EP4649597A1

EP4649597A1 - Method for framework for channel based beamforming

Info

Publication number: EP4649597A1
Application number: EP23713270.9A
Authority: EP
Inventors: Yushu Zhang
Original assignee: Google LLC
Current assignee: Google LLC
Priority date: 2023-02-17
Filing date: 2023-02-17
Publication date: 2025-11-19
Also published as: CN120642228A; WO2024168863A1

Abstract

Wireless communication apparatuses, methods, including computer programs encoded on storage media, are provided for beamforming weight measurement and report. A UE quantizes (310, 410) beamforming weights based on measured quality of one or more downlink reference signals, RSs, emitted by a network entity, NE, using a plurality of antenna ports. The UE sends (312, 412), to the NE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports. The UE may select the at least one set of the beamforming weights based on a predetermined rule.

Description

METHOD FOR FRAMEWORK FOR CHANNEL BASED BEAMFORMING

TECHNICAL FIELD

The present disclosure relates generally to wireless communication, and more particularly, to beamforming in wireless communications.

BACKGROUND

The Third Generation Partnership Project (3GPP) specifies a radio interface referred to as fifth generation (5G) new radio (NR) (5G NR) . An architecture for a 5G NR wireless communication system includes a 5G core (5GC) network, a 5G radio access network (5G-RAN) , a user equipment (UE) , etc. The 5G NR architecture seeks to provide increased data rates, decreased latency, and/or increased capacity compared to prior generation cellular communication systems.
Wireless communication systems, in general, may be configured to provide various telecommunication services (e.g., telephony, video, data, messaging, broadcasts, etc. ) based on multiple-access technologies, such as orthogonal frequency division multiple access (OFDMA) technologies, that support communication with multiple UEs. Improvements in mobile broadband continue the progression of such wireless communication technologies. For example, in the conventional beamforming, the beam directions of the selected (as being best) beam (s) may not actually match the best directions for a UE.
BRIEF SUMMARY
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects. This summary neither identifies key or critical elements of all aspects nor delineates the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
Conventionally, the network entity and the UE perform the beam management using codebook-based beamforming. In codebook-based beamforming, specific beam (s) and thus (predetermined) beam directions are identified as being the best. However, in the codebook-based beamforming, the beam directions of the selected (as being best) beam (s) may not actually match the best directions for a UE.
Aspects of the present disclosure address the above-noted and other deficiencies by using channel-based beamforming. In the channel-based beamforming, the UE or the network entity obtains the raw channel or the eigenvector of the raw channel, then the UE or the NE identifies the best UE beam and NE beam based on the eigenvectors and eigenvalues of the raw channel. In some examples, the NE may transmit a control signaling configuring the UE to generate a beamforming weight report based on the multi-port RS or multi-resource RSs. The control signal configures the beamforming weight report to select at least one set of beamforming weights based on a predetermined rule. Then the NE transmits the multi-port RS or multi-resource RSs. The UE measures and quantizes the beamforming weights based on measured quality of the multi-port RS or multi-resource RSs. Then, the UE sends the beamforming weight report indicating the beamforming weights. The NE uses the beamforming weight report to generate a beam used for communicating with the UE.
According to some aspects, a UE quantizes beamforming weights based on measured quality of one or more downlink reference signals, RSs, emitted by a network entity, NE, using a plurality of antenna ports. The UE sends, to the NE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports.
According to some aspects, a NE configures a beamforming weight report associated with one or more reference signals, RSs. The NE receives, from a UE, the beamforming weight report including beamforming weights based on a measured quality of the one or more RSs.
Advantageously, by using channel-based beamforming, the network entity and/or the UE may identify a better network beam or UE beam compared to codebook-based beamforming. Thus, the network entity and the UE perform the beam management more effectively, resulting in higher signal receiving power or signal-to-noise ratio. Therefore, the channel-based beamforming improves the performance of the wireless communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of a wireless communications system that includes a plurality of user equipments (UEs) and network entities in communication over one or more cells.
FIG. 2 a block diagram illustrating an example of addressing problems in codebook-based beamforming.
FIG. 3 is a signaling diagram illustrating an example of communications between a UE and a network entity for multi-port RS based beamforming weight measurement and report.
FIG. 4 is a block diagram illustrating an example of UE behavior for multi-port RS based beamforming weight measurement and report.
FIG. 5 is a block diagram illustrating an example of network entity behavior for multi-port RS based beamforming weight measurement and report.
FIG. 6 is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report.
FIG. 7A and FIG. 7B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report.
FIG. 8A is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) in each symbol for phase tracking with up to 3 ports per symbol.
FIG. 8B is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) in each symbol for phase tracking with up to 2 ports per symbol.
FIG. 9A is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one additional port in each symbol for phase tracking with up to 3 ports per symbol.
FIG. 9B is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one additional port in each symbol for phase tracking with up to 2 ports per symbol.
FIG. 10A and FIG. 10B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) without OCC in each symbol for phase tracking with up to 3 ports per symbol.
FIG. 11A and FIG. 11B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) without OCC in each symbol for phase tracking with up to 2 ports per symbol.
FIG. 12A and FIG. 12B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report with one additional port without OCC in each symbol for phase tracking.
FIG. 13 is a block diagram illustrating an example of partial antenna or antenna port measurement.
FIG. 14 is a block diagram illustrating an example of the beamforming weight report with a full eigenvector report.
FIG. 15 is a block diagram illustrating an example of beamforming weight report with a NZP coefficients only report.
FIG. 16 is a block diagram illustrating an example of beamforming weight report with a top-N strongest coefficients only report.
FIG. 17 is a block diagram illustrating an example of beamforming weights grouping and codebook subset restriction for a codebook based eigenvector report.
FIG. 18 is a signaling diagram illustrating an example of communications between a UE and a network entity for multi-resource RS based beamforming weight measurement and report.
FIG. 19 is a block diagram illustrating an example of UE behavior for multi-resource RS based beamforming weight measurement and report.
FIG. 20 is a block diagram illustrating an example of network entity behavior for multi-resource RS based beamforming weight measurement and report.
FIG. 21 is a block diagram illustrating an example of the multi-resource RS with antenna or antenna port switching.
FIG. 22 is a block diagram illustrating an example of the multi-resource RS with partial antenna or antenna port switching.
FIG. 23 is a block diagram illustrating an example of multi-resource RS transmission with antenna switching first.
FIG. 24 is a block diagram illustrating an example of multi-resource RS transmission with repetition first.
FIG. 25 is a flowchart of a method of wireless communication at a UE for beamforming weight measurement and report.
FIG. 26 is a flowchart of a method of wireless communication at a network entity for beamforming weight measurement and report.
FIG. 27 is a diagram illustrating a hardware implementation for an example UE apparatus.
FIG. 28 is a diagram illustrating a hardware implementation for one or more example network entities.

