WO2024159801A1

WO2024159801A1 - Sidelink reference signal framework

Info

Publication number: WO2024159801A1
Application number: PCT/CN2023/124093
Authority: WO
Inventors: Xin Guo; Haipeng Lei; Zhennian SUN
Original assignee: Lenovo Beijing Ltd
Current assignee: Lenovo Beijing Ltd
Priority date: 2023-10-11
Filing date: 2023-10-11
Publication date: 2024-08-08
Anticipated expiration: 2026-04-11

Abstract

Various aspects of the present disclosure relate to a sidelink reference signal framework. In some embodiments, a user equipment (UE) determines a slot for transmitting one or more sidelink reference signals. Moreover, the UE transmits the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals. In this way, it is possible to improve the sidelink communications with enhanced efficiency.

Description

SIDELINK REFERENCE SIGNAL FRAMEWORK

TECHNICAL FIELD

The present disclosure relates to wireless communications, and more specifically to a sidelink reference signal framework.

BACKGROUND

A wireless communications system may include one or multiple network communication devices, such as base stations, which may be otherwise known as an eNodeB (eNB) , a next-generation NodeB (gNB) , or other suitable terminology. Each network communication devices, such as a base station may support wireless communications for one or multiple user communication devices, which may be otherwise known as user equipment (UE) , or other suitable terminology. The wireless communications system may support wireless communications with one or multiple user communication devices by utilizing resources of the wireless communication system (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers) . Additionally, the wireless communications system may support wireless communications across various radio access technologies including third generation (3G) radio access technology, fourth generation (4G) radio access technology, fifth generation (5G) radio access technology, among other suitable radio access technologies beyond 5G (e.g., sixth generation (6G) ) .

A sidelink reference signal has been introduced to facilitate sidelink communications. For example, a sidelink channel state information reference signal (SL CSI-RS) transmitted by a transmitting (TX) UE is used for measuring channel state information (CSI) at a receiving (RX) UE. The CSI is then fed back by the RX UE to the TX UE. The TX UE may adjust its transmission based on the fed-back CSI. The design of the SL CSI-RS is based on the CSI-RS design of release 15 (Rel-15) NR Uu. However, enhancements on the sidelink reference signal framework are still needed.

SUMMARY

The present disclosure relates to methods, apparatuses, and systems that support a sidelink reference signal framework. With the apparatuses and methods, it is possible to improve the sidelink communications with enhanced efficiency.

In a first aspect, there is provided a UE. The UE comprises at least one memory; and at least one processor coupled with the at least one memory and configured to cause the UE to: determine a slot for transmitting one or more sidelink reference signals; and transmit the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

In a second aspect, there is provided a method performed by the UE. The method comprises: determining a slot for transmitting one or more sidelink reference signals; and transmitting the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

In a third aspect, there is provided a processor for wireless communication. The at least one processor comprises at least one controller coupled with at least one memory and configured to cause the at least one processor to: determine a slot for transmitting one or more sidelink reference signals; and transmit the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

In some implementations of the method and the UE described herein, configuration information of a slot structure of the slot comprises information on one of the following: one or more automatic gain control (AGC) symbols associated with the one or more sidelink reference signals; one or more gap symbols; one or more physical sidelink control channel (PSCCH) symbols carrying the one or more SCIs; one or more symbols carrying the one or more sidelink reference signals; or one or more frequency allocations of the one or more sidelink reference signals.

In some implementations of the method and the UE described herein, the configuration information is configured by a network equipment or pre-configured.

In some implementations of the method and the UE described herein, the configuration information is configured via one of the following: a master information block (MIB) message; a system information block (SIB) message; a radio resource control (RRC) signaling; a medium access control (MAC) control element (CE) ; or downlink control information (DCI) .

In some implementations of the method and the UE described herein, the slot structure is pre-configured or configured per resource pool or per bandwidth part.

In some implementations of the method and the UE described herein, the one or more sidelink reference signals comprise a plurality of sidelink reference signals, and the slot structure comprises one of the following: a first slot structure, in which a plurality of beams are used for transmitting the plurality of sidelink reference signals, and wherein the one or more SCIs comprise a plurality of SCIs, and the slot comprises a plurality of ACG symbols and a plurality of PSCCH symbols, an ACG symbol of the plurality of ACG symbols and a PSCCH symbol of the plurality of PSCCH symbols correspond to a sidelink reference signal of the plurality of sidelink reference signals, a beam of the plurality of beams being associated with an SCI of the plurality of SCIs carried in a PSCCH symbol of the plurality of PSCCH symbols; or a second slot structure, in which a same beam is used for transmitting the plurality of sidelink reference signals and wherein the one or more SCIs comprise one SCI, and the slot comprises an ACG symbol and a PSCCH symbol, the ACG symbol and the PSCCH symbol corresponding to the plurality of sidelink reference signals, the same beam being associated with the one SCI carried in the PSCCH symbol.

In some implementations of the method and the UE described herein, one of the first slot structure or the second slot structure is pre-configured or configured for a resource pool in which the slot is in.

In some implementations of the method and the UE described herein, the first slot structure and the second slot structure are pre-configured or configured for a resource pool in which the slot is in, and the configuration information further comprises a bitmap indicating whether the first slot structure or the second slot structure is applied for each of a plurality of slots within the resource pool.

In some implementations of the method and the UE described herein, the first slot structure and the second slot structure are pre-configured or configured for a resource pool in which the slot is in, and the configuration information further comprises one of the following: a first periodicity and a second periodicity, the first periodicity indicating a distribution of the first slot structure in the resource pool and the second periodicity indicating a distribution of the second slot structure in the resource pool; or a first slot offset and a second slot offset, the first slot offset indicating a distribution of the first slot structure in the resource pool and the second slot offset indicating a distribution of the second slot structure in the resource pool.

In some implementations of the method and the UE described herein, the configuration information comprises information on the one or more frequency allocations of the one or more sidelink reference signals, and whether the one or more sidelink reference signals use a same frequency allocation or not is indicated by one of the following: a number of frequency allocations in the configuration information of the slot; or a frequency allocation indicator to indicate whether the one or more sidelink reference signals use a same frequency allocation or not.

In some implementations of the method and the UE described herein, the beam information comprises one of the following: one or more beam indexes for transmitting the one or more sidelink reference signals; or a parameter indicating whether a same beam is used for transmitting the one or more sidelink reference signals.

In some implementations of the method and the UE described herein, the one or more SCIs further comprises one of the following: a number of the one or more sidelink reference signals, the number of the one or more sidelink reference signals being less than or equal to a total number of reference signal occasions within the slot; or a bitmap indicating one or more locations of the one or more sidelink reference signals.

In a fourth aspect, there is provided a network equipment (NE) . The NE comprises at least one memory; and at least one processor coupled with the at least one memory and configured to cause the NE to: transmit, to a UE, configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

In a fifth aspect, there is provided a method performed by the NE. The method comprises: transmitting, to a UE, configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

In a sixth aspect, there is provided a processor for wireless communication. The at least one processor comprises at least one controller coupled with at least one memory and configured to cause the at least one processor to: transmit, to a UE, configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

In some implementations of the method and the NE described herein, the configuration information comprises information on one of the following: one or more automatic gain control (AGC) symbols associated with the one or more sidelink reference signals; one or more gap symbols; one or more physical sidelink control channel (PSCCH) symbols carrying the one or more SCIs; one or more symbols carrying the one or more sidelink reference signals; or one or more frequency allocations of the one or more sidelink reference signals.

In some implementations of the method and the NE described herein, the configuration information is transmitted via one of the following: a master information block (MIB) message; a system information block (SIB) message; a radio resource control (RRC) signaling; a medium access control (MAC) control element (CE) ; or downlink control information (DCI) .

In some implementations of the method and the NE described herein, the slot structure is configured per resource pool or per bandwidth part.

In some implementations of the method and the NE described herein, the one or more sidelink reference signals comprise a plurality of sidelink reference signals, and the slot structure comprises one of the following: a first slot structure, in which a plurality of beams are used for transmitting the plurality of sidelink reference signals, and wherein the one or more SCIs comprise a plurality of SCIs, and the slot comprises a plurality of ACG symbols and a plurality of PSCCH symbols, an ACG symbol of the plurality of ACG symbols and a PSCCH symbol of the plurality of PSCCH symbols correspond to a sidelink reference signal of the plurality of sidelink reference signals, a beam of the plurality of beams being associated with an SCI of the plurality of SCIs carried in a PSCCH symbol of the plurality of PSCCH symbols; or a second slot structure, in which a same beam is used for transmitting the plurality of sidelink reference signals and wherein the one or more SCIs comprise one SCI, and the slot comprises an ACG symbol and a PSCCH symbol, the ACG symbol and the PSCCH symbol corresponding to the plurality of sidelink reference signals, the same beam being associated with the one SCI carried in the PSCCH symbol.

