Process for hybrid beamforming in wireless systems

Abstract

Systems and methods for hybrid beamforming (HBF) in a wireless environment implemented in a wireless transmit / receive unit (WTRU) are disclosed. The WTRU may be configured to receive an indication associated with enabling an HBF type recommendation and / or receive a configuration associated with HBF processing. The WTRU may determine a channel matrix associated with a sub-band, determine one or more feedback overhead information, and / or determine one or more HBF pre-decoders. The WTRU may determine a preferred HBF type based on a set of pre-configured parameters associated with the configuration related to HBF processing, and / or determine a set of Vandermonde phases based on the set of pre-configured parameters associated with the configuration related to HBF processing. The WTRU may report HBF information and / or angles associated with quantization information to a base station. The WTRU may receive a second configuration.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 331,026, filed on April 14, 2022, and U.S. Provisional Application No. 63 / 488,265, filed on March 3, 2023, the entire contents of which are incorporated herein by reference. Background Art

[0003] Various aspects of the present disclosure relate to beamforming, and more particularly to a process for hybrid beamforming for a wireless transmit / receive unit (WTRU) in a wireless system.

[0004] Wireless access systems have been widely deployed to provide various types of communication services such as voice or data. A wireless access system may be a multiple-access system that supports communication for multiple users by sharing available system resources (eg, bandwidth, transmit power, etc.) among the multiple users.

[0005] For example, the multiple access system may include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, and a single carrier frequency division multiple access (SC-FDMA) system. Summary of the invention

[0006] Example embodiments in the present disclosure relate to a wireless transmit / receive unit (WTRU) that may be configured to receive an indication associated with enabling a hybrid beamforming (HBF) type recommendation and / or receive a configuration related to HBF processing. In some examples, the WTRU may be configured to determine a channel matrix associated with a sub-band. Alternatively or additionally, the WTRU may be configured to determine one or more feedback overhead information. Alternatively or additionally, the WTRU may be configured to determine one or more hybrid beamforming (HBF) pre-decoders. The HBF pre-decoder may be associated with one or more feedback overhead information.

[0007] The WTRU may be configured to determine a preferred HBF type, for example, based on a set of preconfigured parameters. The set of preconfigured parameters may be associated with configurations related to HBF processing. The WTRU may be configured to determine a Vandermonde phase set, for example, based on a set of preconfigured parameters.

[0008] In one example, the WTRU may be configured to report HBF information and / or report angles associated with the quantized information.The WTRU may report the HBF information and / or the angles associated with the quantized information to the base station.

[0009] The WTRU may determine at least one constraint related to processing performance or feedback overhead associated with each of a plurality of hybrid beamforming (HBF) types. The WTRU may be configured to report HBF information related to a preferred HBF type and associated parameters among a plurality of HBF types to a base station based on a configuration related to HBF processing and at least one constraint related to processing performance or feedback overhead associated with each of the plurality of HBF types. The HBF information may indicate at least one of a preferred HBF type, a HBF predecoder associated with the preferred HBF type, or an effective rank associated with the preferred HBF type. The WTRU may be configured to determine a channel matrix associated with a subband, derive one or more HBF predecoders using the channel matrix, and / or determine the preferred HBF type based on a set of preconfigured parameters associated with the configuration related to the HBF processing. The HBF predecoder may be associated with at least one constraint related to processing performance or feedback overhead. One of the HBF types may include a Vandermonde structure. The configuration may include a first configuration. The preferred HBF type may include a first preferred HBF type. The WTRU may be configured to: receive a second configuration related to hybrid beamforming (HBF) processing; and / or switch from a first preferred HBF type among multiple HBF types to a second preferred HBF type based on a second configuration related to BHF and at least one constraint related to processing performance or feedback overhead associated with each of the multiple HBF types; and / or report second HBF information related to a second preferred HBF type among multiple HBF types and associated parameters to a base station. The second HBF information may indicate at least one of a second preferred HBF type, a HBF pre-decoder associated with the second preferred HBF type, or an effective rank associated with the second preferred HBF type. Reporting to the base station may include reporting a Vandermonde-based codebook derived from one or more measurements performed by the WTRU. Switching from a first preferred HBF type among multiple HBF types to a second preferred HBF type may be based on a triggering event. The triggering event may include satisfying one or more of a performance threshold, a threshold associated with a monitoring value, and a pre-configured condition. The WTRU may be configured to receive a configuration related to HBF processing. The WTRU may be configured to derive a configuration related to HBF processing, for example, based on one or more measurements made by the WTRU. The WTRU may be configured to derive one or more HBF pre-decoders using a channel matrix. The HBF pre-decoder may be associated with at least one constraint related to processing performance or feedback overhead. The constraint may include a measurement angle. The WTRU may receive a second configuration. The second configuration may be received from a base station. The second configuration may include one or more of a preferred HBF type, a HBF pre-decoder associated with the preferred HBF type, an effective rank associated with the preferred HBF type, a second HBF type, a HBF pre-decoder associated with the second HBF type, or an effective rank associated with the second HBF type.The second configuration may be based on the HBF information. For example, the second configuration may be based on the HBF information related to a preferred HBF type among a plurality of HBF types and associated parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented.

[0011] Figure 1B is an example of a method that can be used according to an embodiment of the present invention. Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the illustrated communication system.

[0012] Figure 1C is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of an example Radio Access Network (RAN) and an example Core Network (CN) for use within the illustrated communication system.

[0013] Figure 1D is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of yet another example RAN and yet another example CN for use within the illustrated communication system.

[0014] Figure 2 is a diagram illustrating an example of a channel state information (CSI) measurement setting.

[0015] Figure 3 is a diagram illustrating example codebook-based precoding using feedback information.

[0016] Figure 4 is a table showing an example of a codebook for 2Tx.

[0017] Figure 5 is a block diagram illustrating an example of a hybrid beamforming architecture.

[0018] Figure 6 is a graph illustrating an example of bit error rate (BER) performance of one or more hybrid beamforming methods.

[0019] Figure 7 is a chart illustrating an example of the running time of one or more hybrid beamforming methods.

[0020] Figure 8 is a table showing an example of feedback overhead.

[0021] Fig. 9 is a diagram illustrating an example Hybrid Beamforming (HBF) process for determining a preferred HBF type.

[0022] Fig.10is an example table illustrating table-based quantization that may be used for one of the predefined quantization types.

[0023] Fig.11 is a diagram illustrating formula-based quantization.

[0024] Fig.12 is a table showing an example of relative quantization based on a formula.

[0025] Fig.13 is a diagram illustrating an example process for an example adaptive Vandermonde-based codebook design. DETAILED DESCRIPTION

[0026] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0027] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood 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 “STA”) may be configured to send and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0028] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is 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 Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, 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.

[0029] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrums. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver 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 send and / or receive signals in a desired spatial direction.

[0030] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0031] More specifically, as noted above, the communication 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, etc. 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 use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. 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).

[0032] 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) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0033] 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).

[0034] 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 together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0035] 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, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0036] Figure 1AThe base station 114b in the may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, 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 a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0037] 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 different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although not described in detail in the text, the CN 106 / 115 may be 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 different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Figure 1A Although not shown in the figure, 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 utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0038] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides 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), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication 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.

[0039] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication 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 via different wireless links). Figure 1A The illustrated WTRU 102c 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.

[0040] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0041] 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 associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, 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. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0042] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, IR, UV or visible light signals. In another embodiment, the send / receive element 122 may be configured to send and / or receive both RF signals and optical signals. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0043] Although the transmit / receive element 122 Figure 1B 1 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.

[0044] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0045] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a 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 a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0046] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0047] 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 from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0048] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: 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.

[0049] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for 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 for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0050] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with 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.

[0051] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-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 evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0052] Each of the evolved Node 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 UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0053] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0054] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 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, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0055] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an 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 the user plane during inter-evolved Node-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0056] 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.

[0057] 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 be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0058] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0059] In a representative embodiment, the other network 112 may be a WLAN.

[0060] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STA) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and leading to the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be transmitted to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the destination STA (e.g., directly between them) using a direct link establishment (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0061] When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. In the case where the primary channel is listened / detected and / or determined to be busy by a specific STA, the specific STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0062] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0063] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and data can be sent by the transmitter STA. At the receiver of the receiver STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0064] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0065] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum 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 (which supports the minimum bandwidth operating mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC type devices) that support (e.g., only support) 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only the 1MHz operating mode) is sending to the AP, the entire available frequency band may be considered busy even if most of the frequency bands remain idle and may be available.

[0066] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0067] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ 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.

[0068] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of 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, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send 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, gNB 180a may transmit multiple component carriers to 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, 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).

[0069] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or varying absolute time lengths over time).

[0070] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0071] 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 UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0072] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0073] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 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 mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0074] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure the traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0075] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the 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, etc.

[0076] 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 acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0077] Given that Figures 1A to 1D as well as Figures 1A to 1D , one or more or all of the functions described herein for one or more of the following may be performed by one or more simulation devices (not shown): WTRU 102a-102d, base station 114a-114b, evolved Node B 160a-160c, MME 162, SGW 164, PGW 166, gNB 180a-180c, AMF 182a-182ab, UPF 184a-184b, SMF 183a-183b, DN 185a-185b and / or any other device described herein. The simulation device may be one or more devices configured to mimic one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0078] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions 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. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0079] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0080] When a base station (e.g., a gNB) and a WTRU are communicating, the device may implement one or more beamforming processes to focus a wireless signal sent from a transmitter in a direction toward a receiver or receiver antenna. Beamforming may be used to improve signal-to-noise ratio, mitigate high propagation path losses, reduce interference, and / or focus signal transmission to a desired location. As further described herein, a base station and / or a WTRU may include multiple transmit antennas at a transmitter and / or multiple receive antennas at a receiver, which may be implemented during a beamforming process to focus signal transmission. For example, a transmitter and / or a receiver may include an antenna array or subarray. A transmitter may use multiple antennas of an array or subarray to transmit and direct the same signal toward a receiver.

