Method and apparatus for wireless communication using super large antenna array

Abstract

Various aspects of the present disclosure relate to methods and apparatus for wireless communications utilizing a super large antenna array. Some embodiments of the methods and apparatus described herein can include a user equipment (UE) for wireless communication comprising at least one memory; and at least one processor coupled with the at least one memory and configured to cause the UE to receive, from a base station (BS), downlink (DL) reference signals (RSs) on a plurality of DL RS resource sets, wherein each DL RS resource set is associated with a respective subarray of an antenna array, and for each DL RS resource set, DL RSs on different DL RS resources of the DL RS resource set are associated with different beamforming vectors applied to the respective subarray associated with the DL RS resource set, and transmit, to the BS, a channel state information (CSI) report indicating, for each DL RS resource set of the plurality of DL RS resource sets, an index of a strongest DL RS resource of the DL RS resource set and a corresponding phase, wherein the DL RS of the strongest DL RS resource has a highest received strength among DL RSs on all DL RS resources of the DL RS resource set, and the corresponding phase corresponds to a received phase of the DL RS on the strongest DL RS resource.

Description

Technical Field

[0001] This disclosure relates to wireless communication, and more specifically, to methods and apparatus for wireless communication utilizing very large antenna arrays. Background Technology

[0002] A wireless communication system may include one or more network communication devices, such as base stations, that support wireless communication for one or more user communication devices, which may also be referred to as user equipment (UE) or other suitable terms. The wireless communication system can support wireless communication with one or more user communication devices by utilizing the resources of the wireless communication system (e.g., time resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency resources (e.g., subcarriers, carriers, etc.)). Furthermore, the wireless communication system can support wireless communication across a variety of radio access technologies, including third-generation (3G), fourth-generation (4G), fifth-generation (5G), and other suitable radio access technologies other than 5G (e.g., sixth-generation (6G)). Summary of the Invention

[0003] The article “a” preceding an element is not limited and should be understood to refer to “at least one” or “one or more” of those elements. The terms “a,” “at least one,” “one or more,” and “at least one of one or more” are interchangeable. As used herein, the word “or” included in the claims, as used in a list of items (e.g., a list of items beginning with phrases such as “at least one,” “one or more,” or “one or two”), indicates an inclusive list such that a list of at least one of, for example, A, B, or C, means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Furthermore, as used herein, the phrase “based on” should not be construed as referring to a closed set of conditions. For example, without departing from the scope of this disclosure, an example step described as “based on condition A” may be based on both condition A and condition B. In other words, as used herein, the phrase “based on” should be interpreted in the same manner as the phrase “at least partially based on.” Furthermore, as used herein, included in the claims, “group” may comprise one or more elements.

[0004] Some embodiments of the methods and apparatus described herein may include a UE for wireless communication, comprising: at least one memory; and at least one processor coupled to the at least one memory and configured such that the UE: receives DL RS from a base station (BS) on a plurality of downlink (DL) reference signal (RS) resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, DL RS on different DL RS resources in the DL RS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DL RS resource set; and transmits to the BS a Channel State Information (CSI) report indicating, for each DL RS resource set in the plurality of DL RS resource sets, the index of the strongest DL RS resource in the DL RS resource set and the corresponding phase, wherein the DL RS of the strongest DL RS resource has the highest received strength among all DL RS on all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the received phase of the DL RS on the strongest DL RS resource.

[0005] In some embodiments of the UE described herein, the at least one processor is further configured to cause the UE to: perform measurements of DL RS on all DL RS resources in the plurality of DL RS resource sets to determine the strongest DL RS resource and the corresponding phase in each DL RS resource set.

[0006] In some implementations of the UE described herein, different DL RS resources in the same DL RS resource set do not overlap in the time domain, and different DL RS resources in different DL RS resource sets are associated with the same time domain resource or different time domain resources.

[0007] In some implementations of the UE described herein, each DL RS resource in the plurality of DL RS resource sets is a single-port DL RS resource.

[0008] In some implementations of the UE described herein, the at least one processor is further configured to cause the UE to: receive configuration information from the BS indicating the plurality of DL RS resource sets.