In some implementations of the method and the NE described herein, one of the first slot structure or the second slot structure is configured for a resource pool in which the slot is in.

In some implementations of the method and the NE described herein, the first slot structure and the second slot structure are configured for a resource pool in which the slot is in, and the configuration information further comprises a bitmap indicating whether the first slot structure or the second slot structure is applied for each of a plurality of slots within the resource pool.

In some implementations of the method and the NE described herein, the first slot structure and the second slot structure are configured for a resource pool in which the slot is in, and the configuration information further comprises one of the following: a first periodicity and a second periodicity, the first periodicity indicating a distribution of the first slot structure in the resource pool and the second periodicity indicating a distribution of the second slot structure in the resource pool; or a first slot offset and a second slot offset, the first slot offset indicating a distribution of the first slot structure in the resource pool and the second slot offset indicating a distribution of the second slot structure in the resource pool.

In some implementations of the method and the NE described herein, the configuration information comprises information on the one or more frequency allocations of the one or more sidelink reference signals, and whether the one or more sidelink reference signals use a same frequency allocation or not is indicated by one of the following: a number of frequency allocations in the configuration information of the slot; or a frequency allocation indicator to indicate whether the one or more sidelink reference signals use a same frequency allocation or not.

In some implementations of the method and the NE described herein, the beam information comprises one of the following: one or more beam indexes for transmitting the one or more sidelink reference signals; or a parameter indicating whether a same beam is used for transmitting the one or more sidelink reference signals.

In some implementations of the method and the NE described herein, the one or more SCIs further comprises one of the following: a number of the one or more sidelink reference signals, the number of the one or more sidelink reference signals being less than or equal to a total number of reference signal occasions within the slot; or a bitmap indicating one or more locations of the one or more sidelink reference signals.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system that supports a sidelink reference signal framework in accordance with aspects of the present disclosure;

FIGS. 2A and 2B illustrate example process flows in accordance with some example embodiments of the present disclosure;

FIG. 3A illustrates a first example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3B illustrates an example mapping pattern in accordance with some example embodiments of the present disclosure;

FIG. 3C illustrates a second example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3D illustrates a third example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3E illustrates a fourth example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3F illustrates a fifth example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3G illustrates a sixth example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3H illustrates a seventh example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3I illustrates an eighth example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 3J illustrates a ninth example slot structure in accordance with some example embodiments of the present disclosure;

FIG. 4 illustrates an example of a device that supports a sidelink reference signal framework in accordance with aspects of the present disclosure; and

FIG. 5 illustrates an example of a processor that supports a sidelink reference signal framework in accordance with aspects of the present disclosure.

FIGS. 6 through 7 illustrate flowcharts of methods that support a sidelink reference signal framework in accordance with aspects of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION

Principles of the present disclosure will now be described with reference to some embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment, ” “an example embodiment, ” “an embodiment, ” “some embodiments, ” and the like indicate that the embodiment (s) described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment (s) . Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” or the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could also be termed as a second element, and similarly, a second element could also be termed as a first element, without departing from the scope of embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms. In some examples, values, procedures, or apparatuses are referred to as “best, ” “lowest, ” “highest, ” “minimum, ” “maximum, ” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of embodiments. As used herein, the singular forms “a, ” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises, ” “comprising, ” “has, ” “having, ” “includes” and/or “including, ” when used herein, specify the presence of stated features, elements, components and/or the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. For example, the term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to. ” The term “based on” is to be read as “based at least in part on. ” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment. ” The term “another embodiment” is to be read as “at least one other embodiment. ” The use of an expression such as “A and/or B” can mean either “only A” or “only B” or “both A and B. ” Other definitions, explicit and implicit, may be included below.

As mentioned above, the SL CSI-RS is used for measuring the CSI at the RX UE that is then fed back to the TX UE. The TX UE may adjust its transmission based on the fed-back CSI. The SL CSI-RS is sent within a physical sidelink shared channel (PSSCH) region of a slot.

In new radio (NR) vehicle to everything (V2X) , the transmission of the SL CSI-RS is supported for unicast transmissions only. The NR V2X also supports CSI reporting in unicast communications. The RX UE can measure the CSI and report it back to the TX UE via CSI reporting carried within a PSSCH. To request the CSI feedback from the RX UE, a one-bit CSI request is sent in the 2nd-stage SCI with SCI format 2-A.

The transmission of the SL CSI-RS by the TX UE along with a CSI request sent in the 2nd-stage SCI triggers the RX UE of a unicast link to feed back a CSI report. The TX UE may configure aperiodic CSI reporting from the RX UE. The RX UE may measure the CSI based on the SL CSI-RS sent by the TX UE. The RX UE feeds back to the TX UE the CSI (for example, a channel quality indicator (CQI) or a rank indicator (RI) ) via CSI reporting over a PSSCH. The CSI report is carried in a media access control (MAC) control element (CE) over a PSSCH sent from the RX UE to the TX UE.

To avoid outdated CSI, the RX UE is expected to feed back the CSI report within a maximum amount of time. This maximum amount of time is referred to as a latency bound. The latency bound is determined by the TX UE and signaled to the RX UE via a proximity services (ProSe) Communication 5 (PC5) radio resource control (PC5-RRC) signaling.

The design of the SL CSI-RS is based on the CSI-RS design of Rel-15 NR Uu. In addition, the resource mapping of the SL CSI-RS in a PRB is based on a CSI-RS resource mapping pattern in NR Uu, which support up to two antenna ports (as in NR V2X SL, where up to two streams may be supported in a PSSCH) . Each physical resource block (PRB) within the PSSCH uses the same pattern for the SL CSI-RS. The SL CSI- RS is not transmitted on symbols containing a physical sidelink control channel (PSCCH) , the 2nd-stage SCI, or a PSSCH DMRS.

The SL CSI-RS configuration includes a resource mapping pattern and the number of antenna ports for the SL CSI-RS. The SL CSI-RS configuration is selected by the TX UE and provided to the RX UE via a proximity services (ProSe) Communication 5 (PC5) -RRC configuration.

Moreover, in release 18 (Rel-18) , a new study item description (SID) on sidelink evolution was approved, which includes an objective of an enhanced operation on the frequency range 2 (FR2) licensed spectrum. More considerations on supporting beam management (for example, initial beam pairing (IBP) ) over sidelink in the FR2 need to be given.

Before or during unicast sidelink communication established between the TX UE and the RX UE, both the TX UE and the RX UE have no information to determine which TX/RX beam (s) to be used between them. In such a case, prior knowledge related to beaming-sweeping is needed for UEs to perform initial beam paring. The knowledge includes the TX beam-sweeping pattern (e.g., resources for transmitting reference signals and TX beams used for the transmission) of the TX UE for monitoring reference signal (s) and RX beam-sweeping pattern of the RX UE for indicating the selected beam or beam pair. That is to say, a beam-sweeping pattern (s) based on the (pre-) configuration is needed for the TX UE and the RX UE to perform initial beam pairing before/during unicast sidelink communication establishment. In NR V2X as specified in third generation partnership project (3GPP) Rel-16/release 17 (Rel-17) , the transmission of SL CSI-RS supported for unicast transmissions is used for beam management.

Inventors have noticed that from signaling overhead perspectives, beam-sweeping pattern configuration supporting periodic reference signal transmission is efficient in this scenario. To support the periodic SL CSI-RS framework, standalone CSI-RS transmission is needed. The standalone SL CSI-RS transmission means at least no accompanying sidelink data (SL MAC service data unit (SDU) ) transmissions in the same slot.

In the case of resource allocation mode 2, a dedicated resource pool is needed to support periodic SL CSI-RS transmission. The reason is that since the sidelink resources are determined based on sensing, each CSI-RS transmission may experience intolerable latency due to resource selection if the network is in a heavy traffic load.

In the case of resource allocation mode 1, a resource pool shared between periodic SL CSI-RS transmission and PSSCH/PSCCH transmissions may be possible. In addition, a dedicated resource pool may be applied for standalone SL CSI-RS.

As of now, there is no effective slot framework to support sidelink transmissions, especially for beam management (including initial beam pairing, or beam maintenance) . To fulfill the above requirements, there is a need for a new structure of a sidelink reference to support the beam management over sidelink in the FR2.

Embodiments of the present disclosure provide a solution for a sidelink reference signal framework. In one aspect of the solution of the present disclosure, a UE determines a slot for transmitting one or more sidelink reference signals. Moreover, the UE transmits the one or more sidelink reference signals in the slot. One or more SCIs associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

By transmitting one or more sidelink reference signals in the slot, this solution can improve spectrum efficiency for sidelink reference signal transmissions. Moreover, by comprising beam information in the one or more SCIs, it is allowed to facilitate TX beam sweeping and RX beam sweeping. In this way, it is possible to improve the sidelink communications with enhanced efficiency.

