Flexible CSI and SRS association for uplink MIMO

Abstract

Various aspects of the present disclosure generally relate to wireless communications. In certain aspects, a user equipment may determine a set of sounding reference signals (SRS) based at least in part on a mapping configuration associated with mapping the set of SRS to a set of channel state information reference signals (CSI-RS) received by the UE, and the set of CSI-RS is received based at least in part on a set of receive settings, each receive setting associated with a corresponding CSI-RS in the set of CSI-RS; determine a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a corresponding SRS in the set of SRS; and transmit the set of SRS based at least in part on the set of transmit settings. Many other aspects are provided.

Description

Technical Field

[0001] Aspects of the present disclosure relate generally to wireless communications and techniques and apparatus for flexible channel state information reference signal (CSI-RS) and sounding reference signal (SRS) association for uplink multiple-input multiple-output (MIMO). Background Art

[0002] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies that can support communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and long term evolution (LTE). LTE / LTE-Advanced is a collection of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP).

[0003] A wireless communication network may include multiple base stations (BS) that can support communications for multiple user equipment (UE). User equipment (UE) can communicate with a base station (BS) via a downlink and an uplink. A downlink (or forward link) refers to a communication link from a BS to a UE, and an uplink (or reverse link) refers to a communication link from a UE to a BS. As will be described in more detail herein, a BS may be referred to as a Node B, gNB, access point (AP), radio head, transmit receive point (TRP), new radio (NR) BS, 5G Node B, and the like.

[0004] The above-mentioned multiple access technologies have been used in various telecommunication standards to provide a common protocol that enables different user equipment to communicate at a city, country, region, or even global level. New Radio (NR) (also referred to as 5G) is a collection of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and using orthogonal frequency division multiplexing (OFDM) (CP-OFDM) with a cyclic prefix (CP) on the downlink (DL), using CP-OFDM and / or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), and supporting beamforming, multiple input multiple output (MIMO) antenna technology, and carrier aggregation. Other open standards are better integrated to better support mobile broadband Internet access. However, as the demand for mobile broadband access continues to increase, there is a need for further improvements to LTE and NR technologies. Preferably, these improvements should be applicable to other multiple access technologies and telecommunication standards that adopt these technologies. Summary of the invention

[0005] In certain aspects, a method of wireless communication performed by a UE may include: determining a set of SRSs based at least in part on a mapping configuration, the mapping configuration being associated with mapping the set of SRSs to a set of CSI-RSs received by the UE, and the set of CSI-RSs being received based at least in part on a set of receive settings, each receive setting being associated with a corresponding CSI-RS in the set of CSI-RSs; determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a corresponding SRS in the set of SRSs; and transmitting the set of SRSs based at least in part on the set of transmit settings.

[0006] In certain aspects, a UE for wireless communication may include a memory and one or more processors operably coupled to the memory. The memory and the one or more processors may be configured to: determine a set of SRSs based at least in part on a mapping configuration associated with mapping the set of SRSs to a set of CSI-RSs received by the UE, and the set of CSI-RSs is received based at least in part on a set of receive settings, each receive setting associated with a corresponding CSI-RS in the set of CSI-RSs; determine a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a corresponding SRS in the set of SRSs; and transmit the set of SRSs based at least in part on the set of transmit settings.

[0007] In certain aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. When executed by one or more processors of a UE, the one or more instructions may cause the one or more processors to: determine a set of SRSs based at least in part on a mapping configuration associated with mapping the set of SRSs to a set of CSI-RSs received by the UE, and the set of CSI-RSs is received based at least in part on a set of receive settings, each receive setting associated with a corresponding CSI-RS in the set of CSI-RSs; determine a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a corresponding SRS in the set of SRSs; and transmit the set of SRSs based at least in part on the set of transmit settings.

[0008] In certain aspects, an apparatus for wireless communication may include: components for determining a set of SRSs based at least in part on a mapping configuration, the mapping configuration being associated with mapping the set of SRSs to a set of CSI-RSs received by the apparatus, and the set of CSI-RSs being received based at least in part on a set of receive settings, each receive setting being associated with a corresponding CSI-RS in the set of CSI-RSs; components for determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a corresponding SRS in the set of SRSs; and components for transmitting the set of SRSs based at least in part on the set of transmit settings.

[0009] As fully described herein with reference to and as illustrated in the accompanying drawings and description, aspects generally include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and / or processing systems.

