Method, apparatus, and system for sounding reference signal antenna switching

Abstract

Disclosed herein are methods, apparatus, systems, etc. directed to sounding reference signal (SRS) antenna switching. In one embodiment, a WTRU may transmit information indicating the presence of a sounding reference signal (SRS) power imbalance for at least one transmit and receive (xTyR) antenna configuration in a set of xTyR antenna configurations. For example, the WTRU may receive a request to report SRS power imbalance information. For example, the WTRU may transmit, for at least one SRS resource set associated with the at least one xTyR antenna configuration, SRS power imbalance information indicating (i) one or more affected SRS resources in the at least one SRS resource set and (ii) one or more power imbalance values ​​for the one or more affected SRS resources.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of (i) U.S. Provisional Patent Application No. 63 / 136,329, filed January 12, 2021, (ii) U.S. Provisional Patent Application No. 63 / 228,720, filed August 3, 2021, and (iii) U.S. Provisional Patent Application No. 63 / 248,689, filed September 27, 2021, the contents of each of which are incorporated herein by reference. [Background technology]

[0002] The present disclosure relates to network communications, including, but not limited to, methods, apparatus, systems, etc. directed to antenna switching in wireless networks. Summary of the Invention

[0003] SUMMARY Disclosed herein are methods, apparatus, systems, etc. directed to sounding reference signal (SRS) antenna switching.

[0004] In one embodiment, a WTRU may transmit information indicating the presence of a sounding reference signal (SRS) power imbalance for at least one transmit and receive (xTyR) antenna configuration in a set of xTyR antenna configurations. For example, the WTRU may receive a request to report SRS power imbalance information. For example, the WTRU may transmit, for at least one SRS resource set associated with the at least one xTyR antenna configuration, SRS power imbalance information indicating (i) one or more affected SRS resources in the at least one SRS resource set and (ii) one or more power imbalance values ​​for the one or more affected SRS resources.

[0005] In one embodiment, SRS antenna switching may be performed in either a first mode of operation or a second mode of operation. When the WTRU is operating in the first mode, SRS antenna switching may be performed according to the transmit (Tx) and receive (Rx) dimensions of the WTRU. When the WTRU is operating in the second mode of operation, SRS antenna switching may be performed according to the WTRU coherence capability and Rx dimension. For example, in the second mode of operation, a subset (e.g., only) of the available Tx chains may be used for SRS transmission at a time. For example, in the second mode of operation, SRS antenna switching may be performed for one subset of Tx chains while a transmission is ongoing on another subset of Tx chains.

[0006] Although various embodiments are described and / or claimed herein in which apparatus, systems, devices, etc., and / or any elements thereof are configured to perform an operation, process, algorithm, function, etc., and / or any portion thereof, it should be understood that any embodiment described and / or claimed herein assumes that any apparatus, system, device, etc., and / or any element thereof performs any operation, process, algorithm, function, etc., and / or any portion thereof (and vice versa). [Brief explanation of the drawings]

[0007] A more detailed understanding may be had from the following detailed description, given by way of example in conjunction with the accompanying drawings. The figures of such drawings, like the detailed description, are examples. Therefore, the figures and detailed description should not be considered limiting, as other equally effective examples are possible and likely. Also, like reference numerals in the figures indicate like elements. [Figure 1A] FIG. 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B]1B is a system diagram illustrating an exemplary wireless transmit / receive unit (WTRU) that may be used within the communication system shown in FIG. 1A, according to one embodiment. [Figure 1C] 1B is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system shown in FIG. 1A, according to one embodiment. [Figure 1D] 1B is a system diagram illustrating a further exemplary RAN and a further example of a CN that may be used within the communication system shown in FIG. 1A, according to one embodiment. [Figure 2] FIG. 1 illustrates an example of SRS transmission for downlink channel estimation in a time division duplex system. [Figure 3] FIG. 2 illustrates an example of a WTRU Rx / Tx architecture with four Rx antennas and two Tx antennas. [Figure 4] FIG. 10 illustrates an example of transmit antenna switching in a 2T4R WTRU. [Figure 5] FIG. 10 illustrates an example of SRS antenna port mapping for a 4T8R WTRU. [Figure 6] FIG. 2 illustrates an example of a hybrid mode of operation of a WTRU according to Mode 1 and Mode 2. [Figure 7] FIG. 10 illustrates an example of SRS transmission using one of the coherent transmission groups for a 4T8R PNC WTRU. [Figure 8] FIG. 10 illustrates an example of antenna switching for SRS transmission for a 4T8R PNC WTRU in which both coherent transmission groups may be used. [Figure 9] FIG. 10 shows an example of antenna switching for SRS transmission for a 4T8R NC WTRU in which four coherent transmission groups may be used. [Figure 10]FIG. 10 illustrates an example of antenna switching for SRS transmission for a 4T8R PNC WTRU in which both coherent transmission groups may be used. [Figure 11] FIG. 10 shows an example of SRS antenna port mapping for a 4T6R WTRU using one of a subset of Tx chains. [Figure 12] FIG. 10 shows an example of SRS antenna port mapping for a 4T6R WTRU using both subsets of Tx chains. [Figure 13] FIG. 10 shows an example of SRS antenna port mapping for a 4T6R WTRU using a full subset of Tx chains. [Figure 14] FIG. 10 shows another example of SRS antenna port mapping for a 4T6R WTRU using a full subset of Tx chains. [Figure 15] FIG. 1 illustrates an example method for SRS antenna switching. [Figure 16A] FIG. 10 illustrates an example of transmission of a first SRS resource with SRS antenna switching for a 4T6R WTRU. [Figure 16B] FIG. 10 illustrates an example of transmission of a second SRS resource with SRS antenna switching for a 4T6R WTRU. [Figure 16C] FIG. 10 illustrates an example of transmission of a third SRS resource with SRS antenna switching for a 4T6R WTRU. [Figure 17] FIG. 10 illustrates an example of a power imbalance reporting indication for a 4T6R WTRU. [Figure 18] 1 illustrates a first example of a method for WTRU-assisted SRS power imbalance compensation. [Figure 19] FIG. 10 illustrates a second example of a method for WTRU-assisted SRS power imbalance compensation. [Figure 20] FIG. 1 illustrates an example method for WTRU-based SRS power imbalance compensation. DETAILED DESCRIPTION OF THE INVENTION

[0008] A detailed description of illustrative embodiments will now be described with reference to various figures. While the description provides detailed examples of possible implementations, it should be noted that the details are intended to be illustrative and in no way limit the scope of the present application. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples can be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the following description. Furthermore, embodiments and examples not specifically described herein can be practiced in place of, or in combination with, embodiments and other examples explicitly, implicitly, and / or inherently described, disclosed, or otherwise provided herein (collectively "provided").

[0009] Exemplary Communication Network 1A illustrates an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. Communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, broadcasts, etc., to multiple wireless users. Communication system 100 may enable multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), etc.

[0010] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station" and / or "STA," may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., remote surgery), an industrial device and application (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain situations), a consumer electronics device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a UE.

[0011] The communications system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNodeB, a Home Node B, a Home eNodeB, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, etc. Although the base stations 114a, 114b are each shown as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0012] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers per sector of the cell, for example, using beamforming to transmit and / or receive signals in desired spatial directions.

[0013] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0014] More specifically, as noted above, the communications system 100 may be a multiple-access system and may use one or more channel access schemes, such as, for example, CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114 a and the WTRUs 102 a, 102 b, 102 c in the RAN 104 / 113 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communications protocols such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​Uplink Packet Access (HSUPA).

[0015] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-Advanced, LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0016] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0017] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE radio access and NR radio access, e.g., using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0018] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity, WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access, WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0019] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point and may utilize any suitable RAT to facilitate wireless connectivity in a local area such as a location such as a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may establish a picocell or a femtocell using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 through the CN 106 / 115.

[0020] The RAN 104 / 113 may communicate with the CN 106 / 115, which may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as different throughput, latency, error tolerance, reliability, data throughput, and mobility requirements. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calls, Internet connectivity, video distribution, and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 may communicate directly or indirectly with other RANs employing the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown) employing GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0021] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a public switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP Internet protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0022] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links.) For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may use a cellular-based wireless technology and a base station 114b that may use an IEEE 802 wireless technology.

[0023] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0024] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0025] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0026] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0027] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0028] The processor 118 of the WTRU 102 may be coupled to and may receive user-entered data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Additionally, the processor 118 may access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0029] The processor 118 may receive power from the power source 134, but may also be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0030] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0031] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0032] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and downlink (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and or substantially eliminating self-interference through either hardware (e.g., chokes) or processor-mediated signal processing (e.g., via a separate processor (not shown) or processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for transmission and reception of either some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or downlink (e.g., for reception)).

[0033] 1C is a system diagram illustrating the RAN 104 and the CN 106 according to one embodiment. As mentioned above, the RAN 104 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using E-UTRA radio technology. The RAN 104 may also communicate with the CN 106.

[0034] The RAN 104 may include eNodeBs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In an embodiment, the eNodeBs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNodeB 160a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0035] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling, etc. in the UL and / or DL. As shown in FIG. 1C, the eNodeBs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0036] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is illustrated as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0037] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM and / or WCDMA.

[0038] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNode-B handovers, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0039] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0040] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional landline communications devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0041] Although the WTRU is depicted in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments, such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

[0042] In a representative embodiment, the other network 112 may be a WLAN.

[0043] A WLAN in infrastructure Basic Service Set (BSS) mode may have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating from outside the BSS to a STA may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP and transmitted to the respective destination. Traffic between STAs within the BSS may be transmitted, for example, through the AP; the source STA may send traffic to the AP, which may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be transmitted between a source STA and a destination STA (e.g., directly between them) in a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (e.g., all of the STAs) may communicate directly with each other. The IBSS mode of communication may be referred to herein as an "ad hoc" communication mode.

[0044] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width that is dynamically set via signaling. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0045] High Throughput (HT) STAs may use 40 MHz wide channels for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0046] A Very High Throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz and / or 80 MHz wide channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may pass through a segment parser that may split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing may be performed separately on each stream. The streams may be mapped to two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed, and the combined data may be transmitted to the Medium Access Control (MAC).

[0047] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support meter-type control / machine-type communications, such as MTC devices within macro coverage areas. MTC devices may have specific capabilities, including, for example, support for (e.g., only for) specific and / or limited bandwidths. MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0048] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that can be designated as a primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be configured and / or limited by the STAs among all STAs operating in the BSS that support the minimum bandwidth operating mode. In an 802.11ah example, the primary channel can be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) configuration can depend on the condition of the primary channel. For example, if the primary channel is busy due to a STA (that only supports 1 MHz mode of operation) transmitting to the AP, the entire available frequency band may be considered busy, even though most of the frequency band may remain idle and be available for use.

[0049] In the United States, the available frequency band that can be used by 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz depending on the country code.

[0050] 1D is a system diagram illustrating the RAN 113 and the CN 115 according to one embodiment. As mentioned above, the RAN 113 may communicate with the WTRUs 102a, 102b, 102c over the air interface 116 using NR radio technology. The RAN 113 may also communicate with the CN 115.