[0009] In some embodiments of the UE described herein, the at least one processor is further configured to cause the UE to: receive from the BS a CSI report configuration associated with the plurality of DL RS resource sets, wherein the CSI report configuration indicates, based on measurements of DL RS on the plurality of DL RS resource sets, that a CSI report for each DL RS resource set indicates the index and the corresponding phase of the strongest DL RS resource in the DL RS resource set.

[0010] In some implementations of the UE described herein, each corresponding phase indicated by the CSI report is a phase offset relative to one of the received phases of the DL RS on the strongest DL RS resource indicated by the CSI report.

[0011] In some implementations of the UE described herein, one is the maximum received phase among all DL RSs on the strongest DL RS resource indicated by the CSI report.

[0012] In some implementations of the UE described herein, the corresponding phase indicated by the CSI report is quantized.

[0013] In some embodiments of the UE described herein, the at least one processor is further configured to cause the UE to: receive from the BS a DL transmission using a subarray-based maximum ratio combining (MRC) scheme based on the CSI report, wherein for each subarray used for the DL transmission, a beamforming vector associated with the strongest DL RS resource in the DL RS resource set associated with the subarray indicated by the CSI report, and the corresponding phase of the DL RS resource set associated with the subarray indicated by the CSI report, are applied.

[0014] In some implementations of the UE described herein, the DL transmission is the transmission of CSI-RS on a single CSI-RS resource using all subarrays of the antenna array.

[0015] In some implementations of the UE described herein, the CSI-RS is a tracking RS (TRS) for the UE to perform time and frequency tracking of the antenna array.

[0016] Some embodiments of the methods and apparatus described herein may include a BS for wireless communication, comprising: at least one memory; and at least one processor coupled to the at least one memory and configured such that the BS: transmits DL RS to a UE on a plurality of DL RS resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, the corresponding subarray associated with the DL RS resource set transmits DL RS on different DL RS resources in the DL RS resource set using different beamforming vectors; and receives from the UE a CSI report indicating, for each DL RS resource set in the plurality of DL RS resource sets, an index and corresponding phase of the strongest DL RS resource in the DL RS resource set, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS on all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource.

[0017] In some implementations of the BS described herein, a common phase offset is used to transmit the DL RS on all DL RS sources in the plurality of DL RS resource sets.

[0018] In some implementations of the BS described herein, the common phase offset is zero.

[0019] In some implementations of the BS described herein, different DL RS resources in the same DL RS resource set do not overlap in the time domain, and different DL RS resources in different DL RS resource sets are associated with the same time domain resource or different time domain resources.

[0020] In some implementations of the BS described herein, each DL RS resource in the plurality of DL RS resource sets is a single-port DL RS resource.

[0021] In some implementations of the BS described herein, the at least one processor is further configured to cause the BS to transmit configuration information to the UE indicating the plurality of DL RS resource sets.

[0022] In some implementations of the BS described herein, the at least one processor is further configured to cause the BS to: transmit to the UE a CSI report configuration associated with the plurality of DL RS resource sets, wherein the CSI report configuration indicates, based on measurements of DL RS on the plurality of DL RS resource sets, that a CSI report for each DL RS resource set indicates the index and the corresponding phase of the strongest DL RS resource in the DL RS resource set.

[0023] In some implementations of the BS described herein, each corresponding phase indicated by the CSI report is a phase offset relative to one of the received phases of the DL RS on the strongest DL RS resource indicated by the CSI report.

[0024] In some implementations of the BS described herein, one is the maximum received phase among all the DL RSs on the strongest DL RS resource, as indicated by the CSI report.

[0025] In some implementations of the BS described herein, the corresponding phase indicated by the CSI report is quantized.

[0026] In some implementations of the BS described herein, the at least one processor is further configured to cause the BS to: transmit DL transmissions to the UE using a subarray-based MRC scheme based on the CSI report, wherein for each subarray used for the DL transmission, a beamforming vector associated with the strongest DL RS resource in the DL RS resource set associated with the subarray indicated by the CSI report, and the corresponding phase of the DL RS resource set associated with the subarray indicated by the CSI report, are applied.

[0027] In some implementations of the BS described herein, the DL transmission is the transmission of CSI-RS on a single CSI-RS resource using all subarrays of the antenna array.

[0028] In some implementations of the BS described herein, the CSI-RS is a TRS for the UE to perform time and frequency tracking of the antenna array.

