WO2024073995A1

WO2024073995A1 - Methods and apparatuses for sidelink csi reporting over unlicensed spectra

Info

Publication number: WO2024073995A1
Application number: PCT/CN2023/075298
Authority: WO
Inventors: Xin Guo; Haipeng Lei; Zhennian SUN; Xiaodong Yu
Original assignee: Lenovo (Beijing) Limited
Priority date: 2023-02-09
Filing date: 2023-02-09
Publication date: 2024-04-11

Abstract

Embodiments of the present disclosure relate to methods and apparatuses for sidelink (SL) channel state information (CSI) reporting over unlicensed spectra. According to an embodiment of the present disclosure, a first user equipment (UE) can include: a transceiver; and a processor coupled to the transceiver and configured to: obtain configuration information for SL CSI reporting on a first set of resource block (RB) sets, wherein the configuration information indicates: SL CSI reporting type (s); and SL CSI report format (s), each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s); and transmit, via the transceiver, an SL CSI request and SL CSI reference signal (RS) on each RB set of a second set of RB sets individually to a second UE, wherein the second set of RB sets is a subset of the first set of RB sets.

Description

METHODS AND APPARATUSES FOR SIDELINK CSI REPORTING OVER UNLICENSED SPECTRA

TECHNICAL FIELD

Embodiments of the present application are related to wireless communication technologies, and more particularly, related to methods and apparatuses for sidelink (SL) channel state information (CSI) reporting over unlicensed spectra.

BACKGROUND

A sidelink is a long-term evolution (LTE) feature introduced in 3^rd generation partnership project (3GPP) Release 12, and enables a direct communication between proximal user equipments (UEs) , in which data does not need to go through a base station (BS) or a core network. A sidelink communication system has been introduced into 3GPP 5G wireless communication technology, in which a direct link between two UEs is called a sidelink.

In new radio (NR) , SL CSI framework is introduced to unicast communication. How to support SL CSI reporting over unlicensed spectra needs to be discussed.

SUMMARY OF THE APPLICATION

Embodiments of the present application at least provide a technical solution for SL CSI reporting over unlicensed spectra.

According to some embodiments of the present application, a first UE may include: a transceiver; and a processor coupled to the transceiver and configured to: obtain configuration information for SL CSI reporting on a first set of resource block (RB) sets, wherein the configuration information indicates: SL CSI reporting type (s) ; and SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) ; and transmit, via the transceiver, an SL CSI request and SL CSI reference signal (RS) on each RB set of a second set of RB sets individually to a second UE, wherein the second set of RB sets is a subset of the first set of RB sets.

In some embodiments of the present application, the SL CSI reporting type (s) includes at least one of: individual CSI reporting; or combined CSI reporting.

In some embodiments of the present application, the SL CSI report format (s) includes at least one of: an individual CSI report format associated with the individual CSI reporting; or one of the following CSI report formats associated with the combined CSI reporting: a fixed-length CSI report format; a dynamic-length CSI report format; or a differential dynamic-length CSI report format.

In some embodiments of the present application, the processor is further configured to: receive, via the transceiver and from the second UE, at least one SL CSI report on at least one RB set within the first set of RB sets; and determine CSI in the at least one SL CSI report based on the obtained configuration information.

In some embodiments of the present application, CSI in each SL CSI report is determined further based on an SL CSI reporting type indicator associated with the SL CSI report.

In some embodiments of the present application, an SL CSI report of the at least one SL CSI report is carried by one of the follows: medium access control (MAC) control element (CE) ; sidelink control information (SCI) ; or physical sidelink feedback channel (PSFCH) .

In some embodiments of the present application, the processor is further configured to: determine a latency bound for SL CSI reporting for each RB set of the first set of RB sets; and transmit, via the transceiver, the determined latency bound for SL CSI reporting for each RB set of the first set of RB sets to the second UE.

According to some embodiments of the present application, a second UE may include: a transceiver; and a processor coupled to the transceiver and configured to:receive, via the transceiver, an SL CSI request and SL CSI-RS on each RB set of a first set of RB sets individually from a first UE; determine CSI based on SL CSI-RS (s) received on at least one RB set of the first set of RB sets; and determine an SL CSI reporting type and an SL CSI report format associated with the SL CSI reporting type for reporting the CSI to the first UE.

In some embodiments of the present application, the SL CSI reporting type and the SL CSI report format are determined based on configuration information for SL CSI reporting on a second set of RB sets, wherein the configuration information indicates: SL CSI reporting type (s) ; and SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) ; wherein the first set of RB sets is a subset of the second set of RB sets.

In some embodiments of the present application, the SL CSI reporting type is determined further based on slot (s) on which the SL CSI request (s) is (are) received and latency bound (s) for SL CSI reporting, wherein each latency bound is associated with a respective RB set of the at least one RB set.

In some embodiments of the present application, the processor is further configured to transmit, via the transceiver, at least one SL CSI report on one or more RB sets within the second set of RB sets based on the determined SL CSI reporting type and the determined SL CSI report format.

In some embodiments of the present application, in the case that the determined SL CSI reporting type is individual CSI reporting, each SL CSI report of the at least one SL CSI report is transmitted within an RB set containing the SL CSI-RS to which the determined CSI in the SL CSI report relates; or in the case that the determined SL CSI reporting type is combined CSI reporting, the processor is configured to transmit an SL CSI report on an RB set within the second set of RB sets, wherein the SL CSI report carries CSI determined based on the CSI-RS (s) received on the at least one RB set within the first set of RB sets.

In some embodiments of the present application, an SL CSI report of the at least one SL CSI report is carried by one of the follows: MAC CE; SCI; or PSFCH.

In some embodiments of the present application, the processor is further configured to transmit, via the transceiver, an SL CSI reporting type indicator indicating the determined SL CSI reporting type to the first UE.

According to some embodiments of the present application, a BS may include: a transceiver; and a processor coupled to the transceiver and configured to: transmit, via the transceiver, configuration information for SL CSI reporting on a first set of RB sets, wherein the configuration information indicates: SL CSI reporting type (s) ; and SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) .

In some embodiments of the present application, the processor is configured to transmit, via the transceiver, the configuration information via at least one of: a master information block (MIB) message, a system information block (SIB) message, a radio resource control (RRC) signaling, a MAC CE, or downlink control information (DCI) .

According to some embodiments of the present application, a method performed by a first UE may include: obtaining configuration information for SL CSI reporting on a first set of RB sets, wherein the configuration information indicates: SL CSI reporting type (s) ; and SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) ; and transmitting an SL CSI request and SL CSI reference signal (RS) on each RB set of a second set of RB sets individually to a second UE, wherein the second set of RB sets is a subset of the first set of RB sets.

According to some embodiments of the present application, a method performed by a second UE may include: receiving an SL CSI request and SL CSI-RS on each RB set of a first set of RB sets individually from a first UE; determining CSI based on SL CSI-RS (s) received on at least one RB set of the first set of RB sets; and determining an SL CSI reporting type and an SL CSI report format associated with the SL CSI reporting type for reporting the CSI to the first UE.

According to some embodiments of the present application, a method performed by a BS may include: transmitting configuration information for SL CSI reporting on a first set of RB sets, wherein the configuration information indicates: SL CSI reporting type (s) ; and SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) .

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application and are not therefore to be considered limiting of its scope.

FIG. 1 is a schematic diagram illustrating an exemplary wireless communication system according to some embodiments of the present application;

FIG. 2 illustrates an exemplary individual CSI report format according to some embodiments of the present application;

FIG. 3 illustrates a flowchart of an exemplary method for SL CSI reporting over unlicensed spectra according to some embodiments of the present application;

FIG. 4 illustrates an exemplary method for determining an SL CSI reporting type according to some embodiments of the present application;

FIG. 5 illustrates an exemplary PSFCH resource configuration according to some embodiments of the present application; and

FIG. 6 illustrates a simplified block diagram of an exemplary apparatus for SL CSI reporting over unlicensed spectra according to some embodiments of the present application.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of preferred embodiments of the present application and is not intended to represent the only form in which the present application may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present application.

