WO2025231811A1

WO2025231811A1 - Reference signal resource element allocation restriction for coherent joint tranmission under time domain duplexing

Info

Publication number: WO2025231811A1
Application number: PCT/CN2024/092267
Authority: WO
Inventors: Jing Dai; Mostafa KHOSHNEVISAN; Shaozhen GUO; Xiaoxia Zhang
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2024-05-10
Filing date: 2024-05-10
Publication date: 2025-11-13
Anticipated expiration: 2026-11-10

Abstract

The technology disclosed herein may allocate REs to each SRS to be transmitted by a UE to each of a plurality of CJT TRPs for time/phase alignment between TRPs and the UE, and to each of a plurality of CSI-RSs corresponding to the SRS and to be transmitted by TRPs to the UE, constrained as one or more of: for each CSI-RS associated with a same UE antenna port the SRS, allocating REs corresponding to a subset of RE frequencies allocated to the SRS, for the UE comprising multiple antenna ports, allocating REs to each CSI-RS associated with a TRP in separate symbols at frequencies common across antenna ports of a TRP, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP, and allocating REs to each CSI-RS at frequencies/cyclic shifts matching the SRS corresponding to the CSI-RS.

Description

[Rectified under Rule 91, 30.05.2024]REFERENCE SIGNAL RESOURCE ELEMENT ALLOCATION RESTRICTION FOR COHERENT JOINT TRANSMISSION UNDER TIME DOMAIN DUPLEXING

TECHNICAL FIELD

The present disclosure relates generally to communication systems, and more particularly in some examples to reference signal resource element (RE) allocation restriction for coherent joint transmission (CJT) under time domain duplexing (TDD) .

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. 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 technologies 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. These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is 5G New Radio (NR) . 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT) ) , and other requirements. 5G NR includes services associated with enhanced mobile broadband (eM10) , massive machine type communications (mMTC) , and ultra-reliable low latency communications (URLLC) . Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There exists a need for further improvements in 5G NR technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

In some aspects, the techniques described herein relate to a wireless communication methods in a wireless communication network implementing coherent joint transmission (CJT) using time division duplexing (TDD) , including: allocating, by a base station of the network, resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by a user equipment (UE) of the network to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of: for each CSI-RS associated with a same antenna port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE including a plurality of antenna ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the antenna ports associated with the given TRP; for the UE including a plurality of antenna ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and for the UE including a plurality of antenna ports, allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS; and transmitting, by the base station to the UE, the allocation of REs.

In some aspects, the techniques described herein relate to a wireless communication method in a wireless communication network implementing coherent joint transmission (CJT) using time division duplexing (TDD) , including: receiving, by a user equipment of the network, an allocation of resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by the UE to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of: for each CSI-RS associated with a same port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE including a plurality of ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP; for the UE including a plurality of ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP ; and for the UE including a plurality of ports , allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS; transmitting, by the UE to each TRP, one or more SRS per the received allocation; receiving, by the UE from a plurality of TRPs, CSI-RS per the allocation; and estimating, by the UE, inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs based on the transmitted SRS and receives CSI-RS.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network.

FIG. 2 is a diagram illustrating an example disaggregated base station architecture

FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D are diagrams illustrating examples of a first 5G/NR frame, DL channels within a 5G/NR subframe, a second 5G/NR frame, and UL channels within a 5G/NR subframe, respectively.

FIG. 4 is a diagram illustrating a base station and user equipment (UE) in an access network, in accordance with examples of the technology disclosed herein.

FIG. 5 is a process flow diagram for UE-assisted TRP synchronization for CJT operating in TDD, in accordance with examples of the technology disclosed herein.

FIG. 6 is a process flow diagram for UE-assisted TRP synchronization for CJT operating in TDD, in accordance with examples of the technology disclosed herein.

FIG. 7 is a flow diagram illustrating methods of wireless communication, in accordance with examples of the technology disclosed herein.

FIG. 8 illustrates a second type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 9 illustrates a first example of a third type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 10 illustrates a second example of the third type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 11 illustrates a third example of the third type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 12 illustrates a fourth example of the third type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 13 illustrates a fourth example of the third type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 14 illustrates a fourth example of the third type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 15 illustrates a fourth example of the third type of constraint, in accordance with examples of the technology disclosed herein.

FIG. 16 is a block diagram of a UE, in accordance with examples of the technology disclosed herein.

FIG. 17 is a block diagram of a base station, in accordance with examples of the technology disclosed herein.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Coherent Joint Transmission (CJT) is a method used in wireless communication, specifically in 5G NR, to improve signal quality and increase data rates. CJT involves multiple transmission reception points (TRPs) at one or more base stations transmitting the same data to a user equipment (UE) , such as a mobile phone, at roughly the same time and frequency. The signals from different TRPs are coordinated in such a way that the signals arrive coherently at the UE, meaning the signals add up constructively. This may increase the signal strength at the UE, improving the signal quality, increasing data rate, and enhancing the overall user experience. CJT may be particularly useful in scenarios where the UE is located at the cell edge and would typically experience poor signal quality due to interference from neighboring cells. By coordinating the transmissions from multiple TRPs, CJT can effectively overcome such interference and increase the signal-to-noise ratio at the UE.

With TRP-specific phase and timing misalignment under CJT operating in time division duplexing (TDD) , there can be a mismatch in the measured characteristics of the uplink channel (H^UL) and those of the downlink channel (H^DL) –thus undermining an assumption of downlink/uplink channel reciprocity. To maintain this assumption, it would be useful to use similar frequency and time resources in both uplink and downlink for channel measurement that are in some ways associated with the same channel coefficient h (f, t) .

The technology disclosed herein is applicable to mitigating one or more of the issues described above. In some examples of the technology disclosed herein, resources for sounding reference signals (SRSs) from the UE to each TRP and channel state information reference signals (CSI-RS) from each TRP to the UE are restricted one or more of several aspects, e.g., within and SRSs from between UE antenna ports, between SRS in uplink and CSI-RS in downlink, among CSI-RS in different sets (e.g., associated with a given antenna port) , and among different CSI-RS transmitted from the same TRP.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs) , central processing units (CPUs) , application processors, digital signal processors (DSPs) , reduced instruction set computing (RISC) processors, systems on a chip (SoC) , baseband processors, field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network 100. The wireless communications system (also referred to as a wireless wide area network (WWAN) ) includes base stations 102, UEs 104, an Evolved Packet Core (EPC) 160, and another core network 190 (e.g., a 5G Core (5GC) ) . The base stations 102 may include macrocells (high power cellular base station) and/or small cells (low power cellular base station) . The macro cells can include base stations. The small cells can include femtocells, picocells, and microcells. In an example, the base stations 102 may also include gNBs 180, as described further herein. Some nodes of the wireless communication system may have a modem 340 and UE communicating component for reporting PMI, relative phase between TRPs, frequency drift between TRPs, or relative delay between TRPs, in accordance with aspects described herein. In addition, some nodes may have a modem 440 and BS communicating component for precoding CJT transmissions based on reported PMI, relative phase between TRPs, frequency drift between TRPs, or relative delay between TRPs, in accordance with aspects described herein. Though a UE 104 is described as having the modem 340 and UE communicating component and a base station 102/gNB 180 is described as having the modem 440 and BS communicating component, this is one illustrative example, and substantially any node or type of node may include a modem 340 and UE communicating component and/or a modem 440 and BS communicating component for providing corresponding functionalities.