[0029] Some embodiments of the methods and apparatus described herein may include a processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured such that the processor: receives DL RS from a BS on a plurality of DL RS resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, DL RS on different DL RS resources in the DL RS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DL RS resource set; and transmits to the BS a CSI report indicating, for each DL RS resource set in the plurality of DL RS resource sets, an index and corresponding phase of the strongest DL RS resource in the DL RS resource set, wherein the DL RS of the strongest DL RS resource has the highest received strength among all DL RS on all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the received phase of the DL RS on the strongest DL RS resource.

[0030] Some embodiments of the methods and apparatus described herein may include a processor for wireless communication, comprising: at least one controller coupled to at least one memory and configured such that the processor: transmits DL RS to a UE on a plurality of DL RS resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, the corresponding subarray associated with the DL RS resource set transmits DL RS on different DL RS resources in the DL RS resource set using different beamforming vectors; and receives from the UE a CSI report indicating, for each DL RS resource set in the plurality of DL RS resource sets, an index and corresponding phase of the strongest DL RS resource in the DL RS resource set, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS on all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource.

[0031] Some embodiments of the methods and apparatus described herein may include a method performed by a UE, the method comprising: receiving DL RS from a BS on a plurality of DL RS resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, DL RS on different DL RS resources in the DL RS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DL RS resource set; and transmitting to the BS a CSI report indicating, for each DL RS resource set in the plurality of DL RS resource sets, the index and corresponding phase of the strongest DL RS resource in the DL RS resource set, wherein the DL RS of the strongest DL RS resource has the highest received strength among all DL RS on all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the received phase of the DL RS on the strongest DL RS resource.

[0032] Some embodiments of the methods and apparatus described herein may include a method performed by a BS, the method comprising: transmitting DL RS to a UE on a plurality of DL RS resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, the corresponding subarray associated with the DL RS resource set transmits DL RS on different DL RS resources in the DL RS resource set using different beamforming vectors; and receiving from the UE a CSI report indicating, for each DL RS resource set in the plurality of DL RS resource sets, an index and corresponding phase of the strongest DL RS resource in the DL RS resource set, wherein the DL RS of the strongest DL RS resource has the highest received strength among all DL RS on all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the received phase of the DL RS on the strongest DL RS resource. Attached Figure Description

[0033] Figure 1 Examples of wireless communication systems according to aspects of this disclosure are described.

[0034] Figure 2 Examples of hybrid beamforming architectures according to aspects of this disclosure are illustrated.

[0035] Figures 3A to 3D Exemplary beam patterns of three different beamforming schemes for a UE at different distances from the antenna array, according to aspects of this disclosure.

[0036] Figure 4This describes the received phase of the corresponding strongest DL RS from multiple subarrays of an antenna array according to aspects of this disclosure.

[0037] Figure 5 This describes the transmit phase of the antenna elements in the antenna array according to aspects of this disclosure.

[0038] Figure 6 This describes a comparison between the beam pattern of DL transmission using a subarray-based MRC scheme and an ideal beamforming pattern, according to aspects of this disclosure.

[0039] Figure 7 Examples of UEs based on aspects of this disclosure are described.

[0040] Figure 8 Examples of processors according to aspects of this disclosure are described.

[0041] Figure 9 Examples of network equipment (NE) according to aspects of this disclosure are described.

[0042] Figure 10 A flowchart illustrating an exemplary method performed by a UE according to aspects of this disclosure.

[0043] Figure 11 A flowchart illustrating an exemplary method performed by an NE according to aspects of this disclosure. Detailed Implementation

[0044] To facilitate understanding, embodiments of this disclosure are provided under specific network architectures and service scenarios (such as 3GPP Long Term Evolution (LTE) and LTE Advanced, 3GPP 5G New Radio (NR), 5G Advanced, 6G, etc.). It has been considered that all embodiments in this disclosure are applicable to similar technical problems as network architectures and new service scenarios evolve; furthermore, the terminology cited in this disclosure may be changed without affecting the principles of this disclosure.

[0045] Aspects of this disclosure are described in the context of wireless communication systems.