[0081] Analog beamforming involves a change in the phase of the signal at the transmitter, which can use a single RF chain (e.g., including RF processing and ADC / DAC conversion) for an antenna array (e.g., a phased antenna array). Each antenna element can be connected to a phase shifter that can be used to set the weights T for beamforming and beam steering.

[0082] Digital beamforming may have one RF chain (e.g., including RF processing and ADC / DAC conversion) for each antenna element of the antenna array. Thus, the signal at each antenna element may be independently controlled and / or processed in both phase and amplitude, e.g., to optimize system capacity.

[0083] Hybrid beamforming (HBF) may involve aspects of analog beamforming and / or digital beamforming. For example, a hybrid beamforming process may use antenna subarrays to transmit and / or receive signals. One or more data streams may be pre-coded (e.g., as in digital beamforming). The pre-coded data streams may be transmitted to an analog beamformer (e.g., a subarray). Each subarray stream may be phase shifted to transmit a beam from each subarray. Each transmitted subarray beam may be directed to a receiver.

[0084] Millimeter wave (mmWave) systems may use (e.g., highly) directional systems to mitigate the high path losses associated with higher frequency bands. For example, due to the increased power consumption associated with the RF chains, all-digital beamforming methods may not be practical for large antenna array (e.g., transmit / receive elements 122) systems. To mitigate power consumption, a hybrid beamforming (HBF) architecture (e.g., which may use fewer RF chains than the number of antennas) may be used for mmWave multiple-input / multiple-output (MIMO) systems. In one example, the HBF predecoder may be composed of a digital predecoder applied in the baseband and / or an analog beamformer applied at the RF. In one example, finding an analog beamformer (e.g., finding an optimal analog beamformer) may be a high latency and / or high overhead process (e.g., due to the large search space).

[0085] Systems and methods for HBF in wireless systems are described herein. When performing communications using HBF, the gNB and WTRU may utilize (e.g., different) HBF types. For example, the HBF type may include one or more of a U-unit magnitude HBF type, a C-codebook-based HBF type, and / or a V-Vandermonde constrained HBF type. In some examples, the beamforming solution may use (e.g., any) predefined codebook and / or phase shifter (e.g., unit magnitude) for analog beamforming weights. The codebook-based selection of analog beamforming weights may, for example, tend to have low feedback overhead and / or may have suboptimal performance. Analog beamforming based on unit magnitude may have better performance and / or may have increased feedback overhead. For example, for a HBF system, a HBF pre-decoder (e.g., for Tx) and / or a combiner (e.g., for Rx) may be determined to reduce feedback overhead (e.g., CSI) (e.g., while maintaining target performance). For example, the analog pre-decoder may be constrained to a Vandermonde structure to reduce CSI feedback overhead. The WTRU may use methods to determine the preferred HBF type and / or report to the gNB.

[0086] The constraints may include one or more of payload size (e.g., allocated payload size), received signal-to-noise ratio (SNR), effective rank, one or more channel conditions, physical downlink shared channel (PDSCH) performance, and / or any (e.g., weighted) combination of these. Alternatively or additionally, the constraints may include one or more of channel state information (CSI), block error rate (BLER) performance, (e.g., effective) resolution, reference signal received power (RSRP), delay spread, carrier frequency, modulation, subcarrier spacing, number of transmit and / or receive antennas, wavelength, angle, absolute angle, relative angle, center angle, number of layers, pre-coding resource group (PRG) size, and WTRU speed.

[0087] The WTRU may perform a process to determine one or more preferred HBF types and / or one or more HBF pre-decoders. In one example, the WTRU may receive an indication and / or activation for enabling a HBF type recommendation. For example, a higher layer parameter (HBF type-recommendation) may be set to 1, which may indicate that the WTRU may determine and / or report a preferred HBF type and / or associated pre-decoding weight. The WTRU may receive configurations related to HBF processing, such as a payload size (B), number of layers, pre-decoding resource block group (PRG) size, HBF type, effective rank, etc. for reporting HBF-related information. In another example, the WTRU may estimate the channel matrix H[k]. The channel matrix H[k] may be associated with the kth sub-band, where k=1,…,K. In one example, the WTRU may derive an analog and / or hybrid pre-decoder associated with the configured HBF type (e.g., U-unit magnitude, C-codebook-based, V-Vandermonde constraint, etc.). The WTRU may determine the preferred HBF type based on a set of preconfigured and / or measured parameters (e.g., allocated payload size, received signal-to-noise ratio (SNR), effective rank, channel conditions, physical downlink shared channel (PDSCH) performance, and / or any weighted combination of these parameters and / or other similar parameters). The WTRU may report (e.g., implicitly or explicitly) the selected HBF type and / or the associated hybrid precoder (e.g., F RF 、F BB ) and / or the effective ranks associated with different HBF types.

[0088] The WTRU may perform a process for adaptive Vandermonde-based codebook design. The WTRU may receive one or more configurations related to HBF Type V processing, including, for example, relative angle, required resolution, quantization method, payload size for reporting Type V weights, etc. The WTRU may estimate the channel matrix H[k] associated with the kth subband, where k=1,…,K. The WTRU may derive an analog and / or hybrid pre-decoder associated with HBF Type V.

[0089] The WTRU may determine a set of Vandermonde phases, for example, based on an allocated payload size. In one example, the WTRU may obtain a phase subset by determining a center angle and / or a relative angle based on channel measurements (e.g., Doppler, coherence time, etc.). In another example, the WTRU may obtain a set of phases based on one or more angle of arrival (AoA) measurements, one or more positioning related measurements (e.g., PRS), etc. The WTRU may report absolute and / or relative angles associated with a particular quantization method (e.g., table, formula, etc.). For example, the WTRU may report relative angles and / or quantization steps according to preconfigured values. The WTRU may determine a preferred HBF from a plurality of Vandermonde types, for example, based on one or more parameters and / or measurements. For example, the WTRU may determine a preferred HBF from a plurality of Vandermonde types based on measured angles.

[0090] The channel state information (CSI) may include one or more of: a channel quality index (CQI), a rank indicator (RI), a precoding matrix index (PMI), an L1 channel measurement (e.g., a reference signal received power (RSRP) such as L1-RSRP, a signal to interference and noise ratio (SINR), etc.), a CSI-RS resource indicator (CRI), a SS / PBCH block resource indicator (SSBRI), a layer indicator (LI), and / or any other measurement quantity measured by the WTRU from a configured reference signal (e.g., CSI-RS, SS / PBCH block, and / or any other reference signal). The WTRU may be configured to report CSI, for example, via an uplink control channel on the PUCCH and / or upon gNB request on a UL physical uplink shared channel (PUSCH) grant. In one example (e.g., depending on the configuration), the CSI-RS may cover the entire bandwidth of a bandwidth part (BWP) or only a small portion of the bandwidth. Within the CSI-RS bandwidth, the CSI-RS may be configured in every PRB or every other PRB. CSI-RS resources may be configured as one or more of periodic, semi-persistent, or aperiodic (e.g., in the time domain). Semi-persistent CSI-RS may be similar to periodic CSI-RS, except that, for example, resources may be activated (deactivated) by a MAC control element. The WTRU may report relevant measurements when the resource is activated. The WTRU may be triggered to report CSI-RS measured on the PUSCH through a request in the DCI, for example, for aperiodic CSI-RS. Periodic reports may be carried on the PUCCH. For example, semi-persistent reports may be carried on the PUCCH and / or PUSCH (e.g., either one). In one example, the reported CSI may be used by the scheduler to allocate optimal resource blocks, for example, based on one or more of the following: time-frequency selectivity of the channel, determining the precoding matrix, beam, transmission mode, and / or selecting an appropriate MCS. In one example, the reliability, accuracy, and / or timeliness of the WTRU CSI report may be critical to meeting URLLC service requirements.

[0091] The WTRU may be configured with a CSI measurement setup. The CSI measurement setup may include one or more CSI reporting setups, resource setups, and / or links between one or more CSI reporting setups and one or more resource setups. Figure 2An example system 200 is shown for configuration of CSI report settings 202, 204, resource settings 214, 216, 218, and links 206, 208, 210, 212. For example, there may be multiple CSI report settings, including, for example, CSI report setting 0 202 and / or CSI report setting 1 204. For example, in a CSI measurement setting, one or more configuration parameters may be provided. The example configuration may include one or more of: N≥1 CSI report settings 202, 204, M≥1 resource settings 214, 216, 218, and a CSI measurement setting 220 that may link the N CSI report settings 202, 204 with the M resource settings 214, 216, 218. In some examples, there may be one or more of: a link 206 (e.g., link 0) between CSI report setting 0 202 and resource setting 0 214, a link 208 (e.g., link 1) between CSI report setting 0 202 and resource setting 1 216, a link 210 (e.g., link 2) between CSI report setting 0 202 and resource setting 2 218, and / or a link 212 (e.g., link 3) between CSI report setting 1 204 and resource setting 0 214. For example, a CSI report setting may include one or more settings. A CSI setting may include a time domain behavior, which may be aperiodic and / or periodic / semi-persistent. At least for PMI and / or CQI, a setting may include frequency granularity. A setting may include a CSI report type (e.g., PMI, CQI, RI, CRI, etc.). For example, a setting may include: if PMI is reported, a PMI type (type I or II) and / or a codebook configuration. A resource setting may include one or more settings (e.g., multiple settings). Resource settings may include time domain behaviors, such as non-periodic and / or periodic / semi-persistent. For example, resource settings may include RS types (e.g., for channel measurement or interference measurement). Resource settings may include S≥1 resource sets, and / or each resource set may include Ks resources. The CSI measurement setting 220 may include one or more settings (e.g., multiple settings). For example, the CSI measurement setting 220 may include a CSI report setting. In one example, the CSI measurement setting may include a resource setting. For CQI, the CSI measurement setting 220 may include a reference transmission scheme setting. One or more frequency granularities for CSI reporting for component carriers may be supported. The frequency granularity may be wideband CSI. For example, the frequency granularity may be partial-band CSI. For example, the frequency granularity may be sub-band CSI.