Principles and implementations of embodiments of the present disclosure will be described in detail below with reference to the figures.

FIG. 1 illustrates an example of a wireless communications system 100 that supports a sidelink reference signal framework in accordance with aspects of the present disclosure. The wireless communications system 100 may include one or more network entities 102 (also referred to as network equipment (NE) ) , one or more UEs 104, a core network 106, and a packet data network 108. The wireless communications system 100 may support various radio access technologies. In some implementations, the wireless communications system 100 may be a 4G network, such as a long term evolution (LTE) network or an LTE-Advanced (LTE-A) network. In some other implementations, the wireless communications system 100 may be a 5G network, such as a new radio (NR) network. In other implementations, the wireless communications system 100 may be a combination of a 4G network and a 5G network, or other suitable radio access technology including Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20. The wireless communications system 100 may support radio access technologies beyond 5G. Additionally, the wireless communications system 100 may support technologies, such as time division multiple access (TDMA) , frequency division multiple access (FDMA) , or code division multiple access (CDMA) , etc.

The one or more network entities 102 may be dispersed throughout a geographic region to form the wireless communications system 100. One or more of the network entities 102 described herein may be or include or may be referred to as a network node, a base station, a network element, a radio access network (RAN) , a base transceiver station, an access point, a NodeB, an eNodeB (eNB) , a next-generation NodeB (gNB) , or other suitable terminology. A network entity 102 and a UE 104 may communicate via a communication link 110, which may be a wireless or wired connection. For example, a network entity 102 and a UE 104 may perform wireless communication (e.g., receive signaling, transmit signaling) over a Uu interface.

A network entity 102 may provide a geographic coverage area 112 for which the network entity 102 may support services (e.g., voice, video, packet data, messaging, broadcast, etc. ) for one or more UEs 104 within the geographic coverage area 112. For example, a network entity 102 and a UE 104 may support wireless communication of signals related to services (e.g., voice, video, packet data, messaging, broadcast, etc. ) according to one or multiple radio access technologies. In some implementations, a network entity 102 may be moveable, for example, a satellite associated with a non-terrestrial network. In some implementations, different geographic coverage areas 112 associated with the same or different radio access technologies may overlap, but the different geographic coverage areas 112 may be associated with different network entities 102. Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The one or more UEs 104 may be dispersed throughout a geographic region of the wireless communications system 100. A UE 104 may include or may be referred to as a mobile device, a wireless device, a remote device, a remote unit, a handheld device, or a subscriber device, or some other suitable terminology. In some implementations, the UE 104 may be referred to as a unit, a station, a terminal, or a client, among other examples. Additionally, or alternatively, the UE 104 may be referred to as an Internet-of-Things (IoT) device, an Internet-of-Everything (IoE) device, or machine-type communication (MTC) device, among other examples. In some implementations, a UE 104 may be stationary in the wireless communications system 100. In some other implementations, a UE 104 may be mobile in the wireless communications system 100.

The one or more UEs 104 may be devices in different forms or having different capabilities. Some examples of UEs 104 are illustrated in FIG. 1. A UE 104 may be capable of communicating with various types of devices, such as the network entities 102, other UEs 104, or network equipment (e.g., the core network 106, the packet data network 108, a relay device, an integrated access and backhaul (IAB) node, or another network equipment) , as shown in FIG. 1. Additionally, or alternatively, a UE 104 may support communication with other network entities 102 or UEs 104, which may act as relays in the wireless communications system 100.

A UE 104 may also be able to support wireless communication directly with other UEs 104 over a communication link 114. For example, a UE 104 may support wireless communication directly with another UE 104 over a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, the communication link 114 may be referred to as a sidelink (SL) . For example, a UE 104 may support wireless communication directly with another UE 104 over a PC5 interface.

A network entity 102 may support communications with the core network 106, or with another network entity 102, or both. For example, a network entity 102 may interface with the core network 106 through one or more backhaul links 116 (e.g., via an S1, N2, N2, or another network interface) . The network entities 102 may communicate with each other over the backhaul links 116 (e.g., via an X2, Xn, or another network interface) . In some implementations, the network entities 102 may communicate with each other directly (e.g., between the network entities 102) . In some other implementations, the network entities 102 may communicate with each other or indirectly (e.g., via the core network 106) . In some implementations, one or more network entities 102 may include subcomponents, such as an access network entity, which may be an example of an access node controller (ANC) . An ANC may communicate with the one or more UEs 104 through one or more other access network transmission entities, which may be referred to as a radio heads, smart radio heads, or transmission-reception points (TRPs) .

In some implementations, a network entity 102 may be configured in a disaggregated architecture, which may be configured to utilize a protocol stack physically or logically distributed among two or more network entities 102, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance) , or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN) ) . For example, a network entity 102 may include one or more of a central unit (CU) , a distributed unit (DU) , a radio unit (RU) , a RAN Intelligent Controller (RIC) (e.g., a Near-Real Time RIC (Near-RT RIC) , a Non-Real Time RIC (Non-RT RIC) ) , a Service Management and Orchestration (SMO) system, or any combination thereof.

An RU may also be referred to as a radio head, a smart radio head, a remote radio head (RRH) , a remote radio unit (RRU) , or a transmission reception point (TRP) . One or more components of the network entities 102 in a disaggregated RAN architecture may be co-located, or one or more components of the network entities 102 may be located in distributed locations (e.g., separate physical locations) . In some implementations, one or more network entities 102 of a disaggregated RAN architecture may be implemented as virtual units (e.g., a virtual CU (VCU) , a virtual DU (VDU) , a virtual RU (VRU) ) .

Split of functionality between a CU, a DU, and an RU may be flexible and may support different functionalities depending upon which functions (e.g., network layer functions, protocol layer functions, baseband functions, radio frequency functions, and any combinations thereof) are performed at a CU, a DU, or an RU. For example, a functional split of a protocol stack may be employed between a CU and a DU such that the CU may support one or more layers of the protocol stack and the DU may support one or more different layers of the protocol stack. In some implementations, the CU may host upper protocol layer (e.g., a layer 3 (L3) , a layer 2 (L2) ) functionality and signaling (e.g., Radio Resource Control (RRC) , service data adaption protocol (SDAP) , Packet Data Convergence Protocol (PDCP) ) . The CU may be connected to one or more DUs or RUs, and the one or more DUs or RUs may host lower protocol layers, such as a layer 1 (L1) (e.g., physical (PHY) layer) or an L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU.

Additionally, or alternatively, a functional split of the protocol stack may be employed between a DU and an RU such that the DU may support one or more layers of the protocol stack and the RU may support one or more different layers of the protocol stack. The DU may support one or multiple different cells (e.g., via one or more RUs) . In some implementations, a functional split between a CU and a DU, or between a DU and an RU may be within a protocol layer (e.g., some functions for a protocol layer may be performed by one of a CU, a DU, or an RU, while other functions of the protocol layer are performed by a different one of the CU, the DU, or the RU) .

A CU may be functionally split further into CU control plane (CU-CP) and CU user plane (CU-UP) functions. A CU may be connected to one or more DUs via a midhaul communication link (e.g., F1, F1 c, F1 u) , and a DU may be connected to one or more RUs via a fronthaul communication link (e.g., open fronthaul (FH) interface) . In some implementations, a midhaul communication link or a fronthaul communication link may be implemented in accordance with an interface (e.g., a channel) between layers of a protocol stack supported by respective network entities 102 that are in communication via such communication links .

The core network 106 may support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. The core network 106 may be an evolved packet core (EPC) , or a 5G core (5GC) , which may include a control plane entity that manages access and mobility (e.g., a mobility management entity (MME) , an access and mobility management functions (AMF) ) and a user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . In some implementations, the control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management (e.g., data bearers, signal bearers, etc. ) for the one or more UEs 104 served by the one or more network entities 102 associated with the core network 106.

The core network 106 may communicate with the packet data network 108 over one or more backhaul links 116 (e.g., via an S1, N2, N3, or another network interface) . The packet data network 108 may include an application server 118. In some implementations, one or more UEs 104 may communicate with the application server 118. A UE 104 may establish a session (e.g., a protocol data unit (PDU) session, or the like) with the core network 106 via a network entity 102. The core network 106 may route traffic (e.g., control information, data, and the like) between the UE 104 and the application server 118 using the established session (e.g., the established PDU session) . The PDU session may be an example of a logical connection between the UE 104 and the core network 106 (e.g., one or more network functions of the core network 106) .