DETAILED DESCRIPTION

FIG. 1 illustrates a diagram 100 of a wireless communications system associated with a plurality of cells 190. The wireless communications system includes user equipments (UEs) 102 and base stations/network entities 104. Some base stations may include an aggregated base station architecture and other base stations may include a disaggregated base station architecture. The aggregated base station architecture includes a radio unit (RU) 106, a distributed unit (DU) 108, and a centralized unit (CU) 110 that are configured to utilize a radio protocol stack that is physically or logically integrated within a single radio access network (RAN) node. A disaggregated base station architecture utilizes a protocol stack that is physically or logically distributed among two or more units (e.g., RUs 106, DUs 108, CUs 110) . For example, a CU 110 is implemented within a RAN node, and one or more DUs 108 may be co-located with the CU 110, or alternatively, may be geographically or virtually distributed throughout one or multiple other RAN nodes. The DUs 108 may be implemented to communicate with one or more RUs 106. Each of the RU 106, the DU 108 and the CU 110 can be implemented as virtual units, such as a virtual radio unit (VRU) , a virtual distributed unit (VDU) , or a virtual central unit (VCU) . The base station/network entity 104 (e.g., an aggregated base station or disaggregated units of the base station, such as the RU 106, the DU 108, or the CU 110) , may be referred to as a transmission reception point (TRP) .
Operations of the base station 104 and/or network designs may be based on aggregation characteristics of base station functionality. For example, disaggregated base station architectures are utilized in an integrated access backhaul (IAB) network, an open-radio access network (O-RAN) network, or a virtualized radio access network (vRAN) , which may also be referred to a cloud radio access network (C-RAN) . Disaggregation may include distributing functionality across the two or more units at various physical locations, as well as distributing functionality for at least one unit virtually, which can enable flexibility in network designs. The various units of the disaggregated base station architecture, or the disaggregated RAN architecture, can be configured for wired or wireless communication with at least one other unit. For example, the base stations 104a/104e and/or the RUs 106a-106d may communicate with the UEs 102a-102d and 102s via one or more radio frequency (RF) access links based on a Uu interface. In examples, multiple RUs 106 and/or base stations 104 may simultaneously serve the UEs 102, such as by intra-cell and/or inter-cell access links between the UEs 102 and the RUs 106/base stations 104.
The RU 106, the DU 108, and the CU 110 may include (or may be coupled to) one or more interfaces configured to transmit or receive information/signals via a wired or wireless transmission medium. A base station 104 or any of the one or more disaggregated base station units can be configured to communicate with one or more other base stations 104 or one or more other disaggregated base station units via the wired or wireless transmission medium. In examples, a processor, a memory, and/or a controller associated with executable instructions for the interfaces can be configured to provide communication between the base stations 104 and/or the one or more disaggregated base station units via the wired or wireless transmission medium. For example, a wired interface can be configured to transmit or receive the information/signals over a wired transmission medium, such as via the fronthaul link 160 between the RU 106d and the baseband unit (BBU) 112 of the base station 104d associated with the cell 190d. The BBU 112 includes a DU 108 and a CU 110, which may also have a wired interface (e.g., midhaul link) configured between the DU 108 and the CU 110 to transmit or receive the information/signals between the DU 108d and the CU 110d. In further examples, a wireless interface, which may include a receiver, a transmitter, or a transceiver, such as an RF transceiver, configured to transmit and/or receive the information/signals via the wireless transmission medium, such as for information communicated between the RU 106a of the cell 190a and the base station 104e of the cell 190e via cross-cell communication beams 136-138 of the RU 106a and the base station 104e.
The RUs 106 may be configured to implement lower layer functionality. For example, the RU 106 is controlled by the DU 108 and may correspond to a logical node that hosts RF processing functions, or lower layer PHY functionality, such as execution of fast Fourier transform (FFT) , inverse FFT (iFFT) , digital beamforming, physical random access channel (PRACH) extraction and filtering, etc. The functionality of the RU 106 may be based on the functional split, such as a functional split of lower layers.
The RUs 106 may transmit or receive over-the-air (OTA) communication with one or more UEs 102. For example, the RU 106b of the cell 190b communicates with the UE 102b of the cell 190b via a first set of communication beams 132 of the RU 106b and a second set of communication beams 134b of the UE 102b, which may correspond to inter-cell communication beams or, in some examples, cross-cell communication beams. For instance, the UE 102b of the cell 190b may communicate with the RU 106a of the cell 190a via a third set of communication beams 134a of the UE 102b and a fourth set of communication beams 136 of the RU 106a. Both real-time and non-real-time features of control plane and user plane communications of the RUs 106 can be controlled by associated DUs 108.
Any combination of the RU 106, the DU 108, and the CU 110, or reference thereto individually, may correspond to a base station 104. Thus, the base station 104 may include at least one of the RU 106, the DU 108, or the CU 110. The base stations 104 provide the UEs 102 with access to a core network. The base stations 104 might relay communications between the UEs 102 and the core network. The base stations 104 may be associated with macrocells for high-power cellular base stations and/or small cells for low-power cellular base stations. For example, the cell 190e may correspond to a macrocell, whereas the cells 190a-190d may correspond to small cells. Small cells include femtocells, picocells, microcells, etc. A cell structure that includes at least one macrocell and at least one small cell may be referred to as a “heterogeneous network. ”
Transmissions from a UE 102 to a base station 104/RU 106 are referred to as uplink (UL) transmissions, whereas transmissions from the base station 104/RU 106 to the UE 102 are referred to as downlink (DL) transmissions. Uplink transmissions may also be referred to as reverse link transmissions and downlink transmissions may also be referred to as forward link transmissions. For example, the RU 106d utilizes antennas 114 of the base station 104d of cell 190d to transmit a downlink/forward link communication to the UE 102d or receive an uplink/reverse link communication from the UE 102d based on the Uu interface associated with the access link between the UE 102d and the base station 104d/RU 106d.
Communication links between the UEs 102 and the base stations 104/RUs 106 may be based on multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be associated with one or more carriers. The UEs 102 and the base stations 104/RUs 106 may utilize a spectrum bandwidth of Y MHz (e.g., 5, 10, 15, 20, 100, 400, 800, 1600, 2000, etc. MHz) per carrier allocated in a carrier aggregation of up to a total of Yx MHz, where x component carriers (CCs) are used for communication in each of the uplink and downlink directions. The carriers may or may not be adjacent to each other along a frequency spectrum. In examples, uplink and downlink carriers may be allocated in an asymmetric manner, more or fewer carriers may be allocated to either the uplink or the downlink. A primary component carrier and one or more secondary component carriers may be included in the component carriers. The primary component carrier may be associated with a primary cell (PCell) and a secondary component carrier may be associated with as a secondary cell (SCell) .
Some UEs 102, such as the UEs 102a and 102s, may perform device-to-device (D2D) communications over sidelink. For example, a sidelink communication/D2D link utilizes a spectrum for a wireless wide area network (WWAN) associated with uplink and downlink communications. The sidelink communication/D2D link may also use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH) , a physical sidelink discovery channel (PSDCH) , a physical sidelink shared channel (PSSCH) , and/or a physical sidelink control channel (PSCCH) , to communicate information between UEs 102a and 102s. Such sidelink/D2D communication may be performed through various wireless communications systems, such as wireless fidelity (Wi-Fi) systems, Bluetooth systems, Long Term Evolution (LTE) systems, New Radio (NR) systems, etc.
The electromagnetic spectrum is often subdivided into different classes, bands, channels, etc., based on different frequencies/wavelengths associated with the electromagnetic spectrum. Fifth-generation (5G) NR is generally associated with two operating frequency ranges (FRs) referred to as frequency range 1 (FR1) and frequency range 2 (FR2) . FR1 ranges from 410 MHz –7.125 GHz and FR2 ranges from 24.25 GHz –71.0 GHz, which includes FR2-1 (24.25 GHz –52.6 GHz) and FR2-2 (52.6 GHz –71.0 GHz) . Although a portion of FR1 is actually greater than 6 GHz, FR1 is often referred to as the “sub-6 GHz” band. In contrast, FR2 is often referred to as the “millimeter wave” (mmW) band. FR2 is different from, but a near subset of, the “extremely high frequency” (EHF) band, which ranges from 30 GHz –300 GHz and is sometimes also referred to as a “millimeter wave” band. Frequencies between FR1 and FR2 are often referred to as “mid-band” frequencies. The operating band for the mid-band frequencies may be referred to as frequency range 3 (FR3) , which ranges 7.125 GHz –24.25 GHz. Frequency bands within FR3 may include characteristics of FR1 and/or FR2. Hence, features of FR1 and/or FR2 may be extended into the mid-band frequencies. Higher operating frequency bands have been identified to extend 5G NR communications above 52.6 GHz associated with the upper limit of FR2. Three of these higher operating frequency bands include FR2-2, which ranges from 52.6 GHz –71.0 GHz, FR4, which ranges from 71.0 GHz –114.25 GHz, and FR5, which ranges from 114.25 GHz –300 GHz. The upper limit of FR5 corresponds to the upper limit of the EHF band. Thus, unless otherwise specifically stated herein, the term “sub-6 GHz” may refer to frequencies that are less than 6 GHz, within FR1, or may include the mid-band frequencies. Further, unless otherwise specifically stated herein, the term “millimeter wave” , or mmW, refers to frequencies that may include the mid-band frequencies, may be within FR2-1, FR4, FR2-2, and/or FR5, or may be within the EHF band.
The UEs 102 and the base stations 104/RUs 106 may each include a plurality of antennas. The plurality of antennas may correspond to antenna elements, antenna panels, and/or antenna arrays that may facilitate beamforming operations. For example, the RU 106b transmits a downlink beamformed signal based on a first set of communication beams 132 to the UE 102b in one or more transmit directions of the RU 106b. The UE 102b may receive the downlink beamformed signal based on a second set of communication beams 134b from the RU 106b in one or more receive directions of the UE 102b. In a further example, the UE 102b may also transmit an uplink beamformed signal to the RU 106b based on the second set of communication beams 134b in one or more transmit directions of the UE 102b. The RU 106b may receive the uplink beamformed signal from the UE 102b in one or more receive directions of the RU 106b.
The UE 102b may perform beam training to determine the best receive and transmit directions for the beamformed signals. The transmit and receive directions for the UEs 102 and the base stations 104/RUs 106 might or might not be the same. In further examples, beamformed signals may be communicated between a first base station/RU 106a and a second base station 104e. For instance, the base station 104e of the cell 190e may transmit a beamformed signal to the RU 106a based on the communication beams 138 in one or more transmit directions of the base station 104e. The RU 106a may receive the beamformed signal from the base station 104e of the cell 190e based on the RU communication beams 136 in one or more receive directions of the RU 106a. In further examples, the base station 104e transmits a downlink beamformed signal to the UE 102e based on the communication beams 138 in one or more transmit directions of the base station 104e. The UE 102e receives the downlink beamformed signal from the base station 104e based on UE communication beams 130 in one or more receive directions of the UE 102e. The UE 102e may also transmit an uplink beamformed signal to the base station 104e based on the UE communication beams 130 in one or more transmit directions of the UE 102e, such that the base station 104e may receive the uplink beamformed signal from the UE 102e in one or more receive directions of the base station 104e.
The base station 104 may include and/or be referred to as a network entity. That is, “network entity” may refer to the base station 104 or at least one unit of the base station 104, such as the RU 106, the DU 108, and/or the CU 110. The base station 104 may also include and/or be referred to as a next generation evolved Node B (ng-eNB) , a generation NB (gNB) , an evolved NB (eNB) , an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , a TRP, a network node, network equipment, or other related terminology. The base station 104 or an entity at the base station 104 can be implemented as an IAB node, a relay node, a sidelink node, an aggregated (monolithic) base station with an RU 106 and a BBU 112 that includes a DU 108 and a CU 110, or as a disaggregated base station including one or more RUs 106, DUs 108, and/or CUs 110. A set of aggregated or disaggregated base stations may be referred to as a next generation-radio access network (NG-RAN) . In some examples, the UE 102a operates in dual connectivity (DC) with the base station 104e and the base station/RU 106a. In such cases, the base station 104e can be a master node and the base station/RU 160a can be a secondary node.
Uplink/downlink signaling may also be communicated via a satellite positioning system (SPS) 114. In an example, the SPS 114 of the cell 190c may be in communication with one or more UEs 102, such as the UE 102c, and one or more base stations 104/RUs 106, such as the RU 106c. The SPS 114 may correspond to one or more of a Global Navigation Satellite System (GNSS) , a global position system (GPS) , a non-terrestrial network (NTN) , or other satellite position/location system. The SPS 114 may be associated with LTE signals, NR signals (e.g., based on round trip time (RTT) and/or multi-RTT) , wireless local area network (WLAN) signals, a terrestrial beacon system (TBS) , sensor-based information, NR enhanced cell ID (NR E-CID) techniques, downlink angle-of-departure (DL-AoD) , downlink time difference of arrival (DL-TDOA) , uplink time difference of arrival (UL-TDOA) , uplink angle-of-arrival (UL-AoA) , and/or other systems, signals, or sensors.
Still referring to FIG. 1, in certain aspects, any of the UEs 102 may include a beamforming weight component 140 configured to quantize beamforming weights based on measured quality of one or more downlink reference signals, RSs, emitted by a network entity, NE, using a plurality of antenna ports. The beamforming weight component 140 is further configured to send, to the NE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports.
In certain aspects, any of the base stations 104 or a network entity of the base stations 104 may include a report configuration component 150 configured to configure a beamforming weight report associated with one or more reference signals, RSs. The report configuration component 150 is further configured to receive, from a user equipment, the beamforming weight report including beamforming weights based on a measured quality of the one or more RSs.
Accordingly, FIG. 1 describes a wireless communication system that may be implemented in connection with aspects of one or more other figures described herein, such as aspects illustrated in FIGs. 2-28. Further, although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as 5G-Advanced and future versions, LTE, LTE-advanced (LTE-A) , and other wireless technologies, such as 6G.