[0092] Figure 3An example system 300 is illustrated that illustrates the basic concept of codebook-based precoding with feedback information. The system 300 may include a transmitter 302 capable of performing MIMO communication via multiple (e.g., Nt) transmit antennas. The transmitter 302 may transmit one or more streams (e.g., Mt data streams or layers x1 to x2) of modulation symbols. Mt ), where the number of streams Mt may be less than Nt. The symbols x1 to x Mt It can be generated by baseband data channel processing and / or can be applied at the input of the pre-decoder for transmission via Nt transmit antennas. The signal transmitted by the Nt transmit antennas is from z1 to z Nt System 300 may include a receiver 304 capable of receiving MIMO communications via multiple (eg, Nr) receive antennas. Signals received at the antenna inputs are denoted by r1 to r Nr The receiver 304 may process the signals received at the Nr antennas to recover the transmitted stream (eg, data stream). to For further (eg, baseband) processing at a receiving device, the number of transmitted streams Mt may be less than or equal to Nr.

[0093] For a closed-loop MIMO system, the receiver 304 may provide channel state feedback information 306 to the transmitter 302; for example, for codebook-based precoding. The feedback may include an index of a preferred codeword identified by the receiver (e.g., a codeword that maximizes the received signal-to-noise ratio). The codebook may include a set of vectors and / or matrices that, for example, may help maximize the orthogonality of a composite channel matrix to support multi-stream and / or multi-layer communications. The size of the vectors and / or matrices in the codebook may depend on the number of layers and / or the number of transmit antenna ports used for transmission. For example, for a 1-layer transmission using two Tx antenna ports, the precoding codebook may include a 2-dimensional vector of length 2, while for a 2-layer transmission using two Tx antenna ports, the precoding codebook may include a matrix of size 2×2. In another example, the structure of the codebook may be independent of the number of layers. For a transmitter equipped with Tx antenna ports, the precoding codebook may include a 2-dimensional vector, for example, where the number of selected vectors is equal to the number of layers. For example, one vector may be selected for a 1-layer transmission, while two vectors may be selected for a 2-layer transmission. The receiver 304 may implement a detection or estimation algorithm, such as a maximum likelihood (ML) estimation algorithm or a minimum mean square error (MMSE) estimation algorithm, to generate feedback information 306 for reporting back to the transmitter 302. For example, the receiver 304 may implement an algorithm for estimating a channel response matrix and / or an equalization algorithm. In another example, the receiver 304 may implement an algorithm for deriving an all-digital beamformer, which may be used, for example, to generate hybrid beamforming feedback information 306.

[0094] Feedback information 306 may include a precoding matrix index (PMI). The PMI may be referred to as a codeword index, for example in a codebook as shown. Figure 3 As shown, the codebook may include a set of precoding vectors / matrices for each rank and / or number of antenna ports. Each precoding vector / matrix may have its own index, for example, so that the receiver 304 can inform the transmitter 302 of the preferred precoding vector / matrix index. Compared to non-codebook-based precoding, codebook-based precoding may have degraded performance, for example, due to its limited number of precoding vectors / matrices. In some examples, an advantage of codebook-based precoding may be lower control signaling / feedback overhead.

[0095] Figure 4 Table 400 is shown illustrating an example of a codebook for 2Tx antennas. For example, a mmWave system may use a highly directional system. A highly directional system may mitigate the high path loss associated with higher frequency bands. For example, due to the increased power consumption associated with the RF chain, a fully digital beamforming approach that employs an RF chain for each antenna may not be practical for a large antenna array system. In one example, a transceiver architecture that uses fewer RF chains than the number of antennas, which may be referred to as hybrid beamforming (HBF), may be used for a mmWave MIMO system. Additionally or alternatively, a transceiver architecture that uses fewer RF chains than the number of antennas may mitigate power consumption issues, such as while providing beamforming gain to mitigate path loss.

[0096] Figure 5 A block diagram of an example system 500 of a fully connected hybrid beamforming architecture is shown. As shown in system 500, each RF chain can be connected to each antenna element 502. The HBF pre-decoder used at the transmitter 504 may include a digital F BB Pre-decoder 503 (eg, which may be applied at baseband) and / or analog F RF Beamformer 505 (which may be applied at RF, for example). Simulation F RF 505 may be selected from a predefined codebook (e.g., it may be a codebook-based HBF) and / or a phase shifter may be used (e.g., it may be a unit magnitude-based HBF). In one example, the HBF combiner used at the receiver 506 may include an analog W RF Combiner 507 (which may be an analog beamformer, for example) and / or a digital W BB Combiner 509. For example, the full channel frequency response (CFR) matrix may be used to determine the hybrid precoding and combining weights. In one example, the feedback overhead associated with reporting the estimated channel response matrix to the gNB (BS) may be large. For example, the feedback overhead associated with reporting the estimated channel response matrix to the gNB (BS) may be large for a multi-carrier massive MIMO system.

[0097] The size of the full channel response matrix can be Nr×Nt×Nc, where Nr is the number of receive antennas, Nt is the number of transmit antennas, and Nc is the number of frequency domain samples for which the CFR will be reported. In one example, when reporting with sub-band resolution (e.g., 2RBs per sub-band), there may be 26 frequency domain samples to report. For a system with 64 Tx antennas and 8 Rx antennas, the size of the full channel response matrix may be 8×64×26 complex numbers. This can scale rapidly as the number of Tx or Rx antennas increases and / or as bandwidth increases. The frequency of reporting CSI feedback may contribute to overhead.

[0098] Here, N t It can represent the number of transmitting antennas. r It can represent the number of receiving antennas. s The number of flows (eg, the number of data flows N) may be represented s ). The number of flows and layers N L They are used interchangeably herein. May indicate the number of transmit RF chains. H[k] (e.g., N r ×) may represent, for example, a complex channel matrix associated with subband k. RF (For example, ) can represent a complex analog pre-decoder. BB [k](For example, ) may represent a complex baseband (eg, digital) precoder associated with subband k. RF (For example, ) can represent a complex analog combiner. BB [k](For example, ) may represent a complex baseband (eg, digital) combiner associated with subband k. opt [k](e.g., N t ×N s ) may represent the complex optimal pre-decoder associated with sub-band k. opt [k](For example, N r ×N s ) may denote the complex optimal combiner associated with subband k.

[0099] The beamforming solution may use a predefined codebook and / or phase shifter (e.g., unit magnitude), for example, for analog beamforming weights. In one example, codebook-based selection of analog beamforming weights may have low feedback overhead and / or may have suboptimal performance. In another example, unit magnitude-based analog beamforming may have higher performance than codebook-based selection of analog beamforming weights and / or may have increased feedback overhead.

[0100] Embodiments herein may address the problem of determining a HBF predecoder and / or HBF combiner for a HBF system. For example, embodiments may address how to determine a HBF predecoder and / or HBF combiner, for example, to reduce (CSI) feedback overhead while maintaining performance. Embodiments herein may address the problem of determining information related to HBF. For example, embodiments may address how a WTRU may determine one or more preferred HBF types, and / or how a WTRU may report a preferred HBF type to a gNB. Embodiments herein may address the problem of designing an analog predecoder codebook to reduce overhead. For example, embodiments may address how a WTRU may adaptively design an analog predecoder codebook to reduce overhead while maintaining target performance.

[0101] Hybrid beamforming can be used as a pre-decoder to decompose the all-digital SVD based F opt [k], is proposed by the factorization problem, such as the hybrid pre-decoding component F RF and F BB [k], for k∈[k]. In one example, the factorization may be solved under the constraint that phase shifters may be used to model the analog pre-decoder. For example, two widely used feasibility sets may be unit modulus constraints (which may be referred to herein as HBF type U and / or type U) on the entries of each analog beamformer (e.g., Additionally or alternatively, two widely used feasibility sets may be, for example, codebook constraints (which may be referred to herein as HBF Type C and / or Type C), where, for example, each analog pre-decoder may belong to a predefined codebook known at the WTRU and / or gNB. In one example, the two feasible sets may result in an overhead-performance tradeoff. In one example, HBF Type U may have greater link performance than Type C. In one example, the communication overhead of HBF Type C may be quite low, which may, for example, make HBF Type C more suitable for limited feedback systems. Compared to Type C, the feedback overhead associated with Type U may scale linearly with the number of Tx / Rx antennas, which may, for example, prevent and / or limit the use of Type U in massive MIMO systems. As an example, the hybrid beamforming problem may be posed as in equation (1), where, for example, the feasible set The selection can be made according to Type C or Type U.