In the wireless communications system 100, the network entities 102 and the UEs 104 may use resources of the wireless communications system 100 (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers) ) to perform various operations (e.g., wireless communications) . In some implementations, the network entities 102 and the UEs 104 may support different resource structures. For example, the network entities 102 and the UEs 104 may support different frame structures. In some implementations, such as in 4G, the network entities 102 and the UEs 104 may support a single frame structure. In some other implementations, such as in 5G and among other suitable radio access technologies, the network entities 102 and the UEs 104 may support various frame structures (i.e., multiple frame structures) . The network entities 102 and the UEs 104 may support various frame structures based on one or more numerologies.

One or more numerologies may be supported in the wireless communications system 100, and a numerology may include a subcarrier spacing and a cyclic prefix. A first numerology (e.g., μ=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a normal cyclic prefix. In some implementations, the first numerology (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one slot per subframe. A second numerology (e.g., μ=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a normal cyclic prefix. A third numerology (e.g., μ=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a normal cyclic prefix or an extended cyclic prefix. A fourth numerology (e.g., μ=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a normal cyclic prefix. A fifth numerology (e.g., μ=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a normal cyclic prefix.

A time interval of a resource (e.g., a communication resource) may be organized according to frames (also referred to as radio frames) . Each frame may have a duration, for example, a 10 millisecond (ms) duration. In some implementations, each frame may include multiple subframes. For example, each frame may include 10 subframes, and each subframe may have a duration, for example, a 1 ms duration. In some implementations, each frame may have the same duration. In some implementations, each subframe of a frame may have the same duration.

Additionally or alternatively, a time interval of a resource (e.g., a communication resource) may be organized according to slots. For example, a subframe may include a number (e.g., quantity) of slots. The number of slots in each subframe may also depend on the one or more numerologies supported in the wireless communications system 100. For instance, the first, second, third, fourth, and fifth numerologies (i.e., μ=0, μ=1, μ=2, μ=3, μ=4) associated with respective subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz may utilize a single slot per subframe, two slots per subframe, four slots per subframe, eight slots per subframe, and 16 slots per subframe, respectively. Each slot may include a number (e.g., quantity) of symbols (e.g., OFDM symbols) . In some implementations, the number (e.g., quantity) of slots for a subframe may depend on a numerology. For a normal cyclic prefix, a slot may include 14 symbols. For an extended cyclic prefix (e.g., applicable for 60 kHz subcarrier spacing) , a slot may include 12 symbols. The relationship between the number of symbols per slot, the number of slots per subframe, and the number of slots per frame for a normal cyclic prefix and an extended cyclic prefix may depend on a numerology. It should be understood that reference to a first numerology (e.g., μ=0) associated with a first subcarrier spacing (e.g., 15 kHz) may be used interchangeably between subframes and slots.

In the wireless communications system 100, an electromagnetic (EM) spectrum may be split, based on frequency or wavelength, into various classes, frequency bands, frequency channels, etc. By way of example, the wireless communications system 100 may support one or multiple operating frequency bands, such as frequency range designations FR1 (410 MHz –7.125 GHz) , FR2 (24.25 GHz –52.6 GHz) , FR3 (7.125 GHz –24.25 GHz) , FR4 (52.6 GHz –114.25 GHz) , FR4a or FR4-1 (52.6 GHz –71 GHz) , and FR5 (114.25 GHz –300 GHz) . In some implementations, the network entities 102 and the UEs 104 may perform wireless communications over one or more of the operating frequency bands. In some implementations, FR1 may be used by the network entities 102 and the UEs 104, among other equipment or devices for cellular communications traffic (e.g., control information, data) . In some implementations, FR2 may be used by the network entities 102 and the UEs 104, among other equipment or devices for short-range, high data rate capabilities.

FR1 may be associated with one or multiple numerologies (e.g., at least three numerologies) . For example, FR1 may be associated with a first numerology (e.g., μ=0) , which includes 15 kHz subcarrier spacing; a second numerology (e.g., μ=1) , which includes 30 kHz subcarrier spacing; and a third numerology (e.g., μ=2) , which includes 60 kHz subcarrier spacing. FR2 may be associated with one or multiple numerologies (e.g., at least 2 numerologies) . For example, FR2 may be associated with a third numerology (e.g., μ=2) , which includes 60 kHz subcarrier spacing; and a fourth numerology (e.g., μ=3) , which includes 120 kHz subcarrier spacing.

Reference is now made to FIGS. 2A and 2B, which illustrate example process flows 200A and 200B in accordance with some example embodiments of the present disclosure. The process flows 200A and 200B may involve UEs 201 and 202, and a NE 203. The process flows 200A and 200B may be applied to the wireless communications system 100 with reference to FIG. 1. For example, the UEs 201 and 202 may be UEs 104, and the NE 203 may be a network entity 102. It would be appreciated that the process flows 200A and 200B may be applied to other communication scenarios, which will not be described in detail.

Reference is first made to FIG. 2A, the UE 201 determines (205) a slot for transmitting one or more sidelink reference signals. The slot may comprise one or more sidelink reference signal occasions. For example, the sidelink reference signal may comprise a CSI-RS. Alternatively or additionally, the sidelink reference signal may comprise any other types of sidelink reference signals, for example, for a purpose of beam management or any other purpose. The scope of the present disclosure is not limited in this regard.

The UE 201 transmits (210) , to the UE 202, the one or more sidelink reference signals in the slot. To facilitate beam management, one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals may comprise beam information for transmitting the one or more sidelink reference signals.

A slot structure of the slot may have a variety of forms, for example, depending on the number of the one or more sidelink reference signals to be transmitted, and/or depending on whether one beam or a plurality of beams may be used for transmitting the one or more sidelink reference signals. Some example slot structures will be discussed below.

Implementations where one sidelink reference signal is transmitted in the slot

In the time domain, only one sidelink reference signal may be transmitted in the slot. Thus, only one beam may be used to transmit the reference signal. Thus, a symbol (for example, only one symbol) for automatic gain control (AGC) (also referred to as an AGC symbol) may be needed.

Moreover, considering that for initial beam pairing purposes, some information may be needed to be carried in an SCI, for example, a source identifier (ID) of the UE 201, a destination ID (e.g., a default destination ID or ID of the UE 202) , possible resource reservation information about the periodic sidelink reference signal transmissions, and so on. Especially, a parameter of a beam index indicating the associated sidelink reference signal to be measured may be introduced in the SCI to distinguish between different TX beams of the UE 201. The parameter has a range of [0...N_tx, beam, ^max-1] , where N_tx, beam, ^max indicates the maximum number of TX beams, which, for example, may be determined per UE. The SCI may be carried in a PSCCH, which may occupy one or more symbols in the time domain (for example, two or three symbols are applied in NR V2X as specified in 3GPP Rel-16/Rel-17) . Therefore, at least one PSCCH symbol may be needed to carry the SCI.

In addition, if the reference signal is not transmitted on the PSCCH symbol (s) , at least one symbol may be needed to carry the reference signal. Moreover, the slot may also comprise one or more gap symbols.

In the frequency domain, a resource for transmission of the sidelink reference signal may be in units of sub-channels. Each sub-channel may consist of one or multiple consecutive PRBs. Each PRB within the sub-channel may use the same pattern for the sidelink reference signal. Within a block corresponding to one resource block in the frequency domain and one slot in the time domain, the resource mapping of the sidelink reference signal may be based on a CSI-RS resource mapping pattern in NR Uu.

In some embodiments, a plurality of sidelink slots may be located periodically in the time domain of a resource pool. Moreover, as an example, the sequence generation for the sidelink reference signal may reuse what is specified in NR sidelink Rel-16.

The following discussions are made with reference to FIGS. 3A and 3B to give examples. FIG. 3A illustrates a first example slot structure in accordance with some example embodiments of the present disclosure. As shown in FIG. 3A, this first example slot structure may not contain data and thus there is no data mapped to a symbol (s) for a PSCCH. The slot comprises an AGC symbol (i.e., symbol #0) , two PSCCH symbols (i.e., symbols #1 and 2) , a gap symbol, and a symbol for the SL CSI-RS. For example, as shown, any one of symbols 3 to 12 may be used to carry the SL CSI-RS.

FIG. 3B illustrates an example mapping pattern in accordance with some example embodiments of the present disclosure. For example, each PRB within the sub-channel as shown in FIG. 3A may use the same pattern as shown in FIG. 3B for the sidelink reference signal. As shown in FIG. 3B, resource elements (REs) with symbol #4 in the time domain and subcarriers #0, 4, and 8 in the frequency domain are used. It is to be understood that the mapping pattern as shown in FIG. 3B is only used as an example, and the reference signal may be mapped differently in other embodiments.

In view of the above considerations, in some embodiments, configuration information of the slot structure of the slot may comprise information on at least one of the following:

- an AGC symbol associated with the sidelink reference signal.

- one or more gap symbols.

