Enhanced CBSR with CSI feedback overhead reduction

Abstract

A method implemented by a wireless transmit / receive unit (WTRU) may include receiving a CSI resource configuration. The CSI resource configuration may include information related to a grid-of-beams (GoB) that includes a plurality of beams, an indication to partition the GoB into sub-grids, an indication of an initial set of candidate beams, and a selection criteria. One or more beams of the initial set of candidate beams may be determined for selection based on the selection criteria. A precoding matrix indicator (PMI) may be sent based on the one or more beams of the initial set of candidate beams that were selected.

Description

ENHANCED CBSR WITH CSI FEEDBACK OVERHEAD REDUCTIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 607,350, filed on December 7, 2023, entitled “Enhanced CBSR with CSI Feedback Overhead Reduction”, the contents of which is hereby incorporated by reference herein in its entirety.BACKGROUND

[0002] A wireless system with larger antenna arrays offers several benefits, including spatial multiplexing, diversity, and multi-user multiple-input-multiple-output (MU-MIMO). However, a larger number of antenna elements or antenna ports also cause increased interference to the neighboring cells / users, WTRU complexity and channel state information (CSI) feedback overhead. Support for an increased number of antenna ports at the gNB may be a target enhancement. The objective is to increase the number of antenna ports at the gNB to enhance the link quality. However, such enhancement comes at the expense of increased interference to the neighboring cells / user, WTRU complexity and feedback overhead.SUMMARY

[0003] A wireless receive / transmit unit (WTRU) may comprise a processor configured to receive a CSI resource configuration. The CSI resource configuration may include information related to a grid-of-beams (GoB) that includes a plurality of beams, an indication to partition the GoB into sub-grids, an indication of an initial set of candidate beams, and a selection criteria. One or more beams of the initial set of candidate beams may be determined for selection based on the selection criteria. A precoding matrix indicator (PMI) may be sent based on the one or more beams of the initial set of candidate beams that were selected.

[0004] The processor may be configured to send a CSI report message including information related to one or more beams of the initial set of candidate beams that were not selected.

[0005] The processor may be configured to select beams from the initial set of candidate beams based on amplitude levels or a window of amplitude levels for beams in one or more of the sub-grids of the GoB and a threshold amount.

[0006] The selection criteria may include one or more of a maximum amplitude level, a minimum amplitude level, or an amplitude level window.

[0007] The processor may be configured to receive a class indication. The class indication may include a first class indication that indicates that the one or more beams of the initial set of candidate beams areselected based on a maximum amplitude level, a minimum amplitude level, or an amplitude level window. The class indication may include a second class indication that indicates that processor should exclude one or more beams that are not part of the initial set of candidate beams. The processor may be configured to receive an indication of a reference amplitude for each of the one or more indicated sub-grids.

[0008] The processor may be configured to select one or more beams from the one or more indicated sub-grids based on the indicated reference amplitude for each of the one or more indicated sub-grids being greater than a threshold amount.

[0009] The processor may be configured to determine quantized values for one or more beams in the initial set of candidate beams, and to identify beams for selection based on a comparison of the quantized values for the one or more beams to the selection criteria.

[0010] The processor may be configured to determine a strongest beam from the plurality of beams in the GoB based on a comparison of amplitude levels for each of the plurality of beams, and to determine a relative amplitude level for each of the plurality of beams not determined to be the strongest beam using an amplitude level of the strongest beam as a scaling reference.

[0011] Methods implemented by a wireless transmit / receive unit (WTRU) may be described herein. The method may include receiving a CSI resource configuration. The CSI resource configuration may include information related to a grid-of-beams (GoB) that includes a plurality of beams, an indication to partition the GoB into sub-grids, an indication of an initial set of candidate beams, and a selection criteria. One or more beams of the initial set of candidate beams may be determined for selection based on the selection criteria. A precoding matrix indicator (PMI) may be sent based on the one or more beams of the initial set of candidate beams that were selected.

[0012] The method may include sending a CSI report message comprising information related to one or more beams of the initial set of candidate beams that were not selected.

[0013] The method may include selecting beams from the initial set of candidate beams based on amplitude levels or a window of amplitude levels for beams in one or more of the sub-grids of the GoB and a threshold amount.

[0014] The selection criteria may include one or more of a maximum amplitude level, a minimum amplitude level, or an amplitude level window.

[0015] The method may include receiving a class indication. The class indication may include a first class indication that indicates that the one or more beams of the initial set of candidate beams are selected based on a maximum amplitude level, a minimum amplitude level, or an amplitude level window. The classindication may include a second class indication that indicates that processor should exclude one or more beams that are not part of the initial set of candidate beams.

[0016] The method may include receiving an indication of a reference amplitude for each of the one or more indicated sub-grids.

[0017] The method may include selecting one or more beams from the one or more indicated sub-grids based on the reference amplitude for each of the one or more indicated sub-grids being greater than a threshold amount.

[0018] The method may include determining quantized values for one or more beams in the initial set of candidate beams, and identifying beams for selection based on a comparison of the quantized values for the one or more beams to the selection criteria.

[0019] The method may include determining a strongest beam from the plurality of beams in the GoB based on a comparison of amplitude levels for each of the plurality of beams, and determining a relative amplitude level for each of the plurality of beams not determined to be the strongest beam using an amplitude level of the strongest beam as a scaling reference.

[0020] The method may include selecting beams from the initial set of candidate beams based on the determined relative amplitude level for each of the plurality of beams of the GoB and a threshold amount.

[0021] A wireless receive / transmit unit (WTRU) may comprise a processor configured to receive a CSI resource configuration and a class indication. The CSI resource configuration may comprise information related to a grid-of-beams (GoB), an initial set of candidate beams, and a selection criteria. The GoB may comprise one or more beams. The processor may be further configured to determine a one or more beams for selection based on the initial set of candidate beams. The processor may be further configured to select one or more beams based on determined one or more candidate beams.

[0022] The processor further configured to send a CSI report message comprising information related to the selected one or more beams. The CSI resource configuration may comprise at least one of: an indication to partition the GoBs into sub-grids, an indication of an initial set of candidate beams in one or more sub-grids, an indication of a max or min amplitude level, or a window of amplitude levels to restrict the one or more beams from the initial set of candidate beams. The class indication may comprise Class A. The class indication may comprise Class B. The processor may be further configured to adjust the selection criteria based on any of available reporting resources, WTRU complexity, or target UCI omission.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0024] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0025] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0026] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0027] FIG. 2 is a diagram illustrating an example of Mode A bandwidth partitioning for CQI reporting.DETAILED DESCRIPTION

[0028] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, and / or broadcast to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 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), and the like.

[0029] As shown in FIG. 1 A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a CN 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the 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 a “STA”, may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit,a subscription-based unit, a pager, a cellular telephone, 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 (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a WTRU.

[0030] The communications systems 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 communication networks, such as the CN 106 / 115, the I nternet 110, and / or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0031] 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), and / or relay nodes. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be 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 for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0032] 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., radiofrequency (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).

[0033] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c 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 communication 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 UL Packet Access (HSUPA).

[0034] In an 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-A) and / or LTE-Advanced Pro (LTE-APro).

[0035] In an 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).

[0036] In an 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 implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., a eNB and a gNB).

[0037] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA20001X, 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), and the like.

[0038] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in alocalized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. 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 an 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 utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. 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 be required to access the Internet 110 via the CN 106 / 115.

[0039] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ 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 be utilizing a NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0040] 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 the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide 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) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 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.

[0041] 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 the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0042] FIG. 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include 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, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0043] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. 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 appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0044] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the 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 an 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 appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0045] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ 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.

[0046] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0047] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unitor 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. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and / or the 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, and the like. 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 a home computer (not shown).

[0048] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to the 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 cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0049] The processor 118 may also be coupled to the 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 in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It willbe appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0050] 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 e-compass, a satellite transceiver, a digital camera (for photographs and / or video), 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, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation 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.

[0051] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0052] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0053] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0054] Each of the eNode-Bs 160a, 160b, 160c 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, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0055] The CN 106 shown in FIG. 1 C 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 are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0056] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an 81 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. 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.

[0057] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0058] The SGW 164 may be connected to the 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.

[0059] 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 land-line communications devices. For example, the CN 106 may include, or may 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 the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0060] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0061] In representative embodiments, the other network 112 may be a WLAN.

[0062] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (I BSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad- hoc” mode of communication.

[0063] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the 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 in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), 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.

[0064] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0065] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 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, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0066] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11af and 802.11ah relative to those used in 802.11n, and 802.11 ac. 802.11af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine- Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0067] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 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) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0068] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0069] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0070] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any numberof gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 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 unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0071] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a 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 gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0072] 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 the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b,102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0073] 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 of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0074] The CN 115 shown in FIG. 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 are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0075] 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 serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized 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 162 may provide acontrol 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.