FIG. 2 is a bock diagram 200 illustrating an example of addressing problems in codebook-based beamforming. The network entity 104 may maintain a plurality of beams. The network entity applies different beams to different downlink reference signals, e.g., Synchronization Signal Blocks (SSBs) or Channel State Information Reference Signals (CSI-RSs) , for beam measurement. In conventional code-book based beamforming, the UE 102 measures the Layer 1 Reference Signal Receiving Power (L1-RSRP) or Layer 1 Signal-to-Interference plus Noise Ratio (L1-SINR) for each SSB/CSI-RS to identify the best network beam. However, for the codebook-based beamforming, the number of beams is always limited. Thus, the beam codebook may not always be able to cover the best direction for the UE. For example, as illustrated in FIG. 2, the network entity 104 maintains a plurality of beams 210, however, the best direction 220 for the UE is between two of the plurality of beams 210. Thus, the plurality of beams 210 from the beam codebook are not able to cover the best direction 220 for the UE 102.
In some examples, the network entity 104 and the UE 102 use channel-based beamforming to improve the performance. The network entity 104 and the UE 102 may perform channel-based beamforming by obtaining the raw channel. The raw channel indicates the channel without beamforming from the network entity. For example, raw channel estimate refers to the data that is recovered in channel estimation based on a known downlink reference signal from one or more than one antenna element (s) in the network entity. If the UE or the network entity is able to obtain the raw channel, the UE or the network entity can identify the best UE beam and the best network entity beam based on the eigenvector of the raw channel as follows.
USV^H=H^HH,
where, H indicates the raw channel between the network entity and the UE with the dimension of N_Rx×N_Tx; N_Rx is the number of receiving antenna ports in UE side and N_Tx is the number of transmission antenna ports in network entity side. Then the best network beam can be derived as the first M_p rows in matrix V, where M_p indicates the maximum number of antenna ports for transmission for one downlink signal.
The best UE beam can be derived as the first Q_p rows in matrixwhere Q_p indicates the maximum number of antenna ports for reception for one downlink signal, and the channel eigenvectoris calculated as follows:
The channel-based beamforming can provide significant gain, e.g., more than 5 dB L1-RSRP gain, compared to codebook-based beamforming. The network entity can transmit a downlink signal from up to M_p antenna ports, where M_p is much smaller than the total number of antenna ports N_p in the network entity. It is challenging for the network entity to obtain the raw channel or eigenvector for the raw channel for the channel-based beamforming.
This disclosure provides a framework for the channel-based beamforming, including: control signaling for the channel-based beamforming, downlink reference signal for beamforming weight measurement with symbol-level antenna or antenna port switching, and feedback for the beamforming weight. In this way, the beam management can be based on the channel-based beamforming, which can identify a better network beam compared to the codebook-based beamforming, thereby improving the system performance.
In some examples, the network entity and the UE use a multi-port reference signal (RS) based beamforming weight measurement and report in the channel-based beamforming. In some examples, the network entity and the UE use multi-resource RSs based beamforming weight measurement and report in the channel-based beamforming. Both the multi-port reference signal (RS) and the multi-resource RS based beamforming weight measurement and report will be discussed below.
FIG. 3 is a signaling diagram 300 illustrating an example of communications between a UE 102 and a network entity 104 for the multi-port RS based beamforming weight measurement and report. The network entity 104 may correspond to a base station or a unit of a base station, such as the RU 106, the DU 108, the CU 110, etc. Referring to FIG. 3, the UE 102 may send 303 a UE capability report indicating the UE capability indicating whether it supports the multi-port RS based beamforming weight measurement and report. In one example, the UE 102 transmits the UE capability on multi-port RS based beamforming weight measurement and report indicating at least one of: whether the UE supports multi-port RS based beamforming weight measurement and report; the maximum number of configured multi-port RS resources per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination and/or across all the bands; the maximum number of multi-port RS resources in a slot per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination and/or across all the bands; the number of ports for the multi-port RS. The UE may report the UE capability per feature set, per band, per band combination, or across all the bands.
In addition, the network entity 104 may obtain the UE capability from another network entity 104 or a core network (e.g., Access and Mobility Management Function (AMF) ) .
Based on the UE capability, the network entity 104 transmits 304 a first control signaling, e.g., RRC signaling (RRCReconfiguration) , configuring at least one beamforming weight report based on at least one multi-port RS. The network entity 104 may transmit 304 a control signal configuring the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule. For a certain type of beamforming weight report, e.g., semi-persistent or aperiodic beamforming weight report, and/or a certain type of multi-port RS, e.g., semi-persistent or aperiodic multi-port RS, the network entity 104 may transmit 306 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the at least one multi-port RS for beamforming weight measurement and report. For example, to trigger the beamforming weight report, the second control signaling can indicate the report ID of the beamforming weight report, and the UE 102 can identify the time/frequency resource for the uplink signal for the beamforming weight report. For example, to trigger the at least one multi-port RS, the second control signaling can indicate at least one multi-port RS resource index, and the UE can identify the location of the at least one multi-port RS resource, e.g., time/frequency resource for the at least one multi-port RS. Then the network entity 104 transmits 308 the at least one multi-port RS on the configured at least one multi-port RS resource. In one example, the multi-port RS is a CSI-RS.
The UE 102 measures the at least one multi-port RS. The UE 102 quantizes 310 the beamforming weights based on measured quality of the at least one multi-port RS.The UE 102 quantizes the beamforming weights based on the received first and/or second control signaling. For example, the beamforming weights are associated with a floating-point matrix calculated from the measured quality of the at least one multi-port RS. As an example, the beamforming weights form eigenvectors of the floating-point matrix. For example, the beamforming weights are based on the floating-point matrix. The UE 102 quantizes the floating-point matrix by one or more fixed-point indicators for the beamforming weight report. In one example, the UE may report every coefficient in the floating-point matrix by a 3-bit indicator for amplitude indication and a 2-bit indicator for angle indication. In another example, the UE only reports the top-N coefficients. Then the UE may additionally report another indicator to indicate the location for the reported N coefficients. The details of the beamforming weight report will be discussed below in connection with FIGs. 13-17.
The network entity identifies 314 the beamforming weight based on the configurations in the first and/or second control signaling. The UE behavior and the network entity behavior for multi-port RS based beamforming weight measurement and report will be discussed below in FIG. 4 and FIG. 5, respectively.
In this disclosure, unless otherwise specified, a RRC signaling may indicate an RRC reconfiguration message from the network entity to the UE, or a System Information Block (SIB) , where the SIB can be an existing SIB (e.g., SIB1) or a new SIB (e.g., SIB J, where J is an integer above 21) transmitted by network entity.
FIG. 4 is a block diagram 400 illustrating an example of UE behavior for the multi-port RS based beamforming weight measurement and report. Referring to FIG. 4, the UE 102 may transmit 403 UE capability on multi-port RS based beamforming weight measurement and report
The UE 102 may receive 404 a first control signaling, e.g., RRC signaling (RRCReconfiguration) , configuring at least a beam-forming weight report based on at least one multi-port RS. The UE 102 may receive 304 a control signal configuring the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule.
For a certain type of beamforming weight report, e.g., semi-persistent or aperiodic beamforming weight report, and/or a certain type of multi-port RS, e.g., semi-persistent or aperiodic multi-port RS, the UE may receive 406 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the configured multi-port RS for beamforming weight measurement and report. In one example, the multi-port RS is a CSI-RS. Then the UE receives 408 the at least one multi-port RS for beamforming weight measurement and report.
The UE 102 measures and quantizes 410 the beamforming weight based on the at least one multi-port RS and the received first and/or second control signaling. The UE 102 transmits 412 the beamforming weight report to the network entity.
FIG. 5 is a block diagram illustrating an example of network entity behavior for multi-port RS based beamforming weight measurement and report. Referring to FIG. 5, the network entity 104 may receive 503 UE capability on multi-port RS based beamforming weight measurement and report.
The network entity 104 transmits 504 a first control signaling, e.g., RRC signaling (RRCReconfiguration) , configuring at least a beam-forming weight report based on at least one multi-port RS. The network entity 104 may configure 504 the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule.
For a certain type of beamforming weight report, e.g., semi-persistent or aperiodic beamforming weight report, and/or a certain type of multi-port RS, e.g., semi-persistent or aperiodic multi-port RS, the network entity 104 may transmit 506 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the configured multi-port RS for beamforming weight measurement and report. In one example, the multi-port RS is a CSI-RS. Then the network entity 104 transmits 508 the at least one multi-port RS for beamforming weight measurement and report.
After the UE 102 measures and quantizes 410 the beamforming weight based on the at least one multi-port RS, the network entity 104 receives 512 the beamforming weight report from the UE.
FIG. 6 is a block diagram 600 illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report. The network entity 104 may transmit the multi-port RS with different structures of the multiple antenna ports with relevant control signaling. The multi-port RS may include multiple portions transmitted or emitted using the multiple antenna ports. In this disclosure, the terms “port” and “antenna port” are used interchangeably. In this disclosure, that the network entity transmits a port may refer to that the network entity transmits a portion of the multi-port RS using the port. In some examples, the network entity 104 transmits different portions of the multi-port RS of different port groups in different symbols, and the network entity multiplexes the portions of multi-port RS of the ports within a group in frequency domain multiplexing (FDM) manner. For example, the network entity 104 transmits different portions of the multi-port RS of different ports in an antenna port group in different subcarriers. As illustrated in FIG. 6, the network entity 104 transmits multiple portions of the multi-port RS by multiple port groups including group 1 (port 3000 and 3001) , group 2 (port 3002, 3003) , group 3 (port 3004, 3005) and group 4 (port 3006 and 3007) in multiple symbols. Each port group of the multiple port groups is in a symbol of the multiple symbols. The network entity 104 transmits different portions of the multi-port RS by port 3000 and 3001 in the port group 1 in different subcarriers.
The number of ports in a port group may be predefined or configured by the network entity by the first or second control signaling. The number of port (s) group may be predefined or configured by the network entity by the first or second control signaling.
In some implementations, the network entity 104 may configure the symbol and/or slot index for each port (s) group by the first and/or the second control signaling. In some other implementations, the network entity 104 may configure the starting symbol and/or slot index for each port (s) group by the first and/or second control signaling. The network entity 104 may further configure the symbol offset between each port (s) group. Alternatively, the symbol offset is predefined, e.g., different port (s) groups are multiplexed in consecutive symbols.
In some implementations, the network entity 104 may configure the bandwidth for the multi-port RS by the first or the second control signaling. In some other implementations, the bandwidth for the multi-port RS may be predefined, e.g., the same as the bandwidth for the bandwidth part.
In some implementations, the network entity 104 may configure the frequency domain density and/or the resource element (RE) offset for each port by the first and/or second control signaling. In some other implementations, the frequency domain density per port may be predefined, e.g., 3 REs per Resource Block (RB) . The RE offset for each port may be predefined, e.g., the RE offset is 0 for the even port and the RE offset is 2 for the odd port.
In some implementations, the network entity 104 may configure an SSB as the quasi-co-location (QCL) source for the multi-port RS by the first or the second control signaling. Then the UE 102 may identify the receiving beam for the multi-port RS based on the measurement of the SSB.
FIG. 7A and FIG. 7B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report. In this example, the network entity 104 transmits different portions of the multi-port RS from different port (s) groups in different symbols, and the network entity 104 multiplexes the portions of the multi-port RS from the ports within a group in code domain multiplexing (CDM) manner, e.g., the network entity transmits different portions of the multi-port RS from different ports in different group by different orthogonal cover codes (OCC) . Compared to the example discussed in connection with FIG. 6, the difference is that the network entity 104 transmits the portions of the multi-port RS from the ports within a group in the same subcarriers, but with different OCCs. The OCC code for each portion of the multi-port RS from each port may be predefined, e.g., [1, 1] for even port and [1, -1] for odd port. Then the UE 102 can distinguish different portions of the multi-port RS from different ports within a port group by applying different OCCs for de-spreading. As illustrated in FIG. 7A and FIG. 7B, the network entity 104 transmits multiple portions of the multi-port RS from multiple port groups including group 1 (port 3000 and 3001) , group 2 (port 3002, 3003) , group 3 (port 3004, 3005) and group 4 (port 3006 and 3007) in multiple symbols. Each port group of the multiple port groups is in a symbol of the multiple symbols. The network entity 104 transmits portions of the multi-port RS from the port 3000 and 3001 in the port group 1 in the same subcarriers, but with different OCCs. For example, the network entity 104 transmits portions of the multi-port RS from the port 3000 with OCC code “1” and the port 3001 with the OCC code “-1” in the same subcarriers.
FIG. 8A is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) in each symbol for phase tracking with up to 3 ports per symbol. FIG. 8B is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) in each symbol for phase tracking with up to 2 ports per symbol. In some examples, the network entity transmits different port (s) groups in different symbols, and the network entity multiplexes the ports within a group in frequency domain multiplexing (FDM) manner, e.g., the network entity transmits different ports in a group in different subcarriers. The network entity transmits at least one port for phase tracking in every symbol with the multi-port RS.
Referring to FIG. 8A, in this example, the network entity 104 transmits the TDM+FDM based multi-port RS in different port (s) groups in different symbols with one port (port 3000) in each symbol for phase tracking. As illustrated in FIG. 8A, the network entity is able to transmit 3 ports simultaneously.
Referring to FIG. 8B, in this example, the network entity 104 transmits the TDM+FDM based multi-port RS in different port (s) groups in different symbols with one port (port 3000) in each symbol for phase tracking. As illustrated in FIG. 8B, the network entity is able to transmit 3 ports simultaneously.
Referring to FIG. 8A and FIG. 8B, by using at least one port for phase tracking in every symbol with the multi-port RS, the UE 102 can compare the phase offset measured in this port and perform phase compensation for each antenna port group.
In some examples, the UE can calculate the channel from all the ports as follows:
where θ_j indicates the phase offset for port (s) group j with the phase in the phase port (s) group as reference, H_j indicates the measured channel for port (s) group j with the dimension of N_Rx×N_Tx, _g; N_Rx is the number of receiving antenna ports in UE side and N_Tx, _g is the number of transmission antenna ports in each port group.