[0010] The foregoing has been fairly extensively summarized according to the features and technical advantages of the examples of the present disclosure, so that the following detailed description can be better understood. Additional features and advantages will be described below. The disclosed concepts and specific examples can be easily used as the basis for modifying or designing other structures for achieving the same purpose of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. When considered in conjunction with the attached drawings, the characteristics of the concepts disclosed herein (its organization and method of operation) together with the associated advantages will be better understood according to the following description. Each of the accompanying drawings is provided for the purpose of illustration and description, rather than as a definition of the limitations of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order that the above-mentioned features of the present disclosure may be understood in detail, a more specific description briefly summarized above may be made with reference to various aspects, some of which are shown in the attached drawings. However, it should be noted that the attached drawings only show certain typical aspects of the present disclosure and therefore should not be considered to limit the scope of the present disclosure, as the present specification may admit other equivalent aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0012] Figure 1 is a block diagram conceptually illustrating an example of a wireless communication network in accordance with aspects of the present disclosure.

[0013] Figure 2 is a block diagram conceptually illustrating an example of a base station communicating with a UE in a wireless communication network according to aspects of the present disclosure.

[0014] Figures 3A-3C is a diagram illustrating examples associated with flexible CSI-RS and SRS association for uplink MIMO according to aspects of the present disclosure.

[0015] Figure 4 is a diagram illustrating an example process performed, for example, by a user device, according to aspects of the present disclosure. DETAILED DESCRIPTION

[0016] The various aspects of the present disclosure will be described more fully below with reference to the accompanying drawings. However, the present disclosure can be embodied in many different forms and should not be interpreted as being limited to any specific structure or function presented throughout the present disclosure. Specifically, these aspects are provided to make the present disclosure detailed and complete, and to fully convey the scope of the present disclosure to those skilled in the art. Based on the teachings of this article, it should be understood by those skilled in the art that the scope of the present disclosure is intended to cover any aspect of the disclosure disclosed herein, regardless of whether these aspects are implemented independently of any other aspect of the present disclosure or implemented in combination with any other aspect of the present disclosure. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover devices or methods practiced using other structures, functionality, or structures and functionality as additions to the various aspects of the disclosure set forth herein or in addition to the various aspects of the disclosure set forth herein. It should be understood that any aspect of the present disclosure may be embodied by one or more elements in the claims.

[0017] Several aspects of telecommunication systems will now be presented with reference to various devices and techniques. These devices and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0018] It should be noted that although terms commonly associated with 3G and / or 4G wireless technologies may be used herein to describe various aspects, aspects of the present disclosure may be applied to communication systems based on other generations, such as 5G and later generations, including NR technology.

[0019] Figure 1 1 is a diagram illustrating a wireless network 100 in which various aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include a plurality of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with a user equipment (UE) and may also be referred to as a base station, NR BS, Node B, gNB, 5G Node B (NB), access point, transmit receive point (TRP), etc. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to a coverage area of ​​a BS and / or a BS subsystem serving this coverage area, depending on the context in which the term "cell" is used.

[0020] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access to UEs with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access to UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow limited access to UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In Figure 1In the example shown, BS 110a may be a macro BS for macro cell 102a, BS 110b may be a pico BS for pico cell 102b, and BS 110c may be a femto BS for femto cell 102c. A BS may support one or more (e.g., three) cells. The terms "eNB", "base station", "NR BS", "gNB", "TRP", "AP", "Node B", "5G NB", and "cell" may be used interchangeably herein.

[0021] In some aspects, the cell may not necessarily be fixed, and the geographical area of ​​the cell may move according to the location of the mobile BS. In some aspects, the BSs may be interconnected with each other and / or with one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as direct physical connections, virtual networks, etc. using any suitable transport network.

[0022] The wireless network 100 may also include a relay station. A relay station is an entity that can receive transmissions of data from an upstream station (e.g., a BS or a UE) and send transmissions of data to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that can relay transmissions for other UEs. Figure 1 In the example shown, a relay station 110d may communicate with the macro BS 110a and the UE 120d to facilitate communication between the BS 110a and the UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, or the like.

[0023] The wireless network 100 may be a heterogeneous network including different types of BSs (e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc.). These different types of BSs may have different transmit power levels, different coverage areas, and different effects on interference in the wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 5 to 40 watts), while a pico BS, a femto BS, and a relay BS may have a lower transmit power level (e.g., 0.1 to 2 watts).

[0024] The network controller 130 may be coupled to a set of BSs and may provide coordination and control for these BSs. The network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with each other (eg, directly or indirectly) via a wireless or wired backhaul.