The base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN) ) may interface with the EPC 160 through first backhaul links 132 (e.g., S1 interface) . The base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN) ) may interface with core network 190 through second backhaul links186. In addition to other functions, the base stations 102 may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity) , inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS) , subscriber and equipment trace, RAN information management (RIM) , paging, positioning, and delivery of warning messages. The base stations 102 may communicate directly or indirectly (e.g., through the EPC 160 or core network 190) with each other over third backhaul links 134 (e.g., X2 interface) . The first, second and third backhaul links 132, 186 and 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102' may have a coverage area 110' that overlaps the coverage area 110 of one or more macro base stations 102. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs) , which may provide service to a restricted group known as a closed subscriber group (CSG) . The communication links 120 between the base stations 102 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a base station 102 and/or downlink (DL) (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity.

The communication links may be through one or more carriers. The base stations 102 /UEs 104 may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. 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) . The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell) .

Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the 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 communications systems, such as for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point 150 (AP 150) in communication with Wi-Fi stations (STAs) 152 via communication links 154 in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs 152 /AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available. The small cell 102' may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP. The small cell 102', employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

A base station 102, whether a small cell 102' or a large cell (e.g., macro base station) , may include and/or be referred to as an eNB, gNodeB (gNB) , or another type of base station. Some base stations, such as gNB 180 may operate in one or more frequency bands within the electromagnetic spectrum. The base station 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming.

The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In 5G NR two initial operating bands have been identified as frequency range designations FR1 (410 MHz –7.125 GHz) and FR2 (24.25 GHz –52.6 GHz) . The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as a “Sub-6 GHz” band in various documents and articles. A similar nomenclature issue sometimes occurs with regard to FR2, which is often referred to (interchangeably) as a “millimeter wave” (mmW) band in documents and articles, despite being different from the extremely high frequency (EHF) band (30 GHz –300 GHz) which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band.

With the above aspects in mind, unless specifically stated otherwise, it should be understood that the term “sub-6 GHz” or the like if used herein may broadly represent frequencies that may be less than 6 GHz, may be within FR1, or may include mid-band frequencies. Further, unless specifically stated otherwise, it should be understood that the term “millimeter wave” or the like if used herein may broadly represent frequencies that may include mid-band frequencies, may be within FR2, or may be within the EHF band. Communications using the mmW radio frequency band have extremely high path loss and a short range. The mmW base station 180 may utilize beamforming with the UE 104/184 to compensate for the path loss and short-range using beams 182.

The base station 180 may transmit a beamformed signal to the UE 104/184 in one or more transmit directions 182'. The UE 104/184 may receive the beamformed signal from the base station 180 in one or more receive directions 182”. The UE 104/184 may also transmit a beamformed signal to the base station 180 in one or more transmit directions. The base station 180 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 180 /UE 104/184 may perform beam training to determine the best receive and transmit directions for each of the base station 180 and UE 104/184. The transmit and receive directions for the base station 180 may or may not be the same. The transmit and receive directions for the UE 104/184 may or may not be the same.

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 be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation as well as other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a packet-switched (PS) Streaming Service, and/or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmission, 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 be used to distribute MBMS traffic to the base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

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. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is the control node that processes the signaling between the UEs 104 and the core network 190. Generally, the AMF 192 provides quality of service (QoS) flow and session management. All user Internet protocol (IP) packets are transferred through the UPF 195. The UPF 195 provides UE IP address allocation as well as other functions. The UPF 195 is connected to the IP Services 197. The IP Services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service, and/or other IP services.

The base station may also be referred to as a gNB, Node B, evolved Node B (eNB) , an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , a transmit reception point (TRP) , or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or 5GC 190 for a UE 104. Examples of UEs 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., 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 functioning device. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc. ) . IoT UEs may include machine type communication (MTC) /enhanced MTC (eMTC, also referred to as category (CAT) -M, Cat M1) UEs, NB-IoT (also referred to as CAT NB1) UEs, as well as other types of UEs. In the present disclosure, eMTC and NB-IoT may refer to future technologies that may evolve from or may be based on these technologies. For example, eMTC may include FeMTC (further eMTC) , eFeMTC (enhanced further eMTC) , mMTC (massive MTC) , etc., and NB-IoT may include eNB-IoT (enhanced NB-IoT) , FeNB-IoT (further enhanced NB-IoT) , etc. The 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 communications 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.

In some aspects, the techniques described herein relate to a wireless communication methods in a wireless communication network implementing CJT using time division duplexing TDD, including: allocating, by a base station 102/180 of the network 100, REs to i) each, of at least one, SRS to be transmitted by a UE (e.g., 104/184) of the network 100 to each of a plurality of CJT transmission TRPs of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of CSI-RSs, each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE (e.g., 104/184) , constrained as one or more of: for each CSI-RS associated with a same antenna port of the UE (e.g., 104/184) as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE (e.g., 104/184) including a plurality of antenna ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the antenna ports associated with the given TRP; for the UE (e.g., 104/184) including a plurality of antenna ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and for the UE (e.g., 104/184) including a plurality of antenna ports, allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS; and transmitting, by the base station to the UE (e.g., 104/184) , the allocation of REs.

In some aspects, the techniques described herein relate to a wireless communication method in a wireless communication network implementing CJT using TDD, including: receiving, by a user equipment of the network, an allocation of REs to i) each, of at least one, SRS to be transmitted by the UE (e.g., 104/184) to each of a plurality of CJT TRPs of the network for time and phase alignment between the TRPs and the UE (e.g., 104/184) , and ii) each of a plurality of CSI-RSs, each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE (e.g., 104/184) , constrained as one or more of: for each CSI-RS associated with a same port of the UE (e.g., 104/184) as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE (e.g., 104/184) including a plurality of ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP; for the UE (e.g., 104/184) including a plurality of ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP ; and for the UE (e.g., 104/184) including a plurality of ports , allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS; transmitting, by the UE (e.g., 104/184) to each TRP, one or more SRS per the received allocation; receiving, by the UE (e.g., 104/184) from a plurality of TRPs, CSI-RS per the allocation; and estimating, by the UE (e.g., 104/184) , inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs based on the transmitted SRS and receives CSI-RS...

Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

Deployment of communication systems, such as 5G new radio (NR) systems, may be arranged in multiple manners with various components or constituent parts. In a 5G NR system, or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element, or a network equipment, such as a base station (BS) , or one or more units (or one or more components) performing base station functionality, may be implemented in an aggregated or disaggregated architecture. For example, a BS (such as a Node B (NB) , evolved NB (eNB) , NR BS, 5G NB, access point (AP) , a transmit receive point (TRP) , or a cell, etc. ) may be implemented as an aggregated base station (also known as a standalone BS or a monolithic BS) or a disaggregated base station.

An aggregated base station may be configured to utilize a radio protocol stack that is physically or logically integrated within a single RAN node. A disaggregated base station may be configured to utilize a protocol stack that is physically or logically distributed among two or more units (such as one or more central or centralized units (CUs) , one or more distributed units (DUs) , or one or more radio units (RUs) ) . In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed throughout one or multiple other RAN nodes. The DUs may be implemented to communicate with one or more RUs. Each of the CU, DU and RU also can be implemented as virtual units, i.e., a virtual central unit (VCU) , a virtual distributed unit (VDU) , or a virtual radio unit (VRU) .

Base station-type operation or network design may consider aggregation characteristics of base station functionality. For example, disaggregated base stations may be utilized in an integrated access backhaul (IAB) network, an open radio access network (O-RAN (such as the network configuration sponsored by the O-RAN Alliance) ) , or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN) ) . Disaggregation may include distributing functionality across two or more units at various physical locations, as well as distributing functionality for at least one unit virtually, which can enable flexibility in network design. The various units of the disaggregated base station, or disaggregated RAN architecture, can be configured for wired or wireless communication with at least one other unit.

In some cases, BS communicating component can transmit a CSI-RS or other reference signal to a UE 104 via each of multiple TRPs, and UE communicating component can receive and measure the CSI-RS from each of the multiple TRPs to generate CSI, an associated PMI, etc. A UE communicating component can additionally compute or otherwise determine and report one or more of a relative phase, frequency drift, or relative delay between the RSs received from each of the multiple TRPs. BS communicating component can receive the report from the UE 104, and can use one or more of the relative phase, frequency drift, or relative delay between the TRPs to generate a precoder (e.g., a precoding matrix for respective TRPs) to use in precoding CJT transmissions for the UE 104.

FIG. 2 shows a diagram illustrating an example disaggregated base station 200 architecture. The disaggregated base station 200 architecture may include one or more central units (CUs) 210 that can communicate directly with a core network 220 via a backhaul link, or indirectly with the core network 220 through one or more disaggregated base station units (such as a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) 225 via an E2 link, or a Non-Real Time (Non-RT) RIC 215 associated with a Service Management and Orchestration (SMO) Framework 205, or both) . A CU 210 may communicate with one or more distributed units (DUs) 230 via respective mid-haul links, such as an F1 interface. The DUs 230 may communicate with one or more radio units (RUs) 240 via respective fronthaul links. The RUs 240 may communicate with respective UEs 202 via one or more radio frequency (RF) access links. In some implementations, the UE 202 may be simultaneously served by multiple RUs 240.

Each of the units, i.e., the CUs 210, the DUs 230, the RUs 240, as well as the Near-RT RICs 225, the Non-RT RICs 215 and the SMO Framework 205, may include one or more interfaces or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communication interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other units. Additionally, the units can include a wireless interface, which may include a receiver, a transmitter or transceiver (such as a radio frequency (RF) transceiver) , configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.

In some aspects, the CU 210 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC) , packet data convergence protocol (PDCP) , service data adaptation protocol (SDAP) , or the like. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 210. The CU 210 may be configured to handle user plane functionality (i.e., Central Unit –User Plane (CU-UP) ) , control plane functionality (i.e., Central Unit –Control Plane (CU-CP) ) , or a combination thereof. In some implementations, the CU 210 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bidirectionally with the CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 210 can be implemented to communicate with the DU 230, as necessary, for network control and signaling.

The DU 230 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 240. In some aspects, the DU 230 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the 3rd Generation Partnership Project (3GPP) . In some aspects, the DU 230 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 230, or with the control functions hosted by the CU 210.

Lower-layer functionality can be implemented by one or more RUs 240. In some deployments, an RU 240, controlled by a DU 230, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT) , inverse FFT (iFFT) , digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like) , or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU (s) 240 can be implemented to handle over the air (OTA) communication with one or more UEs 202. In some implementations, real-time and non-real-time aspects of control and user plane communication with the RU (s) 240 can be controlled by the corresponding DU 230. In some scenarios, this configuration can enable the DU (s) 230 and the CU 210 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO Framework 205 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 205 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (such as an O1 interface) . For virtualized network elements, the SMO Framework 205 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 290) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface) . Such virtualized network elements can include, but are not limited to, CUs 210, DUs 230, RUs 240 and Near-RT RICs 225. In some implementations, the SMO Framework 205 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-eNB) 211, via an O1 interface. Additionally, in some implementations, the SMO Framework 205 can communicate directly with one or more RUs 240 via an O1 interface. The SMO Framework 205 also may include a non-RT RIC 215 configured to support functionality of the SMO Framework 205.

The Non-RT RIC 215 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 225. The Non-RT RIC 215 may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC 225. The Near-RT RIC 225 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 210, one or more DUs 230, or both, as well as an O-eNB, with the Near-RT RIC 225.

In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 225, the Non-RT RIC 215 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 225 and may be received at the SMO Framework 205 or the Non-RT RIC 215 from non-network data sources or from network functions. In some examples, the non-RT RIC 215 or the Near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 215 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 205 (such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies) .

FIG. 3A is a diagram 300 illustrating an example of a first subframe within a 5G/NR frame structure. FIG. 3B is a diagram 330 illustrating an example of DL channels within a 5G/NR subframe. FIG. 3C is a diagram 350 illustrating an example of a second subframe within a 5G/NR frame structure. FIG. 3D is a diagram 380 illustrating an example of UL channels within a 5G/NR subframe. The 5G/NR frame structure may be frequency division duplexed (FDD) in which for a particular set of subcarriers (carrier system bandwidth) , subframes within the set of subcarriers are dedicated for either DL or UL, or may be time division duplexed (TDD) in which for a particular set of subcarriers (carrier system bandwidth) , subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided by FIGs. 3A, 3C, the 5G/NR frame structure is assumed to be TDD, with subframe 4 being configured with slot format 28 (with mostly DL) , where D is DL, U is UL, and X is flexible for use between DL/UL, and subframe 3 being configured with slot format 34 (with mostly UL) . While subframes 3, 4 are shown with slot formats 34, 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0, 1 are all DL, UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. UEs are configured with the slot format (dynamically through DL control information (DCI) , or semi-statically/statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI) . Note that the description infra applies also to a 5G/NR frame structure that is TDD.