In some implementations, the network entity transmits the at least one port for phase tracking as at least one of the ports in one port (s) group. In some other implementations, the network entity transmits the at least one port for phase tracking an independent port.
In some implementations, the network entity configures the frequency domain density, frequency offset, and/or time domain density for the at least one port for phase tracking by the first and/or second control signaling. In some other implementations, the frequency domain density, frequency offset, and/or time domain density for the at least one port for phase tracking is predefined.
FIG. 9A is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one additional port in each symbol for phase tracking with up to 3 ports per symbol. FIG. 9B is a block diagram illustrating an example of the TDM+FDM based multi-port RS for beamforming weight measurement and report with one additional port in each symbol for phase tracking with up to 2 ports per symbol. In some examples, the network entity transmits one additional port in each symbol for phase tracking.
Referring to FIG. 9A and FIG. 9B, the network entity 104 transmits the TDM+FDM based multi-port RS with one additional port (port 6000) in each symbol for phase tracking. As illustrated in FIG. 9A, the network entity is able to transmit 3 ports simultaneously. As illustrated in FIG. 9B, the network entity is able to transmit 2 ports simultaneously.
FIG. 10A and FIG. 10B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) without OCC in each symbol for phase tracking with up to 3 ports per symbol. FIG. 11A and FIG. 11B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) without OCC in each symbol for phase tracking with up to 2 ports per symbol. In some examples, the network entity 104 transmits different port (s) groups in different symbols, and the network entity 104 multiplexes the ports within a group in code domain multiplexing (CDM) manner, i.e., the network entity transmits different ports in different group by different orthogonal cover codes (OCC) . Compared to the examples discussed in connection with FIGs. 8A, 8B, 9A and 9B, the difference is that the network entity transmits the ports within a group in the same subcarriers, but with different OCCs. The OCC code for each port may be predefined, e.g., [1, 1] for even port and [1, -1] for odd port. Then the UE can distinguish different ports within a port (s) group by applying different OCCs for de-spreading. In addition, the UE 102 may transmit the at least one port for phase tracking with or without OCC.
Referring to FIGs. 10A, 10B, 11A, and 11B, the network entity 104 transmits the TDM+FDM based multi-port RS for beamforming weight measurement and report with one port (port 3000) without OCC in each symbol for phase tracking. As illustrated in FIG. 10A and FIG. 10B, the network entity 104 is able to transmit 3 ports simultaneously. As illustrated in FIG. 11A and FIG. 11B, the network entity 104 is able to transmit 2 ports simultaneously.
FIG. 12A and FIG. 12B are block diagrams illustrating an example of the TDM+CDM based multi-port RS for beamforming weight measurement and report with one additional port without OCC in each symbol for phase tracking. In this example, the network entity 104 transmits the TDM+FDM based multi-port RS with one additional port (port 6000) in each symbol for phase tracking.
In some examples, the network entity 104 configures the multiplexing scheme, e.g., FDM or CDM, for port (s) within a port (s) group by the first and/or the second control signaling. The network entity may configure the presence of the at least one port for phase tracking by the first and/or the second control signaling. Then the network entity may configure and transmit the multi-port RS based on the examples discussed in connection with FIGs. 7A-12B.
In some examples, the UE 102 reports the UE capability or UE assistance information indicating at least one of the parameters: the supported or preferred multiplexing scheme, e.g., FDM or CDM, for port (s) within a port (s) group; the supported or preferred number of ports for phase tracking. In one example, the UE may report it does not support the at least one port for phase tracking by reporting number of ports for phase tracking as 0 or by not reporting the number of ports for phase tracking.
In some examples, the UE 102 reports an indicator indicating the beamforming weight report based on the number of ports for the multi-port RS. For example, the beamforming weights are associated with a floating-point matrix calculated from the measured quality of the at least one multi-port RS. As an example, the beamforming weights form eigenvectors of the floating-point matrix. For example, the beamforming weights are based on the floating-point matrix. The UE 102 quantizes the floating-point matrix by one or more fixed-point indicators for the beamforming weight report. The UE 102 quantizes the floating-point matrix by one or more fixed-point indicators for the beamforming weight report.
In some implementations, the beamforming weight is associated with a matrix, for example, the floating-point matrix, with the dimension of N_Tx by 1 or 2, where N_Tx indicates the number of ports for the multi-port RS. In some other implementations, the beamforming weight is associated with a matrix with the dimension of N_Tx by N_Tx, _g, where N_Tx, _g is the maximum or minimum number of ports in a symbol for the multi-port RS. In some other implementations, the beamforming weight is associated with a matrix with the dimension of N_Tx by L, where L is configured by the first control signaling by the network entity.
FIG. 13 is a block diagram illustrating an example of partial antenna or antenna port measurement. In some examples, the beamforming weight could have more ports, e.g., more rows, than the number of ports for the multi-port RS. Referring to FIG. 13, the network entity only transmits the multi-port RS from a first subset (e.g., 1351) of antennas or antenna ports. The UE measures the multi-port RS from the first subset (e.g., 1351) of antennas or antenna ports. The UE does not measure the multi-port RS from a second subset (e.g., 1352) of antennas or antenna ports. The UE can perform spatial domain interpolation or prediction to estimate the channel from the second subset (e.g., 1352) of unmeasured antennas or antenna ports. Thus, the UE can predict the channel from all the antennas or all antenna ports (e.g., 1351 and 1352) with spatial domain interpolation or spatial domain prediction, e.g., spatial domain prediction with machine learning.
Then the network entity may configure the number of horizontal antenna ports and number of vertical antenna ports for the beamforming weight report by the first control signaling. The network entity may further configure the location of each antenna port for the multi-port RS in the full antenna port structure by the first and/or second control signaling. For example, the UE may report the UE capability indicating at least one of: the minimum number of measured antenna ports; the minimum number of measured horizontal antenna ports; the minimum number of measured vertical antenna ports; the preferred measured antenna port indexes in horizontal; the preferred measured antenna port indexes in vertical.
FIGs. 14-17 illustrate the details of different options of the beamforming weight report. In some examples, the UE send an explicit eigenvector report (e.g., FIGS. 14-16) . In some other examples, the UE sends a codebook-based eigenvector report (e.g., FIG. 17) .
For the explicit eigenvector report, the UE reports the eigenvector calculated based on the channel measured from the at least one multi-port RS. The UE measures the eigenvector based on the wideband channel estimated from the multi-port RS.
In some implementations, the network entity configures the number of columns L for the eigenvector report. In some other implementations, the number of columns L for the eigenvector report is predefined, e.g., L=1 or L=2. In some other implementations, the number of columns L for the eigenvector report is determined based on the number of ports within a port (s) group. The UE reports the first L columns for the eigenvector, which is defined as reported eigenvector.
FIG. 14 is a block diagram 1400 illustrating an example of the beamforming weight report with a full eigenvector report. In some implementations, the UE reports the amplitude and phase for each coefficient in the reported eigenvector. In some implementations, the network entity may configure the number of bits and step size for amplitude and/or phase quantization. In some other implementations, the number of bits and step size for the amplitude and/or phase quantization is predefined. In some implementations, the UE quantizes each coefficient based on the number of bits for amplitude quantization X1 and number of bits for phase quantization X2. In one example, the amplitude can be quantized as and the phase can be quantized as Then the UE can report the amplitude and phase for each coefficient to the network. In some other implementations, the UE reports the real and imaginary part for each coefficient in the reported eigenvector.
Referring to FIG. 14, the UE reports all coefficients of the first 2 columns for eigenvector measured from 8-port RS. The reported coefficients 1412 in the beamforming wight report include measured amplitudes 1451 and measured phases 1452 of all coefficients of the first 2 columns for eigenvector measured from 8-port RS.In one example, the UE may report every coefficient in the matrix by a 3-bit indicator for amplitude indication and a 2-bit indicator for angle indication.
FIG. 15 is a block diagram 1500 illustrating an example of beamforming weight report with a non-zero-power (NZP) coefficients only report. In some examples, the UE reports the NZP coefficients to the network entity only. The UE reports an indicator indicating the location of the NZP coefficients within the eigenvector to the network entity. In one example, for a reported eigenvector with the dimension of N_Tx×L, the UE reports a bitmap with the dimension of N_Tx×L, where bit x indicates whether the corresponding coefficient x in the reported eigenvector is reported or not.
Referring to FIG. 15, the UE reports NZP coefficients of the first 2 columns for eigenvector measured from 8-port RS. The reported coefficients 1512 in the beamforming wight report may include measured amplitudes 1551, measured phases 1552 of the NZP coefficients. The UE may further report the bitmap 1550 indicating indicates whether the corresponding coefficient in the reported eigenvector is reported or not.
FIG. 16 is a block diagram 1600 illustrating an example of beamforming weight report with a top-N strongest coefficients only report. In some examples, the network entity configures the maximum number of reported coefficients for a reported eigenvector by the first or the second control signaling. In some examples, the network entity configures the maximum number of reported coefficients per column for a reported eigenvector by the first or the second control signaling. Then the UE reports the strongest coefficients, i.e., coefficients with highest amplitude, to the network entity. The UE reports an indicator indicating the location of the strongest coefficients within the eigenvector to the network entity. In one example, for a reported eigenvector with the dimension of N_Tx×L, the UE reports a bitmap with the dimension of N_Tx×L, where bit x indicates whether the corresponding coefficient x in the reported eigenvector is reported or not.
Referring to FIG. 16, the UE reports N strongest coefficients of the first 2 columns for eigenvector measured from 8-port RS. As an example, the UE only reports the top-N coefficients. The number of the strongest coefficients can be any value. As illustrated in FIG. 16, the UE reports 8 strongest coefficients of the first 2 columns for eigenvector measured from 8-port RS. The reported coefficients 1612 in the beamforming wight report may include measured amplitudes 1651, measured phases 1652 of the N strongest coefficients. The UE may further report the bitmap 1650 indicating indicates whether the corresponding coefficient in the reported eigenvector is reported or not. Then the UE may additionally report another indicator to indicate the location for the reported N coefficients.
In some implementations, the UE may transmit the reported eigenvector by PUCCH or PUSCH. For long PUCCH or PUSCH, the UE may transmit the reported eigenvector in CSI part 1 or CSI part 2. Alternatively, the UE may transmit part of the reported eigenvector in CSI part 1, e.g., the indicator indicating the location of the NZP coefficients or strongest coefficients, and remaining part of the reported eigenvector in CSI part 2, e.g., amplitude and phase for each NZP or strong coefficient or real and imaginary part for each NZP or strong coefficient. In some other implementations, the UE may transmit the reported eigenvector by MAC CE.
FIG. 17 is a block diagram 1700 illustrating an example of beamforming weights grouping and a codebook subset restriction for a codebook-based eigenvector report. In some examples, the UE may report at least one beamforming weight from a beamforming weight codebook based on the channel measured from the at least one multi-port RS. The beamforming weight codebook may include a set of beamforming weights with different directions. The UE can identify one of the beamforming weights from the beamforming weight codebook for the channel measured from the at least one multi-port RS that can produce the strongest channel energy.
In some implementations, the network entity may configure the codebook subset restriction by the first and/or second control signaling. For example, the network entity may configure a subset set of beamforming weights from the beamforming weight codebook. Then the UE can search the beamforming weight from the configured subset of beamforming weights from the beamforming weight codebook.
In one example, the network entity may transmit a bitmap indicating whether each beam in the beamforming weight codebook is valid for report or not. In another example, the network entity may configure the groups for each beamforming weights in the beamforming weight codebook, and the network entity may configure the corresponding group index in the first and/or second control signaling to indicate the valid beamforming weights group for a UE to search the beamforming weight.
Referring to FIG. 17, the beamforming weight codebook may include the set of beamforming weights, for example, beamforming weights group 1721, beamforming weights group 1722. The network entity 104 may identify the coarse direction for the UE 102 based on a L1-RSRP report from SSBs with wide beams applied. For example, the coarse direction for the UE is indicated by the beam for SSB with strongest L1-RSRP 1762. The network entity 104 may configure a subset set of beamforming weights from the beamforming weight codebook, which corresponds to beamforming weights group 1722. Then the UE can search the beamforming weight from the configured subset (e.g., beamforming weights group 1722) of beamforming weights in the beamforming weight codebook. Then the network entity 104 can ask the UE 102 to search the corresponding beamforming weights (e.g., beamforming weights group 1722) around the coarse direction (e.g., beam for SSB with strongest L1-RSRP 1762) to identify the best beamforming weight (e.g., beamforming weigh 1732) . The UE can identify one of the beamforming weights from the codebook for the channel measured from the at least one multi-port RS that can produce the strongest channel energy.
In some examples, the beamforming weight codebook includes Q beamforming weights, and the beamforming weight is the same for each polarization without antenna combining cross polarizations. In one example, the beamforming weight codebook is defined as follows, where for dual-column case, the first half of rows are for the first polarization and the second half of rows are for the second polarization
B= [b₁ b₂ … b_Q] .
For single-column based report,
b_l=q_m, _n
For dual-column based report,
where, denotes Kronecker product. Different beams are generated based on different value of m and/or n. In some implementations, the network entity configures the number of horizontal antenna ports (N1) , number of horizontal oversampling factor (O1) , number of horizontal antenna ports (N2) , and number of horizontal oversampling factor (O2) by the first control signaling or the second control signaling. In some other implementations, some parameters may be predefined, e.g., O1 = O2 = 1.
In some examples, the beamforming weight codebook includes Q beamforming weights, and the beamforming weight can be different for different polarization without antenna combining cross polarizations. In one example, the beamforming weight codebook is defined as follows, where for dual-column case, the first half of rows are for the first polarization and the second half of rows are for the second polarization.