[0025] UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout the wireless network 100, and each UE may be fixed or mobile. UEs may also be referred to as access terminals, terminals, mobile stations, subscriber units, stations, etc. UEs may be cellular phones (e.g., smart phones), personal digital assistants (PDAs), wireless modems, wireless communication devices, handheld devices, laptop computers, cordless phones, wireless local loop (WLL) stations, tablets, cameras, gaming devices, netbooks, smartbooks, ultrabooks, medical devices or equipment, biometric sensors / devices, wearable devices (smart watches, smart clothing, smart glasses, smart wristbands, smart jewelry (e.g., smart rings, smart bracelets)), entertainment devices (e.g., music or video devices, or satellite radios), vehicle-mounted components or sensors, smart meters / sensors, industrial manufacturing equipment, global positioning system devices, or any other suitable device configured to communicate via wireless or wired media.

[0026] Some UEs may be considered as machine type communication (MTC) UEs, or evolved or enhanced machine type communication (eMTC) UEs. MTC UEs and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc. that can communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node may provide connectivity, for example, for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered as Internet of Things (IoT) devices, and / or may be implemented as NB-IoT (narrowband Internet of Things) devices. Some UEs may be considered as customer premises equipment (CPE). UE 120 may be included in a housing that houses components of UE 120 (such as a processor component, a memory component, etc.).

[0027] Generally, any number of wireless networks can be deployed in a given geographic area. Each wireless network can support a specific radio access technology (RAT) and can operate on one or more frequencies. RAT can also be referred to as radio technology, air interface, etc. Frequency can also be referred to as carrier, frequency channel, etc. Each frequency can support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks can be deployed.

[0028] In certain aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly (e.g., without using base station 110 as an intermediary for communicating with each other) using one or more side link channels. For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, etc.), mesh networks, etc. In this case, UE 120 may perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein as being performed by base station 110.

[0029] As mentioned above, Figure 1 is provided as an example. Other examples may differ from Figure 1 Examples described.

[0030] Figure 2 A block diagram of a design 200 of a base station 110 and a UE 120 is shown, which may be Figure 1 Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 254a through 254r, where in general T≥1 and R≥1.

[0031] At the base station 110, the transmit processor 220 may receive data for one or more UEs from the data source 212, select one or more modulation and coding schemes (MCS) for each UE based at least in part on a channel quality indicator (CQI) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the (one or more) MCS selected for each UE, and provide data symbols for all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and the like) and control information (e.g., CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, overhead symbols, and / or reference symbols where applicable, and may provide T output symbol streams to T modulators (MOD) 232a to 232t. Each modulator 232 may process a corresponding output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process the output sample stream (e.g., convert to analog, amplify, filter, and up-convert) to obtain a downlink signal. T downlink signals from modulators 232a to 232t may be transmitted via T antennas 234a to 234t, respectively. According to various aspects described in more detail below, position coding may be used to generate synchronization signals to convey additional information.

[0032] At UE 120, antennas 252a to 252r may receive downlink signals from base station 110 and / or other base stations and may provide received signals to demodulators (DEMODs) 254a to 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols where applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller / processor 280. The channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of UE 120 may be included in a housing.

[0033] On the uplink, at the UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information from a controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.). The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266, if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, uplink signals from the UE 120 and other UEs may be received by the antenna 234, processed by the demodulator 232, detected by the MIMO detector 236, if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to the data sink 239 and provide the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0034] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, or Figure 2Any other component(s) of the base station 110 may perform one or more techniques associated with flexible CSI-RS and SRS association for uplink MIMO, as described in more detail elsewhere herein. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 Any other component(s) may perform or direct e.g. Figure 4 The operations of process 400 and / or other processes as described herein. Memories 242 and 282 may store data and program codes for base station 110 and UE 120, respectively. In some aspects, memory 242 and / or memory 282 may include a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, one or more instructions, when executed by one or more processors of base station 110 and / or UE 120, may perform or direct, for example, Figure 4 The scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0035] In certain aspects, the UE 120 may include: means for determining a set of SRSs based at least in part on a mapping configuration, the mapping configuration being associated with mapping the set of SRSs to a set of CSI-RSs received by the UE, and the set of CSI-RSs being received based at least in part on a set of receive settings, each receive setting being associated with a respective CSI-RS in the set of CSI-RSs; means for determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a respective SRS in the set of SRSs; and means for transmitting the set of SRSs based at least in part on the set of transmit settings; and so on. In certain aspects, such means may include combining Figure 2 One or more components of UE 120 are depicted, such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, etc.

