Simplified SL-SS (Sidelink Synchronization Signal) transmission of S-SSB (Sidelink Synchronization Signal Block) on demand

Abstract

A method of wireless communication by a transmitting sidelink user equipment (UE), comprising: transmitting a sidelink synchronization signal (SL‑SS) within a sidelink synchronization signal block (S‑SSB). The SL‑SS has an SL‑SS pattern with a reduced number of physical sidelink broadcast channel (PSBCH) symbols, the reduced number of PSBCH symbols may be zero PSBCH symbols. The method further comprises: receiving a transmission according to the SL‑SS. The SL‑SS may be transmitted at a different time and / or frequency than a legacy SL‑SS.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 324,951, filed on May 19, 2021, entitled “LITE SL-SS (SIDELINK SYNCHRONIZATION SIGNAL) TRANSMISSION FOR ON DEMAND S-SSB (SIDELINK SYNCHRONIZATION SIGNAL BLOCK)”, which claims the benefit of U.S. Provisional Patent Application No. 63 / 029,280, filed on May 22, 2020, entitled “LITE SL-SS (SIDELINK SYNCHRONIZATION SIGNAL) TRANSMISSION FOR ON DEMAND S-SSB (SIDELINK SYNCHRONIZATION SIGNAL BLOCK)”, the disclosures of which are expressly incorporated by reference in their entireties. Technical Field

[0003] Aspects of the present disclosure relate generally to wireless communications, and more particularly to techniques and apparatus for reduced SL-SS (sidelink synchronization signal) transmission for on-demand S-SSB (sidelink synchronization signal block). Background Art

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide common protocols that enable different wireless devices to communicate at city, national, regional and even global levels. An example telecommunication standard is the fifth generation (5G) New Radio (NR). 5G NR is part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements and other requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)). 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC) and ultra-reliable low latency communications (URLLC). Some aspects of 5G NR can be based on the fourth generation (4G) long term evolution (LTE) standard. There is a need for further improvement of 5G NR technology. These improvements can also be applied to other multiple access technologies and telecommunication standards that adopt these technologies.

[0006] The wireless communication system may include or provide support for various types of communication systems, such as vehicle-related communication systems (e.g., vehicle-to-everything (V2X) communication systems). The vehicle-related communication system may be used by the vehicle to increase safety and help prevent collisions of the vehicle. Information about severe weather, nearby accidents, road conditions, and / or other information may be transmitted to the driver via the vehicle-related communication system. In some cases, sidelink user equipment (UE) such as vehicles may communicate directly with each other using device-to-device (D2D) communications over D2D wireless links. These communications may be referred to as sidelink communications.

[0007] As the demand for sidelink communications increases, different V2X communication systems compete for the same wireless communication resources. In addition, some sidelink UEs may be power-limited. Therefore, there is a need to improve the efficiency of sidelink wireless communications. Summary of the invention

[0008] In various aspects of the present disclosure, a method of wireless communication performed by a transmitting sidelink user equipment (UE) includes transmitting a sidelink synchronization signal (SL-SS) within a sidelink synchronization signal block (S-SSB). The SL-SS has an SL-SS pattern with a reduced number of physical sidelink broadcast channel (PSBCH) symbols. The method also includes receiving a transmission according to the SL-SS.

[0009] Other aspects of the present disclosure relate to an apparatus for wireless communication at a transmitting sidelink user equipment (UE), the apparatus having a processor, a memory coupled to the processor, and instructions stored in the memory. When the instructions are executed by the processor, the apparatus transmits a sidelink synchronization signal (SL-SS) within a sidelink synchronization signal block (S-SSB). The SL-SS has an SL-SS pattern with a reduced number of physical sidelink broadcast channel (PSBCH) symbols. The apparatus also receives a transmission based on the SL-SS.

[0010] In another aspect of the present disclosure, an apparatus for wireless communication at a user equipment (UE) includes means for transmitting a sidelink synchronization signal (SL-SS) within a sidelink synchronization signal block (S-SSB). The SL-SS has an SL-SS pattern with a reduced number of physical sidelink broadcast channel (PSBCH) symbols. The apparatus also includes means for receiving a transmission according to the SL-SS.

[0011] Aspects generally include methods, apparatuses, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and processing systems as described herein with reference to and as illustrated in the drawings and description.

[0012] The features and technical advantages of the examples according to the present disclosure have been outlined quite broadly above so that the subsequent detailed description can be better understood. Additional features and advantages will be described. The disclosed concepts and specific examples can be easily used as the basis for modifying or designing other structures for the same purpose of implementing the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The features of the disclosed concepts, their organization and method of operation, and the associated advantages will be better understood from the following description when considered in conjunction with the accompanying drawings. Each figure is provided for the purpose of illustration and description, and not as a definition of the limitations of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order that the features of the present disclosure recorded above can be understood in detail, a more specific description briefly summarized above may be made by reference to various aspects, some of which are shown in the accompanying drawings. However, it is to be noted that the drawings only illustrate certain typical aspects of the present disclosure and are therefore not to be considered as limiting the scope thereof, as the description may admit of other equivalent aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0014] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0015] Figure 2A , Figure 2B , Figure 2C and Figure 2D 2 are diagrams showing examples of a first fifth generation (5G) new radio (NR) frame, a downlink (DL) channel within a 5G NR subframe, a second 5G NR frame, and an uplink (UL) channel within a 5G NR subframe, respectively.

[0016] Figure 3 is a block diagram illustrating an example of a base station in an access network communicating with a user equipment (UE).

[0017] Figure 4 is a diagram illustrating an example of a device-to-device (D2D) system including vehicle-to-everything (V2X) communications according to various aspects of the present disclosure.

[0018] Figure 5 is a block diagram illustrating an example of a vehicle-to-everything (V2X) system with a roadside unit (RSU) according to aspects of the present disclosure.

[0019] Figure 6 is a block diagram illustrating an orthogonal frequency division multiplexing (OFDM) symbol of a legacy sidelink synchronization signal block (S-SSB) in accordance with aspects of the present disclosure.

[0020] Figure 7 is a block diagram of a style of a simplified sidelink synchronization signal block (S-SSB) according to various aspects of the present disclosure.

[0021] Figure 8 It is a diagram showing various aspects of the present disclosure. Figure 7 Block diagram of a subset of the styles shown in .

[0022] Fig. 9 is a flow chart illustrating an example process performed, for example, by a sidelink user equipment according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0023] The various aspects of the present disclosure are described more fully below with reference to the accompanying drawings. However, the present disclosure can be embodied in many different forms and should not be construed as being limited to any specific structure or function presented throughout the present disclosure. On the contrary, these aspects are provided so that the present disclosure will be exhaustive and complete, and the scope of the present disclosure is fully conveyed to those skilled in the art. Based on the teachings, it should be understood by those skilled in the art that the scope of the present disclosure is intended to cover any aspect of the present disclosure disclosed, whether implemented independently of any other aspect of the present disclosure or implemented in combination with any other aspect of the present disclosure. For example, any number of aspects of the present disclosure can be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such a device or method that is practiced using other structures, functionality, or structures and functionality other than or different from the various aspects of the present disclosure described. It should be understood that any aspect of the present disclosure disclosed can be embodied by one or more elements of the claims.