B= [b₁ b₂ … b_Q] ,
For single-column based report,
b_l=q_m, _n
For dual-column based report,
where, denotes Kronecker product. Different beams are generated based on at least one different value of m, n, m’a nd n’ . In some implementations, the network entity configures the number of horizontal antenna ports (N1) , number of horizontal oversampling factor (O1) , number of horizontal antenna ports (N2) , and number of horizontal oversampling factor (O2) by the first control signaling or the second control signaling. In some other implementations, some parameters may be predefined, e.g., O1 = O2 = 1.
In some examples, the beamforming weight codebook includes Q beamforming weights, and the beamforming weight is generated based on a common beamforming weight in each polarization with cross-polarization combining. In one example, the beamforming weight codebook is defined as follows, where the first half of rows are for the first polarization and the second half of rows are for the second polarization.
B= [b₁ b₂ … b_Q]
For single-column based report,
For dual-column based report,
where, denotes Kronecker product. Different beams are generated based on at least one different value of m, n, m’ , n’ , k and k’ . In some implementations, the network entity configures the number of horizontal antenna ports (N1) , number of horizontal oversampling factor (O1) , number of horizontal antenna ports (N2) , number of horizontal oversampling factor (O2) , and polarization combining oversampling factor (O3) by the first control signaling or the second control signaling. In some other implementations, some parameters may be predefined, e.g., O1 = O2 = O3 = 1.
In some examples, the beamforming weight codebook includes Q beamforming weights, and the beamforming weight is generated based on a common beamforming weight in each polarization with cross-polarization combining. In one example, the beamforming weight codebook is defined as follows, where the first half of rows are for the first polarization and the second half of rows are for the second polarization.
B= [b₁ b₂ …b_Q]
For single-column based report,
For dual-column based report,
where, denotes Kronecker product. Different beams are generated based on at least one different value of m, n, m’ , n’ , m” , n” , m”’ , n”’ , k and k’ . In some implementations, the network entity configures the number of horizontal antenna ports (N1) , number of horizontal oversampling factor (O1) , number of horizontal antenna ports (N2) , number of horizontal oversampling factor (O2) , and polarization combining oversampling factor (O3) by the first control signaling or the second control signaling. In some other implementations, some parameters may be predefined, e.g., O1 = O2 = O3 = 1.
In some examples, the network entity configures whether the beamforming weight codebook is generated based on polarization-common or polarization-specific beamforming weights and/or whether the beamforming weight codebook is generated with or without cross-polarization combining. Then the UE can report the beamforming weight index from the beamforming weight codebook based on the examples discussed above.
In some examples, the UE reports the UE capability or UE assist information indicating the supported or preferred beamforming weight codebook structure, i.e., whether the beamforming weight codebook is generated based on polarization-common or polarization-specific beamforming weights and/or whether the beamforming weight codebook is generated with or without cross-polarization combining. Then the network entity may further configure the UE to report the beamforming weight index from the corresponding beamforming weight codebook based on the examples discussed above.
In some implementations, the UE may transmit the beamforming weight index by PUCCH or PUSCH. For long PUCCH or PUSCH, the UE may transmit the beamforming weight index in CSI part 1 or CSI part 2. In some implementations, the UE may transmit the beamforming weight index by MAC CE. The UE reports at least one beamforming weights from a beamforming weight codebook and a beam combining vector based on the channel measured from the at least one multi-port RS. Compared to the examples discussed above, the difference is that in this option, the UE reports at least one beam index based on the dual-column beams in the beamforming weight codebook above, and reports a beam combining vector for the reported beams.
The UE can calculate the beam combining vector W2 as follows:
where W1 is the selected beam (s) from the beamforming weight codebook, and V is the first L, e.g., L=1 or 2, rows of the eigenvector of the channel measured from the at least one multi-port RS.
In some implementations, the network entity configures the number of selected beams N3 by the first or second control signaling. In some other implementations, the UE selects the number of selected beams N3 and reports the number of selected beams. Then the dimension of W2 is N3 by L. The UE may report the W2 based on the similar methods for eigenvector report as discussed above
In some implementations, the UE transmits the beamforming weight indexes and beam combining vector by PUCCH or PUSCH. For long PUCCH or PUSCH, the UE may transmit the beamforming weight indexes and beam combining vector in CSI part 1 or CSI part 2. Alternatively, the UE may transmit the beamforming weight index (es) in CSI part 1, and the beam combining vector in CSI part 2. Alternatively, the UE may transmit the beamforming weight index (es) and part of beam combining vector in CSI part 1, and remaining part of the beam combining vector in CSI part 2, e.g., the indicator indicating the location of the NZP coefficients or strongest coefficients for beam combining vector in CSI part 1, and remaining part of the beam combining vector in CSI part 2, e.g., amplitude and phase for each NZP or strong coefficient or real and imaginary part for each NZP or strong coefficient. In some other implementations, the UE may transmit the beamforming weight indexes and beam combining vector by MAC CE.
In some examples, the network entity may configure whether the UE should report the full reported eigenvector, or beamforming weight index, or beamforming weight index (es) and beam combining vector by the first or the second control signaling. Then the UE can report the beamforming weight based on the corresponding examples.
In some examples, the UE may report the UE capability or UE assistance information indicating whether the UE supports or prefers to report the full reported eigenvector, or beamforming weight index, or beamforming weight index (es) and beam combining vector by the first or the second control signaling. Then the network entity can configure the beamforming weight report based on the corresponding examples discussed above.
In some examples, in addition to the reported eigenvector, the network entity may configure the UE to report the L1-RSRP or L1-SINR measured based on the reported eigenvector. In some implementations, the UE may report the L1-RSRP or L1-SINR and the eigenvector jointly by PUCCH or PUSCH or MAC CE. In some other implementations, the UE may report the L1-RSRP or L1-SINR and the eigenvector separately by separate PUCCH or PUSCH or MAC CE. In some examples, the network entity and the UE use a multi-port RS based beamforming weight measurement and report in the channel-based beamforming, as discussed above in connection with FIGs. 3-13. In some examples, the network entity and the UE use multi-resource RSs based beamforming weight measurement and report in the channel-based beamforming, which will be discussed in in connection with FIGs. 18-24 below.
FIG. 18 is a signaling diagram illustrating an example of communications between a UE 102 and a network entity 104 for multi-resource RSs based beamforming weight measurement and report. Compared to the multi-port RS based beamforming weight measurement and report discussed above in connection with FIGs. 3-13, the difference is in the multi-resource RSs based beamforming weight measurement and report, the UE 102 measures the beamforming weight based on a set of RS resources, e.g., a set of CSI-RS resources, instead of a multi-port RS. The network entity 104 may configure the multi-resource RSs with the same bandwidth, and transmit different RS resources in different symbols with different antenna port. The UE can construct the channel from all the antenna ports based on the set of RS resources. Then the UE can measure and report the eigenvector based on the constructed channel.
Referring to FIG. 18, the UE 102 may send 1803 the UE capability indicating whether it supports the multi-resource RSs based beamforming weight measurement and report. In one example, the UE 102 transmits the UE capability on the multi-resource RSs based beamforming weight measurement and report indicating at least one of: whether the UE supports multi-resource RS based beamforming weight measurement and report; the maximum number of configured sets of multi-resource RS per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination and/or per UE; the maximum number of RS resources in a slot per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination and/or per UE; the number of resources per resource set for the multi-resource RS. The UE may report the UE capability per feature set, per band, per band combination, or per UE. In addition, the network entity 104 may obtain the UE capability from another network entity 104 or a core network (e.g., Access and Mobility Management Function (AMF) ) .
Based on the UE capability, the network entity 104 transmits 1804 a first control signaling, e.g., RRC signaling (RRCReconfiguration) , configuring at least one beamforming weight report based on at least one set of RS resources. The network entity 104 may transmit 1804 a control signal configuring the beamforming weight report to include the at least one set of beamforming weights selected based on a predetermined rule. For a certain type of beamforming weight report, e.g., semi-persistent or aperiodic beamforming weight report, and/or a certain type of multi-port RS, e.g., semi-persistent or aperiodic multi-port RS, the network entity 104 may transmit 1806 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the at least one set of RS resources for beamforming weight measurement and report. For example, to trigger the beamforming weight report, the second control signaling can indicate the report ID of the beamforming weight report, and the UE 102 can identify the time/frequency resource for the uplink signal for the beamforming weight report. For example, to trigger the at least one set of RS resources, the second control signaling can indicate at least one set of RS resources indexes, and the UE can identify the location of the at least one set of RS resources, e.g., time/frequency resource for the at least one set of RS resources. Then the network entity 104 transmits 1808 the at least at least one set of RSs on the configured at least one set of RS resources. In one example, the at least one set of RSs are CSI-RSs.
The UE 102 measures the at least one set of RSs. The UE 102 quantizes 1810 the beamforming weight based on measured quality of the at least one set of RSs. The UE 102 quantizes the beamforming weight based on the received first and/or second control signaling.
The UE 102 sends 1812 the beamforming weight report to the network entity. The network entity identifies 1814 the beamforming weight based on the configurations in the first and/or second control signaling. The UE behavior and the network entity behavior for the multi-resource RSs based beamforming weight measurement and report will be discussed below in FIG. 19 and FIG. 20, respectively.
FIG. 19 is a block diagram 1900 illustrating an example of UE behavior for the multi-resource RSs based beamforming weight measurement and report. Referring to FIG. 19, the UE 102 may transmit 1903 UE capability on the multi-resource RSs based beamforming weight measurement and report
The UE 102 may receive 1904 a first control signaling, e.g., RRC signaling (RRCReconfiguration) , configuring at least one beam-forming weight report based on at least one set of RS resources. The UE 102 may receive 1904 a control signal configuring the beamforming weight report to include the at least one set of beamforming weights selected based on a predetermined rule.
For a certain type of beamforming weight report, e.g., semi-persistent or aperiodic beamforming weight report, and/or a certain type of multi-port RS, e.g., semi-persistent or aperiodic multi-port RS, the UE may receive 1906 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the at least one set of RS resources for beamforming weight measurement and report. In one example, the at least one set of RS resources are CSI-RS resources. Then the UE receives 1908 the at least one set of RS resources for beamforming weight measurement and report.
The UE 102 measures and quantizes 1910 the beamforming weight based on the at least one set of RS resources and the received first and/or second control signaling. The UE 102 transmits 1912 the beamforming weight report to the network entity.
FIG. 20 is a block diagram 2000 illustrating an example of network entity behavior for the multi-resource RSs based beamforming weight measurement and report. Referring to FIG. 20, the network entity 104 may receive 2003 UE capability on the multi-resource RSs based beamforming weight measurement and report.
The network entity 104 transmits 2004 a first control signaling, e.g., RRC signaling (RRCReconfiguration) , configuring at least a beam-forming weight report based on at least one set of RS resources. The network entity 104 may configure 2004 the beamforming weight report to include the at least one set of beamforming weights selected based on a predetermined rule.
For a certain type of beamforming weight report, e.g., semi-persistent or aperiodic beamforming weight report, and/or a certain type of multi-port RS, e.g., semi-persistent or aperiodic multi-port RS, the network entity 104 may transmit 2006 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the at least one set of RS resources for beamforming weight measurement and report. In one example, the at least one set of RS resources are CSI-RS resources. Then the network entity 104 transmits 2008 the at least one set of RSs on the at least one set of RS resources for beamforming weight measurement and report. Then, the network entity 104 receives 2012 the beamforming weight report from the UE.
FIG. 21 is a block diagram illustrating an example of the multi-resource RSs with full antenna or antenna port switching. The network entity 104 may transmit the multi-resource RSs with different structures and relevant control signaling. The network entity may transmit the multi-resource RSs with antenna or antenna port switching. In some examples, the network entity 104 transmits the multi-resource RSs with fully antenna port switching across the resources. The network entity applies different antenna (s) or antenna port (s) in different resources. The network entity may configure whether a set of RS resources should be transmitted with antenna switching or not by the first or the second control signaling. The network entity may multiplex the signals from different ports within a resource in FDM manner, e.g., with different subcarriers for different ports, or CDM manner, e.g., with different OCC codes for different ports.
Referring to FIG. 21, the network entity 104 transmits an RS on resource 2101 from antennas or antenna ports 1 and 2, an RS on resource 2102 from antennas or antenna ports 3 and 4, an RS on resource 2103 from antennas or antenna ports 5 and 6 in resource 2101, and an RS on resource 2104 from antennas or antenna ports 7 and 8. The network entity may multiplex the RSs from different ports within a same resource in FDM manner, or CDM manner.
In some examples, the network entity configures the RS resources for antenna switching with at least one of the common configurations: frequency domain density, bandwidth, transmission power, number of ports, resource elements and so on. The network entity may configure a common value for the corresponding parameters for each resource. Alternatively, the network entity may configure a set of common parameters for the resource set.
In some implementations, the network entity configures the RS resources in consecutive symbols. In some other implementations, the network entity can configure the RS resources in non-consecutive symbols. The UE may further report the UE capability indicating the maximum offset between each symbol or the maximum time domain duration for the resource set with antenna switching.
FIG. 22 is a block diagram illustrating an example of the multi-resource RSs with partial antenna or antenna port switching. The network entity may transmit the multi-resource RSs with partial antenna or antenna port switching. The network entity may multiplex the RSs from different ports within a resource in FDM manner, e.g., with different subcarriers for different ports, or CDM manner, e.g., with different OCC codes for different ports.