[0046] Figure 1This section describes an example of a wireless communication system 100 according to aspects of this disclosure. The wireless communication system 100 may include one or more NEs 102, one or more UEs 104, and a core network (CN) 106. The wireless communication system 100 may support various radio access technologies. In some embodiments, the wireless communication system 100 may be a 4G network, such as an LTE network or an LTE-A network. In some other embodiments, the wireless communication system 100 may be an NR network, such as a 5G network, a 5G-A network, or a 5G Ultra Wideband (5G-UWB) network. In other embodiments, the wireless communication system 100 may be a combination of 4G and 5G networks, or other suitable radio access technologies, including IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), and IEEE 802.20. The wireless communication system 100 may support radio access technologies other than 5G, such as 6G. In addition, the wireless communication system 100 can support technologies such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), or Code Division Multiple Access (CDMA).

[0047] One or more NEs 102 may be distributed across a geographical area to form a wireless communication system 100. One or more of the NEs 102 described herein may be, include, or be referred to as a network node, base station, network element, network function, network entity, radio access network (RAN), NodeB, eNodeB (eNB), next-generation NodeB (gNB), or other suitable terms. NEs 102 and UEs 104 may communicate via a communication link, which may be a wireless or wired connection. For example, NEs 102 and UEs 104 may perform wireless communication (e.g., receive signaling, transmit signaling) via a Uu interface.

[0048] NE 102 can provide a geographic coverage area within which it can support services for one or more UEs 104. For example, NE 102 and UE 104 can support wireless communication of signals associated with services (e.g., voice, video, packet data, messaging, broadcasting, etc.) based on one or more radio access technologies. In some embodiments, NE 102 can be mobile, for example, a satellite associated with a non-terrestrial network (NTN). In some embodiments, different geographic coverage areas associated with the same or different radio access technologies may overlap, but different geographic coverage areas may be associated with different NEs 102.

[0049] One or more UEs 104 may be distributed across a geographical area of ​​the wireless communication system 100. UE 104 may include or be referred to as a remote unit, mobile device, wireless device, remote device, subscriber device, transmitter device, receiver device, or some other suitable term. In some implementations, UE 104 may be referred to as a unit, station, terminal, or client, and other instances thereof. Additionally or alternatively, UE 104 may be referred to as an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a Machine Type Communication (MTC) device, and other instances thereof.

[0050] UE 104 may be able to support direct wireless communication with other UE 104 via a communication link. For example, UE 104 may support direct wireless communication with another UE 104 via a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, the communication link may be referred to as a sidelink. For example, UE 104 may support direct wireless communication with another UE 104 via a PC5 interface.

[0051] NE 102 may support communication with CN 106 or with another NE 102, or both. For example, NE 102 may interface with other NE 102 or CN 106 via one or more backhaul links (e.g., S1, N2, N2, or network interfaces). In some embodiments, NE 102 may communicate directly with each other. In some other embodiments, NE 102 may communicate indirectly with each other (e.g., via CN 106). In some embodiments, one or more NE 102 may include sub-components, such as access network entities, which may be instances of Access Node Controllers (ANCs). The ANC may communicate with one or more UEs 104 via one or more other access network transmitting entities (which may be referred to as radio heads, smart radio heads, or transmit-receive points (TRPs)).

[0052] CN 106 can support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. CN 106 can be an evolved packet core (EPC) or a 5G core (5GC), which may include control plane entities (e.g., Mobility Management Entity (MME), Access and Mobility Management Function (AMF)) that manage access and mobility, and user plane entities (e.g., Serving Gateway (S-GW), Packet Data Network (PDN) Gateway (P-GW), or User Plane Function (UPF)) that route packets or interconnect to external networks. In some implementations, the control plane entities may manage non-access stratum (NAS) functions of one or more UEs 104 served by one or more NEs 102 associated with CN 106, such as mobility, authentication, and bearer management (e.g., data bearers, signaling bearers, etc.).

[0053] CN 106 can communicate with the packet data network via one or more backhaul links (e.g., via S1, N2, N2, or another network interface). The packet data network may contain an application server. In some implementations, one or more UEs 104 can communicate with the application server. UE 104 can establish a session (e.g., a Protocol Data Unit (PDU) session, etc.) with CN 106 via NE 102. CN 106 can use the established session (e.g., an established PDU session) to route services (e.g., control information, data, etc.) between UE 104 and the application server. A PDU session may be an instance of a logical connection between UE 104 and CN 106 (e.g., one or more network functions of CN 106).