While operations are depicted in the drawings in a particular order, persons skilled in the art will readily recognize that such operations need not be performed in the particular order as shown or in a sequential order, or that all illustrated operations need be performed, to achieve desirable results; sometimes one or more operations can be skipped. Further, the drawings can schematically depict one or more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing can be advantageous.

Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architecture and new service scenarios, such as 3GPP LTE and LTE advanced, 3GPP 5G NR, 5G-Advanced, 6G, and so on. It is contemplated that along with developments of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and moreover, the terminologies recited in the present application may change, which should not affect the principle of the present application.

FIG. 1 illustrates an exemplary wireless communication system 100 in accordance with some embodiments of the present application.

As shown in FIG. 1, the wireless communication system 100 includes at least one UE 101 and at least one BS 102. In particular, the wireless communication system 100 includes two UEs 101 (e.g., UE 101a and UE 101b) and one BS 102 for illustrative purpose. Although a specific number of UEs 101 and BS 102 are depicted in FIG. 1, it is contemplated that any number of UEs 101 and BSs 102 may be included in the wireless communication system 100.

According to some embodiments of the present disclosure, the UE (s) 101 may include computing devices, such as desktop computers, laptop computers, personal digital assistants (PDAs) , tablet computers, smart televisions (e.g., televisions connected to the Internet) , set-top boxes, game consoles, security systems (including security cameras) , vehicle on-board computers, network devices (e.g., routers, switches, and modems) , or the like.

According to some other embodiments of the present disclosure, the UE (s) 101 may include a portable wireless communication device, a smart phone, a cellular telephone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiver, or any other device that is capable of sending and receiving communication signals on a wireless network.

According to some other embodiments of the present disclosure, the UE (s) 101 may include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like.

According to some embodiments of the present disclosure, the UE (s) 101 may include vehicle UEs (VUEs) and/or power-saving UEs (also referred to as power sensitive UEs) . The power-saving UEs may include vulnerable road users (VRUs) , public safety UEs (PS-UEs) , and/or commercial sidelink UEs (CS-UEs) that are sensitive to power consumption. In an embodiment of the present disclosure, a VRU may include a pedestrian UE (P-UE) , a cyclist UE, a wheelchair UE or other UEs which require power saving compared with a VUE.

Moreover, the UE (s) 101 may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terminology used in the art.

In a sidelink communication system, a transmission UE may also be named as a transmitting UE, a transmitter UE, a Tx UE, a sidelink Tx UE, a sidelink transmission UE, or the like. A reception UE may also be named as a receiving UE, a receiver UE, an Rx UE, a sidelink Rx UE, a sidelink reception UE, or the like.

According to some embodiments of FIG. 1, UE 101a functions as a Tx UE, and UE 101b functions as an Rx UE. UE 101a may exchange sidelink messages with UE 101b through a sidelink, for example, via PC5 interface as defined in 3GPP TS 23.303. UE 101a may transmit information or data to other UE (s) within the sidelink communication system, through sidelink unicast, sidelink groupcast, or sidelink broadcast. For instance, UE 101a may transmit data to UE 101b in a sidelink unicast session. UE 101a may transmit data to UE 101b and other UE (s) in a groupcast group (not shown in FIG. 1) by a sidelink groupcast transmission session. Also, UE 101a may transmit data to UE 101b and other UE (s) (not shown in FIG. 1) by a sidelink broadcast transmission session.

Alternatively, according to some other embodiments of FIG. 1, UE 101b functions as a Tx UE and transmits sidelink messages, and UE 101a functions as an Rx UE and receives the sidelink messages from UE 101b.

In some embodiments of the present disclosure, UE 101a may communicate with UE 101b over licensed spectrums, whereas in other embodiments, UE 101a may communicate with UE 101b over unlicensed spectrums.

Both UE 101a and UE 101b in the embodiments of FIG. 1 may transmit information to BS 102 and receive control information from BS 102, for example, via LTE or NR Uu interface. BS 102 may be distributed over a geographic region. In certain embodiments of the present disclosure, BS 102 may also be referred to as an access point, an access terminal, a base, a base unit, a macro cell, a Node-B, an evolved Node B (eNB) , a generalized Node B (gNB) , a Home Node-B, a relay node, or a device, or described using other terminology used in the art. BS 102 is generally a part of a radio access network that may include one or more controllers communicably coupled to BS 102.

The wireless communication system 100 may be compatible with any type of network that is capable of sending and receiving wireless communication signals. For example, the wireless communication system 100 is compatible with a wireless communication network, a cellular telephone network, a time division multiple access (TDMA) based network, a code division multiple access (CDMA) based network, an orthogonal frequency division multiple access (OFDMA) based network, an LTE network, a 3GPP-based network, a 3GPP 5G network, a satellite communications network, a high-altitude platform network, and/or other communications networks.

In some embodiments of the present disclosure, the wireless communication system 100 is compatible with the 5G NR of the 3GPP protocol, wherein BS (s) 102 transmit data using an orthogonal frequency division multiplexing (OFDM) modulation scheme on the downlink (DL) and UE (s) 101 transmit data on the uplink (UL) using a discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM) or cyclic prefix-OFDM (CP-OFDM) scheme. More generally, however, the wireless communication system 100 may implement some other open or proprietary communication protocols, for example, WiMAX, among other protocols.

In some embodiments of the present disclosure, BS (s) 102 may communicate using other communication protocols, such as the IEEE 802.11 family of wireless communication protocols. Further, in some embodiments of the present disclosure, BS (s) 102 may communicate over licensed spectrums, whereas in other embodiments, BS (s) 102 may communicate over unlicensed spectrums. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol. In yet some embodiments of the present disclosure, BS (s) 102 may communicate with UE (s) 101 using the 3GPP 5G protocols.

In NR, accommodating multiple uncoordinated UEs in an unlicensed spectrum requires channel access procedures defined for NR. Following a successful channel access procedure performed by a communicating node, the channel can be used by the communicating node during a period until the end of the period. Such a period may be referred to as a channel occupancy time (COT) . During a COT, one or more transmissions may be exchanged between the communicating nodes, wherein a transmission may be a downlink transmission or an uplink transmission.

Dynamic channel access procedures are usually used by a BS or a UE to access a channel in an unlicensed spectrum. Dynamic channel access procedures may be based on listen-before-talk (LBT) , where a transmitter listens to potential transmission activity on a channel prior to transmitting and applies a random back-off time in some cases. Two main types of dynamic channel access procedures may be defined in NR. One is Type-1 dynamic channel access procedure, which is also referred to as LBT type 1 or LBT cat4. The other is Type-2 dynamic channel access procedure, which is also referred to as LBT type 2.

Type-1 dynamic channel access procedure may be used to initiate data transmission at the beginning of a COT. The initiator for the Type-1 dynamic channel access procedure may be either a BS or a UE. The Type-1 dynamic channel access procedure may be summarized as follows.

First, the initiator listens and waits until a channel (e.g., a frequency channel) is available during at least one period referred to as a defer duration. The defer duration may consist of 16 μs and a number (e.g., "m_p" in the following Table 1 or Table 2, which will be illustrated below) of 9 μs slots. As shown in Table 1 and Table 2, a value of "m_p" depends on a value of CAPC (represented as "p" ) . Accordingly, the defer duration depends on the value of CAPC as shown in the following Table 1 or Table 2. A channel is declared to be available if the received energy during at least 4 μs of each 9 μs slot is below a threshold.

Once the channel has been declared available during the defer duration, the transmitter starts a random back-off procedure during which it will wait a random period of time.

The UE starts the random back-off procedure by initializing a back-off timer with a random number within a contention window (CW) . The random number is drawn from a uniform distribution [0, CW] and represents that the channel must be available for a timer duration (e.g., defined by the random number multiplying 9 μs) before transmission can take place. The value of "CW" may be selected from "allowed CW_p sizes" (the minimum value is represented as CW_min, p, and the maximum value is represented as CW_max, p) in the following Table 1 or Table 2, which depends on a value of CAPC.