[0024] Several aspects of telecommunication systems will now be presented with reference to various devices and techniques. These devices and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0025] It should be noted that while various aspects may be described using terminology generally associated with 5G and later wireless technologies, various aspects of the present disclosure may be applied to other generation-based communication systems, such as and including 3G and / or 4G technologies.

[0026] In a cellular communication network, wireless devices can typically communicate with each other via one or more network entities such as a base station or a scheduling entity. Some networks may support device-to-device (D2D) communication, which may use a direct link between devices (e.g., not through a base station, a repeater, or another node) to enable discovery of and communication with nearby devices. D2D communication may enable mesh networking and device-to-network relay functionality. Some examples of D2D technologies include Bluetooth pairing, Wi-Fi Direct, Miracast, and LTE-D. D2D communication may also be referred to as point-to-point (P2P) or sidelink communication.

[0027] D2D communications can be implemented using licensed or unlicensed frequency bands. In addition, D2D communications can avoid the overhead involved in routing to and from base stations. Therefore, D2D communications can improve throughput, reduce latency, and / or increase energy efficiency. Types of D2D communications can include vehicle-to-everything (V2X) communications. V2X communications can assist autonomous vehicles in communicating with each other.

[0028] In New Radio (NR) Vehicle-to-Everything (V2X) communications, the transmitting sidelink UE and the receiving sidelink UE should be synchronized to enable communication with each other, for example, for demodulation of received data. The UEs can be synchronized via a common base station or via a synchronized base station. When the UEs are in different non-synchronized cells or one or both of the UEs are out of network coverage, the UEs synchronize with each other via a sidelink synchronization signal (SL-SS).

[0029] SL-SS is sent within the Sidelink Synchronization Signal Block (S-SSB). The signals carried within the S-SSB include the Sidelink Primary Synchronization Signal (S-PSS), the Sidelink Secondary Synchronization Signal (S-SSS), and the Physical Sidelink Broadcast Channel (PSBCH). The S-PSS, S-SSS, and PSBCH together carry information such as the source ID of the transmitting UE and synchronization information.

[0030] S-SSB transmissions may be both resource-inefficient and power-hungry. According to aspects of the present disclosure, a streamlined S-SSB (or streamlined SL-SS) achieves power savings and reduces system overhead for S-SSB transmissions. A streamlined SL-SS has a pattern with an S-PSS and / or S-SSS with a reduced number of PSBCH symbols (e.g., zero PSBCH symbols). In further aspects of the present disclosure, a sidelink UE may use the SL-SS pattern based on instructions received from a gNB (e.g., for in-coverage scenarios) or pre-configured (e.g., for out-of-coverage scenarios). Alternatively, the sidelink UE may select the SL-SS pattern itself, for example, when out of network coverage.

[0031] According to various aspects of the present disclosure, the SL-SS pattern may implicitly indicate (or be based on) information related to UE behavior. For example, the SL-SS pattern may implicitly indicate UE transmit power, UE mobility level, whether the UE is within coverage or outside coverage, etc. In other aspects of the present disclosure, the SL-SS pattern explicitly indicates information about the transmitting UE. Explicit and implicit signaling may be combined. For example, the selected pattern may implicitly indicate the transmit power, while the sidelink service set identifier (SL-SSID) indicates whether the UE is within coverage.

[0032] From the perspective of the receiving side link UE, the simplified SL-SS can have the same style as the legacy SL-SS. Alternatively, at the cost of more receiver complexity, the simplified SL-SS can be sent with a different style, at a different frequency location, with a different (e.g., reserved) SL-SSID, and / or with a different timing offset.

[0033] Figure 1 1 is a diagram showing an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell 102' (a low-power cellular base station). The macro cell includes a base station. The small cell 102' includes a femto cell, a pico cell, and a macro cell.

[0034] The base station 102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with the EPC 160 via a backhaul link 132 (e.g., an S1 interface). The base station 102 configured for 5G NR (collectively referred to as the Next Generation RAN (NG-RAN)) can interface with the core network 190 via a backhaul link 184. Among other functions, the base station 102 can perform one or more of the following functions: delivery 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, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and transmission of warning messages. The base stations 102 may communicate with each other via a backhaul link 134 (eg, an X2 interface) directly or indirectly (eg, via the EPC 160 or the core network 190). The backhaul link 134 may be wired or wireless.

[0035] 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. There may be overlapping geographic coverage areas 110. For example, a small cell 102' can have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include a home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 can include an uplink (UL) (also referred to as a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from base station 102 to UE 104. The communication link 120 can use multiple input and multiple output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link can be through one or more carriers. Base station 102 / UE 104 may use spectrum with up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) bandwidth per carrier allocated in carrier aggregation for a total of up to Yx MHz (x component carriers) for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). Component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0036] Certain UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0037] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

[0038] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may improve coverage of the access network and / or increase capacity of the access network.

[0039] Whether a small cell 102' or a large cell (e.g., a macro base station), the base station 102 can include an eNB, a gNodeB (gNB), or another type of base station. Some base stations (such as gNB 180) can operate in traditional sub-6 GHz (sub 6 GHz) spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies in communications with UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 can be referred to as a mmW base station. Extremely high frequency (EHF) is part of the radio frequency (RF) in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 mm and 10 mm. Radio waves in this band can be referred to as millimeter waves. Near mmW can extend down to frequencies of 3 GHz with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also referred to as millimeter waves. Communications using mmW / near mmW radio frequency bands (eg, 3 GHz - 300 GHz) have extremely high path loss and short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0040] Base station 180 may transmit beamformed signals in one or more transmit directions 182' to UE 104. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182". UE 104 may also transmit beamformed signals to base station 180 in one or more transmit directions. Base station 180 may receive beamformed signals from UE 104 in one or more receive directions. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit and receive directions for base station 180 may be the same or may not be the same. The transmit and receive directions for UE 104 may be the same or may not be the same.

[0041] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may distribute MBMS services to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area of ​​a broadcast specific service, and may be responsible for session management (start / stop) and for collecting Evolved Multimedia Broadcast Multicast Service (eMBMS) related charging information.

[0042] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. AMF 192 may communicate with unified data management (UDM) 196. AMF 192 is a control node that handles signaling between UE 104 and the core network 190. Typically, AMF 192 provides quality of service (QoS) processes and session management. All user Internet Protocol (IP) packets are delivered through UPF 195. UPF 195 provides UE IP address allocation and other functions. UPF 195 is connected to IP services 197. IP services 197 may include the Internet, intranet, IP multimedia subsystem (IMS), PS streaming services, and / or other IP services.