[0054] In the wireless communication system 100, NE 102 and UE 104 can use the resources of the wireless communication system 100 (e.g., time resources (e.g., symbols, time slots, subframes, frames, etc.) or frequency resources (e.g., subcarriers, carriers)) to perform various operations (e.g., wireless communication). In some embodiments, NE 102 and UE 104 may support different resource structures. For example, NE 102 and UE 104 may support different frame structures. In some embodiments, such as in 4G, NE 102 and UE 104 may support a single frame structure. In some other embodiments, such as in 5G and other suitable radio access technologies, NE 102 and UE 104 may support various frame structures (i.e., multiple frame structures). NE 102 and UE 104 may support various frame structures based on one or more parameter sets.

[0055] The wireless communication system 100 may support one or more parameter sets, and the parameter sets may include subcarrier spacing and cyclic prefixes. A first parameter set (e.g., μ=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a regular cyclic prefix. In some embodiments, the first parameter set (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one time slot per subframe. A second parameter set (e.g., μ=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a regular cyclic prefix. A third parameter set (e.g., μ=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a regular cyclic prefix or an extended cyclic prefix. A fourth parameter set (e.g., μ=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a regular cyclic prefix. A fifth parameter set (e.g., μ=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a regular cyclic prefix.

[0056] Time intervals for resources (e.g., communication resources) can be organized according to frames (also known as radio frames). Each frame may have a duration, for example, 10 milliseconds (ms). In some embodiments, each frame may contain multiple subframes. For example, each frame may contain 10 subframes, and each subframe may have a duration, for example, 1 ms. In some embodiments, each frame may have the same duration. In some embodiments, each subframe of a frame may have the same duration.

[0057] Alternatively, the time intervals of resources (e.g., communication resources) can be organized according to time slots. For example, a subframe may contain a certain number (e.g., quantity) of time slots. The number of time slots in each subframe may also depend on one or more parameter sets supported in the wireless communication system 100. For example, the first, second, third, fourth, and fifth parameter sets (i.e., μ=0, μ=1, μ=2, μ=3, μ=4) associated with corresponding subcarrier intervals of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz may utilize one time slot per subframe, two time slots per subframe, four time slots per subframe, eight time slots per subframe, and 16 time slots per subframe, respectively. Each time slot may contain a certain number (e.g., quantity) of symbols (e.g., Orthogonal Frequency Division Multiplexing (OFDM) symbols). In some embodiments, the number (e.g., quantity) of time slots in a subframe may depend on the parameter set. For a conventional cyclic prefix, a time slot may contain 14 symbols. For an extended cyclic prefix (e.g., applicable to a 60 kHz subcarrier spacing), a time slot may contain 12 symbols. The relationship between the number of symbols per time slot for the regular cyclic prefix and the extended cyclic prefix, the number of time slots per subframe, and the number of time slots per frame may depend on the parameter set. It should be understood that references to the first parameter set (e.g., μ=0) associated with the first subcarrier spacing (e.g., 15 kHz) may be used interchangeably between subframes and time slots.

[0058] In the wireless communication system 100, the electromagnetic (EM) spectrum can be divided into various categories, frequency bands, channels, etc., based on frequency or wavelength. For example, the wireless communication system 100 may support one or more operating frequency bands, such as frequency range names FR1 (410 MHz to 7.125 GHz), FR2 (24.25 GHz to 52.6 GHz), FR3 (7.125 GHz to 24.25 GHz), FR4 (52.6 GHz to 114.25 GHz), FR4a or FR4-1 (52.6 GHz to 71 GHz), and FR5 (114.25 GHz to 300 GHz). In some embodiments, NE 102 and UE 104 may perform wireless communication on one or more of the operating frequency bands. In some embodiments, FR1 may be used by NE 102 and UE 104, as well as other equipment or devices, for cellular communication services (e.g., control information, data). In some implementations, FR2 can be used by NE 102 and UE 104, as well as other equipment or devices, for short-range, high data rate capabilities.

[0059] FR1 may be associated with one or more parameter sets (e.g., at least three parameter sets). For example, FR1 may be associated with a first parameter set containing a 15 kHz subcarrier spacing (e.g., μ=0); a second parameter set containing a 30 kHz subcarrier spacing (e.g., μ=1); and a third parameter set containing a 60 kHz subcarrier spacing (e.g., μ=2). FR2 may be associated with one or more parameter sets (e.g., at least two parameter sets). For example, FR2 may be associated with a third parameter set containing a 60 kHz subcarrier spacing (e.g., μ=2); and a fourth parameter set containing a 120 kHz subcarrier spacing (e.g., μ=3).