The back-off timer is decreased by one for each sensing slot duration (e.g., 9 μs) the channel is sensed to be idle; whenever the channel is sensed to be busy, the back-off timer is put on hold until the channel has been idle for a defer duration.

Once the back-off timer has expired (e.g., the back-off timer is decreased to be 0) , the random back-off procedure is completed, and the transmitter has acquired the channel and can use it for transmission up to a maximum channel occupancy time (MCOT) (e.g., T_mcot, p in the following Table 1 or T_ulmcot, p in the following Table 2, which depends on a value of CAPC) .

The following Table 1 and Table 2 illustrate exemplary CAPC for DL and CAPC for UL, respectively, and corresponding values of m_p, CW_min, p, CW_max, p, T_mcot, p, T_ulmcot, p, and allowed CW_p sizes. Table 1 is the same as Table 4.1.1-1 in TS 37.213 and Table 2 is the same as Table 4.2.1-1 in TS 37.213. When a BS intends to initiate a channel occupancy for DL transmission, it may determine a CAPC value before performing a Type-1 channel access procedure, and then determine the corresponding values (e.g., m_p, CW_min, p, CW_max, p, T_mcot, p, and allowed CW_psizes) used in the Type-1 channel access procedure according to Table 1. When a UE intends to initiate a channel occupancy for UL transmission, it may determine a CAPC value before performing a Type-1 channel access procedure, and then determine the corresponding values (e.g., m_p, CW_min, p, CW_max, p, T_ulmcot, p, and allowed CW_psizes) used in the Type-1 channel access procedure according to Table 2.

Table 1: Channel Access Priority Class for DL

Table 2: Channel Access Priority Class for UL

The size of the contention window may be adjusted based on hybrid automatic repeat request (HARQ) reports received from the transmitter during a reference interval, which covers the beginning of the COT. For each received HARQ report, the contention window is (approximately) doubled up to the limit CW_max, p if a negative HARQ report (e.g., non-acknowledgement (NACK) ) is received. For a positive HARQ report (e.g., acknowledgement (ACK) ) , the contention window is reset to its minimum value, i.e., CW=CW_min, p.

Type-2 dynamic channel access procedure may be used for COT sharing and transmission of discovery bursts. Depending on a duration of a gap (also referred to as "COT sharing gap" ) in the COT, Type-2 dynamic channel access procedure may be further classified into the following three procedures, wherein which procedure to be used may be determined depending on the duration of the gap between two transmission bursts.

● Type 2A dynamic channel access procedure (also referred to as LBT cat2 or LBT type 2A) : which is used when the gap is 25 μs or more for transmission of the discovery bursts.

● Type 2B dynamic channel access procedure (also referred to as LBT type 2B) : which is used when the gap is 16 μs.

● Type 2C dynamic channel access procedure (also referred to as LBT type 2C) : which is used when the gap is 16 μs or less after the preceding transmission burst.

For Type 2C dynamic channel access procedure, no idle sensing is required between the transmission bursts. In such scenario, the duration of a transmission burst is limited to at most 584 μs. Such a short transmission burst may carry small amount of user data, uplink control information (UCI) such as HARQ status reports and CSI reports.

Type 2A dynamic channel access procedure and Type 2B dynamic channel access procedure may be similar to Type-1 dynamic channel access procedure but without the random back-off. That is, in Type 2A dynamic channel access procedure and Type 2B dynamic channel access procedure, if a channel is detected to be idle in the gap, it is declared to be available; if it is detected to be busy, the COT sharing has failed and the transmission cannot occur using COT sharing in this COT. If the COT sharing gap is 16 μs, Type 2B dynamic channel access procedure may be used and the channel must be detected to be idle in the 16 μs gap prior to the next transmission burst. If the COT sharing gap is 25 μs or longer, Type 2A dynamic channel access procedure may be used and the channel must be detected to be idle during at least 25 μs immediately preceding the next transmission burst.

The above embodiments provide several dynamic channel access procedures in an unlicensed spectrum for NR. These dynamic channel access procedures may also apply for sidelink transmissions in an unlicensed spectrum.

In NR Release 16, SL CSI framework is introduced to unicast communication where a Tx UE transmits SL CSI-RS to an Rx UE so that the Rx UE can measure CSI based on the SL CSI-RS and report it back to the Tx UE via a CSI report, which may be carried within a physical sidelink shared channel (PSSCH) . Based on the fed back CSI, the Tx UE may adjust its transmission.

SL CSI-RS may be transmitted in a PSSCH of a slot. The design of the SL CSI-RS may be based on the CSI-RS design of Release 15 NR Uu. In addition, the resource mapping of SL CSI-RS in a physical RB (PRB) may be based on the CSI-RS resource mapping patterns in NR Uu, which support up to two antenna ports (because in NR vehicle-to-everything (V2X) SL, up to two streams can be supported in a PSSCH) . Each PRB within the PSSCH uses the same pattern for the SL CSI-RS.

SL CSI-RS is not transmitted on symbols containing PSCCH, the 2^nd-stage SCI or PSSCH demodulation reference signal (DMRS) . The SL CSI-RS configuration includes a resource mapping pattern and the number of antenna ports for SL CSI-RS. The SL CSI-RS configuration may be selected by the Tx UE and provided to the Rx UE via PC5 radio resource control (RRC) signaling.

In some cases, the Tx UE may configure aperiodic CSI reporting from the Rx UE. In some cases, the Tx UE may transmit a one-bit CSI request in the 2^nd-stage SCI along with SL CSI-RS to the Rx UE of a unicast link, so as to trigger the Rx UE to feed back a CSI report. In response to receiving the SL CSI-RS, the Rx UE may measure CSI based on the SL CSI-RS transmitted by the Tx UE and feed back the CSI to the Tx UE. To avoid outdated CSI, the Rx UE is expected to feed back the CSI within a maximum amount of time. This maximum amount of time may be referred to as a latency bound, which may be determined by the Tx UE and provided to the Rx UE via PC5-RRC signaling. In some cases, the Rx UE may feed back the CSI to the Tx UE via a CSI report. For example, the CSI report may be carried in a MAC CE over a PSSCH sent from the Rx UE to the Tx UE. It is expected that the Rx UE feeds back the CSI report within the latency bound.

The CSI may include a channel quality indicator (CQI) and a rank indicator (RI) . As no pre-coding matrix indication (PMI) feedback is supported in NR V2X SL, open-loop multi-antenna SL transmissions, instead of closed-loop multi-antenna SL transmissions, may be performed by the Tx UE based on the CQI and RI fed back by the Rx UE.

CQI may be selected from a CQI table that is derived based on the configured modulation and coding scheme (MCS) table for a PSSCH. CQI provides an indication of the highest MCS that can be supported by the SL channel measured at the Rx UE. CQI may be used for such as link adaptation adjusting the MCS for a transmission.

Based on channel measurements of SL CSI-RSs sent from up to two antenna ports of the Tx UE, the Rx UE may determine the RI that corresponds to the rank of the measured SL channel. The rank of a channel may determine the number of streams that can be supported by the channel. As up to two streams can be supported for a PSSCH transmission in NR V2X SL, the RI may be equal to 1 or 2. RI may be used for such as rank adaptation adjusting the number of streams that can be sent in a PSSCH with a multi-antenna transmission.

In the aforementioned SL CSI framework, there is no information, such as CSI process identity (ID) , defined for the SL CSI framework. To avoid ambiguity, a new CSI reporting can be triggered only if the current CSI report is received, or the latency bound expires.

According to some embodiments of the present application, for unlicensed spectra, a frequency range (e.g., a bandwidth part (BWP) , a carrier, a resource pool, etc. ) may be divided into multiple channels upon which a channel access procedure is defined. Each channel may be referred to as an RB set. In some cases, operating on the carrier may require guard bands between RB sets. In some embodiments, the size of the guard bands may be chosen such that no filtering is needed to ensure that transmission on one RB set does not cause significant interference to a neighboring RB set not available for transmission.

