) between participants in proximity to one another in a local area. A second transmission mode, shown by way of example in <FIG>, involves network communications through a network, which may be implemented over a Uu interface (for example, a wireless communication interface between a radio access network (RAN) and a UE).

Referring to <FIG>, a V2X system <NUM> (for example, including vehicle to vehicle (V2V) communications) is illustrated with two vehicles <NUM>, <NUM>. The first transmission mode allows for direct communication between different participants in a given geographic location. As illustrated, a vehicle can have a wireless communication link <NUM> with an individual (V2P) (for example, via a UE) through a PC5 interface. Communications between the vehicles <NUM> and <NUM> may also occur through a PC5 interface <NUM>. In a like manner, communication may occur from a vehicle <NUM> to other highway components (for example, highway component <NUM>), such as a traffic signal or sign (V2I) through a PC5 interface <NUM>. With respect to each communication link illustrated in <FIG>, two-way communication may take place between elements, therefore each element may be a transmitter and a receiver of information. The V2X system <NUM> may be a self-managed system implemented without assistance from a network entity. A self-managed system may enable improved spectral efficiency, reduced cost, and increased reliability as network service interruptions do not occur during handover operations for moving vehicles. The V2X system may be configured to operate in a licensed or unlicensed spectrum, thus any vehicle with an equipped system may access a common frequency and share information. Such harmonized/common spectrum operations allow for safe and reliable operation.

<FIG> shows a V2X system <NUM> for communication between a vehicle <NUM> and a vehicle <NUM> through a network entity <NUM>. These network communications may occur through discrete nodes, such as a BS (e.g., the BS 110a), that sends and receives information to and from (for example, relays information between) vehicles <NUM>, <NUM>. The network communications through vehicle to network (V2N) links <NUM> and <NUM> may be used, for example, for long range communications between vehicles, such as for communicating the presence of a car accident a distance ahead along a road or highway. Other types of communications may be sent by the node to vehicles, such as traffic flow conditions, road hazard warnings, environmental/weather reports, and service station availability, among other examples. Such data can be obtained from cloud-based sharing services.

Roadside units (RSUs) may be utilized. An RSU may be used for V2I communications. In some examples, an RSU may act as a forwarding node to extend coverage for a UE. In some examples, an RSU may be co-located with a BS or may be standalone. RSUs can have different classifications. For example, RSUs can be classified into UE-type RSUs and Micro NodeB-type RSUs. Micro NB-type RSUs have similar functionality as the Macro eNB/gNB. The Micro NB-type RSUs can utilize the Uu interface. UE-type RSUs can be used for meeting tight quality-of-service (QoS) requirements by minimizing collisions and improving reliability. UE-type RSUs may use centralized resource allocation mechanisms to allow for efficient resource utilization. Critical information (e.g., such as traffic conditions, weather conditions, congestion statistics, sensor data, etc.) can be broadcast to UEs in the coverage area. Relays can rebroadcasts critical information received from some UEs. UE-type RSUs may be a reliable synchronization source.

As mentioned above, aspects of the present disclosure relate to techniques for mapping two-stage sidelink control information (SCI) with multi-layer sidelink data channel.

In certain systems, such as NR systems (e.g., Release <NUM> NR), a two-stage SCI is transmitted between user equipment (UEs) in sidelink communications. The two-stage SCI may include a first stage (referred to as SCI-<NUM>) and a second stage (referred to as SCI-<NUM>).

The SCI-<NUM> may include information regarding resource availability, such as resource reservation and resource allocation information, and information for decoding the SCI-<NUM>. The SCI-<NUM> may include at least information for decoding data and information for determining the intended recipient of the transmission.

<FIG> is a diagram illustrating example sidelink data channel, demodulation reference signal (DMRS) for the data channel, and two-stage SCI transmission in a slot <NUM>, in accordance with certain aspects of the present disclosure. In some example, the SCI-<NUM> is transmitted over the physical sidelink control channel (PSCCH), as shown in <FIG>. In some examples, the SCI-<NUM> may be transmitted over a second PSCCH, as shown in <FIG>. In some examples, the SCI-<NUM> may be transmitted (e.g., piggybacked) on the PSSCH (not shown).

According to certain aspects, the DMRS for the sidelink data channel (e.g., the PSSCH) is used to demodulate the SCI-<NUM>. For example, the PSSCH DMRS can be used to perform channel estimation for the SCI-<NUM>.

In some examples, the PSCCH may use <NUM> layer; however, the PSSCH can be more than <NUM> layer. Thus, the data sidelink channel may use multiple layers and the SCI-<NUM> may be transmitted using only a single port of the multi-layer PSSCH. When the SCI-<NUM> is sent with multi-layer PSSCH, there may be a power imbalance.