[0051] The RAN 113 may include gNBs 180a, 180b, and 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a and 180b may utilize beamforming to transmit and / or receive signals to and / or from the WTRUs 102a, 102b, and 102c. Thus, the gNB 180a may, for example, transmit wireless signals to and / or receive wireless signals from the WTRU 102a using multiple antennas. In one embodiment, the gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, and the remaining component carriers may be on a licensed spectrum. In one embodiment, the gNBs 180a, 180b, and 180c may implement Coordinated Multi-Point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0052] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., including varying numbers of OFDM symbols and / or varying lengths of absolute time).

[0053] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNodeBs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate with and connect to gNBs 180a, 180b, 180c while also communicating with and connecting to another RAN, such as eNodeBs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, while the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0054] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D , the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0055] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements is illustrated as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0056] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize the CN support of the WTRUs 102a, 102b, 102c based on the type of service utilizing the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. The AMF 182 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0057] The SMFs 183a and 183b may be connected to the AMFs 182a and 182b in the CN 115 via an N11 interface. The SMFs 183a and 183b may also be connected to the UPFs 184a and 184b in the CN 115 via an N4 interface. The SMFs 183a and 183b may select and control the UPFs 184a and 184b and configure the routing of traffic through the UPFs 184a and 184b. The SMFs 183a and 183b may perform other functions, such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0058] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks such as the Internet 110 to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184a, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policy, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0059] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0060] 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-ab, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or simulate network and / or WTRU functions.

[0061] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more or all functions while temporarily implemented or deployed as part of a wired and / or wireless communication network. The emulation devices may be directly coupled to another device for testing purposes and / or may perform testing using terrestrial wireless communication.

[0062] One or more emulation devices may perform one or more functions, inclusive, while not being implemented or deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in an undeployed (e.g., test) wired and / or wireless communication network to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, e.g., one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0063] Examples of SRS-based methods For example, a sounding reference signal (SRS) may be used for uplink channel measurements. In another example, SRS transmission may be used to assist downlink channel state information (CSI) estimation for either partial and (e.g., fully) reciprocal channels. In yet another example, SRS may be used for beam management. SRS may be transmitted through different SRS resources to support beam selection by a network element (e.g., a gNB). The embodiments described herein may enable improved MIMO performance, for example, by enabling dynamic and flexible sounding procedures with appropriate capacity and coverage. Throughout the embodiments described herein, the terms “serving base station,” “base station,” and “gNB” may be used interchangeably to designate a network element acting as a serving base station. The embodiments described herein are not limited to gNBs and are applicable to any other type of serving base station.

[0064] Mobile communications are continuously evolving and are already on the verge of its fifth incarnation, called the fifth generation, which may be referred to herein as 5G, NR, or collectively as NR. In NR Release 16, a WTRU may be configured with (e.g., may receive configuration information indicating) any number of SRS resource sets (which may be referred to herein as SRS-ResourceSet). An SRS resource set may include up to K SRS resources, where K may be an integer and may be based on WTRU capabilities. An SRS resource set may be configured for different applications (e.g., usages), such as beam management, codebook, non-codebook, or antenna switching. For example, the time-domain behavior of the SRS resource configuration may be indicated by a (e.g., higher layer) parameter resourceType. For example, the time-domain behavior may be configured (e.g., indicated as configuration information) as periodic (e.g., regular), semi-persistent, or aperiodic. In NR Release 16, a WTRU may not be configured to have different time domain behaviors, e.g., periodic, semi-persistent, etc. In NR Release 16, a WTRU may not be configured to have different periodicities for SRS resources within the same SRS resource set.

[0065] For example, an aperiodic SRS may have a higher transmission priority than both periodic and semi-persistent SRS if the aperiodic SRS is transmitted (e.g., triggered to be transmitted) on the same symbol. For example, an aperiodic SRS may have a higher priority than a physical uplink control channel (PUCCH) if the aperiodic SRS is transmitted (e.g., triggered to be transmitted) on the same symbol, except, for example, when the PUCCH carries any of a hybrid automatic repeat request acknowledge (HARQ-ACK), a link recovery request, and a schedule request (SR).

[0066] Example of SRS Transmission for Downlink CSI Estimation According to an embodiment, the application of the SRS may be to estimate downlink CSI. The terms "channel," "channel CSI," and "CSI," collectively CSI, may be used interchangeably. In a time division duplex (TDD) system, for example, based on the principle of channel reciprocity, the SRS may be used herein as the downlink CSI.

[0067]

number

[0068]

number

[0069]

number

[0070] 2 shows an example of SRS transmission for downlink CSI estimation in a TDD system. Considering that in a frequency division duplex (FDD) system, the separation between uplink and downlink frequencies may be limited, a similar process can be used to obtain some information about the downlink CSI information, such as the channel covariance matrix.

[0071] For example, a WTRU may be equipped with the same number of transmit (Tx) and receive (Rx) antennas, and (e.g., each) antenna may be (e.g., always) connected to (e.g., the same) receive and transmit signal chains. For a WTRU, SRS signal transmission for CSI estimation may be performed in a simple manner (e.g., without considering receive and transmit signal chain variations).

[0072] Throughout the embodiments described herein, the terms "transmit," "transmitting," and collectively "Tx" may be used interchangeably. Throughout the embodiments described herein, the terms "receive," "receiving," and collectively "Rx" may be used interchangeably.

[0073] Example of transmitting antenna switching For SRS antenna switching, the WTRU may be configured with any number of SRS resource sets having a usage parameter (e.g., usage=antennaSwitching) indicating antenna switching. For example, (e.g., each) SRS resource set may be configured with any number of SRS resources, e.g., according to the number of WTRU antenna ports. For example, the SRS resource may be (e.g., a set of) time and frequency resources transmitted for channel sounding. For example, the SRS resource may be configured by an SRS resource information element and may include any of several antenna ports, several consecutive OFDM symbols (e.g., a sequence), time resources, and frequency resources. In NR Release 16, several xTyR configurations for SRS antenna switching may be considered (where x and y are integers, e.g., x={1,2} and y={1,2,4}). For example, an SRS resource set may be associated with an antenna configuration for SRS antenna switching. In a 1T2R example, up to two resource sets may be configured, where each set may have (e.g., include) two SRS resources transmitted on different symbols, where each SRS resource in a given set may include a single SRS port, and the SRS port of a second resource in the set may be associated with a different antenna port than the SRS port of a first resource in the same set, resulting in two different SRS resource sets associated with two different antenna configurations. More generally, two or more resource sets may be configured (e.g., indicated via configuration information), where a set may have (e.g., include) any number of SRS resources transmitted on different symbols, and where (e.g., each) SRS resource in a given set may include any number of SRS ports. Different SRS resource sets may be associated with different antenna configurations for SRS antenna switching, where, for example, the SRS port of a first resource in a first SRS resource set may be associated with a different antenna port than the first resource in a second SRS resource set.

[0074] Throughout the embodiments described herein, the terms "antenna configuration", "antenna configuration for SRS antenna switching", and "xTyR antenna configuration" are used interchangeably to designate an antenna configuration for SRS antenna switching and may refer to a set of antenna ports that can be used as either a Tx antenna port or a Rx antenna port depending on different switching configurations.

[0075] Throughout the embodiments described herein, the terms "SRS transmission", "transmitted SRS", "SRS resource transmission", and "transmitted SRS resource" may be used interchangeably to designate a transmission (e.g., sounding reference signal) that can be transmitted on an SRS (e.g., time / frequency) resource.

[0076] FIG. 3 is a diagram illustrating an example of a WTRU Rx / Tx architecture (2T4R WTRU) having four Rx antennas and two Tx antennas. As shown in FIG. 3, two of the four available Rx antennas 301, 302, 303, 304 can be connected to the Tx chains 311, 312 at one time. Transmit antenna switching that can switch the available Tx chains 311, 312 of the WTRU to different Rx antennas 301, 302, 303, 304 within the WTRU may enable SRS-based downlink CSI estimation in a WTRU having an xTyR (x < y) architecture.

[0077] FIG. 4 is a diagram illustrating an example of antenna switching in a 2T4R WTRU. For example, the first Tx chain 41 may be switchable (e.g., between) (e.g., sequentially) between two different antennas 401, 402 of a first set of antennas, and the second Tx chain 42 may be switchable (e.g., between) (e.g., sequentially) between two different antennas 403, 404 of a second set of antennas to support the transmission of SRS from all antennas that can be used for reception.

[0078] In NR Release 17, SRS antenna switching for up to eight Rx antennas may be supported. Configurations supported in NR Release 17 may include any of 1T6R, 1T8R, 2T6R, 2T8R, 4T6R, and 4T8R. For example, selection criteria for the SRS switching configuration may include any of CSI latency and performance considerations, such as insertion loss, use case, antenna structure, WTRU power saving, SRS resource configuration, etc.

[0079] For example, a WTRU may comprise one or more Tx chains that may be switchable to one or more antenna ports. For example, an xTyR antenna configuration may comprise (e.g., associated with) one or more Tx chains coupled to (e.g., associated with, switched to) one or more antenna ports.

[0080] WTRU Coherence Capability Example According to an embodiment, a Tx chain may have an amplitude and phase response. For example, a Tx chain may be considered as a filter that may have an amplitude and phase response. Throughout the embodiments described herein, (e.g., at least) two coherent Tx chains may be viewed as (e.g., at least) two Tx chains that exhibit (e.g., very) similar amplitude and phase responses. In other words, for the same test signal input to the Tx chains, the output of the coherent Tx chain may exhibit (e.g., output a test signal having) negligible deviations in amplitude and phase, and the output of the non-coherent Tx chain may exhibit (e.g., output a test signal having) non-negligible deviations in amplitude and phase.

[0081] In NR Release 15, three different transmit capabilities have been introduced to improve uplink transmission reliability. The WTRU transmit capabilities may reflect the integrity of the uplink Tx chain with respect to either phase or time coherency that may result from impairments. The WTRU transmit capabilities may include nonCoherent (NC), partialAndNonCoherent (PNC), and fullAndPartialAndNonCoherent (FPNC).

[0082] In an FPNC WTRU, all Tx chains may be coherent, eg, for the same test signal input to the Tx chains, all Tx chains may exhibit negligible deviation in amplitude and phase.

[0083] In a NC WTRU, for the same test signal input to the Tx chain, the output of any of the Tx chains may exhibit non-negligible deviations in amplitude and phase.

[0084] In a PNC WTRU, a subset of the Tx chains may be considered to have coherent Tx chains. The PNC WTRU may comprise non-coherent Tx chains. For example, the PNC WTRU may include a different subset of coherent Tx chains, and the Tx chains of the different subsets may be non-coherent.

[0085] Reporting the WTRU transmission capabilities may enable adapting precoding operations based on the coherence level of the WTRU transmission architecture. For example, a specific subset of precoders (e.g., only) may be allowed (e.g., selected) for transmission based on (e.g., potential) phase / amplitude imbalance between different Tx chains corresponding to the indicated WTRU coherence capabilities.

