Demodulation reference signal (DMRS) transmission for lateral link communications

Abstract

Techniques for wireless communication are disclosed. In one aspect, a transmitter user equipment (UE) determines a first demodulation reference signal (DMRS) pattern for a first time slot allocated for transmission on a lateral link between the transmitter UE and a receiver UE, where the first DMRS pattern is determined based at least on the first time slot having a first slot format of two or more slot formats, and where the first DMRS pattern is determined based on the first slot format of the two or more slot formats. And transmitting the DMRS to the receiver UE in the first time slot according to the first DMRS mode. In one aspect, a receiver UE determines a first DMRS pattern for a first time slot based at least on the first time slot having a first time slot format, and receives a DMRS from a transmitter UE in the first time slot according to the first DMRS pattern.

Description

[0001] This application is a divisional application of a Chinese patent application filed on October 5, 2020, with application number 202080068025.9, and invention name “Demodulation Reference Signal (DMRS) Transmission for Sidelink Communication”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims the benefit of U.S. Provisional Application No. 62 / 910,894, filed on October 4, 2019, entitled “DEMODULATION REFERENCE SIGNAL (DMRS) TRANSMISSION FOR SIDELINK COMMUNICATIONS,” and U.S. Non-Provisional Application No. 17 / 061,932, filed on October 2, 2020, entitled “DEMODULATION REFERENCE SIGNAL (DMRS) TRANSMISSION FOR SIDELINK COMMUNICATIONS,” both of which have been assigned to the assignee of this application, and their entire contents are expressly incorporated herein by reference. Technical Field

[0004]

[0013] Generally speaking, aspects of the present disclosure relate to wireless communications. Background Art

[0005] Wireless communication systems have evolved over many generations, including first generation analog wireless telephone service (1G), second generation (2G) digital wireless telephone service (including intermediate 2.5G networks), third generation (3G) high speed data, Internet enabled wireless service, and fourth generation (4G) service (e.g., LTE or WiMax). There are many different types of wireless communication systems in use today, including cellular and personal communications service (PCS) systems. Examples of known cellular systems include the cellular analog Advanced Mobile Phone System (AMPS) and digital cellular systems based on code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile Communications (GSM), and the like.

[0006] The fifth generation (5G) wireless standard is called New Radio (NR), which enables higher data transmission speeds, more connections, and better coverage, among other improvements. According to the Next Generation Mobile Network Alliance, the NR standard is designed to provide data rates of tens of megabits per second to tens of thousands of users and 1 gigabit per second to dozens of employees in an office building. Hundreds of thousands of simultaneous connections should be supported to support large wireless sensor deployments. Therefore, the spectral efficiency of NR mobile communications should be significantly improved compared to the current 4G standard. In addition, signaling efficiency should be improved and latency should be significantly reduced compared to the current standard. Summary of the invention

[0007] A brief summary of one or more aspects disclosed herein is provided below. Therefore, the following summary section should not be interpreted as an exhaustive overview of all contemplated aspects, nor should the following summary section be interpreted as identifying key or important elements related to all contemplated aspects, or describing the scope associated with any particular aspect. Therefore, the sole purpose of the following summary section is to present certain concepts related to one or more aspects related to the mechanisms disclosed herein in a simple form as a prelude to the detailed description below.

[0008] In one aspect, a method for wireless communication performed by a transmitter user equipment (UE) includes: determining a first demodulation reference signal (DMRS) pattern for a first time slot, the first time slot being allocated for transmission on a side link between the transmitter UE and a receiver UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, and wherein the first time slot format specifies at least a first number of orthogonal frequency division multiplexing (OFDM) symbols that can be used for side link transmission; and sending the DMRS to the receiver UE in the first time slot according to the first DMRS pattern.

[0009] In one aspect, a method for wireless communication performed by a receiver UE includes: determining a first DMRS pattern for a first time slot, the first time slot being allocated for data reception on a side link between the receiver UE and a transmitter UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, and wherein the first time slot format specifies at least a first number of OFDM symbols that can be used for side link transmission; and receiving a DMRS from the transmitter UE in the first time slot according to the first DMRS pattern.

[0010] In one aspect, a transmitter UE includes a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor being configured to: determine a first DMRS pattern for a first time slot, the first time slot being allocated for transmission on a side link between the transmitter UE and a receiver UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, and wherein the first time slot format specifies at least a first number of OFDM symbols available for side link transmission; and cause the at least one transceiver to send a DMRS to the receiver UE in the first time slot according to the first DMRS pattern.

[0011] In one aspect, a receiver UE includes a memory; at least one transceiver; and at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor being configured to: determine a first DMRS pattern for a first time slot, the first time slot being allocated for data reception on a side link between the receiver UE and a transmitter UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, and wherein the first time slot format specifies at least a first number of OFDM symbols that can be used for side link transmission; and receive a DMRS from the transmitter UE in the first time slot via the at least one transceiver according to the first DMRS pattern.

[0012] In one aspect, a transmitter UE includes: a unit for determining a first DMRS pattern for a first time slot, the first time slot being allocated for transmission on a side link between the transmitter UE and a receiver UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format among two or more time slot formats, and wherein the first time slot format specifies at least a first number of OFDM symbols available for side link transmission; and a unit for sending a DMRS to the receiver UE in the first time slot according to the first DMRS pattern.

[0013] In one aspect, a receiver UE includes: a unit for determining a first DMRS pattern for a first time slot, the first time slot being allocated for data reception on a side link between the receiver UE and a transmitter UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, and wherein the first time slot format specifies at least a first number of OFDM symbols that can be used for side link transmission; and a unit for receiving a DMRS from the transmitter UE in the first time slot according to the first DMRS pattern.

[0014] In one aspect, a non-temporary computer-readable medium storing computer-executable instructions includes computer-executable instructions for performing the following operations: at least one instruction for instructing a transmitter UE to determine a first DMRS pattern for a first time slot, the first time slot being allocated for transmission on a side link between the transmitter UE and a receiver UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, and wherein the first time slot format specifies at least a first number of orthogonal frequency division multiplexing (OFDM) symbols that can be used for side link transmission; and at least one instruction for instructing the transmitter UE to send a DMRS to the receiver UE in the first time slot according to the first DMRS pattern.

[0015] In one aspect, a non-transitory computer-readable medium storing computer-executable instructions includes computer-executable instructions for performing the following operations: at least one instruction for instructing a receiver UE to determine a first DMRS pattern for a first time slot, the first time slot being allocated for data reception on a side link between the receiver UE and a transmitter UE, wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, and wherein the first time slot format specifies at least a first number of orthogonal frequency division multiplexing (OFDM) symbols that can be used for side link transmission; and at least one instruction for instructing the receiver UE to receive DMRS from the transmitter UE in the first time slot according to the first DMRS pattern.

[0016] Other objects and advantages associated with the various aspects disclosed herein will be apparent to one of ordinary skill in the art based on the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are presented to aid in describing various aspects of the disclosure and are provided solely for the purpose of depicting these aspects and not limiting thereof.

[0018] Figure 1 In accordance with various aspects of the present disclosure, an exemplary wireless communication system is shown.

[0019] Figure 2A and Figure 2B In accordance with various aspects of the present disclosure, exemplary wireless network structures are shown.

[0020] Figure 3 According to various aspects of the present disclosure, an example of a wireless communication system that supports unicast sidelink establishment is shown.

[0021] Figure 4 is a block diagram illustrating an exemplary UE according to various aspects of the present disclosure.

[0022] Figure 5 is a diagram illustrating an example of a frame structure used in a wireless telecommunication system in accordance with various aspects of the present disclosure.

[0023] Figures 6 to 10 Exemplary demodulation reference signal (DMRS) patterns are shown in accordance with various aspects of the present disclosure.

[0024] Fig.11 and Fig.12

[0013] Example methods of wireless communications in accordance with aspects of the present disclosure are shown. DETAILED DESCRIPTION

[0025] In the following description and the related drawings of the specific examples directed to the disclosed subject matter, various aspects of the present disclosure are provided. Without departing from the protection scope of the disclosed subject matter, alternative aspects can be designed. In addition, in order to avoid causing the ambiguity of the relevant details of the present disclosure, some well-known elements are not described in detail or are omitted.

[0026] As used herein, the words "exemplary" and / or "example" mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" and / or "example" should not be construed as preferred or advantageous over other aspects. Likewise, the term "aspects of the disclosure" does not require that all aspects of the disclosure include the discussed feature, advantage, or mode of operation.

[0027] It should be understood by those skilled in the art that the information and signals described below may be represented using any of a variety of different techniques and methods. For example, depending in part on the specific application, in part on the desired design, in part on the corresponding technology, etc., the data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the following description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0028] In addition, various aspects are described around a sequence of actions performed by, for example, units of a computing device. It should be appreciated that the various actions described herein may be performed by a specific circuit (e.g., an application specific integrated circuit (ASIC)), by program instructions executed by one or more processors, or a combination of the two. In addition, the actions of these sequences described herein may be considered to be fully embodied in any form of non-transitory computer-readable storage medium having a corresponding set of computer instructions stored therein, which, when executed, will cause or direct the associated processor of the device to perform the functions described herein. Therefore, various aspects of the present disclosure may be embodied in a variety of different forms, all of which are contemplated to fall within the scope of protection of the present invention. In addition, for each aspect described herein, any such aspect of the corresponding form may be described herein as, for example, a "logic circuit" configured to perform the described actions.

[0029] As used herein, unless otherwise specified, the terms "user equipment" (UE) and "base station" (BS) are not intended to be specific or otherwise limited to any specific radio access technology (RAT). In general, a UE can be any wireless communication device (e.g., an onboard computer, a vehicle navigation device, a mobile phone, a router, a tablet computer, a laptop computer, a tracking device, a wearable device (e.g., a smart watch, glasses, augmented reality (AR) / virtual reality (VR) headsets, etc.), a vehicle (e.g., a car, a motorcycle, a bicycle, etc.), an Internet of Things (IoT) device, etc.) used by a user to communicate over a wireless communication network. A UE can be mobile or fixed (e.g., at certain times) and can communicate with a radio access network (RAN). As used herein, the term "UE" can be interchangeably referred to as a "mobile device", "access terminal" or "AT", "client device", "wireless device", "subscriber device", "subscriber terminal", "subscriber station", "user terminal" or UT, "mobile terminal", "mobile station" or variants thereof. In general, a UE can communicate with a core network via a RAN, and the UE can be connected to external networks such as the Internet and to other UEs through the core network. Of course, other mechanisms are also possible for the UE to connect to the core network and / or the Internet, such as through a wired access network, a wireless local area network (WLAN) network (eg, based on Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc.).

[0030] In some cases, UEs may be classified as vehicle UEs (V-UEs) or pedestrian UEs (P-UEs). A V-UE is any vehicle-mounted wireless communication device, such as a navigation system, warning system, head-up display (HUD), vehicle-mounted computer, etc. Alternatively, a V-UE may be a portable wireless communication device (e.g., a cellular phone, a tablet computer, etc.) carried by a vehicle driver or a passenger in the vehicle. Depending on the context, the term "V-UE" may refer to an in-vehicle wireless communication device or the vehicle itself. The term "vehicle" may refer to a truck, car, motorcycle, train, airplane, or any other motor vehicle. A P-UE is a portable wireless communication device carried by a pedestrian (i.e., a user who does not drive or ride, but may ride a bicycle, scooter, or other non-motor vehicle).