[0060] Multiple-input multiple-output (MIMO) has become a fundamental part of 4G or 5G systems and is likely to continue to be an important component of 6G networks. Massive MIMO (also known as massive MIMO or MIMO with massive antenna arrays) is a MIMO technique in which the NE (Network Element) can be equipped with a large number of antenna elements (e.g., 50 antenna elements) used to perform transmissions that share the same time and frequency band but are spatially separated. Massive MIMO is one of the most critical technologies in 5G communications. By using massive antenna arrays at the NE, massive MIMO can improve spectral efficiency by several orders of magnitude through beamforming or multiplexing. Here, the terms "antenna element" and "antenna" are used interchangeably.

[0061] For 6G communication, Ultra-Large-Scale MIMO (XL-MIMO), a type of MIMO where the antenna element (NE) can be equipped with a much larger number of antennas than in Massive MIMO, can effectively achieve a 10-fold increase in spectral efficiency. On the other hand, high-frequency communication can provide a large amount of available bandwidth thanks to the abundant spectrum resources in the millimeter-wave (mmWave) or terahertz (THz) bands. Simultaneously, the extremely small size of high-frequency antennas facilitates the deployment of XL-MIMO with a very large number of antennas. Therefore, high-frequency XL-MIMO may be a key enabling technology for 6G communication.

[0062] As the size of the antenna array increases, the electromagnetic (EM) field begins to exhibit some near-field properties. Specifically, the Rayleigh distance (e.g., denoted as ), which defines the boundary between the near and far fields, is... The calculation is as follows:

[0063]

[0064] Where D is the maximum size of the antenna array, and It is the wavelength.

[0065] The value of D increases with the size of the antenna array, and When the value of decreases with increasing frequency, the Rayleigh distance can increase, which means that the near-field zone increases, and therefore more UEs are included in the near-field zone.

[0066] The propagation of electromagnetic waves in the near field is explained as follows.

[0067] Typical antennas in very large antenna arrays can still be electric dipole antennas (unidirectional or cross-polarized). The electric field from the oscillating electric dipole ( )as follows:

[0068] ,

[0069] in

[0070] It is the electric dipole moment of the electric dipole at the origin;

[0071] Perpendicular to the direction vector ;

[0072] ;and

[0073] It is an outgoing spherical wave with velocity c.

[0074] Because a vacuum (or air) is a linear medium, the electric field of the near-field EM wave radiated from the antenna array is the sum of the electric fields radiated from all the antennas in the array. Therefore, the near-field signal received from the antenna array can be calculated as the sum of the signals from all the antennas in the array.

[0075] In the far field, EM waves radiated from an antenna array can be considered as a combination of plane waves. Therefore, the design of massive MIMO in 5G NR is based on the plane wave assumption. However, in the near field, EM waves radiated from an antenna array cannot be considered as a combination of plane waves. Therefore, the design of massive MIMO in 5G NR may not be suitable for XL-MIMO, and the use of XL-MIMO in 6G with near-field characteristics requires new designs for channel models, transceiver architectures, channel estimation, transmission schemes, etc.

[0076] Hybrid beamforming is widely used in mmWave systems to reduce hardware costs and simplify the system, and is supported in 5G NR systems. Instead of using a dedicated radio frequency (RF) chain (which may contain analog-to-digital converters (ADCs), digital-to-analog converters (DACs), power amplifiers (PAs), up-to-down converters, etc.) to drive each antenna port, the RF chain is used to drive a subset of antenna elements in the antenna array.

[0077] Figure 2 An example of a hybrid beamforming architecture according to aspects of this disclosure is described. This example includes both a transmitter side and a receiver side.

[0078] Hybrid beamforming architectures can incorporate beamforming in both the digital and analog domains. Specifically, digital weights are applied at each RF chain (e.g., via baseband digital precoding), and at the antenna element level, the signal is adjusted via analog phase shifters (e.g., via RF analog precoding), which only changes the signal's phase. Therefore, precoding is performed in two stages at the transmitter side. Correspondingly, the combining operation is also performed in two stages at the receiver side, for example, RF analog combining and baseband digital combining.