- one or more PSCCH symbols occupied by the PSCCH that carry the SCI.

- one or more symbols carrying the sidelink reference signal. For example, a parameter referred to as “sl-CSI-RS-FirstSymbol” may be configured, which may indicate the first orthogonal frequency division multiplexing (OFDM) symbol in a PRB used for the SL CSI-RS.

- a frequency allocation of the sidelink reference signal, for example, indicating the number of antenna ports and the frequency domain allocation for the sidelink reference signal. For example, a parameter referred to as “sl-CSI-RS-FreqAllocation” may be configured, which may indicate the number of antenna ports and the frequency domain allocation for SL CSI-RS.

In some examples, if the resource pool enables a PSFCH, for the slot containing the PSFCH, the symbol (s) for the PSFCH may also be indicated in the slot structure. In addition, which slot (s) contains PSFCH may also be indicated in the resource pool.

In some examples, the configuration information may be pre-configured. In this case, the UE 201 and the UE 202 may determine the configuration of the slot structure based on the pre-configured information.

In some other examples, the configuration information may be configured by the NE 203. In this case, reference now is made to FIG. 2B. As shown in FIG. 2B, the NE 203 transmits (215) the configuration information to the UE 201 and transmits (220) the configuration information to the UE 202. Based on the configuration information obtained from the NE 203, the sidelink reference signal transmission between the UE 201 and the UE 202 may be performed. As an example, the configuration information may be configured via an MIB message. As another example, the configuration information may be configured via a SIB message. As a further example, the configuration information may be configured via a radio resource control (RRC) signaling. As yet a further example, the configuration information may be configured via a MAC CE. As still a further example, the configuration information may be configured via a DCI.

In some examples, the slot structure may be pre-configured or configured per resource pool. Alternatively or additionally, the slot structure may be pre-configured or configured per bandwidth part.

The above slot structure as discussed in these implementations is beneficial, as it has less impact on the legacy structure of SL CSI-RS carried in a PSSCH region of the slot.

Implementations where a plurality of sidelink reference signals are transmitted in the slot

Support for TX UE-side beam sweeping in the slot

To facilitate beam sweeping at the side of the UE 201, a plurality of sidelink reference signals may be transmitted by the UE 201 using a plurality of TX beams. The plurality of TX beams may be beamformed in different directions. The UE 202 may use one RX beam to measure the plurality of sidelink reference signals corresponding to the different TX beams from the UE 201. Therefore, In the time domain, an AGC symbol (for example, one AGC symbol) may be needed for each TX beam corresponding to a sidelink reference signal of the plurality of sidelink reference signals.

Moreover, similar information as described above may also be needed to accompany each sidelink reference signal. For each of the plurality of sidelink reference signals, such information may need to be included in an SCI. The SCI corresponding to each sidelink reference signal may be associated with a beam of the plurality of beams for transmitting the sidelink reference signal. Thus, a plurality of SCIs may be needed for the plurality of sidelink reference signals. Each SCI may be carried in a PSCCH, which may occupy at least one PSCCH symbol. Therefore, at least one PSCCH symbol may be needed for each associated sidelink reference signal.

To indicate the associations between beams and the sidelink reference signals, the plurality of SCIs may comprise beam information of the beams. For example, the plurality of SCIs may comprise a plurality of beam indexes for transmitting the plurality of sidelink reference signals. Each SCI may comprise a beam index for transmitting a respective sidelink reference signal.

In addition to the beam information, the plurality of SCIs may further comprise a number (or amount) of the plurality of sidelink reference signals. The number of the plurality of sidelink reference signals may be less than or equal to the total number of reference signal occasions within the slot. The total number of reference signal occasions within the slot may be obtained based on (pre-) configuration. Alternatively or additionally, the plurality of SCIs may further comprise a bitmap indicating the exact locations of the plurality of sidelink reference signals. As an example, considering multiple SL CSI-RS transmission occasions may be supported in the slot, a parameter N_CSI-RS ^Tx may indicate the number of SL CSI-RS to be transmitted within the slot, and the value of the parameter N_CSI-RS ^Tx may have a range of [1... N_CSI-RS ^slot] , where N_CSI-RS ^slot indicates the total number of SL CSI-RS occasions within the slot. Alternatively or additionally, a bitmap may be used to indicate the exact locations of SL CSI-RSs to be transmitted.

In addition, for each sidelink reference signal, if it is not transmitted on a symbol containing a PSCCH, at least one symbol may be needed to carry the sidelink reference signal. In this case, at least three symbols may be needed for each sidelink reference signal (or in other words, each associated TX beam) . If the sidelink reference signal is transmitted on a symbol containing a PSCCH, no additional symbol may be needed to carry the sidelink reference signal. In this case, at least two symbols may be needed for each sidelink reference signal.

In the frequency domain, the plurality of sidelink reference signals may have the same frequency allocation. Alternatively or additionally, the plurality of sidelink reference signals may have different frequency allocations.

The following discussions are made with reference to FIGS. 3C and 3G to give examples. FIG. 3C illustrates a second example slot structure in accordance with some example embodiments of the present disclosure. As shown in FIG. 3C, each slot contains 4 SL CSI-RSs, each of which is associated with 3 symbols, i.e., 1 AGC symbol, 1 PSCCH symbol carrying the SCI, and 1 SL CSI-RS symbol. The last two symbols are for gaps.

FIG. 3D illustrates a third example slot structure in accordance with some example embodiments of the present disclosure. As shown in FIG. 3D, each slot contains 4 SL CSI-RSs, each of which is associated with 3 symbols, i.e., 1 AGC symbol, 1 PSCCH symbol carrying the SCI, and 1 SL CSI-RS symbol. Different from FIG. 3C, in FIG. 3D, a gap symbol in the middle of the slot between adjacent SL CSI-RSs may serve as a transmission and reception switch, which is needed if the UE 201 is to transmit and receive SL CSI-RSs within the slot. In this case, symbol #6 is a gap between two SL CSI-RSs.

FIG. 3E illustrates a fourth example slot structure in accordance with some example embodiments of the present disclosure. As shown in FIG. 3E, each slot contains 3 SL CSI-RSs, each of the first two of which is associated with 4 symbols, i.e., 1 AGC symbol, 2 PSCCH symbols carrying the SCI, and 1 SL CSI-RS symbol. The two-symbol SCI is used to decrease the frequency-domain resource consumed. In the frequency domain, the SCI may occupy a (pre-) configurable number of PRBs per resource pool (for example, 10, 12, 15, 20, or 25 PRBs) . For example, it is assumed that the payload size for the SCI is 20 PRBs. If one PSCCH symbol is applied, the frequency-domain resource for the SL CSI-RS transmission spans at least 20 PRBs. If two PSCCH symbols are applied, the frequency-domain resource for the SL CSI-RS transmission spans as low as 10 PRBs. In addition, As shown in FIG. 3E, multiple SL CSI-RSs within the slot may have different different frequency allocations. For example, the first two SL CSI-RSs in the slot occupy only one symbol, while the third SL CSI-RS occupies two symbols.

FIG. 3F illustrates a fifth example slot structure in accordance with some example embodiments of the present disclosure. As shown in FIG. 3F, a SL CSI-RS and a PSCCH are frequency division multiplexed (FDMed) within the symbol. In this case, the PSCCH is first mapped from the lowest PRBs of a symbol for both the PSCCH and the SL CSI-RS. Then, the SL CSI-RS is mapped from the end PRB for the PSCCH to the end of the only one sub-channel or the last sub-channel (if the resources for the SL CSI-RS span multiple sub-channels) .

FIG. 3G illustrates a sixth example slot structure in accordance with some example embodiments of the present disclosure. In this case, SL CSI-RS transmissions accompany a physical sidelink feedback channel (PSFCH) transmission within the slot. At least three symbols are needed for the PSFCH transmission, including one gap symbol, one AGC symbol, and one PSFCH symbol. As shown in FIG. 3G, within the slot, the first 10 symbols are used for SL CSI-RSs. Then the succeeding 3 symbols are used for the PSFCH transmission. The last symbol within the slot serves as a gap.

- a plurality of automatic gain control (AGC) symbols associated with the plurality of sidelink reference signals. Each of the plurality of AGC symbols may correspond to one sidelink reference signal. As an example, to avoid the AGC issue, the slot structure applied in the same slot may be identical.

- one or more gap symbols.

- a plurality of PSCCH symbols carrying the plurality of SCIs. Each of the SCIs may correspond to one sidelink reference signal.

- a plurality of symbols carrying the plurality of sidelink reference signals. For example, a set of parameters “sl-CSI-RS-FirstSymbol” may be configured to indicate the first OFDM symbols in a PRB used for a set of SL CSI-RSs within the slot, respectively. As an example, the set of first OFDM symbols as shown in FIG. 3C corresponds to symbols #2, #5, #8, #11.