Other wireless communication technologies may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms) . Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission) . The number of slots within a subframe is based on the slot configuration and the numerology. For slot configuration 0, different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2^μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2^μ*15 kHz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGs. 3A-3D provide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs) ) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs) . The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 3A, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include demodulation RS (DM-RS) (indicated as R_x for one particular configuration, where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS) , beam refinement RS (BRRS) , and phase tracking RS (PT-RS) . Some examples of the technology disclosed herein use the DM-RS of the physical downlink control channel (PDCCH) to aid in channel estimation (and eventual demodulation of the user data portions) of the physical downlink shared channel (PDSCH) .

FIG. 3B illustrates an example of various DL channels within a subframe of a frame. 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. A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE 104 to determine subframe/symbol timing and a physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI) . Based on the PCI, the UE can determine the locations of the aforementioned DM-RS. The physical broadcast channel (PBCH) , which carries a master information block (MIB) , may be logically grouped with the PSS and SSS to form a synchronization signal (SS) /PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN) . The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs) , and paging messages.

As illustrated in FIG. 3C, some of the REs carry DM-RS (indicated as R for one particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH) . The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. The UE may transmit sounding reference signals (SRS) . The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 3D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI) , such as scheduling requests, a channel quality indicator (CQI) , a precoding matrix indicator (PMI) , a rank indicator (RI) , and hybrid automatic repeat request (HARQ) acknowledgment (ACK) /negative 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.

FIG. 4 is a block diagram of a base station 410 in communication with a UE 450 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller/processor 475. The controller/processor 475 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 475 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs) , 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 (ciphering, deciphering, integrity protection, integrity verification) , and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs) , error correction through 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.

The transmit (TX) processor 416 and the receive (RX) processor 470 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 416 handles mapping to signal constellations 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 may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 474 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 450. Each spatial stream may then be provided to a different antenna 420 via a separate transmitter 418TX. Each transmitter 418TX may modulate a radio frequency (RF) carrier with a respective spatial stream for transmission.

At the UE 450, each receiver 454RX receives a signal through its respective antenna 452. Each receiver 454RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 456. The TX processor 468 and the RX processor 456 implement layer 1 functionality associated with various signal processing functions. The RX processor 456 may perform spatial processing on the information to recover any spatial streams destined for the UE 450. If multiple spatial streams are destined for the UE 450, they may be combined by the RX processor 456 into a single OFDM symbol stream. The RX processor 456 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT) . The frequency domain signal comprises 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 points transmitted by the base station 410. These soft decisions may be based on channel estimates computed by the channel estimator 458. The soft decisions are then decoded and de-interleaved to recover the data and control signals that were originally transmitted by the base station 410 on the physical channel. The data and control signals are then provided to the controller/processor 459, which implements layer 3 and layer 2 functionality.

The controller/processor 459 can be associated with a memory 460 that stores program codes and data. The memory 460 may be referred to as a computer-readable medium. In the UL, the controller/processor 459 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 459 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DL transmission by the base station 410, the controller/processor 459 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression /decompression, and security (ciphering, deciphering, integrity protection, integrity verification) ; RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC 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 TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator 458 from a reference signal or feedback transmitted by the base station 410 may be used by the TX processor 468 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 468 may be provided to different antenna 452 via separate transmitters 454TX. Each transmitter 454TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 410 in a manner similar to that described in connection with the receiver function at the UE 450. Each receiver 418RX receives a signal through its respective antenna 420. Each receiver 418RX recovers information modulated onto an RF carrier and provides the information to a RX processor 470.

The controller/processor 475 can be associated with a memory 476 that stores program codes and data. The memory 476 may be referred to as a computer-readable medium. In the UL, the controller/processor 475 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 450. IP packets from the controller/processor 475 may be provided to the EPC 160. The controller/processor 475 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations. As described elsewhere herein, the interface between a UE 450 and a base station 410 can be referred to as a “16” interface 490.

Referring to FIG. 5, and continuing to refer to prior figures for context, an example process 500 for UE-assisted TRP synchronization for CJT operating in TDD is illustrated, in accordance with examples of the technology disclosed herein. For simplicity, the example process shows two TRP transceivers from different TRPs (TRP1 520, TRP2 530) and single UE transceiver 510, while the principles apply to more than two TRPs and more than one UE transceiver/antenna port. The UE 510 transmits SRS 502 in uplink to both TRP 1 520 and TRP2 530. The signals received at each TRP 520, 530 can be described as:

where, for the receiving side (either TRP or UE) , ψ^Rx (k) =exp (j2πkτ^RxΔf+jφ^Rx) at subcarrier k; and for the transmitting side (either TRP or UE) , ψ^Tx (k) =exp (-j2πkτ^TxΔf-jφ^Tx) at subcarrier k. The SRS 502 should only be transmitted with a single transceiver 510, if phase coherence is not guaranteed b/w the UE’s transceivers.

Each TRP 520, 530 transmits a corresponding DL-RS (typically, single-port CSI-RS 524, 534) to the UE transceiver 510, where each CSI-RS 524, 534 is precoded based on at least the phase of the corresponding received SRS 502, e.g., phase conjugateandCSI-RS 524 534 precoding ensures that channel propagation delay and channel phase are canceled out, and thus no impact to y₁ 512, y₂ 513, described as:

UE 510 calculates 514This ensures that the phase of UE’s 510 Rx-Tx uncertainty is cancelled out, and the only remaining phase is the inter-TRP timing offset and inter-TRP phase offset: The inter-TRP timing offset and phase offset between the two TRPs 520, 530 (τ_TRP2to1, φ_TRP2to1) are estimated byacross subcarriers k=1, …, K over the entire bandwidth.

The estimated τ_TRP2to1, φ_TRP2to1 are reported 515 to one of the TRPs (e.g., TRP2 530) to synchronize 535 to the other TRP (e.g., TRP1 520) .

Referring to FIG. 6, and continuing to refer to prior figures for context, an example diagram 600 for UE-assisted TRP synchronization for CJT operating in TDD is illustrated, in accordance with examples of the technology disclosed herein. FIG. 6 shows CSI-RS sets/groups (601 corresponding to TRP1, 602 corresponding to TRP2, and 603 corresponding to TRP3) . Each CSI-RS set group contains separate CSI-RS corresponding to UE antenna port [1] and UE antenna port [2] , e.g., CSI-RS 601 [1] and CSI-RS 601 [2] are associated with TRP1 601. One CSI-RS per/TRP corresponds to an antenna pair across the UE 610 and a TRP such as TRP3 603, e.g., CSI-RS 601 [2] , CSI-RS 602 [2] , and CSI-RS 602 [2] correspond to antenna pair UE 610 [2] , TRP 610 [2] .