Compared to the example illustrated in FIG. 21, the difference is that in this example, the network entity applies at least one antenna or antenna port across the resources. For the other antenna ports, the network entity applies different antenna (s) or antenna port (s) in different resources. Then the UE can perform phase tracking and compensation based on the at least one antenna port across resources. The UE may track phase of the plurality of RSs on the plurality of RS resources by receiving the plurality of RSs on the plurality of RS resources from the at least one antenna port of the plurality of antenna ports. The network entity may configure whether a set of RS resource (s) should be transmitted with partial antenna switching or not by the first or the second control signaling. The network entity may further configure the number of port (s) without antenna or antenna port switching across the resources.
Referring to FIG. 22, the network entity transmits all RSs across the set of RS resources (e.g., resource 2201, 2202, 2203, 2204, 2205, 2206, 2207) by at least one antenna or antenna port (e.g., antenna or antenna port 1) . The network entity applies at least one antenna or antenna port (e.g., antenna or antenna port 1) across the resources (e.g., resource 2201, 2202, 2203, 2204, 2205, 2206, 2207) . For the other antenna ports (e.g., antenna or antenna port 2, 3, 4, 5, 6, 7, 8) , the network entity applies different antenna (s) or antenna port (s) in different resources. Then the UE can perform phase tracking and compensation based on the at least one antenna port (e.g., antenna or antenna port 1) across resources (e.g., resource 2201, 2202, 2203, 2204, 2205, 2206, 2207) .
FIG. 23 is a block diagram illustrating an example of the multi-resource RSs transmission with antenna switching first. FIG. 24 is a block diagram illustrating an example of multi-resource RSs transmission with repetition first. In some examples, the network entity configures whether the network entity should transmit the multi-resource RSs with the full antenna port switching or partial antenna port switching by the first control signaling or the second control signaling. Then the network entity transmits the multi-resource RSs accordingly.
The network entity may configure the network entity to transmit the multi-resource RSs with antenna switching with repetitions. In some implementation, the network entity may configure the number of repetitions N_rep. Then the network entity may divide the resources into N_rep groups. Within each group, the network entity can transmit the multi-resource RSs with antenna switching. In some other implementations, the network entity configures the total number of antennas or antenna ports for antenna switching N_p, then the network entity can transmit resources with antenna switching, whereindicates the number of ports per resource. The network entity may further configure whether the network entity should transmit the multi-resource RSs with antenna switching first or repetition first. In one example, the network entity transmits the multi-resource RSs with antenna switching first. In another example, the network entity transmits the multi-resource RSs with repetition first.
Referring to FIG. 23, the network entity transmits the multi-resource RSs (resources 2301, 2302, 2303, 2304) with antenna switching first. The network entity 104 transmits an RS on resource 2301 from antennas or antenna ports 1 and 2, an RS on resource 2302 from antennas or antenna ports 3 and 4, an RS on resource 2303 from antennas or antenna ports 5 and 6 in resource 2101, and an RS on resource 2304 from antennas or antenna ports 7 and 8. The network entity may multiplex the RSs from different ports within the same resource in FDM manner, or CDM manner.
Referring to FIG. 24, the network entity transmits the multi-resource RSs (resources 2301, 2302, 2303, 2304) with repetition first. For example, the network entity 104 transmits the RS on resource 2301 from antennas or antenna ports 1 and 2 with repetition before transmitting the RS on resource 2302 from antennas or antenna ports 3 and 4.
In some examples, the UE reports the UE capability or assistance information indicating the supported or preferred antenna switching scheme across resources, e.g., full antenna switching or partial antenna switching. Then based on the UE report, the network entity may configure the network entity to transmit the multi-resource RS based on the full antenna port switching or partial antenna port switching.
In some examples, the network entity configures the antenna or antenna port index (es) for each resource, and the UE can reconstruct the channel based on the configured antenna or antenna port index (es) for each resource. Alternatively, the antenna or antenna port index (es) for each resource is predefined. In one example, the network entity may configureport (s) per resource, then the port (s) in resource k within the resource set should be from antenna or antenna port With the configured or predefined antenna or antenna port index (es) , the UE can measure and report the beamforming weight as discussed above in connection with FIGs. 14-16.
In some implementations, the UE reports an indicator indicating the beamforming weight report based on the number of ports across the set of multi-resource RS. In some implementations, the beamforming weight is a matrix with the dimension of N_Tx by 1 or 2, where N_Tx indicates the number of ports across the set of multi-resource RS. In some other implementations, the beamforming weight is a matrix with the dimension of N_Tx by N_Tx, _g, where N_Tx, _g is the maximum or minimum number of ports per resource. In some other implementations, the beamforming weight is a matrix with the dimension of N_Tx by L, where L is configured by the first control signaling by the network entity.
In some other implementations, the beamforming weight could have more ports, i.e., more rows, than the number of ports across the set of multi-resource RS. The network entity only transmits the multi-resource RS from a subset of antennas or antenna ports. The UE can predict the channel from all the antennas or all antenna ports with spatial domain interpolation or spatial domain prediction, e.g., spatial domain prediction with machine learning. Then the network entity may configure the number of horizontal antenna ports and number of vertical antenna ports for the beamforming weight report by the first control signaling. The network entity may further configure the location of each antenna port for each resource in the full antenna port structure by the first and/or second control signaling. The UE may report the UE capability indicating at least one of: the minimum number of measured antenna ports across the resources; the minimum number of measured horizontal antenna ports across the resources; the minimum number of measured vertical antenna ports across the resources; the preferred measured antenna port indexes in horizontal; the preferred measured antenna port indexes in vertical.
FIGs. 2-24 illustrate examples of beamforming weight measurement and report. FIGs. 25-26 show methods for implementing one or more aspects of FIGs. 2-24. In particular, FIG. 25 shows an implementation by the UE 102 of the one or more aspects of FIGs. 2-24. FIG. 26 shows an implementation by the network entity 104 of the one or more aspects of FIGs. 2-24.
FIG. 25 is a flowchart 2500 of a method of wireless communication at a UE for beamforming weight measurement and report. With reference to FIGs. 1 and 24, the method may be performed by the UE 102, the UE apparatus 2702, etc., which may include the memory 2726', 2706', 2716, and which may correspond to the entire UE 102 or the entire UE apparatus 2702, or a component of the UE 102 or the UE apparatus 2702, such as the wireless baseband processor 2726 and/or the application processor 2706.
The UE 102 may transmit 2503, to a NE, a UE capability report. For example, referring to FIG. 3, the UE 102 may send 303 a UE capability report indicating the UE capability indicating whether it supports the multi-port RS based beamforming weight measurement and report. For example, referring to FIG. 18, the UE 102 may send 1803 the UE capability indicating whether it supports the multi-resource RSs based beamforming weight measurement and report.
The UE 102 may receive 2504, from the NE, a control signal configuring the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule. For example, referring to FIG. 4, the UE 102 may receive 404 a control signal configuring the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule. For example, referring to FIG. 19, the UE 102 may receive 1904 a control signal configuring the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule.
The UE 102 may receive 2506, from the NE, a triggering signal triggering at least one of the beamforming weight report or the one or more downlink RSs. For example, referring to FIG. 4, the UE may receive 406 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the configured multi-port RS for beamforming weight measurement and report. For example, referring to FIG. 19, the UE may receive 1906 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the at least one set of RS resources for beamforming weight measurement and report.
The UE 102 receives 2508 the one or more downlink reference signals. For example, referring to FIG. 4, the UE receives 408 the at least one multi-port RS for beamforming weight measurement and report. For example, referring to FIG. 19, the UE receives 1908 the at least one set of RS resources for beamforming weight measurement and report.
The UE 102 quantizes 2510 beamforming weights based on measured quality of one or more downlink reference signals, RSs, emitted by the NE, using a plurality of antenna ports. For example, referring to FIG. 3, UE 102 quantizes 310 the beamforming weights based on measured quality of the at least one multi-port RS. For example, referring to FIG. 18, the UE 102 quantizes 1810 the beamforming weight based on measured quality of the at least one set of RSs.
The UE 102 sends 2512, to the NE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports. For example, referring to FIG. 3, the UE 102 sends 312 the beamforming weight report to the network entity. For example, referring to FIG. 18, the UE 102 sends 1812 the beamforming weight report to the network entity.
FIG. 26 is a flowchart 2600 of a method of wireless communication at a network entity for beamforming weight measurement and report. With reference to FIGs. 1-24, the method may be performed by one or more network entities 104, which may correspond to a base station or a unit of the base station, such as the RU 106, the DU 108, the CU 110, an RU processor 2806, a DU processor 2826, a CU processor 2846, etc. The one or more network entities 104 may include memory 2806’ /2826’ /2846’ , which may correspond to an entirety of the one or more network entities 104, or a component of the one or more network entities 104, such as the RU processor 2806, the DU processor 2826, or the CU processor 2846.
The network entity 104 may receive 2603, from a UE, a UE capability report. For example, referring to FIG. 5, the network entity 104 may receive 503 UE capability on multi-port RS based beamforming weight measurement and report. For example, referring to FIG. 20, the network entity 104 may receive 2003 UE capability on the multi-resource RSs based beamforming weight measurement and report.
The network entity 104 may configure 2604 the beamforming weight report to include the at least one set of beamforming weights based on a predetermined rule. For example, referring to FIG. 5, The network entity 104 may configure 504 the beamforming weight report to include the at least one set of beamforming weights selected based on a predetermined rule. For example, referring to FIG. 20, The network entity 104 may configure 2004 the beamforming weight report to include the at least one set of beamforming weights selected based on a predetermined rule.
The network entity 104 may transmit 2606, to the UE, a triggering signal triggering at least one of the beamforming weight report or the one or more downlink RSs. For example, referring to FIG. 5, the network entity 104 may transmit 506 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the configured multi-port RS for beamforming weight measurement and report. For example, referring to FIG. 20, the network entity 104 may transmit 2006 a second control signaling, e.g., MAC CE or DCI, triggering the configured beamforming weight report and/or the at least one set of RS resources for beamforming weight measurement and report.
The network entity 104 transmits 2608 the one or more downlink reference signals. For example, referring to FIG. 5, the network entity 104 transmits 508 the at least one multi-port RS for beamforming weight measurement and report. For example, referring to FIG. 20, the network entity 104 transmits 2008 the at least one set of RSs on the at least one set of RS resources for beamforming weight measurement and report.
The network entity receives 2612, from the UE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports. For example, referring to FIG. 5, the network entity 104 receives 512 the beamforming weight report from the UE. For example, referring to FIG. 20, the network entity 104 receives 2012 the beamforming weight report from the UE. A UE apparatus 2702, as described in FIG. 27, may perform the method of flowchart 2500. The one or more network entities 104, as described in FIG. 28, may perform the method of flowchart 2600.
FIG. 27 is a diagram 2700 illustrating an example of a hardware implementation for a UE apparatus 2702. The UE apparatus 2702 may be the UE 102, a component of the UE 102, or may implement UE functionality. The UE apparatus 2702 may include an application processor 2706, which may have on-chip memory 2706’ . In examples, the application processor 2706 may be coupled to a secure digital (SD) card 2708 and/or a display 2710. The application processor 2706 may also be coupled to a sensor (s) module 2712, a power supply 2714, an additional module of memory 2716, a camera 2718, and/or other related components. For example, the sensor (s) module 2712 may control a barometric pressure sensor/altimeter, a motion sensor such as an inertial management unit (IMU) , a gyroscope, accelerometer (s) , a light detection and ranging (LIDAR) device, a radio-assisted detection and ranging (RADAR) device, a sound navigation and ranging (SONAR) device, a magnetometer, an audio device, and/or other technologies used for positioning.
The UE apparatus 2702 may further include a wireless baseband processor 2726, which may be referred to as a modem. The wireless baseband processor 2726 may have on-chip memory 2726'. Along with, and similar to, the application processor 2706, the wireless baseband processor 2726 may also be coupled to the sensor (s) module 2712, the power supply 2714, the additional module of memory 2716, the camera 2718, and/or other related components. The wireless baseband processor 2726 may be additionally coupled to one or more subscriber identity module (SIM) card (s) 2720 and/or one or more transceivers 2730 (e.g., wireless RF transceivers) .
Within the one or more transceivers 2730, the UE apparatus 2702 may include a Bluetooth module 2732, a WLAN module 2734, an SPS module 2736 (e.g., GNSS module) , and/or a cellular module 2738. The Bluetooth module 2732, the WLAN module 2734, the SPS module 2736, and the cellular module 2738 may each include an on-chip transceiver (TRX) , or in some cases, just a transmitter (TX) or just a receiver (RX) . The Bluetooth module 2732, the WLAN module 2734, the SPS module 2736, and the cellular module 2738 may each include dedicated antennas and/or utilize antennas 2740 for communication with one or more other nodes. For example, the UE apparatus 2702 can communicate through the transceiver (s) 2730 via the antennas 2740 with another UE 102 (e.g., sidelink communication) and/or with a network entity 104 (e.g., uplink/downlink communication) , where the network entity 104 may correspond to a base station or a unit of the base station, such as the RU 106, the DU 108, or the CU 110.
The wireless baseband processor 2726 and the application processor 2706 may each include a computer-readable medium /memory 2726', 2706', respectively. The additional module of memory 2716 may also be considered a computer-readable medium /memory. Each computer-readable medium /memory 2726', 2706', 2716 may be non-transitory. The wireless baseband processor 2726 and the application processor 2706 may each be responsible for general processing, including execution of software stored on the computer-readable medium /memory 2726', 2706', 2716. The software, when executed by the wireless baseband processor 2726 /application processor 2706, causes the wireless baseband processor 2726 /application processor 2706 to perform the various functions described herein. The computer-readable medium /memory may also be used for storing data that is manipulated by the wireless baseband processor 2726 /application processor 2706 when executing the software. The wireless baseband processor 2726 /application processor 2706 may be a component of the UE 102. The UE apparatus 2702 may be a processor chip (e.g., modem and/or application) and include just the wireless baseband processor 2726 and/or the application processor 2706. In other examples, the UE apparatus 2702 may be the entire UE 102 and include the additional modules of the apparatus 2702.