For example, the concept of "RB set" is specified in Release 16 5G NR in unlicensed spectrum (NR-U) , which defines the exact available RBs without RBs in either inter-cell guard band or intra-cell guard band. The guard band and RB set are configured by RRC signaling in unit of common resource block (CRB) . In detail, when a UE is configured with intraCellGuardBand for a carrier, the UE is provided with N_RB-set-1 intra-cell guard bands on the carrier, each defined by a start CRB and an end CRB, i.e., andrespectively. The intra-cell guard bands separate N_RB-set RB sets, each defined by a start CRB and an end CRB, i.e., andrespectively. The UE determines and the remaining end and start CRBs as andWhen the UE is not configured with intraCellGuardBand, the UE determines intra-cell guard band and corresponding RB set according to the default intra-cell guard band pattern from TS38.101 corresponding to μ and carrier sizeThe specific definitions of the variables or parameters as mentioned above can be found in 3GPP standard documents.

In unlicensed spectra, SL CSI is also beneficial because it can help the Tx UE to determine the RB set for transmission and adjust transmission parameters. As stated above, in NR Release 16 SL CSI framework, a new CSI reporting can be triggered only if the current CSI report is received, or the latency bound expires. Therefore, it may result in inefficiency in CSI reporting and spectrum utilization to directly apply the NR Release 16 SL CSI framework in a multiple channel access scenario over unlicensed spectra, which is characterized by wide bandwidth and opportunistic channel access mechanism. To this end, an efficient solution for supporting SL CSI reporting in the multiple channel access scenario over unlicensed spectra is needed.

Embodiments of the present application provide solutions for SL CSI reporting over unlicensed spectra. For example, embodiments of the present application provide several solutions regarding configurations, signaling, UE behaviors, and procedures for supporting SL CSI reporting over unlicensed spectra, which can increase the efficiency in CSI reporting and spectrum utilization in the multiple channel access scenario over unlicensed spectra. More details will be described in the following text in combination with the appended drawings.

In some embodiments of the present application, to support the SL CSI reporting in the multiple channel access scenario over unlicensed spectra, a UE may obtain configuration information for SL CSI reporting on a first set of RB sets. The first set of RB sets may be included in a frequency range (e.g., a BWP, a carrier, a resource pool, etc. ) . In some cases, the UE may be a CSI triggering UE, which transmits SL CSI-RS. In some other cases, the UE may be a CSI reporting UE, which transmits SL CSI report (s) .

In some embodiments of the present application, the UE may obtain the configuration information for SL CSI reporting on the first set of RB sets based on configuration. Specifically, obtaining the configuration information based on configuration (i.e., the configuration information is configured to the UE) may refer to that: the configuration information is transmitted by a BS (e.g., BS 102 as shown in FIG. 1) to the UE via at least one of: a SIB message, a MIB message, an RRC signaling, a MAC CE, or DCI, such that the UE may receive the configuration information from the BS. In an embodiment of the present application, obtaining the configuration information based on configuration may apply to the scenario where the UE is in coverage of a network.

In some other embodiments of the present application, the UE may obtain the configuration information for SL CSI reporting on the first set of RB sets based on pre-configuration or pre-definition. Specifically, obtaining the configuration information based on pre-configuration or pre-definition (i.e., the configuration information is pre-configured or pre-defined to the UE) may refer to that: the configuration information may be hard-wired into the UE or stored on a subscriber identity module (SIM) or universal subscriber identity module (USIM) card for the UE, such that the UE may obtain the configuration information within the UE. In an embodiment of the present application, obtaining the configuration information based on pre-configuration or pre-definition may apply to the scenario where the UE is out of coverage of the network.

In some embodiments of the present application, the configuration information for SL CSI reporting on the first set of RB sets may indicate SL CSI reporting type (s) and SL CSI report format (s) , where each SL CSI report format is associated with a respective SL CSI reporting type of the SL CSI reporting type (s) indicated in the configuration information.

In an embodiment, based on the association between RB sets carrying SL CSI-RSs and RB sets carrying corresponding SL CSI reports, SL-CSI reporting may be classified into at least individual CSI reporting and combined CSI reporting. In individual CSI reporting, SL CSI-RSs may be transmitted in multiple RB sets and corresponding SL CSI reports are responded to individually in the multiple RB sets with each SL CSI report corresponding to an RB set of the multiple RB sets. In other words, an SL CSI report including CSI determined based on an SL CSI-RS is transmitted in an RB set where the SL CSI-RS is transmitted. That is to say, the transmissions of SL CSI-RS and corresponding CSI determined (or derived) based on the CSI-RS are to be confined within the same RB set. In combined CSI reporting, SL CSI-RSs may be transmitted in multiple RB sets and CSI determined based on the SL CSI-RSs is included in an SL SCI report transmitted within an RB set.

Accordingly, the SL CSI reporting type (s) indicated by the configuration information for SL CSI reporting on the first set of RB sets may include at least one of individual CSI reporting or combined CSI reporting.

In an embodiment, the SL CSI report format (s) indicated by the configuration information for SL CSI reporting on the first set of RB sets may include at least one of:

● an individual CSI report format associated with the individual CSI reporting; or

● one of the following CSI report formats associated with the combined CSI reporting: a fixed-length CSI report format; a dynamic-length CSI report format; or a differential dynamic-length CSI report format.

As an example, the configuration information may indicate individual CSI reporting and an individual CSI report format associated with the individual CSI reporting. As another example, the configuration information may indicate combined CSI reporting and a combined CSI report format (e.g., one of the aforementioned CSI report formats associated with the combined CSI reporting) . As yet another example, the configuration information may indicate both individual CSI reporting and combined CSI reporting, an individual CSI report format associated with the individual CSI reporting, and a combined CSI report format (e.g., one of the aforementioned CSI report formats associated with the combined CSI reporting) .

In some embodiments of the present application, the individual CSI report format associated with the individual CSI reporting may follow the CSI report format as defined in 3GPP Release 16 or 3GPP Release 17. The individual CSI reporting is different from the CSI reporting as defined in 3GPP Release 16 or 3GPP Release 17 in that SL CSI-RS and the corresponding SL CSI report are contained within the same RB set. Such design may solve the ambiguity problem of SL CSI reports due to SL CSI-RSs transmitted in multiple RB sets, without bringing additional signaling overhead. For example, in the multiple channel access scenario, for an SL CSI report, it is necessary to identify its corresponding SL CSI-RS from which CSI in the SL CSI report is determined. One solution to solve the ambiguity problem of SL CSI reports is to explicitly indicate a CSI process ID for an SL CSI report. However, such solution may result in additional signaling overhead. In the embodiments of the present application, SL CSI-RS and the corresponding SL CSI report can be associated by the frequency domain resource (e.g., within the same RB set) , which avoids introducing additional signaling overhead.

FIG. 2 illustrates an exemplary individual CSI report format according to some embodiments of the present application.

Referring to FIG. 2, the individual CSI report format may include eight bits (i.e., an octave (Oct) ) in total, which include five bits for indicating CSI (e.g., one bit for indicating RI and four bits for indicating CQI) , and three reserved bits (R) . It is contemplated that the individual CSI report format is not limited to the one illustrated in FIG. 2.

In some embodiments of the present application, a fixed-length CSI report format associated with the combined CSI reporting may include one or more fields, wherein each field may correspond to a respective RB set of the first set of RB sets and be used to carry SL CSI determined based on SL CSI-RS on the respective RB set. The number of fields included in the fixed-length CSI report format may be equal to the number of RB sets included in the first set of RB sets. In an embodiment, the fields in the fixed-length CSI report format may be arranged in ascending or descending order of corresponding indexes of RB sets.

In some examples, for SL CSI-RS in each RB set of the first set of RBs, the measured RI may be indicated by one bit and the measured CQI may be indicated by four bits. As a result, five bits are needed for SL CSI corresponding to an RB set. Accordingly, each field in the fixed-length CSI report format may include five bits. Assuming that the first set of RB sets includes four RB sets (e.g., a BWP is divided into four RB sets) , the fixed-length CSI report format may include twenty bits. It is contemplated that other designs for the fixed-length CSI report format do not depart from spirit and scope of the present application.