Referring to FIG. 7, and continuing to refer to prior figures for context, methods 700 for wireless communication are illustrated, in accordance with examples of the technology disclosed herein. Such methods find use in the context of a wireless communication network implementing coherent joint transmission (CJT) using time division duplexing (TDD) .

In such methods, a base station (e.g., base station 410) allocates resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by a user equipment (UE) (e.g., UE 450) of the network to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE 450, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE 450, constrained as one or more of four types of constraints –Block 710. In some examples, constraint to within a same resource block (RB) , rather than an RE, is sufficient to achieve the benefits of the technology disclosed herein. In some examples, the at least one SRS is an SRS or a set of SRS (s) for antenna port switch of the UE, and each of a plurality of CSI-RSs corresponds to an {SRS, port} pair.

In a first type of constraint, for each CSI-RS associated with a same antenna port of the UE 450 as the SRS, the base station 410 allocates REs corresponding to a subset of frequencies of REs allocated to the SRS. In this case, “subset” includes both all proper subsets and the equal (full) subset. For example, the base station 410 allocates REs for CSI-RS from antenna [1] of each of TRP1 601, TRP2 602, and TRP3 603 corresponding to SRS1 611 from antenna [1] of UE 450 across the full set of REs allocated to SRS1 611. Such an approach imposes restrictions within SRSs from between UE antenna ports, and between SRS in uplink and CSI-RS in downlink.

In a first example of the first type of constraint, for each CSI-RS associated with the same antenna port as the SRS, the base station 410 allocates REs of the same frequencies across the CSI-RS associated with the same port as the SRS. In a second example of the first type of constraint, for each CSI-RS associated with the same antenna port as the SRS, the base station 410 allocates REs to the SRS in frequency as comb-4/frequency-density-3, and allocating REs to the each of CSI-RS associated with the same antenna port as the SRS in frequency-density-3.

In a third example of the first type of constraint, for each particular CSI-RS associated with same antenna port as the SRS, the base station 410 allocates REs across the plurality of CSI-RS associated with the same antenna port as the SRS within a threshold duration. In some such examples, the threshold duration is a same slot or two consecutive slot. In a fourth example of the first type of constraint, for each CSI-RS associated with same antenna port as the SRS, the base station 410 allocate REs across the plurality of CSI-RS associated with the same antenna port as the SRS within a threshold time of a latest REs allocated to the SRS. In some such examples, the threshold duration is a same slot or two consecutive slot.

In a fifth example of the first type of constraint, for each particular CSI-RS associated with same antenna port as the SRS, the base station 410 allocates REs across the plurality of CSI-RS associated with the same antenna port as the SRS without a change in transmission direction across the time of the allocated CSI-RS REs. In a sixth example of the first type of constraint, for each particular CSI-RS associated with same antenna port as the SRS, the base station 410 allocates REs for each SRS and CSI-RS across ports of the UE with a common periodicity.

Referring to FIG. 8, and continuing to refer to prior figures for context, a second type of constraint 800 (aTDM constraint) is illustrated, in accordance with examples of the technology disclosed herein. In the second type of constraint, for a UE 610 comprising a plurality of antenna ports (e.g., SRS1 port 611 and SRS2 port 612) , the base station (410, 102, 180) allocates REs to each CSI-RS (each 601 [*] ) associated with a given TRP (e.g., TRP1 601, TRP2 602, TRP3 603) in separate symbols 810 at a set of frequencies common across the TRPs associated with a given antenna port.

In a first example of the second type of constraint, the base station allocates REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across TRPs associated with a given antenna port. In a second example of the second type of constraint, the base station allocatees REs across the plurality of CSI-RS associated with the given TRP within a threshold duration. In a third example of the second type of constraint, the base station allocates REs to each CSI-RS without interlace between CSI-RS corresponding to different antenna ports.

Referring to FIG. 9, and continuing to refer to prior figures for context, a first example of a third type of constraint 900 (an FDM constraint) is illustrated, in accordance with examples of the technology disclosed herein. In the first example of the third type of constraint, for the UE 450 comprising a plurality of antenna ports, the base station allocates REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP.

Referring to FIG. 10, and continuing to refer to prior figures for context, a second example of the third type of constraint is illustrated, in accordance with examples of the technology disclosed herein. In the second example of the third type of constraint, the base station allocates REs for each SRS using the same frequencies, but different (earlier) symbols as the REs of the CSI-RS corresponding to each SRS.

Referring to FIG. 11, and continuing to refer to prior figures for context, a third example of the third type of constraint is illustrated in accordance with examples of the technology disclosed herein. In the third example of the third type of constraint, the base station allocates REs such that each of the A SRSs has all the REs of the union of the A CSI-RSs.

Referring to FIG. 12, and continuing to refer to prior figures for context, a fourth example of the third type of constraint is illustrated in accordance with examples of the technology disclosed herein. In the third example of the third type of constraint, the base station allocates REs to each SRS corresponding to the CSI-RSs to a common symbol and different cyclic shifts.

Referring to FIG. 13, and continuing to refer to prior figures for context, in a fourth type of constraint is illustrated in accordance with examples of the technology disclosed herein. In such fourth type of constraint, for the UE comprising a plurality of antenna ports, the base station allocates REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS. In some such examples, the base station (410, 102, 180) allocates REs to each CSI-RS such that the A CSI-RSs are on same REs and with different cyclic shifts (CSs) –same cyclic shift as the SRS. In some such examples, CSI-RS uses sequences satisfying zero auto-correlation to its cyclic-shifted sequence (e.g. ZC-sequency, same as SRS) .

Referring to FIG. 14, and continuing to refer to prior figures for context, methods 1400 for wireless communication are illustrated, in accordance with examples of the technology disclosed herein. In such methods, Block 710 and Block 720 are performed as described earlier herein. In such methods, the base station 410 receives, from the UE 450, an estimate of inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs, the estimate determined by the UE based on SRS transmitted from the UE to each TRP and CSI-RS transmitted from each TRP to the UE in accordance with the transmitted allocation of REs –Block 1430.

In some examples, a non-transitory computer-readable medium storing computer-executable code that when executed by one or more processors of a receiving device causes the receiving device to execute one or both of method 700 and method 1400. In some examples, an apparatus such as base station 410 is operative, as described above, to perform one or both of method 700 and method 1400.

Referring to FIG. 15, and continuing to refer to prior figures for context, methods 1400 for wireless communication are illustrated, in accordance with examples of the technology disclosed herein.