[0036] As mentioned above, Figure 2 is provided as an example. Other examples may differ from Figure 2 Examples described.

[0037] In a wireless communication system, such as an NR system, a spatial relationship between a reference signal and an SRS may be configured (e.g., when a spatialRelationInfo parameter associated with the SRS contains an identifier associated with the reference signal). For example, the reference signal may be a CSI-RS configured on the same serving cell as the serving cell associated with the SRS (e.g., indicated by a servingCellId parameter). According to current standards, for a UE configured with one or more SRS resource configurations, and when the resourceType parameter in the SRS resource is set to "periodic", the UE may be configured with a spatialRelationInfo parameter containing an identifier referring to a "CSI-RS-Index". In such cases, the UE should transmit the SRS using the same spatial filter (i.e., spatial domain transmit filter) as the spatial filter used to receive the associated CSI-RS. Here, only single beam operation is supported on the uplink since such a configuration means that the SRS should be transmitted using the same spatial filter as that associated with receiving the CSI-RS (eg, SRS utilizing multiple ports).

[0038] However, support for multiple beams in the case where SRS is associated with CSI-RS may be useful in many scenarios, such as in partial channel reciprocity scenarios. For example, partial channel reciprocity may exist when downlink transmissions and uplink transmissions are in different component carriers (e.g., in carrier aggregation scenarios), when downlink transmissions and uplink transmissions are in different bandwidth parts, when full beam correspondence does not exist (e.g., where partial beam correspondence results in performance loss and SRS beam scanning can be used to improve partial beam correspondence), or when asymmetric downlink and uplink interference exists (e.g., where uplink interference mitigation can be improved by uplink precoder and / or beam selection).

[0039] Certain aspects described herein provide techniques and apparatus for flexible CSI-RS and SRS association for uplink MIMO. In certain aspects, a UE may determine a set of SRS based at least in part on a mapping configuration associated with mapping a set of SRS to a set of CSI-RS, wherein the set of CSI-RS is received by the UE based at least in part on a set of receive settings. In certain aspects, a UE may determine a set of transmit settings for a set of SRS based at least in part on a set of receive settings, and may transmit a set of SRS based at least in part on a set of transmit settings. Additional details are described below. In certain aspects, the techniques and apparatus described herein are capable of supporting multiple beams on an uplink when an SRS is associated with a CSI-RS, which may be advantageous in, for example, partial channel reciprocity scenarios, as described above.

[0040] Figures 3A-3C is a diagram illustrating an example associated with flexible CSI-RS and SRS association for uplink MIMO according to aspects of the present disclosure. Figure 3A In the embodiment of the present invention, for uplink MIMO transmission, a UE (eg, UE 120) is configured for codebook-based PUSCH transmission, and usage of a set of SRSs is configured to be codebook-based and associated with a set of CSI-RSs, as described above.

[0041] like Figure 3A As shown, and by reference numeral 305, a UE may receive a set of CSI-RS based at least in part on a set of CSI-RS transmitted by a base station (e.g., base station 110). In certain aspects, a UE may receive a set of CSI-RS based at least in part on a set of reception settings, each reception setting being associated with a corresponding CSI-RS in the set of CSI-RS. For example, a UE may receive a first CSI-RS in a set of CSI-RS based at least in part on a first reception setting, may receive a second CSI-RS in a set of CSI-RS based at least in part on a second reception setting, and so on. In certain aspects, a given reception setting associated with a given CSI-RS may include information defining a spatial filter for receiving a given CSI-RS, a beam for receiving a given CSI-RS, a precoder associated with a given CSI-RS, and the like.

[0042] As indicated by reference numeral 310, the UE may determine a set of SRS associated with a set of CSI-RS. In certain aspects, the UE may determine the set of SRS based at least in part on a mapping configuration associated with mapping the set of SRS to the set of CSI-RS.

[0043] In certain aspects, the mapping configuration may indicate that a single SRS in the set of SRSs is to be mapped to a single CSI-RS in the set of CSI-RSs. That is, in certain aspects, the mapping may indicate X (X>1) instances of a 1:1 mapping such that each SRS in the set of SRSs is mapped to a corresponding CSI-RS in the set of CSI-RSs. Examples of such mapping configurations are shown in Figure 3B In the section marked as "Mode 1". Figure 3B In the Mode 1 example in , SRS1 is mapped to CSI-RS1, and SRS2 is mapped to CSI-RS2. In certain aspects, when such a mapping configuration is used, the set of CSI-RS can be configured with a setting parameter "repetition = off", which means that different transmit spatial filters at the base station can be used for different CSI-RS in the transmit set.