[0102]

[0103] The WTRU may report its HBF capability, for example as a field under PHY parameters in the WTRU radio access capabilities. The field may be represented as HBF-PrecodingCapability, which may be, for example, one bit. The report of the HBF capability (e.g., one bit) may indicate whether the WTRU supports hybrid pre-decoder calculations. In one embodiment, the WTRU may determine its capabilities based on one or more of the following: the number of idle CPUs, the average calculation time associated with one or more (e.g., each) types, the number of layers, the number of RF chains, the number of sub-bands, etc. In one embodiment, the WTRU may be configured to report a hybrid pre-decoder associated with a pre-configured HBF type. In one embodiment, the WTRU may be configured to directly report the optimal digital pre-decoder associated with each sub-band. In one embodiment, the WTRU may be configured to report CSI associated with different sub-bands.

[0104] In one embodiment, a configuration (e.g., HBF-ReportConfig) may be associated with a single downlink BWP (e.g., which may be indicated by a higher layer parameter BWP-Id). The configuration may include one or more of the following: HBF type, codebook configuration if the HBF type is set to type C, number of subbands, quantization parameters if the HBF type is set to type U, other HBF related parameters (e.g., effective rank indicator), HBF wideband configuration that may include parameters related to calculating analog pre-decoders, and / or HBF subband configuration, e.g., with parameters related to baseband parameter calculation. The codebook configuration (e.g., CodebookConfig) may include parameters of type C, which may include, for example, codebook subset constraints (e.g., when applicable).

[0105] The WTRU may be configured with a configuration (e.g., HBF-ReportConfig) set to None. In one example, a WTRU configured with an HBF-ReportConfig set to None may not derive and / or report any analog and / or digital precoder parameters. The WTRU may be configured to report an SVD-based digital precoder and / or estimated CSI. If the WTRU is configured with an HBF-ReportConfig in which the HBF type is set to Type C, the WTRU may report a preferred analog precoder matrix for the configured codebook and / or the WTRU may report a preferred precoder (e.g., baseband) matrix for each subband. In one example, if the WTRU is configured with an HBF-ReportConfig in which the HBF type is set to Type U, the WTRU may report a preferred analog precoder matrix (e.g., in which each element may be a unit modulus) and / or the WTRU may report a preferred precoder (e.g., baseband) matrix for each subband. In one example, if the WTRU is configured with HBF-ReportConfig where HBF-effRI is set to 1, the WTRU may report the effective rank associated with one, some, and / or all configured HBF types.

[0106] A high quality HBF pre-decoder with low feedback overhead may be determined. The analog beamformer may include a Vandermonde structure (eg, referred to herein as HBF Type V). For example, to reduce the latency associated with the analog beamformer (eg, F RF ), associated feedback and simultaneously achieving target performance, the analog beamformer can be constrained to have a Vandermonde structure (e.g., referred to herein as HBF type V). The Vandermonde feasibility set can be defined as in equation (2), for example, where φ∈-[π,π].

[0107]

[0108] The hybrid beamforming problem with Vandermonde constraints can be expressed as in equation (3).

[0109]

[0110] Finding each analog beamformer may require calculating the center angle φ, e.g., generating the entire vector. In one example, from a feedback perspective, the WTRU may communicate (e.g., send) one angle back to the gNB for each analog precoder (e.g., regardless of the number of transmit antennas used). Such constraints may result in a significant reduction in feedback overhead, e.g., N tThe factor of reduction, which may be significant in massive MIMO systems. The reduction may be relative to using a unit modulus constraint on the entries of the analog beamformer. In some examples, the feedback overhead of using a unit modulus constraint on the entries of the analog beamformer may scale (e.g., increase) with the number of transmit antennas. A tensor-based approach may be given as an example for solving equation (3), for example, using the introduced Vandermonde feasible set.

[0111] The analog pre-decoder may be constrained to a Vandermonde structure. In one example, when the analog pre-decoder is constrained to a Vandermonde structure, problem (3) may be reformulated as a tensor problem, which may be solved, for example, using a tensor decomposition method. For example, assuming that the channel matrix is ​​estimated at the WTRU And derive the digital SVD based pre-decoder In one example, the WTRU is formed into a matrix Then, in this example, when defining the matrix When , equation (3) can be expressed as equation (4), where is to generate a Vandermonde based predecoder F RF May be needed angle.

[0112]

[0113] Make

[0114] In one embodiment, the following two subarrays are constructed:

[0115] A=F RF (1:end-1,:), (e.g., all rows except the last row)

[0116] (e.g. all rows except the first)

[0117] Constructed Subarray A and may be shifted and / or may otherwise be the same subarray. For example, by using the matrix F RF The Vandermonde structure of the columns is constructed Subarray A and may be shifted, but may otherwise be the same subarray. Can be maintained, for example, where

[0118] In one example, let A = AΦ0, where For example, if Then equation (5) can be expressed as follows.

[0119] X0=AD0(C)B T

[0120] X1=AD1(C)B T (5)

[0121] For example, in equation (5), D p (C) may be a diagonal matrix that holds the pth row of C on its diagonal, and / or C may be a matrix that holds Φ on its pth row. p The model in equation (5) may be a dual-plate canonical multi-factor decomposition (CPD) (e.g., which may be referred to as a parallel factor (PARAFAC) analysis), such as having a Vandermonde structure in one mode. The WTRU may use type V, for example, for deriving a hybrid pre-decoder. For example, to derive a hybrid pre-decoder using type V, the WTRU may form two matrices X0 and X1 and / or concatenate them to construct a tensor The WTRU may then pass the constructed tensor to PARAFAC to obtain, for example and / or baseband pre-decoder

[0122] In one example, to illustrate the practical feasibility of the proposed tensor method, the performance may be evaluated on a 3GPP link-level channel model. The simulation parameters employed may include one or more of the following. For example, the CDL-C channel model may be used with one or more of the following: a delay spread set to 300 ns, a carrier frequency set to 28 GHz, 16-QAM modulation, a subcarrier spacing set to 60 kHz, the number of transmit and receive antennas set to 32 and 8, respectively, and a WTRU speed set to 0.5 km / hr. In one example, the BS and / or WTRU may be equipped with a uniform linear array in which the antenna elements may be separated by half a wavelength. The results may be averaged over several implementations (e.g., 200 implementations). The number of subbands may be set to 30, (e.g., K=30), where, for example, each subband may include one resource block (RB) (e.g., 12 subcarriers). The channel matrix for each subband may be obtained by averaging the channel across multiple subcarriers (e.g., 12 subcarriers). The TALS algorithm may be implemented, for example, in the Tensorlab MATLAB toolbox.

[0123] Figure 6 is a graph 600 illustrating an example of the bit error rate (BER) performance of the tensor method. Figure 7is a graph 700 illustrating an example of the running time of the tensor method. Figure 6 and Figure 7 The results shown in the figure can be used for and N s =2. Figure 6 In the example shown, an implementation for HBF Type V (e.g., T-VPAR 606) can achieve higher performance than an orthogonal matching pursuit (OMP) method 610 (e.g., Type C) and / or can achieve comparable performance to, for example, manifold optimization (MO) 604 and / or phase extraction (PE) 608 methods (e.g., Type U). The optimal method 602 can achieve higher performance than the other methods. In one example, as in Figure 7 In the embodiment of HBF type V (e.g., T-VPAR 706) can outperform PE method 704 (e.g., type U). In addition, in terms of complexity, the proposed method T-VPAR 706 (e.g., type V) can appear between OMP 708 (e.g., type C) and MO 702 (e.g., type U), as shown in FIG. Figure 7 In one example, from the perspective of feedback overhead, OMP (e.g., type C) and / or the proposed method (e.g., type V) can achieve lower overhead than PE and / or MO (e.g., type U), as shown in FIG. Figure 8 This is because for OMP and / or the proposed method, a single parameter may be reported for each Tx RF chain (e.g., for a total of For PE and / or MO methods, N may be reported for each Tx RF chain. t parameters (for example, for a total of In other words, OMP and / or the proposed method may result in N compared to PE and / or MO methods (e.g., Type U). t For a massive MIMO system, the number of transmit antennas N t The number of HBF types may be on the order of hundreds (e.g., 200), which may result in Type V and / or Type C having multiple orders of magnitude of overhead reduction relative to Type U. The preferred HBF type may be determined, for example, via one or more methods. Different HBF types may have different characteristics, which may include performance, overhead, and / or complexity. For example, HBF Type U may produce higher performance when compared to one or more other types. HBF Type U may result in higher feedback overhead and / or higher complexity when compared to one or more other types. In one example, Type C may achieve a (e.g., relatively) low level of overhead (e.g., compared to N per Tx RF antenna chains for the HBF Type U method). tIn addition or alternatively, Type C may achieve (e.g., relatively) low performance. Type V may achieve target performance. Type V may achieve (e.g., relatively) low overhead.