[0086] According to embodiments, the SRS may be used to estimate downlink CSI through uplink (e.g., transmission) measurements. WTRU coherence capability may affect the integrity of the uplink transmission. Embodiments described herein may enable performing SRS antenna switching for downlink CSI estimation based on the WTRU coherence capability.

[0087] Without loss of generality, embodiments are described herein using a 4T8R WTRU. The embodiments described herein are equally applicable to any other (e.g., xTyR) WTRU configurations of any other Tx / Rx dimensions (e.g., having any number of Tx and Rx chains). Throughout the embodiments described herein, the terms “coherent transmission group,” “coherent transmission chain (e.g., group thereof),” “coherent group,” “SRS coherent antenna port group,” and “coherent SRS antenna port group” may be used interchangeably to designate a set of coherent Tx chains.

[0088] 5 is a diagram illustrating an example of SRS antenna port mapping for a 4T8R (e.g., FPNC) WTRU. For example, the WTRU may be configured with an SRS resource set including, for example, four SRS resources. For example, in (e.g., each) transmission (e.g., event), the four SRS resources may be transmitted using four (e.g., available) Tx chains. For example, in a first transmission (e.g., event) 51, the four Tx chains may be connected to a first set of antenna ports, e.g., (0, 1, 2, 3), and in a second transmission (e.g., event) 52, they may be connected to a second set of antenna ports, e.g., (4, 5, 6, 7).

[0089] Operation mode examples In one embodiment, for example, a WTRU having an xTyR antenna configuration may perform (e.g., may be configured to perform) SRS antenna switching in either a first mode of operation or a second mode of operation according to (e.g., indicated) WTRU coherence capability. In the first mode of operation (sometimes referred to herein as Mode 1), the WTRU may perform SRS antenna switching according to the Tx and Rx dimensions (e.g., the number of Tx and Rx chains, e.g., x and y). In the second mode of operation (sometimes referred to herein as Mode 2), the WTRU may perform SRS antenna switching according to (e.g., indicated) WTRU coherence capability and the Rx dimension (e.g., the number of antennas). For example, SRS antenna switching may be performed according to the number of coherent Tx chains and the number of Rx chains (sometimes referred to herein as x_coh).

[0090] According to an embodiment, for example, a WTRU having an xTyR antenna configuration may report (e.g., transmit an indication report) either its NC and PNC coherent capabilities. For example, the WTRU may indicate (e.g., transmit information indicative of) the number of coherent Tx chains (x_coh), which may be less than the number of Tx chains (x). For example, the WTRU may indicate (e.g., transmit information indicative of) the number of (e.g., coherent) groups containing, e.g., (x_coh) coherent Tx chains.

[0091] According to an embodiment, the WTRU may perform SRS antenna switching according to its (eg, indicated) coherence capability.

[0092] For example, if a WTRU reports its coherence capability as FPNC (e.g., transmits information indicating same), the WTRU may perform SRS antenna switching according to Mode 1, e.g., the WTRU may perform SRS antenna switching according to the WTRU Tx / Rx dimension, e.g., the number of Tx and Rx chains (x and y).

[0093] For example, if a WTRU reports its coherence capability as either NC or PNC (e.g., transmits information indicating same), the WTRU may perform antenna switching according to either Mode 1 or Mode 2, and the dimension pairs (x, y) and (x_coh, y) may be considered for SRS antenna switching, respectively. In other words, if the WTRU operates in Mode 2, the WTRU may perform SRS antenna switching based on the number of coherent Tx chains (x_coh) and the number of Rx chains (y). If the WTRU operates in Mode 1, the WTRU may perform SRS antenna switching based on the number of (e.g., all) Tx chains (x) and the number of Rx chains (y).

[0094] For example, if a WTRU reports (e.g., transmits information indicating) its coherence capability as either NC or PNC, the WTRU may indicate (e.g., transmit an indication of) the number of coherent Tx chains (x_coh) that the WTRU may support. For example, the indication of the number of coherent Tx chains (x_coh) may be transmitted either in the same information element (e.g., message) as the WTRU coherence capability or in a separate information element (e.g., message). For example, the WTRU may receive (e.g., as a default configuration) either a dynamic or semi-static value for the number of coherent Tx chains (x_coh), e.g., through Layer 1, Layer 2, or radio resource control (RRC) signaling. A WTRU that may have received the number of coherent Tx chains (x_coh) may not report the number of coherent Tx chains (x_coh). If a WTRU receives a (e.g., default) configuration (e.g., including x_coh) after indicating its number of coherent Tx chains (x_coh), the received default configuration may override the x_coh value indicated by the WTRU.

[0095] For example, if a WTRU reports (e.g., transmits information indicating) its coherence capability as either NC or PNC, for example, without indicating the number of coherent Tx chains (x_coh), the number of coherent Tx chains (x_coh) may be considered (e.g., by the gNB) to be equal to a default value. For example, the default value may be fixed. In another example, the default value may be pre-configured. For example, the default value may be 2 plus the number of Tx chains (x).

[0096] For example, a WTRU may select between Mode 1 and Mode 2 based on either its operating configuration or its transmission characteristics. For example, either a PNC or NC WTRU with high mobility may select Mode 1 since potential distortion in the downlink CSI may not be significant due to other impairments, e.g., high Doppler, stale CSI, etc.

[0097] Hybrid example between Mode 1 and Mode 2 According to an embodiment, Mode 1 may allow a WTRU to transmit (e.g., simultaneously) on (e.g., all) Tx chains, as shown in FIG. 5. Operating in Mode 1 may require less time to transmit all SRS ports and provide channel estimates compared to Mode 2, which may transmit SRS simultaneously using (e.g., only) coherent Tx chains. Mode 2 may improve the accuracy of the channel representation by taking into account the coherence capabilities between Tx chains. Mode 2 may involve more slots to complete transmission across all transmission dimensions (e.g., compared to Mode 1) because the coherent Tx chains may be (e.g., only) a subset of all Tx chains.

[0098] According to an embodiment, the WTRU may perform (eg, decide to perform) SRS antenna switching in a hybrid pattern that includes operating in Mode 1 and Mode 2.

[0099] FIG. 6 illustrates an example of a hybrid mode of operation of a WTRU according to Mode 1 and Mode 2. For example, the WTRU may alternate between switching (e.g., antennas) in Mode 1 and switching (e.g., antennas) in Mode 2. FIG. 6 illustrates a pattern that includes operating in Mode 2 for N2=1 instances (e.g., of opportunity) followed by operating in Mode 1 for N1=2 instances (e.g., of opportunity). For example, the pattern may be repeated by starting over again in Mode 2. During Mode 2 instance 621 (e.g., of opportunity), the WTRU may perform SRS switching according to two coherent Tx chains (e.g., initially connected to APs 0 and 1). To complete a transmission for the eighth AP, four consecutive transmissions may be performed by the WTRU. During Mode 1 instances 611, 612 (e.g., of opportunity), the WTRU may perform SRS antenna switching according to the total transmission dimension. For example, a WTRU may transmit to APs 0, 1, 2, and 3 (e.g., simultaneously), where the pair of Tx chains connected to (0, 1) may be pair-coherent, and the pair of Tx chains connected to (2, 3) may be pair-coherent, but the Tx chains between the pairs may not be coherent.

[0100] According to an embodiment, a switching pattern (eg, as shown in FIG. 5) may represent any combination of Mode 1 and Mode 2 operation over any number of instances (eg, of opportunity).

[0101] According to an embodiment, the WTRU may obtain (e.g., determine) the switching pattern based on either a timer or a counter. For example, the switching pattern may be obtained based on a period during which the WTRU may perform antenna switching by alternating between operating in Mode 1 during a first time interval (e.g., T1 seconds) and operating in Mode 2 during a second time interval (e.g., T2 seconds). The time interval values ​​(T1, T2) may be either semi-statically configured or pre-configured. In another example, the pattern may be obtained according to a first number N1 of opportunities for operating in Mode 1 and a second number N2 of opportunities for operating in Mode 2 during a time period such as that shown in FIG. 6. The first and second numbers of opportunities (N1, N2) may be either semi-statically configured or pre-configured.

[0102] According to an embodiment, the activity pattern may represent any portion of a switching pattern that may be used by the WTRU.

[0103] According to an embodiment, the WTRU may obtain (e.g., determine) an activity pattern that may be associated with a switching pattern. For example, the switching pattern may be statically configured as shown in FIG. 6. For example, the WTRU may obtain (e.g., determine) the activity pattern based on dashed boxes 61, 62, which may indicate portions of the switching pattern that the WTRU may use to transmit SRS. For example, the WTRU may obtain (e.g., determine) from the activity pattern which of the modes to use. For example, the WTRU may determine to be active for (e.g., only for) Mode 1 portion (e.g., gray box) 61 of the pattern. For example, the WTRU may be in a silent state during Mode 2 portion 62 of the pattern.

[0104] According to an embodiment, the activity pattern may vary (e.g., may be obtained) based on either a semi-static configuration or a dynamic indication (e.g., received by any of L1, L2, and RRC signaling). For example, the activity pattern may switch (e.g., may change) depending on any of the SRS configuration, traffic priority (e.g., Mode 1 for URLLC, Mode 2 for eMBB), the RRC state of the WTRU, the WTRU speed, etc. For example, the activity pattern may be defined across modes. For example, the activity pattern may include an instance of Mode 1 and an instance of Mode 2.

[0105] According to an embodiment, the WTRU may adjust either the panel on / off pattern, the beam switching time, and may transmit the SRS according to a pattern between Mode 1 and Mode 2 (eg, alternating).

[0106] According to an embodiment, at the receiver, a total radiating power (TRP) may determine, e.g., using a configured pattern, a switching pattern that may have been used by the WTRU at a (e.g., given) time. The TRP may switch its Rx filters depending on which operating mode may be used by the WTRU.

[0107] For example, the TRP may provide a weighting factor to determine the overall channel estimate. For example, a channel estimate provided in Mode 2 using a coherent Tx chain pair group (sometimes referred to herein as H2) may be given a different weight compared to a channel estimate provided by Mode 1 (sometimes referred to herein as H1). For example, if the samples are time-averaged, the samples may be weighted differently based on H ave =αH1+(1−αH2), where H ave may be the time-averaged channel, and α may be a weighting factor between the channels obtained in mode 1 and mode 2.

[0108] In another example, the TRP may obtain separate channels H1 and H2, where each channel may be used in a different application, for example. For example, for a high channel accuracy application, the TRP may decide to use H2, and for a low latency application, the TRP may use the H1 estimate.

[0109] Antenna switching example in mode 2 According to an embodiment, a WTRU may be considered as (e.g., correspond to) a set of coherent transmission groups, where the Tx dimension for SRS transmission may be the number of coherent Tx chains (x_coh). For example, a 4Tx PNC WTRU may be considered as (e.g., correspond to) a set of two coherent transmission groups. In another example, a 4Tx NC UE may be considered as (e.g., correspond to) a set of four coherent transmission groups (e.g., with a single Tx chain in (e.g., each) group). In yet another example, a 4Tx FPNC WTRU (due to its full coherent capability) may be considered as (e.g., correspond to) any set of coherent transmission groups of any number of Tx chains, e.g., two groups of two coherent Tx chains (2+2), two groups of one Tx chain each and three coherent Tx chains (1+3), etc.