[0031] A base station may operate according to one of several RATs for communicating with a UE, depending on the network in which it is deployed, and may be alternatively referred to as an access point (AP), a network node, a Node B, an evolved Node B (eNB), a next generation eNB (ng-eNB), a new radio (NR) Node B (also referred to as a gNB or gNodeB), etc. A base station may be primarily used to support wireless access for a UE, including supporting data, voice, and / or signaling connections for the supported UE. In some systems, a base station may provide a pure edge node signaling function, while in other systems, it may provide additional control functions and / or network management functions. The communication link through which a UE may send a signal to a base station is referred to as an uplink (UL) channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). The communication link through which a base station may send a signal to a UE is referred to as a downlink (DL) or forward link channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc.). As used herein, the term traffic channel (TCH) may refer to an uplink / reverse or downlink / forward traffic channel.

[0032] The term "base station" may refer to a single physical transmission reception point (TRP), or may refer to multiple physical TRPs that may or may not be located at the same location. For example, where the term "base station" refers to a single physical TRP, the physical TRP may be an antenna of the base station corresponding to the cell (or several cell sectors) of the base station. Where the term "base station" refers to multiple co-located physical TRPs, the physical TRP may be an antenna array of the base station (e.g., as in a multiple-input multiple-output (MIMO) system, or where the base station employs beamforming). Where the term "base station" refers to multiple non-co-located physical TRPs, the physical TRP may be a distributed antenna system (DAS) (a network of spatially separated antennas connected to a common source via a transmission medium) or a remote radio head (RRH) (a remote base station connected to a serving base station). Alternatively, a non-co-located physical TRP may be a serving base station that receives measurement reports from a UE and a neighbor base station whose reference radio frequency (RF) signal the UE is measuring. As used herein, because the TRP is the point from which a base station sends and receives wireless signals, references to transmissions from a base station, or receptions at a base station, should be understood to refer to the specific TRP of the base station.

[0033] In some implementations of supporting positioning of UEs, a base station may not support wireless access for UEs (e.g., may not support data, voice, and / or signaling connections for UEs), but may send reference RF signals to UEs for measurement by such UEs, and / or may receive and measure signals sent by UEs. Such a base station may be referred to as a positioning beacon (e.g., when sending RF signals to UEs) and / or a position measurement unit (e.g., when receiving and measuring RF signals from UEs).

[0034] An "RF signal" includes an electromagnetic wave of a given frequency that transmits information through the space between a transmitter and a receiver. As used herein, a transmitter may send a single "RF signal" or multiple "RF signals" to a receiver. However, due to the propagation characteristics of RF signals through multipath channels, a receiver may receive multiple "RF signals" corresponding to each transmitted RF signal. The same transmitted RF signal on different paths between a transmitter and a receiver may be referred to as a "multipath" RF signal. As used herein, an RF signal may also be referred to as a "wireless signal" or simply a "signal", where it is clear from the context that the term "signal" refers to either a wireless signal or an RF signal.

[0035] According to various aspects, Figure 1An exemplary wireless communication system 100 is shown. The wireless communication system 100 (which may also be referred to as a wireless wide area network (WWAN)) may include various base stations 102 (labeled as "BS") and various UEs 104. The base stations 102 may include macrocell base stations (high-power cellular base stations) and / or small cell base stations (low-power cellular base stations). In one aspect, the macrocell base station 102 may include an eNB and / or ng-eNB when the wireless communication system 100 corresponds to an LTE network, or a gNB when the wireless communication system 100 corresponds to an NR network, or a combination of the two, and the small cell base station may include a femtocell, a picocell, a microcell, etc.

[0036] The base stations 102 may collectively form a RAN and interface with a core network 174 (e.g., an evolved packet core (EPC) or a 5G core (5GC)) via a backhaul link 122 and connect to one or more location servers 172 (the location server 172 may be part of the core network 174 or may be external to the core network 174) via the core network 174. The base stations 102 may perform functions related to one or more of the following functions, among other functions: transmission of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, multimedia broadcast multicast service (MBMS), user and device tracking, RAN information management (RIM), paging, positioning, and transmission of warning messages. The base stations 102 may communicate directly or indirectly with each other (e.g., via EPC / 5GC) via a backhaul link 134, which may be wired or wireless.

[0037] Base station 102 can communicate wirelessly with UE 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. In one aspect, base station 102 in each geographic coverage area 110 can support one or more cells. A "cell" is a logical communication entity for communicating with a base station (e.g., on a certain frequency resource called a carrier frequency, component carrier, carrier, frequency band, etc.), and a "cell" can be associated with an identifier (e.g., a physical cell identifier (PCI), an enhanced cell identifier (ECI), a virtual cell identifier (VCI), a cell global identifier (CGI), etc.) to distinguish cells operating via the same or different carrier frequencies. In some cases, different cells can be configured according to different protocol types (e.g., machine type communication (MTC), narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB) or other protocols) that can provide access to different types of UEs. Because a specific base station supports a cell, the term "cell" can refer to one or both of the logical communication entity and the base station supporting it, depending on the context. In some cases, the term "cell" may also refer to a geographic coverage area (eg, a sector) of a base station, as long as a carrier frequency can be detected and used for communications within certain portions of the geographic coverage area 110.

[0038] Although the geographic coverage areas 110 of adjacent macrocell base stations 102 may partially overlap (e.g., in a handoff region), some geographic coverage areas 110 may be substantially overlapped by larger geographic coverage areas 110. For example, a small cell base station 102' (labeled "SC" for "small cell") may have a coverage area 110' that substantially overlaps with the geographic coverage areas 110 of one or more macrocell base stations 102. A network including small cells and macrocell base stations may be referred to as a heterogeneous network. In addition, a heterogeneous network may also include a home eNB (HeNB), which may provide services to a restricted group called a closed subscriber group (CSG).

[0039] The communication links 120 between the base station 102 and the UE 104 may include uplink (also referred to as reverse link) transmissions from the UE 104 to the base station 102, and / or downlink (also referred to as forward link) transmissions from the base station 102 to the UE 104. The communication links 120 may use MIMO antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links 120 may be over one or more carrier frequencies. The allocation of carriers may be asymmetric with respect to the downlink and uplink (e.g., more or fewer carriers may be allocated for the downlink than for the uplink).

[0040] The wireless communication system 100 may also include a wireless local area network (WLAN) access point (AP) 150 that communicates with a WLAN station (STA) 152 via a communication link 154 in an unlicensed spectrum (e.g., 5 GHz). When communicating in the unlicensed spectrum, the WLAN STA 152 and / or the WLAN AP 150 may perform a clear channel assessment (CCA) or a listen-before-talk (LBT) process to determine whether the channel is available before communicating.

[0041] The small cell base station 102' can operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell base station 102' can adopt LTE or NR technology and use the same 5GHz unlicensed spectrum used by the WLAN AP 150. The small cell base station 102' using LTE / 5G in the unlicensed spectrum can improve the coverage of the access network and / or increase the capacity of the access network. NR in the unlicensed spectrum can be referred to as NR-U. LTE in the unlicensed spectrum can be referred to as LTE-U, License Assisted Access (LAA) or MulteFire.

[0042] The wireless communication system 100 may also include a mmW base station 180 operating at mmW frequencies and / or near mmW frequencies and communicating with UE 182. Extremely high frequency (EHF) is a part of RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz, with a wavelength between 1 mm and 10 mm. The radio waveforms in this band can be called millimeter waves. Near mmW can be extended downward to a frequency of 3 GHz with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, which is also called centimeter waves. Communications using mmW / near mmW radio frequency bands have high path loss and relatively short distances. The mmW base station 180 and UE 182 can use beamforming (transmitting and / or receiving) on ​​the mmW communication link 184 to compensate for the extremely high path loss and short distance. In addition, it should be understood that in an alternative configuration, one or more base stations 102 may also use mmW or near mmW and beamforming to send. Therefore, it should be understood that the foregoing description is by way of example only, and is not to be construed as limiting the various aspects disclosed herein.

[0043] Transmit beamforming is a technique for focusing an RF signal in a specific direction. Traditionally, when a network node (e.g., a base station) broadcasts an RF signal, it broadcasts the signal in all directions (omnidirectional). With transmit beamforming, the network node determines the location (relative to the transmitting network node) of a given target device (e.g., a UE) and projects a stronger downlink RF signal in that specific direction, thereby providing a faster (in terms of data) rate and a stronger RF signal to the receiving device. In order to change the directionality of the RF signal when transmitting, the network node can control the phase and relative amplitude of the RF signal at each of the one or more transmitters that broadcast the RF signal. For example, the network node can use an antenna array (called a "phased array" or "antenna array") that produces an RF beam that can be "steered" to point in different directions without actually moving the antenna. Specifically, the RF current from the transmitter is fed to each antenna in the correct phase relationship so that the radio waves from different antennas are superimposed to increase the radiation in the desired direction, while canceling to suppress the radiation in the undesired direction.

[0044] The transmit beams can be quasi-co-located, which means that they appear to have the same parameters in the receiver (e.g., UE) regardless of whether the transmit antennas of the network nodes themselves are physically co-located. In NR, there are four types of quasi-co-location (QCL) relationships. Specifically, a given type of QCL relationship means that certain parameters about the second reference RF signal of the second beam can be derived from information about the source reference RF signal of the source beam. Therefore, if the source reference RF signal is QCL type A, the receiver can use the source reference RF signal to estimate the Doppler shift, Doppler spread, average delay and delay spread of the second reference RF signal sent on the same channel. If the source reference RF signal is QCL type B, the receiver can use the source reference RF signal to estimate the Doppler shift and Doppler spread of the second reference RF signal sent on the same channel. If the source reference RF signal is QCL type C, the receiver can use the source reference RF signal to estimate the Doppler shift and average delay of the second reference RF signal sent on the same channel. If the source reference RF signal is QCL type D, the receiver may use the source reference RF signal to estimate spatial reception parameters of a second reference RF signal transmitted on the same channel.

[0045] In receive beamforming, a receiver uses a receive beam to amplify an RF signal detected on a given channel. For example, the receiver may increase a gain setting and / or adjust a phase setting of an antenna array in a particular direction to amplify the RF signal received from that direction (e.g., to increase its gain level). Therefore, when a receiver is said to form a beam in a certain direction, it means that the beam gain in that direction is higher relative to the beam gain in other directions, or that the beam gain in that direction is the highest compared to the beam gain in that direction of all other receive beams available to the receiver. This results in a stronger received signal strength (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal to interference plus noise ratio (SINR), etc.) for the RF signal received from that direction.