[0044] As another example, a mapping configuration may indicate that a single SRS in a set of SRSs is mapped to at least two CSI-RSs in a set of CSI-RSs. That is, in certain aspects, a mapping may indicate an X:1 mapping such that a given SRS in a set of SRSs is mapped to multiple CSI-RSs in a set of CSI-RSs. Examples of such mapping configurations are shown in Figure 3B In the section marked as "Mode 2". Figure 3B In the Mode 2 example in FIG. 1 , SRS1 is mapped to CSI-RS1 to CSI-RSX. In certain aspects, when such a mapping configuration is used, a set of CSI-RS may be configured with a setting parameter “repetition=on”, which means that the same transmit spatial filter at the base station will be used for all CSI-RS in the transmit set.

[0045] As another example, a mapping configuration may indicate that at least two SRSs in a set of SRSs are mapped to a single CSI-RS in a set of CSI-RSs. That is, in certain aspects, the mapping may indicate a 1:X mapping such that multiple SRSs are associated with a given CSI-RS. Examples of such mapping configurations are shown in Figure 3B In the section marked as "Mode 3". Figure 3B In the Mode 3 example in , SRS1 to SRSX are mapped to CSI-RS1.

[0046] In certain aspects, the UE may receive the mapping configuration via, for example, radio resource control (RRC) signaling.In certain aspects, the mapping configuration may be based at least in part on one or more UE capabilities (eg, capabilities associated with the UE's determination of the transmission settings).

[0047] Reference again Figure 3A , as indicated by reference numeral 315, the UE may determine a set of transmit settings, each transmit setting corresponding to a corresponding SRS in the set of SRSs. In certain aspects, the UE may determine the set of transmit settings based at least in part on the set of receive settings associated with the set of received CSI-RSs. For example, the UE may measure the set of CSI-RSs, and based on the mapping configuration, may determine the set of transmit settings for the set of SRSs based at least in part on the set of receive settings and the measurements associated with the set of CSI-RSs. In certain aspects, the transmit settings for a given SRS in the set of SRSs may include information associated with: a spatial filter associated with the given SRS, a beam associated with the given SRS, or a precoder associated with the given SRS, etc.

[0048] In some aspects, one or more SRSs in the set of SRSs may have multiple ports, and each port may be associated with a different transmit setting. In some aspects, the use of multiple ports with different transmit settings may enable determination of uplink ranking based at least in part on the different transmit settings for each transmission of the same SRS from the UE.

[0049] In some aspects, the transmission setting for an SRS in a set of SRSs may be different from the reception setting for a CSI-RS associated with the SRS in a set of CSI-RSs. That is, although the transmission setting for an SRS may be based at least in part on the reception setting for an associated CSI-RS, the transmission setting for an SRS may be different from the reception setting for an associated CSI-RS.

[0050] In certain aspects, the difference between the transmit settings of a given SRS and the receive settings of the associated CSI-RS may be controlled by a configuration received, for example, via RRC signaling.

[0051] In certain aspects, the difference between the transmit settings of a given SRS and the receive settings of an associated SRS can be controlled at least in part based on a threshold (e.g., an RRC-configured threshold, a threshold associated with a measurement of beam correspondence, a threshold associated with precoder correlation, etc.).

[0052] Figure 3C The figure shows an example associated with controlling the difference between the transmission setting and the reception setting. Figure 3C In the example, the transmit settings are constrained to be correlated with the receive settings by a correlation threshold (e.g., an RRC configured correlation threshold). In this example, the required correlation is defined by the following formula:

[0053]

[0054] Where P1 is a receive setting, P2 is a transmit setting, and θ is the difference in beam direction (e.g., angle) between the beam associated with the receive setting and the beam associated with the transmit setting. Here, the transmit setting should be selected so that the conditions defined by the formula are met. It is worth noting that the above formula is provided only as an example, and other examples are possible.

[0055] In certain aspects, controlling the difference between the transmit settings for a given SRS and the receive settings for the associated CSI-RS can enable improved power control (e.g., power fluctuations can be controlled by limiting correlations) and / or improved interference management (e.g., because interference may be caused / uncontrolled if the UE is allowed to arbitrarily change the transmit settings).

[0056] Reference again Figure 3A , and as indicated by reference numeral 320, the UE may transmit a set of SRS based at least in part on the set of transmission settings.