[0076] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating WTRU IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0077] The UPF 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 UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0078] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g. , an IP multimedia subsystem (IMS) server) that serves 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 the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0079] In view of Figures 1 A-1 D, and the corresponding description of Figures 1 A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab, UPF 184a-b, SMF 183a-b, DN 185a-b, and / or any other device(s) 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 to simulate network and / or WTRU functions.

[0080] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily i mplemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or may perform testing using over-the-air wireless communications.

[0081] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0082] Enhanced codebook subset restriction for PMI selection and overhead reduction may be described herein. CSI accuracy enhancement and feedback overhead reduction may be described herein. Codebook parameter(s) selection for performance enhancement and overhead reduction may be described herein.

[0083] An increase in the number of antenna ports may impact procedures in CSI frameworks, and may increase overhead for, in examples, the codebook subset restriction (CBSR), CSI (e.g., CQI and PMI) determination and reporting, and codebook parameters configuration. CSI frameworks may support two types of CBSR, Type-I and Type-ll CSI. In Type-I CBSR, the gNB may have full control of the beams restriction, also known as hard-CBSR. In Type-ll CBSR, the gNB may indicate certain beams to the WTRU, and an amplitude level for each of the indicated beams for soft-restriction.

[0084] CSI frameworks may support two types of CQIs, wideband CQI and sub-band CQI. The sub-band CQI may be determined on its own (e.g., sub-band CQI), or it may be determined as an offset from the wideband CQI (e.g., differential CQI). The type of sub-band CQI (e.g., actual or differential CQI) may be configured by the gNB. A WTRU may measure a sub-band CQI for each sub-band and reports it to the gNB. Even-odd numbered sub-band CQIs may be reported by the WTRU to a gNB with different priorities. Wideband PMI and / or sub-band PMIs (e.g., one or two) may be supported. The PMI reporting overhead may be a function of the number of antenna ports and the number of sub-bands.

[0085] In CSI frameworks, codebook oversampling values Oi and O2 may be configured by the gNB from a list of pre-defined values. The CSI quantization rules (e.g., rules for quantizing the beam-scaling coefficients) may be defined in the form of tables (e.g., one table for the beam-scaling amplitudes quantization and another table for phase quantization of the beam-scaling coefficients).

[0086] With an increase in the number of antenna ports, CBSR methods may cause excessive overhead (e.g., RRC and CSI overhead). Overhead related to CSI reporting and PMI reporting may increase, and opportunity for smaller O1 and O2 values for more efficient quantization of CSI with fewer bits increases.

[0087] Enhanced CBSR with CSI feedback overhead reduction may be described herein. Described herein may be how to reduce PMI search space and CSI feedback overhead by enhancing CBSR.

[0088] A WTRU may determine and recommend a subset of beams for PMI selection based on measurements and gNB configured parameters. The WTRU may receive a CSI resource configuration. The CSI resource configuration may comprise an indication to partition a grid-of-beams (GoB) into multiple subgrids (e.g., a grid of beams with M beams may be divided into multiple sub-grids with a number of beams in each sub-grid), indications of an initial set of candidate beams for restriction in one or more sub-grids, indications of a max amplitude level, a min amplitude level, and / or a window of amplitude levels to restrict one or more beams from the initial set of candidate beams.

[0089] The WTRU may receive a dynamic or a semi-static indication whether to use Class A, or Class B or both for beam restriction.

[0090] A WTRU may identify the strongest beam as the scaling reference. A WTRU may determine a relative amplitude, (e.g., a scaling factor for other beams with respect to the strongest beam). A WTRU may reduce the size of the GoBs.

[0091] A WTRU may use class A restriction. A WTRU may determine and / or restrict one or more beams from the initial set of candidate beams for restriction according to the configured selection criteria (e.g., max, min or a window of amplitude levels). In examples, some beams (e.g., all) with amplitudes not in the window may be restricted.

[0092] A WTRU may use class B restriction. A WTRU may determine and restricts one or more beams from the indicated GoBs and the initial set of candidate beams based on one or more of: amplitude level, (e.g., below a configured min threshold), and / or amplitude level threshold(s) adjusted by the WTRU. In examples, the number of restricted beams may be based on any or all of uplink resources available for UCI reporting, WTRU complexity, and / or target UCI omission. In examples of class B restriction, candidate set,and non-candidate sets may have different amplitude threshold(s) / window(s), which may be configured by gNB.

[0093] A WTRU may select a PMI from the remaining beams (e.g., non-restricted beams in the GoBs). In examples, for class A restriction, a WTRU may report a PMI. In examples, for Class B restriction, a WTRU may report restricted beams per sub-grid and / or the employed amplitude threshold for restriction. A WTRU may receive a confirmation when Class B restriction is indicated or configured. A WTRU may report a PMI based on the remaining beams (e.g., non-restricted beams in the GoBs).

[0094] CSI accuracy enhancement and feedback overhead reduction may be described herein. Methods and embodiments described herein may efficiently determine CQI in a large scheduled band and / or may report the CQI with minimum overhead. A scheduled band may be divided into multiple segments. Subband CSI (e.g., CQI or PMI) may be reported for the segments where CSI variation is large.

[0095] A WTRU may receive a CSI configuration. A CSI configuration may comprise an indication to partition the scheduled band into multiple segments with the number (e.g., same or different) of sub-bands in each segment, an indication of the number of time and / or frequency resources available for CSI reporting (e.g., the total number of CQIs that may be reported), and / or an indication of Mode A or Mode B.

[0096] For Mode A, in examples, a WTRU may receive an indication of the number of segments in the scheduled band (e.g., A=2 segments in the scheduled band). For Mode B, in examples A WTRU may receive, an indication of the maximum and minimum number of segments (e.g., Amax=4, Amm=2), an indication of the maximum and minimum number of sub-bands in each segment (e.g., Bmm-1 and Bmax-4), and / or a threshold associated with determining whether to report a wideband CQI.

[0097] A WTRU may partition the scheduled band into multiple segments. In examples, for Mode A, a WTRU may partition the scheduled band into two or more segments (e.g., into A number of segments with equal number of sub-bands in each segment). In examples, for Mode B, a WTRU may partition the scheduled band into two or more segments (e.g., into C segments, where Bmin - C Bmax).

[0098] A WTRU may determine the number of segments and the number of sub-bands in each segment based on channel variations (e.g., CQI variations).

[0099] For example, a larger number of segments may be chosen if the sub-band CQI variations is large; a smaller number of segments may be chosen if the sub-band CQI variations is small.

[0100] A WTRU may determine a CQI type per segment (e.g., actual or differential sub-band / segment CQI). In examples, the determination may be based on at least one of sub-band channel variations (e.g., sub-band CQI variations in a segment) and / or uplink resources available for CQI reporting. For example,the determination may be the actual CQI if the channel variations are large and differential CQI if the channel variations are low.

[0101] A WTRU may determine a wideband CQI, segment CQIs, and / or sub-band CQI. In examples, Segment CQI may be wideband CQI plus Differential segment CQI. In examples, Sub-band CQI may be Wideband CQI plus Differential segment CQI plus Differential sub-band CQI.

[0102] A WTRU may identify segment index(es) by comparing sub-band CQIs in the segments. In examples, one or more segment(s) with the highest sub-band CQIs may be selected, and / or a segment with the highest sub-band CQI variations may be selected.

[0103] A WTRU may determine whether to report a wideband CQI. A WTRU may report a wideband CQI when the number of actual segment CQI (s) is less than a configured threshold.

[0104] A WTRU may report a CSI. A WTRU may report a CSI comprising Wideband CQI (e.g., for Mode A and / or Mode B). In examples, a WTRU may report wideband CQI based on an indicator to indicate whether wideband CQI is reported or not, an indicator to indicate the wideband CQI (e.g., if reported).

[0105] A WTRU may report a CSI comprising actual and / or differential CQIs. A WTRU may report a CSI comprising actual and / or differential CQIs based on an indicator to indicate if the reported segment and / or sub-band CQIs are actual or differential CQIs and / or an indicator to indicate a reference CQI for differential CQI reporting (e.g., reference for sub-band CQI and / or a reference for differential CQI).

[0106] A WTRU may report a CSI comprising sub-band CQI. A WTRU may report a CSI comprising subband CQI based on an indicator to indicate the segment indices of the reported sub-band CQIs, an indicator to indicate the number of reported sub-band CQIs in each segment, an indicator to indicate the sub-band indices of the reported sub-band CQIs in a segment, and / or an indicator to indicate the sub-band CQIs.

[0107] A WTRU may report a CSI comprising segment CQI. A WTRU may report a CSI comprising segment CQI based on an indicator to indicate the segment CQIs. For Mode B, in examples, a WTRU may report a CSI based on an indicator to indicate the number of segments in the scheduled band and the number of sub-bands in each segment.