[0046] The receive beams may be spatially correlated. The spatial relationship means that the parameters of the transmit beam of the second reference signal may be derived from the information about the receive beam of the first reference signal. For example, the UE may use a specific receive beam to receive one or more reference downlink reference signals (e.g., positioning reference signal (PRS), tracking reference signal (TRS), phase tracking reference signal (PTRS), cell-specific reference signal (CRS), channel state information reference signal (CSI-RS), primary synchronization signal (PSS), secondary synchronization signal (SSS), synchronization signal block (SSB), etc.) from a base station. The UE may then form a transmit beam for sending one or more uplink reference signals (e.g., uplink positioning reference signal (UL-PRS), sounding reference signal (SRS), demodulation reference signal (DMRS), PTRS, etc.) to the base station based on the parameters of the receive beam.

[0047] It should be noted that a "downlink" beam can be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if the base station is forming a downlink beam to send a reference signal to the UE, the downlink beam is a transmit beam. However, if the UE is forming a downlink beam, it is a receive beam for receiving downlink reference signals. Similarly, an "uplink" beam can be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if the base station is forming an uplink beam, it is an uplink receive beam, and if the UE is forming an uplink beam, it is an uplink transmit beam.

[0048] In 5G, the spectrum in which wireless nodes (e.g., base stations 102 / 180, UEs 104 / 182) operate is divided into multiple frequency ranges FR1 (from 450 to 6000 MHz), FR2 (from 24250 to 52600 MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). The mmW band generally includes the FR2, FR3, and FR4 frequency ranges. Therefore, the terms "mmW" and "FR2" or "FR3" or "FR4" are generally used interchangeably.

[0049] In a multi-carrier system (e.g., 5G), one of the carrier frequencies is called the "primary carrier" or "anchor carrier" or "primary serving cell" or "PCell", and the remaining carrier frequencies are called "secondary carriers" or "secondary serving cells" or "SCells". In carrier aggregation, the anchor carrier is a carrier operating on the primary frequency (e.g., FR1) used by the UE 104 / 182 and the cell in which the UE 104 / 182 performs an initial radio resource control (RRC) connection establishment procedure or initiates an RRC connection re-establishment procedure. The primary carrier carries all common control channels and UE-specific control channels and can be a carrier in a licensed frequency (however, this is not always the case). The secondary carrier is a carrier operating on a second frequency (e.g., FR2), which can be configured once an RRC connection is established between the UE 104 and the anchor carrier, and can be used to provide additional radio resources. In some cases, the secondary carrier can be a carrier in an unlicensed frequency. The auxiliary carrier may contain only necessary signaling information and signals, for example, since the main uplink and downlink carriers are usually UE-specific, those UE-specific information and signals may not be present in the auxiliary carrier. This means that different UEs 104 / 182 in a cell can have different downlink primary carriers. The same is true for the uplink primary carrier. The network is able to change the primary carrier of any UE 104 / 182 at any time. For example, this is done to balance the load on different carriers. Because a "serving cell" (whether a PCell or an SCell) corresponds to a carrier frequency / component carrier on which some base stations are communicating, the terms "cell", "serving cell", "component carrier", "carrier frequency", etc. can be used interchangeably.

[0050] For example, see still Figure 1, one of the frequencies utilized by the macrocell base station 102 may be an anchor carrier (or "PCell"), and the other frequencies utilized by the macrocell base station 102 and / or the mmW base station 180 may be supplementary carriers ("SCells"). Simultaneous transmission and / or reception of multiple carriers enables the UE 104 / 182 to significantly increase its data transmission and / or reception rate. For example, two 20 MHz aggregated carriers in a multi-carrier system theoretically increase the data rate by two times (i.e., 40 MHz) compared to the rate achieved by a single 20 MHz carrier.

[0051] The wireless communication system 100 may also include one or more UEs (eg, UE 190) indirectly connected to one or more communication networks via one or more device-to-device (D2D) or peer-to-peer (P2P) links. Figure 1 In the example of FIG. 1 , UE 190 has a D2D P2P link 192 with one of UEs 104 connected to one of base stations 102 (e.g., through which UE 190 can indirectly obtain a cellular connection), and has a D2D P2P link 194 with a WLAN STA 152 connected to WLAN AP 150 (through which UE 190 can indirectly obtain a WLAN-based Internet connection). In one example, any well-known D2D RAT (e.g., LTE Direct (LTE-D), WiFi Direct (WiFi-D), etc.) to support D2D P2P links 192 and 194.

[0052] Leveraging NR's increased data rates and reduced latency, among other things, vehicle-to-everything (V2X) communication technologies are being implemented to support intelligent transportation system (ITS) applications, such as wireless communication between vehicles (vehicle-to-vehicle V2V), between vehicles and roadside infrastructure (V2I), and between vehicles and pedestrians (V2P). The goal is to enable vehicles to sense their surroundings and communicate that information to other vehicles, infrastructure, and personal mobile devices. This vehicle communication will enable safety, mobility, and environmental improvements that current technology cannot provide. Once fully implemented, the technology is expected to reduce 80% of non-damage vehicle collisions.

[0053] Still refer to Figure 1, the wireless communication system 100 may include a plurality of V-UEs 160 that may communicate with a base station 102 via a communication link 120 (e.g., using a Uu interface). The V-UEs 160 may also communicate directly with each other via a wireless unicast link 162, with a roadside access point 164 (also referred to as a “roadside unit”) via a sidelink 166, or with a UE 104 via a sidelink 168 using a P2P / D2D protocol (e.g., “PC5”, LTE V2X D2D interface) or ProSe direct communication. The sidelink communication may be used for D2D medium sharing, V2V communication, V2X communication (e.g., cellular V2X (cV2X) communication, enhanced V2X (eV2X) communication, etc.), emergency rescue applications, etc. One or more of a group of V-UEs 160 utilizing D2D communication may be within a geographic coverage area 110 of the base station 102. Other V-UEs 160 in such a group may be outside of the geographic coverage area 110 of the base station 102 or may not be able to receive transmissions from the base station 102. In some cases, a group of V-UEs 160 communicating via D2D communications may utilize a one-to-many (1:M) system, where each V-UE 160 transmits to each other V-UE 160 in the group. In some cases, the base station 102 facilitates scheduling of resources for D2D communications. In other cases, D2D communications are performed between V-UEs 160 without the involvement of the base station 102. It should be noted that although Figure 1 Two V-UEs 160 are shown communicating via a side link, but it should be understood that Figure 1 Any two or more UEs shown in FIG. 1 may communicate via a sidelink, and reference to V-UE 160 is merely an example.

[0054] In one aspect, V-UE 160 and Figure 1 Any other UE shown in the figure may have a lateral link manager 170. The lateral link manager 170 may be a hardware, software, or firmware component that, when executed, causes the V-UE 160 to perform the operations described herein. For example, the lateral link manager 170 may be a software module stored in a memory of the V-UE 160 and executable by a processor of the V-UE 160. As another example, the lateral link manager 170 may be a hardware circuit (e.g., an ASIC, a field programmable gate array (FPGA), etc.) within the V-UE 160. It should be noted that although only one UE (V-UE 160) is shown as including the lateral link manager 170, any of the UEs shown may include the lateral link manager 170.

[0055] In one aspect, the sidelinks 162, 166, 168 can operate on a communication medium of interest, which can be shared with other communications between other vehicles and / or infrastructure access points, as well as other RATs. The "medium" can consist of one or more frequency, time, and / or spatial communication resources (e.g., covering one or more channels on one or more carriers) associated with communications between one or more transmitter / receiver pairs.

[0056] In one aspect, the side links 162, 166, 168 may be cV2X links. The first generation of cV2X has been standardized in LTE, and the next generation is expected to be defined in NR. cV2X is a cellular technology that also supports device-to-device communications. In the United States and Europe, cV2X is expected to operate in licensed ITS bands below 6 GHz. Other bands may be allocated in other countries. Therefore, as a specific example, the medium of interest used by the side links 162, 166, 168 may correspond to at least a portion of a licensed ITS band below 6 GHz. However, the present disclosure is not limited to this band or cellular technology.

[0057] In one aspect, the side links 162, 166, 168 can be dedicated short-range communication (DSRC) links. DSRC is a unidirectional or bidirectional short-range to medium-range wireless communication protocol that uses the Wireless Access to Vehicular Environment (WAVE) protocol for V2V, V2I, and V2P communications, also known as IEEE 802.11p. IEEE 802.11p is an approved revision of the IEEE 802.11 standard and operates in the licensed ITS band 5.9GHz (5.85-5.925GHz) in the United States. In Europe, IEEE 802.11p operates in the ITS G5A band (5.875-5.905MHz). Other bands may be allocated in other countries. The V2V communications briefly described above occur on a safety channel, which in the United States is typically a 10MHz channel dedicated to safety purposes. The remainder of the DSRC band (75MHz in total bandwidth) is intended for other services of interest to drivers, such as road rules, toll collection, parking automation, and the like. Thus, as a specific example, the medium of interest 162, 166, 168 used by the sidelink may correspond to at least a portion of the licensed ITS band at 5.9 GHz.

[0058] Alternatively, the medium of interest may correspond to at least a portion of an unlicensed frequency band shared among various RATs. Although different licensed frequency bands have been reserved for certain communication systems (e.g., by government agencies such as the Federal Communications Commission (FCC) in the United States), these systems (particularly those employing small cell access points) have recently expanded operations to unlicensed frequency bands, such as the unlicensed National Information Infrastructure (U-NII) frequency bands used by wireless local area network (WLAN) technologies, most notably the IEEE 802.11x WLAN technology commonly referred to as "Wi-Fi". Example systems of this type include different variations of CDMA systems, TDMA systems, FDMA systems, orthogonal FDMA (OFDMA) systems, single carrier FDMA (SC-FDMA) systems, and the like.

[0059] The communication between V-UEs 160 is referred to as V2V communication, the communication between V-UEs 160 and one or more roadside access points 164 is referred to as V2I communication, and the communication between V-UEs 160 and one or more UEs 104 (where UEs 104 are P-UEs) is referred to as V2P communication. V2V communication between V-UEs 160 may include, for example, information about the position, speed, acceleration, heading, and other vehicle data of the V-UEs 160. The V2I information received at the V-UEs 160 from one or more roadside access points 164 may include, for example, road rules, parking automation information, and the like. V2P communication between V-UEs 160 and UEs 104 may include, for example, information about the position, speed, acceleration, and heading of the V-UEs 160, and information about the position, speed (for example, when a user is carrying the UE 104 on a bicycle), and heading of the UEs 104.

[0060] It should be noted that although Figure 1 Only two of the UEs are shown as V-UEs (V-UE 160), but any of the UEs shown (e.g., UEs 104, 152, 182, 190) may be V-UEs. In addition, although only UE 182 is described as being capable of beamforming, any of the UEs shown (including V-UE 160) may be capable of beamforming. In the case where V-UEs 160 are capable of beamforming, they may beamform toward each other (i.e., toward other V-UEs 160), toward roadside access points 164, toward other UEs (e.g., UEs 104, 152, 182, 190), and so on. Thus, in some cases, V-UE 160 may utilize beamforming on sidelinks 162, 166, and 168.