As discussed, the beamforming weight component 140 is configured to quantize beamforming weights based on measured quality of one or more downlink reference signals, RSs, emitted by a network entity, NE, using a plurality of antenna ports. The beamforming weight component 140 is further configured to send, to the NE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports. The beamforming weight component 140 may be within the application processor 2706 (e.g., at 140a) , the wireless baseband processor 2726 (e.g., at 140b) , or both the application processor 2706 and the wireless baseband processor 2726. The beamforming weight component 140a-140b may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by the one or more processors, or a combination thereof.
FIG. 28 is a diagram 2800 illustrating an example of a hardware implementation for one or more network entities 104. The one or more network entities 104 may be a base station, a component of a base station, or may implement base station functionality. The one or more network entities 104 may include, or may correspond to, at least one of the RU 106, the DU, 108, or the CU 110. The CU 110 may include a CU processor 2846, which may have on-chip memory 2846'. In some aspects, the CU 110 may further include an additional module of memory 2856 and/or a communications interface 2848, both of which may be coupled to the CU processor 2846. The CU 110 can communicate with the DU 108 through a midhaul link 162, such as an F1 interface between the communications interface 2848 of the CU 110 and a communications interface 2828 of the DU 108.
The DU 108 may include a DU processor 2826, which may have on-chip memory 2826'. In some aspects, the DU 108 may further include an additional module of memory 2836 and/or the communications interface 2828, both of which may be coupled to the DU processor 2826. The DU 108 can communicate with the RU 106 through a fronthaul link 160 between the communications interface 2828 of the DU 108 and a communications interface 2808 of the RU 106.
The RU 106 may include an RU processor 2806, which may have on-chip memory 2806'. In some aspects, the RU 106 may further include an additional module of memory 2816, the communications interface 2808, and one or more transceivers 2830, all of which may be coupled to the RU processor 2806. The RU 106 may further include antennas 2840, which may be coupled to the one or more transceivers 2830, such that the RU 106 can communicate through the one or more transceivers 2830 via the antennas 2840 with the UE 102.
The on-chip memory 2806', 2826', 2846'a nd the additional modules of memory 2816, 2836, 2856 may each be considered a computer-readable medium /memory. Each computer-readable medium /memory may be non-transitory. Each of the processors 2806, 2826, 2846 is responsible for general processing, including execution of software stored on the computer-readable medium /memory. The software, when executed by the corresponding processor (s) 2806, 2826, 2846 causes the processor (s) 2806, 2826, 2846 to perform the various functions described herein. The computer-readable medium /memory may also be used for storing data that is manipulated by the processor (s) 2806, 2826, 2846 when executing the software. In examples, the report configuration component 150 may sit at any of the one or more network entities 104, such as at the CU 110; both the CU 110 and the DU 108; each of the CU 110, the DU 108, and the RU 106; the DU 108; both the DU 108 and the RU 106; or the RU 106.
As discussed, the report configuration component 150 is configured to configure a beamforming weight report associated with one or more reference signals, RSs. The report configuration component 150 is further configured to receive, from a user equipment, the beamforming weight report including beamforming weights based on a measured quality of the one or more RSs. The report configuration component 150 may be within one or more processors of the one or more network entities 104, such as the RU processor 2806 (e.g., at 150a) , the DU processor 2826 (e.g., at 150b) , and/or the CU processor 2846 (e.g., at 150c) . The report configuration component 150a-150c may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors 2806, 2826, 2846 configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by the one or more processors 2806, 2826, 2846, or a combination thereof.
The specific order or hierarchy of blocks in the processes and flowcharts disclosed herein is an illustration of example approaches. Hence, the specific order or hierarchy of blocks in the processes and flowcharts may be rearranged. Some blocks may also be combined or deleted. Dashed lines may indicate optional elements of the diagrams. The accompanying method claims present elements of the various blocks in an example order, and are not limited to the specific order or hierarchy presented in the claims, processes, and flowcharts.
The detailed description set forth herein describes various configurations in connection with the drawings and does not represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough explanation of various concepts. However, these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
Aspects of wireless communication systems, such as telecommunication systems, are presented with reference to various apparatuses and methods. These apparatuses and methods are described in the following detailed description and are illustrated in the accompanying drawings by various blocks, components, circuits, processes, call flows, systems, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.
An element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs) , central processing units (CPUs) , application processors, digital signal processors (DSPs) , reduced instruction set computing (RISC) processors, systems-on-chip (SoC) , baseband processors, field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other similar hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software, which may be referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof.
If the functionality described herein is implemented in software, the functions may be stored on, or encoded as, one or more instructions or code on a computer-readable medium, such as a non-transitory computer-readable storage medium. Computer-readable media includes computer storage media and can include a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer. Storage media may be any available media that can be accessed by a computer.
Aspects, implementations, and/or use cases described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, the aspects, implementations, and/or use cases may come about via integrated chip implementations and other non-module-component based devices, such as end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, artificial intelligence (AI) -enabled devices, machine learning (ML) -enabled devices, etc. The aspects, implementations, and/or use cases may range from chip-level or modular components to non-modular or non-chip-level implementations, and further to aggregate, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more techniques described herein.
Devices incorporating the aspects and features described herein may also include additional components and features for the implementation and practice of the claimed and described aspects and features. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes, such as hardware components, antennas, RF-chains, power amplifiers, modulators, buffers, processor (s) , interleavers, adders/summers, etc. Techniques described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc., of varying configurations.
The description herein is provided to enable a person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not limited to the aspects described herein, but are to be interpreted in view of the full scope of the present disclosure consistent with the language of the claims.
Reference to an element in the singular does not mean “one and only one” unless specifically stated, but rather “one or more. ” Terms such as “if, ” “when, ” and “while” do not imply an immediate temporal relationship or reaction. That is, these phrases, e.g., “when, ” do not imply an immediate action in response to or during the occurrence of an action, but simply imply that if a condition is met then an action will occur, but without requiring a specific or immediate time constraint for the action to occur. The terms “may” , “might” , and “can” , as used in this disclosure, often carry certain connotations. For example, “may” refers to a permissible feature that may or may not occur, “might” refers to a feature that probably occurs, and “can” refers to a capability (e.g., capable of) . The phrase “For example” often carries a similar connotation to “may” and, therefore, “may” is sometimes excluded from sentences that include “for example” or other similar phrases.
Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C” or “one or more of A, B, or C”include any combination of A, B, and/or C, such as A and B, A and C, B and C, or A and B and C, and may include multiples of A, multiples of B, and/or multiples of C, or may include A only, B only, or C only. Sets should be interpreted as a set of elements where the elements number one or more.
Unless otherwise specifically indicated, ordinal terms such as “first” and “second” do not necessarily imply an order in time, sequence, numerical value, etc., but are used to distinguish between different instances of a term or phrase that follows each ordinal term. Reference numbers, as used in the specification and figures, are sometimes cross-referenced among drawings to denote same or similar features. A feature that is exactly the same in multiple drawings may be labeled with the same reference number in the multiple drawings. A feature that is similar among the multiple drawings, but not exactly the same, may be labeled with reference numbers that have different leading numbers, but have one or more of the same trailing numbers (e.g., 206, 306, 406, etc., may refer to similar features in the drawings) . Sometimes an “X” is used to universally denote multiple variations of a feature. For instance, “X06” can universally refer to all reference numbers that end in “06” (e.g., 206, 306, 406, etc. ) .
Structural and functional equivalents to elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are encompassed by the claims. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ” As used herein, the phrase “based on” shall not be construed as a reference to a closed set of information, one or more conditions, one or more factors, or the like. In other words, the phrase “based on A” , where “A” may be information, a condition, a factor, or the like, shall be construed as “based at least on A” unless specifically recited differently.
The following examples are illustrative only and may be combined with other examples or teachings described herein, without limitation.
Example 1 is a method of wireless communication at a UE, including: quantizing beamforming weights based on measured quality of one or more downlink reference signals, RSs, emitted by a network entity, NE, using a plurality of antenna ports; and sending, to the NE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports.
Example 2 may be combined with example 1 and includes receiving, from the NE, a control signal configuring the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule.
Example 3 may be combined with example 2 and includes that the predetermined rule is that the at least one set of beamforming weights includes an eigenvector of a matrix calculated based on the measured quality of one or more downlink RSs.
Example 4 may be combined with example 3 and further includes that the beamforming weight report includes all coefficients of the eigenvector.
Example 5 may be combined with example 3 and further includes that the beamforming weight report includes non-zero power (NZP) coefficients of the eigenvector.
Example 6 may be combined with example 3 and includes that the beamforming weight report includes strongest coefficients of the eigenvector.
Example 7 may be combined with example 2 and includes that the predetermined rule is that the UE selects the at least one set of beamforming weights from a beamforming weight codebook, and the beamforming weight codebook includes a plurality of sets of beamforming weights with a plurality of directions.
Example 8 may be combined with example 7 and includes receiving, from the NE, a control signal configuring the beamforming weight codebook.
Example 9 may be combined with any of examples 1-8 and further includes receiving, from the network entity, a triggering signal triggering at least one of the beamforming weight report or the one or more downlink RSs.
Example 10 may be combined with any of examples 1-9 and includes that transmitting, to the network entity, a UE capability report that indicates the UE is able to perform at least one of: measuring the quality of a multi-port RS for the quantizing of the beamforming weights, or measuring a plurality of RSs emitted on a plurality of RS resources using the plurality of antenna ports.
Example 11 may be combined with example 10 and includes that the UE capability report indicates the UE is able to measure the multi-port RS, and the UE capability report further indicates at least one of: a maximum number of multi-port RS resources per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination or across all bands; a maximum number of multi-port RS resources in a slot per BWP, per CC, per band, per band combination or across all bands, or a number of antenna ports for the multi-port RS.
Example 12 may be combined with any of examples 1-11 and further includes that the one or more downlink RSs include a multi-port RS, where the plurality of antenna ports includes a plurality of antenna port groups, and that receiving the multi-port RS from the plurality of antenna port groups in a plurality of symbols on an RS resource, and each portion of the multi-port RS from each antenna port group among the plurality of antenna port groups is in a symbol of the plurality of symbols.
Example 13 may be combined with example 12 and includes that different portions of the multi-port RS from different antenna ports within an antenna port group for each symbol are in different subcarriers in each symbol.
Example 14 may be combined with example 12 and includes that different portions of the multi-port RS from different antenna ports within an antenna port group for each symbol are generated using different orthogonal cover codes in each symbol.
Example 15 may be combined with any of examples 12-14 and includes that the receiving the multi-port RS includes: tracking phase of one or more portions of the multi-port RS from one or more antenna ports using a portion of the multi-port RS from an antenna port present in at least one subcarrier across the plurality of symbols.
Example 16 may be combined with example 10 and includes that the UE capability report indicates the UE is able to measure the plurality of RSs, and the UE capability report further indicates at least one of: a maximum number of configured sets of multi-resource RSs per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination or per UE, a maximum number of RS resources in a slot per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination or per UE, or a number of resources per resource set for the set of RS resources.
Example 17 may be combined with any of examples 1-10 and 16 and includes receiving the plurality of RSs on the plurality of RS resources from the plurality of antenna ports for the beamforming weight report.
Example 18 may be combined with example 17 and includes that different RSs of the plurality of RSs on different resources of the plurality of RS resources are transmitted by different antenna ports of the plurality of antenna ports.
Example 19 may be combined with example 17 and includes that receiving the plurality of RSs on the plurality of RS resources includes: tracking phase of the plurality of RSs on the plurality of RS resources by receiving the plurality of RSs on the plurality of RS resources from at least one antenna port of the plurality of antenna ports.
Example 20 is a method of wireless communication at a network entity, including: configuring a beamforming weight report associated with one or more reference signals, RSs, emitted by the network entity, NE, using a plurality of antenna ports; receiving, from a user equipment, UE, the beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports.
Example 21 may be combined with example 20 and includes that transmitting, to the UE, a control signal configuring a beamforming weight codebook, the beamforming weight report indicating a plurality of beamforming weight indexes.
Example 22 is an apparatus for wireless communication for implementing a method as in any of examples 1-21.
Example 23 is a non-transitory computer-readable medium storing computer executable code, the code when executed by at least one processor causes the at least one processor to implement a method as in any of examples 1-21.