In such embodiments, if CSI is not determined (or derived) on an RB set, the field corresponding to the RB set may be padded with a default value, such as all zeros or all ones.

In some embodiments of the present application, a dynamic-length CSI report format associated with the combined CSI reporting may include extended CSI, wherein the extended CSI includes CSI and information (e.g., an index of an RB set) related to an RB set on which the CSI is determined (or derived) . If CSI is not determined on an RB set, then the dynamic-length CSI report format does not include extended CSI for the RB set.

For example, assuming that the first set of RB sets includes four RB sets (e.g., a BWP is divided into four RB sets) , an index of an RB set may be indicated by two bits. Moreover, for SL CSI-RS in each RB set of the first set of RB sets, the measured RI may be indicated by one bit and the measured CQI may be indicated by four bits. As a result, five bits are needed for SL CSI on an RB set. Given this, extended CSI for an RB set may include seven bits.

In such example, if SL CSI is determined only on one RB set of the four RB sets, then the SL CSI report with the dynamic-length CSI report format may include seven bits. If SL CSI is determined on all of the four RB sets, then the SL CSI report with the dynamic-length CSI report format may include twenty-eight bits. In an embodiment, the fields in the dynamic-length CSI report format may be arranged in ascending or descending order of corresponding indexes of RB sets. In another embodiment, the fields in the dynamic-length CSI report format may be arranged in ascending or descending order of corresponding values of the measured RI or CQI. In yet another embodiment, the fields in the dynamic-length CSI report format may be arranged in an arbitrary order. It is contemplated that other designs for the dynamic-length CSI report format do not depart from spirit and scope of the present application.

In some embodiments of the present application, a differential dynamic-length CSI report format associated with the combined CSI reporting may also include extended CSI, wherein the extended CSI includes CSI and information (e.g., an index of an RB set) related to an RB set on which the CSI is determined (or derived) . The differential dynamic-length CSI report format is different from the dynamic-length CSI report format in that a reference RB set may be determined. The reference RB set may be an RB set on which SL CSI is determined. For example, the reference RB set may be an RB set with a lowest index or highest index in a set of RB sets on which SL CSI is determined, or an RB set on which a maximum or minimum value of CQI is measured. For the reference RB set, the differential dynamic-length CSI report format may indicate CQI on the reference RB set; for other RB sets on which SL CSI is determined, the differential dynamic-length CSI report format may indicate differential CQI (e.g., an offset of CQI) relative to the CQI on the reference RB set.

For example, assuming that the first set of RB sets includes four RB sets (e.g., a BWP is divided into four RB sets) , the extended CSI for the reference RB set may include seven bits with two bits indicating the index of the reference RB set, one bit indicating RI on the reference RB set, and four bits indicating CQI on the reference RB set. The extended CSI for another RB set on which SL CSI is determined may include six bits with two bits indicating the index of the another RB set, one bit indicating RI on the another RB set, and three bits indicating an offset of CQI relative to the CQI on the reference RB set.

In such example, if SL CSI is determined only on one RB set of the four RB sets, then the SL CSI report with the differential dynamic-length CSI report format may include seven bits. If SL CSI is determined on all of the four RB sets, then the SL CSI report with the differential dynamic-length CSI report format may include twenty-five bits. In an embodiment, the fields in the differential dynamic-length CSI report format may be starting with the extended CSI for the reference RB set and followed by extended CSI for other reference RB set (s) . It is contemplated that other designs for the differential dynamic-length CSI report format do not depart from spirit and scope of the present application.

The differential dynamic-length CSI report format is feasible because RB sets located closely in the frequency domain may share similar channel characteristics.

In some embodiments of the present application, the configuration information for SL CSI reporting on the first set of RB sets may also include a condition for triggering the combined CSI reporting. The condition may define when a plurality of SL CSI reports, each of which corresponds to an SL CSI-RS confined within an RB set, can be fed back within a same slot. The condition may be used for a CSI reporting UE to determine an SL CSI reporting type, which will be described in detail later with reference to FIG. 3. In some embodiments of the present application, such a condition may be not explicitly indicated by the configuration information, but implicitly defined in UE behaviors.

FIG. 3 illustrates a flowchart of an exemplary method for SL CSI reporting over unlicensed spectra according to some embodiments of the present application.

The method in the example of FIG. 3 may be performed by a first UE (e.g., UE 101a in FIG. 1) and a second UE (e.g., UE 101b in FIG. 1) . The first UE may be a CSI triggering UE, which transmits SL CSI-RS (s) . The second UE may be a CSI reporting UE, which transmits SL CSI report (s) . Although the method is illustrated in a system level by two UEs, persons skilled in the art can understand that the operations implemented in the first UE and those implemented in the second UE can be separately implemented and incorporated by other apparatus with the like functions.

In some embodiments of FIG. 3, the first UE and the second UE may obtain the configuration information for CSI reporting on a first set of RB sets. All the definitions and designs regarding the configuration information for CSI reporting as described above may also apply here. For example, the first UE and the second UE may obtain the configuration information based on configuration, pre-configuration, or pre-definition.

In some embodiments of FIG. 3, the first UE may determine a latency bound for SL CSI reporting for each RB set of the first set of RB sets, and transmit the determined latency bound for SL CSI reporting for each RB set of the first set of RB sets to the second UE. For example, the latency bound may be transmitted by the first UE to the second UE via PC5-RRC signaling. Consequently, the second UE may receive a latency bound for SL CSI reporting for each RB set of the first set of RB sets from the first UE. In some examples, latency bound (s) may be determined per BWP, per carrier, per resource pool, per frequency range, or per UE.

Referring to FIG. 3, in operation 301, the first UE may transmit an SL CSI request and SL CSI-RS on each RB set of a second set of RB sets individually to the second UE. The second set of RB sets is a subset of the first set of RB sets. For example, the second set of RB sets may be determined based on the first UE's intention and/or channel access procedure (e.g., Type-1 dynamic channel access procedure) on the first set of RB sets. The SL CSI request and the SL CSI-RS may be transmitted on a same slot. For example, the SL CSI request may be transmitted in SCI (e.g., 2^nd-stage SCI) and the SL CSI-RS may be transmitted in PSSCH associated with the SCI. The SL CSI request may indicate the second UE to report CSI relative to the SL CSI-RS.

In operation 301, the second UE may receive an SL CSI request and SL CSI-RS on each RB set of a third set of RB sets individually from the first UE. The third set of RB sets is a subset of the second set of RB sets. In some cases, the SL CSI request and SL CSI-RS transmitted on some RB sets (other than the third set of RB sets) may not be successfully received by the second UE.

In operation 302, the second UE may determine (or derive) CSI based on the SL CSI-RS (s) received on at least one RB set of the third set of RB sets. In some cases, the second UE may fail to determine CSI based on SL CSI-RS (s) received on some RB sets within the third set of RB sets.

In some embodiments, it is not permitted to determine CSI based on SL CSI-RSs across RB sets. That is, the second UE determines CSI on an RB set based on only SL CSI-RS confined within the RB set.

In some embodiments, a COT may be initiated by one of the first UE and the second UE and shared to the other UE. The COT may be initiated by Type-1 dynamic channel access procedure. During the COT, one or more transmission bursts can be exchanged between the first UE and the second UE, where a transmission burst corresponds to one direction of a sidelink transmission. For example, in a transmission burst, the first UE may transmit SL CSI-RS to the second UE. In some embodiments, it is not permitted to determine CSI based on SL CSI-RS (s) across transmission bursts. That is, the second UE determines CSI based on only SL CSI-RS confined within a transmission burst.

The CSI reference resource in sidelink may be defined as follows:

● In the frequency domain, the CSI reference resource is defined by a group of SL PRBs containing the SL CSI-RS to which the derived CSI relates. In some embodiments, the group of SL PRBs are confined within an RB set.

● In the time domain, the CSI reference resource for CSI reporting in SL slot n is defined by an individual SL slot n_{CSI_ref} where n_{CSI_ref} is the same SL slot as the corresponding CSI request.