[0108] Codebook parameter(s) selection may be described herein. A PMI may be selected from a codebook. If the PMI’s parameters do not adapt to the channel variations, the selected parameters may cause performance degradation and / or feedback overhead. In examples, the oversampling values of the codebook and / or the quantization rules for CSI may be recommended to the gNB by a WTRU (e.g., based on channel variations).

[0109] A WTRU may receive a CSI configuration. The CSI configuration may comprise an indication of one or more codebook oversampling values (e.g., (Oij" and (O2)~ ), an indication of one or more rules or tables for CSI quantization (e.g., amplitude and / or phase quantization of the beam scaling coefficients), and / or one or more thresholds to assist the selection of an amplitude and phase quantization rule. In examples, the rules may be Rule_A1 , Rule_A2, .., Rule_AN for amplitude quantization. In examples, the rules may be Rule_P1 , Rule_P2, ...., Rule_PN for phase quantization.

[0110] A WTRU may determine a 1st codebook using the configured (Oij" and (02^ oversampling values. A WTRU may derive a 2nd codebook by adjusting the configured (Oi)~ and (O2)~ oversampling values to new oversampling values.

[0111] In examples, the (Oi)~ and (O2)~ adjustment into Oi and O2 may be based on at least one of the following: target BLER, Uplink resources for CSI, doppler, and / or location.

[0112] In examples of codebook oversampling value adjustment based on target BLER, if the PMI selected from a codebook with (Oi)~ and (O2)~ values does not meet a target BLER a WTRU may increase the (Oi)~ and (O2) values to O1 and O2. In examples, if the target BLER performance can be achieved using a PMI selected from a codebook with oversampling O1 and O2, a WTRU may decrease the (Oi)~ and (O2)~ values to O1 and O2.

[0113] In examples of codebook oversampling value adjustment based on uplink resources for CSI, a WTRU may decrease the (Oi)~ and (O2)~ values to O1 and O2 if the uplink resources for CSI are not sufficient.

[0114] In examples of codebook oversampling value adjustment based on doppler, a WTRU may adjust (Oi)~ and (O2)~ into smaller values at high doppler, and / or larger values at low doppler and vice-versa.

[0115] In examples of codebook oversampling value adjustment based on location, a WTRU may adjust (Oi)~ and (O2)~ based on a location of a WTRU (e.g., larger O1 and O2 for cell-edge WTRUs, smaller O1 and O2 values for closer WTRUs).

[0116] A WTRU may determine a PMI from the 2nd codebook including beam-scaling coefficients based on frequency-unit (e.g., per sub-band), antenna element (e.g., per polarization if a gNB use dual-polarized antennas), and / or time-unit (e.g., per slot, if the reporting window of a determined PMI is more than one slot).

[0117] A WTRU may determine a beam-scaling amplitude quantization rule from the indicated and / or available ones based on at least one of a strength of the determined beam scaling amplitudes, (e.g., each of the beam scaling amplitudes may be identical in their coefficient value), and / or variation among thedetermined beam scaling amplitudes (e.g., the variance of the beam-scaling coefficients may be larger than a threshold). In examples, a WTRU may quantize stronger beam-scaling amplitude coefficients with smaller variance using a quantization rule / table denser around higher amplitude values (e.g., 1 and coarser around smaller amplitude values, 0). In examples, a WTRU may quantize weaker beam-scaling amplitude coefficients with smaller variance using a quantization rule denser around smaller coefficient values (e.g., 0 and coarser around higher amplitude values, 1).

[0118] A WTRU may determine a beam-scaling phase quantization rule (e.g., from the indicated or available ones) based on phase discrepancy among the determined phase coefficients of the beam-scaling coefficients. In examples, a WTRU may quantize the phase coefficients using a quantization rule covering a larger set of phases (e.g., 0-360 degree when the phase discrepancy is higher). In examples, a WTRU may quantize the phase coefficients using a quantization rule covering a smaller set of phases (e.g., 0-180 degree when the phase discrepancy is lower).

[0119] A WTRU may report a CSI . A WTRU may report a CSI comprising one or more of an indication of the adjusted Oi and O2 values, a PMI based on the adjusted O1 and O2 values, an indication of the quantization rule for amplitude quantization (e.g., Rule_A1), and / or an indication of the quantization rule for phase quantization (e.g., Rule_P1).

[0120] A WTRU may report a subset of channel state information (CSI) components. CSI components may comprise any and / or all of: a CSI-RS resource indicator (CRI) (e.g., a CRI may indicate CSI-RS resource(s) (e.g., one resource) out of a CSI-RS resource set), a SSB resource indicator (SSBRI) which may indicate SSB(s) out of a set of SSBs (e.g., one SSB), an indication of a panel used for reception at the WTRU (e.g., a panel identity or group identity), measurements, and / or other channel state information (e.g., a least rank indicator (Rl), channel quality indicator (CQI), precoding matrix indicator (PMI), and / or a Layer Index (LI)). Measurements of a CSI component may comprise, for example, a L1-RSRP, L1-SINR taken from SSB or CSI-RS (e.g. cri-RSRP, cri-SINR, SSB-lndex-RSRP, and / or SSB-I ndex-SINR).

[0121] In examples, a signal may be a sounding reference signal (SRS), a channel state information - reference signal (CSI-RS), a demodulation reference signal (DM-RS), a phase tracking reference signal (PT-RS), and / or a synchronization signal block (SSB).

[0122] In examples, a channel may be a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), and / or a physical random-access channel (PRACH).

[0123] Downlink reception may comprise Rx occasion, PDCCH, PDSCH, and / or SSB reception. Uplink transmission may comprise Tx occasion, PUCCH, PUSCH, PRACH, and / or SRS transmission. RS may comprise one or more of RS resources, RS resource set, RS port, and / or RS port group. RS may comprise SSB, CSI-RS, SRS, and / or DM-RS. A time instance may be a slot, symbol, and / or subframe.

[0124] Enhanced CBSR with CSI feedback overhead reduction may be described herein. New Radio (NR) may define a set of precoders in the form of a codebook. The codebook may include a set of PMIs. A PMI may be a codeword of complex numbers having a length equal to the number antenna ports at the gNB. In examples, to acquire a PMI, a gNB may configure a reference signal (RS) (e.g., a channel state information RS (CSI-RS)) toward a WTRU. The WTRU may measure the CSI-RS, and may perform a search across the PMIs of the codebook to determine a PMI (e.g., the best PMI). A WTRU may report the PMI to the gNB (e.g., in a CSI report). The gNB may update and / or correct the reported PMI. The gNB may apply the PMI across the antenna ports to generate a beam for downlink transmission.

[0125] The complexity of searching a PMI and the overhead of reporting the selected PMI may depend on the number of codepoints and / or PMIs in the defined codebook. The number of PMIs in the codebook may depend on the number of CSI-RS ports and / or the discrete Fourier transform (DFT) oversampling parameter of the codebook. In examples, the number of PMIs in the codebook may be quantified as N1N2O1O1. NI may be a number of dual-polarized antenna ports on the first dimension. N2may be a number of dual-polarized antenna ports on the second dimension of the antenna panel at the gNB. Oi and O2 may be DFT oversampling values for the first and second dimension, respectively. The number of ports and the DFT oversampling may be configured in the CSI configuration.

[0126] In NR, a gNB may restrict a WTRU from measuring and reporting certain beams of the codebook using codebook subset restriction (CBSR). NR may support types of CBSR methods. For example, hard- CBSR and soft-CBSR. In hard-CBSR, a gNB may indicate a beam to the WTRU as a restricted beam. For soft-CBSR, a gNB may indicate a set of beams to the WTRU, and / or a reference amplitude level for each beam. Hard and soft-CBSR may be RRC configured. A WTRU may classify an indicated beam as a restricted beam or non-restricted beam by comparing the indicated reference amplitude level of beam to its measured level. In a multiple-antenna array system, the overhead of CBSR and PMI reporting may increase when the number of antenna-ports increases. Methods and embodiments described herein may reduce CBSR overhead, PMI overhead, and / or PMI search complexity.

[0127] Configuration details may be described herein. In examples, a WTRU may receive a dynamic and / or semi-static CSI configuration (e.g., by RRC, MAC-CE, DCI). A CSI configuration may comprise oneor more of the following, including an indication of the number of antenna-ports and / or the DFT- oversampling values, an indication to partition the codebook or the grid-of-beams (GoBs) into multiple subgrids with equal or different number of beams in each sub-grid, an indication to the WTRU to partition the GoBs into less than X2 and / or X2 number of sub-grid where X2< N^O^, an indication to restrict one or more beams in one or more sub-grids. The CSI configuration may comprise an indication to report one or more of the WTRU determined restricted and / or un-restricted beams according to the configured reference amplitude level criteria (e.g., Class A restriction) and / or to report one or more of the beams classified by the WTRU {e.g., autonomously) as restricted and / or un-restricted (e.g., Class B restriction). The CSI configuration may comprise a dynamic and / or semi-static indication (e.g., by RRC, MAC-CE, and / or DCI) on whether to use Class A, or Class B, or both Class A and Class B for beams restriction. The CSI configuration may comprise an indication of a rule, one or more parameters of a rule (e.g., variable values of an equation representing a rule), and / or an index of a pre-defined table to be used for assigning a relative strength and / or amplitude level to the beams other than the strongest beam.