In such examples, a user equipment (such as UE 450) can receive an allocation of resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by the UE to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained by one or more of the constraint types described above –Block 1510. In such examples, the UE transmits, to the base station, one or more SRS per the received allocation –Block 1520. The UE then receives, from a plurality of TRPs, CSI-RS per the allocation –Block 1530. After receiving the CSI-RS, the UE estimates inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs based on the transmitted SRS and receives CSI-RS.

Referring to FIG. 16, and continuing to refer to prior figures for context, another representation of the UE 450 for wireless communication of FIG. 4 is shown, in accordance with examples of the technology disclosed herein. UE 340 includes UE CJT RS Management Component 142, controller/processor 459, and memory 460, as described in conjunction with FIG. 4 above. The controller/processor 459 is coupled to the memory 460. The memory 460 including instructions executable by the controller/processor 459 to cause the UE 450 to perform the methods described herein.

UE CJT RS Management Component 142 includes receiving component 142a. In some examples, the receiving component 142a receives, an allocation of resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by the UE to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of: for each CSI-RS associated with a same port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE comprising a plurality of ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP; for the UE comprising a plurality of ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and for the UE comprising a plurality of ports , allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS.

Accordingly, receiving component 142a may provide means for receiving, an allocation of resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by the UE to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of: for each CSI-RS associated with a same port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE comprising a plurality of ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP; for the UE comprising a plurality of ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and for the UE comprising a plurality of ports , allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS.

UE CJT RS Management Component 142 includes transmitting component 142b. In some examples, the transmitting component 142b transmits, to the base station, one or more SRS per the received allocation. Accordingly, transmitting component 142b may provide means for transmitting, to the base station, one or more SRS per the received allocation.

UE CJT RS Management Component 142 includes second receiving component 142c. In some examples, the second receiving component 142c receives, from a plurality of TRPs, CSI-RS per the allocation. Accordingly, second receiving component 142c may provide means for receiving, by the UE from a plurality of TRPs, CSI-RS per the allocation.

UE CJT RS Management Component 142 includes estimating component 142d. In some examples, the estimating component 142d estimates inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs based on the transmitted SRS and receives CSI-RS. Accordingly, estimating component 142d may provide means for estimating, by the UE, inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs based on the transmitted SRS and receives CSI-RS.

Referring to FIG. 17, and continuing to refer to prior figures for context, another representation of the base station 410 for wireless communication of FIG. 4 is shown, in accordance with examples of the technology disclosed herein. Base station 410 (e.g., a gNB, a TRP) includes Base Station CJT RS Management Component 144, controller/processor 475, and memory 476, as described in conjunction with FIG. 4 above. The controller/processor 475 is coupled to the memory 476. The memory 476 including instructions executable by the controller/processor 475 to cause the base station 410 to perform the methods described herein.

Base Station CJT RS Management Component 144 includes allocating component 144a. In some examples, the allocating component 144a allocates resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by a UE 450 of the network to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of four types of constraints. The constraints include i) for each CSI-RS associated with a same antenna port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; ii) for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the antenna ports associated with the given TRP; iii) for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and iv) for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS.

Accordingly, allocating component 144a may provide means for allocating resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by a UE 450 of the network to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of four types of constraints. The constraints include i) for each CSI-RS associated with a same antenna port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; ii) for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the antenna ports associated with the given TRP; iii) for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and iv) for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS.

Base Station CJT RS Management Component 144 includes transmitting component 144b. In some examples, the transmitting component 144b transmitting, to the UE, the allocation of REs. Accordingly, transmitting component 144b may provide means for transmitting component 144b transmitting, to the UE, the allocation of REs.

In some examples, Base Station CJT RS Management Component 144 includes receiving component 144c. In some examples, the receiving component 144c receives, from the UE, an estimate of inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs, the estimate determined by the UE based on SRS transmitted from the UE to each TRP and CSI-RS transmitted from each TRP to the UE in accordance with the transmitted allocation of REs. Accordingly, receiving component 144c may provide means for receiving, from the UE, an estimate of inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs, the estimate determined by the UE based on SRS transmitted from the UE to each TRP and CSI-RS transmitted from each TRP to the UE in accordance with the transmitted allocation of REs.

The following examples are illustrative only and aspects thereof may be combined with aspects of other embodiments or teaching described herein, without limitation. The technology disclosed herein includes method, apparatus, and computer-readable media including instructions for wireless communication. Such technology finds use in the context of a UE capable of both half-duplex mode communication and full-duplex mode communication.

In Example 1, the techniques, devices, and non-transitory media containing instructions described herein relate to a wireless communication method in a user equipment (UE) , including wireless communication methods in a wireless communication network implementing coherent joint transmission (CJT) using time division duplexing (TDD) , including: allocating, by a base station of the network, resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by a user equipment (UE) of the network to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of: for each CSI-RS associated with a same antenna port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the antenna ports associated with the given TRP; for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS; and transmitting, by the base station to the UE, the allocation of REs.

Example 2 includes Example 1 further including receiving, by the base station from the UE, an estimate of inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs, the estimate determined by the UE based on SRS transmitted from the UE to each TRP and CSI-RS transmitted from each TRP to the UE in accordance with the transmitted allocation of REs.

Example 3 includes any one or more of the previous examples, further including, for each CSI-RS associated with the same antenna port as the SRS, allocating REs of the same frequencies across the CSI-RS associated with the same port as the SRS.

Example 4 includes any one or more of the previous examples, further including, for each CSI-RS associated with the same antenna port as the SRS, allocating REs to the SRS in frequency as comb-4/frequency-density-3, and allocating REs to the each of CSI-RS associated with the same antenna port as the SRS in frequency-density-3.

Example 5 includes any one or more of the previous examples, further including, for each particular CSI-RS associated with same antenna port as the SRS, allocating REs across the plurality of CSI-RS associated with the same antenna port as the SRS within a threshold duration.

Example 6 includes any one or more of the previous examples, wherein the threshold duration is a same slot or two consecutive slots.

Example 7 includes any one or more of the previous examples, further including, for each CSI-RS associated with same antenna port as the SRS, allocating REs across the plurality of CSI-RS associated with the same antenna port as the SRS within a threshold time of a latest REs allocated to the SRS.

Example 8 includes any one or more of the previous examples, wherein the threshold time is a same slot or two consecutive slots.

Example 9 includes any one or more of the previous examples, further including, for each particular CSI-RS associated with same antenna port as the SRS, allocating REs across the plurality of CSI-RS associated with the same antenna port as the SRS without a change in transmission direction across the time of the allocated CSI-RS REs.

Example 10 includes any one or more of the previous examples, further including, for each particular CSI-RS associated with same UE port as the SRS, allocating REs for each SRS and CSI-RS across ports of the UE with a common periodicity.