[0124] The WTRU may be configured to recommend and / or select a preferred HBF type (e.g., using a higher layer parameter UErecommend-HBFType). In one example, if activated, the WTRU may determine and / or report a preferred HBF type (e.g., C, U and / or V) for calculating a hybrid precoder. Fig. 9 An example of high-level steps for determining and / or reporting a preferred HBF type is provided. In some examples, the preferred HBF type may be determined based on PDSCH performance. The WTRU may select the HBF type based on the PDSCH performance. For example, different types may produce different hybrid pre-decoders, for example given the same channel input. Different types may result in different average block error rate (BLER) performance. The WTRU may switch between different types, for example based on the observed average BLER. For example, for a given target BLER (e.g., γ th ), the WTRU may derive a precoder for a HBF type with lower or minimum overhead (e.g., Type C) and / or compare the observed BLER to the target BLER. The WTRU may determine a preferred HBF type that may improve the BLER (e.g., with higher resolution). For example, if the observed BLER is greater than γ th , the WTRU may determine a preferred HBF type that may improve the BLER (e.g., with a higher resolution). The WTRU may switch to another HBF type with lower granularity (e.g., Type C or Type V). For example, if the selected HBF type (e.g., Type U) results in a higher BLER than γ th 0.01)。 WTRU may switch to another HBF type (e.g., Type C or Type V) with lower granularity at a BLER lower than (e.g., to a defined threshold). The WTRU may switch between different types, for example, using a mapping between different types and target BLERs. The WTRU may be configured with different BLER ranges. For example, the WTRU may be configured with a recommended type for each BLER range. In one example, when BLER>0.1, type C may be recommended; when BLER is between 0.01 and 0.1, type V may be recommended; and / or when BLER<0.01, type U may be recommended. The WTRU may indicate one or more criteria for determining a preferred HBF type, for example, by adding a field in the physical layer parameters under the WTRU radio access capability parameters. In one example, HBFTypeSelectPDSCH=1(0) may indicate that HBF type selection based on PDSCH performance is activated.

[0125] One or more preferred HBF types may be determined based on uplink control information (UCI) allocation and / or physical uplink control channel (PUCCH) resource configuration. The WTRU may select and / or recommend a HBF type, for example, based on the number of available UCI bits for HBF reporting. The number of available UCI bits may be limited by one or more of gNB allocation, other co-scheduled CSI reports, acknowledgement / negative acknowledgement (ACK / NACK) reports, etc. For example, the WTRU may determine the HBF type based on the available resources in the UCI allocation. Different types may be associated with a minimum required resolution level. For example, type V may have different resolution levels and / or may result in different allocations. The WTRU may determine that the available UCI is insufficient to find the HBF type and / or use a configured HBF type (e.g., type V) with the requested resolution. The WTRU may select and / or recommend a HBF type based on the payload size allocated for the HBF report. Different types may have different resolutions. For example, a type having a feedback overhead with a number of bits less than or equal to the payload size may be considered. In some examples, a type having a feedback overhead with a number of bits less than or equal to the payload size may be considered. The WTRU may determine which types result in feedback overhead that is less than or equal to the number of PUCCH payload bits (B). The WTRU may select one or more types that satisfy the payload size constraint. For example, the WTRU may select a type that results in an overhead of B. i One or more HBF types ≤ B.

[0126] Fig. 9 An example HBF process 900 for determining a preferred HBF type is illustrated. One or more portions of process 900 may be performed at a WTRU. At 902, the WTRU may estimate a channel matrix H[k]. The channel matrix H[k] may be estimated using one or more estimation algorithms, such as a maximum likelihood (ML) estimation algorithm or a minimum mean square error (MMSE) estimation algorithm. The channel matrix H[k] may be associated with the kth subband, where k=1,…,K. The WTRU may be configured to receive a configuration related to HBF processing. Alternatively or additionally, the WTRU may be configured to derive a configuration related to HBF processing, for example based on one or more measurements made by the WTRU. The configuration may include a first configuration. The WTRU may be configured to receive and / or derive a second configuration related to hybrid beamforming (HBF) processing.

[0127] At 904, the WTRU may derive analog and / or hybrid precoders associated with the configured HBF type (e.g., U-unit magnitude, C-codebook based, V-Vandermonde constraint, etc.). For example, the WTRU may derive analog and / or hybrid precoders for each configured HBF type that can be utilized at the WTRU and / or NB. The WTRU may use the channel matrix to derive one or more HBF precoders.

[0128] At 905, the WTRU may determine at least one constraint associated with each HBF type. The at least one constraint may be related to processing performance and / or feedback overhead. For example, the constraint may include one or more of payload size (e.g., allocated payload size), t, received signal-to-noise ratio (SNR), effective rank, one or more channel conditions, physical downlink shared channel (PDSCH) performance, and / or any (e.g., weighted) combination thereof. Alternatively or additionally, the constraint may include one or more of channel state information (CSI), block error rate (BLER) performance, (e.g., effective) resolution, reference signal received power (RSRP), delay spread, carrier frequency, modulation, subcarrier spacing, number of transmit and / or receive antennas, wavelength, angle, delta angle, absolute angle, relative angle, center angle, number of layers, pre-coding resource group (PRG) size, and / or WTRU speed. The HBF pre-decoder may be associated with at least one constraint related to processing performance or feedback overhead.

[0129] At 906, the WTRU may determine a preferred HBF type. For example, the preferred HBF type may be determined based on a set of preconfigured and / or measured parameters. The set of preconfigured and / or measured parameters may be associated with a configuration related to HBF processing. The preferred HBF type may be determined based on at least one network constraint associated with each HBF type and / or a set of measured parameters, for example, when the feedback size is limited and the measured performance meets the configured target performance, Vandermonde may be selected. One of the HBF types may include a Vandermonde structure. The WTRU may determine a preferred HBF from one or more of the same HBF types. For example, the WTRU may determine a preferred HBF from multiple Vandermonde types. The WTRU may determine a preferred HBF based on one or more parameters, constraints and / or measurements.

[0130] The WTRU may switch between HBF types. For example, based on a second configuration related to HBF processing and / or at least one constraint related to processing performance or feedback overhead associated with each of the multiple HBF types, the WTRU may switch from a first preferred HBF type among the multiple HBF types to a second preferred HBF type. Switching from the first preferred HBF type among the multiple HBF types may be based on a triggering event. The triggering event may include satisfying one or more of a performance threshold, a threshold associated with a monitoring value, and a preconfigured condition. Additionally or alternatively, switching or selecting the HBF type may be based at least in part on an angle, for example as described herein.

[0131] At 908, the WTRU may report (e.g., implicitly and / or explicitly) the selected HBF type and / or HBF-related parameters. The HBF-related parameters may include the associated hybrid precoder (e.g., F RF 、F BB ) and / or an effective rank or an effective rank indicator.

[0132] The WTRU may report HBF information related to a preferred HBF type and associated parameters among multiple HBF types to a base station based on a configuration related to HBF processing and / or at least one constraint related to processing performance or feedback overhead associated with each of the multiple HBF types. The HBF information may indicate at least one of a preferred HBF type, a HBF pre-decoder associated with the preferred HBF type, or an effective rank associated with the preferred HBF type. The WTRU may report second HBF information related to a second preferred HBF type and associated parameters among multiple HBF types to the base station. The second HBF information may indicate at least one of a second preferred HBF type, a HBF pre-decoder associated with the second preferred HBF type, or an effective rank associated with the second preferred HBF type. Reporting to the base station may include reporting a Vandermonde-based codebook derived from one or more measurements performed by the WTRU.

[0133] The WTRU may receive one or more configurations. One or more configurations may be received from a base station. After receiving an initial configuration indicating a HBF type and / or other HBF information from a base station, the WTRU may receive one or more updated configurations. For example, in response to a preferred HBF type and / or HBF information, the WTRU may receive a configuration including information related to a preferred HBF type or to another HBF type. For example, the configuration may include confirmation of a preferred HBF type. The configuration may alternatively or additionally include one or more other HBF types. The configuration may include confirmation of a pre-decoder associated with a preferred HBF type. Additionally or alternatively, the configuration may include one or more other HBF pre-decoders. The configuration may include confirmation of an effective rank associated with a preferred HBF type. In some examples, the configuration may include information associated with one or more of a preferred HBF type, another HBF type, a HBF pre-decoder associated with a preferred HBF type, and a HBF pre-decoder associated with another HBF type. Additionally or alternatively, the configuration may include a preferred HBF type and / or a HBF pre-decoder associated with a HBF type selected from an effective rank associated with the preferred HBF type.Alternatively or additionally, the configuration may include another HBF type and / or another HBF pre-decoder associated with a HBF type selected from an effective rank associated with the preferred HBF type.

[0134] The WTRU may perform HBF processing based on the configuration. The HBF processing may include a determination based on one or more constraints, parameters and / or feedback overhead. The WTRU may use the configuration for one or more subsequent communications. For example, based on the configuration and / or one or more constraints, parameters and / or feedback overhead, the WTRU may switch from one HBF type to another HBF type. For example, HBF information may be reported to the base station. The HBF information may be related to the preferred HBF type. Additionally or alternatively, the WTRU may transmit one or more constraints, parameters and / or feedback overhead to the base station. The HBF information may indicate one or more of a preferred HBF type, another HBF type, a HBF precoder associated with the preferred HBF type, a precoder associated with another HBF type, an effective rank associated with the preferred HBF type, and an effective rank associated with another HBF type.

[0135] In some examples, one or more preferred HBF types may be determined and / or reported based on one or more WTRU measurements. The WTRU may select and / or recommend a HBF type based on a combination of different measurements, for example, if the higher layer parameter UErecommend-HBFTypeSelection is activated. The WTRU may select and / or recommend a HBF type based on one or more measurements (e.g., a combination of different measurements) including: CSI-related measurements, rank measurements, number of layers (N), L), available computing resources (e.g., number of idle CPUs), received SNR, number of sub-bands, etc. In one example, the WTRU may calculate the effective channel associated with type U, C, V rank (e.g., ). For example, the effective channel may be defined as in equation (6).