[0128] A WTRU may receive a CSI configuration comprising an indication to partition the codebook and / or the grid-of-beams (GoBs) into multiple sub-grids with a number of beams (e.g., equal or different) in each sub-grid. In examples, a WTRU may receive an indication to partition the GoB with W1W2O1O2beams into two sub-grids each having N1N2O1O2 / 2 beams. In examples, a WTRU may receive an indication to partition the GoB with N1N2O1O2beams into two grids, with sub-grid_1 having 1 ,• -,Xi beams and sub- grid_2 having Xt+ 1, ■■■,NlN2O.]O2beams, where X #= N1N2O1O2 / 2.

[0129] A WTRU may receive a CSI configuration comprising an indication to restrict one or more beams in one or more sub-grids. If a CSI configuration comprises an indication to restrict one or more beams in one or more sub-grids, a WTRU may receive an indication of one or more sub-grids (e.g., a WTRU may receive an indication of sub-grid_1 and sub-grid_3 to restrict one or more beams in the indicated sub-grids), an indication of one or more beams in one or more sub-grids, (e.g., an indication of at least one beam in sub- grid_1 and sub-grid_3), an indication of at least one beam in more than one sub-grid, and / or an indication of a reference amplitude level in a frequency, time, and / or spatial unit for at least one beam in one or more sub-grids. A WTRU may receive a reference amplitude level (e.g., a minimum amplitude level and / or a maximum amplitude level) in a frequency-unit(s), time-unit(s), and / or spatial-unit(s) for at least one beam in one or more sub-grids. A WTRU may receive one or more reference amplitude level(s) for one or more sub-grids. A WTRU may receive a common reference amplitude level for more than one beam in one or more sub-grids.

[0130] A WTRU may receive a CSI configuration comprising an indication to report one or more of the WTRU determined restricted and / or un-restricted beams according to the configured reference amplitude level criteria (e.g., Class A restriction) and / or to report one or more of the beams autonomously classified by the WTRU as restricted and / or un-restricted (e.g., Class B restriction). In examples, a WTRU may receive an indication to report restricted and / or un-restricted beams, which may be based on Class A and / or Class B restriction. In examples, if a WTRU is configured with Class B restriction, the WTRU may further be configured with an integer value n and / or m.

[0131] A WTRU may receive a dynamic and / or semi-static indication (e.g., by RRC, MAC-CE, and / or DCI) on whether to use Class A, Class B, or Class A and Class B for beams restriction.

[0132] A WTRU may receive an indication of a rule, one or more parameters of a rule (e.g., variable values of an equation representing a rule), and / or an index of a pre-defined table to be used for assigning a relative strength or amplitude level to the beams other than the strongest beam.

[0133] In examples, there may be a first set of beams. The first set of beams may comprise one or more beam(s) in the GoBs whose relative strength and / or relative amplitude level is less than the configured minimum reference amplitude level and higher than the configured maximum reference amplitude level.

[0134] In examples, there may be a second set of beams. The second set of beams may comprise one or more beam(s) whose relative strength and / or relative amplitude level is higher than the configured minimum reference amplitude level and less than the configured maximum reference amplitude level.

[0135] In examples, there may be a third set of beams. The third set of beams may comprise one or more gNB indicated beams in the GoBs whose relative strength and / or relative amplitude level is higher than the configured minimum reference amplitude level and less than the configured maximum reference amplitude.

[0136] In examples, there may be restricted beams. The first set of beams may also comprise the restricted beams. In examples, there may be un-restricted beams. The second and third set of beams may comprise the un-restricted beams.

[0137] Overhead of CBSR, overhead of PMI reporting, and / or the complexity of a WTRU may be reduced, in examples, by reducing PMI search complexity. To reduce overhead, a WTRU may identify a strongest beam across one or more frequency-units (e.g., sub-bands), time-units (e.g., slots), and / or spatial-units (e.g., antenna ports and / or antenna polarization if a gNB uses dual-polarized antennas), and / or among DFT-beams (e.g., all) and may use it as a reference for assigning a relative strength value and / or amplitude value to the remaining beams across one or more frequency, time and / or spatial-units based on a fixed and / or a configured rule. In examples, a WTRU may identify the strongest beam across configured sub-bands (e.g., all configured sub-bands) and assign an amplitude value (e.g., amplitude value 1) to it. A WTRU may use the strongest beam to assign a relative strength and / or amplitude value to the remaining beams across configured sub-bands (e.g., all configured sub-bands) based on a rule (e.g., a fixed and / or configured rule). A WTRU may reduce the number of PMIs, codepoints, and / or beams in a codebook and / or GoBs using Class A and / or Class B restriction.

[0138] Class A restriction may be described herein. A WTRU may be configured to restrict one or more beams according to Class A restriction. For Class A restriction, the WTRU may follow the gNB configured reference amplitude levels (e.g., a maximum reference amplitude level, a minimum amplitude level) and / or a window of reference amplitude levels to restrict one or more beams in the GoBs. If configured with Class A beam restriction to determine the set of restricted beams (e.g., a 1st set of beams), a WTRU may determine a relative amplitude level, and / or a relative strength of a beam based on the strongest beam in one or more frequency-units, time-units, and / or spatial-units.

[0139] If configured with Class A beam restriction, a WTRU may classify a beam as a restricted beam if its relative amplitude level and / or relative strength is less than the configured minimum reference amplitude level. For example, a WTRU may assume that all the beams with their relative strengths and / or relative amplitude levels less than the configured minimum reference amplitude level may result in a smaller performance (e.g., a higher BLER).

[0140] If configured with Class A beam restriction, a WTRU may classify a beam as a restricted beam if its relative amplitude level and / or relative strength is higher than the configured maximum reference amplitude level. For example, a WTRU may assume that all the beams with their relative strengths and / or relative amplitude levels higher than the configured maximum reference amplitude level may cause harmful interference to other users in the same geographical location and / or other geographical locations.

[0141] If configured with Class A beam restriction, a WTRU may classify a beam as a restricted beam if its relative amplitude level and / or relative strength is outside of the configured strength and / or amplitude level reference window (e.g., a maximum reference amplitude level and a minimum reference amplitude level). For example, a WTRU may assume that all the beams with their relative strengths and / or relative amplitude levels outside the configured reference window may cause performance degradation and / or harmful interference to other WTRUs.

[0142] Class B restriction may be described herein. A WTRU may be configured to restrict one or more beams according to Class B restriction. For Class B restriction, a WTRU may restrict beams like Class A restriction, and / or restrict one or more beams based on other additional conditions, situations,requirements, and / or criteria as determined by the WTRU. In examples, a WTRU may restrict one or more beams in the 2nd set of beams (e.g., for Class B restriction only).

[0143] In examples, if configured with Class B restriction, a WTRU may restrict one or more beams in the GoBs as in Class A restriction. In examples, if configured with Class B restriction, a WTRU may restrict one or more beams whose relative amplitude strengths and / or relative amplitude levels is higher than the configured minimum reference amplitude level and / or lower than the configured maximum reference amplitude level based on at least one of the following.

[0144] In examples, if configured with Class B restriction, a WTRU may restrict one or more beams based on uplink resources available for UCI reporting. A WTRU may adjust the number of beams in the 1st, 2nd and / or 3rd set of beams by adjusting the configured minimum and / or maximum reference amplitude level(s). A WTRU may adjust the minimum reference amplitude level by Ajnin to increase the number of beams in the 1st set of beams. A WTRU may adjust the maximum reference amplitude level by A_max to decrease the number of beams in the 2nd and / or 3rd set of beams. A WTRU may consider (e.g., autonomously) other beams for potential restation (e.g., other beams not configured and / or indicated by gNB by for potential restriction). In examples, a WTRU may be indicated with a beam index (e.g., a beam with index i) and / or a reference amplitude level (e.g., a maximum and / or a minimum reference amplitude). A WTRU may use the configured and / or indicated reference amplitude level for a beam with index i to restrict one or more beams around the beam with index I (e.g., beams with indices i + l,i - l,i + 2, i - 2,i - n,i +m, where nm or n = m. Alternatively, or additionally, a WTRU may adjust the configured and / or indicated reference amplitude level for a beam with index i to restrict one or more beams around the beam with index I (e.g., beams with indices i + 1, i - 1, i + 2, i - 2, i - n, i + m).