Accordingly, techniques and apparatus are desirable for mapping the second stage of the two-part SCI (e.g., the SCI-<NUM>) with a multiple-layer sidelink data channel, for example, even when the second stage of the two-part SCI and the data sidelink channel use different numbers of layers.

As discussed above (e.g., with respect to <FIG>), sidelink data channel demodulation reference signals (DMRS) can be used for channel estimation for a two-stage sidelink control. For example, the second stage (SCI-<NUM>) of the two-stage sidelink control information can be demodulated based on channel estimation using the physical sidelink shared channel (PSSCH) DMRS.

In some systems, a transmitting device, such as a sidelink user equipment (UE), generates bits (e.g., a sequence of information bits) for the SCI-<NUM>. The UE may then encode the bits (e.g., using polar code). The encoded bits are then rate-matched. After the rate-matching, the coded bits may be scrambled and modulated to produce the modulation symbols. The modulation symbols are then mapped to layers and then mapped to antenna ports. Precoding may be applied.

According to certain aspects, the UE rate-matches the SCI-<NUM> as if it were a single layer, even though the PSSCH can be multiple layers. In some examples, the rate-matching involves bit selection and bit interleaving. In some examples, the rate-matching includes determining the number of coded modulation symbols to map to an antenna port. In an illustrative example, there may be <NUM> tones and <NUM> layers PSSCH. In this case, for rate-matching as <NUM> layers, the UE may assume <NUM> coded modulation symbols. According to aspects herein, however, the UE may rate-match the SCI-<NUM> as a single layer. Thus, in the illustrative example, the UE may assume <NUM> code modulation symbols (e.g., the number of modulation symbols is assumed during the encoding). The rate-matched SCI-<NUM> is then mapped to an antenna port.

According to certain aspects, when the PSSCH is more than one layer, the other layers of the SCI-<NUM> are repetitions of the SCI-<NUM> on a first layer. The SCI-<NUM> duplicate layers are then mapped to the antenna ports. In some examples, precoder cycling may be applied. For example, different precoders may be used on different precoding resource block groups (PRGs). In some examples, the precoder cycling may be cyclic delay diversity (CDD) precoder cycling, where different precoders are applied on different tones.

The sequence of precoders and the precoder resource bundle size (e.g., the PRGs) may be known to both the transmitter and the receiver devices. For example, the sequence of precoders and/or precoder resource bundle size may be defined in a wireless specification, preconfigured (e.g., a preloaded configuration), configured (e.g., via a radio resource control (RRC) parameter), or indicated in the SCI-<NUM> (e.g., via an index value).

According to certain aspects, when the PSSCH is more than one layer, the UE applies CDD (e.g., mandatory CDD when more than one layer is used for the SCI-<NUM>). Thus, the output on one antenna port is a cyclically time-shifted version of the output on the other antenna ports. In some examples, the CDD may be achieved by precoder cycling on a per-tone basis. In some examples, the SCI-<NUM> rate-matching is repeated on the multiple layers, and the precoders are selected to apply the CDD to the layers.

According to certain aspects, the rate-matching as a single layer, duplicating layers, and/or CCD precoding is applied when a condition is satisfied (e.g., based on the UE determining the condition is satisfied). In some example, the condition is when the PSSCH is more than one layer. In some examples, the condition is when the SCI-<NUM> is frequency division multiplexed (FDD) with data. In some examples, the condition is when the SCI-<NUM> is FDMed with the SCI-<NUM>. In some examples, the condition is a combination of the above conditions.

According to certain aspects, the receiving device, such as a second sidelink UE, receives the SCI-<NUM>, decodes the SCI-<NUM>, and de-rate matches the SCI-<NUM>. In some cases, the second UE may choose to receive the SCI-<NUM> on only one of the antenna ports. For example, based on a capability of the second UE.

According to certain aspects, when a second-stage control layer is a repetition of another, the modulation symbols in that layer may be permuted relative to the other layers. Permuting the modulation symbols may advantageously provide frequency diversity for the sidelink control transmission.

In some examples, the permutation may be a reversal of the modulation-symbol order. For example, the modulation symbols for a second, repeated, layer may be in reverse order of the modulation symbols mapped to the first layer.

In some examples, the permutation may be configured, or preconfigured. In some examples, the permutation may be indicated in the first stage of the sidelink control (e.g., SCI-<NUM>). For example, a set of different permutations may be configured, and the indication of the permutation may be an index value of one of the configured permutations in the set.

In some examples, whether or not to permute the modulation symbols for the layers may be configured or preconfigured. In some examples, an indication of whether the modulation symbols are permutated may be indicated in the first stage of the sidelink control (e.g., SCI-<NUM>). In some examples, toggling the permuting may allow the UE to reduce complexity at times and to increase frequency diversity at other times.

According to certain aspects, although the modulation symbols on the different layers may be permuted, the content (e.g., the information and coded bits) on each layer is the same. In some examples, the same modulation symbols are used for the different layers.