[0043] Base station 102 may also be referred to as a gNB, Node B, evolved Node B (eNB), access point, base transceiver station, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmit receive point (TRP), or some other suitable term. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similar functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, a toaster, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0044] Reference again Figure 1 In certain aspects, a sidelink UE, such as UE 104, may transmit or receive a lite SL-SS (sidelink synchronization signal) with one or more other UEs 104. UE 104 may include a lite SL-SS component 198 configured to transmit or receive a lite SL-SS without a PSBCH (physical sidelink broadcast channel).

[0045] Although the following description may focus on 5G NR, the description may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0046] Figure 2A FIG200 is a diagram showing an example of a first subframe within a 5G NR frame structure. Figure 2B FIG230 is a diagram showing an example of DL channels within a 5G NR subframe. Figure 2C Figure 250 shows an example of a second subframe within a 5G NR frame structure. Figure 2D 280 is a diagram showing an example of UL channels within a 5G NR subframe. The 5G NR frame structure can be frequency division duplex (FDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within the subcarrier set are either dedicated to DL or UL, or can be time division duplex (TDD), where for a particular set of subcarriers (carrier system bandwidth), subframes within the subcarrier set are dedicated to both DL and UL. Figure 2A , Figure 2C In the example provided, the 5G NR frame structure is assumed to be TDD, subframe 4 is configured with slot format 28 (primarily DL), where D is DL, U is UL, and X is flexible between DL / UL, and subframe 3 is configured with slot format 34 (primarily UL). Although subframes 3 and 4 are shown using slot formats 34 and 28, respectively, any particular subframe can be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mix of DL, UL and flexible symbols. The UE is configured with a slot format (dynamically configured through DL control information (DCI) or semi-statically / statically configured through radio resource control (RRC) signaling) through the received slot format indicator (SFI). Note that the description below also applies to the 5G / NR frame structure as TDD.

[0047] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include a mini-slot, which may include 7, 4, or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbol on the DL may be a cyclic prefix (CP) orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbol. The symbol on the UL may be a CP-OFDM symbol (for high throughput scenarios) or a discrete Fourier transform (DFT) spread OFDM (DFT-S-OFDM) symbol (also known as a single carrier frequency division multiple access (SC-FDMA) symbol) (for power-limited scenarios; limited to single stream transmission). The number of time slots within a subframe is based on the time slot configuration and parameter set (numerology). For slot configuration 0, different parameter sets μ0 to 5 allow 1, 2, 4, 8, 16 and 32 slots per subframe, respectively. For slot configuration 1, different parameter sets 0 to 2 allow 2, 4 and 8 slots per subframe, respectively. Accordingly, for slot configuration 0 and parameter set μ, there are 14 symbols / slot and 2μ slots / subframe. The subcarrier spacing and symbol length / duration are functions of the parameter set. The subcarrier spacing can be equal to 2^μ*15kHz, where μ is parameter set 0 to 5. Thus, parameter set μ=0 has a subcarrier spacing of 15kHz, and parameter set μ=5 has a subcarrier spacing of 480kHz. The symbol length / duration is negatively correlated with the subcarrier spacing. FIG. 2A to FIG. 2D An example is provided for slot configuration 0 with 14 symbols per slot and parameter set μ=0 with 1 slot per subframe. The subcarrier spacing is 15 kHz and the symbol duration is approximately 66.7 μs.

[0048] The resource grid may represent a frame structure. Each slot includes a resource block (RB) (also referred to as a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a plurality of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0049] like Figure 2A As shown, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) (indicated as Rx for a particular configuration, where 100x is the port number, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS) for channel estimation performed at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0050] Figure 2B Examples of various DL channels within a subframe of a frame are shown. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of a frame. The PSS is used by UE 104 to determine subframe / symbol timing and physical layer identification. The secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of a frame. The SSS is used by the UE to determine the physical layer cell identification group number and radio frame timing. Based on the physical layer identification and the physical layer cell identification group number, the UE may determine the physical cell identifier (PCI). Based on the PCI, the UE may determine the location of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) may be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth and the system frame number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as a System Information Block (SIB), and paging messages.

[0051] like Figure 2C As shown, some of the REs carry DM-RS for channel estimation performed at the base station (indicated as R for one particular configuration, but other DM-RS configurations are possible). The UE can send DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS can be sent in the first one or two symbols of the PUSCH. The PUCCH DM-RS can be sent in different configurations, depending on whether a short PUCCH or a long PUCCH is sent, and on the specific PUCCH format used. Although not shown, the UE can send a sounding reference signal (SRS). The SRS can be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0052] Figure 2DExamples of various UL channels within a subframe of a frame are shown. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), and hybrid automatic repeat request (HARQ) acknowledgement / negative acknowledgement (ACK / NACK) feedback. The PUSCH carries data and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0053] In some aspects, the transmitting side link user equipment 350 may include means for transmitting, means for receiving, and / or means for selecting. Such means may include combining Figure 3 One or more components of UE 350 are described.

[0054] Figure 3 3 is a block diagram of a base station 310 communicating with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer packet data units (PDUs), error correction through automatic repeat request (ARQ), concatenation, segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0055] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1 including the physical (PHY) layer may include error detection on the transmission channel, forward error correction (FEC) encoding / decoding of the transmission channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols can then be split into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. Channel estimates may be derived from reference signals and / or channel condition feedback sent by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier for transmission using a corresponding spatial stream.

[0056] At the UE 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be combined into a single OFDM symbol stream by the RX processor 356. Then, the RX processor 356 uses a fast Fourier transform (FFT) to convert the OFDM symbol stream from the time domain to the frequency domain. The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation point sent by the base station 310. These soft decisions can be based on the channel estimate calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by the base station 310. The data and control signals are then provided to a controller / processor 359 that implements layer 3 and layer 2 functionality.

[0057] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0058] Similar to the functionality described in conjunction with DL transmissions performed by the base station 310, the controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0059] Channel estimates derived by the channel estimator 358 from a reference signal or feedback sent by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0060] UL transmissions are processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to the RX processor 370.

[0061] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0062] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to combine Figure 1 In addition, at least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to combine Figure 1 The streamlined SL-SS component 198 is used to perform various aspects.

[0063] Figure 4 is a diagram of a device-to-device (D2D) communication system 400 including vehicle-to-everything (V2X) communications in accordance with various aspects of the present disclosure. For example, the D2D communication system 400 can include V2X communications, (e.g., a first UE 450 communicating with a second UE 451). In some aspects, the first UE 450 and / or the second UE 451 can be configured to communicate in a licensed radio frequency spectrum and / or a shared radio frequency spectrum. The shared radio frequency spectrum can be unlicensed, and thus multiple different technologies can communicate using the shared radio frequency spectrum, including New Radio (NR), LTE, Advanced LTE, Licensed Assisted Access (LAA), Dedicated Short Range Communications (DSRC), MuLTEFire, 4G, etc. The foregoing list of technologies is considered illustrative and is not meant to be exhaustive.