[0061] According to various aspects, Figure 2AAn exemplary wireless network structure 200 is shown. For example, the 5GC 210 (also referred to as the Next Generation Core (NGC)) can be viewed functionally as a control plane function (C-plane) 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and a user plane function (U-plane) 212 (e.g., UE gateway function, access to data networks, IP routing, etc.), which operate in coordination to form a core network. The user plane interface (NG-U) 213 and the control plane interface (NG-C) 215 connect the gNB 222 to the 5GC 210, in particular to the user plane function 212 and the control plane function 214, respectively. In another configuration, the ng-eNB 224 can also be connected to the 5GC 210 via the NG-C 215 to the control plane function 214 and the NG-U 213 to the user plane function 212. In addition, the ng-eNB 224 can communicate directly with the gNB 222 via the backhaul connection 223. In some configurations, the new RAN 220 may have only one or more gNBs 222, while other configurations include one or more of both ng-eNBs 224 and gNBs 222. Either gNB 222 or ng-eNB 224 (or both) may communicate with a UE 204 (e.g., any of the UEs depicted herein). Figure 2A Only two UEs 204 are shown, and it should be understood that there may be more than two UEs 204, and two or more UEs 204 may form a sidelink communication group. In one aspect, two or more UEs 204 may communicate with each other via a wireless unicast sidelink 242, which may correspond to a wireless unicast sidelink 242. Figure 1 Alternatively, each pair of UEs 204 may communicate via a different side link 242 than other pairs of UEs 204.

[0062] Another optional aspect may include a location server 230 that can communicate with the 5GC 210 to provide location assistance for the UE 204. The location server 230 can be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules distributed on multiple physical servers, etc.), or can also correspond to a single server respectively. The location server 230 can be configured to support one or more location services for the UE 204, and the UE 204 can be connected to the location server 230 via the core network, the 5GC 210, and / or via the Internet (not shown). In addition, the location server 230 can be integrated into a component of the core network, or alternatively can be external to the core network.

[0063] According to various aspects, Figure 2B Another exemplary wireless network structure 250 is shown. For example, the 5GC 260 can be viewed functionally as a control plane function provided by an access and mobility management function (AMF) 264, and a user plane function provided by a user plane function (UPF) 262, which operate in coordination to form a core network (i.e., the 5GC 260). The user plane interface 263 and the control plane interface 265 connect the ng-eNB 224 to the 5GC 260, in particular to the UPF 262 and the AMF 264, respectively. In another configuration, the gNB 222 can also be connected to the 5GC 260 via a control plane interface 265 to the AMF 264 and a user plane interface 263 to the UPF 262. In addition, the ng-eNB 224 can communicate directly with the gNB 222 via a backhaul connection 223 (with or without a gNB direct connection to the 5GC 260). In some configurations, the new RAN 220 may have only one or more gNBs 222, while other configurations include one or more of ng-eNBs 224 and gNBs 222. The base stations of the new RAN 220 communicate with the AMF 264 via the N2 interface and with the UPF 262 via the N3 interface. Either the gNB 222 or the ng-eNB 224 (or both) may communicate with the UE 204 (e.g., any UE described herein). In one aspect, two or more UEs 204 may communicate with each other via a wireless unicast sidelink 242, which may correspond to a wireless unicast sidelink 242. Figure 1 The wireless unicast side link 162 in.

[0064] The functions of AMF 264 include registration management, connection management, reachability management, mobility management, lawful interception, transmission of session management (SM) messages between UE 204 and session management function (SMF) 266, transparent proxy service for routing SM messages, access authentication and access authorization, transmission of short message service (SMS) messages between UE 204 and short message service function (SMSF) (not shown), and security anchor function (SEAF). AMF 264 also interacts with authentication server function (AUSF) (not shown) and UE 204, and receives intermediate keys established as a result of the UE 204 authentication process. In the case of authentication based on UMTS (Universal Mobile Telecommunications System) User Identity Module (USIM), AMF 264 retrieves security materials from AUSF. The functions of AMF 264 also include security context management (SCM). SCM receives keys from SEAF, which are used to derive keys specific to access networks. The functions of AMF 264 also include location service management for regulatory services, transmission of location service messages between UE 204 and location management function (LMF) 270 (which acts as location server 230), transmission of location service messages between new RAN 220 and LMF 270, allocation of EPS bearer identifiers for interworking with Evolved Packet System (EPS), and notification of mobility events of UE 204. In addition, AMF 264 also supports the functions of non-3GPP (3rd Generation Partnership Project) access networks.

[0065] The functions of UPF 262 include: acting as an anchor point for intra-RAT / inter-RAT mobility (when applicable), acting as an external protocol data unit (PDU) session point for interconnection to a data network (not shown), providing packet routing and forwarding, packet inspection, user plane policy rule enforcement (e.g., gating, redirection, flow control), lawful interception (user plane collection), traffic usage reporting, user plane quality of service (QoS) processing (e.g., uplink / downlink rate enforcement, reflective QoS marking in downlink), uplink traffic verification (service data flow (SDF) to QoS flow mapping), transport layer packet marking in uplink and downlink, downlink packet buffering and downlink data notification triggering, and sending and forwarding of one or more "end markers" to the source RAN node. UPF 262 can also support the transmission of location service messages between UE 204 and a positioning server (e.g., Secure User Plane Location (SUPL) Location Platform (SLP) 272) on the user plane.

[0066] The functions of SMF 266 include: session management, UE Internet Protocol (IP) address allocation and management, selection and control of user plane functions, configuration of service control at UPF 262 to route services to appropriate destinations, control of part of policy enforcement and QoS, and downlink data notification. The interface through which SMF 266 communicates with AMF 264 is called the N11 interface.

[0067] Another optional aspect may include LMF 270, which can communicate with 5GC 260 to provide location assistance for UE 204. LMF 270 can be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules distributed on multiple physical servers, etc.), or alternatively, each module can correspond to a single server. LMF 270 can be configured to support one or more positioning services for UE 204, which can be connected to LMF 270 via the core network, 5GC 260, and / or via the Internet (not shown). SLP272 can support similar functionality as LMF 270, but LMF 270 can communicate with AMF 264, new RAN 220, and UE 204 on the control plane (e.g., using interfaces and protocols intended to transmit signaling messages rather than voice or data), and SLP272 can communicate with UE 204 and external clients ( Figure 2B (not shown) to communicate (e.g., using protocols designed to carry voice and / or data, such as the Transmission Control Protocol (TCP) and / or IP).

[0068] Figure 3 According to aspects of the present disclosure, an example of a wireless communication system 300 that supports unicast sidelink establishment is shown. In some examples, the wireless communication system 300 can implement aspects of the wireless communication systems 100, 200, and 250. The wireless communication system 300 can include a first UE 302 and a second UE 304, which can be examples of any UE described herein. As a specific example, the UEs 302 and 304 can correspond to Figure 1 V-UE 160 in. Figure 3 In the example of , UE 302 may attempt to establish a unicast connection with UE 304 via a sidelink, which may be a V2X communication link between UE 302 and UE 304. Additionally or alternatively, a unicast connection on a sidelink may generally be used for sidelink communications between any two UEs. Thus, the established sidelink connection may correspond to Figure 1 The side links 162 and / or 168 and / or Figure 2A and Figure 2BThe wireless unicast side link 242 in FIG. Figure 3 As shown in the upper part of , a side link connection can be established for signaling in an omni-directional frequency range (e.g., FR1), such as Figure 3 The lower portion of shows the mmW frequency range (eg, FR2) used for data transmission. In some cases, UE 302 may be referred to as an initiator UE initiating a unicast connection procedure, and UE 304 may be referred to as a target UE, which is the initiator UE as the target of the unicast connection procedure.

[0069] In order to establish a unicast connection, access stratum (AS) (a functional layer in the UMTS and LTE protocol stacks between the RAN and the UE, responsible for transmitting data and managing radio resources over a wireless link, also known as "Layer 2" or "L2") parameters may be configured and negotiated between UE 302 and UE 304. For example, transmission and reception capability matching may be negotiated between UE 302 and UE 304. Each UE may have different capabilities (e.g., transmission and reception capabilities, 64 quadrature amplitude modulation (QAM), transmission diversity, carrier aggregation (CA) capabilities, supported communication bands, etc.). In some cases, different services may be supported at the upper layers of the corresponding protocol stacks of UE 302 and UE 304. In addition, a security association for a unicast connection may be established between UE 302 and UE 304. Unicast services may benefit from link-level security protection (e.g., integrity protection). The security requirements of different wireless communication systems may be different. For example, V2X and Uu systems may have different security requirements (e.g., Uu security does not include confidentiality protection). Additionally, IP configuration (eg, IP version, address, etc.) may be negotiated for a unicast connection between UE 302 and UE 304 .

[0070] In some cases, UE 304 may create a service announcement (e.g., a service capability message) for transmission over a cellular network (e.g., cV2X) to help establish a unicast connection. Typically, UE 302 may identify and locate candidates for unicast communication based on a basic service message (BSM) broadcasted unencrypted by a nearby UE (e.g., UE 304). The BSM may include location information, security and identity information, and vehicle information (e.g., speed, maneuvering, size, etc.) of the corresponding UE. However, for different wireless communication systems (e.g., D2D or V2X communication), the discovery channel may not be configured to enable UE 302 to detect the BSM. Therefore, the service announcement (e.g., discovery signal) sent by UE 304 and other nearby UEs may be an upper layer signal and broadcast (e.g., in an NR sidelink broadcast). In some cases, UE 304 may include one or more parameters of itself in the service announcement, including connection parameters and / or capabilities it possesses. Then, UE 302 may monitor and receive the broadcast service announcement to identify potential UEs for corresponding unicast connections. In some cases, UE 302 may identify potential UEs based on the capabilities indicated by each UE in their respective service announcements.

[0071] The service announcement may include a method to help UE 302 (eg, or any initiator UE) identify the UE that sent the service announcement. Figure 3 304 in the example of ). For example, the service announcement may include channel information capable of sending direct communication requests. In some cases, the channel information may be RAT-specific (e.g., LTE or NR) and may include a resource pool in which UE302 sends communication requests. In addition, if the destination address is different from the current address (e.g., the address of the streaming provider or the address of the UE sending the service announcement), the service announcement may include a specific destination address of the UE (e.g., a layer 2 destination address). The service announcement may also include a network or transport layer for UE 302 to send communication requests on. For example, the network layer (also known as "layer 3" or "L3") or the transport layer (also known as "layer 4" or "L4") may indicate the port number of the application for the UE to send the service announcement. In some cases, IP addressing may not be required if the signaling (e.g., PC5 signaling) directly carries a protocol (e.g., real-time transport protocol (RTP)) or provides a locally generated random protocol. In addition, the service announcement may include a protocol for certificate establishment and parameters related to QoS.

[0072] After identifying potential unicast connection targets ( Figure 3 304 in the example), then the initiator UE ( Figure 3304) can send a connection request 315 to the identified target UE 304. In some cases, the connection request 315 can be a first RRC message (e.g., an RRCDirectConnectionSetupRequest message) sent by the UE 302 to request a unicast connection with the UE 304. For example, the unicast connection can utilize a PC5 interface for a unicast link, and the connection request 315 can be an RRC connection establishment request message. In addition, the UE 302 can use the sidelink signaling radio bearer 305 to transmit the connection request 315.