In operation 303, the second UE may determine an SL CSI reporting type and an SL CSI report format associated with the SL CSI reporting type for reporting the CSI determined in operation 302 to the first UE.

In some embodiments, the SL CSI reporting type and the SL CSI report format may be determined based on the obtained configuration information for SL CSI reporting on the first set of RB sets as described above.

In an embodiment, the obtained configuration information may indicate individual CSI reporting and an individual CSI report format associated with the individual CSI reporting. Then, in operation 303, the second UE may determine that the SL CSI reporting type for reporting the CSI is the individual CSI reporting and the SL CSI report format for reporting the CSI is the individual CSI report format.

In another embodiment, the obtained configuration information may indicate combined CSI reporting and a combined CSI report format, e.g., one of the following CSI report formats associated with the combined CSI reporting: a fixed-length CSI report format; a dynamic-length CSI report format; or a differential dynamic-length CSI report format. Then, in operation 303, the second UE may determine that the SL CSI reporting type for reporting the CSI is the combined CSI reporting and the SL CSI report format for reporting the CSI is the combined CSI report format.

In yet another embodiment, the obtained configuration information may indicate both individual CSI reporting and combined CSI reporting, an individual CSI report format associated with the individual CSI reporting, and a combined CSI report format, e.g., one of the following CSI report formats associated with the combined CSI reporting: a fixed-length CSI report format; a dynamic-length CSI report format; or a differential dynamic-length CSI report format.

In such embodiment, the second UE may determine the SL CSI reporting type for reporting the CSI further based on slot (s) on which the SL CSI request (s) is (are) received and latency bound (s) for SL CSI reporting which may be received from the first UE, wherein each latency bound of the latency bound (s) is associated with a respective RB set of the at least one RB set on which the CSI is determined. Additionally, the SL CSI reporting type may be determined further based on a processing delay for CSI measurement and calculation.

In some examples, as described above, the condition for triggering the combined CSI reporting may be explicitly indicated by the configuration information (e.g. the configuration information may include the condition for triggering the combined CSI reporting) , or may be implicitly defined in UE behaviors. Then, the second UE may determine whether the condition is satisfied based on slot (s) on which the SL CSI request (s) is (are) received and the latency bound (s) for SL CSI reporting for the at least one RB set. In response to determining that the condition is satisfied, the second UE may determine the SL CSI reporting type further based on result (s) of channel access procedure (s) on the at least one RB set.

For example, the condition may be that: a plurality of SL CSI reports, each of which corresponds to an SL CSI-RS confined within an RB set, can be fed back within a same slot when the slots which can be used for transmitting each of the plurality of SL CSI reports overlap in at least one slot.

In such example, the second UE may determine slot (s) which can be used for transmitting each SL CSI report of at least one SL CSI report, wherein each SL CSI report corresponds to an SL CSI-RS confined within a corresponding RB set. The slot (s) which can be used for transmitting each SL CSI report may be determined based on a slot for transmitting the corresponding SL CSI-RS along with the SL CSI request and a latency bound for SL CSI reporting for the corresponding RB set. For example, the slot (s) which can be used for transmitting an SL CSI report is (are) within a time period, which is after a slot n_{CSI_ref} on which the SL CSI-RS is transmitted and before a slot having a time offset (with a value of the latency bound) relative to the slot n_{CSI_ref}. In the case that slot (s) for transmitting each SL CSI report of the at least one SL CSI report overlap in at least one slot, the second UE may determine that the condition for triggering the combined CSI reporting is satisfied.

The following examples may provide several methods for determine the SL CSI reporting type based on result (s) of channel access procedure (s) on the at least one RB set when the combined CSI reporting can be triggered for the at least one RB set.

In some embodiments, if all the at least one RB set (on which CSI is determined) are available for CSI reporting based on the result (s) of channel access procedure (s) , the second UE may determine individual CSI reporting or combined CSI reporting for the at least one RB set in operation 303.

In some embodiments, if not all the at least one RB set (on which CSI is determined) are available for CSI reporting based on the result (s) of channel access procedure (s) , the second UE may determine combined CSI reporting for the at least one RB set in operation 303.

After determining the SL CSI reporting type and the CSI report format, in operation 304, the second UE may transmit at least one SL CSI report on one or more RB sets within the first set of RB sets based on the determined SL CSI reporting type and the determined SL CSI report format.

In an embodiment, the second UE may determine individual CSI reporting and an individual CSI report format for reporting CSI to the first UE. Then, in operation 304, the second UE may transmit at least one SL CSI report on the at least one RB sets on which CSI is determined, wherein each SL CSI report of the at least one SL CSI report is transmitted within an RB set containing the SL CSI-RS to which the determined CSI in the SL CSI report relates. Each SL CSI report may have the determined individual CSI report format, e.g., the individual CSI report format as shown in FIG. 2.

In another embodiment, the second UE may determine combined CSI reporting and a combined CSI report format for reporting CSI to the first UE. Then, in operation 304, the second UE may transmit an SL CSI report on an RB set within the first set of RB sets. The RB set is determined as available for CSI reporting based on a channel access procedure. The SL CSI report carries CSI determined based on the CSI-RS (s) received on the at least one RB set. The SL CSI report may have the determined combined CSI report format.

FIG. 4 illustrates an exemplary method for the second UE to determine SL CSI reporting type according to some embodiments of the present application.

In the example of FIG. 4, it is assumed that the first UE transmits an SL CSI request and SL CSI-RS on each RB set of a first set of RB sets including at least RB set #n, RB set #n+1, and RB set #n+2. The second UE may receive an SL CSI request and SL CSI-RS #1 in slot #m1 in RB set #n, an SL CSI request and SL CSI-RS #2 in slot #m1 in RB set #n+1, and an SL CSI request and SL CSI-RS #3 in slot #m2 in RB set #n+2. For simplicity, FIG. 4 illustrates three adjacent RB sets. It is contemplated that the RB sets on which SL CSI-RSs are received may be not adjacent.

The latency bounds for SL CSI reporting for RB set #n, RB set #n+1, and RB set #n+2 are denoted by latency bound #1, latency bound #2, and latency bound #3, respectively, which may be transmitted from the first UE to the second UE.

The second UE may determine slots (referred to as slot set #1) which can be used for transmitting CSI report corresponding to SL CSI-RS #1 based on slot #m1 and latency bound #1 (for example, the slot set #1 may be after slot #m1 and before a slot having a time offset of latency bound #1 relative to slot #m1) , determine slots (referred to as slot set #2) which can be used for transmitting CSI report corresponding to SL CSI-RS #2 based on slot #m1 and latency bound #2 (for example, the slot set #2 may be after slot #m1 and before a slot having a time offset of latency bound #2 relative to slot #m1) , and determine slots (referred to as slot set #3) which can be used for transmitting CSI report corresponding to SL CSI-RS #3 based on slot #m2 and latency bound #3 (for example, the slot set #3 may be after slot #m2 and before a slot having a time offset of latency bound #3 relative to slot #m2) . In the example of FIG. 4, the slot set #1, slot set #2, and slot set #3 may overlap in at least one slot (e.g., slot #m3) , which means that the combined CSI reporting can be triggered for the three RB sets.

Then, the second UE may determine the SL CSI reporting type based on results of the channel access procedures to slot #m3 on the three RB sets respectively.

In the example of FIG. 4, it is assumed that results of the channel access procedures to slot #m3 show that the channels on RB set #n+1 and RB set #n+2 are available while the channel on RB set #n is busy (i.e., not available) .

As an example, the second UE may determine combined CSI reporting and an SL CSI report format associated with the combined CSI reporting as indicated in the configuration information for reporting CSI corresponding to SL CSI-RS #1, SL CSI-RS #2 and SL CIS-RS #3 in a combined way. The second UE may transmit an SL CSI report with the determined SL CSI report format carrying CSI corresponding to SL CSI-RS #1, SL CSI-RS #2 and SL CSI-RS #3 on slot #m3 on RB set #n+1, RB set #n+2, or any other RB set within the first set of RB sets on which the channel is available at slot #m3.