[0064] The D2D communication system 400 can use NR radio access technology. Of course, other radio access technologies, such as LTE radio access technology, can also be used. In D2D communication (e.g., V2X communication or vehicle-to-vehicle (V2V) communication), UE450, 451 can be on the networks of different mobile network operators (MNOs). Each of the networks can operate in its own radio frequency spectrum. For example, the air interface (e.g., Uu interface) to the first UE 450 can be on one or more frequency bands different from the air interface of the second UE 451. The first UE 450 and the second UE 451 can communicate via a side link component carrier, for example, via a PC5 interface. In some examples, the MNO can schedule side link communications between or among UEs 450, 451 in a licensed radio frequency spectrum and / or a shared radio frequency spectrum (e.g., a 5 GHz radio spectrum band).

[0065] The shared radio frequency spectrum may be unlicensed, and thus different technologies may communicate using the shared radio frequency spectrum. In some aspects, D2D communications (eg, sidelink communications) between or among UEs 450, 451 are not scheduled by the MNO. The D2D communication system 400 may also include a third UE 452.

[0066] For example, the third UE 452 may operate on the first network 410 (e.g., of the first MNO) or another network. The third UE 452 may perform D2D communication with the first UE 450 and / or the second UE 451. The first base station 420 (e.g., gNB) may communicate with the third UE 452 via a downlink (DL) carrier 432 and / or an uplink (UL) carrier 442. DL communication may use various DL resources (e.g., DL subframes ( Figure 2A ) and / or DL ​​channel ( Figure 2B )). UL communication may use various UL resources (eg, UL subframes ( Figure 2C ) and UL channels ( Figure 2D )) to execute.

[0067] The first network 410 operates in a first spectrum and includes a first base station 420 (e.g., gNB) that communicates with at least a first UE 450, e.g., as Figures 1 to 3 The first base station 420 (eg, gNB) may communicate with the first UE 450 via the DL carrier 430 and / or the UL carrier 440. The DL communication may use various DL resources (eg, DL subframes ( Figure 2A ) and / or DL ​​channel ( Figure 2B )). UL communication may use various UL resources (eg, UL subframes ( Figure 2C ) and UL channels ( Figure 2D )) to execute.

[0068] In some aspects, the second UE 451 can be on a different network than the first UE 450. In some aspects, the second UE 451 can be on a second network 411 (e.g., of a second MNO). The second network 411 can operate in a second spectrum (e.g., a second spectrum different from the first spectrum) and can include a second base station 421 (e.g., a gNB) that communicates with the second UE 451, such as Figures 1 to 3 As described in.

[0069] The second base station 421 can communicate with the second UE 451 via the DL carrier 431 and the UL carrier 441. DL communication is performed via the DL carrier 431 using various DL resources (e.g., DL subframes ( Figure 2A ) and / or DL ​​channel ( Figure 2B UL communication is performed via the UL carrier 441 using various UL resources (e.g., UL subframes ( Figure 2C ) and / or UL channel ( Figure 2D )) to execute.

[0070] In a conventional system, the first base station 420 and / or the second base station 421 allocate resources for device-to-device (D2D) communication (e.g., V2X communication and / or V2V communication) to the UE. For example, these resources can be UL resource pools, both orthogonal (e.g., one or more FDM channels) and non-orthogonal (e.g., code division multiplexing (CDM) / resource extension multiple access (RSMA) in each channel). The first base station 420 and / or the second base station 421 can configure resources via PDCCH (e.g., a faster approach) or RRC (e.g., a slower approach).

[0071] In some systems, each UE 450, 451 autonomously selects resources for D2D communication. For example, each UE 450, 451 can sense and analyze channel occupancy during a sensing window. The UE 450, 451 can use the sensing information to select resources from the sensing window. As discussed, one UE 451 can assist another UE 450 in performing resource selection. The UE 451 providing assistance can be referred to as a receiver UE or partner UE, which can potentially inform the transmitter UE 450. The transmitter UE 450 can send information to the receiving UE 451 via side link communication.

[0072] D2D communication (e.g., V2X communication and / or V2V communication) may be implemented via one or more sidelink carriers 470, 480. The one or more sidelink carriers 470, 480 may include one or more channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH).

[0073] In some examples, the sidelink carriers 470, 480 can operate using a PC5 interface. The first UE 450 can transmit to one or more (e.g., multiple) devices, including transmitting to the second UE 451 via the first sidelink carrier 470. The second UE 451 can transmit to one or more (e.g., multiple) devices, including transmitting to the first UE 450 via the second sidelink carrier 480.

[0074] In some aspects, the UL carrier 440 and the first sidelink carrier 470 can be aggregated to increase bandwidth. In some aspects, the first sidelink carrier 470 and / or the second sidelink carrier 480 can share a first spectrum (with the first network 410) and / or share a second spectrum (with the second network 411). In some aspects, the sidelink carriers 470, 480 can operate in an unlicensed / shared radio frequency spectrum.

[0075] In some aspects, the sidelink communication on the sidelink carrier may occur between the first UE 450 and the second UE 451. In one aspect, the first UE 450 may perform sidelink communication with one or more (e.g., multiple) devices, including performing sidelink communication with the second UE 451 via the first sidelink carrier 470. For example, the first UE 450 may send a broadcast transmission to multiple devices (e.g., the second UE 451 and the third UE 452) via the first sidelink carrier 470. The second UE 451 (e.g., among other UEs) may receive this broadcast transmission. Additionally or alternatively, the first UE 450 may send a multicast transmission to multiple devices (e.g., the second UE 451 and the third UE 452) via the first sidelink carrier 470. The second UE 451 and / or the third UE 452 (e.g., among other UEs) may receive this multicast transmission. The multicast transmission may be connectionless or connection-oriented. The multicast transmission may also be referred to as a groupcast transmission.

[0076] In addition, the first UE 450 may send a unicast transmission to a device (such as, the second UE 451) via the first sidelink carrier 470. The second UE 451 (e.g., among other UEs) may receive this unicast transmission. Additionally or alternatively, the second UE 451 may perform sidelink communications with one or more (e.g., multiple) devices, including performing sidelink communications with the first UE 450 via the second sidelink carrier 480. For example, the second UE 451 may send a broadcast transmission to multiple devices via the second sidelink carrier 480. The first UE 450 (e.g., among other UEs) may receive this broadcast transmission.

[0077] In another example, the second UE 451 may send a multicast transmission to multiple devices (e.g., the first UE 450 and the third UE 452) via the second sidelink carrier 480. The first UE 450 and / or the third UE 452 (e.g., among the other UEs) may receive this multicast transmission. In addition, the second UE 451 may send a unicast transmission to a device (such as the first UE 450) via the second sidelink carrier 480. The first UE 450 (e.g., among the other UEs) may receive this unicast transmission. The third UE 452 may communicate in a similar manner.