[0073] After receiving the connection request 315, the UE 304 may determine whether to accept or reject the connection request 315. The UE 304 may make this determination based on transmit / receive capabilities, the ability to accommodate unicast connections over the sidelink, a specific service indicated for the unicast connection, content to be transmitted over the unicast connection, or a combination thereof. For example, if the UE 302 wants to use a first RAT to send or receive data, but the UE 304 does not support the first RAT, the UE 304 may reject the connection request 315. Additionally or alternatively, the UE 304 may reject the connection request 315 based on the inability to accommodate unicast connections over the sidelink due to limited radio resources, scheduling issues, etc. Therefore, the UE 304 may send an indication of whether the request is accepted or rejected in a connection response 320. Similar to the UE 302 and the connection request 315, the UE 304 may use the sidelink signaling radio bearer 310 to transmit the connection response 320. Additionally, the connection response 320 may be a second RRC message (eg, an RRCDirectConnectionResponse message) sent by the UE 304 in response to the connection request 315 .

[0074] In some cases, the sidelink signaling radio bearers 305 and 310 may be the same sidelink radio signal bearer, or may be separate sidelink signaling radio bearers. Thus, a radio link control (RLC) layer acknowledgement mode (AM) may be used for the sidelink signaling radio bearers 305 and 310. A UE supporting unicast connections may monitor a logical channel associated with the sidelink signaling radio bearer. In some cases, the AS layer (i.e., Layer 2) may deliver information directly via RRC signaling (e.g., control plane) rather than the V2X layer (e.g., data plane).

[0075] If the connection response 320 indicates that the UE 304 accepted the connection request 315, the UE 302 may send a connection setup 325 message on the sidelink signaling radio bearer 305 to indicate that the unicast connection setup is complete. In some cases, the connection setup 325 may be a third RRC message (e.g., an RRCDirectConnectionSetupComplete message). Each of the connection request 315, the connection response 320, and the connection setup 325 may use basic capabilities when transmitted from one UE to another UE to enable each UE to receive and decode the corresponding transmission (e.g., RRC message).

[0076] In addition, an identifier may be used for each of the connection request 315, the connection response 320, and the connection establishment 325 (e.g., RRC signaling). For example, the identifier may indicate which UE 302 / 304 is transmitting which message and / or which UE 302 / 304 the message is intended for. For a physical (PHY) channel, the RRC signaling and any subsequent data transmission may use the same identifier (e.g., a Layer 2 ID). However, for a logical channel, the identifier may be separate for RRC signaling and for data transmission. For example, on a logical channel, RRC signaling and data transmission may be processed differently and have different acknowledgment (ACK) feedback messages. In some cases, for an RRC message, a physical (PHY) layer ACK may be used to ensure that the corresponding message is correctly sent and received.

[0077] One or more information elements may be included in the connection request 315 and / or the connection response 320 for UE 302 and / or UE 304, respectively, to enable negotiation of corresponding AS layer parameters for unicast connection. For example, UE 302 and / or UE 304 may include packet data convergence protocol (PDCP) parameters in the corresponding unicast connection establishment message to set the PDCP context for the unicast connection. In some cases, the PDCP context may indicate whether PDCP duplication is used for the unicast connection. In addition, UE 302 and / or UE 304 may include RLC parameters when establishing a unicast connection to set the RLC context for the unicast connection. For example, the RLC context may indicate whether AM (e.g., using a reordering timer (t-reordering)) or unacknowledged mode (UM) is used for the RLC layer of unicast communication.

[0078] In addition, UE 302 and / or UE 304 may include medium access control (MAC) parameters to set up a MAC context for a unicast connection. In some cases, the MAC context may implement a resource selection algorithm, a hybrid automatic repeat request (HARQ) feedback scheme (e.g., ACK or negative ACK (NACK) feedback), parameters of the HARQ feedback scheme, carrier aggregation, or a combination thereof for the unicast connection. In addition, UE 302 and / or UE 304 may include PHY layer parameters when establishing a unicast connection to set up a PHY layer context for the unicast connection. For example, the PHY layer context may indicate a transport format for the unicast connection (unless a transport profile is included for each UE 302 / 304) and a radio resource configuration (e.g., a bandwidth part (BWP), a parameter set, etc.). These information elements may support different frequency range configurations (e.g., FR1 and FR2).

[0079] In some cases, a security context may also be set for the unicast connection (e.g., after sending the connection establishment 325 message). Before a security association (e.g., a security context) is established between UE 302 and UE 304, the sidelink signaling radio bearers 305 and 310 may not be protected. After the security association is established, the sidelink signaling radio bearers 305 and 310 may be protected. Therefore, the security context may enable secure data transmission over the unicast connection and the sidelink signaling radio bearers 305 and 310. In addition, IP layer parameters (e.g., link-local IPv4 or IPv6 addresses) may also be negotiated. In some cases, the IP layer parameters may be negotiated by the upper layer control protocol running after the RRC signaling is established (e.g., the unicast connection is established). As described above, UE 304 may decide whether to accept or reject the connection request 315 based on the specific service indicated for the unicast connection and / or the content to be sent over the unicast connection (e.g., upper layer information). The specific service and / or content may also be indicated by the upper layer control protocol running after the RRC signaling is established.

[0080] After establishing the unicast connection, UE 302 and UE 304 may communicate via sidelink 330 using the unicast connection, wherein sidelink data 335 is transmitted between the two UEs 302 and 304. Sidelink 330 may correspond to Figure 1 The side links 162 and / or 168 in Figure 2A and Figure 2B304. In some cases, the side link data 335 may include an RRC message transmitted between two UEs 302 and 304. In order to maintain the unicast connection on the side link 330, UE 302 and / or UE 304 may transmit a keep-alive message (e.g., an RRCDirectLinkAlive message, a fourth RRC message, etc.). In some cases, the keep-alive message may be triggered periodically or on demand (e.g., an event trigger). Therefore, the triggering and transmission of the keep-alive message may be called by UE 302 or by both UE 302 and UE 304. Additionally or alternatively, a MAC control element (CE) (e.g., defined on the side link 330) may be used to monitor the unicast connection state on the side link 330 and maintain the connection. When the unicast connection is no longer needed (e.g., UE 302 travels far enough from UE 304), UE 302 and / or UE 304 may start a release process to discard the unicast connection on the side link 330. Therefore, no subsequent RRC messages are sent between UE 302 and UE 304 over the unicast connection.

[0081] Figure 4 4 is a block diagram illustrating various components of an exemplary UE 400 according to various aspects of the present disclosure. In one aspect, UE 400 may correspond to any UE described herein. As a specific example, UE 400 may be a V-UE (e.g., Figure 1 For simplicity, the common data bus is used to connect the V-UE 160 in the side link communication. Figure 4 The various features and functions shown in the block diagram are connected together, and the common data bus is intended to represent that these different features and functions are operably coupled together. It should be recognized by those skilled in the art that other connections, mechanisms, features, functions, etc. can be provided and adapted as needed to operably couple and configure the actual UE. In addition, it should be recognized that Figure 4 One or more of the features or functions shown in the examples may be further subdivided or may be Figure 4 Two or more of the features or functions shown may be combined.

[0082] The UE 400 may include at least one transceiver 404 connected to one or more antennas 402, which provides means (e.g., means for transmitting, means for receiving, means for measuring, means for tuning, means for refraining from transmitting, etc.) for communicating with other network nodes such as V-UEs (e.g., V-UE 160), infrastructure access points (e.g., roadside access points 164), P-UEs (e.g., UE 104), base stations (e.g., base station 102), etc., over one or more communication links (e.g., communication links 120, side links 162, 166, 168, mmW communication links 184) via at least one designated RAT (e.g., C-V2X or IEEE 802.11p). The transceiver 404 may be configured differently to transmit and encode signals (e.g., messages, indications, information, etc.), and conversely, to receive and decode signals (e.g., messages, indications, information, pilots, etc.), respectively, according to the designated RAT.

[0083] As used herein, a "transceiver" may include at least one transmitter and at least one receiver in an integrated device (e.g., a transmitter circuit and a receiver circuit embodied as a single communication device), in some implementations, may include a separate transmitter device and a separate receiver device, or in other embodiments, may be embodied in other ways. In one aspect, the transmitter may include or be coupled to multiple antennas (e.g., antenna 402) (e.g., an antenna array), which allows the UE 400 to perform transmit "beamforming" as described herein. Similarly, the receiver may include or be coupled to multiple antennas (e.g., antenna 402) (e.g., an antenna array), which allows the UE 400 to perform receive beamforming as described herein. In one aspect, the transmitter and receiver may share the same multiple antennas (e.g., antenna 402) so that the UE 400 can only receive or transmit at a given time, rather than simultaneously. In some cases, a transceiver may not be able to provide both transmit and receive functions. For example, in some designs, low-function receiver circuits may be used to reduce costs when full communication is not required (e.g., a receiver chip or similar circuit that only provides low-level sniffing).

[0084] UE 400 may also include a satellite positioning service (SPS) receiver 406. SPS receiver 406 may be connected to one or more antennas 402 and provide a unit for receiving and / or measuring satellite signals. SPS receiver 406 may include any appropriate hardware and / or software for receiving and processing SPS signals (e.g., global positioning system (GPS) signals). SPS receiver 406 appropriately requests information and operations from other systems and uses measurements obtained by any appropriate SPS algorithm to perform calculations required to determine the location of UE 400.

[0085] One or more sensors 408 may be coupled to the processing system 410 to provide information for sensing or detecting information related to the status and / or environment of the UE 400, such as speed, heading (e.g., compass heading), headlight status, fuel consumption, etc. For example, the one or more sensors 408 may include a speedometer, a tachometer, an accelerometer (e.g., a micro-electromechanical system (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometric altimeter), etc.

[0086] The processing system 410 may include one or more microprocessors, microcontrollers, ASICs, processing cores, digital signal processors, etc. that provide processing functions and other computing and control functions. The processing system 410 may include any form of logic suitable for executing or causing the components of the UE 400 to perform at least the techniques provided herein. Thus, the processing system 410 may provide a unit for processing, such as a unit for determining, a unit for calculating, a unit for receiving, a unit for sending, a unit for indicating, etc.

[0087] The processing system 410 may also be coupled to a memory 414, which provides a means for storing data and software instructions to perform programmed functions within the UE 400. The memory 414 may be on the processing system 410 (e.g., in the same integrated circuit (IC) package) and / or the memory 414 may be external to the processing system 410 and functionally coupled via a data bus.

[0088] UE 400 may include a user interface 450 that provides means for providing any suitable interface system, such as a microphone / speaker 452, a keypad 454, and a display 456 that allow a user to interact with UE 400. Microphone / speaker 452 provides voice communication services with UE 400. Keypad 454 includes any suitable buttons for user input to UE 400. Display 456 includes any suitable display, such as a backlit liquid crystal display (LCD), and may further include a touch screen display for additional user input modes.