[0145] In examples, if configured with Class B restriction, a WTRU may restrict one or more beams based on WTRU complexity. A WTRU may adjust the number of beams in the 2nd and / or 3rd set of beams to reduce a PMI search complexity. In examples, a WTRU (e.g., a computationally constrained WTRU) may reduce the PMI search space size by increasing the number of beams in the 1st set of beams and decreasing the number of beams in the 2nd and / or 3rd set of beams. The WTRU may spend less computational resources to search a PMI from the 2nd and / or 3rd set of beams. A WTRU may reduce the PMI search space and / or the number of beams in the 2nd and / or 3rd set of beams using at least one of the methods and / or procedures mentioned earlier.

[0146] In examples, if configured with Class B restriction, a WTRU may restrict one or more beams based on target UCI omission. A WTRU may adjust the number of beams in the 2nd and / or 3rd set of beams. Inexamples, the UCI omission of a particular CSI may not be determined to be needed. In examples, the UCI omission of a portion of a Type-ll CSI report carrying the PMI may not be determined to be needed (e.g., due to constraint on the uplink resources available for UCI).

[0147] CSI determination may be described herein. A WTRU may be configured and / or indicated dynamically and / or semi-statically (e.g., by RRC, MAC-CE, and / or DCI) to determine a CSI based on the 1st, 2nd, and / or 3rd set of beams. A WTRU may determine a CSI e.g., a PMI, Rl, and / or CQI) based on the configured 1st, 2nd, and / or 3rd set of beams.

[0148] CSI reporting may be described herein. In examples (e.g., for Class A restriction), a WTRU may report the determined CSI in a CSI report. In examples (e.g., for Class B restriction), a WTRU may report a CSI. The CSI report may comprise one or more of the determined CSI (e.g., PMI, CQI, and / or Rl), adjusted reference amplitude levels (e.g., Amin and Amax), indices of additional beams outside the 1st and 2nd set of beams considered for restriction (e.g., beams with indices i + 1, i - 1, i + 2, i - 2, i - n, i + m around an indicated beam i), an indication to re-configure and / or update the values of n and / or m, and / or an indication to indicate the value n and m used by the WTRU. The CSI report may comprise an indication of the motivation and / or reason behind a WTRU performing Class B restriction (e.g., WTRU performed Class B restriction due to limited resources available for uplink UCI and / or WTRU complexity, and / or UCI omission.), an indication to recommend to the gNB to switch from Class A restriction to Class B restriction, an indication to recommend to the gNB to adjust or reconfigure the reference amplitude levels, and / or an indication to the gNB to confirm the 2nd and / or 3rd set of beams for CSI determination for one or more future CSI reports.

[0149] A WTRU may be configured with Class B restriction, and may receive a response, update, and / or confirmation for one or more requests and / or recommendations. In examples, a WTRU may receive a: response of the adjusted Amin and Amax, a response of the additional restricted beam indices (e.g., beams with indices i + 1, i - 1, i + 2, i - 2, i - n, i + m, a response of the requested n and m, and / or a response and / or confirmation of Class B restriction. A WTRU may determine and / or report a CSI for the 2nd or 3rd set of beams (e.g., after receiving a response, update and / or confirmation).

[0150] CSI accuracy enhancement and feedback overhead reduction may be described herein. There may be types of CQI supported in NR. NR may support wideband CQI and sub-band CQI. Wideband CQI may provide a holistic view of the channel quality across a bandwidth (e.g., the entire bandwidth) using a single value. Wideband CQI may be utilized when channel characteristics are similar (e.g., uniform) across the entire bandwidth. Wideband CQI may be utilized for less frequency-selective channel conditions and / orfor high mobility scenarios (e.g., where detailed frequency domain information may be less relevant). Wideband CQI may be utilized for situations where the system complexity and / or reporting may be minimized.

[0151] Sub-band CQI may provide a more granular view of the channel. For sub-band CQI, bandwidth (e.g., the total bandwidth) may be divided into smaller frequency bands. Sub-band channel quality may be measured and / or reported by the WTRU (e.g., for each sub-band). The gNB may make decisions for frequency-selective scheduling (e.g., based on the sub-band reporting). Sub-band CQI may enhance spectral efficiency (e.g., for low-mobility users). The sub-band CQI may be determined on its own, which may be actual sub-band CQI. The sub-band CQI may be determined as an offset from the wideband CQI, which may be differential CQI. The type of sub-band CQI (e.g., actual or differential CQI) may be configured by a gNB. Even and odd-numbered sub-band CQIs may be reported by the WTRU to a gNB with different priorities. CQI overhead may increase with the number of sub-bands in a wideband.

[0152] PMI may be relevant to optimizing MIMO transmissions in NR. PMI may provide the gNB with the information about the precoding matrix to use. Wideband PMI may provide a precoding matrix (e.g., singular) applicable to a transmission (e.g., the entire bandwidth). In examples, channel conditions may be similar across a frequency band (e.g., where channel is less frequency-selective or when users are experiencing high mobility). Sub-band PMI may divide the entire bandwidth into smaller frequency segments. In examples, a WTRU may measure and / or report a precoding matrix (e.g., for each frequency segment). Sub-band PMI may provide spectral efficiency improvements (e.g., for low-mobility users benefiting from tailored beamforming strategies in specific frequency ranges). PMI reporting overhead may be a function of the number of antenna ports and / or the number of sub-bands.

[0153] Methods and / or embodiments to enhance CSI in terms of CQI and PMI accuracies or / and reducing their feedback overhead may be described herein. Described herein may be solutions wherein sub- wideband segments may be introduced in a wideband, and sub-band CSI (e.g., CQI and PMI) may be reported for the segments (e.g., only) where the CSI variation is deemed large.

[0154] WTRU CSI configuration may be described herein. A WTRU may receive a CSI configuration through an RRC configuration, MAC CE, DCI, and / or a combination thereof for sub-band-based CSI reporting. The CSI may be a CQI, and / or PMI. A partitioning procedure may performed for the scheduled bandwidth. In examples, the partitioning procedure may be applicable for partitioning of CSI over the span of a BWP and / or band.

[0155] The received CSI configuration may comprise an indication to partition the scheduled band into multiple segments with the same and / or different number of sub-bands in each segment.

[0156] The received CSI configuration may comprise an indication of the total number of CQIs to be reported. In a solution, a WTRU may receive the number of time / frequency resources for CQI reporting (e.g., based on the uplink grant size for CSI reporting). The configured time and / or frequency domain parameters may comprise number, size, periodicity, and / or offset associated with CQI reporting. Alternatively or additionally, a WTRU may receive an indication for the sub-band size, and may determine the number of CQIs for reporting based on the sub-band size.

[0157] The received CSI configuration may comprise an indication to use a specific modes of partitioning for CQI sub-band reporting. In examples, a WTRU may be configured in one of Mode A, Mode B,...Mode N. In examples, for a mode of partitioning (e.g., Mode A, Mode B), there may be an associated strategy for determining a number of segments and / or number of sub-bands per segments for CQI reporting.

[0158] The received CSI configuration may comprise one or more threshold for each modes of partitioning that may be used for determination of the number of segments and / or sub-bands. The threshold may be based on a measure of frequency-selectiveness of the channel, mobility of users, number of antenna ports, the size of scheduled bandwidth, and / or BWP size.

[0159] Partitioning of the scheduled bandwidth for CQI reporting may be described herein. A WTRU may partition bandwidth into multiple segments based on Mode A. In examples, for Mode A, a WTRU may be provided with parameters for partitioning of bandwidth for CQI reporting.

[0160] FIG. 2 is a diagram 200 illustrating an example of Mode A bandwidth partitioning for CQI reporting. In examples, for Mode A, a WTRU may be configured with some basic parameters for partitioning. A WTRU may report CQI with different resolution in frequency domain based on provided parameters.

[0161] In examples, for Mode A (e.g., A1), NJotal may comprise the configured number of CQI to report. A WTRU may partition the scheduled bandwidth to a number of segments N_seg (e.g., N_seg=2). For a first segment, a WTRU may report a single wideband CQI. For a second segment, the WTRU may report (NJotal - 1) sub-band CQI values. NJotal may comprise the total number of CQI and N_seg, the number of segments may be dynamically indicated and / or configured.

[0162] A WTRU may report NJotal CQI values. In examples, a WTRU may receive an implicit and / or explicit indication from the gNB for which segment(s) may be associated to the wideband CQI. Alternatively or additionally, the WTRU may indicate the segment(s) associated with wideband CQI. In examples, a WTRU may send a bitmap comprising the location of the segment(s) with wideband CQI may be flagged bya 1 or 0. In examples, a WTRU may send an index representing the segments associated with the wideband CQI.