[0078] In some aspects, for example, this sidelink communication on the sidelink carrier between the first UE 450 and the second UE 451 can occur without the MNO allocating resources for this communication (e.g., one or more portions of resource blocks (RBs), time slots, frequency bands, and / or channels associated with the sidelink carriers 470, 480) and / or without scheduling this communication. The sidelink communication may include traffic communications (e.g., data communications, control communications, paging communications, and / or system information communications). In addition, the sidelink communication may include sidelink feedback communications associated with the traffic communications (e.g., sending feedback information of previously received traffic communications). The sidelink communication may employ at least one sidelink communication structure having at least one feedback symbol. The feedback symbol of the sidelink communication structure may allocate any sidelink feedback information that may be communicated between devices (e.g., the first UE 450, the second UE 451, and / or the third UE 452) in a device-to-device (D2D) communication system 400. As discussed, the UE may be a vehicle (eg, UE 450, 451), a mobile device (eg, 452), or another type of device. In some cases, the UE may be a special UE, such as a roadside unit (RSU).

[0079] Figure 5 An example of a vehicle-to-everything (V2X) system 500 with a roadside unit (RSU) 510 is shown in accordance with aspects of the present disclosure. Figure 5As shown, the transmitter UE 504 transmits data to the RSU 510 and the receiving UE 502 via a sidelink transmission 512. Additionally or alternatively, the RSU 510 may transmit data to the transmitter UE 504 via the sidelink transmission 512. The RSU 510 may forward the data received from the transmitter UE 504 to the cellular network (e.g., gNB) 508 via an UL transmission 514. The gNB 508 may transmit the data received from the RSU 510 to other UEs 506 via a DL transmission 516. The RSU 510 may be integrated with traffic infrastructure (e.g., traffic lights, light poles, etc.). For example, Figure 5 As shown, the RSU 510 is a traffic signal located at a roadside 520. Additionally or alternatively, the RSU 510 may be a stand-alone unit.

[0080] In New Radio (NR) Vehicle-to-Everything (V2X) communications, the transmitting sidelink user equipment (UE) and the receiving sidelink UE should be synchronized to enable communication between each other, for example, for demodulation of received data. The UEs can be synchronized via a common base station or via a synchronized base station. When the UEs are in different non-synchronized cells or one or both of the UEs are out of network coverage, the UEs synchronize with each other via a sidelink synchronization signal (SL-SSS). The SL-SSB is sent within a sidelink synchronization signal block (S-SSB). The signals carried within the S-SSB include a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH). The S-PSS, S-SSS, and PSBCH together carry information such as the source ID of the transmitting UE, as well as synchronization information.

[0081] The bandwidth of the S-SSB is eleven resource blocks (RBs) within the bandwidth of the pre-configured sidelink bandwidth part (SL-BWP). The UE assumes that the parameter set of the SL-SS and PSBCH is the same as the parameter set of the SL-BWP received by the SL-SS / PSBCH block. The frequency position of the S-SSB is pre-configured. The UE assumes the frequency position corresponding to the subcarrier indexed 66 in the SL-SS / PSBCH block, which is provided by the parameter absoluteFrequencySSB-SL. Therefore, the UE does not perform hypothetical detection of the frequency position of the S-SSB for carriers in a given frequency band. In other words, the UE knows where to look for the S-SSB. The UE assumes that the subcarrier indexed 0 in the SL-SS / PSBCH block is aligned with the subcarrier indexed 0 in the SL-BWP. It should be noted that the potential, pre-configured frequency positions may be restricted.

[0082] The S-SSB period can be 160ms for all subcarrier spacings (SCS). The S-SSB resources in the time domain are pre-configured. The S-SSBs within the 160ms period are distributed at the same interval, and their pre-configured parameters are as follows: the offset from the start of the S-SSB period to the first S-SSB; and the interval between adjacent S-SSBs. For frequency range 1 (FR1-below 6GHz), the number of S-SSB transmissions within one S-SSB period is configurable: for 15kHz SCS, the number is {1}, for 30kHz SCS, the number is {1 or 2}, for 60kHz SCS, the number is {1, 2 or 4}, and for frequency range 2 (FR2-millimeter wave (mmW)): for 60kHz SCS, the number is {1, 2, 4, 8, 16 or 32}, and for 120kHz SCS, the number is {1, 2, 4, 8, 16, 32 or 64}.

[0083] Figure 6 is a diagram illustrating an orthogonal frequency division multiplexing (OFDM) symbol of a legacy sidelink synchronization signal block (S-SSB) according to aspects of the present disclosure. In particular, Figure 6 The New Radio (NR) S-SSB structure for a standard cyclic prefix is ​​shown in . The first symbol is used for PSBCH. The second and third symbols are used for S-PSS. The fourth and fifth symbols are used for S-SSS. Except for the last symbol, the remaining symbols are used for PSBCH. The last symbol is empty, forming a gap. No specific symbol(s) are reserved for automatic gain control (AGC) tuning. For the case of extended cyclic prefix, the structure is the same except that the number of PSBCH symbols after the S-SSS is only six.

[0084] The two symbols of the sidelink primary synchronization signal (S-PSS) can use the same sequence. The length 127 M sequence used for the S-PSS uses the same polynomial (e.g., x 7 +x 4 +1) and the same initial value, but a cyclic shift {22,65} that is different from the cyclic shift of the NR downlink primary synchronization signal (DL-PSS). In addition, the two symbols of the sidelink secondary synchronization signal (S-SSS) can use the same sequence. The Gold sequence of length 127 used for the S-SSS reuses the same polynomial, initial value and cyclic shift as the Gold sequence of the NR downlink secondary synchronization signal (DL-SSS). The UE assumes that the S-PSS symbols, S-SSS symbols, PSBCH demodulation reference signal (DM-RS) and PSBCH symbol data all have the same transmit power.

[0085] Different types of synchronization references are available. Example types of synchronization references include Global Navigation Satellite System (GNSS) based synchronization and gNB / eNB based synchronization. Each type of synchronization reference has a corresponding synchronization priority, which is pre-configured. For the sidelink (SL) synchronization procedure, the UE selects the synchronization reference with the highest priority as the reference for deriving its transmit timing. When two or more UE synchronization sources have the same priority, the UE selects the S-SSB with the highest reference signal received power (RSRP) as the synchronization source. The NR sidelink (SL) procedure for signaling, identifying the priority of one or more synchronization references and selecting a synchronization reference is similar to the Long Term Evolution (LTE) procedure.

[0086] The triggering of S-SSB transmission in NR V2X communication reuses the procedure in LTE V2X. That is, a UE in coverage can be directed by the gNB to become a synchronization reference and send a side link synchronization signal (SL-SS) to allow synchronization with other UEs. For example, the gNB can configure a threshold so that when the downlink RSRP drops below the configured threshold, the UE becomes a synchronization source and sends an SL-SS. A UE out of coverage can also become a synchronization reference when the UE has data to send. In this case, the UE sends an SL-SS, for example, when the RSRP from the current synchronization reference (e.g., another SL UE) drops below a pre-configured RSRP threshold. As an example, a UE out of coverage may become a synchronization reference once it does not receive a synchronization signal.