[0110] Example using one of the coherent transmission groups According to an embodiment, either the PNC or the NC WTRU may use one (e.g., only) of its coherent transmission groups for transmission at (e.g., a given time), e.g., to avoid distortion in SRS transmissions.

[0111] 7 illustrates an example of SRS transmission using one of the coherent transmission groups for a 4T8R PNC WTRU. According to an embodiment, the same pair of coherent Tx chains may be sequentially switched to, for example, different pairs of antennas. For example, the WTRU may select one of the (e.g., available) coherent transmission groups, where the dimension of the SRS transmission may be, for example, x_coh=2. In the illustrated example, the selected coherent transmission group may be one of the pairs of coherent Tx chains. Using the selected coherent transmission group, the WTRU may transmit SRS using, for example, two of the SRS resources of the configured SRS resource set in (e.g., each) transmission (e.g., event) 71, 72, 73, 74. In the illustrated example, for (e.g., each) transmission (e.g., event) 71, 72, 73, 74, a different pair of antenna ports may be used (e.g., connected to a pair of coherent Tx chains, e.g., (0,1), (4,5), (2,3), (6,7)). According to an embodiment, the WTRU may separate the SRS transmissions (e.g., events) by applying a guard time 70, e.g., to allow for antenna switching.

[0112] Example of using any number of coherent transmission groups According to an embodiment, either the PNC or the NC WTRU may use any number (e.g., two or more) of its coherence groups for SRS transmission, and according to an embodiment, may use one (e.g., only one) of the coherent transmission groups at a time.

[0113] 8 shows an example of antenna switching for SRS transmissions for a 4T8R PNC WTRU in which both coherent transmission groups may be used. For example, different pairs of coherent Tx chains may be used for different (e.g., every) SRS transmissions. For example, the WTRU may use a first pair of coherent Tx chains of a first coherent transmission group for a first SRS transmission (e.g., an event) 81 and a second pair of coherent Tx chains of a second coherent transmission group for a second SRS transmission (e.g., an event) 82. For example, the WTRU may use a third pair of coherent Tx chains of the first coherent transmission group for a third SRS transmission (e.g., an event) 83 and a fourth pair of coherent Tx chains of the second coherent transmission group for a fourth SRS transmission (e.g., an event) 84.

[0114] Since (e.g., both) pairs of coherent Tx chains may be used (e.g., for consecutive SRS transmissions), the first and second SRS transmissions (e.g., events) 81, 82 may be consecutive, e.g., without being separated by a guard time. Similarly, the third and fourth SRS transmissions (e.g., events) 83, 84 may be consecutive, e.g., without being separated by a guard time. According to an embodiment, one instance (e.g., only) of antenna switching may be used, where, for example, four Tx chains may be switched from a first set of four antennas to a second set. According to an embodiment, a guard time may be used (e.g., only) to separate the second 82 and third 83 SRS transmissions (e.g., events), e.g., for antenna switching.

[0115] For example, the WTRU may select first and second coherent transmission groups, where the dimension of the SRS transmission may be, for example, x_coh=2.

[0116] For example, using the first selected coherent transmission group, the WTRU may transmit an SRS using, for example, two of the SRS resources of the configured SRS resource set for the first 81 and third 83 SRS transmissions (e.g., events).

[0117] For example, using the second selected coherent transmission group, the WTRU may transmit an SRS using, for example, two of the SRS resources of the configured SRS resource set for the second 82 and fourth 82 SRS transmissions (e.g., events).

[0118] For example, the WTRU may separate the second 82 and third 83 SRS transmissions (eg, events) by applying a guard time, eg, to allow for antenna switching.

[0119] 9 illustrates an example of antenna switching for SRS transmissions for a 4T8R NC WTRU in which four coherent transmission groups may be used. According to an embodiment, the WTRU may be an NC WTRU. In an NC WTRU, a single Tx chain (e.g., only one) may be considered a coherent transmission group for use during an SRS transmission (e.g., an event). In the illustrated example, a single Tx chain may be used for (e.g., each) transmission. For example, the WTRU may sequentially perform, e.g., the first 91, second 92, third 93, and fourth 94 SRS transmissions without any guard time between the SRS transmissions. For example, the WTRU may sequentially perform, e.g., the fifth 95, sixth 96, seventh 97, and eighth 98 SRS transmissions without any guard time between the SRS transmissions. In the illustrated example, one instance (e.g., only) of antenna switching may be used, where, for example, (e.g., all) four Tx chains may be switched from a first set of four antennas to a second set. According to an embodiment, a guard time may be used (e.g., only) to separate the fourth 94 and fifth 95 SRS transmissions, for example, due to antenna switching.

[0120] For example, the WTRU may select the first, second, third, and fourth coherent transmission groups, where the dimension of the SRS transmission may be, for example, x_coh=1.

[0121] For example, using the first selected coherent transmission group, the WTRU may transmit an SRS using, for example, one of the SRS resources of the configured SRS resource set for the first 91 and fifth 95 SRS transmissions (e.g., events).

[0122] For example, using the second selected coherent transmission group, the WTRU may transmit an SRS using, for example, one of the SRS resources of the configured SRS resource set for the second 92 and sixth 96 SRS transmissions (e.g., events).

[0123] For example, using the third selected coherent transmission group, the WTRU may transmit an SRS using, for example, one of the SRS resources of the configured SRS resource set for the third 93 and seventh 97 SRS transmissions (e.g., events).

[0124] For example, using the fourth selected coherent transmission group, the WTRU may transmit an SRS using, for example, one of the SRS resources of the configured SRS resource set for the fourth 94 and eighth 98 SRS transmissions (e.g., events).

[0125] For example, the WTRU may separate the fourth 94 and fifth 95 SRS transmissions (eg, events) by applying a guard time to allow for, eg, antenna switching.

[0126] 10 illustrates an example of antenna switching for SRS transmissions for a 4T8R PNC WTRU in which both coherent transmission groups may be used. According to an embodiment, the WTRU may use different pairs of coherent Tx chains for (e.g., every) SRS transmission (e.g., event). For example, the WTRU may perform a first 1001, a second 1002, a third 1003, and a fourth 1004 SRS transmission sequentially, e.g., without any guard time between the SRS transmissions. Considering that both pairs of coherent Tx chains may be used, the first 1001 and second 1002 SRS transmissions may be performed, e.g., without any guard time separating the first 1001 and second 1002 SRS transmissions. Similarly, the third 1003 and fourth 1004 SRS transmissions may be performed sequentially, e.g., without any guard time separating the third 1003 and fourth 1004 SRS transmissions. In the example shown in Figure 10, two instances of antenna switching may be used. For example, (e.g., each) instance may switch two Tx chains of a coherent transmission group, e.g., from a first set of two antennas to a second set. For example, the WTRU may switch antennas for the first coherent transmission group while a second SRS transmission using the second coherent transmission group may be in progress. In this way, a guard time may not be inserted between the second 1002 and third 1003 SRS transmissions (e.g., events).

[0127] For example, the WTRU may select first and second coherent transmission groups, where the dimension of the SRS transmission may be, for example, x_coh=2.

[0128] For example, using the first selected coherent transmission group, the WTRU may transmit an SRS using, for example, two of the SRS resources of the configured SRS resource set for the first 1001 and third 1003 SRS transmissions (e.g., events).

[0129] For example, using the second selected coherent transmission group, the WTRU may transmit an SRS using, for example, two of the SRS resources of the configured SRS resource set for the second 1002 and fourth SRS transmissions (e.g., events).

[0130] For example, the WTRU may switch antennas for a first coherent transmission group while a second SRS transmission using a second coherent transmission group may be in progress.

[0131] SRS Antenna Switching Example Using a Subset of Tx Chains According to an embodiment, the WTRU may not use (e.g., the entire set) of available Tx chains for SRS transmission at one time, and the WTRU may use (e.g., only) a subset of available Tx chains for SRS transmission at one time.

[0132] According to an embodiment, the WTRU may perform antenna switching for one subset of Tx chains while the WTRU may have (e.g., perform) ongoing transmissions on another subset of Tx chains.

[0133] The embodiments described herein may enable leveraging the coherence capabilities of a WTRU to improve downlink CSI estimation, for example.

[0134] The embodiments described herein may also allow for simplifying antenna switch circuitry in the WTRU, for example, by avoiding the use of (e.g., customized) switches, for example, a 3 to 1. The embodiments described herein may also allow for avoiding the use of cascaded switches, for example, two cascaded 2 to 1 switches, which may introduce insertion loss into the Tx chain.

[0135] The embodiments described herein may be applicable to FPNC WTRUs, for example, when WTRU coherency capabilities may not be considered for antenna switching. In other words, the switching mechanisms described in Figures 7-10 may be applicable when the WTRU is an FPNC WTRU or when WTRU coherency is not considered for SRS switching mechanism decisions. Figures 11-14 show antenna switching mechanisms based on embodiments described herein for a 4T6R WTRU.

[0136] 11 illustrates an example of SRS antenna port mapping for a 4T6R WTRU using one of a subset of Tx chains. In the illustrated example, the selected subset of Tx chains may be one of a pair of Tx chains. Using the selected subset of Tx chains, the WTRU may transmit SRS using, for example, two of the SRS resources of the SRS resource set configured in (e.g., each) transmission (e.g., event) 1111, 1112, 1113. In the illustrated example, for (e.g., each) transmission (e.g., event) 1111, 1112, 1113, a different pair of antenna ports may be used (e.g., connected to a pair of coherent Tx chains, e.g., (0, 1), (4, 5), (2, 3)). According to an embodiment, the WTRU may separate SRS transmissions (e.g., events) by applying guard times, for example, to allow for antenna switching.

[0137] 12 illustrates an example of SRS antenna port mapping for a 4T6R WTRU using both subsets of Tx chains. For example, different subsets of Tx chains may be used for different SRS transmissions. For example, the WTRU may use a first pair of Tx chains of a first subset for a first SRS transmission (e.g., event) 1211 and a second pair of Tx chains of a second subset for a second SRS transmission (e.g., event) 1212. For example, the WTRU may use a third pair of Tx chains of the first subset for a third SRS transmission (e.g., event) 1213. According to an embodiment, a guard time may be used to separate (e.g., only) the second 1212 and third 1213 SRS transmissions (e.g., events), e.g., for antenna switching.

[0138] 13 shows an example of SRS antenna port mapping for a 4T6R WTRU using (e.g., all, different) subsets of Tx chains. In the example shown, there may be four subsets of Tx chains (e.g., a single Tx chain).

[0139] 14 illustrates another example of SRS antenna port mapping for a 4T6R WTRU using (e.g., all, different) subsets of Tx chains. In the illustrated example, there may be two subsets of Tx chains, where a subset may include a pair of Tx chains.

[0140] Example of SRS antenna switching procedure for 2T6(8)R, 4T6(8)] Based on the principles described in the previous section, different embodiments of antenna switching in a 2 / 4T6(8)R WTRU are described herein. The same principles may be applicable to other xTyR WTRU dimensions.