<FIG> is a flow diagram illustrating example operations <NUM> for wireless communication, in accordance with certain aspects of the present disclosure. The operations <NUM> may be performed, for example, by a sidelink UE (e.g., such as a UE 120a in the wireless communication network <NUM>). Operations <NUM> may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor <NUM> of <FIG>). Further, the transmission and reception of signals by the UE in operations <NUM> may be enabled, for example, by one or more antennas (e.g., antennas <NUM> of <FIG>). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor <NUM>) obtaining and/or outputting signals.

Operations <NUM> may begin, at <NUM>, by rate-matching a multiple-layer second stage of a two-stage SCI transmission as a single layer. In some examples, the rate-matching includes determining a number of coded modulation symbols for second stage of the two-stage SCI based on a single layer.

According to certain aspects, the first UE maps the number of coded modulation symbols to an antenna port. In some examples, the first UE duplicates (e.g., repeats) the mapping of the number of coded modulation symbols on the multiple layers. In some examples, the first UE applies different precoders for different PRGs (e.g., precoder cycling). In some examples, the precoders and PRGs are specified at the first UE, configured, or indicated. For example, the first UE can indicate the precoders and PRGs to the second UE in a first stage of the two-stage SCI.

According to certain aspects, optionally at <NUM>, the first UE applies CDD to the second stage of the two-stage SCI (e.g., mandatory CDD when a condition is met). For example, the first UE can apply precoder cycling per-tone. In this case, the second stage is transmitted with a cyclic time-shift at the output of the multiple antenna ports.

At <NUM>, the first UE transmits the multiple-layer second stage of the two-stage SCI, to a second UE, using multiple antenna ports.

According to certain aspects, the first UE determines whether a condition is satisfied and performs the SCI-<NUM> rate-matching as a single layer based on the determination. In some examples, the first UE determines a PSSCH has more than one layer. In some examples, the first UE determines the second stage of the two-stage SCI is FDMed with data. In some examples, the first UE determines the second stage of the two-stage SCI is FDMed with a first stage of the two-stage SCI. In some examples, the first UE determines a combination of the conditions are met. The first UE rate-matches the multiple-layer second stage of the two-stage SCI transmission as a single layer based on the determination. In some examples, the first UE duplicates the rate-matched SCI-<NUM> on the multiple layers and/or applies CDD precoding to the layers when one or more of the conditions are met.

According to certain aspects, the two-stage SCI is transmitted with a PSSCH transmission. A first stage of the two-stage SCI may be transmitted on a first PSCCH and may carry resource availability information. The second stage of the two-stage SCI may be transmitted on a second PSCCH or on the PSSCH and may carry information to decode a data transmission.

The communications device <NUM> includes a processing system <NUM> coupled to a transceiver <NUM> (e.g., a transmitter and/or a receiver).

The processing system <NUM> includes a processor <NUM> coupled to a computer-readable medium/memory <NUM> via a bus <NUM>. In certain aspects, the computer-readable medium/memory <NUM> is configured to store instructions (e.g., computer-executable code) that when executed by the processor <NUM>, cause the processor <NUM> to perform the operations illustrated in <FIG>, or other operations for performing the various techniques discussed herein for mapping two-stage sidelink control with multi-layer sidelink data channel. In certain aspects, computer-readable medium/memory <NUM> stores code <NUM> for rate-matching a multiple-layer second stage of a two-stage SCI transmission as a single layer; code <NUM> for applying CDD to the second stage of the two-stage SCI; and/or code <NUM> for transmitting the multiple-layer second stage of the two-stage SCI, to a second UE, using multiple antenna ports, in accordance with aspects of the present disclosure. In certain aspects, the processor <NUM> has circuitry configured to implement the code stored in the computer-readable medium/memory <NUM>. The processor <NUM> includes circuitry <NUM> for rate-matching a multiple-layer second stage of a two-stage SCI transmission as a single layer; circuitry <NUM> for applying cyclic delay diversity (CDD) to the second stage of the two-stage SCI; and/or circuitry <NUM> for transmitting the multiple-layer second stage of the two-stage SCI, to a second UE, using multiple antenna ports, in accordance with aspects of the present disclosure.

Claim 1:
A method (<NUM>) for wireless communications by a first user equipment, UE, comprising:
rate-matching (<NUM>) a multiple-layer second stage of a two-stage sidelink control information, SCI, as a single layer, characterised in that:
the rate-matching comprises determining a number of coded modulation symbols for the multiple-layer second stage of the two-stage SCI based on a single layer; and
transmitting (<NUM>) the multiple-layer second stage of the two-stage SCI, to a second UE, using multiple antenna ports, wherein the number of coded modulation symbols is mapped to each of the multiple antenna ports.