[0087] S-SSB transmissions may be resource inefficient and may also increase power consumption. For example, the described resource and power issues may occur if the sidelink (SL) UE sending the SL-SS is in deep coverage, if the SL UE sending the SL-SS is highly mobile, or if there are no nearby UEs to respond. The described resource and power issues may also occur during beam management when the UE sends SL-SS on FR2 (frequency range two, e.g., mmW), where multiple S-SSB blocks are specified within each 160ms for different beam directions. That is, there are more S-SSB opportunities because each S-SSB can be sent on a different beam.

[0088] According to aspects of the present disclosure, Lite S-SSB (or Lite SL-SS) achieves power savings and reduces system overhead of S-SSB transmission.

[0089] In some aspects, the transmitting (TX) UE sends a reduced SL-SS (or reduced S-SSB). The reduced SL-SS includes only S-PSS and / or S-SSS, without PSBCH. Figure 6As described, for standard CP (cyclic prefix) S-SSB, PSBCH appears on nine of the fourteen symbols of each S-SSB. Therefore, omitting PSBCH reduces the transmit power. In one configuration, the transmitting UE may be a power-constrained sidelink UE that may benefit from power savings.

[0090] Figure 7 is a block diagram of patterns of streamlined sidelink synchronization signal blocks (S-SSBs) in accordance with various aspects of the present disclosure. As seen in patterns 1-8, no PSBCH is transmitted. In pattern 1, there are two S-PSS symbols and two S-SSS symbols. In other aspects, as seen in patterns 2, 3, and 4, a sidelink UE transmitting SL-SS transmits S-PSS and S-SSS only once per S-SSB (not twice per S-SSB as in pattern 1). In still other aspects, as seen in patterns 5, 6, 7, and 8, a sidelink UE transmits only S-PSS or only S-SSS.

[0091] In another aspect of the present disclosure, the sidelink UE may use the SL-SS pattern based on instructions received from the gNB (e.g., for in-coverage scenarios) or pre-configured (e.g., for out-of-coverage scenarios). Alternatively, the sidelink UE may select the SL-SS pattern itself, for example, when out of network coverage. When the UE selects the pattern itself, the receiving UE should know which pattern is selected.

[0092] According to various aspects of the present disclosure, the SL-SS pattern may implicitly indicate (or be based on) information related to UE behavior. For example, the SL-SS pattern may implicitly indicate UE transmit power, UE mobility level, whether the UE is in coverage or out of coverage, etc. Figure 8 It is a diagram showing various aspects of the present disclosure. Figure 7 A subset of the styles shown in . For example, Figure 8 As seen in the figure, pattern 1 can indicate that the sidelink UE sending SL-SS is a high mobility UE. That is, the S-PSS and S-SSS symbols are repeated in pattern 1, helping the receiving UE to detect the signal while overcoming the Doppler effect. In this example, other patterns indicate that the sidelink transmitting UE is a low mobility and / or low power UE. In another example, patterns 2-4 can also indicate that the sidelink transmitting UE is within the network coverage (e.g., directly or indirectly) or outside the network coverage. Based on pattern detection, the receiving UE can learn more about the transmitting UE and can therefore decide whether to synchronize with the transmitting UE.

[0093] In some further aspects of the present disclosure, the SL-SS pattern explicitly indicates information about the transmitting UE. For example, the SL-SS may explicitly indicate the UE transmit power, mobility level, whether the UE is within coverage, etc. Currently, for NR V2X communications, the S-PSS and S-SSS together indicate 672 SL-SSIDs (side link service set identifiers). For example, SL-SSID{0,1,...,335} may indicate that the transmitting UE is within coverage or receives synchronization signals from a UE within coverage. SL-SSID{336,337,...671} may indicate that the transmitting UE does not have a connection to a UE within coverage. The PSBCH may include an indication of whether the UE sending the S-SSB itself is within the coverage of the cell.

[0094] According to various aspects of the present disclosure, the SL-SSID is divided as described above. Then, within each SL-SSID set, it is further divided into subsets indicating UE transmit power and / or mobility and / or coverage status (e.g., whether it is within coverage). For example, these sets can indicate UE transmit power, and these subsets can indicate coverage status. In these aspects, there are two SL-SSID sets, and several additional subsets are created.

[0095] In other aspects, a completely new partitioning of the SL-SSID occurs. For example, three SL-SSID sets may be created by partitioning the SSID into different sets and mapping the SL-SSID based on UE transmit power, mobility, coverage status, etc. An example of this is when the SL-SSID carries X+Y+Z bits, where X bits indicate UE transmit power, Y bits indicate U mobility, and Z bits indicate U coverage status.

[0096] Explicit and implicit signaling can be combined. For example, the selected pattern can implicitly indicate the transmit power, while the SL-SSID indicates whether the UE is in coverage.

[0097] From the perspective of the receiving side link UE, the streamlined SL-SS can have the same style as the legacy SL-SS (e.g., style 1). Alternatively, at the expense of more receiver complexity, the streamlined SL-SS can be sent using a different style (e.g., style 2-8), at a different frequency location, using a different (e.g., reserved) SL-SSID, and / or using a different timing offset. In some aspects of the present disclosure, the receiving side link UE searches for the streamlined SL-SS on a frequency (e.g., absoluteFrequencySSB-SL) indicated or pre-configured by the gNB. The frequency can be the same or different from the frequency of the legacy SL-SS. Of course, the transmitting side link UE transmits on this frequency. In these aspects, the indication (e.g., reserved SL-SSID and / or different frequency) indicates to the receiving UE whether a streamlined SL-SS or a legacy SL-SS is being sent to help the receiving UE decide whether to participate in the S-SSB.

[0098] In further aspects, the transmitting sidelink UE may send a compact SL-SS at a time offset (timeOffsetSSB-SL) indicated or preconfigured by the gNB. The time offset may be different or the same as the legacy SL-SS time offset. Different time offsets may reduce interference from neighboring UEs to the compact SL-SS sent by the power-limited UE. Preconfiguration may be for a resource pool, or for a sidelink carrier. In some aspects, the S-SSB patterns and / or the conditions for using them (e.g., power, mobility, etc.) may be preconfigured.

[0099] As indicated above, Figures 6 to 8 are provided as examples. Other examples can be found in the Figures 6 to 8 The examples described are different.

[0100] Fig. 9 9 is a flow chart of a method of wireless communication, illustrating an example process 900 performed, for example, by a transmitting sidelink UE according to various aspects of the present disclosure. Process 900 is an example of a simplified SL-SS (sidelink synchronization signal) transmission for an on-demand S-SSB (sidelink synchronization signal block).

[0101] like Fig. 9As shown, in some aspects, process 900 may include sending a side link synchronization signal (SL-SS) in a side link synchronization signal block (S-SSB) (box 902). The SL-SS has an SL-SS pattern with a reduced number of physical side link broadcast channel (PSBCH) symbols. For example, a UE (e.g., using antenna 352, RX / TX 354, TX processor 368, controller / processor 359 and / or memory 360) may send a SL-SS without PSBCH. The SL-SS pattern may be received from a network or pre-configured. The SL-SS pattern may explicitly or implicitly indicate various parameters of UE behavior. The side link UE may send the SL-SS at the same or different frequency as the legacy SL-SS. The side link UE may send the SL-SS at the same or different time as the legacy SL-SS. In some aspects, the SL-SS may be sent using a reserved SSID.