[0079] exist Figure 2 In this context, sharp beams formed using analog beamforming (e.g., via phase shifters) compensate for the large path loss in the mmWave band, while digital beamforming provides the necessary flexibility to perform advanced multi-antenna techniques such as multi-beam MIMO.

[0080] In conventional beamforming, it is assumed that the UE is in the far field, and therefore the same departure angle or the same arrival angle can be applied to the entire antenna array. Because in the far field, the EM wave can be considered as a plane wave (or a combination of plane waves), the beamforming vectors driving a subset or all of the antenna elements in the antenna array are discrete Fourier transform (DFT) vectors oriented towards the direction of the outgoing or incoming wave.

[0081] However, in the near field, EM waves are no longer plane waves (or combinations of plane waves), and the DFT vectors used under the plane wave assumption may no longer be applicable.

[0082] Ideal beamforming vectors need to be adapted to nonplanar EM wavefronts, which is very complex. Therefore, it is advantageous to find a low-complexity solution to simplify the design and reduce implementation costs.

[0083] To address this, this disclosure proposes a simplified design in which an antenna array with non-negligible near-field effects (e.g., a very large antenna array) can be divided into multiple subarrays. For each subarray, a corresponding beamforming vector can be applied to direct the corresponding beam toward the target UE in the corresponding direction. That is, different subarrays can use different beamforming vectors to direct their beams toward the same target UE in different directions. This disclosure proposes some solutions for determining different beamforming vectors for different subarrays, which may include estimating the near-field channel through UE and CSI feedback reports.

[0084] In this disclosure, the antenna array of the NE (e.g., BS) is divided into multiple subarrays (e.g., K subarrays), and each subarray may have a corresponding index and may contain several neighboring antenna elements. For example, in the case that the antenna array is one-dimensional, the k-th subarray, i.e., the subarray with index k (also called subarray k), may contain a total of 2M+1 antenna elements in one dimension. The distance between adjacent antenna elements in the subarray is d. The antenna element at the center of the subarray is called the 0th antenna element, the antenna elements next to the 0th array element are called the 1st antenna element and the (-1)th antenna element, ..., and the antenna elements on the edge of the subarray are called the Mth antenna element and the (-M)th antenna element. Conventional analog beamforming architectures (e.g., similar to...) Figure 2 The architecture described herein can be applied to each subarray. In some embodiments, DFT-based beamforming vectors can be applied to each subarray.

[0085] However, the BS may not know how to apply DFT-based beamforming vectors to the UE's transmission, or what DFT-based beamforming vectors to use in the transmission. The ideal method for transmitting from an antenna array to the UE is MRC, where the phases of all antennas in the antenna array are fine-tuned to be properly aligned at the UE for maximum signal strength. This may require the UE to estimate the phases of all antennas and provide appropriate feedback, which can be complex and impractical. According to some embodiments of this disclosure, a subarray-based MRC scheme (also known as a subarray-based DFT beamforming scheme) can be used to simplify system design.

[0086] For an antenna array divided into K subarrays, different beamforming vectors can be applied to different subarrays to implement a subarray-based MRC scheme. For example, beamforming vectors... This can be applied to subarray k, which can be a DFT-based beamforming vector, as follows:

[0087]

[0088] in:

[0089] It is the offset phase of subarray k relative to the reference subarray (e.g., the center subarray);

[0090] 2M+1 is the total number of antenna elements in subarray k;

[0091] It is the DFT phase gradient in subarray k; and

[0092] m is the index of the antenna element in subarray k, and .

[0093] The beam emitted from subarray k is directed towards the UE via 2M+1 antenna elements or reflected back to the UE via a reflector. Since only the relative phase is important, in a subarray-based MRC scheme, the phase offset of subarray k, i.e. It can be the relative phase (also known as phase offset) from the center antenna element of subarray k to the center antenna element of the entire antenna array.

[0094] Figures 3A to 3D Exemplary beam patterns of three different beamforming schemes for a UE at different distances from the antenna array, according to aspects of this disclosure. The three different beamforming schemes are an ideal MRC beamforming scheme (e.g., denoted as IdealBF), a whole-array DFT-based beamforming scheme (denoted as wholeArrayDFT, where DFT-based beamforming vectors are applied to the whole array), and a subarray-based DFT beamforming scheme (denoted as subarrayDFT).