[0141] In a 2T6R example, a WTRU may be configured with (e.g., receive configuration information indicating) two or more SRS resource sets, where (e.g., each) SRS resource set may have (e.g., include) six SRS resources transmitted in different symbols, and the SRS resources in (e.g., each) given set may include a single SRS port. For example, the SRS port of the first, third, and fifth SRS resources may be associated with a first WTRU antenna port, and the SRS port of the second, fourth, and sixth SRS resources may be associated with a second WTRU antenna port. For example, the WTRU may transmit the SRS resources sequentially, e.g., without (e.g., without) any guard symbols (e.g., time) between the transmission of the SRS resources, e.g., Y=0.

[0142] In a 4T6R example, a WTRU may be configured with (e.g., receive configuration information indicating) two or more SRS resource sets, where (e.g., each) SRS resource set may have (e.g., include) three SRS resources transmitted in different symbols, and the SRS resources in (e.g., each) given set may include two SRS ports (e.g., SRS port pairs). For example, the SRS port pair of the first and third SRS resources may be associated with a first WTRU antenna port pair, and the SRS port pair of the second SRS resource may be associated with a second WTRU antenna port pair. For example, the WTRU may transmit the SRS resources sequentially, e.g., without (e.g., without) any guard symbols (e.g., time) between the transmission of the SRS resources, e.g., Y=0.

[0143] In a 2T8R example, a WTRU may be configured with (e.g., receive configuration information indicating) two or more SRS resource sets, where (e.g., each) SRS resource set may have (e.g., include) eight SRS resources transmitted in different symbols, and the SRS resources in (e.g., each) given set may include a single SRS port. For example, the SRS port of the first, third, fifth, and seventh SRS resources may be associated with a first WTRU antenna port, and the SRS port pair of the second, fourth, sixth, and eighth SRS resources may be associated with a second WTRU antenna port. For example, the WTRU may transmit the SRS resources sequentially, e.g., without (e.g., without) any guard symbols (e.g., time) between the transmission of the SRS resources, e.g., Y=0.

[0144] In a 4T8R example, a WTRU may be configured with (e.g., receive configuration information indicating) two or more SRS resource sets, where (e.g., each) SRS resource set may have (e.g., include) four SRS resources transmitted in different symbols, and the SRS resources in (e.g., each) given set may include two SRS ports (e.g., SRS port pairs). For example, the SRS port pair of the first and third SRS resources may be associated with a first WTRU antenna port pair, and the SRS port pair of the second and fourth SRS resources may be associated with a second WTRU antenna port pair. For example, the WTRU may transmit the SRS resources sequentially, e.g., without (e.g., without) any guard symbols (e.g., time) between the transmission of the SRS resources, e.g., Y=0.

[0145] For example, a WTRU may indicate (e.g., transmit capability information indicating) its capability to perform antenna switching for a first subset of Tx chains when (e.g., during) it may have an ongoing transmission on a second subset of Tx chains. For example, if a WTRU declares (e.g., transmits capability information indicating) its capability for the antenna switching mechanism described above, the WTRU may receive a configuration (e.g., configuration information indicating) to perform antenna switching assuming (e.g., with) Y=0, where Y may be the number of guard symbols between the transmission of two SRS resources.

[0146] For example, if a WTRU declares its capability for the antenna switching mechanism described above (e.g., transmits capability information indicating same), the WTRU may determine from other configuration parameters (e.g., SRS configuration) whether it can assume Y=0 (e.g., no guard symbols between the transmission of two SRS resources). For example, if the number of symbols per SRS resource is such that the duration of an SRS transmission can extend beyond a predefined time boundary, e.g., a slot, the WTRU may assume an operating mode as described with Y=0 (e.g., may decide to transmit SRS resources sequentially without guard symbols (e.g., time) between transmitted SRS resources) in order to shorten the duration of channel sounding.

[0147] 16A-16C show examples of the above-described capabilities that may be used for SRS antenna switching in a 4T6R WTRU. As shown in FIG. 16A-16C, an SRS resource set may include three SRS resources (e.g., associated with two SRS ports) supporting two SRS ports (e.g., each). As shown in FIG. 16A, the WTRU may transmit a first SRS resource 1600 using a first pair of Tx chains 1602 and 1604 from a first antenna pair (0, 1). For example, as shown in FIG. 16B, the WTRU may transmit (e.g., proceed immediately to transmit) a second SRS resource 1610 using a second pair of Tx chains 1612 and 1614 from a second antenna pair (2, 3) (e.g., without any guard time between the first and second SRS resource transmissions). The WTRU may have an ongoing transmission from (e.g., using) its second Tx chain from the second antenna pair (2, 3), but the WTRU may switch its first pair of Tx chains 1602 and 1604 from the first antenna pair (0, 1) to the third antenna pair (4, 5). As shown in FIG. 16C, once the transmission of the second SRS resource is complete, the WTRU may (e.g., immediately) begin transmitting the third SRS resource 1620 from the third antenna pair (4, 5) (e.g., without waiting for any guard time after the completion of the transmission of the second SRS resource).

[0148] Example of gain compensation for unbalanced switching networks In some xTyR WTRU architectures, the antenna switching mechanism in the WTRU may not be balanced, resulting in different powers for transmitted SRS resources. For example, SRS transmissions by (e.g., from) some of the antenna ports may suffer some additional loss and may be x dB lower than their configured nominal power. Throughout the embodiments described herein, the term “x dB” may be used to refer to loss and may be meant as a variable. The parameter “x” used with “dB” may not be the same as the parameter “x” used in the descriptions of the xTyR configurations. For example, channel sounding based on SRS resources transmitted from those antenna ports may be lower power than other ports, resulting in potential distortion on the estimated downlink channel by the gNB. While the embodiments presented herein below are discussed using the case of SRS antenna switching, they may also be applicable to compensate for similar cases of power imbalance in other transmission scenarios.

[0149] Example of WTRU-assisted gNB-based compensation In one embodiment, the WTRU may indicate (e.g., transmit information indicative thereof) the existence of a power imbalance to the gNB, e.g., for compensation of an estimated channel at the gNB. For example, the WTRU may indicate (e.g., transmit information indicative thereof) the power imbalance by, e.g., indicating SRS resources that may be transmitted at a power different from the nominal power.

[0150] For example, the WTRU may indicate (e.g., transmit information to indicate) the existence of a power imbalance for SRS antenna switching. The indication (e.g., information) may also include the affected xTyR configuration. Furthermore, the indication (e.g., information) may be per BWP and / or band. As part of its capability information, the WTRU may indicate (e.g., transmit) information related to the power imbalance (e.g., per band, BWP, cell, etc., affected xTyR configuration, affected SRS resources, etc.).

[0151] For example, (e.g., alternatively) after the WTRU indicates the existence of a power imbalance (e.g., transmits information indicative thereof), the WTRU may be pinged (e.g., receive a request) to report (e.g., transmit) its SRS power imbalance information (e.g., indicating any of the affected xTyR configurations, affected SRS resources, etc., per band, BWP, cell, etc.).

[0152] For one or more xTyR SRS configurations, the indication of power imbalance may be per SRS resource and indicate the SRS resources that may be affected by the power imbalance. For example, (e.g., each) SRS resource set may have a separate indication according to the number of SRS resources in the set.

[0153] Figure 17 shows an example of a power imbalance reporting indication for a 4T6R WTRU. For example, the WTRU may be configured with (e.g., receive configuration information indicating) L SRS resources 1710-1720, where L is an integer. For example, the WTRU may transmit (e.g., a first) SRS using the first SRS resource 1710 at nominal power and may transmit (e.g., a second) SRS using the second SRS resource 1720 at lower power, e.g., due to implementation losses. For example, the WTRU may indicate (e.g., transmit power imbalance information indicating) a power imbalance per SRS resource with L bits (e.g., a bit field), where 1 indicates an SRS resource affected by a power imbalance (e.g., lower power). In Figure 17, the number of SRS resources is three (L=3). In another example (not shown), the indication of SRS resources affected by power imbalance may be performed using log2(L) bits, where (e.g., each) state of the log2(L) bits may correspond to (e.g., a different) case.

[0154] For one or more xTyR SRS configurations, the WTRU may, for example, indicate (e.g., transmit power imbalance information to indicate) a single value for the power imbalance of (e.g., all, different) affected SRS resources. In another example, the WTRU may indicate (e.g., transmit power imbalance information to indicate) one value for each (e.g., affected) SRS resource. For example, the WTRU may report (e.g., transmit power imbalance information to report) a (e.g., exact) power imbalance (e.g., such as any value selected from a set of predefined (e.g., predetermined) values ​​such as x dB and [wxyz] dB).

[0155] 18 illustrates a first example method for WTRU-assisted SRS power imbalance compensation. For example, the WTRU may transmit power imbalance information to the gNB for compensation and correct channel configuration.

[0156] For example, in step 1810, configuration information may be received by the WTRU from the gNB, where the configuration information may indicate one or more SRS resource sets (e.g., for antenna switching). For example, the configuration information may indicate that (e.g., each) SRS resource set may be associated with at least one transmit / receive (xTyR) antenna configuration in a set of xTyR antenna configurations.

[0157] For example, in step 1820, the WTRU may transmit information indicating the existence of an SRS power imbalance for at least one xTyR antenna configuration in the set of xTyR antenna configurations.

[0158] For example, in step 1830, the WTRU may receive a request to report SRS power imbalance information (eg, a message including information indicating the request).

[0159] For example, in step 1840, the WTRU may transmit (e.g., report) power imbalance information for at least one of the one or more SRS resource sets indicating, for at least one SRS resource set, any of: (i) one or more affected SRS resources in the set (e.g., via a bitmap); (ii) a power imbalance value (for (e.g., each or all) affected SRS resources in the set); (iii) an associated xTyR; and (iv) an associated BW portion (BWP).

[0160] WTRU-based compensation example In some xTyR WTRU architectures, the antenna switching mechanism in the WTRU may not be balanced, resulting in different powers of the transmitted SRS resources. For example, SRS resources transmitted by some of the antenna ports may be x dB lower than their nominal power. In some implementations, to ensure uniform power transmission from (e.g., all different) antenna ports, the WTRU may scale down the power for transmission of other SRS resources that may not be affected by a power imbalance in (e.g., associated with) the antenna switching mechanism. In other words, the WTRU may transmit on SRS resources of an SRS resource set that includes one or more SRS resources affected by an SRS power imbalance, and the SRS transmit power is scaled down for other SRS resources of the SRS resource set other than the affected one or more SRS resources, e.g., to provide uniform power transmission among the SRS resources of the SRS resource set. For example, the WTRU may perform any of the following: i) The WTRU may estimate the total SRS transmit power, e.g., as defined by a power control process;

[0161]

number

[0162] (ii) The WTRU allocates, for example, equal power P i First, N SRS For example, the WTRU may divide the power evenly across the SRS antenna ports. i For example, the WTRU may maintain a power level of x dB on the SRS port not affected by the loss, e.g., (P i -x) dB. (iii) The WTRU may report (eg, send information indicating) the loss incurred for transmission. (iv) The WTRU CMAX dBm (P CMAX -N SRS x) dBm, where "N SRS x" is the number of SRS antenna ports (N SRS ) multiplied by the power reduction x per antenna port.