[0102] like Fig. 9 As shown in , in some aspects, process 900 may include receiving a transmission in accordance with SL-SS (block 904). For example, the UE (e.g., using antenna 352, RX / TX 354, RX processor 356, controller / processor 359, and / or memory 360) may receive a transmission.

[0103] Examples of implementations are described in the following numbered clauses:

[0104] 1. A method for wireless communication by a transmitting side link user equipment (UE), comprising:

[0105] transmitting a sidelink synchronization signal (SL-SS) within a sidelink synchronization signal block (S-SSB), the SL-SS having an SL-SS pattern with a reduced number of physical sidelink broadcast channel (PSBCH) symbols; and

[0106] Receive transmission according to SL-SS.

[0107] 2. A method according to clause 1, wherein the reduced number of symbols comprises zero symbols.

[0108] 3. A method according to clause 1 or 2, wherein the SL-SS pattern includes only a single sidelink primary synchronization signal (S-PSS) and a single sidelink secondary synchronization signal (S-SSS).

[0109] 4. A method according to any of the preceding clauses, wherein the SL-SS pattern comprises only a single sidelink primary synchronization signal (S-PSS).

[0110] 5. A method according to any of the preceding clauses, wherein the SL-SS pattern comprises only a plurality of sidelink primary synchronization signals (S-PSS).

[0111] 6. A method according to any of the preceding clauses, wherein the SL-SS pattern comprises only a single sidelink secondary synchronization signal (S-SSS).

[0112] 7. A method according to any of the preceding clauses, wherein the SL-SS pattern comprises only a plurality of sidelink secondary synchronization signals (S-SSSs).

[0113] 8. A method according to any of the preceding clauses, further comprising:

[0114] receiving a SL-SS pattern from a base station; and

[0115] When the sending side link UE is within the network coverage, SL-SS is sent using the SL-SS pattern.

[0116] 9. A method according to any one of the preceding clauses, wherein the SL-SS pattern is pre-configured, and the method further comprises: when the transmitting side link UE is out of network coverage, sending the SL-SS using the pre-configured SL-SS pattern.

[0117] 10. A method according to any of the preceding clauses, further comprising:

[0118] Select SL-SS style; and

[0119] Send SL-SS using SL-SS style.

[0120] 11. A method according to any one of the preceding clauses, wherein the SL-SS pattern implicitly indicates the transmit power of the transmitting side link UE, the mobility level of the transmitting side link UE and / or whether the transmitting side link UE is within the network coverage.

[0121] 12. A method according to any of the preceding clauses, wherein the SL-SS pattern explicitly indicates the UE behavior.

[0122] 13. A method according to any one of the preceding clauses, wherein the UE behavior includes the transmit power of the transmitting side link UE, the mobility level of the transmitting side link UE and / or whether the transmitting side link UE is within the network coverage.

[0123] 14. A method according to any of the preceding clauses, wherein the SL-SS pattern is explicitly indicated via a sidelink service set identifier (SL-SSID) of the transmitting sidelink UE.

[0124] 15. A method according to any one of the preceding clauses, wherein the SL-SSID indicates more than two characteristics of a transmitting side link UE based on two sets of SSIDs, the two sets including a first set indicating whether the UE is within coverage and a second set indicating whether the UE is not within coverage, the first set including at least two subsets, one of the subsets indicating the transmission power of the transmitting side link UE or the mobility level of the transmitting side link UE.

[0125] 16. A method according to any of the preceding clauses, wherein the SL-SSID indicates more than two characteristics of the transmitting side link UE based on more than two sets of SSIDs.

[0126] 17. The method of any of the preceding clauses, further comprising: transmitting the SL-SS on a first frequency that is different from a second frequency allocated to a legacy SL-SS.

[0127] 18. A method according to any of the preceding clauses, further comprising: receiving an indication of the first frequency from a base station.

[0128] 19. The method according to any of the preceding clauses, wherein the first frequency is pre-configured.

[0129] 20. The method of any of the preceding clauses, further comprising: sending the SL-SS on a frequency that is also allocated to a legacy SL-SS.

[0130] 21. The method of any of the preceding clauses, further comprising: transmitting the SL-SS at a first time offset from a second time during which the legacy SL-SS is transmitted.

[0131] 22. A method according to any of the preceding clauses, further comprising: receiving an indication of the offset from a base station.

[0132] 23. A method according to any of the preceding clauses, wherein the offset is preconfigured.

[0133] 24. The method according to any of the preceding clauses, further comprising: sending the SL-SS at a time that is also allocated to a legacy SL-SS.

[0134] 25. The method of any of the preceding clauses, further comprising: sending the SL-SS using a reserved service set identifier (SSID).

[0135] 26. An apparatus for wireless communication at a user equipment (UE), comprising:

[0136] processor;

[0137] a memory coupled to the processor; and

[0138] Instructions, which are stored in the memory and which, when executed by the processor, are operable to cause the apparatus to:

[0139] transmitting a sidelink synchronization signal (SL-SS) within a sidelink synchronization signal block (S-SSB), the SL-SS having an SL-SS pattern with a reduced number of physical sidelink broadcast channel (PSBCH) symbols; and

[0140] Receive transmission according to SL-SS.

[0141] 27. Apparatus according to clause 26, wherein the reduced number of symbols comprises zero symbols.

[0142] 28. An apparatus according to clause 26 or 27, wherein the SL-SS pattern explicitly indicates UE behavior, the UE behavior includes the transmit power of the transmitting side link UE, the mobility level of the transmitting side link UE and / or whether the transmitting side link UE is within the network coverage, the SL-SS pattern is explicitly indicated via the side link service set identifier (SL-SSID) of the transmitting side link UE, the SL-SSID indicates more than two characteristics of the transmitting side link UE based on at least two sets of SSIDs, the at least two sets including a first set indicating whether the UE is within the coverage and a second set indicating whether the UE is not within the coverage, the first set including at least two subsets, one of the subsets indicating the transmit power of the transmitting side link UE or the mobility level of the transmitting side link UE.

[0143] 29. An apparatus as recited in any of clauses 26 to 28, wherein the processor causes the apparatus to transmit the SL-SS on a first frequency that is different from a second frequency allocated to a legacy SL-SS.

[0144] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the various aspects.

[0145] As used, the term "component" is intended to be broadly interpreted as hardware, firmware, and / or a combination of hardware and software. As used, a processor is implemented in hardware, firmware, and / or a combination of hardware and software.

[0146] Some aspects are described in conjunction with a threshold value. As used, satisfying a threshold value may refer to a value that is greater than a threshold value, greater than or equal to a threshold value, less than a threshold value, less than or equal to a threshold value, equal to a threshold value, not equal to a threshold value, etc., depending on the context.