[0163] In examples, for Mode A (e.g., A2), NJotal may comprise the configured number of CQI to report. A WTRU may partition the scheduled bandwidth to a number of segments N_seg, (e.g., Nsegz2). For a first segment, the WTRU may report M sub-band CQI values. For a second segment, the WTRU may report (NJotal - M) sub-band CQI values. In examples, the span of the sub-band in the first and second segments may be unequal. N otal may comprise the total number of CQI, M. The number of sub-band CQIs for a first segment and N_seg, the number of segments, may be dynamically indicated and / or configured. In examples, a WTRU may report NJotal CQI values based on a configured grant.

[0164] In examples (e.g., N_seg=2), a WTRU may receive an indication from gNB (e.g., implicit and / or explicit) as to which segment may be associated to M sub-band CQI values, and / or which to (NJotal - M) sub-band CQI values. In examples (e.g., N_seg-2), the WTRU may indicate the segment associated with M sub-band CQI values and / or (NJotal - M) sub-band CQI values. In examples, a WTRU may send a bitmap to report the segment(s) with M and / or (NJotal - M) sub-band CQI values, where they may be flagged by a 1 or 0. In examples, a WTRU may send an index representing segment(s) (e.g., an index of each segment).

[0165] In examples, for Mode B, a WTRU may be provided with a range of possible number of segments for partitioning of the scheduled bandwidth for CQI reporting. Then, WTRU may autonomously determine and / or partition the scheduled wideband into a number of segments. The WTRU may partition each segment into a number of sub-bands.

[0166] In examples of Mode B, NJotal may comprise the configured number of CQI to report. Based on frequency selectivity of channel, a WTRU may determine a number of segments and / or a number of subbands in each segment such that the number of segments may be confined within a range of configured parameters (e.g., Bmin and Bmax). For example, based on frequency selectivity of channel variations, the number of segments for partitioning and reporting may be changed. In examples, per configured grant, a WTRU may report NJotal CQI values.

[0167] In examples, a WTRU may not report the information related to the association of each segment to the type of CQIs with every CQI report.

[0168] In examples, a WTRU may receive a configuration. A WTRU may receive a configuration to report the association information every X slots, where X may be a configured and / or indicated value. Alternatively or additionally, the configuration may indicate a change in association and may request for an additionaluplink grant to indicate the association information. A WTRU may implicitly indicate a change in association information, for examples, by reporting a specific CQI and / or combination of CQI values.

[0169] WTRU CSI type determination may be described herein.

[0170] A WTRU may determine a CQI type based on segment CQI, for example, actual and / or differential segment CQI e.g., Segment CQI = wideband CQI + differential segment CQI).

[0171] A WTRU may determine a CQI type based on sub-band CQI, for example, actual and / or differential sub-band CQI (e.g., Sub-band CQI - wideband CQI + differential segment CQI + differential sub-band CQI).

[0172] The determination may be based on at least one of channel variations, the variance of the CQI, and / or uplink resources available for CQI reporting. The determination may be based on channel variations (e.g., sub-band CQI variations in a segment). In examples, the determination may comprise actual CQI if the channel variations may be large and differential CQI if the channel variations may be low. The determination may be based on comparing the variance of the CQI with a configured threshold. The configured thresholds for segment CQI and / or sub-band CQI may be the same or different.

[0173] A WTRU may identify segment index(es) by comparing sub-band CQIs in the segments. In examples, one or more segment(s) with the highest sub-band CQIs may be selected, and / or a segment with the highest sub-band CQI variations may be selected. A WTRU may determine whether to report a wideband CQI. In examples, a WTRU may report a wideband CQI (e.g., only if the number of actual segment CQI (s) is less than a configured threshold)

[0174] WTRU CSI selection for reporting may be described herein. A WTRU may select for CSI reporting. In examples, a WTRU may select wideband CQI for CSI reporting when: variance of segment CQI may be less than threshold_a0, variance of sub-band CQI may be less than threshold_bO, the difference between segment CQI and average sub-band CQI may be less than a threshold, and / or segment CQI / average subband CQI and wideband CQI may be less than a threshold.

[0175] In examples, a WTRU may select segment CQI for CSI reporting when: segment CQIs are actual, variance of segment CQI may be less than threshold_a0, and / or variance of sub-band CQI may be less than threshold_bO.

[0176] In examples, a WTRU may select wideband and segment CQIs for CSI reporting when: segment CQIs may be differential, variance of segment CQI may be greater than threshold_a0, and / or variance of sub-band CQI may be less than threshold_bO.

[0177] In examples, a WTRU may select segment and sub-band CQI for CSI reporting when: segment CQIs may be actual, and / or variance of sub-band CQI may be greater than threshold_bO.

[0178] In examples, a WTRU may select wideband, segment, and sub-band CQI for CSI reporting when: segment CQIs may be differential, variance of segment CQI may be greater than threshold_aO, and / or variance of sub-band CQI may be greater than threshold_bO.

[0179] WTRU CSI resolution may be described herein. A WTRU may determine how many bits to be used for quantizing a CQI based on segment CQI. In examples, the number of bits to quantize segment CQI may depend on one or more of actual / differential segment CQI, uplink UCI grant, and / or a difference between wideband CQI and segment CQI (e.g., wideband CQI may be a variance of segment CQI, wideband CQI may be average segment CQI). In examples, there may be more bits if the difference is large and vice versa (e.g., X number of bits if the difference is greater than Y).

[0180] A WTRU may determine how many bits to be used for quantizing a CQI based on sub-band CQI. In examples, the number of bits to quantize for sub-band CQI depends on one or more of actual / differential sub-band CQI, uplink UCI grant, difference between wideband CQI, segment CQI and / or sub-band CQI. For example: Wideband CQI - (Variance of segment CQI - variance of sub-band CQI); Wideband CQI - (Average segment CQI - average sub-band CQI); Segment CQI - variance of sub-band CQI; and / or Segment CQI - average of sub-band CQI.

[0181] WTRU CSI reporting may be described herein. A WTRU may report a CSI based on a number of factors.

[0182] In examples, for both Mode A and Mode B, the CSI may comprise wideband CQI based on an indicator to indicate if wideband CQI may be reported or not, and / or an indicator to indicate wideband CQI (if reported).

[0183] In examples, for both Mode A and Mode B, the CSI may comprise actual and / or differential CQIs based on an indicator to indicate if the reported segment and / or sub-band CQIs may be actual and / or differential CQIs, and / or an indicator to indicate a reference CQI for differential CQI reporting (e.g., reference for sub-band CQI and / or a reference for differential CQI).

[0184] In examples, for both Mode A and Mode B, the CSI may comprise sub-band CQI based on an indicator to indicate the segment indices of the reported sub-band CQIs, an indicator to indicate the number of reported sub-band CQIs in each segment, an indicator to indicate the sub-band indices of the reported sub-band CQIs in a segment, and / or an indicator to indicate the sub-band CQIs.

[0185] In examples, for both Mode A and Mode B, the CSI may comprise segment CQI based on an indicator to indicate the segment CQIs.

[0186] In examples, for Mode B, the WTRU may report the CSI based on an indicator of the number of segments in the scheduled band and the number of sub-bands in each segment.

[0187] Codebook parameters selection may be described herein. WTRU oversampling determinations may be described herein.

[0188] The precoding codebook may comprise of indices that may map a set of phase / amplitude that the WTRU may apply to an antenna element and / or antenna port (e.g., one-to-one). For example, the codebook may be defined as a matrix. A column of the codebook matrix may correspond to a precoding vector of length, N. N may correspond to a number of transmit antennas {e.g., N=N1*N2). N1 antennas may be in the vertical dimension, and N2 antennas may be in the horizontal dimension (e.g., for a square arrangement of antennas, for a uniform linear array). N may be defined per antenna group and / or across antenna groups. An antenna group may correspond to a group of coherent antennas (e.g., an antenna panel). A WTRU may report (e.g., as part of its capability) that it may be equipped with Ng antenna groups.

[0189] A codebook may be a DFT matrix with linearly independent columns. To generate a codebook with finer resolution, a WTRU may be configured with oversampling factors (Oi )~ and (Ozf which may be associated with the vertical and horizontal dimension, respectively. A codebook and / or parameters may be RRC configured, and may remain static unless the network issues an RRC reconfiguration command (e.g., to the WTRU). Oversampling may increase the codebook size, and may utilize more bits to report one column from the matrix. Described herein may be a WTRU that may utilize different (Oi)~ and (O2)~ values to determine the precoders. In examples, the WTRU may reduce the overhead, and / or increase the beam resolution as determined by the WTRU.