[0089] In one aspect, UE 400 may include a lateral link manager 470 coupled to processing system 410. Lateral link manager 470 (which may correspond to Figure 1400) can be a hardware, software, or firmware component that, when executed, causes UE 400 to perform the operations described herein. For example, lateral link manager 470 can be a software module stored in memory 414 and executable by processing system 410. As another example, lateral link manager 470 can be a hardware circuit (e.g., ASIC, FPGA, etc.) within UE 400. Thus, lateral link manager 470 can provide a means for performing the functions described herein.

[0090] Various frame structures may be used to support downlink and uplink transmissions between network nodes (eg, base stations and UEs). Figure 5 5 is a diagram 500 illustrating an example of a frame structure in accordance with aspects of the present disclosure. However, one of ordinary skill in the art will appreciate that the frame structure for any particular application may be different.

[0091] LTE, and in some cases NR, utilizes OFDM on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. However, unlike LTE, NR can also choose to use OFDM on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, frequency bins, etc. Each subcarrier can be modulated with data. Typically, modulation symbols are sent in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the spacing of the subcarriers can be 15kHz, and the minimum resource allocation (resource block) can be 12 subcarriers (or 180kHz). Therefore, for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), the nominal fast Fourier transform (FFT) size can be equal to 128, 256, 512, 1024, or 2048, respectively. The system bandwidth may also be divided into subbands. For example, one subband may cover 1.08 MHz (ie, 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, respectively.

[0092] LTE supports a single parameter set (subcarrier spacing, symbol length, etc.). In contrast, NR can support multiple parameter sets (μ), for example, 15kHz, 30kHz, 60kHz, 120kHz and 240kHz or larger subcarrier spacing may be available. Table 1 provided below lists some different parameters for different NR parameters.

[0093]

[0094] Table 1

[0095] exist Figure 5 In the example of , a parameter set of 15 kHz is used. Therefore, in the time domain, a 10 millisecond (ms) frame is divided into 10 equally sized subframes, each subframe is 1 ms, and each subframe includes one time slot. Figure 5 , time is represented horizontally (eg, on the X-axis) and increases from left to right, while frequency is represented vertically (eg, on the Y-axis) and increases (or decreases) from bottom to top.

[0096] A time slot can be represented using a resource grid, each of which includes one or more time-parallel resource blocks (RBs) (also called physical RBs (PRBs)) in the frequency domain. The resource grid is further divided into multiple resource elements (REs). An RE can correspond to one symbol length in the time domain and one subcarrier in the frequency domain. Figure 5 In the digital scheme of , for a normal cyclic prefix (CP), an RB can contain 12 consecutive subcarriers in the frequency domain, 7 consecutive symbols in the time domain, and a total of 84 REs. For an extended CP, an RB can contain 12 consecutive subcarriers in the frequency domain, 6 consecutive symbols in the time domain, and a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

[0097] Some REs carry reference (pilot) signals (RS). Downlink reference signals (DL-RS) may include DL-PRS, TRS, PTRS, CRS, CSI-RS, DMRS, PSS, SSS, SSB, etc. Uplink reference signals (UL-RS) may include SRS, SRS for positioning (referred to as "UL-PRS"), DMRS, etc. Sidelink reference signals may include DMRS and other sidelink synchronization signals.

[0098] Figure 5 Example locations of REs carrying DMRS (labeled "R") are shown. In one aspect, the reference signal can be a demodulation reference signal (DMRS). The DMRS is specific to a particular UE and is used to estimate the radio channel between the transmitter and the receiver to demodulate the associated physical channel. The transmitter can beamform the DMRS, keep it within the scheduled resources, and transmit it in the downlink or uplink only when necessary. In addition, multiple orthogonal DMRS can be allocated to support MIMO transmissions. DMRS information is provided for the initial decoding requirements required for low-latency applications, but it is only occasionally used in low-speed scenarios where the channel has little change. In high mobility scenarios that track rapid changes in the channel, the transmission rate of the DMRS can be increased (referred to as "additional DMRS").

[0099] For example, in a V2X communication system, sidelink communications between UEs (e.g., V-UE 160, UE 204) may occur while one or both UEs are moving. For example, a first UE may be traveling at a first speed and may attempt to send or receive communications with an adjacent UE traveling at a different speed (e.g., via a sidelink transmission). In some cases, the speed difference between the UEs may range from a few kilometers per hour (kmph) to approximately 500kmph. When the relative speed between the UEs is high, more frequent DMRS transmissions in the time domain are required to recover the channel. However, when the relative speed is low, more frequent DMRS transmissions are just additional overhead, which results in reduced spectral efficiency. Therefore, it would be beneficial to use different DMRS patterns with different time densities for sidelink data transmission in V2X communications. It may also be beneficial if the transmitting UE can dynamically indicate the DMRS pattern.

[0100] In addition, multiple time slot formats may be needed for side link communications. For example, some time slots may have OFDM symbols assigned for side link HARQ feedback (or another signal / channel) transmission, while other time slots may be dedicated to side link communications. In another example, some time slots may have fewer OFDM symbols that can be used or assigned for side link transmission. Therefore, the number of OFDM symbols that can be used for side link data transmission (including DMRS) can be different due to the type of time slot.

[0101] Therefore, the present disclosure provides techniques for indicating and interpreting DMRS patterns for sidelink communications. Specifically, the present disclosure provides techniques for selecting a DMRS pattern (e.g., dynamically) and using simplified signaling to indicate the DMRS pattern regardless of the slot format. In this way, the transmitting UE and the receiving UE will have the same understanding of the DMRS pattern being used while maintaining low signaling overhead.

[0102] The following is from a receiver UE (eg, referenced above Figure 1-4 Summary of certain aspects from the perspective of any UE described herein. To receive a sidelink transmission (e.g., a sidelink data transmission on a sidelink shared channel), a receiver UE may determine, based at least on a format of the time slot (e.g., whether HARQ feedback symbols are included), a DMRS pattern or a set of DMRS patterns for a time slot having a sidelink transmission. The receiver UE may then use the determined DMRS pattern to receive the sidelink transmission in the time slot. When multiple DMRS patterns are determined for the time slot format, the receiver UE may determine the DMRS pattern based on an indication from a transmitter UE (e.g., in sidelink control information (SCI) associated with the sidelink transmission).

[0103] The following is from the transmitter UE (eg, referenced above Figure 1-4 A summary of certain aspects is provided herein from the perspective of any UE described herein. To send a side link transmission, a transmitter UE may determine a DMRS pattern for a time slot with a side link transmission based at least on a format of the time slot (e.g., whether HARQ feedback symbols are included). The transmitter UE may then send a DMRS in the time slot based on the determined DMRS pattern. Alternatively, the transmitter UE may first determine a set of DMRS patterns based on the format of the time slot, and then determine the DMRS pattern from the set of DMRS patterns. It should be noted that when there are multiple candidate DMRS patterns (e.g., a set of DMRS patterns), the transmitter UE may select a DMRS pattern and send an indication to the receiver UE to indicate the selected DMRS pattern (e.g., indicated in an SCI associated with the side link transmission).

[0104] For different DMRS patterns in a set, at least one of the following may be different: (1) the number of OFDM symbols allocated to DMRS, (2) the location of the OFDM symbols allocated to DMRS, or (3) the DMRS type (i.e., type A or type B). In one example, DMRS types A and B may have different locations and / or densities of DMRS tones / subcarriers in a DMRS symbol. For different time slot formats, at least one of the following may be different: (1) the number of OFDM symbols available for sidelink transmission, (2) the number of OFDM symbols available for sidelink data channel transmission, (3) the starting position of the OFDM symbols available for sidelink transmission, (4) the starting position of the OFDM symbols available for sidelink data channel transmission, (5) the ending position of the OFDM symbols available for transmission on the sidelink, or (6) the ending position of the OFDM symbols available for the sidelink data channel.

[0105] A UE performing sidelink data transmission / reception may have a (pre) configured subcarrier spacing (SCS) (or carrier frequency) for the sidelink. In one aspect, the determination of one or a group of DMRS patterns for sidelink transmission may also be based on the SCS or frequency range (FR) of the sidelink. This means that for different SCSs or FRs, one or a group of DMRSs determined for sidelink transmission may be different for the same time slot format (see Table 1). The reason is that the larger the SCS, the shorter the duration of the OFDM symbol, so fewer DMRSs may be required. For example, for a certain SCS (e.g., 30kHz) or a certain FR (e.g., FR1), one or a group of DMRS patterns may be (pre) configured for each time slot format. Therefore, depending on the SCS (and / or FR) and the time slot format (e.g., whether HARQ feedback symbols are included), one or a group of DMRS patterns may be used in a certain time slot.

[0106] Two or more slot formats may be used on the side link. The slot format may be based on the number of OFDM symbols available for side link data transmission. For example, in a slot containing OFDM symbols allocated for HARQ feedback (or simply "feedback") transmission, fewer OFDM symbols may be available for side link data transmission. In one aspect, a set of DMRS patterns may be (pre-)configured for each slot format. Thus, the DMRS patterns included in the set of DMRS patterns may be different for different slot formats. As described above, the DMRS patterns in the set may also depend on the SCS or FR of the side link.

[0107] With reference in more detail to the use of multiple (a set of) DMRS patterns for a particular slot format, a UE (whether a transmitter or a receiver) first determines the set of DMRS patterns based on the slot format currently being used for sidelink transmission. The determination may also depend on the SCS or FR of the sidelink. If the UE is transmitting, the UE then selects a DMRS pattern from the set, transmits the DMRS in the current slot based on the DMRS pattern, and substantially simultaneously, an index value for the selected DMRS pattern may be transmitted in the SCI. In one aspect, the DMRS pattern may be selected from the set based on the relative speed of the UE, (statistical) HARQ feedback, etc. If the UE is receiving, the UE receives a DMRS index value (e.g., in the SCI) from the transmitting UE, determines the DMRS pattern based on the index and the (pre-) configured DMRS pattern set, and then receives the sidelink transmission in the slot based on the determined DMRS pattern.

[0108] In one aspect, instead of (pre-)configuring a set of DMRS patterns for each slot format, only one DMRS pattern may be (pre-)configured for each slot format. A different DMRS pattern may be used for each slot format. One DMRS pattern for each slot format may also depend on the SCS or FR of the side link. That is, for the same slot format, the (pre-)configured DMRS pattern may be different for different SCS or FR.

[0109] Referring to the use of one DMRS pattern per slot format in more detail, the UE (whether a transmitter or a receiver) first determines the DMRS pattern based on the slot format currently being used for the side link transmission. The determination may also depend on the SCS or FR of the side link. If the UE is transmitting, the UE transmits the DMRS in the current slot based on the determined DMRS pattern. If the UE is receiving, the UE receives the side link transmission in the slot based on the determined DMRS pattern.

[0110] In one aspect, the various DMRS patterns described herein may be configured to the UE by a serving base station or some other network entity. Alternatively, the UE may be pre-configured by, for example, an original equipment manufacturer (OEM) so that the UE may communicate on a side link without the involvement of a network entity.