[0163] In additional or alternative implementations, the WTRU may indicate (e.g., transmit information indicative of) scaling to the gNB application to enable the gNB to take into account reduced transmit power by the WTRU. Alternatively or additionally, the WTRU may report (e.g., transmit information indicative of) the loss incurred per SRS resource and (e.g., also) indicate (e.g., transmit information indicative of) the number of affected SRS resources to the gNB. For example, the WTRU may calculate the total power loss due to scaling and report (e.g., transmit information indicative of the calculated total power) to the gNB. For example, the report (e.g., information) may be part of (e.g., included in) WTRU capability signaling (e.g., message). In another example, the report (e.g., information) may be included in a separate report (e.g., message) indicating a value related to the incurred loss. For example, N SRS In a WTRU where the transmission of one of the SRS resources may suffer x dB loss, the WTRU may do one of the following: (i) The WTRU may report (e.g., transmit information indicating) the number of SRS resources affected by the power loss. For example, the WTRU may also report (e.g., transmit information indicating) their index (e.g., an indication of the affected SRS resource). (ii) The WTRU may reduce its power due to the total losses incurred, e.g., N SRS × dB (e.g., may transmit information indicating this). (iii) The WTRU may report its incurred loss (e.g., send information indicating thereof) by reporting (e.g., sending) the power headroom (PH) in a PH report (PHR).

[0164] In additional or alternative implementations, the WTRU may include the power loss due to scaling in the calculation of power headroom (PH). For example, the WTRU may reduce PH according to the loss incurred (e.g., the total power loss due to scaling).

[0165] For example, Type 1 PH can be calculated (in dB) according to the following formula:

[0166]

number

[0167] For example, if the WTRU is configured to CMAX For example, (P CMAX -N SRS x) dBm, the PH calculated using the above formula is (-N SRS x) dB. CMAX (P CMAX -N SRS x) dBm, the WTRU may calculate PH using the above formula.

[0168] In yet another example, the WTRU may indicate (e.g., transmit capability information indicating) its capability for power scaling of SRS resources that may not be affected by an imbalance in the antenna switching mechanism. For example, after the WTRU indicates its capability, the WTRU may receive configuration information indicating whether to apply power scaling.

[0169] In the embodiments described herein, the (e.g., maximum) power (e.g., WTRU configured maximum output power) is herein referred to as P CMAX For example, P CMAX may be determined for any of a cell, a frequency, a band, a cell group, and a BWP. CMAX may be determined for the WTRU as a whole. For example, P CMAXmay be determined by the WTRU or a MAC entity (eg, of the WTRU).

[0170] For example, the WTRU may determine a P based on the WTRU power class maximum power and one or more reductions or allowed reductions such as a spectral emission maximum power reduction (MPR), an additional MPR (A-MPR), and a power management MPR (P-MPR). CMAX The value of may be determined.

[0171] For example, the WTRU may determine P based on antenna imbalance, which may be determined by the WTRU. CMAX This reduction may be referred to herein as deltaAI.

[0172] For example, power headroom (PH) can be calculated using the power calculations described herein and CMAX The WTRU may determine the power from a power calculation by the WTRU, such as a value. CMAX -P, where P may be the calculated power. For example, delta AI may be determined as P CMAX For example, delta AI may be included in the calculation of P.

[0173] For example, the WTRU may send a PH report (e.g., to either the cell or the gNB) based on one or more triggers (e.g., conditions, events), which may include any of a path loss change (e.g., greater than a threshold), a timer expiration, a P-MPR or MPE change (e.g., greater than a threshold), and an SCell addition, etc.

[0174] When the WTRU sends a PH report (PHR), the PHR includes a PH value, P CMAX values ​​(e.g., P used to determine pH CMAXvalue), an indication of whether the PH is real or virtual, and whether the P-MPR is (e.g., P CMAX value), P CMAX For example, the PHR may include (e.g., for each of one or more cells) an indication of whether deltaAI has been applied to the PH value and the P-MPR value. CMAX It may (eg, also) include an indication of whether it has been applied (eg, used) in any calculation (eg, determination) of a value.

[0175] The deltaAI value is the power, PH, and P CMAX If any of the power, PH, and P is determined to be applicable, the WTRU may include any of the delta AI and instructions regarding applying the delta AI in the PHR. CMAX In any of the calculations (e.g., determinations), the instructions may indicate that deltaAI may be applied. For example, the instructions may indicate any value of deltaAI and a range of deltaAI values ​​that the deltaAI value may fall within. For example, the instructions may indicate to which antenna or antenna port deltaAI should be applied.

[0176] For example, the value of deltaAI (which may be in dB) is N SRS It may be equal to or calculated (eg, determined) as described for x.

[0177] Example of WTRU-based Tx dimension selection According to embodiments, any number of coherent transmission groups may be used, determined, and configured for SRS transmission. The number of coherent groups may be referred to herein as Nc. For example, a coherent transmission group may be any set of SRS antenna ports (e.g., Tx chains) that may be transmitting any of the same uplink symbols at the same time. For example, a WTRU may transmit in Nc SRS transmission opportunities, and a coherent transmission group may be used in (e.g., each) SRS transmission opportunity.

[0178] For example, a coherent transmission group may include SRS antenna ports (eg, Tx chains) that may be coherent (eg, with respect to each other).

[0179] For example, (eg, each) coherent transmission group may have (eg, associated with) an identifier (eg, index), such as, for example, 1, 1, . . . , Nc-1.

[0180] For example, (eg, each) coherent transmission group may have the same number of SRS antenna ports (eg, Tx chains).

[0181] According to an embodiment, a WTRU may be configured with a number of SRS transmission opportunities (sometimes referred to herein as Ns) having Nc coherent groups. For example, the number Ns of SRS transmission opportunities may be configured and determined within a time window. For example, the time window may be periodic (e.g., occurring periodically), aperiodic, and semi-persistent.

[0182] According to the embodiment, any of the following may be applicable:

[0183] If the number of transmission opportunities (Ns) is the same as the number of coherent transmission groups (Nc), e.g., if Ns=Nc, the WTRU may use the coherent groups for transmission in (e.g., each) transmission opportunity, e.g., in a non-overlapping manner.

[0184] When the number of transmission opportunities (Ns) is the same as the number of coherent transmission groups (Nc), for example, when Ns = Nc, the coherent transmission group index (e.g., identifier) can be determined based on, for example, the number of SRS transmission opportunities. For example, a coherent transmission group having a first coherent group index can be used for transmission at the first SRS opportunity within a time window, another coherent group having a second coherent group index can be used for transmission at the second SRS opportunity within the time window, and so on.

[0185] When the number of transmission opportunities (Ns) is less than the number of coherent transmission groups (Nc), for example, when Ns < Nc, the WTRU can determine a subset of the coherent transmission groups for SRS transmission based on any of DL measurements, (e.g., dynamic) indications, and maximum permitted exposure (MPE) related parameters.

[0186] In a DL measurement example, a WTRU may acquire (e.g., measure) downlink signal quality through an Rx antenna associated with (e.g., each) coherent transmission group, and the WTRU may obtain (e.g., determine) a subset of coherent transmission groups based on the (e.g., measured) downlink signal quality. For example, the WTRU may acquire (e.g., determine, select) a subset of coherent transmission groups that may have the highest downlink signal quality. In another example, the WTRU may acquire (e.g., determine, select) a subset of coherent transmission groups that may have a downlink signal quality above a certain value. The downlink (e.g., measured) signal quality may be any of reference signal received power (RSRP), L1-RSRP, Layer-1 signal to interference and noise ratio (L1-SINR), and path loss (PL) signal quality. Any technique for acquiring downlink signal quality and selecting any number of subsets of coherent transmission groups based on the downlink signal quality may be applicable to the embodiments described herein.

[0187] In an example of (e.g., dynamic) indication, when a gNB triggers an SRS transmission (e.g., either aperiodic or semi-persistent SRS transmission), the associated DL control channel may indicate which subset of the coherent transmission group may be used for transmission in (e.g., any configured and indicated) SRS transmission opportunity.

[0188] In an example of an MPE-related parameter, the WTRU may obtain (e.g., determine, select) a subset of coherent transmission groups based on the MPE-related parameter (e.g., a coherent transmission group subset having a less power backoff than another may be selected).

[0189] When the number of transmission opportunities (Ns) is less than the number of coherent transmission groups (Nc), for example, when Ns < Nc, the WTRU may use Ns coherent groups for transmission in the Ns SRS transmission opportunities. The Ns coherent groups may be obtained (e.g., determined) using the coherent group index in either ascending or descending order.

[0190] When the number of transmission opportunities (Ns) is less than the number of coherent transmission groups (Nc), for example, when Ns < Nc, the (e.g., obtained, determined, selected) coherent transmission groups may be indicated to the gNB based on any of the following examples.

[0191] In the first example, each coherent transmission group may be associated with SRS parameters, such as an SRS sequence, a comb index, and a pattern. The WTRU may use the coherent group obtained (e.g., determined) based on the associated SRS parameters for transmission. The gNB may (e.g., blindly) detect the determined (e.g., selected) coherent group based on the (e.g., used) SRS parameters.

[0192] In the second example, an (e.g., explicit) indication may be transmitted by the WTRU to indicate the (e.g., obtained, determined, selected) coherent transmission group, for example, via an uplink control channel (e.g., PUCCH).

[0193] According to an embodiment, the number of transmission opportunities (Ns) may be obtained (e.g., determined) based on any of the following examples.

[0194] In the first example, Ns may be obtained based on the xTyR antenna configuration. For example, the Ns value may be determined based on the combination of antenna dimensions (x, y). [[ID=二十二]]

[0195] In a second example, Ns may be obtained based on a (eg, predefined, preconfigured, fixed) number (eg, Ns=1).

[0196] In a third example, Ns may be indicated via associated downlink control information (DCI) (eg, triggering SRS transmission).

[0197] In a fourth example, Ns may be configured via higher layer signaling.

[0198] In a fifth example, NS may be obtained based on a codebook subset (or codebook) that may be configured for uplink transmission.

[0199] FIG. 15 illustrates an example method 1500 for SRS antenna switching.

[0200] According to an embodiment, the method may include performing SRS antenna switching in either a first mode of operation or a second mode of operation. For example, the WTRU may be pre-configured or dynamically configured with either the first or second mode of operation. For example, when the WTRU is operating (e.g., configured) in the first mode of operation, the SRS antenna switching may be performed according to the Tx dimension (e.g., number of Tx chains) and Rx dimension (e.g., number of Rx chains / antennas) of the WTRU.

[0201] In step 1510 (eg, optional), the WTRU may be configured to perform SRS antenna switching in the second mode of operation.

[0202] According to an embodiment, in step 1520, in the second mode of operation, SRS antenna switching may be performed according to the WTRU coherence capability and Rx dimension.

[0203] For example, in the second mode of operation, a subset of the available Tx chains may be used for SRS transmission at a time.

[0204] For example, SRS antenna switching may be performed in a second operating mode for a second subset of Tx chains during an ongoing transmission on a first subset of Tx chains.

[0205] For example, a first and a second subset of Tx chains may transmit, respectively, at first and second occasions that may occur successively, eg, without being separated by a guard time.