In some other examples, results of the channel access procedures to slot #m3 may show that the channels on all the three RB sets are available for CSI reporting. Then, the second UE may determine combined CSI reporting or individual CSI reporting for the three RB sets. As an example, the determination may be based on the second UE's implementation. As another example, the determination may be based on a system configuration, e.g., the system configuration may indicate a default CSI reporting type.

As an example, the second UE may determine combined CSI reporting and a CSI report format associated with the combined CSI reporting as indicated in the configuration information for transmitting CSI corresponding to SL CSI-RS #1, SL CSI-RS #2 and SL CSI-RS #3 in a combined way. The second UE may transmit an SL CSI report with the determined SL CSI report format carrying CSI corresponding to SL CSI-RS #1, SL CSI-RS #2 and SL CSI-RS #3 on RB set #n, RB set #n+1, RB set #n+2, or any other RB set within the first set of RB sets on which the channel is available at slot #m3.

As another example, the second UE may determine individual CSI reporting and an individual CSI report format as indicated in the configuration information for transmitting CSI corresponding to SL CSI-RS #1, SL CSI-RS #2 and SL CSI-RS #3, respectively. Then, the second UE may transmit an SL CSI report carrying CSI corresponding to SL CSI-RS #1 in RB set #n, transmit an SL CSI report carrying CSI corresponding to SL CSI-RS #2 in RB set #n+1, and transmit an SL CSI report carrying CSI corresponding to SL CSI-RS #3 in RB set #n+2, wherein each of the SL CSI reports is transmitted by means of the determined individual CSI report format.

In some embodiments, an SL CSI report may be carried by a MAC CE. For example, the MAC CE for carrying an SL CSI report when individual CSI reporting is used may be the same as that for carrying SL CSI report as defined in 3GPP Release 16 or 3GPP Release 17, which includes 8 bits. In another example, a MAC CE adapted to carry a combined CSI report format as described above may be used to carry an SL CSI report when combined CSI reporting is used.

In some embodiments, SCI may be used to carry an SL CSI report when either individual CSI reporting or combined CSI reporting is used. For example, an SL CSI report may be carried in 2^nd stage SCI.

In some embodiments, PSFCH may be used to carry an SL CSI report when either individual CSI reporting or combined CSI reporting is used. In such embodiments, the slot for transmitting the SL CSI report is a slot configured with a PSFCH symbol. The resources in the PSFCH symbol for carrying the SL CSI report may include at least one of:

● PRB (s) not available for HARQ feedback; or

● PRB (s) for HARQ feedback but with different code (s) .

Using PSFCH to carry an SL CSI report is reasonable because new SL CSI reporting can be triggered only if the current SL CSI reporting is received or the latency bound for SL CSI reporting expires. As a result, there is no confusion about the association between SL CSI-RS and corresponding SL CSI reporting, even without extra information for SL CSI reporting.

FIG. 5 illustrates an exemplary PSFCH resource configuration within an RB set (e.g., RB set #n) according to some embodiments of the present application. For simplicity, FIG. 5 illustrates 8 sidelink slots (e.g., slot #n+0 to slot #n+7) in RB set #n, wherein PSFCH symbols are configured in every second slots (e.g., in slot #n+1, slot #n+3, slot #n+5, and slot #n+7) . Then, if an SL CSI report needs to be transmitted in RB set #n, it should be transmitted in the PSFCH symbol in slot #n+1, slot #n+3, slot #n+5, or slot #n+7.

In some embodiments of the present application, the second UE may transmit an SL CSI reporting type indicator indicating the determined SL CSI reporting type to the first UE. In some embodiments, the SL CSI reporting type indicator may be carried in SCI (e.g., in 2^nd-stage SCI) . For example, for each SL CSI report, the second UE may transmit a corresponding SL CSI reporting type indicator to indicate the determined SL CSI reporting type for the SL CSI report. For example, the corresponding SL CSI reporting type indicator and the SL CSI report may be transmitted in the same slot.

Referring back to FIG. 3, in operation 304, the first UE may receive one or more SL CSI reports on one or more RB sets within the first set of RB sets from the second UE. For example, the first UE may monitor the first set of RB sets to receive one or more SL CSI reports on one or more RB sets within the first set of RB sets. The one or more SL CSI reports may be a subset of the at least one SL CSI report transmitted from the second UE.

In operation 305, the first UE may determine CSI in the received one or more SL CSI reports based on the obtained configuration information for SL CSI reporting on the first set of RB sets.

As an example, the configuration information may indicate individual CSI reporting and an individual CSI report format. Then, the first UE may determine CSI in each of the one or more SL CSI reports based on the individual CSI report format. The CSI determined from an SL CSI report is associated with the RB set on which the SL CSI report is received.

As another example, the configuration information may indicate combined CSI reporting and one of the following CSI report formats associated with the combined CSI reporting: a fixed-length CSI report format; a dynamic-length CSI report format; or a differential dynamic-length CSI report format. Then, the first UE may receive an SL CSI report (carrying CSI for at least one RB set) on an RB set within the first set of RB sets and determine CSI for each of the at least one RB set based on the CSI report format indicated by the configuration information.

As yet another example, the configuration information may indicate both individual CSI reporting and combined CSI reporting, an individual CSI report format associated with the individual CSI reporting, and one of the following CSI report formats associated with the combined CSI reporting: a fixed-length CSI report format; a dynamic-length CSI report format; or a differential dynamic-length CSI report format. In such example, the first UE may determine CSI in each SL CSI report further based on an SL CSI reporting type indicator associated with the SL CSI report (e.g., the SL CSI reporting type indicator transmitted in the same slot as the SL CSI report) .

In the case that the SL CSI reporting type indicator associated with the SL CSI report indicates individual CSI reporting, the first UE may determine CSI in the SL CSI report based on the individual CSI report format. The determined CSI is associated with the RB set on which the SL CSI report is received. In the case that the SL CSI reporting type indicator associated with the SL CSI report indicates combined CSI reporting, the first UE may determine CSI for each of at least one RB set from the SL CSI report based on the CSI report format associated with the combined CSI reporting indicated by the configuration information.

According to some embodiments of the present application, a BS may transmit configuration information for SL CSI reporting on a first set of RB sets to one or more UEs (e.g., UE 101a and UE 101b) . All the definitions and designs regarding the configuration information for CSI reporting as described in the above embodiments may also apply here.

In an embodiment, the BS may transmit the configuration information to the one or more UEs via at least one of a MIB message, a SIB message, an RRC signaling, a MAC CE, or DCI.

FIG. 6 illustrates a simplified block diagram of an exemplary apparatus 600 for SL CSI reporting over unlicensed spectra according to some embodiments of the present application. In some embodiments, the apparatus 600 may be or include at least part of a UE (e.g., UE 101a or UE 101b in FIG. 1) . In some other embodiments, the apparatus 600 may be or include at least part of a BS (e.g., BS 102 in FIG. 1) .

Referring to FIG. 6, the apparatus 600 may include at least one transceiver 602 and at least one processor 606. The at least one transceiver 602 is coupled to the at least one processor 606.

Although in this figure, elements such as the transceiver 602 and the processor 606 are illustrated in the singular, the plural is contemplated unless a limitation to the singular is explicitly stated. In some embodiments of the present application, the transceiver 602 may be divided into two devices, such as receiving circuitry (or a receiver) and transmitting circuitry (or a transmitter) . In some embodiments of the present application, the apparatus 600 may further include an input device, a memory, and/or other components. The transceiver 602 and the processor 606 may be configured to perform any of the methods described herein (e.g., the methods described with respect to FIGS. 2-5 or other methods described in the embodiments of the present application) .