[0111] Figure 6 According to aspects of the present disclosure, example DMRS pattern sets for two different time slot formats are shown. Figure 6 In the example of , the side link has two time slot formats, one for side link time slots with HARQ feedback resources (i.e., with symbols allocated for HARQ feedback), and the other for side link time slots without HARQ feedback resources (i.e., without symbols allocated for HARQ feedback). For normal (or extended) CP, a side link time slot without HARQ feedback resources can have 12, 13, or 14 (or 10, 11, or 12 for extended CP) OFDM symbols available for side link data channel transmission. A side link time slot with HARQ feedback resources can have 9 or 10 (or 7 or 8 for extended CP) OFDM symbols available for side link data channel transmission.

[0112] exist Figure 6In the example of , two sets of DMRS patterns have been (pre-)configured, with each of the two time slot formats using one set of DMRS patterns. The DMRS pattern set 610 for regular time slots (i.e., side link time slots without HARQ feedback resources) includes three DMRS patterns. The DMRS pattern set 650 for HARQ feedback time slots (e.g., physical side link feedback channel (PSFCH) time slots) includes two DMRS patterns. The DMRS patterns in each set have an index. For the DMRS pattern set 610, the indexes of the three patterns can be "0", "1", and "2". For the DMRS pattern set 650, the indexes of the two patterns can be "0" and "1".

[0113] In an example operation, when the transmitter UE determines that the current time slot is a regular time slot (ie, no HARQ feedback), it selects one of the three patterns from the DMRS pattern set 610. Figure 6 In the example of , the first mode (labeled as "mode 1") of the DMRS pattern set 610 has two OFDM symbols allocated to DMRS, the second mode (labeled as "mode 2") has three OFDM symbols allocated to DMRS, and the third mode (labeled as "mode 3") has four OFDM symbols allocated to DMRS. Therefore, for example, the transmitter UE can select the third mode for high-speed scenarios and the first mode for low-speed scenarios. The transmitter UE then sends the index value ("0", "1" or "2") of the selected DMRS mode to the receiver UE in the SCI, and uses the selected DMRS mode for side link transmission in the current time slot.

[0114] When the transmitter UE determines that the time slot is a HARQ feedback time slot, it selects one of two patterns from the DMRS pattern set 650. Figure 6 In the example of , the first mode (labeled as "mode 1") of the DMRS pattern set 650 has two OFDM symbols allocated to the DMRS, and the second mode (labeled as "mode 2") has three OFDM symbols allocated to the DMRS. Therefore, as an example, the transmitter UE can select the second mode for a high-speed scenario and the first mode for a low-speed scenario. The transmitter UE then sends the index value ("0" or "1") of the selected DMRS mode in the SCI to the receiver UE, and uses the selected DMRS mode for side link transmission in the current time slot.

[0115] When the receiver UE receives a DMRS pattern index value of "0" in the SCI, for example, from the transmitter UE, if the current time slot is a regular time slot, it determines that the transmitter UE has selected the first pattern in the DMRS pattern set 610. Alternatively, if the time slot is a HARQ feedback time slot, the receiver UE determines that the transmitter UE has selected the first pattern in the DMRS pattern set 650. In one example, the DMRS pattern index value may be specified for a certain FR (e.g., FR1) or SCS (e.g., 30 kHz). Figure 6 For different FRs or SCSs, another set of DMRS patterns may be specified.

[0116] Figure 7 According to aspects of the present disclosure, example DMRS pattern sets for two different time slot formats are shown. Figure 7 In the example of , two time slot formats for side link communication are specified, one for side link time slots with HARQ feedback resources and the other for side link time slots without HARQ feedback resources. Figure 6 As described, for a normal (or extended) CP, a side link time slot without HARQ feedback resources may have 12, 13 or 14 (or 10, 11 or 12, for extended CP) OFDM symbols available for side link data channel transmission. A side link time slot with HARQ feedback resources may have 9 or 10 (or 7 or 8, for extended CP) OFDM symbols available for side link data channel transmission.

[0117] exist Figure 7 In the example of , two sets of DMRS patterns have been (pre-)configured, and each of the two time slot formats uses a set of DMRS patterns. The DMRS pattern set 710 for the regular time slot includes two DMRS patterns, and the DMRS pattern set 750 for the HARQ feedback time slot also includes two DMRS patterns. The DMRS patterns in each set have an index. For the DMRS pattern set 710, the indexes of the two patterns can be "0" and "1", and for the DMRS pattern set 750, the indexes of the two patterns can also be "0" and "1".

[0118] In an example operation, when the transmitter UE determines that the current time slot is a regular time slot, it selects one of the two patterns from the DMRS pattern set 710. The transmitter UE then sends the index value ("0" or "1") of the selected DMRS pattern to the receiver UE in the SCI, and uses the selected DMRS pattern for side link transmission in the current time slot. Alternatively, when the transmitter UE determines that the time slot is a HARQ feedback time slot, it selects one of the two patterns from the DMRS pattern set 750. The transmitter UE then sends the index value ("0" or "1") of the selected DMRS pattern to the receiver UE in the SCI, and uses the selected DMRS pattern for side link transmission in the current time slot.

[0119] When the receiver UE receives a DMRS pattern index value of "0" from the transmitter UE in the SCI, for example, if the current time slot is a regular time slot, it determines that the transmitter UE has selected the first pattern in the DMRS pattern set 710. Alternatively, if the time slot is a HARQ feedback time slot, the receiver UE determines that the transmitter UE has selected the first pattern in the DMRS pattern set 750. In one example, the DMRS pattern index value may be specified for a certain FR (e.g., FR1) or SCS (e.g., 30 kHz). Figure 7 For different FRs or SCSs, another set of DMRS patterns may be specified.

[0120] Figure 8 According to aspects of the present disclosure, example DMRS patterns for two different time slot formats are shown. Figure 8 In the example of , the side link has two time slot formats, one for the side link time slot with HARQ feedback resources and the other for the side link time slot without HARQ feedback resources. Figure 6 As described, for a normal (or extended) CP, a side link time slot without HARQ feedback resources may have 12, 13 or 14 (or 10, 11 or 12, for extended CP) OFDM symbols available for side link data channel transmission. A side link time slot with HARQ feedback resources may have 9 or 10 (or 7 or 8, for extended CP) OFDM symbols available for side link data channel transmission.

[0121] exist Figure 8 In the example of , two sets of DMRS patterns have been (pre-)configured, one set of DMRS patterns used for each of the two slot formats. Figure 8As shown in , each time slot format type uses a single DMRS pattern, which may be applicable to a specific SCS or FR. DMRS pattern 810 is used for regular time slots and DMRS pattern 850 is used for HARQ feedback time slots. Because there is only one DMRS pattern for each time slot format, an index value for the DMRS pattern is not required. Instead, when the transmitter UE determines that the current time slot is a regular time slot, it simply uses DMRS pattern 810 for side link transmission in the current time slot. Alternatively, when the transmitter UE determines that the time slot is a HARQ feedback time slot, DMRS pattern 850 is used for side link transmission in the current time slot.

[0122] On the receiver UE side, if the current time slot is a regular time slot, the receiver UE determines that the DMRS pattern 810 applies to the time slot. However, if the time slot is a HARQ feedback time slot, the receiver UE determines that the DMRS pattern 850 applies to the time slot. In one example, a DMRS pattern 850 may be specified for a certain FR (e.g., FR1) or SCS (e.g., 30 kHz). Figure 8 For different FRs or SCSs, another set of DMRS patterns may be specified.

[0123] Fig. 9 According to aspects of the present disclosure, example DMRS pattern sets for two different time slot formats are shown. Fig. 9 In the example of , the side link has two time slot formats, one for the side link time slot with HARQ feedback resources and the other for the side link time slot without HARQ feedback resources. Fig. 9 In the example of , extended CP is used, which means that a time slot without HARQ feedback resources has 10, 11 or 12 OFDM symbols available for side link data channel transmission. A side link time slot with HARQ feedback resources can have 7 or 8 OFDM symbols available for side link data channel transmission.

[0124] exist Fig. 9 In the example of , two sets of DMRS patterns have been (pre-)configured, and each of the two time slot formats uses a set of DMRS patterns. The DMRS pattern set 910 for regular time slots includes two DMRS patterns, and the DMRS pattern set 950 for HARQ feedback time slots also includes two DMRS patterns. The DMRS patterns in each set have an index. For the DMRS pattern set 910, the indexes of the two patterns can be "0" and "1", and for the DMRS pattern set 950, the indexes of the two patterns can also be "0" and "1".

[0125] In an example operation, when the transmitter UE determines that the current time slot is a regular time slot, it selects one of the two patterns from the DMRS pattern set 910. The transmitter UE then sends the index value ("0" or "1") of the selected DMRS pattern to the receiver UE in the SCI, and uses the selected DMRS pattern for side link transmission in the current time slot. Alternatively, when the transmitter UE determines that the time slot is a HARQ feedback time slot, it selects one of the two patterns from the DMRS pattern set 950. The transmitter UE then sends the index value ("0" or "1") of the selected DMRS pattern to the receiver UE in the SCI, and uses the selected DMRS pattern for side link transmission in the current time slot.

[0126] When the receiver UE receives a DMRS pattern index value of "0" from the transmitter UE in the SCI, for example, if the current time slot is a regular time slot, it determines that the transmitter UE has selected the first pattern in the DMRS pattern set 910. Alternatively, if the time slot is a HARQ feedback time slot, the receiver UE determines that the transmitter UE has selected the first pattern in the DMRS pattern set 950. In one example, the DMRS pattern index value may be specified for a certain FR (e.g., FR1) or SCS (e.g., 30 kHz). Fig. 9 For different FRs or SCSs, another set of DMRS patterns may be specified.

[0127] Fig.10 According to aspects of the present disclosure, example DMRS patterns for two different time slot formats are shown. Fig.10 In the example of FIG. 1 , a side link is established between two UEs (eg, as shown in the above reference Figure 3 The STA described herein has two time slot formats, one for side link time slots with HARQ feedback resources (on PSFCH) and the other for side link time slots without HARQ feedback resources.

[0128] exist Fig.10 In the example of , two DMRS patterns have been (pre-)configured, and each of the two time slot formats uses a set of DMRS patterns. DMRS pattern 1010 is used for regular time slots and DMRS pattern 1050 is used for HARQ feedback time slots. Because there is only one DMRS pattern per time slot format, no index value is required to indicate the DMRS pattern. Instead, when the transmitter UE determines that the current time slot is a regular time slot, it simply uses DMRS pattern 1010 for side link transmission in the current time slot. Alternatively, when the transmitter UE determines that the time slot is a HARQ feedback time slot, it uses DMRS pattern 1050 for side link transmission in the current time slot.

[0129] At the receiver UE side, if the current time slot is a regular time slot, the receiver UE determines that the DMRS pattern 1010 is applied to the time slot. However, if the time slot is a HARQ feedback time slot, the receiver UE determines that the DMRS pattern 1050 is applicable to the time slot.

[0130] exist Fig.10 In the example, for the DMRS pattern (pre) configuration and determination, the SCS and / or FR of the side link can be considered. For example, the side link can be deployed on FR1 and FR2 at the same time, so that FR can be taken into account. To give a specific example, for FR1, Figure 8 The two modes shown in can be (pre-)configured, and for FR2, Fig.10 The two patterns shown in can be (pre)configured. Thus, the UE determines the DMRS pattern based on the FR it is transmitting or receiving and the determined slot format (i.e., with or without HARQ feedback). As another example, the sidelinks may be deployed on different subcarriers, and thus the SCS may be taken into account in the DMRS pattern (pre)configuration and determination. As a specific example, for one SCS, Figure 8 The two modes shown in can be (pre-)configured and for another SCS, Fig.10 The two modes shown in may be (pre-)configured.