[0206] For example, the WTRU coherence capability may indicate whether the WTRU can be any of a non-coherent (NC) WTRU, a partially non-coherent (PNC) WTRU, and a full and partial non-coherent (FPNC) WTRU.

[0207] For example, either the NC and PNC WTRU coherence capabilities may further include a smaller number of coherent Tx chains than the Tx dimension.

[0208] For example, the method may further include transmitting an indication of the WTRU coherence capability, for example, for downlink channel estimation, by, for example, the gNB.

[0209] For example, for either the NC and PNC WTRU, the subset of Tx chains may include (eg, only) coherent Tx chains.

[0210] For example, for either the NC or PNC WTRU, a first subset of Tx chains may include (e.g., only) coherent Tx chains, and a second subset of Tx chains may include (e.g., only) coherent Tx chains.

[0211] For example, the WTRU may be an FPNC WTRU.

[0212] For example, a WTRU may be configured with two or more SRS resource sets, where (e.g., each) SRS resource set may have (e.g., include) two or more SRS resources transmitted in different symbols, and (e.g., each) SRS resource in a given set may include one or more SRS ports. For example, the WTRU may be configured to indicate (e.g., transmit information indicating) its capability to perform antenna switching for a first subset of Tx chains to the gNB when (e.g., during) it may have an ongoing transmission on a second subset of Tx chains. For example, the gNB may be configured to at least one of assume that Y=0 or query the WTRU whether Y=0, where Y may be the number of guard symbols between SRS resource transmissions.

[0213] For example, the WTRU may be configured to indicate (e.g., transmit information indicative of) a power imbalance for compensation of an estimated channel at the gNB to the gNB.

[0214] For example, the WTRU may be configured to scale down the transmit power of one or more SRS resources to eliminate power differences between two or more SRS resources, thereby ensuring uniform power transmission.

[0215] For example, the WTRU may be configured to at least one of (i) indicate its application of power scaling to the gNB and (ii) indicate its ability to perform scaling to the gNB, and the WTRU may be configured to perform the scaling in response to a configuration received from the gNB.

[0216] 19 illustrates an example method 1900 for WTRU-assisted SRS power imbalance compensation. According to an embodiment, the method 1900 may be implemented in a WTRU and may include, for example, transmitting 1920 information indicating the existence of an SRS power imbalance for at least one transmit and receive (e.g., xTyR) antenna configuration within a set of (e.g., xTyR) antenna configurations (e.g., for SRS antenna switching). For example, the method 1900 may further include receiving 1930 a request to report (e.g., a message comprising information indicative thereof) the SRS power imbalance information. For example, the method 1900 may further include, for at least one SRS resource set associated with the at least one (e.g., xTyR) antenna configuration (e.g., for SRS antenna switching), transmitting 1940 SRS power imbalance information indicating (i) one or more affected SRS resources within the at least one SRS resource set and (ii) one or more power imbalance values ​​for the one or more affected SRS resources.

[0217] For example, the SRS power imbalance information may further indicate at least one (eg, xTyR) antenna configuration (eg, for SRS antenna switching) that may be associated with the at least one SRS resource set.

[0218] For example, the SRS power imbalance information may further indicate a bandwidth part (BWP) that may be associated with at least one SRS resource set.

[0219] For example, the indicated presence of SRS power imbalance information may indicate that an SRS transmitted in one or more affected SRS resources may be transmitted at a power lower than the nominal power.

[0220] For example, method 1900 may include receiving configuration information indicating at least one SRS resource set associated with at least one (e.g., xTyR) antenna configuration (e.g., for SRS antenna switching) (e.g., before transmitting information indicating the existence of an SRS power imbalance).

[0221] For example, the SRS power imbalance information may include a bitmap that may indicate one or more affected SRS resources in at least one SRS resource set.

[0222] For example, the one or more power imbalance values ​​for one or more affected SRS resources may include a value for (e.g., each) affected SRS resource. For example, the one or more power imbalance values ​​may include different values ​​for different affected SRS resources.

[0223] For example, the one or more power imbalance values ​​may include values ​​for (eg, all different) affected SRS resources.

[0224] For example, the one or more power imbalance values ​​may correspond to one or more values ​​selected from a predetermined set of values.

[0225] For example, at least one xTyR antenna configuration may include a coherent group of transmit (Tx) chains that may be associated with a subset of SRS resources of at least one SRS resource set.

[0226] For example, the method 1900 may further include transmitting at least one SRS in the subset of SRS resources using a coherent group of Tx chains associated with the subset of SRS resources.

[0227] For example, the method 1900 may further include transmitting coherence (eg, capability) information indicating a number of coherent groups of transmit (Tx) chains, eg, for the set of xTyR antenna configurations.

[0228] For example, the coherence (eg, capability) information may further indicate whether the WTRU is non-coherent (NC), partially non-coherent (PNC), or fully partial non-coherent (FPNC).

[0229] For example, the coherence capability information may further indicate, for example, the number of coherent groups of transmit (Tx) chains for a set of xTyR antenna configurations.

[0230] For example, the method 1900 may further include associating the coherent group of Tx chains with a subset of SRS resources of the at least one SRS resource set.

[0231] For example, the method 1900 may further include transmitting the subset of SRS resources using a coherent group associated with the subset of SRS resources.

[0232] For example, at least one SRS resource set may include three SRS resources, where (eg, each) SRS resource includes two SRS ports.

[0233] For example, the method 1900 may further include sequentially transmitting the first, second, and third SRSs in the first, second, and third SRS resources of the at least one SRS resource set from first, second, and third pairs of antenna ports, respectively, according to at least one xTyR antenna configuration associated with the at least one SRS resource set.

[0234] For example, the first SRS and the third SRS may be transmitted using a first pair of Tx chains, and the second SRS may be transmitted using a second pair of Tx chains.

[0235] For example, the first pair of Tx chains may be switched from the third pair of antenna ports to the first pair of antenna ports while the second SRS is transmitted using the second pair of Tx chains from the second pair of antenna ports.

[0236] For example, the first SRS and the second SRS may be transmitted sequentially, eg, without any guard time between them.

[0237] For example, the second SRS and the third SRS may be transmitted sequentially, eg, without any guard time between them.

[0238] For example, the method 1900 may further include transmitting capability information indicating an ability to perform antenna switching for the first pair of Tx chains during an ongoing SRS transmission on the second pair of Tx chains.

[0239] 20 illustrates an example method 2000 for WTRU-based SRS power imbalance compensation. According to an embodiment, method 2000 may be implemented in a WTRU and may include transmitting 2020 on SRS resources of an SRS resource set, where the SRS resource set may include one or more SRS resources affected by an SRS power imbalance, and SRS transmit power may be scaled down for other SRS resources of the SRS resource set other than the affected one or more SRS resources, e.g., to provide uniform power transmission among the SRS resources of the SRS resource set. For example, method 2000 may further include transmitting 2040 information indicating that the SRS transmit power may be scaled down for the SRS resource set.

[0240] For example, transmissions in the affected one or more SRS resources may be transmitted at a power lower than the nominal power.

[0241] For example, the transmitted information may further indicate the power loss for (each of) the affected one or more SRS resources.

[0242] For example, the transmitted information may further indicate the number of one or more SRS resources affected.

[0243] For example, the transmitted information may further indicate one or more indexes (eg, identifiers) of the one or more affected SRS resources.

[0244] For example, the transmitted information may further indicate the total power loss due to the scaled SRS transmit power.

[0245] For example, the transmitted information indicating that the SRS transmit power has been scaled down may be included in the power headroom.

[0246] For example, the power headroom may be reduced according to the total power dissipation.

[0247] For example, the power headroom may be included in a power headroom report.

[0248] For example, the method 2000 may further include, before scaling down the SRS transmit power, transmitting capability information indicating a capability to scale down the SRS transmit power to provide uniform power transmission among the SRS resources of the SRS resource set.

[0249] For example, the method 2000 may further include receiving configuration information indicating scaling down SRS transmit power for other SRS resources of the SRS resource set other than the affected one or more SRS resources.

[0250] Although not explicitly stated, the embodiments described herein may be used in any combination or subcombination, for example, the principles described herein are not limited to the variations described, but rather any arrangement of variations and embodiments may be used.

[0251] Additionally, any features, variations, or embodiments described in the methods are compatible with an apparatus device including means for processing the disclosed methods, compatible with a device with a processor configured to process the disclosed methods, compatible with a computer program product including program code instructions, and compatible with a non-transitory computer-readable storage medium storing program instructions.

[0252] conclusion While features and elements are described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

[0253] Furthermore, in the above embodiments, processing platforms, computing systems, controllers, and other devices including processors are described. These devices may include at least one central processing unit ("CPU") and memory. In accordance with the practices of those skilled in the art of computer programming, references to acts and symbolic representations of operations or instructions may be performed by various CPUs and memories. Such acts and operations or instructions may be referred to as being "executed," "executed by a computer," or "executed by a CPU."

[0254] Those skilled in the art will understand that the operations and symbolically represented operations or instructions include the manipulation of electrical signals by a CPU. The electrical system represents data bits that can cause a resulting transformation or reduction of the electrical signals, and maintains the data bits in memory locations in a memory system, thereby reconfiguring or otherwise altering the operation of the CPU and the processing of other signals. The memory locations in which the data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties that correspond to or represent the data bits. It should be understood that exemplary embodiments are not limited to the platforms or CPUs described above, and that other platforms and CPUs may support the provided methods.

[0255] The data bits may also be maintained on computer-readable media, including magnetic disks, optical disks, and any other volatile (e.g., random access memory ("RAM")) or non-volatile (e.g., read-only memory ("ROM")) mass storage system readable by a CPU. The computer-readable media may include cooperative or interconnected computer-readable media that reside exclusively on a processing system or that are distributed among multiple interconnected processing systems, which may be local or remote to a processing system. Representative embodiments are not limited to the memories described above, and it will be understood that other platforms and memories may support the described methods.

[0256] In an exemplary embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium, which may be executed by a processor of a mobile, a network element, and / or any other computing device.

[0257] There is little distinction between hardware and software implementations of aspects of the system. The use of hardware or software is generally a design choice representing a cost vs. efficiency trade-off (e.g., in that the choice between hardware and software can be important in certain contexts, although not always). There may be a variety of vehicles (e.g., hardware, software, and / or firmware) in which the processes and / or systems and / or other techniques described herein may be effective, and the preferred vehicle may vary depending on the context in which the processes and / or systems and / or other techniques are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may select a primarily hardware and / or firmware vehicle. If flexibility is paramount, the implementer may select a primarily software implementation. Alternatively, the implementer may select some combination of hardware, software, and / or firmware.

[0258] The foregoing detailed description has illustrated various embodiments of devices and / or processes through the use of block diagrams, flowcharts, and / or examples. To the extent that such block diagrams, flowcharts, and / or examples include one or more functions and / or operations, those skilled in the art will appreciate that each function and / or operation in such block diagrams, flowcharts, or examples may be individually and / or collectively implemented by a wide variety of hardware, software, firmware, or substantially any combination thereof. Suitable processors include, by way of example, a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), an application specific standard product (ASSP), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), and / or a state machine.