[0190] In examples, a WTRU may perform channel measurements (e.g., based on DL RS). The WTRU may be triggered to indicate parameters that the WTRU utilized to generate the codebook as a function of the measurements, and / or as a function of fields from a scheduling grant. The WTRU may determine that the RRC configured parameters may not be optimal. The WTRU may provide a list of new parameters to indicate that the reported CSI may be determined as a function of the list of new parameters. A WTRU may be configured with a trigger such that the WTRU may transmit the new parameter list, for example, if the trigger conditions are satisfied (e.g., measurement is above a threshold).

[0191] In examples, a WTRU may trigger based on DL RS signal quality (e.g., RSRP, RSSI, SINR). A WTRU may select Oi and O2 values as a function of the signal quality above a threshold.

[0192] In examples, a WTRU may trigger based on doppler measurement. A WTRU may select Oi and O2 values as a function of the Doppler measurement above a threshold.

[0193] In examples, a WTRU may trigger based on grant parameters. A WTRU may select O1 and O2 values as a function of the beta values for the UCI part 1 and part 2 payload carried by PUSCH. A WTRU may select O1 and O2 values as a function of the DMRS configuration indicated by a DCI. A WTRU may select O1 and O2 values as a function of the number of layers (e.g., smaller O1 and O2 for larger number of layers), and / or the MCS (larger O1 and O2 for ranks with higher MCS). A WTRU may select O1 and O2 values as a function of the number of reported PMIs per sub-band. A WTRU may select O1 and O2 values as a function of the number of TRPs scheduled to transmit the PDSCH.

[0194] In examples, a WTRU may trigger based on omission / dropping rules. A WTRU may select O1 and O2 values as a function of the omission / dropping rules (e.g., if the payload with RRC configured parameters is above a threshold and requires dropping some contents, the WTRU may adjust the O1 and O2 values such that the payload may be reduced and no content may be dropped).

[0195] In examples, a WTRU may trigger based on BLER target. A WTRU may select O1 and O2 values to achieve a target BLER on the PDSCH reception.

[0196] In examples, a WTRU may trigger based on WTRU location. A WTRU may select O1 and O2 values as a function of the WTRU location (e.g., absolute location, and / or relative location to the network).

[0197] In examples, a WTRU may trigger based on number of TRPs in the CSI. A WTRU may select O1 and O2 values as a function of the number of TRPs in the CSI report (e.g., for NC-JT or C-JT CSI reporting, a WTRU may report a CSI for N_TRPs = 1...4 for a WTRU and / or network determined number N_TRP) .

[0198] In examples, the WTRU may determine a first codebook using the configured (Oi)~ and (O2)~ oversampling values. The WTRU may determine a second codebook by adjusting the configured (Oi)~ and (O2)~ oversampling values to new oversampling values, O1 and O2. The WTRU may be configured with a CSI reporting configuration for reporting the precoders. The WTRU’s CSI report may comprise the PMI determined from (Oi)~ and (62)", from O1 and O2, and / or both. The WTRU’s CSI report may comprise an indication of the O1 and O2 values used in the second codebook (e.g., explicit O1 and O2 values, and / or a pair of O1 and O2 from a preconfigured table of O1 and O2 values).

[0199] Alternatively, or additionally, the WTRU may transmit an UL MAC-CE to request a new codebook configuration. The MAC-CE may comprise the new O1 and O2 values and / or other parameters for the new codebook configuration (e.g., codebook Type I, Type II, and / or other variants). The network may trigger an AP-CSI and / or SP-CSI request (e.g., after reception of the MAC-CE). The triggering command for the AP-CSI (e.g., DCI and / or MAC-CE) may comprise a new field to indicate to the WTRU whether to use the RRC configured (0i)~ and (O2)~ values, and / or the WTRU-determined Oi and O2 values. The RRC configured (Oi)~ and (O2)~ values may be indicated using the new field from a set of configured (Oi)~ and (t )" value pairs determined by the network. For example, the AP-CSI may indicate for the values of (Oi)~ -1 and (O2) =1 ,Solutions described herein may not be limited to indicating the oversampling values. In examples, other codebook parameters may be dynamically indicated. For example, codebook type, number of antenna ports, and / or number of antenna port groups. In examples, the trigger may comprise fields to indicate to report CSI for Type I and / or Type II, and may be measured over a subset of the N configured ports.

[0200] WTRU CSI quantization may be described herein. A WTRU may be dynamically and / or semi- statically configured (e.g., by RRC, MAC-CE, and / or DCI) for channel state information (CSI) reporting (e.g., PMI reporting based on one or more list(s) of PMIs, set(s) of PMI(s) and / or codebook(s) of PMI(s)). A WTRU may be dynamically and / or semi-statically configured (e.g., via RRC, MAC-CE and / or DCI) for one or more CSI related rule(s). For example, amplitude_rule_1 and / or amplitude_rule_2 for amplitude quantization, and / or phase_rule_1 and / or phase_rule_2 for phase quantization of a beam-scaling coefficient, beam amplitude level, beam strength, channel gain, Doppler, and / or time-domain-channel- properties (TDCP), respectively. One or more CSI related rule(s) may be configured per spatial domain, time-domain, and / or frequency domain. For example, port 1 - 10 orpolarization(s) 1 - 10 and / or slot 1 - 10 may be configured with one or more CSI related rule(s). Port 1 - 20 may be configured with set(s) (e.g., different sets) of CSI related rule(s), wherein port 1 - port 10 and port 10 - port 20 may have one or more common CSI related rule(s).

[0201] A WTRU may determine a PMI from a codebook, for example, from a codebook with adjusted DFT oversampling O1 and O2 values and / or a from a codebook with a configured (Oi)~ and (O2)~ DFT oversampling values. A WTRU may determine beam-scaling coefficient(s) for one or more beam(s) of the determined PMI. The beam-scaling coefficients may be determined per frequency-unit (e.g., per sub-band), per antenna element (e.g., per polarization if a gNB utilizes dual-polarized antennas), and / or per time-unit, (e.g., per slot).

[0202] A WTRU may determine one or more CSI related rule(s) in one or more time, frequency, and / or spatial units. In examples, a WTRU may determine amplitude_rule_1 for sub-bands 1 - 10 and amplitude_rule_2 for sub-bands 10 - 20. A WTRU may determine phase_rule_1 for slot 1 - 10 and phase_rule_2 for slots 10 - 20. A WTRU may determine phase_rule_1 for vertical polarizations andphase_rule_2 for horizontal polarizations in a dual-polarized antenna system. A WTRU may determine amplitude_rule_1 for beams 1 - 3 and amplitude_rule_2 for beams 4-6.

[0203] Quantization rule for beam-scaling amplitudes may be described herein. In examples, a WTRU may determine a quantization rule, one or more parameter(s) of a quantization rule, a quantization table out of the configured quantization rules, parameters of a quantization rule, and / or quantization tables for quantizing one or more amplitude(s) of the beam-scaling coefficient(s) based on at least one factor.

[0204] A WTRU may determine a quantization rule based on the strength of the determined nonquantized beam-scaling coefficients. In examples, a WTRU may determine parameters(s) of a quantization rule 1 - 2(-w+c / lswith N = 2Qand q = 1 ••• 2Qfor quantizing beam-scaling amplitude coefficients based on the amplitude and / or strength of the determined non-quantized beam-scaling coefficients. In examples, a WTRU may determine a larger value of s out of the configured value(s) of s when the amplitude level of the determined non-quantized beam-scaling coefficients is larger, and / or a smaller value of s when the when the amplitude level of the determined non-quantized beam-scaling coefficients is smaller. In examples, a WTRU may determine a quantization rule and / or a quantization table coarser around higher amplitude levels (e.g., coarser around 1 and denser around lower amplitude levels, denser around 0 when the strength and / or amplitude of the determined non-quantized beam-scaling coefficients is lower). In examples, a WTRU may determine a quantization rule and / or a quantization table coarser around lower amplitude levels (e.g., coarser around 0 and denser around higher amplitude levels, denser around 1 when the strength and / or amplitude of the determined non-quantized beam-scaling coefficients is higher).

[0205] A WTRU may report an index of a quantization table (e.g., table 1) parameters of the quantization scheme (e.g., maximum and / or minimum amplitude and / or difference between the maximum and minimum amplitude coefficient), resolution of the quantization scheme (e.g., the number of amplitude points in the quantization scheme and / or the parameter Q), and / or the density of a quantization scheme around the maximum and / or minimum amplitude coefficient (e.g., the parameter(s)) in a CSI report. In examples, a WTRU may report details of the quantization scheme with a higher priority as compared to the amplitude coefficients. In examples, a WTRU may report details of the determined quantization scheme in a higher priority portion of the CSI report as compared to the quantized amplitude coefficients. A WTRU may report details of the determined quantization scheme (e.g., in part 2 group 0) and / or the quantized amplitude coefficients (e.g., in part 2 group 1) in a CSI report.