[0057] As indicated by reference numeral 325, the UE may receive uplink downlink control information (DCI) scheduling uplink transmissions (e.g., physical uplink shared channel (PUSCH) transmissions) after transmitting the set of SRSs. For example, after transmitting the set of CSI-RSs, the base station may receive the set of SRSs transmitted by the UE. The base station may measure the set of SRSs, and based on the measurements, may identify the SRSs that use the transmission settings applicable to the uplink transmissions. The base station may then provide an uplink DCI indicating the selected transmission settings (and therefore the selected SRSs) and schedule the uplink transmissions.

[0058] In certain aspects, as described above, the uplink DCI may include information indicating a transmission setting selected for uplink transmission from a set of transmission settings. In certain aspects, the information indicating the transmission setting selected for PUSCH transmission may be an SRS resource indicator (SRI), an uplink transmission configuration indicator (TCI), or another type of indicator carried in the uplink DCI. In certain aspects, the uplink DCI may also indicate a preferred precoder for uplink transmission and a plurality of layers for uplink transmission (TPMI / TRI) and / or another type of information.

[0059] In certain aspects, as shown in reference 330, the UE may send a PUSCH transmission based at least in part on receiving an uplink DCI scheduling the PUSCH transmission. For example, as described above, the UE may identify a transmission setting selected for the PUSCH transmission based at least in part on the uplink DCI, and may send the PUSCH transmission using the selected transmission setting.

[0060] As mentioned above, Figures 3A-3C is provided as an example. Other examples may differ from Figures 3A-3C Examples described.

[0061] Figure 4 is a diagram illustrating an example process 400 performed, for example, by a UE in accordance with aspects of the present disclosure. Example process 400 is an example of operations in which a UE (eg, UE 120, etc.) performs flexible CSI-RS and SRS association for uplink MIMO.

[0062] like Figure 4 As shown, in certain aspects, process 400 may include determining a set of SRSs based at least in part on a mapping configuration, the mapping configuration being associated with mapping a set of SRSs to a set of CSI-RSs received by the UE, and the set of CSI-RSs being received based at least in part on a set of reception settings, each reception setting being associated with a corresponding CSI-RS in the set of CSI-RSs (block 410). For example, as described above, the UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282, etc.) may determine a set of SRSs based at least in part on a mapping configuration. In certain aspects, the mapping configuration is associated with mapping a set of SRSs to a set of CSI-RSs received by the UE. In certain aspects, the set of CSI-RSs may be received based at least in part on a set of reception settings, each reception setting being associated with a corresponding CSI-RS in the set of CSI-RSs.

[0063] like Figure 4 As further shown, in certain aspects, process 400 may include determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a respective SRS in the set of SRSs (block 420). For example, as described above, the UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282, etc.) may determine a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a respective SRS in the set of SRSs.

[0064] like Figure 4 As further shown, in certain aspects, process 400 may include transmitting a set of SRS based at least in part on the set of transmit settings (block 430). For example, as described above, the UE (e.g., using receive processor 258, transmit processor 264, controller / processor 280, memory 282, etc.) may transmit a set of SRS based at least in part on the set of transmit settings.

[0065] Process 400 may include additional aspects, such as any single aspect or any combination of aspects described below and / or in conjunction with one or more other processes described elsewhere herein.

[0066] In the first aspect, the mapping configuration indicates that a single SRS in a set of SRSs is to be mapped to a single CSI-RS in a set of CSI-RSs.

[0067] In a second aspect, alone or in combination with the first aspect, a set of CSI-RS is configured with repetition turned off.

[0068] In a third aspect, alone or in combination with one or more of the first and second aspects, a mapping configuration indicates that a single SRS in the set of SRSs is to be mapped to at least two CSI-RSs in the set of CSI-RSs.

[0069] In a fourth aspect, alone or in combination with one or more of the first to third aspects, a set of CSI-RS is configured with repeated on.

[0070] In a fifth aspect, alone or in combination with one or more of the first to fourth aspects, a mapping configuration indicates that at least two SRSs in a set of SRSs are to be mapped to a single CSI-RS in a set of CSI-RSs.

[0071] In a sixth aspect, alone or in combination with one or more of the first to fifth aspects, the mapping configuration is received via radio resource control signaling.

[0072] In a seventh aspect, alone or in combination with one or more of the first to sixth aspects, the mapping configuration is based at least in part on one or more UE capabilities.

[0073] In the eighth aspect, either alone or in combination with one or more of the first to seventh aspects, the transmission setting for a given SRS in a set of SRSs includes information associated with at least one of: a spatial filter associated with the given SRS, a beam associated with the given SRS, or a precoder associated with the given SRS.