According to some embodiments of the present application, the apparatus 600 may be a CSI triggering UE, which transmits CSI-RS (s) , and the transceiver 602 and the processor 606 may be configured to perform operations of a CSI triggering UE in any of the methods as described with respect to FIGS. 2-5 or other methods described in the embodiments of the present application. For example, the processor 606 is configured to: obtain configuration information for SL CSI reporting on a first set of RB sets, wherein the configuration information indicates: SL CSI reporting type (s) ; and SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) ; and transmit, via the transceiver 602, an SL CSI request and SL CSI-RS on each RB set of a second set of RB sets individually to another UE (e.g., a CSI reporting UE) , wherein the second set of RB sets is a subset of the first set of RB sets.

According to some embodiments of the present application, the apparatus 600 may be a CSI reporting UE, which transmits CSI report (s) , and the transceiver 602 and the processor 606 may be configured to perform operations of a CSI reporting UE in any of the methods as described with respect to FIGS. 2-5 or other methods described in the embodiments of the present application. For example, the processor 606 is configured to: receive, via the transceiver 602, an SL CSI request and SL CSI-RS on each RB set of a first set of RB sets individually from another UE (e.g., a CSI triggering UE) ; determine CSI based on SL CSI-RS (s) received on at least one RB set of the first set of RB sets; and determine an SL CSI reporting type and an SL CSI report format associated with the SL CSI reporting type for reporting the CSI to the another UE.

According to some embodiments of the present application, the apparatus 600 may be a BS, and the transceiver 602 and the processor 606 may be configured to perform operations of a BS described in the embodiments of the present application. For example, the processor 606 is configured to: transmit, via the transceiver 602, configuration information for SL CSI reporting on a first set of RB sets, wherein the configuration information indicates: SL CSI reporting type (s) ; and SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) .

In some embodiments of the present application, the apparatus 600 may further include at least one non-transitory computer-readable medium. In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 606 to implement any of the methods as described above. For example, the computer-executable instructions, when executed, may cause the processor 606 to interact with the transceiver 602, so as to perform operations of the methods, e.g., as described with respect to FIGS. 2-5 or other methods described in the embodiments of the present application.

The method according to any of the embodiments of the present application can also be implemented on a programmed processor. However, the controllers, flowcharts, and modules may also be implemented on a general purpose or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit such as a discrete element circuit, a programmable logic device, or the like. In general, any device on which resides a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processor functions of this application. For example, an embodiment of the present application provides an apparatus for SL CSI reporting over unlicensed spectra, including a processor and a memory. Computer programmable instructions for implementing a method for SL CSI reporting over unlicensed spectra are stored in the memory, and the processor is configured to perform the computer programmable instructions to implement the method for SL CSI reporting over unlicensed spectra. The method for SL CSI reporting over unlicensed spectra may be any method as described in the present application.

An alternative embodiment preferably implements the methods according to embodiments of the present application in a non-transitory, computer-readable storage medium storing computer programmable instructions. The instructions are preferably executed by computer-executable components preferably integrated with a network security system. The non-transitory, computer-readable storage medium may be stored on any suitable computer readable media such as RAMs, ROMs, flash memory, EEPROMs, optical storage devices (CD or DVD) , hard drives, floppy drives, or any suitable device. The computer-executable component is preferably a processor but the instructions may alternatively or additionally be executed by any suitable dedicated hardware device. For example, an embodiment of the present application provides a non-transitory, computer-readable storage medium having computer programmable instructions stored therein. The computer programmable instructions are configured to implement a method for SL CSI reporting over unlicensed spectra according to any embodiment of the present application.

While this application has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements of each figure are not necessary for operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments would be enabled to make and use the teachings of the application by simply employing the elements of the independent claims. Accordingly, embodiments of the application as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the application.

In this disclosure, relational terms such as "first, " "second, " and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises, " "comprising, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Also, the term "another" is defined as at least a second or more. The terms "including, " "having, " and the like, as used herein, are defined as "comprising. "

Claims

A first user equipment (UE) , comprising:

a transceiver; and

a processor coupled to the transceiver and configured to:

obtain configuration information for sidelink (SL) channel state information (CSI) reporting on a first set of resource block (RB) sets, wherein the configuration information indicates:

SL CSI reporting type (s) ; and

SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) ; and

transmit, via the transceiver, an SL CSI request and SL CSI reference signal (RS) on each RB set of a second set of RB sets individually to a second UE, wherein the second set of RB sets is a subset of the first set of RB sets.
The first UE of Claim 1, wherein the SL CSI reporting type (s) includes at least one of:

individual CSI reporting; or

combined CSI reporting.
The first UE of Claim 2, wherein the SL CSI report format (s) includes at least one of:

an individual CSI report format associated with the individual CSI reporting; or

one of the following CSI report formats associated with the combined CSI reporting:

a fixed-length CSI report format;

a dynamic-length CSI report format; or

a differential dynamic-length CSI report format.
The first UE of Claim 1, wherein the processor is further configured to:

receive, via the transceiver and from the second UE, at least one SL CSI report on at least one RB set within the first set of RB sets; and

determine CSI in the at least one SL CSI report based on the obtained configuration information.
The first UE of Claim 4, wherein:

CSI in each SL CSI report is determined further based on an SL CSI reporting type indicator associated with the SL CSI report.
A second user equipment (UE) , comprising:

a transceiver; and

a processor coupled to the transceiver and configured to:

receive, via the transceiver, a sidelink (SL) channel state information (CSI) request and SL CSI reference signal (RS) on each resource block (RB) set of a first set of RB sets individually from a first UE;

determine CSI based on SL CSI-RS (s) received on at least one RB set of the first set of RB sets; and

determine an SL CSI reporting type and an SL CSI report format associated with the SL CSI reporting type for reporting the CSI to the first UE.
The second UE of Claim 6, wherein the SL CSI reporting type and the SL CSI report format are determined based on configuration information for SL CSI reporting on a second set of RB sets, wherein the configuration information indicates:

SL CSI reporting type (s) ; and

SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) ;

wherein the first set of RB sets is a subset of the second set of RB sets.
The second UE of Claim 7, wherein the SL CSI reporting type (s) includes at least one of:

individual CSI reporting; or

combined CSI reporting.
The second UE of Claim 8, wherein the SL CSI report format (s) includes at least one of:

an individual CSI report format associated with the individual CSI reporting; or

one of the following CSI report formats associated with the combined CSI reporting:

a fixed-length CSI report format;

a dynamic-length CSI report format; or

a differential dynamic-length CSI report format.
The second UE of Claim 7, wherein the SL CSI reporting type is determined further based on slot (s) on which the SL CSI request (s) is (are) received and latency bound (s) for SL CSI reporting, wherein each latency bound is associated with a respective RB set of the at least one RB set.
The second UE of Claim 7, wherein the processor is further configured to transmit, via the transceiver, at least one SL CSI report on one or more RB sets within the second set of RB sets based on the determined SL CSI reporting type and the determined SL CSI report format.
The second UE of Claim 11, wherein:

in the case that the determined SL CSI reporting type is individual CSI reporting:

each SL CSI report of the at least one SL CSI report is transmitted within an RB set containing the SL CSI-RS to which the determined CSI in the SL CSI report relates; or

in the case that the determined SL CSI reporting type is combined CSI reporting:

the processor is configured to transmit an SL CSI report on an RB set within the second set of RB sets, wherein the SL CSI report carries CSI determined based on the CSI-RS (s) received on the at least one RB set within the first set of RB sets.
The second UE of Claim 11, wherein an SL CSI report of the at least one SL CSI report is carried by one of the follows:

medium access control (MAC) control element (CE) ;

sidelink control information (SCI) ; or

physical sidelink feedback channel (PSFCH) .
The second UE of Claim 6, wherein the processor is further configured to transmit, via the transceiver, an SL CSI reporting type indicator indicating the determined SL CSI reporting type to the first UE.
A base station (BS) , comprising:

a transceiver; and

a processor coupled to the transceiver and configured to:

transmit, via the transceiver, configuration information for sidelink (SL) channel state information (CSI) reporting on a first set of resource block (RB) sets, wherein the configuration information indicates:

SL CSI reporting type (s) ; and

SL CSI report format (s) , each SL CSI report format associated with a respective SL CSI reporting type of the SL CSI reporting type (s) .