- one or more frequency allocations of the one or more sidelink reference signals. For example, if the number of antenna ports and the frequency domain allocation are identical for all sidelink reference signals, then only one frequency allocation parameter (for example, referred to as “sl-CSI-RS-FreqAllocation” ) may be needed. Otherwise, a set of frequency allocation parameters may be needed. For example, whether the plurality of sidelink reference signals use the same frequency allocation or not may be indicated by the number of frequency allocations in the configuration information of the slot. Alternatively or additionally, a new frequency allocation indicator may be used to indicate whether the one or more sidelink reference signals follow an identical frequency allocation. For example, the new indicator may be denoted as sl-CSI-RS-Identical, which may be a boolean value

- a PSFCH symbol if any.

More details as described above when discussing the implementations where one sidelink reference signal is transmitted in the slot may also apply. For the purpose of simplification, the details will be omitted.

Support for RX UE-side beam sweeping in the slot

To facilitate beam sweeping at the side of the UE 202, the UE 202 may use different RX beams to measure the plurality of sidelink reference signals corresponding to the same TX beam from the UE 201. In this case, in the time domain, an AGC symbol (for example, only one AGC symbol) may be needed for the same TX beam within one slot.

Similar to AGC, an SCI (for example, only one SCI) may be needed for the plurality of sidelink reference signals within the slot. Therefore, at least one PSCCH symbol may be needed for the associated sidelink reference signals. As an example, the beam information comprised in the SCI may comprise a parameter indicating whether the same beam is used for transmitting the plurality of sidelink reference signals. In this case, a new parameter may be introduced to indicate whether the UE 201 repeats the same TX beam in the current slot. For example, the parameter may be denoted by “repetition” . If the parameter of “repetition” is configured or is set to “on” , the UE 202 may assume the UE 201 transmits all the sidelink reference signals within the slot using the same TX beam to enable the UE 201 to perform RX beam sweeping. Otherwise, when the parameter “repetition” is not configured or is set to “off” , the UE 202 may assume the UE 201 transmits the sidelink reference signals using different TX beams.

The following discussions are made with reference to FIGS. 3H and 3J to give examples, where FIG. 3H illustrates a seventh example slot structure in accordance with some example embodiments of the present disclosure, and FIG. 3I illustrates an eighth example slot structure in accordance with some example embodiments of the present disclosure. As shown in FIGS. 3H and 3I, except the first two symbols (i.e. one AGC symbol and one PSCCH symbol) , all the remaining symbols, except the last one for a gap, are used for SL CSI-RS transmissions. If each SL CSI-RS occupies one symbol, up to 11 SL CSI-RSs are supported by the seventh example slot structure as illustrated in FIG. 3H. If each SL CSI-RS occupies two symbols, up to 5 CSI-RS are supported by the eighth example slot structure as illustrated in FIG. 3I.

FIG. 3J illustrates a ninth example slot structure in accordance with some example embodiments of the present disclosure. In this case, SL CSI-RS transmissions accompany a PSFCH transmission within the slot. For example, different from FIG. 3H, at least three symbols are needed for the PSFCH transmission, including one gap symbol, one AGC symbol, and one PSFCH symbol.

- an automatic gain control (AGC) symbol.

- one or more gap symbols.

- at least one PSCCH symbol carrying the SCI.

- a plurality of symbols carrying the plurality of sidelink reference signals.

- one or more frequency allocations of the one or more sidelink reference signals.

More details as described above when discussing the implementations where one sidelink reference signal is transmitted in the slot and the embodiments for support for TX UE-side beam sweeping may also apply. For the purpose of simplification, the details will be omitted.

In some examples, to distinguish the slot structures for the support for TX UE-side beam sweeping and for the support for RX UE-side beam sweeping, a variety of approaches may be applied. For the purpose of simplification, a slot structure for the support for TX UE-side beam sweeping may be referred to as a first slot structure, and a slot structure for the support for RX UE-side beam sweeping may be referred to as a second slot structure.

In some embodiments, only one of the first slot structure or the second slot structure may be pre-configured or configured for a resource pool in which the slot is in. In other words, only one of the first slot structure or the second slot structure may be pre-configured or configured per resource pool. In this case, only one slot structure may be supported for one resource pool at a time. Which slot structure is supported may be pre-configured or configured by the NE 203, for example, via an RRC signaling.

In some other embodiments, both the first slot structure and the second slot structure may be pre-configured or configured for a resource pool in which the slot is in. For example, a bitmap may be used to indicate whether the first slot structure or the second slot structure is applied for each of a plurality of slots within the resource pool. As an example, the value of 1 may represent the first slot structure, and the value of 0 may represent the second slot structure. For example, the bitmap may be comprised in the above configuration information.

In some further embodiments where both the first slot structure and the second slot structure are pre-configured or configured for a resource pool, some further information, such as periodicity information or slot offset information may be pre-configured or configured, for example, in the above configuration information. For example, a first periodicity and a second periodicity may be pre-configured or configured for the first slot structure and the second slot structure respectively, where the first periodicity indicates a distribution of the first slot structure in the resource pool and the second periodicity indicates a distribution of the second slot structure in the resource pool. As another example, a first slot offset and a second slot offset may be pre-configured or configured for the first slot structure and the second slot structure respectively, where the first slot offset indicates a distribution of the first slot structure in the resource pool and the second slot offset indicates a distribution of the second slot structure in the resource pool.

According to some embodiments with reference to FIGS. 2 to 3J, by transmitting one or more sidelink reference signals in the slot, it is allowed to improve spectrum efficiency for sidelink reference signal transmissions, and by comprising beam information in the one or more SCIs, it is allowed to facilitate TX beam sweeping and RX beam sweeping. In this way, it is possible to improve the sidelink communications with enhanced efficiency.

FIG. 4 illustrates an example of a device 400 that supports a sidelink reference signal framework in accordance with aspects of the present disclosure. The device 400 may be an example of a UE 104 or a network entity 102 as described herein. The device 400 may support wireless communication with one or more network entities 102, UEs 104, or any combination thereof. The device 400 may include components for bi-directional communications including components for transmitting and receiving communications, such as a processor 402, a memory 404, a transceiver 406, and, optionally, an I/O controller 408. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 402, the memory 404, the transceiver 406, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure as described herein. For example, the processor 402, the memory 404, the transceiver 406, or various combinations or components thereof may support a method for performing one or more of the operations described herein.

In some implementations, the processor 402, the memory 404, the transceiver 406, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry) . The hardware may include a processor, a digital signal processor (DSP) , an application-specific integrated circuit (ASIC) , a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure. In some implementations, the processor 402 and the memory 404 coupled with the processor 402 may be configured to perform one or more of the functions described herein (e.g., executing, by the processor 402, instructions stored in the memory 404) .

For example, the processor 402 may support wireless communication at the device 400 in accordance with examples as disclosed herein. The processor 402 may be configured to operable to support a means for determining a slot for transmitting one or more sidelink reference signals; and a means for transmitting the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals. The processor 402 may be configured to operable to support a means for transmitting, to a user equipment (UE) , configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

The processor 402 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some implementations, the processor 402 may be configured to operate a memory array using a memory controller. In some other implementations, a memory controller may be integrated into the processor 402. The processor 402 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 404) to cause the device 400 to perform various functions of the present disclosure.

The memory 404 may include random access memory (RAM) and read-only memory (ROM) . The memory 404 may store computer-readable, computer-executable code including instructions that, when executed by the processor 402 cause the device 400 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some implementations, the code may not be directly executable by the processor 402 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some implementations, the memory 404 may include, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The I/O controller 408 may manage input and output signals for the device 400. The I/O controller 408 may also manage peripherals not integrated into the device M02. In some implementations, the I/O controller 408 may represent a physical connection or port to an external peripheral. In some implementations, the I/O controller 408 may utilize an operating system such as or another known operating system. In some implementations, the I/O controller 408 may be implemented as part of a processor, such as the processor 406. In some implementations, a user may interact with the device 400 via the I/O controller 408 or via hardware components controlled by the I/O controller 408.

In some implementations, the device 400 may include a single antenna 410. However, in some other implementations, the device 400 may have more than one antenna 410 (i.e., multiple antennas) , including multiple antenna panels or antenna arrays, which may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 406 may communicate bi-directionally, via the one or more antennas 410, wired, or wireless links as described herein. For example, the transceiver 406 may represent a wireless transceiver and may communicate bi- directionally with another wireless transceiver. The transceiver 406 may also include a modem to modulate the packets, to provide the modulated packets to one or more antennas 410 for transmission, and to demodulate packets received from the one or more antennas 410. The transceiver 406 may include one or more transmit chains, one or more receive chains, or a combination thereof.