[0074] In a ninth aspect, alone or in combination with one or more of the first to eighth aspects, a transmission setting for an SRS in a set of SRSs is different from a reception setting for a CSI-RS associated with the SRS in a set of CSI-RSs.

[0075] In a tenth aspect, alone or in combination with one or more of the first to ninth aspects, the difference between the transmission setting and the reception setting is controlled by configuration of radio resource control signaling.

[0076] In an eleventh aspect, alone or in combination with one or more of the first to tenth aspects, the difference between the transmit setting and the receive setting is controlled based at least in part on a threshold value.

[0077] In a twelfth aspect, alone or in combination with one or more of the first to eleventh aspects, the threshold is associated with a measure of beam correspondence or precoder correlation.

[0078] In a thirteenth aspect, alone or in combination with one or more of the first to twelfth aspects, at least one SRS in the set of SRSs has a plurality of ports, each port being associated with a different transmission setting.

[0079] In a fourteenth aspect, alone or in combination with one or more of the first to thirteenth aspects, process 400 includes receiving an uplink DCI after transmitting a set of SRS, the uplink DCI scheduling PUSCH transmission and including information indicating a transmission setting selected for PUSCH transmission from a set of transmission settings; a preferred precoder for PUSCH transmission; and multiple layers for PUSCH transmission.

[0080] In a fifteenth aspect, alone or in combination with one or more of the first to fourteenth aspects, the information indicating the transmission setting selected for PUSCH transmission includes at least one of an SRS resource indicator or an uplink transmission configuration indicator.

[0081] Although Figure 4 Example blocks of process 400 are shown, but in some aspects, Figure 4 Process 400 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in . Additionally or alternatively, two or more of the blocks of process 400 may be performed in parallel.

[0082] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the various aspects.

[0083] As used herein, the term "component" is intended to be broadly interpreted as hardware, firmware, and / or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and / or a combination of hardware and software.

[0084] As used herein, satisfying a threshold may refer to a value being greater than a threshold, greater than or equal to a threshold, less than a threshold, less than or equal to a threshold, equal to a threshold, not equal to a threshold, etc., depending on the context.

[0085] It will be apparent that the systems and / or methods described herein may be implemented in various forms of hardware, firmware, and / or combinations of hardware and software. The actual dedicated control hardware or software code used to implement these systems and / or methods is not a limitation of the various aspects. Therefore, the operation and behavior of the systems and / or methods are described herein without reference to specific software code - it should be understood that software and hardware may be designed to implement the systems and / or methods based, at least in part, on the description herein.

[0086] Even if a specific combination of features is stated in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features can be combined in a manner that is not specifically stated in the claims and / or disclosed in the specification. Although each dependent claim listed below can be directly subordinate to only one claim, the disclosure of various aspects includes that each dependent claim is combined with each other claim in the claim set. The phrase "at least one" referring to the list of items refers to any combination of those items, including a single member. As an example, "at least one of a, b or c" is intended to cover a, b, c, ab, ac, bc and abc, and any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc and ccc or any other order of a, b and c).

[0087] Elements, actions or instructions used herein should not be interpreted as critical or necessary unless explicitly described as such. Likewise, as used herein, the article "one" or "an" is intended to include one or more items, and can be used interchangeably with "one or more". In addition, as used herein, the terms "set" and "group" are intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.), and can be used interchangeably with "one or more". In the case of only one item being meant, the phrase "only one" or similar language is used. Likewise, as used herein, the terms "have", "have", "with", etc. are intended to be open terms. In addition, the phrase "based on" is intended to mean "based at least in part on", unless otherwise explicitly stated.

Claims

1. A method for uplink MIMO wireless communication performed by a user equipment (UE), comprising: determining a set of sounding reference signals (SRS) based at least in part on the mapping configuration, The mapping configuration is associated with mapping the set of SRSs to a set of channel state information reference signals (CSI-RSs) received by the UE, and The set of CSI-RS is received based at least in part on a set of reception settings, each reception setting being associated with a respective CSI-RS in the set of CSI-RS; determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a respective SRS in the set of SRSs; as well as transmitting the set of SRS based at least in part on the set of transmission settings, The transmission setting for the SRS in the set of SRSs is different from the reception setting for the CSI-RS associated with the SRS in the set of CSI-RSs, wherein the difference between the transmission setting and the reception setting is controlled at least in part based on a threshold, wherein the threshold is associated with a measurement of beam correspondence or precoder correlation. 2 . The method of claim 1 , wherein the mapping configuration indicates that a single SRS in the set of SRSs is to be mapped to a single CSI-RS in the set of CSI-RSs.