[0136]

[0137] Where W RF *(i) and is an analog pre-decoder and combiner derived from type i, and is the estimated channel matrix at subband k, for k=1, ..., K, and i may be U, V, C. The effective channel may, for example, incorporate the effects of analog beamforming on one or more (e.g., both) of the transmit side and the receive side. The WTRU may calculate the effective rank (e.g., which may be the rank of the effective channel) as in equation (7).

[0138]

[0139] The WTRU may determine the L ,N RF , ) to select and / or recommend a HBF type. For example, the WTRU may select between HBF types that produce an effective rank greater than the number of configured layers. The WTRU may report one or more effective ranks associated with one or more (e.g., different) HBF types. The WTRU may select and / or recommend a HBF type based on the received SNR. In one example, different types may behave differently at one or more (e.g., various) SNR levels. The WTRU may recommend and / or select one or more HBF types, for example, based on one or more measured SNRs. For example, compared to type U, type V may produce greater performance at low SNR areas, and / or type U may produce greater performance at high SNRs. The WTRU may select and / or recommend a HBF type based on the number of sub-bands. In one example, the number of digital pre-decoders may depend on the number of configured sub-bands. In one example, the complexity of finding a digital (e.g., baseband) pre-decoder may scale with the number of sub-bands. In one example, different types may require different calculations as the number of sub-bands increases. The WTRU may recommend and / or select a HBF type based on one or more of the allocated bandwidth portion, the sub-band size, and / or the WTRU HBF computing capability (e.g., the amount of available CPU resources). In one example, the WTRU may select and / or recommend one or more HBF types based on one or more (e.g., different) measurement quantities, for example with different weights for each quantity. The WTRU may reconstruct a feature vector comprising different parameters. For example, the feature vector may be formed as x=[SNR, BLER, eff.rank, numberofbits, channelquality, K, subcarrierapacing]. The WTRU may select and / or recommend a HBF type, for example based on a function f(x). The function f(x) may take the feature vector as input and / or may produce one of the configured types.

[0140] The WTRU may be configured with one or more triggers, for example, for the WTRU to report a preferred HBF type or provide a HBF type recommendation. For example, one or more triggers may cause process 900 or one or more parts thereof to be initiated. One or more triggers may enable, for example, the selection and / or reporting of a preferred HBF type and / or related parameters (e.g., effective rank) from a set of configured HBF types. In some examples, the WTRU may be triggered to report a preferred HBF type based on one of the following: a time-based trigger and an event-based trigger. For example, a time-based trigger may include aperiodic, periodic, and / or semi-persistent reporting of HBF type recommendations and / or related parameters (e.g., effective rank). In another time-based trigger example, the WTRU may recommend a preferred HBF type based on a preconfigured reporting periodicity. In other time-based trigger examples, the WTRU may perform aperiodic reporting of a preferred HBF type when decoding a specific DCI format that triggers a non-periodic HBF type recommendation trigger state. In another time-based trigger example, the WTRU may recommend a preferred HBF type in a semi-persistent mode on a data channel (e.g., PUSCH). An event-based trigger may include the WTRU reporting a preferred HBF type based on a monitored metric (e.g., exceeding a preconfigured threshold or condition). In one example, an event-based trigger may be when the (e.g., measured) number of consecutive NACKs exceeds a certain preconfigured number. In another example of an event-based trigger, the WTRU may report a preferred HBF type based on a relationship between a measured rank (e.g., a channel rank) and a measured effective rank (e.g., a rank of an effective channel, such as including an analog pre-decoder and a combiner). For example, when the measured rank is greater than the measured effective rank, the WTRU may report a preferred HBF type.

[0141] The WTRU may be configured with one or more triggers, such as for HBF type switching. For example, the WTRU may be configured with a performance threshold for HBF type switching. The WTRU may receive the configuration via radio resource control (RRC) signaling. In another example, the WTRU may be triggered to switch HBF type based on a preconfigured / predefined performance threshold. For example, the threshold may represent a digital precoder F opt and hybrid pre-decoder F RF F BB The normalized mean square error (NMSE) between the two HBF types (e.g., U, C, V) may be associated with different HBF types. The WTRU may switch to the HBF type with the minimum error that meets the configured threshold. In another example, the WTRU may switch to the HBF type that meets the configured threshold and / or has the minimum feedback overhead.

[0142] The precoder may be determined, for example, under codebook constraints. There is an overall optimization of the codebook constraints for the analog precoder (e.g., such that FRF The columns of are taken from the codebook C) can be reformulated as in equation (8)

[0143]

[0144] Make Among them, F RF The codebook C can be used instead, and / or the matrix Matrix F BB [k] Available N t ×N s matrix For example, A sparse constraint is imposed to ensure that only rows may be non-zero and the remaining rows may be zero. In one example, the sparse constraint may ensure that only For example, the set S may contain the range {1,...,N t} within different items and / or may indicate The index of the all-zero row of . The DFT codebook may be used in the 3GPP standard, for example if the codebook is orthogonal. For example, the optimization may be as in equation (9).

[0145]

[0146] Make

[0147] This problem (e.g., Equation (9)) can be solved (e.g., efficiently) and / or can have a global optimal solution. RF and F BB [k] can be expressed as given in equation (10).

[0148]

[0149] For example, to incorporate the power constraint Also available in the form Additional normalization of .

[0150] One or more preferred HBF types and / or HBF pre-decoders may be reported. For example, the WTRU may (e.g., be capable of) supporting more than one type of HBF weight reporting (e.g., HBF Type U, HBF Type C, HBF Type V, etc.). The WTRU may indicate the supported HBF weight reporting types, for example in the WTRU capability information. A WTRU supporting HBF may report analog and / or digital pre-decoder values ​​(F RF 、F BB). A WTRU supporting HBF may report analog and digital precoder values ​​to the gNB (F RF 、F BB ) both. The analog precoder value may be applied to the entire channel. The digital precoder may be applied to one or more of individual subcarriers, subbands, resource elements, and resource blocks. In some examples, the granularity of the analog precoder report may be configurable by the gNB. The report configuration may be configured in a semi-static manner using RRC signaling. In one example, the WTRU CSI report may include analog and / or digital precoder weights (e.g., both) in a single report. In one example, the WTRU CSI report may include both analog and digital precoder weights in one or more reports. In one example, the report may include an effective rank indicator. The effective rank indicator may be used to determine, for example, the maximum number of layers that can be transmitted in the next time slot (e.g., associated with it). The size of the report may vary, for example, depending on the selected report type. Alternatively or additionally, the WTRU may divide the information into multiple (e.g., two) parts. The first part may include the effective channel rank indicator. The second part may include weights determined using the configured type. In one example, the WTRU may divide the reporting of analog and digital weights into two or more reports. In one example, the WTRU may be configured (e.g., by the gNB) to use one of the available forms of CSI reporting. In one example, the configuration may occur as one or more of control channel signaling, part of RRC signaling, and / or via a MAC-CE indication. The WTRU may be configured to use a specific CSI report type, for example, at a specific time. The WTRU may be configured with a time when the WTRU may need to switch from a specific CSI reporting configuration (e.g., report segmentation, estimation technique, etc.) to a new configuration. Alternatively or additionally, the WTRU may not receive an explicit time delay for starting and / or switching to a specific reporting configuration. The WTRU may use a default configuration, which may, for example, have been previously configured.

[0151] The indication of the HBF type and / or pre-decoder may be implicit. The WTRU may be configured to utilize one or more (e.g., either) of a constant modulus method and a Vandermonde-based method, for example, to determine the HBF weight. The gNB may configure the WTRU. The size of the report corresponding to the two types may be different, for example, due to different amounts of feedback generated for the two types. The WTRU may be implicitly signaled by the gNB to use a constant modulus and / or Vandermonde-based codebook, for example, depending on the size of the resource grant intended for report transmission. The WTRU may be implicitly signaled (e.g., by the gNB) to use a constant modulus and / or Vandermonde-based codebook (e.g., either), for example, depending on the size of the resource grant intended for report transmission. A larger grant size may indicate a constant modulus method. A smaller grant may indicate that the gNB is requesting a derived Vandermonde-based codebook. Alternatively or additionally, a smaller grant may indicate that the gNB is requesting a codebook-based CSI report. In one example, the selection between the constant modulus method and the Vandermonde-based method may be (e.g., also) implicitly signaled, e.g., using the duration between request and / or scheduled report start times and / or periodicity (e.g., in the case of periodic reporting). In another example, the constant modulus method may be more computationally intensive than the Vandermonde-based method. The constant modulus method may require larger gaps between requests and / or responses and / or periodicity between subsequent reports (e.g., in the case of periodic reporting).

[0152] The indication of the HBF type and / or pre-decoder may be explicit. The WTRU may be explicitly signaled / configured (e.g., by the gNB) to use the constant modulus method and / or the Vandermonde-based method, for example, for CSI reporting. The indication of the HBF type and / or pre-decoder may be included in the PDCCH, for example, via RRC signaling and / or via MAC-CE signaling. In one example, the HBF type and / or pre-decoder (e.g., an indication thereof) may be included in the PDCCH (e.g., via RRC signaling or via MAC-CE signaling). In another example, the time when the new configuration takes effect may be explicitly signaled and / or the WTRU may use pre-configured default values. The time when the new configuration takes effect may be explicitly signaled or the WTRU may use pre-configured default values. The codebook-based and / or Vandermonde-based methods may use the same or different amounts of resources for reporting. For example, if both the codebook-based and Vandermonde-based methods use the same amount of resources for reporting, the WTRU may include a special indicator for each selected type. The Vandermonde-based codebook may have a dynamic design. For example, the proposed HBF Type V may exhibit a favorable performance-overhead tradeoff, since each FRF vector may need to report only one phase to be generated. In another example, the feedback overhead may be determined by how the resulting Vandermonde-based phase is quantized.