A transmit chain may be configured to generate and transmit signals (e.g., control information, data, packets) . The transmit chain may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM) , frequency modulation (FM) , or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM) . The transmit chain may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmit chain may also include one or more antennas 410 for transmitting the amplified signal into the air or wireless medium.

A receive chain may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receive chain may include one or more antennas 410 for receive the signal over the air or wireless medium. The receive chain may include at least one amplifier (e.g., a low-noise amplifier (LNA) ) configured to amplify the received signal. The receive chain may include at least one demodulator configured to demodulate the receive signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receive chain may include at least one decoder for decoding the processing the demodulated signal to receive the transmitted data.

FIG. 5 illustrates an example of a processor 500 that supports a sidelink reference signal framework in accordance with aspects of the present disclosure. The processor 500 may be an example of a processor configured to perform various operations in accordance with examples as described herein. The processor 500 may include a controller 502 configured to perform various operations in accordance with examples as described herein. The processor 500 may optionally include at least one memory 504, such as L1/L2/L3 cache. Additionally, or alternatively, the processor 500 may optionally include one or more arithmetic-logic units (ALUs) 500. One or more of these components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses) .

The processor 500 may be a processor chipset and include a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) in accordance with examples as described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory local to or included in the processor chipset (e.g., the processor 500) or other memory (e.g., random access memory (RAM) , read-only memory (ROM) , dynamic RAM (DRAM) , synchronous dynamic RAM (SDRAM) , static RAM (SRAM) , ferroelectric RAM (FeRAM) , magnetic RAM (MRAM) , resistive RAM (RRAM) , flash memory, phase change memory (PCM) , and others) .

The controller 502 may be configured to manage and coordinate various operations (e.g., signaling, receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) of the processor 500 to cause the processor 500 to support various operations in accordance with examples as described herein. For example, the controller 502 may operate as a control unit of the processor 500, generating control signals that manage the operation of various components of the processor 500. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating timing of operations.

The controller 502 may be configured to fetch (e.g., obtain, retrieve, receive) instructions from the memory 504 and determine subsequent instruction (s) to be executed to cause the processor 500 to support various operations in accordance with examples as described herein. The controller 502 may be configured to track memory address of instructions associated with the memory 504. The controller 502 may be configured to decode instructions to determine the operation to be performed and the operands involved. For example, the controller 502 may be configured to interpret the instruction and determine control signals to be output to other components of the processor 500 to cause the processor 500 to support various operations in accordance with examples as described herein. Additionally, or alternatively, the controller 502 may be configured to manage flow of data within the processor 500. The controller 502 may be configured to control transfer of data between registers, arithmetic logic units (ALUs) , and other functional units of the processor 500.

The memory 504 may include one or more caches (e.g., memory local to or included in the processor 500 or other memory, such RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementations, the memory 504 may reside within or on a processor chipset (e.g., local to the processor 500) . In some other implementations, the memory 504 may reside external to the processor chipset (e.g., remote to the processor 500) .

The memory 504 may store computer-readable, computer-executable code including instructions that, when executed by the processor 500, cause the processor 500 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. The controller 502 and/or the processor 500 may be configured to execute computer-readable instructions stored in the memory 504 to cause the processor 500 to perform various functions. For example, the processor 500 and/or the controller 502 may be coupled with or to the memory 504, and the processor 500, the controller 502, and the memory 504 may be configured to perform various functions described herein. In some examples, the processor 500 may include multiple processors and the memory 504 may include multiple memories. One or more of the multiple processors may be coupled with one or more of the multiple memories, which may, individually or collectively, be configured to perform various functions herein.

The one or more ALUs 500 may be configured to support various operations in accordance with examples as described herein. In some implementations, the one or more ALUs 500 may reside within or on a processor chipset (e.g., the processor 500) . In some other implementations, the one or more ALUs 500 may reside external to the processor chipset (e.g., the processor 500) . One or more ALUs 500 may perform one or more computations such as addition, subtraction, multiplication, and division on data. For example, one or more ALUs 500 may receive input operands and an operation code, which determines an operation to be executed. One or more ALUs 500 be configured with a variety of logical and arithmetic circuits, including adders, subtractors, shifters, and logic gates, to process and manipulate the data according to the operation. Additionally, or alternatively, the one or more ALUs 500 may support logical operations such as AND, OR, exclusive-OR (XOR) , not-OR (NOR) , and not-AND (NAND) , enabling the one or more ALUs 500 to handle conditional operations, comparisons, and bitwise operations.

The processor 500 may support wireless communication in accordance with examples as disclosed herein. The processor 500 may be configured to or operable to support a means for determining a slot for transmitting one or more sidelink reference signals; and a means for transmitting the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals. The processor 500 may be configured to or operable to support a means for transmitting, to a user equipment (UE) , configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.

FIG. 6 illustrates a flowchart of a method 600 that supports a sidelink reference signal framework in accordance with aspects of the present disclosure. The operations of the method 600 may be implemented by a device or its components as described herein. For example, the operations of the method 600 may be performed by a UE 201 as described herein. In some implementations, the device may execute a set of instructions to control the function elements of the device to perform the described functions. Additionally, or alternatively, the device may perform aspects of the described functions using special-purpose hardware.

At 610, the method may include determining a slot for transmitting one or more sidelink reference signals. The operations of 610 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 610 may be performed by a UE 201 as described with reference to FIG. 2A.

At 620, the method may include transmitting the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals. The operations of 620 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 620 may be performed by a UE 201 as described with reference to FIG. 2A.

In some implementations, configuration information of a slot structure of the slot comprises information on one of the following: one or more automatic gain control (AGC) symbols associated with the one or more sidelink reference signals; one or more gap symbols; one or more physical sidelink control channel (PSCCH) symbols carrying the one or more SCIs; one or more symbols carrying the one or more sidelink reference signals; or one or more frequency allocations of the one or more sidelink reference signals.

In some implementations, the configuration information is configured by a network equipment or pre-configured.

In some implementations, the configuration information is configured via one of the following: a master information block (MIB) message; a system information block (SIB) message; a radio resource control (RRC) signaling; a medium access control (MAC) control element (CE) ; or downlink control information (DCI) .

In some implementations, the slot structure is pre-configured or configured per resource pool or per bandwidth part.

In some implementations, the one or more sidelink reference signals comprise a plurality of sidelink reference signals, and the slot structure comprises one of the following: a first slot structure, in which a plurality of beams are used for transmitting the plurality of sidelink reference signals, and wherein the one or more SCIs comprise a plurality of SCIs, and the slot comprises a plurality of ACG symbols and a plurality of PSCCH symbols, an ACG symbol of the plurality of ACG symbols and a PSCCH symbol of the plurality of PSCCH symbols correspond to a sidelink reference signal of the plurality of sidelink reference signals, a beam of the plurality of beams being associated with an SCI of the plurality of SCIs carried in a PSCCH symbol of the plurality of PSCCH symbols; or a second slot structure, in which a same beam is used for transmitting the plurality of sidelink reference signals and wherein the one or more SCIs comprise one SCI, and the slot comprises an ACG symbol and a PSCCH symbol, the ACG symbol and the PSCCH symbol corresponding to the plurality of sidelink reference signals, the same beam being associated with the one SCI carried in the PSCCH symbol.

In some implementations, one of the first slot structure or the second slot structure is pre-configured or configured for a resource pool in which the slot is in.

In some implementations, the first slot structure and the second slot structure are pre-configured or configured for a resource pool in which the slot is in, and the configuration information further comprises a bitmap indicating whether the first slot structure or the second slot structure is applied for each of a plurality of slots within the resource pool.

In some implementations, the first slot structure and the second slot structure are pre-configured or configured for a resource pool in which the slot is in, and the configuration information further comprises one of the following: a first periodicity and a second periodicity, the first periodicity indicating a distribution of the first slot structure in the resource pool and the second periodicity indicating a distribution of the second slot structure in the resource pool; or a first slot offset and a second slot offset, the first slot offset indicating a distribution of the first slot structure in the resource pool and the second slot offset indicating a distribution of the second slot structure in the resource pool.

In some implementations, the configuration information comprises information on the one or more frequency allocations of the one or more sidelink reference signals, and whether the one or more sidelink reference signals use a same frequency allocation or not is indicated by one of the following: a number of frequency allocations in the configuration information of the slot; or a frequency allocation indicator to indicate whether the one or more sidelink reference signals use a same frequency allocation or not.

In some implementations, the beam information comprises one of the following: one or more beam indexes for transmitting the one or more sidelink reference signals; or a parameter indicating whether a same beam is used for transmitting the one or more sidelink reference signals.

In some implementations, the one or more SCIs further comprises one of the following: a number of the one or more sidelink reference signals, the number of the one or more sidelink reference signals being less than or equal to a total number of reference signal occasions within the slot; or a bitmap indicating one or more locations of the one or more sidelink reference signals.