3. The method of claim 2, wherein the set of CSI-RS is configured with repetition off. 4 . The method of claim 1 , wherein the mapping configuration indicates that a single SRS in the set of SRSs is to be mapped to at least two CSI-RSs in the set of CSI-RSs. The method of claim 4 , wherein the set of CSI-RS is configured with repeated on. 6 . The method of claim 1 , wherein the mapping configuration indicates that at least two SRSs in the set of SRSs are to be mapped to a single CSI-RS in the set of CSI-RSs. The method of claim 1 , wherein the mapping configuration is received via radio resource control signaling.

8. The method of claim 1, wherein the mapping configuration is based at least in part on one or more UE capabilities.

9. The method of claim 1 , wherein the transmission settings for a given SRS in the set of SRSs include information associated with at least one of: the spatial filter associated with said given SRS, the beam associated with the given SRS, or A precoder associated with the given SRS.

10. The method of claim 1, wherein the difference between the transmit setting and the receive setting is controlled by configuration of radio resource control signaling.

11. The method of claim 1, wherein at least one SRS in the set of SRSs has a plurality of ports, each port being associated with a different transmission setting.

12. The method of claim 1, further comprising: Receiving uplink downlink control information (DCI) after transmitting the set of SRS, the uplink DCI scheduling physical uplink shared channel (PUSCH) transmission and comprising: information indicating a transmission setting selected for the PUSCH transmission from the set of transmission settings, a preferred precoder for said PUSCH transmission, and A plurality of layers used for the PUSCH transmission.

13. The method of claim 12, wherein the information indicating the transmission setting selected for the PUSCH transmission comprises at least one of: SRS resource indicator, or Uplink transmission configuration indicator.

14. A user equipment (UE) for uplink MIMO wireless communication, comprising: Memory; as well as one or more processors operably coupled to the memory, the memory and the one or more processors being configured to: determining a set of sounding reference signals (SRS) based at least in part on the mapping configuration, The mapping configuration is associated with mapping the set of SRSs to a set of channel state information reference signals (CSI-RSs) received by the UE, and The set of CSI-RS is received based at least in part on a set of reception settings, Each reception setting is associated with a corresponding CSI-RS in the set of CSI-RSs; determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a respective SRS in the set of SRSs; as well as transmitting the set of SRS based at least in part on the set of transmission settings, The transmission setting for the SRS in the set of SRSs is different from the reception setting for the CSI-RS associated with the SRS in the set of CSI-RSs, wherein the difference between the transmission setting and the reception setting is controlled at least in part based on a threshold, wherein the threshold is associated with a measurement of beam correspondence or precoder correlation.

15. A non-transitory computer readable medium storing one or more instructions for uplink MIMO wireless communication, the one or more instructions comprising: One or more instructions that, when executed by one or more processors of a user equipment (UE), cause the one or more processors to: determining a set of sounding reference signals (SRS) based at least in part on the mapping configuration, The mapping configuration is associated with mapping the set of SRSs to a set of channel state information reference signals (CSI-RSs) received by the UE, and The set of CSI-RS is received based at least in part on a set of reception settings, Each reception setting is associated with a corresponding CSI-RS in the set of CSI-RSs; determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a respective SRS in the set of SRSs; as well as transmitting the set of SRS based at least in part on the set of transmission settings, The transmission setting for the SRS in the set of SRSs is different from the reception setting for the CSI-RS associated with the SRS in the set of CSI-RSs, wherein the difference between the transmission setting and the reception setting is controlled at least in part based on a threshold, wherein the threshold is associated with a measurement of beam correspondence or precoder correlation.

16. An apparatus for uplink MIMO wireless communication, comprising: means for determining a set of sounding reference signals (SRS) based at least in part on the mapping configuration, The mapping configuration is associated with mapping the set of SRSs to a set of channel state information reference signals (CSI-RSs) received by the apparatus, and The set of CSI-RS is received based at least in part on a set of reception settings, each reception setting being associated with a respective CSI-RS in the set of CSI-RS; means for determining a set of transmit settings based at least in part on the set of receive settings, each transmit setting corresponding to a respective SRS in the set of SRSs; as well as A component for transmitting the set of SRSs based at least in part on the set of transmit settings, wherein the transmit settings for the SRSs in the set of SRSs are different from the receive settings for the CSI-RSs associated with the SRSs in the set of CSI-RSs, wherein the difference between the transmit settings and the receive settings is controlled at least in part based on a threshold, wherein the threshold is associated with a measurement of beam correspondence or precoder correlation.

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