[0147] It will be clear that the described systems and / or methods can be implemented in various forms of hardware, firmware, and / or a combination of hardware and software. The actual dedicated control hardware or software code used to implement these systems and / or methods is not a limitation of the aspects. Therefore, the operation and behavior of the systems and / or methods are described without reference to specific software code - it should be understood that software and hardware can be designed to implement these systems and / or methods based at least in part on the present description.

[0148] Even if a specific combination of features is recorded in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of each aspect. In fact, many of these features can be combined in a manner that is not explicitly recorded in the claims and / or disclosed in the specification. Although each dependent claim listed below may be directly subordinate to only one claim, the disclosure of each aspect includes each dependent claim combined with each other claim in the claim set. The phrase "at least one" referring to a list of items refers to any combination of those items, including a single member. As an example, "at least one of a, b or c" is intended to cover a, b, c, ab, ac, bc and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc and ccc or any other ordering of a, b and c).

[0149] The elements, actions or instructions used should not be interpreted as key or necessary elements, actions or instructions, unless clearly described as such. In addition, as used, the articles "a" and "an" are intended to include one or more items, and can be used interchangeably with "one or more". In addition, as used, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, combinations of related items and unrelated items, etc.), and can be used interchangeably with "one or more". In the case of being intended to only one item, the phrase "only one" or similar language is used. In addition, as used, the terms "has", "have", "having" etc. are intended to be open terms. In addition, the phrase "based on" is intended to mean "based at least in part on", unless otherwise explicitly stated.

Claims

1. A method for wireless communication performed by a transmitting side link user equipment UE, comprising: transmitting a sidelink synchronization signal SL-SS within a sidelink synchronization signal block S-SSB, the S-SSB having an SL-SS pattern without physical sidelink broadcast channel PSBCH symbols and only with at least one sidelink primary synchronization signal S-PSS and / or at least one sidelink secondary synchronization signal S-SSS; and A transmission is received according to the SL-SS.

2. The method according to claim 1, wherein: The SL-SS pattern includes only a single sidelink primary synchronization signal S-PSS and a single sidelink secondary synchronization signal S-SSS.

3. The method according to claim 1, wherein: The SL-SS pattern includes only a single sidelink primary synchronization signal S-PSS.

4. The method according to claim 1, wherein: The SL-SS pattern includes only a plurality of sidelink primary synchronization signals S-PSS.

5. The method according to claim 1, wherein: The SL-SS pattern includes only a single sidelink secondary synchronization signal S-SSS.

6. The method according to claim 1, wherein: The SL-SS pattern includes only a plurality of sidelink secondary synchronization signals S-SSS.

7. The method according to claim 1, further comprising: Receiving the SL-SS pattern from a base station; as well as When the sending side link UE is within the network coverage, the SL-SS is sent using the SL-SS pattern.

8. The method according to claim 1, wherein: The SL-SS pattern is pre-configured, and the method further includes: when the transmitting side link UE is out of network coverage, sending the SL-SS using the pre-configured SL-SS pattern.

9. The method according to claim 1, further comprising: Select the SL-SS style; as well as The SL-SS is sent using the SL-SS pattern.

10. The method according to claim 1, wherein: The SL-SS pattern implicitly indicates the transmission power of the transmitting side link UE, the mobility level of the transmitting side link UE and / or whether the transmitting side link UE is within the network coverage.

11. The method according to claim 1, wherein: The SL-SS pattern explicitly indicates the UE behavior.

12. The method according to claim 11, wherein: The UE behavior includes the transmission power of the transmitting side link UE, the mobility level of the transmitting side link UE and / or whether the transmitting side link UE is within the network coverage.

13. The method according to claim 11, wherein: The SL-SS pattern is explicitly indicated via a sidelink service set identifier SL-SSID of the transmitting sidelink UE.

14. The method according to claim 13, wherein: The SL-SSID indicates more than two characteristics of the transmitting side link UE based on two sets of SSIDs, the two sets including a first set indicating whether the UE is within the coverage area and a second set indicating whether the UE is not within the coverage area, the first set including at least two subsets, one of the subsets indicating the transmitting power of the transmitting side link UE or the mobility level of the transmitting side link UE.

15. The method according to claim 13, wherein: The SL-SSID indicates more than two characteristics of the transmitting side link UE based on more than two sets of SSIDs.

16. The method according to claim 1, further comprising: The SL-SS is transmitted on a first frequency that is different from a second frequency allocated to a legacy SL-SS.

17. The method according to claim 16, further comprising: An indication of the first frequency is received from a base station.

18. The method according to claim 16, wherein: The first frequency is preconfigured.

19. The method of claim 1, further comprising: The SL-SS is transmitted on a frequency that is also allocated to the legacy SL-SS.

20. The method of claim 1, further comprising: The SL-SS is transmitted at a first time offset from a second time, and the legacy SL-SS is transmitted during the second time.

21. The method according to claim 20, further comprising: An indication of the offset is received from a base station.

22. The method according to claim 20, wherein: The offset is preconfigured.

23. The method of claim 1, further comprising: The SL-SS is transmitted at a time also allocated to the legacy SL-SS.

24. The method of claim 1, further comprising: The SL-SS is sent using a reserved service set identifier SSID.

25. An apparatus for wireless communication at a user equipment UE, comprising: processor; a memory coupled to the processor; as well as instructions stored in the memory and operable when executed by the processor to cause the apparatus to: transmitting a sidelink synchronization signal SL-SS within a sidelink synchronization signal block S-SSB, the S-SSB having an SL-SS pattern without physical sidelink broadcast channel PSBCH symbols and only with at least one sidelink primary synchronization signal S-PSS and / or at least one sidelink secondary synchronization signal S-SSS; and A transmission is received according to the SL-SS.

26. The device according to claim 25, wherein The SL-SS pattern explicitly indicates UE behavior, and the UE behavior includes the transmission power of the transmitting side link UE, the mobility level of the transmitting side link UE and / or whether the transmitting side link UE is within the network coverage. The SL-SS pattern is explicitly indicated via the side link service set identifier SL-SSID of the transmitting side link UE, and the SL-SSID indicates more than two characteristics of the transmitting side link UE based on at least two sets of SSIDs, and the at least two sets include a first set indicating whether the UE is within the coverage area and a second set indicating whether the UE is not within the coverage area. The first set includes at least two subsets, and one of the subsets indicates the transmission power of the transmitting side link UE or the mobility level of the transmitting side link UE.

27. The device according to claim 25, wherein: The processor causes the apparatus to transmit the SL-SS on a first frequency that is different from a second frequency allocated to a legacy SL-SS.

28. An apparatus for wireless communication performed by a transmitting side link user equipment UE, comprising: means for transmitting a sidelink synchronization signal SL-SS within a sidelink synchronization signal block S-SSB, said S-SSB having an SL-SS pattern without physical sidelink broadcast channel PSBCH symbols and only with at least one sidelink primary synchronization signal S-PSS and / or at least one sidelink secondary synchronization signal S-SSS; as well as Means for receiving a transmission in accordance with the SL-SS.

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