FIG. 7 illustrates a flowchart of a method 700 that supports a sidelink reference signal framework in accordance with aspects of the present disclosure. The operations of the method 700 may be implemented by a device or its components as described herein. For example, the operations of the method 700 may be performed by an NE 203 as described herein. In some implementations, the device may execute a set of instructions to control the function elements of the device to perform the described functions. Additionally, or alternatively, the device may perform aspects of the described functions using special-purpose hardware.

At 710, the method may include transmitting, to a user equipment (UE) , configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals. The operations of 710 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 710 may be performed by an NE 203 as described with reference to FIG. 2B.

In some implementations, the configuration information comprises information on one of the following: one or more automatic gain control (AGC) symbols associated with the one or more sidelink reference signals; one or more gap symbols; one or more physical sidelink control channel (PSCCH) symbols carrying the one or more SCIs; one or more symbols carrying the one or more sidelink reference signals; or one or more frequency allocations of the one or more sidelink reference signals.

In some implementations, the configuration information is transmitted via one of the following: a master information block (MIB) message; a system information block (SIB) message; a radio resource control (RRC) signaling; a medium access control (MAC) control element (CE) ; or downlink control information (DCI) .

In some implementations, the slot structure is configured per resource pool or per bandwidth part.

In some implementations, one of the first slot structure or the second slot structure is configured for a resource pool in which the slot is in.

In some implementations, the first slot structure and the second slot structure are configured for a resource pool in which the slot is in, and the configuration information further comprises a bitmap indicating whether the first slot structure or the second slot structure is applied for each of a plurality of slots within the resource pool.

In some implementations, the first slot structure and the second slot structure are configured for a resource pool in which the slot is in, and the configuration information further comprises one of the following: a first periodicity and a second periodicity, the first periodicity indicating a distribution of the first slot structure in the resource pool and the second periodicity indicating a distribution of the second slot structure in the resource pool; or a first slot offset and a second slot offset, the first slot offset indicating a distribution of the first slot structure in the resource pool and the second slot offset indicating a distribution of the second slot structure in the resource pool.

It should be noted that the methods described herein describes possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer. By way of example, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

As used herein, including in the claims, an article “a” before an element is unrestricted and understood to refer to “at least one” of those elements or “one or more” of those elements. The terms “a, ” “at least one, ” “one or more, ” and “at least one of one or more” may be interchangeable. As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” or “one or both of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. Further, as used herein, including in the claims, a “set” may include one or more elements.

The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A user equipment (UE) comprising:

at least one memory; and

at least one processor coupled with the at least one memory and configured to cause the UE to:

determine a slot for transmitting one or more sidelink reference signals; and

transmit the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.
The UE of claim 1, wherein configuration information of a slot structure of the slot comprises information on one of the following:

one or more automatic gain control (AGC) symbols associated with the one or more sidelink reference signals;

one or more gap symbols;

one or more physical sidelink control channel (PSCCH) symbols carrying the one or more SCIs;

one or more symbols carrying the one or more sidelink reference signals; or

one or more frequency allocations of the one or more sidelink reference signals.
The UE of claim 2, wherein the configuration information is configured by a network equipment or pre-configured.
The UE of claim 2, wherein the configuration information is configured via one of the following:

a master information block (MIB) message;

a system information block (SIB) message;

a radio resource control (RRC) signaling;

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

downlink control information (DCI) .
The UE of claim 2, wherein the slot structure is pre-configured or configured per resource pool or per bandwidth part.
The UE of claim 2, wherein the one or more sidelink reference signals comprise a plurality of sidelink reference signals, and the slot structure comprises one of the following:

a first slot structure, in which a plurality of beams are used for transmitting the plurality of sidelink reference signals, and wherein the one or more SCIs comprise a plurality of SCIs, and the slot comprises a plurality of ACG symbols and a plurality of PSCCH symbols, an ACG symbol of the plurality of ACG symbols and a PSCCH symbol of the plurality of PSCCH symbols correspond to a sidelink reference signal of the plurality of sidelink reference signals, a beam of the plurality of beams being associated with an SCI of the plurality of SCIs carried in a PSCCH symbol of the plurality of PSCCH symbols; or

a second slot structure, in which a same beam is used for transmitting the plurality of sidelink reference signals and wherein the one or more SCIs comprise one SCI, and the slot comprises an ACG symbol and a PSCCH symbol, the ACG symbol and the PSCCH symbol corresponding to the plurality of sidelink reference signals, the same beam being associated with the one SCI carried in the PSCCH symbol.
The UE of claim 6, wherein one of the first slot structure or the second slot structure is pre-configured or configured for a resource pool in which the slot is in.
The UE of claim 6, wherein the first slot structure and the second slot structure are pre-configured or configured for a resource pool in which the slot is in, and the configuration information further comprises a bitmap indicating whether the first slot structure or the second slot structure is applied for each of a plurality of slots within the resource pool.
The UE of claim 6, wherein the first slot structure and the second slot structure are pre-configured or configured for a resource pool in which the slot is in, and the configuration information further comprises one of the following:

a first periodicity and a second periodicity, the first periodicity indicating a distribution of the first slot structure in the resource pool and the second periodicity indicating a distribution of the second slot structure in the resource pool; or

a first slot offset and a second slot offset, the first slot offset indicating a distribution of the first slot structure in the resource pool and the second slot offset indicating a distribution of the second slot structure in the resource pool.
The UE of claim 2, wherein the configuration information comprises information on the one or more frequency allocations of the one or more sidelink reference signals, and whether the one or more sidelink reference signals use a same frequency allocation or not is indicated by one of the following:

a number of frequency allocations in the configuration information of the slot; or

a frequency allocation indicator to indicate whether the one or more sidelink reference signals use a same frequency allocation or not.
The UE of claim 1, wherein the beam information comprises one of the following:

one or more beam indexes for transmitting the one or more sidelink reference signals; or

a parameter indicating whether a same beam is used for transmitting the one or more sidelink reference signals.
The UE of claim 1, wherein the one or more SCIs further comprises one of the following:

a number of the one or more sidelink reference signals, the number of the one or more sidelink reference signals being less than or equal to a total number of reference signal occasions within the slot; or

a bitmap indicating one or more locations of the one or more sidelink reference signals.
A network equipment (NE) comprising:

at least one memory; and

at least one processor coupled with the at least one memory and configured to cause the NE to:

transmit, to a user equipment (UE) , configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.
The NE of claim 13, wherein the configuration information comprises information on one of the following:

one or more automatic gain control (AGC) symbols associated with the one or more sidelink reference signals;

one or more gap symbols;

one or more physical sidelink control channel (PSCCH) symbols carrying the one or more SCIs;

one or more symbols carrying the one or more sidelink reference signals; or

one or more frequency allocations of the one or more sidelink reference signals.
The NE of claim 13, wherein the configuration information is transmitted via one of the following:

a master information block (MIB) message;

a system information block (SIB) message;

a radio resource control (RRC) signaling;

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

downlink control information (DCI) .
The NE of claim 13, wherein the slot structure is configured per resource pool or per bandwidth part.
The NE of claim 13, wherein the one or more sidelink reference signals comprise a plurality of sidelink reference signals, and the slot structure comprises one of the following:

a first slot structure, in which a plurality of beams are used for transmitting the plurality of sidelink reference signals, and wherein the one or more SCIs comprise a plurality of SCIs, and the slot comprises a plurality of ACG symbols and a plurality of PSCCH symbols, an ACG symbol of the plurality of ACG symbols and a PSCCH symbol of the plurality of PSCCH symbols correspond to a sidelink reference signal of the plurality of sidelink reference signals, a beam of the plurality of beams being associated with an SCI of the plurality of SCIs carried in a PSCCH symbol of the plurality of PSCCH symbols; or

a second slot structure, in which a same beam is used for transmitting the plurality of sidelink reference signals and wherein the one or more SCIs comprise one SCI, and the slot comprises an ACG symbol and a PSCCH symbol, the ACG symbol and the PSCCH symbol corresponding to the plurality of sidelink reference signals, the same beam being associated with the one SCI carried in the PSCCH symbol.
The NE of claim 17, wherein one of the first slot structure or the second slot structure is configured for a resource pool in which the slot is in.
A method performed by a user equipment (UE) , comprising:

determining a slot for transmitting one or more sidelink reference signals; and

transmitting the one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.
A method performed by a network equipment (NE) , comprising:

transmitting, to a user equipment (UE) , configuration information of a slot structure of a slot, for the UE to transmit one or more sidelink reference signals in the slot, wherein one or more sidelink control information (SCIs) associated with the one or more sidelink reference signals comprise beam information for transmitting the one or more sidelink reference signals.