[0131] As described above, the slot format may be determined / defined by whether the slot includes HARQ feedback. The slot format may also be determined / defined by the number of OFDM symbols available for transmission of the sidelink data channel, or the number of OFDM symbols allocated to the sidelink. For example, two slot formats may be specified, one for slots with more than nine (or other number) OFDM symbols available for the sidelink data channel, and another for slots with nine (or other number) or fewer OFDM symbols available for the sidelink data channel.

[0132] Fig.11 In accordance with aspects of the present disclosure, a method 1100 of wireless communication is shown. In one aspect, the method 1100 may be performed by a transmitter UE (eg, any of the UEs described herein).

[0133] At 1110, the UE determines a first DMRS pattern for a first time slot, the first time slot being allocated for data transmission on a side link between a transmitter UE and a receiver UE (e.g., any UE described herein). In one aspect, the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats. In one aspect, the first time slot format specifies that at least a first number of OFDM symbols are available for side link transmission. In one aspect, operation 1110 may be performed by transceiver 404, processing system 410, memory 414, and / or side link manager 470, any or all of which may be considered a means for performing the operation.

[0134] At 1120, the UE transmits a DMRS to the receiver UE in the first time slot according to the first DMRS pattern. In one aspect, operation 1120 may be performed by transceiver 404, processing system 410, memory 414, and / or side link manager 470, any or all of which may be considered a means for performing the operation.

[0135] Fig.12 In accordance with aspects of the present disclosure, a method 1200 of wireless communication is shown. In one aspect, the method 1200 may be performed by a receiver UE (eg, any of the UEs described herein).

[0136] At 1210, the UE determines a first DMRS pattern for a first time slot, the first time slot being allocated for data reception on a side link between a receiver UE and a transmitter UE (e.g., any UE described herein). In one aspect, the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats. In one aspect, the first time slot format specifies that at least a first number of OFDM symbols are available for side link transmission. In one aspect, operation 1210 may be performed by transceiver 404, processing system 410, memory 414, and / or side link manager 470, any or all of which may be considered a means for performing the operation.

[0137] At 1220, the UE receives a DMRS from the transmitter UE in the first time slot according to the first DMRS pattern. In one aspect, operation 1220 may be performed by the transceiver 404, the processing system 410, the memory 414, and / or the side link manager 470, any or all of which may be considered a means for performing the operation.

[0138] It should be appreciated that a technical advantage of methods 1100 and 1200 is that signaling overhead is reduced by selecting a DMRS pattern and using simplified signaling to indicate the DMRS pattern regardless of the time slot format.

[0139] It will be understood by those skilled in the art that information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0140] In addition, it should be understood by those skilled in the art that the various exemplary logic blocks, modules, circuits, and algorithm steps described in conjunction with the aspects disclosed herein can be implemented as electronic hardware, computer software, or a combination of the two. In order to clearly represent this interchangeability between hardware and software, the above various exemplary components, blocks, modules, circuits, and steps are generally described around their functions. Whether such functions are implemented as hardware or software depends on the specific application and the design constraints imposed on the entire system. A skilled technician can implement the described functions in an alternative manner for each specific application, but such implementation decisions should not be interpreted as departing from the scope of protection of the present invention.

[0141] A general purpose processor, digital signal processor (DSP), ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware components or any combination thereof for performing the functions described herein may implement or perform the various exemplary logic blocks, modules and circuits described in conjunction with the aspects disclosed herein. A general purpose processor may be a microprocessor, or alternatively, the processor may be any conventional processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such structure.

[0142] The methods, sequences and / or algorithms described in conjunction with the aspects disclosed herein may be directly embodied as hardware, software modules executed by a processor, or a combination of the two. The software module may be located in a random access memory (RAM), a flash memory, a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium may be connected to a processor so that the processor can read information from the storage medium and write information to the storage medium. Alternatively, the storage medium may also be a component of a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., UE). Alternatively, the processor and the storage medium may reside in a user terminal as discrete components.

[0143] In one or more exemplary aspects, the functions described can be implemented with hardware, software, firmware, or any combination thereof. When implemented with software, the functions can be stored on a computer-readable medium, or sent by one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein the communication media include any media that helps to transmit a computer program from one place to another. The storage medium can be any available medium that a computer can access. For example, but not limited to, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store a desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition, any connection can be appropriately referred to as a computer-readable medium. For example, if the software is transmitted from a website, server or other remote source using a coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, wireless and microwave, then the coaxial cable, optical fiber cable, twisted pair, DSL, or wireless technologies such as infrared, wireless and microwave are included in the definition of the computer-readable medium. As used herein, disks and optical discs include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and optical discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of protection of computer-readable media.

[0144] Although the above disclosure shows exemplary aspects of the present disclosure, it should be noted that various changes and modifications may be made to the present application without departing from the scope of protection of the present disclosure as defined in the appended claims. The steps and / or actions of the method claims according to the various aspects of the present disclosure described herein do not need to be performed in any particular order. In addition, although the constituent elements of the present disclosure are described or claimed in the singular, the plural form is contemplated unless it is explicitly stated to be limited to the singular.

Claims

1. A method of wireless communication performed by a transmitter user equipment UE (104, 204, 302), comprising: determining (1110) a first demodulation reference signal (DMRS) pattern for a first time slot allocated for transmission on a side link (242, 330) between the transmitter UE (104, 204, 302) and the receiver UE (104, 204, 304), wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, wherein the two or more time slot formats include at least one time slot format representing a side link time slot having a hybrid automatic repeat request (HARQ) feedback resource and at least one other time slot format representing a side link time slot without a HARQ feedback resource, and wherein a first number of orthogonal frequency division multiplexing (OFDM) symbols specified by the first time slot format is based on: whether a side link transmission based on the first time slot format includes a HARQ feedback resource; sending an index value of the first DMRS pattern to the receiver UE (104, 204, 304) in sidelink control information SCI; and A DMRS is transmitted (1120) to the receiver UE (104, 204, 304) in the first time slot according to the first DMRS pattern.

2. The method according to claim 1, wherein: The first DMRS pattern is one of a first set of DMRS patterns specified for the first slot format.

3. The method according to claim 2, further comprising: determining a second DMRS pattern for a second time slot allocated for transmission on the sidelink (242, 330), wherein the second DMRS pattern is determined based at least on the second time slot having the first time slot format; and According to the second DMRS pattern, a DMRS is transmitted to the receiver UE (104, 204, 304) in the second time slot.

4. The method according to claim 2, wherein: The number of OFDM symbols allocated to DMRS, the location of OFDM symbols allocated to DMRS, the DMRS type, or any combination thereof is different for each DMRS pattern in the first set of DMRS patterns.

5. The method according to claim 1, further comprising: determining a second DMRS pattern for a second time slot allocated for transmission on the side link (242, 330), wherein the second DMRS pattern is determined based at least on the second time slot having a second time slot format of the two or more time slot formats; and According to the second DMRS pattern, a DMRS is transmitted to the receiver UE (104, 204, 304) in the second time slot.

6. The method according to claim 5, wherein: The second DMRS pattern is one of a second set of DMRS patterns specified for the second slot format.

7. The method according to claim 5, wherein: The first time slot format comprises a conventional time slot format having no OFDM symbols assigned for the sidelink feedback, and The second slot format comprises a feedback slot format having OFDM symbols assigned for the sidelink feedback.

8. The method according to claim 5, wherein: The number of OFDM symbols available for transmission on the side link (242, 330), the starting position of the OFDM symbols available for transmission on the side link (242, 330), the starting position of the OFDM symbols available for transmission on the side link data channel, the ending position of the OFDM symbols available for transmission on the side link (242, 330), the ending position of the OFDM symbols available for transmission on the side link data channel, or any combination thereof are different between the first time slot format and the second time slot format.

9. The method according to claim 1, wherein: Determining the first DMRS pattern is also based on a subcarrier spacing SCS, a frequency range of the sidelink (242, 330), or both.

10. A method of wireless communication performed by a receiver user equipment UE (104, 204, 304), comprising: determining (1210) a first demodulation reference signal (DMRS) pattern for a first time slot allocated for data reception on a side link (242, 330) between the receiver UE (104, 204, 304) and the transmitter UE (104, 204, 302), wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, wherein the two or more time slot formats include at least one time slot format representing a side link time slot with a hybrid automatic repeat request (HARQ) feedback resource and at least one other time slot format representing a side link time slot without a HARQ feedback resource, and wherein a first number of orthogonal frequency division multiplexing (OFDM) symbols specified by the first time slot format is based on: whether a side link transmission based on the first time slot format includes a HARQ feedback resource; receiving an index value of the first DMRS pattern from the transmitter UE (104, 204, 302) in sidelink control information SCI; determining the first DMRS pattern based on the index value; and A DMRS is received (1220) from the transmitter UE (104, 204, 302) in the first time slot according to the first DMRS pattern.

11. A transmitter user equipment UE (104, 204, 302), comprising: Unit for determining a first demodulation reference signal (DMRS) pattern for a first time slot allocated for transmission on a side link (242, 330) between the transmitter UE (104, 204, 302) and the receiver UE (104, 204, 304), wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, wherein the two or more time slot formats include at least one time slot format representing a side link time slot with hybrid automatic repeat request (HARQ) feedback resources and at least one other time slot format representing a side link time slot without HARQ feedback resources, and wherein a first number of orthogonal frequency division multiplexing (OFDM) symbols specified by the first time slot format is based on: whether a side link transmission based on the first time slot format includes HARQ feedback resources; means for sending an index value of the first DMRS pattern to the receiver UE (104, 204, 304) in sidelink control information SCI; and Means for sending a DMRS to the receiver UE (104, 204, 304) in the first time slot according to the first DMRS pattern.

12. A receiver user equipment UE (104, 204, 304), comprising: Unit for determining a first demodulation reference signal (DMRS) pattern for a first time slot allocated for data reception on a side link (242, 330) between the receiver UE (104, 204, 304) and the transmitter UE (104, 204, 302), wherein the first DMRS pattern is determined based at least on the first time slot having a first time slot format of two or more time slot formats, wherein the two or more time slot formats include at least one time slot format representing a side link time slot with hybrid automatic repeat request (HARQ) feedback resources and at least one other time slot format representing a side link time slot without HARQ feedback resources, and wherein a first number of orthogonal frequency division multiplexing (OFDM) symbols specified by the first time slot format is based on: whether a side link transmission based on the first time slot format includes HARQ feedback resources; means for receiving an index value of the first DMRS pattern from the transmitter UE (104, 204, 302) in sidelink control information SCI; means for determining the first DMRS pattern based on the index value; and Means for receiving, via the at least one transceiver, a DMRS from the transmitter UE (104, 204, 302) in the first time slot according to the first DMRS pattern.

13. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to perform the method according to any one of claims 1 to 9 or 10.

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