Example 11 includes any one or more of the previous examples, wherein allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across TRPs associated with a given antenna port.

Example 12 includes any one or more of the previous examples, wherein allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs across the plurality of CSI-RS associated with the given TRP within a threshold duration.

Example 13 includes any one or more of the previous examples, wherein allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS without interlace between CSI-RS corresponding to different antenna ports.

Example 14 includes any one or more of the previous examples, wherein, for the UE comprising a plurality of ports with CSI-RS multiplexed across frequencies of a single symbol for each TRP, allocating REs to each CSI-RS such that a union of frequencies of the REs allocated to CSI-RS across ports and TRPs is the same as the set of frequencies allocated to the set of corresponding SRSs across ports and TRPs.

Example 15 includes any one or more of the previous examples, further including, allocating each SRS corresponding to the CSI-RSs to a different symbol with a switch gap.

Example 16 includes any one or more of the previous examples, further including, allocating each SRS to the same REs as the REs of the CSI-RS corresponding to each SRS.

Example 17 includes any one or more of the previous examples, further including, allocating each SRS corresponding to the CSI-RSs to a common symbol and different cyclic shifts.

Example 18 includes any one or more of the previous examples, further including, where each constrain is to a REs within a resource block.

Example 19 is an apparatus for wireless communication, comprising: one or more memories storing computer-executable instructions; and one or more processors coupled with the one or more memories and configured to execute the computer-executable instructions, individually or in combination, to cause the apparatus to execute the method of any one or more of Example 1 –Example 18.

Example 20 is a non-transitory computer-readable medium storing computer-executable code that when executed by one or more processors of a receiving device causes the receiving device to execute the method of any one or more of Example 1 –Example 18.

Example 21 includes a wireless communication method in a wireless communication network implementing coherent joint transmission (CJT) using time division duplexing (TDD) , including: receiving, by a user equipment of the network, an allocation of resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by the UE to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of: for each CSI-RS associated with a same port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS; for the UE comprising a plurality of ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP; for the UE comprising a plurality of ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and for the UE comprising a plurality of ports , allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS;transmitting, by the UE to each TRP, one or more SRS per the received allocation; receiving, by the UE from a plurality of TRPs, CSI-RS per the allocation; and estimating, by the UE, inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs based on the transmitted SRS and receives CSI-RS.

Example 22 includes Example 21, wherein the allocation further comprises, for each CSI-RS associated with the same UE port as the SRS, an allocation of REs of the same frequencies across the CSI-RS associated with the same UE port as the SRS.

Example 23 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, for each CSI-RS associated with the same UE port as the SRS, an allocation of REs to the SRS in frequency as comb 4/frequency-density-3, and allocating REs to the each of CSI-RS associated with the same UE port as the SRS in frequency-density-3.

Example 24 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, for each particular CSI-RS associated with same UE port as the SRS, an allocation of REs across the plurality of CSI-RS associated with the same UE port as the SRS within a threshold duration.

Example 25 includes any one or more of Example 21 and later examples prior to this example, wherein the threshold duration is a same slot or two consecutive slots.

Example 26 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, for each CSI-RS associated with same UE port as the SRS, an allocation of REs across the plurality of CSI-RS associated with the same UE port as the SRS within a threshold time of a latest REs allocated to the SRS.

Example 27 includes any one or more of Example 21 and later examples prior to this example, wherein the threshold time is a same slot or two consecutive slots.

Example 28 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, for each particular CSI-RS associated with same UE port as the SRS, an allocation of REs across the plurality of CSI-RS associated with the same UE port as the SRS without a change in transmission direction across the time of the allocated CSI-RS REs.

Example 29 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, for each particular CSI-RS associated with same UE port as the SRS, an allocation of REs for each SRS and CSI-RS across ports of the UE with a common periodicity.

Example 30 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises an allocation of REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across TRPs associated with a given port.

Example 31 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises an allocation of REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs across the plurality of CSI-RS associated with the given TRP within a threshold duration.

Example 32 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises an allocation of REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS without interlace between CSI-RS corresponding to different ports.

Example 33 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, for the UE comprising a plurality of ports with CSI-RS multiplexed across frequencies of a single symbol for each TRP, an allocation of REs to each CSI-RS such that a union of frequencies of the REs allocated to CSI-RS across ports and TRPs is the same as the set of frequencies allocated to the set of corresponding SRSs across ports and TRPs.

Example 34 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, an allocation of REs to each SRS corresponding to the CSI-RSs to a different symbol.

Example 35 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, an allocation of REs to each SRS to the same REs as the REs of the CSI-RS corresponding to each SRS.

Example 36 includes any one or more of Example 21 and later examples prior to this example, wherein the allocation further comprises, an allocation of REs to each SRS corresponding to the CSI-RSs to a common symbol and different cyclic shifts.

Example 37 includes a user equipment (UE) for wireless communication, including: one or more memories storing computer-executable instructions; and one or more processors coupled with the one or more memories and configured to execute the computer-executable instructions, individually or in combination, to cause the UE to execute the method of any one or more of claims 21 -36.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”

Claims

A wireless communication method in a wireless communication network implementing coherent joint transmission (CJT) using time division duplexing (TDD) , comprising:

allocating, by a base station of the network, resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by a user equipment (UE) of the network to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of:

for each CSI-RS associated with a same antenna port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS;

for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the antenna ports associated with the given TRP;

for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP; and

for the UE comprising a plurality of antenna ports, allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS; and

transmitting, by the base station to the UE, the allocation of REs.
The method of claim 1, further comprising:

receiving, by the base station from the UE, an estimate of inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs, the estimate determined by the UE based on SRS transmitted from the UE to each TRP and CSI-RS transmitted from each TRP to the UE in accordance with the transmitted allocation of REs.
The method of claim 1, further comprising, for each CSI-RS associated with the same antenna port as the SRS, allocating REs of the same frequencies across the CSI-RS associated with the same port as the SRS.
The method of claim 1, further comprising, for each CSI-RS associated with the same antenna port as the SRS, allocating REs to the SRS in frequency as comb-4/frequency-density-3, and allocating REs to the each of CSI-RS associated with the same antenna port as the SRS in frequency-density-3.
The method of claim 1, further comprising, for each particular CSI-RS associated with same antenna port as the SRS, allocating REs across the plurality of CSI-RS associated with the same antenna port as the SRS within a threshold duration.
The method of claim 5, wherein the threshold duration is a same slot or two consecutive slots.
The method of claim 1, further comprising, for each CSI-RS associated with same antenna port as the SRS, allocating REs across the plurality of CSI-RS associated with the same antenna port as the SRS within a threshold time of a latest REs allocated to the SRS.
The method of claim 7, wherein the threshold time is a same slot or two consecutive slots.
The method of claim 1, further comprising, for each particular CSI-RS associated with same antenna port as the SRS, allocating REs across the plurality of CSI-RS associated with the same antenna port as the SRS without a change in transmission direction across the time of the allocated CSI-RS REs.
The method of claim 1, further comprising, for each particular CSI-RS associated with same UE port as the SRS, allocating REs for each SRS and CSI-RS across ports of the UE with a common periodicity.
The method of claim 1, wherein allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across TRPs associated with a given antenna port.
The method of claim 1, wherein allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs across the plurality of CSI-RS associated with the given TRP within a threshold duration.
The method of claim 1, wherein allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS without interlace between CSI-RS corresponding to different antenna ports.
The method of claim 1, wherein, for the UE comprising a plurality of ports with CSI-RS multiplexed across frequencies of a single symbol for each TRP, allocating REs to each CSI-RS such that a union of frequencies of the REs allocated to CSI-RS across ports and TRPs is the same as the set of frequencies allocated to the set of corresponding SRSs across ports and TRPs.
The method of claim 14, further comprising, allocating each SRS corresponding to the CSI-RSs to a different symbol with a switch gap.
The method of claim 14, further comprising, allocating each SRS to the same REs as the REs of the CSI-RS corresponding to each SRS.
The method of claim 14, further comprising, allocating each SRS corresponding to the CSI-RSs to a common symbol and different cyclic shifts.
The method of any one or more of claims 1-17, wherein the SRS is an SRS or a set of SRSs for antenna port switch of the UE, and each of a plurality of CSI-RSs corresponds to an {SRS, port} pair.
An apparatus for wireless communication, comprising:

one or more memories storing computer-executable instructions; and

one or more processors coupled with the one or more memories and configured to execute the computer-executable instructions, individually or in combination, to cause the apparatus to execute the method of any one or more of claims 1-17.
A non-transitory computer-readable medium storing computer-executable code that when executed by one or more processors of a receiving device causes the receiving device to execute the method of any one or more of claims 1-17.
A wireless communication method in a wireless communication network implementing coherent joint transmission (CJT) using time division duplexing (TDD) , comprising:

receiving, by a user equipment of the network, an allocation of resource elements (REs) to i) each, of at least one, sounding reference signal (SRS) to be transmitted by the UE to each of a plurality of CJT transmission reception points (TRPs) of the network for time and phase alignment between the TRPs and the UE, and ii) each of a plurality of Channel State Information Reference Signals (CSI-RSs) , each such CSI-RS corresponding to the SRS and to be transmitted by one of the TRPs to the UE, constrained as one or more of:

for each CSI-RS associated with a same port of the UE as the SRS, allocating REs corresponding to a subset of frequencies of REs allocated to the SRS ;

for the UE comprising a plurality of ports, allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP ;

for the UE comprising a plurality of ports, allocating REs to each CSI-RS multiplexed across frequencies of a single symbol for each TRP ; and

for the UE comprising a plurality of ports , allocating REs to each CSI-RS at a set of frequencies and cyclic shifts matching the SRS corresponding to the CSI-RS;

transmitting, by the UE to each TRP, one or more SRS per the received allocation;

receiving, by the UE from a plurality of TRPs, CSI-RS per the allocation; and

estimating, by the UE, inter-TRP time offset and inter-TRP phase offset between the plurality of TRPs based on the transmitted SRS and receives CSI-RS.
The method of claim 21, wherein the allocation further comprises, for each CSI-RS associated with the same UE port as the SRS, an allocation of REs of the same frequencies across the CSI-RS associated with the same UE port as the SRS.
The method of claim 21, wherein the allocation further comprises, for each CSI-RS associated with the same UE port as the SRS, an allocation of REs to the SRS in frequency as comb 4/frequency-density-3, and allocating REs to the each of CSI-RS associated with the same UE port as the SRS in frequency-density-3.
The method of claim 21, wherein the allocation further comprises, for each particular CSI-RS associated with same UE port as the SRS, an allocation of REs across the plurality of CSI-RS associated with the same UE port as the SRS within a threshold duration.
The method of claim 24, wherein the threshold duration is a same slot or two consecutive slots.
The method of claim 21, wherein the allocation further comprises, for each CSI-RS associated with same UE port as the SRS, an allocation of REs across the plurality of CSI-RS associated with the same UE port as the SRS within a threshold time of a latest REs allocated to the SRS.
The method of claim 26, wherein the threshold time is a same slot or two consecutive slots.
The method of claim 21, wherein the allocation further comprises, for each particular CSI-RS associated with same UE port as the SRS, an allocation of REs across the plurality of CSI-RS associated with the same UE port as the SRS without a change in transmission direction across the time of the allocated CSI-RS REs.
The method of claim 21, wherein the allocation further comprises, for each particular CSI-RS associated with same UE port as the SRS, an allocation of REs for each SRS and CSI-RS across ports of the UE with a common periodicity.
The method of claim 21, wherein the allocation further comprises an allocation of REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across TRPs associated with a given port.
The method of claim 21, wherein the allocation further comprises an allocation of REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs across the plurality of CSI-RS associated with the given TRP within a threshold duration.
The method of claim 21, wherein the allocation further comprises an allocation of REs to each CSI-RS associated with a given TRP in separate symbols at a set of frequencies common across the ports associated with the given TRP, further comprises allocating REs to each CSI-RS without interlace between CSI-RS corresponding to different ports.
The method of claim 21, wherein the allocation further comprises, for the UE comprising a plurality of ports with CSI-RS multiplexed across frequencies of a single symbol for each TRP, an allocation of REs to each CSI-RS such that a union of frequencies of the REs allocated to CSI-RS across ports and TRPs is the same as the set of frequencies allocated to the set of corresponding SRSs across ports and TRPs.
The method of claim 33, wherein the allocation further comprises, an allocation of REs to each SRS corresponding to the CSI-RSs to a different symbol.
The method of claim 33, wherein the allocation further comprises, an allocation of REs to each SRS to the same REs as the REs of the CSI-RS corresponding to each SRS.
The method of claim 33, wherein the allocation further comprises, an allocation of REs to each SRS corresponding to the CSI-RSs to a common symbol and different cyclic shifts.
[Rectified under Rule 91, 04.06.2024]
The method of any one or more of claims 21-36, wherein the SRS is an SRS or a set of SRSs for antenna port switch of the UE, and each of a plurality of CSI-RSs corresponds to an {SRS, port} pair.
A user equipment (UE) for wireless communication, comprising:

one or more memories storing computer-executable instructions; and

one or more processors coupled with the one or more memories and configured to execute the computer-executable instructions, individually or in combination, to cause the UE to execute the method of any one or more of claims 21 -36.