[0153] (Eg, each) Vandermonde angle value may be quantized. Each angle may be transmitted back in a bit stream of T+Q bits, e.g., having the following format:

[0154] t T-1 …t0q Q-1 …q0

[0155] Where the T bit is used to represent the quantization type table / equation and the Q bit is used to represent the quantization value or index to the lookup table. For example, based on WTRU measurements, the quantization type may be reported for a longer duration. The WTRU may indicate one or more different quantization types, for example, based on channel variations. In one example, a non-negative integer value is defined as the quantization type t T-1 In another example, a non-negative integer value is defined as a quantized value q=q Q-1 ...q0. Various values ​​may be predefined. In some examples, (e.g., only) a value T (e.g., required) may be predefined. In another example, different quantization types may use different Q values, e.g., based on the required resolution. For example, if T=2, there may be up to 4 quantization types. In another example, type t0 may be reserved for absolute quantization. The remaining T-1 (t T-1 …t1) types may be used for relative quantization, which may be centered, for example, on a previous value of an angle known to one or more (eg, two) sides of the communication. The WTRU may use a variable T. In one example, the variable T may depend on the value of t.

[0156] Absolute angle quantization, incremental angle quantization, and / or center angle quantization may be determined. Absolute (e.g., center) angle quantization may be used, for example, when an angle value is first transmitted and / or (e.g., just after) communication has recovered from a failure. In one example, in this case, the angle resolution may be determined as in equation (11).

[0157]

[0158] For example, if Q is 4, the absolute angle can be specified with a resolution of π / 8. In one example, at the receiving side, the actual angle can be calculated using the received q value as in equation (12).

[0159]

[0160] Relative angle quantization may be determined. For example, relative angle quantization may play an important role in determining feedback overhead and / or performance. The change in the Vandermonde angle over time may be related to the degree of time variation of the channel. For example, the change in the Vandermonde angle over time may be implicitly associated with how the channel varies over time. The WTRU may be configured to determine an angular range around a determined center angle (e.g., to construct a phase subset with a selected resolution). The WTRU may choose to (e.g., iteratively) transmit updates and / or offsets of the measured angle reported in a previous time slot. The (e.g., remaining) T-1 relative angle quantization types may be based on a table and / or formula. The angle adjustment δ may be calculated, for example, from a table and / or using a formula. The actual angle may be (e.g., iteratively) updated to α i =α i-1 +δ, where α i-1 The angle adjustment value δ may be obtained using a known predefined lookup table, for example, in table-based relative quantization.

[0161] Fig.10 An example of a table 1000 that can be used for one of the predefined quantization types is illustrated, e.g., with Q=3. The values ​​in the table may be arranged linearly and / or nonlinearly. For example, there may be a higher resolution near zero and / or a lower resolution as it moves away from zero. A predefined formula may be used to calculate δ from q, e.g., in a formula-based relative quantization. Although table 1000 illustrates q values ​​of 0 to 7, q may be any value (e.g., a number). Additionally or alternatively, v may be calculated based on any value of q.

[0162] Fig.11 An example of a graph 1100 depicting a scenario is illustrated where Q=4 and the predefined formula for calculating δ from q is as in equation (13).

[0163]

[0164] Fig.12 An example of a table 1200 describing an example of the results of a formula as in equation (13) is illustrated. For example, when Q = 5, there may be an absolute quantization. When Q = 4, there may be a relative formula.

[0165] A transmitter process may be performed. For example, the transmitter process may be performed for the first time, periodically, and / or upon recovery from a failure. The WTRU may use quantization type t0, for example, to report absolute / center angles. The WTRU may select between different quantization types, for example, for relative angle reporting based on a predefined threshold. The WTRU may use the following process to determine the quantization type. In one example, at the beginning of a communication and / or periodically, the WTRU may use quantization type t0 (t=0). In another example, the WTRU may perform the following operations:

[0166] if Then use t=0

[0167] Otherwise if Then use t = 2

[0168] Otherwise use t=3

[0169] The WTRU may determine α c Additionally or alternatively, the WTRU may determine the absolute and / or central angle α based on the determined absolute and / or central angle α. c , to determine α c For example, the WTRU may determine a set of angles around q Alpha c +δα and α c A set of uniformly quantized angles between –δα. δα and / or α can be selected from preconfigured values q For example, δα may be selected from (e.g., four) different preconfigured values ​​(e.g., 5°, 10°, 15°, 20°, etc.). For example, δα may be selected from (e.g., four) different preconfigured values ​​that may require (e.g., two) bits to indicate. In one example, the quantization step size α q It can be selected from predetermined values ​​(eg, 0.5°, 1°, etc.).

[0170] Setting the bounds and / or quantization step size may be determined by the WTRU, for example, based on channel measurements. The WTRU may determine δα and / or α based on the estimated Doppler and / or measured coherence time of the channel. q In one example, a higher coherence time may produce smaller variations in the channel, which may, for example, (in turn, for example) result in smaller δα. The WTRU may determine δα, for example, based on tracking changes in the estimated angle of arrival and / or by performing positioning-related measurements based on a positioning reference signal (PRS). The WTRU may determine δα and / or α q (e.g., based on the allocated payload size), such as for reporting type V weights. Fig.13 An example of a WTRU process 1300 for adaptive Vandermonde based codebook design is illustrated. In one example, Fig.13 WTRU processes for adaptively designing and / or reporting a Vandermonde-based codebook are highlighted. At 1302, the WTRU may estimate a channel matrix H[k]. The channel matrix H[k] may be associated with the kth subband, where k=1,…,K. In one example, at 1304, the WTRU may derive an analog and / or hybrid precoder associated with the configured HBF type (e.g., U-unit magnitude, C-based codebook, V-Vandermonde constraint, etc.). At 1306, the WTRU may perform a process for (e.g., adaptive) Vandermonde-based codebook design (e.g., based on channel measurements and / or positioning measurements). For example, at 1308, the WTRU may signal back the (e.g., designed) codebook (e.g., reporting relative and / or absolute angles).

[0171] The WTRU may be configured with one or more triggers, e.g., for HBF type V parameter / codebook update (e.g., Vandermonde based codebook). The WTRU may be triggered to select / update the Vandermonde based codebook, e.g., based on a preconfigured threshold (e.g., number of consecutive NACKs or target BLER) and / or based on the UCI allocation for HBF reporting. A change in the UCI allocation associated with the HBF reporting may trigger the WTRU to adapt the Vandermonde based codebook parameters (e.g., relative angle), e.g., to accommodate the new UCI allocation. The WTRU may be triggered to adapt the Vandermonde based codebook parameters, e.g., when the PDSCH performance is good and / or a low resolution codebook may maintain the same performance with reduced overhead. The WTRU may, e.g., report the modified codebook parameters (e.g., relative and / or absolute angle) to the gNB. The WTRU may, e.g., send (e.g., transmit) a trigger codebook update message, e.g., before transmitting the update information. The WTRU may use a codebook update message (e.g., HBF-Vcodebookupdate) to notify the gNB of the proposed update. The codebook update message may be included with (eg, as part of) one or more of the UCI, PUCCH, PUSCH, and MAC CE. The proposed update may include all or part of the codebook parameters.

[0172] Although features and elements are described above in particular combinations, it will be understood by one of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of non-transitory computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a WTRU, terminal, base station, RNC, or any host computer.

[0173] In addition, in the above embodiments, processing platforms, computing systems, controllers, and other devices containing processors are indicated. These devices may include at least one central processing unit ("CPU") and memory. According to the practice of those skilled in the art of computer programming, references to symbolic representations of actions and operations or instructions may be performed by various CPUs and memories.

[0174] Those of ordinary skill in the art will appreciate that the actions and symbolic representations of operations or instructions include the manipulation of electrical signals by the CPU. The electrical system represents data bits, which may result in the ultimate transformation of electrical signals or the reduction of electrical signals and the retention of data bits at memory locations in the memory system, thereby reconfiguring or otherwise changing the operation of the CPU and performing other processing of signals. The memory location that holds the data bits is a physical location that has specific electrical, magnetic, optical, or organic properties that correspond to or represent the data bits. It should be understood that the exemplary embodiments are not limited to the above-mentioned platforms or CPUs, and other platforms and CPUs may also support the provided methods.

[0175] The data bits may also be maintained on computer-readable media, including magnetic disks, optical disks, and any other volatile (e.g., random access memory ("RAM")) or non-volatile (e.g., read-only memory ("ROM")) mass storage system readable by the CPU. The computer-readable media may include cooperating or interconnected computer-readable media that reside solely on the processing system or distributed across multiple interconnected processing systems that may be local or remote relative to the processing system. It should be understood that the representative embodiments are not limited to the above-described memories, and other platforms and memories may also support the described methods.

[0176] In an exemplary embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile unit, a network element, and / or any other computing device.

[0177] The foregoing detailed description has presented various embodiments of devices and / or processes through the use of block diagrams, flow charts, and / or examples.