Claims

A method of wireless communication performed by a user equipment, UE, the method comprising:

quantizing (310, 410) beamforming weights based on measured quality of one or more downlink reference signals, RSs, emitted by a network entity, NE, using a plurality of antenna ports; and

sending (312, 412) , to the NE, a beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports.
The method of claim 1, the method further comprising:

receiving, (404) from the NE, a control signal configuring the beamforming weight report to select the at least one set of beamforming weights based on a predetermined rule.
The method of claim 2, wherein the predetermined rule is that the at least one set of beamforming weights includes an eigenvector of a matrix calculated based on the measured quality of one or more downlink RSs.
The method of claim 3, wherein the beamforming weight report includes all coefficients of the eigenvector.
The method of claim 3, wherein the beamforming weight report includes non-zero power (NZP) coefficients of the eigenvector.
The method of claim 3, wherein the beamforming weight report includes strongest coefficients of the eigenvector.
The method of claim 2, wherein the predetermined rule is that the UE selects the at least one set of beamforming weights from a beamforming weight codebook, the beamforming weight codebook including a plurality of sets of beamforming weights with a plurality of directions.
The method of claim 7, further comprising:

receiving, from the NE, a control signal configuring the beamforming weight codebook.
The method of any of claims 1-8, further comprising:

receiving (406) , from the network entity, a triggering signal triggering at least one of the beamforming weight report or the one or more downlink RSs.
The method of any of claims 1-9, further comprising:

transmitting, to the network entity, a UE capability report that indicates the UE is able to perform at least one of:

measuring the quality of a multi-port RS for the quantizing of the beamforming weights, or

measuring a plurality of RSs emitted on a plurality of RS resources using the plurality of antenna ports.
The method of claim 10, wherein the UE capability report indicates the UE is able to measure the multi-port RS, and the UE capability report further indicates at least one of:

a maximum number of multi-port RS resources per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination or across all bands;

a maximum number of multi-port RS resources in a slot per BWP, per CC, per band, per band combination or across all bands, or

a number of antenna ports for the multi-port RS.
The method of any of claims 1-11, wherein the one or more downlink RSs include a multi-port RS, wherein the plurality of antenna ports includes a plurality of antenna port groups, the method further comprising:

receiving the multi-port RS from the plurality of antenna port groups in a plurality of symbols on an RS resource, each portion of the multi-port RS from each antenna port group among the plurality of antenna port groups being in a symbol of the plurality of symbols.
The method of claim 12, wherein different portions of the multi-port RS from different antenna ports within an antenna port group for each symbol are in different subcarriers in each symbol.
The method of claim 12, wherein different portions of the multi-port RS from different antenna ports within an antenna port group for each symbol are generated using different orthogonal cover codes in each symbol.
The method of any of claims 12-14, wherein the receiving the multi-port RS comprises:

tracking phase of one or more portions of the multi-port RS from one or more antenna ports using a portion of the multi-port RS from an antenna port present in at least one subcarrier across the plurality of symbols.
The method of claim 10, wherein the UE capability report indicates the UE is able to measure the plurality of RSs, and the UE capability report further indicates at least one of:

a maximum number of configured sets of multi-resource RSs per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination or per UE,

a maximum number of RS resources in a slot per bandwidth part (BWP) , per component carrier (CC) , per band, per band combination or per UE, or

a number of resources per resource set for the set of RS resources.
The method of any of claims 1-10 and 16, wherein the one or more downlink RSs include a plurality of RSs on a plurality of RS resources, the method further comprising:

receiving the plurality of RSs on the plurality of RS resources from the plurality of antenna ports for the beamforming weight report.
The method of claim 17, wherein different RSs of the plurality of RSs on different resources of the plurality of RS resources are transmitted by different antenna ports of the plurality of antenna ports.
The method of claim 17, wherein receiving the plurality of RSs on the plurality of RS resources comprises:

tracking phase of the plurality of RSs on the plurality of RS resources by receiving the plurality of RSs on the plurality of RS resources from at least one antenna port of the plurality of antenna ports.
A method of wireless communication at a network entity, comprising:

configuring a beamforming weight report associated with one or more reference signals, RSs, emitted by the network entity, NE, using a plurality of antenna ports;

receiving, from a user equipment, UE, the beamforming weight report including at least one set of the beamforming weights for the plurality of antenna ports.
The method of claim 20, further comprising:

transmitting, to the UE, a control signal configuring a beamforming weight codebook, the beamforming weight report indicating a plurality of beamforming weight indexes.
An apparatus for wireless communication comprising a transceiver, a memory, and a processor coupled to the memory and the transceiver, the apparatus being configured to perform a method as in any of claims 1-21.