[0206] Quantization rule(s) for beam-scaling phase may be described herein. In examples, a WTRU may determine a quantization rule and / or one or more parameter(s) of a quantization rule and / or a quantizationtable out of the configured quantization rules, parameters of a quantization rule, quantization tables for quantizing one or more phase(s) of the beam-scaling coefficient(s) based on at least one factor.

[0207] A WTRU may determine a quantization rule based on the phase discrepancy of the determined non-quantized beam-scaling coefficients.

[0208] A WTRU may determine a maximum and / or a minimum phase(s) of the determined non-quantized beam scaling coefficients. A WTRU may determine a quantization scheme based on the phase difference between the determined maximum and minimum phase difference.

[0209] In examples, a WTRU may determine a quadrature phase shift keying (QPSK) based phase quantization scheme, for example, if the determined phases are uniformly distributed between 0 and 360 degrees. In examples, if the determined minimum phase is 0 degree and the maximum phase is 90 degrees, a WTRU may determine a quantization scheme with phase range of 0-90 degree for quantizing the phases of the beam coefficients. In examples, a WTRU may determine the resolution and / or the number of phase points in the quantization scheme based on the determined maximum and minimum phase of the coefficients.

[0210] A WTRU may report the index of a quantization table (e.g., table 1 ) parameters of the quantization scheme (e.g., maximum and / or minimum phase and / or a difference between the maximum and minimum phase), and / or resolution of the quantization scheme (e.g., the number of phase points in the quantization scheme.) in a CSI report. A WTRU may report details of the quantization scheme with a higher priority as compared to the phase coefficients.

[0211] In examples, a WTRU may report details of the determined quantization scheme in a higher priority portion of the CSI report as compared to the quantized phase coefficients. A WTRU may report details of the determined quantization scheme (e.g., in part 2 group 0) and the quantized phase coefficients (e.g., in the part 2 group 1) in the CSI report.

[0212] Actual and / or differential quantization of the beam-scaling coefficients may be described herein. A WTRU may determine a quantization type based on the strength of the determined non-quantized beamscaling coefficients and / or the non-quantized beam-scaling phase. A quantization type may be actual and / or differential. Actual quantization of beam-scaling coefficients may comprise each coefficient being independently quantized according to a rule. Differential quantization may comprise each coefficient being quantized according to a reference coefficient (e.g., according to a maximum coefficient). A WTRU may determine a quantization type based on at least one factor.

[0213] A WTRU may determine a quantization type (e.g., actual and / or differential) based on the difference between the maximum and the minimum coefficient values (e.g., based on the difference maximum - minimum of the non-quantized coefficient value) and / or variance of the non-quantized coefficient values. In examples, when the difference between the maximum and the minimum coefficient value is smaller than or equal to a configured and / or indicated threshold, a WTRU may determine the quantization type as differential. In examples, when the difference between the maximum and the minimum coefficient value is greater than a configured and / or indicated threshold, a WTRU may determine the quantization type as differential.

[0214] A WTRU may determine the range of the non-quantized coefficient values when the quantization type is determined to be differential. In examples, a WTRU may determine the non-quantized coefficient values of the maximum and / or minimum coefficient values. A WTRU may report quantized version of the maximum and minimum coefficient values in a CSI report.

[0215] A WTRU may determine a maximum, minimum, median, and / or average non-quantized and / or quantized value of the beam-scaling coefficients as the reference for quantizing the remaining coefficients. In examples, a WTRU may determine the maximum quantized and / or non-quantized coefficient as the reference amplitude. A WTRU may report index(es) of the reference amplitude (e.g., spatial, frequency, and / or time index of the reference amplitude). In examples, a WTRU may report an index of a beam, antenna port, sub-band and / or slot and a quantized coefficient value as the reference coefficient.

[0216] A WTRU may quantize coefficients (e.g., remaining coefficients) based on a reference coefficient. In examples, a WTRU may quantize a coefficient (e.g., A_coefficient) based on the reference (e.g., A_reference) as A_coefficient = A_reference + offset or A_coefficient = A_reference - offset. The offset may be determined based on the difference A_reference - A_coefficient. In examples, the resolution of the offset may be determined based on the difference between the maximum and minimum coefficients (e.g., maximum-minimum).

[0217] A WTRU may report the reference coefficient, offset, and / or the remaining quantized coefficients in a CSI report.

Claims

CLAIMS:

1. A wireless transmit / recei ve unit (WTRU) comprising: a processor configured to: receive a CSI resource configuration, the CSI resource configuration comprising information related to a grid-of-beams (GoB) that comprises a plurality of beams, an indication to partition the GoB into sub-grids, an indication of an initial set of candidate beams, and a selection criteria; determine one or more beams of the initial set of candidate beams for selection based on the selection criteria; and send a precoding matrix indicator (PMI) based on the one or more beams of the initial set of candidate beams that were selected.

2. The WTRU of claim 1 , wherein the processor is configured to: send a CSI report message comprising information related to one or more beams of the initial set of candidate beams that were not selected.

3. The WTRU of claim 1 , wherein the processor is configured to select beams from the initial set of candidate beams based on amplitude levels or a window of amplitude levels for beams in one or more of the sub-grids of the GoB and a threshold amount.

4. The WTRU of claim 1 , wherein the selection criteria comprises one or more of a maximum amplitude level, a minimum amplitude level, or an amplitude level window.

5. The WTRU of claim 1 , wherein the processor is configured to receive a class indication; wherein the class indication comprises a first class indication that indicates that the one or more beams of the initial set of candidate beams are selected based on a maximum amplitude level, a minimum amplitude level, or an amplitude level window; or wherein the class information comprises a second class indication that indicates that processor should exclude one or more beams that are not part of the initial set of candidate beams.

6. The WTRU of claim 1 , wherein the processor is configured to receive an indication of a reference amplitude for each of the one or more indicated sub-grids.

7. The WTRU of claim 6, wherein the processor is configured to select one or more beams from the one or more indicated sub-grids based on the indicated reference amplitude for each of the one or more indicated sub-grids being greater than a threshold amount.

8. The WTRU of claim 1, wherein the processor is configured to determine quantized values for one or more beams in the initial set of candidate beams, and to identify beams for selection based on a comparison of the quantized values for the one or more beams to the selection criteria.

9. The WTRU of claim 1 , wherein the processor is configured to: determine a strongest beam from the plurality of beams in the GoB based on a comparison of amplitude levels for each of the plurality of beams; and determine a relative amplitude level for each of the plurality of beams not determined to be the strongest beam using an amplitude level of the strongest beam as a scaling reference.

10. The WTRU of claim 9, wherein the processor is configured to select beams from the initial set of candidate beams based on the determined relative amplitude level for each of the plurality of beams of the GoB and a threshold amount.

11. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving a CSI resource configuration, the CSI resource configuration comprising information related to a grid-of-beams (GoB) that comprises a plurality of beams, an indication to partition the GoB into sub-grids, an indication of an initial set of candidate beams, and a selection criteria; determining one or more beams of the initial set of candidate beams for selection based on the selection criteria; and sending a precoding matrix indicator (PMI) based on the one or more beams of the initial set of candidate beams that were selected.

12. The method of claim 11 , further comprising sending a CSI report message comprising information related to one or more beams of the initial set of candidate beams that were not selected.

13. The method of claim 11 , further comprising selecting beams from the initial set of candidate beams based on amplitude levels or a window of amplitude levels for beams in one or more of the sub-grids of the GoB and a threshold amount.

14. The method of claim 11 , wherein the selection criteria comprises one or more of a maximum amplitude level, a minimum amplitude level, or an amplitude level window.

15. The method of claim 11 , further comprising receiving a class indication; wherein the class indication comprises a first class indication that indicates that the one or more beams of the initial set of candidate beams are selected based on a maximum amplitude level, a minimum amplitude level, or an amplitude level window; or wherein the class information comprises a second class indication that indicates that processor should exclude one or more beams that are not part of the initial set of candidate beams.

16. The method of claim 11 , further comprising receiving an indication of a reference amplitude for each of the one or more indicated sub-grids.

17. The method of claim 16, further comprising selecting one or more beams from the one or more indicated sub-grids based on the reference amplitude for each of the one or more indicated sub-grids being greater than a threshold amount.

18. The method of claim 11, further comprising determining quantized values for one or more beams in the initial set of candidate beams, and identifying beams for selection based on a comparison of the quantized values for the one or more beams to the selection criteria.

19. The method of claim 11 , further comprising: determining a strongest beam from the plurality of beams in the GoB based on a comparison of amplitude levels for each of the plurality of beams; anddetermining a relative amplitude level for each of the plurality of beams not determined to be the strongest beam using an amplitude level of the strongest beam as a scaling reference.

20. The method of claim 19, further comprising selecting beams from the initial set of candidate beams based on the determined relative amplitude level for each of the plurality of beams of the GoB and a threshold amount.

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