[0178] Where such block diagrams, flow charts and / or examples include one or more functions and / or operations, it should be understood by those skilled in the art that each function and / or operation within such block diagrams, flow charts or examples may be implemented individually and / or collectively by a wide range of hardware, software, firmware or (e.g., substantially) any combination thereof. Suitable processors include (shown by way of example) general purpose processors, special purpose processors, conventional processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, application specific integrated circuits (ASICs), application specific standard products (ASSPs), field programmable gate arrays (FPGAs) circuits, any other type of integrated circuit (IC) and / or state machines.

[0179] Although features and elements are provided above in specific combinations, each feature or element may be used alone or in any combination with other features and elements. The present disclosure is not limited to the specific embodiments described in this patent application, which are intended to be illustrative of various aspects. Many modifications and variations can be made without departing from the essence and scope of the present invention, as they will be apparent to those skilled in the art. Unless explicitly provided as such, any element, action or description used in the present application specification should not be understood as being essential or necessary to the present invention. According to the foregoing description, in addition to those listed herein, functionally equivalent methods and devices within the scope of the present disclosure will be apparent to those skilled in the art. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is limited only to the terms of the appended claims and the full range of equivalent forms of such entitled claims. It should be understood that the present disclosure is not limited to a specific method or system.

[0180] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0181] In certain representative embodiments, several portions of the subject matter described herein may be implemented via application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), digital signal processors (DSPs), and / or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein may be equivalently implemented in whole or in part in an integrated circuit as one or more computer programs running on one or more computers (e.g., one or more programs running on one or more computer systems), one or more programs running on one or more processors (e.g., one or more programs running on one or more microprocessors), firmware, or nearly any combination thereof, and that designing circuit systems and / or writing software and / or firmware code will be well within the technical scope of those skilled in the art in accordance with the present disclosure. In addition or alternatively, those skilled in the art will appreciate that the mechanisms of the subject matter described herein may be distributed as program products in a variety of forms, and that the exemplary embodiments of the subject matter described herein apply regardless of the specific type of signal-bearing medium used to actually perform the distribution. Examples of signal-bearing media include, but are not limited to, the following: recordable type media (such as floppy disks, hard drives, CDs, DVDs, digital tapes, computer memory, etc.); and transmission type media (such as digital and / or analog communication media (e.g., fiber optic cables, waveguides, wired communication links, wireless communication links, etc.)).

[0182] The subject matter described herein sometimes illustrates different components contained within or connected to different other components. It should be understood that such depicted architectures are merely examples, and that in fact many other architectures that achieve the same functionality can be implemented. In a conceptual sense, any arrangement of components that achieve the same functionality is effectively "associated" such that the desired functionality can be achieved.

[0183] While the invention is shown and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made to the details within the scope and range of equivalents of the claims without departing from the invention.

[0184] Throughout this disclosure, it will be appreciated by those skilled in the art that certain representative embodiments may be used in alternative forms or in combination with other representative embodiments.

[0185] Although features and elements are described above in specific combinations, it will be understood by those of ordinary skill in the art that each feature or element may be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of non-transitory computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as built-in hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and digital versatile disks (DVDs)). A processor associated with software may be used to implement a radio frequency transceiver for a UE, WTRU, terminal, base station, RNC, or any host computer.

[0186] Suitable processors include, by way of example, 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, an application specific integrated circuit (ASIC), an application specific standard product (ASSP), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), and / or state machine.

[0187] A processor in association with software may be used to implement the use of a radio frequency transceiver in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, mobility management entity (MME) or evolved packet core (EPC) or any host. The WTRU may be used in conjunction with a module, which may be implemented in hardware and / or software including: a software defined radio (SDR) and other components such as a camera, video camera module, videophone, speakerphone, vibration device, speaker, microphone, television transceiver, hands-free headset, keyboard, module, a frequency modulation (FM) radio unit, a near field communication (NFC) module, a liquid crystal display (LCD) display unit, an organic light emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an internet browser, and / or any wireless local area network (WLAN) or ultra-wideband (UWB) module.

[0188] Although the present invention has been described in terms of a communication system, it is contemplated that the system may be implemented in software on a microprocessor / general purpose computer (not shown). In certain embodiments, one or more of the functions of the various components may be implemented in software controlling a general purpose computer.

[0189] Furthermore, while the invention has been shown and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made to the details within the scope and range of equivalents of the claims without departing from the invention.

Claims

1. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: determining at least one constraint related to processing performance or feedback overhead associated with each of a plurality of hybrid beamforming (HBF) types; Based on the first configuration related to HBF processing and the at least one constraint related to processing performance or feedback overhead associated with each of the multiple HBF types, reporting HBF information related to a preferred HBF type and associated parameters among the multiple HBF types to a base station, wherein the HBF information indicates at least one of the preferred HBF type, a HBF precoder associated with the preferred HBF type, or an effective rank associated with the preferred HBF type; receiving a second configuration in response to the HBF information, wherein the second configuration includes information related to the preferred HBF type or another HBF type; and The HBF process is performed based on the second configuration.

2. The method according to claim 1, further comprising: determining a channel matrix associated with the frequency subband; deriving one or more HBF pre-decoders using the channel matrix, wherein the HBF pre-decoders are associated with the at least one constraint related to processing performance or feedback overhead; as well as The preferred HBF type is determined based on a set of pre-configured parameters associated with the configuration related to HBF processing. The method of claim 1 , wherein one of the HBF types comprises a Vandermonde structure.

4. The method of claim 1, wherein the preferred HBF type comprises a first preferred HBF type, the method further comprising: switching from the first preferred HBF type to a second preferred HBF type among the plurality of HBF types based on the second configuration and the at least one constraint related to processing performance or feedback overhead associated with each of the plurality of HBF types; as well as Second HBF information related to the second preferred HBF type among the multiple HBF types and associated parameters is reported to the base station, wherein the second HBF information indicates at least one of the second preferred HBF type, a HBF precoder associated with the second preferred HBF type, or an effective rank associated with the second preferred HBF type.

5. The method of claim 3, wherein reporting to the base station further comprises reporting a Vandermonde-based codebook derived from one or more measurements made by the WTRU. The method of claim 4 , wherein switching from the first preferred HBF type to a second preferred HBF type among the plurality of HBF types is based on a triggering event. 7 . The method of claim 6 , wherein the triggering event comprises satisfying one or more of a performance threshold, a threshold associated with a monitoring value, and a preconfigured condition.

8. The method of claim 5, wherein the derived Vandermonde-based codebook is derived from a plurality of Vandermonde-based codebooks.

9. The method of claim 1, further comprising deriving the first configuration related to HBF processing based on one or more measurements made by the WTRU.

10. The method of claim 1, further comprising deriving one or more HBF pre-decoders using the channel matrix, wherein the HBF pre-decoders are associated with the at least one constraint related to processing performance or feedback overhead; and wherein the constraint comprises a measurement angle.

11. A wireless transmit / receive unit (WTRU), the wireless transmit / receive unit (WTRU) comprising a processor, the processor configured to: determining at least one constraint related to processing performance or feedback overhead associated with each of a plurality of hybrid beamforming (HBF) types; Based on the first configuration related to HBF processing and the at least one constraint related to processing performance or feedback overhead associated with each of the multiple HBF types, reporting HBF information related to a preferred HBF type and associated parameters among the multiple HBF types to a base station, wherein the HBF information indicates at least one of the preferred HBF type, a HBF precoder associated with the preferred HBF type, or an effective rank associated with the preferred HBF type; receiving a second configuration in response to the HBF information, wherein the second configuration includes information related to the preferred HBF type or another HBF type; and The HBF process is performed based on the second configuration.

12. The WTRU of claim 11 , wherein the processor is further configured to: determining a channel matrix associated with the frequency subband; deriving one or more HBF pre-decoders using the channel matrix, wherein the HBF pre-decoders are associated with the at least one constraint related to processing performance or feedback overhead; and The preferred HBF type is determined based on a set of pre-configured parameters associated with the configuration related to HBF processing.

13. The WTRU of claim 11, wherein one of the HBF types comprises a Vandermonde structure.

14. The WTRU of claim 11 , wherein the preferred HBF type comprises a first preferred HBF type, the processor and memory being further configured to: switching from the first preferred HBF type to a second preferred HBF type among the plurality of HBF types based on the second configuration and the at least one constraint related to processing performance or feedback overhead associated with each of the plurality of HBF types; and Second HBF information related to the second preferred HBF type among the multiple HBF types and associated parameters is reported to the base station, wherein the second HBF information indicates at least one of the second preferred HBF type, a HBF precoder associated with the second preferred HBF type, or an effective rank associated with the second preferred HBF type.

15. The WTRU of claim 13, wherein reporting to the base station further comprises reporting a Vandermonde-based codebook derived from one or more measurements made by the WTRU.

16. The WTRU of claim 14, wherein switching from the first preferred HBF type to a second preferred HBF type among the plurality of HBF types is based on a triggering event.

17. The WTRU of claim 16, wherein the triggering event comprises satisfying one or more of a performance threshold, a threshold associated with a monitored value, and a preconfigured condition.

18. The WTRU of claim 15, wherein the derived Vandermonde-based codebook is derived from a plurality of Vandermonde-based codebooks.

19. The WTRU of claim 11 wherein the processor is further configured to derive the first configuration related to HBF processing based on one or more measurements made by the WTRU.

20. The WTRU of claim 11, wherein the processor is further configured to derive one or more HBF pre-decoders using the channel matrix, wherein the HBF pre-decoders are associated with the at least one constraint related to processing performance or feedback overhead; And wherein the constraint comprises measuring an angle.

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