[0259] While features and elements are provided above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with other features and elements. The present disclosure is not limited in terms of the specific embodiments described herein; these embodiments are intended as illustrations of various aspects. It will be apparent to those skilled in the art that many modifications and variations can be made without departing from the spirit and scope of the present invention. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly stated as such. Functionally equivalent methods and apparatuses within the scope of the present disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing specification. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is understood that the present disclosure is not limited to any particular method or system.

[0260] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, and when referred to herein, the terms "station" and its abbreviation "STA," "user equipment" and its abbreviation "UE" may mean (i) a wireless transmit and / or receive unit (WTRU), such as a described infrastructure; (ii) any of several embodiments of a WTRU, such as a described infrastructure; (iii) a wireless-enabled and / or wired (e.g., tethered) device configured with some or all of the structure and functionality of a WTRU, such as a described infrastructure, among others; (iii) a wireless-enabled and / or wired device configured with less than all of the structure and functionality of a WTRU, such as a described infrastructure; or (iv) the like. Details of an exemplary WTRU that may represent any of the UEs enumerated herein are provided below with respect to FIGS. 1A-1D.

[0261] In certain exemplary embodiments, portions of the subject matter described herein may be implemented via application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), and / or other integrated formats. However, those skilled in the art will recognize that certain aspects of the embodiments disclosed herein may be equivalently implemented in whole or in part in an integrated circuit as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as substantially any combination thereof, and that designing circuitry and / or writing software and / or firmware code is within the skill of those skilled in the art in light of this disclosure. Additionally, those skilled in the art will understand that the mechanisms of the subject matter described herein may be distributed as program products in various forms, and that the exemplary embodiments of the subject matter described herein apply regardless of the particular type of signal-bearing medium used to actually effect the distribution. Examples of signal bearing media include, but are not limited to, recordable media such as floppy disks, hard disk drives, CDs, DVDs, digital tape, computer memory, and transmission media such as digital and / or analog communications media (e.g., fiber optic cables, wave guides, wired communications links, wireless communications links, etc.).

[0262] The subject matter described herein may, in some cases, depict different components that are contained within or connected to different other components. It should be understood that such illustrated architectures are merely examples, and that in fact many other architectures that achieve the same functionality may be implemented. Conceptually, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality may be achieved. Thus, any two components combined herein to achieve a particular function can be viewed as “associated” with each other such that the desired functionality is achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated can also be considered to be “operably connected” or “operably coupled” to each other to achieve the desired functionality, and any two components so associated can also be considered to be “operably coupleable” to each other to achieve the desired functionality. Examples of operably coupleable include, but are not limited to, components that are physically matable and / or physically interacting, and / or components that are wirelessly interacting and / or wirelessly interacting, and / or components that logically interact and / or logically interacting.

[0263] With respect to the use of virtually any plural and / or singular term herein, those skilled in the art can convert from plural to singular and / or from singular to plural as appropriate to the context and / or application. Various singular / plural permutations may be expressly set forth herein for purposes of clarity.

[0264] In general, those skilled in the art will understand that the terms used in this specification, and particularly in the appended claims (e.g., the body of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," and the term "comprises" should be interpreted as "including, but not limited to"). Those skilled in the art will further understand that where a specific number of recitations of an introduced claim are intended, such intention will be explicitly set forth in the claim; in the absence of such recitation, no such intention exists. For example, where only one item is intended, the term "single" or similar language may be used. To assist in understanding, the following appended claims and / or description of this specification may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed as meaning that the introduction of a claim recitation with the indefinite article "a" or "an" limits any particular claim containing such an introduced claim recitation to embodiments containing only one such recitation, even if the same claim contains the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be interpreted to mean "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim recitations. Additionally, those skilled in the art will recognize that even when a specific number of introduced claim recitations is explicitly recited, such recitation should be interpreted to mean at least the recited number (e.g., the simple recitation "two recitations" without other modifiers means at least two recitations, or more than two recitations).

[0265] Furthermore, when notation similar to "at least one of A, B, and C" is used, such structure is generally intended as the meaning that one of ordinary skill in the art would understand the notation (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, a system having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together). When notation similar to "at least one of A, B, or C" is used, such structure is generally intended as the meaning that one of ordinary skill in the art would understand the notation (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, a system having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together). Those skilled in the art will further appreciate that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the specification, claims, or drawings, should be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" should be understood to include the possibilities of "A" or "B" or "A and B." Furthermore, as used herein, the term "any of," followed by a list of items and / or a list of categories of items, is intended to include "any of," "any combination of," "any plurality of," and / or "any combination of" of the items and / or categories of items, individually or in combination with other items and / or other categories of items. Furthermore, as used herein, the terms "set" or "group" are intended to include any number of items, including zero. Additionally, as used herein, the term "number" is intended to include any number, including zero.

[0266] Additionally, where features or aspects of the disclosure are described in terms of a Markush group, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0267] As will be understood by those skilled in the art, for all purposes, including in terms of providing a written description, all ranges disclosed herein encompass any possible subranges and combinations of subranges. Any recited range can be readily recognized as fully descriptive and allowing the same range to be broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be easily broken down into a lower third, middle third, upper third, etc. As will also be understood by those skilled in the art, all terms such as "up to," "at least," "greater than," "less than," etc., refer to ranges that are inclusive of the recited number and that can be further broken down into subranges as discussed above. Finally, as will be understood by those skilled in the art, ranges include each individual element. Thus, for example, a group having 1 to 3 cells refers to a group having 1, 2, or 3 cells. Similarly, a group having 1 to 5 cells refers to a group having 1, 2, 3, 4, or 5 cells, and so on.

[0268] Furthermore, the claims should not be read as limited to the provided order or to the provided elements unless specifically so stated. Additionally, the use of the term "means for" in any claim is intended to invoke 35 U.S.C. 112, paragraph 6, or means-plus-function claim format, and any claim without the term "means for" is not so intended.

[0269] Software and associated processors may be used to implement a radio frequency transceiver for use in a wireless transmit / receive unit (WTRU), user equipment (UE), terminal, base station, mobility management entity (MME), or evolved packet core (EPC), or any host computer. The WTRU may be used in conjunction with modules implemented in hardware and / or software, such as, for example, a software defined radio (SDR), and may also be implemented in other components, such as a camera, a video camera module, a video phone, a speaker phone, a vibration device, a speaker, a microphone, a television transceiver, a hands-free headset, a keyboard, a Bluetooth module, a frequency modulation (FM) radio unit, a near field communication (NFC) module, an LCD display unit, an organic light emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an internet browser, and / or a wireless local area network (WLAN) or ultra wide band (UWB) module.

[0270] Although the present invention has been described with respect to a communications system, it is contemplated that the system may be implemented in software on a microprocessor / general purpose computer (not shown). In particular embodiments, one or more of the functions of the various components may be implemented in software controlling a general purpose computer.

[0271] Additionally, although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications of the details can be made within the scope of the claims and equivalents thereof without departing from the invention.

[0272] Throughout this disclosure, those skilled in the art will understand that certain exemplary embodiments may be used alternatively or in combination with other exemplary embodiments.

Claims

1. 1. A method performed by a wireless transmit / receive unit (WTRU), comprising: transmitting information to a base station indicating the presence of a sounding reference signal (SRS) power imbalance for at least one transmit and receive (xTyR) antenna configuration in a set of xTyR antenna configurations; receiving a request to report SRS power imbalance information from the base station; transmitting, for at least one SRS resource set associated with the at least one xTyR antenna configuration, the SRS power imbalance information to the base station indicating (i) one or more affected SRS resources in the at least one SRS resource set, and (ii) one or more power imbalance values ​​for the one or more affected SRS resources; A method comprising:

2. The method described in claim 1, wherein the information indicating the existence of an SRS power imbalance indicates that the SRS transmitted in the one or more affected SRS resources is transmitted at a power lower than the nominal power.

3. The method of claim 1 or 2, wherein the SRS power imbalance information indicates the at least one xTyR antenna configuration associated with the at least one SRS resource set.

4. The method of claim 1 , wherein the SRS power imbalance information indicates a bandwidth portion associated with the at least one SRS resource set.

5. Receiving configuration information indicating the at least one SRS resource set associated with the at least one xTyR antenna configuration.

5. The method according to claim 1, comprising:

6. The method of claim 1 , wherein the SRS power imbalance information comprises a bitmap indicating the one or more affected SRS resources in the at least one SRS resource set.

7. The method of claim 1 , wherein the one or more power imbalance values ​​for the one or more affected SRS resources include a value for each affected SRS resource.

8. The method of claim 1 , wherein the one or more power imbalance values ​​include values ​​for all the affected SRS resources.

9. The method of claim 1 , wherein the one or more power imbalance values ​​correspond to one or more values ​​selected from a predetermined set of values.

10. The method according to claim 1 , wherein the at least one SRS resource set includes three SRS resources, each SRS resource including two SRS ports.

11. sequentially transmitting a first SRS, a second SRS, and a third SRS from first, second, and third pairs of antenna ports, respectively, in first, second, and third SRS resources of the at least one SRS resource set, according to the at least one xTyR antenna configuration associated with the at least one SRS resource set. The method of claim 10, comprising:

12. 12. The method of claim 11, wherein the first SRS and the third SRS are transmitted using a first pair of Tx chains, and the second SRS is transmitted using a second pair of Tx chains.

13. 13. The method of claim 12, wherein the first pair of Tx chains is switched from the third pair of antenna ports to the first pair of antenna ports while the second SRS is transmitted using the second pair of Tx chains from the second pair of antenna ports.

14. The method of claim 11 , wherein the first SRS, the second SRS, and the third SRS are transmitted sequentially without any guard time between them.

15. 1. A wireless transmit / receive unit (WTRU) comprising circuitry including any of a transmitter, a receiver, a processor, and a memory, transmitting information to a base station indicating the presence of a sounding reference signal (SRS) power imbalance for at least one transmit and receive (xTyR) antenna configuration in a set of xTyR antenna configurations; receiving a request from the base station to report SRS power imbalance information; For at least one SRS resource set associated with the at least one xTyR antenna configuration, transmit the SRS power imbalance information to the base station indicating (i) one or more affected SRS resources within the at least one SRS resource set, and (ii) one or more power imbalance values ​​for the one or more affected SRS resources. The WTRU is configured to:

16. A WTRU as described in claim 15, wherein the information indicating the existence of an SRS power imbalance indicates that the SRS transmitted in the one or more affected SRS resources is transmitted at a power lower than the nominal power.

17. A WTRU as described in claim 15 or 16, wherein the SRS power imbalance information indicates the at least one xTyR antenna configuration associated with the at least one SRS resource set.

18. A WTRU as claimed in any one of claims 15 to 17, wherein the SRS power imbalance information indicates a bandwidth portion associated with the at least one SRS resource set.

19. A WTRU as described in any one of claims 15 to 18, wherein the SRS power imbalance information includes a bitmap indicating the one or more affected SRS resources within the at least one SRS resource set.

20. A WTRU as claimed in any one of claims 15 to 19, wherein the one or more power imbalance values ​​include values ​​for all of the affected SRS resources.

Images