[0095] exist Figures 3A to 3D In the example described, the BS's antenna array is divided into 5 subarrays. The beam pattern is represented by the normalized power (vertical coordinate, in dB) received by the UE at different positions (horizontal coordinate, represented by displacement relative to the center point, in "wavelength") in a plane parallel to the antenna array.

[0096] Figure 3AThe beam pattern of the UE at a distance of 0.05 Rayleigh from the antenna array is illustrated. As depicted, the beam pattern of the full-array DFT-based beamforming scheme has a wider beam and lower gain compared to the beam pattern of the ideal MRC beamforming scheme. Specifically, it can be seen that at the center point (i.e., horizontal coordinate 0), the normalized received power of the full-array DFT-based beamforming scheme is about 9 dB lower than that of the ideal MRC beamforming scheme, and the normalized received power of the sidebeams (e.g., approximately 50 wavelengths horizontally) of the full-array DFT-based beamforming scheme is much higher than that of the ideal MRC beamforming scheme. In contrast, the beam pattern of the subarray-based DFT beamforming scheme is similar to that of the ideal MRC beamforming scheme.

[0097] Figure 3B This describes the beam pattern of the UE at a distance of 0.1 Rayleigh from the antenna array. Compared to the beam pattern of an ideal MRC beamforming scheme, the beam pattern of the full-array DFT-based beamforming scheme still has a wider beam and lower gain. Specifically, it can be seen that at the center point (i.e., horizontal coordinate 0), the normalized received power of the full-array DFT-based beamforming scheme is about 5 dB lower than that of the ideal MRC beamforming scheme, and the normalized received power of the side beams (e.g., approximately 50 wavelengths horizontally) of the full-array DFT-based beamforming scheme is still higher than that of the ideal MRC beamforming scheme. In contrast, the beam pattern of the subarray-based DFT beamforming scheme is also similar to that of the ideal MRC beamforming scheme.

[0098] Figure 3C This illustrates the beam pattern of the UE at a distance of 0.25 Rayleigh from the antenna array. Compared to the beam pattern of an ideal MRC beamforming scheme, the beam pattern of the full-array DFT-based beamforming scheme still exhibits a wider beam and lower gain. Specifically, it can be seen that at the center point (i.e., horizontal coordinate 0), the normalized received power of the full-array DFT-based beamforming scheme is approximately 3 dB lower than that of the ideal MRC beamforming scheme, and the normalized received power of the side beams (e.g., approximately 50 wavelengths horizontally) of the full-array DFT-based beamforming scheme is still higher than that of the ideal MRC beamforming scheme. In contrast, the beam pattern of the subarray-based DFT beamforming scheme is also similar to that of the ideal MRC beamforming scheme.

[0099] Figure 3D The beam pattern of the UE at a distance of 0.5 Rayleigh is illustrated. Since the electric field at this distance may begin to exhibit some far-field properties, the beam patterns of the three beamforming schemes are similar.

[0100] To implement a subarray-based DFT beamforming scheme, this disclosure proposes various solutions for the UE to perform channel estimation (i.e., near-field channel estimation) and provide measurement results (e.g., CSI reports) to the BS, enabling the BS to determine the corresponding beamforming vector for each subarray of the antenna array based on the measurement results. Detailed solutions are described below.

[0101] According to some embodiments of this disclosure, the BS may transmit DL RS (e.g., CSI-RS) to the UE for channel estimation. DL RS may be transmitted on multiple DL RS resource sets. Each DL RS resource set may be associated with a corresponding subarray of the BS's antenna array (i.e., DL RS on the DL RS resource set is transmitted using the corresponding subarray associated with the DL RS resource set). For each DL RS resource set, different beamforming vectors (e.g., DFT-based beamforming vectors) are used to transmit the DL RS transmitted on different DL RS resources within the DL RS resource set. That is, each DL RS resource is associated with a corresponding beamforming vector applied to the corresponding subarray associated with the DL RS resource set.

[0102] For example, an antenna array is divided into K subarrays, and each subarray contains 2M+1 antenna elements. For subarray k, a DL RS resource set (called DL RS resource set k) containing multiple DL RS resources can be configured to transmit DL RS using subarray k. For example, the i-th DL RS transmitted by subarray k (called DL RS resource set k) It can be emitted on the i-th DL RS resource in the DL RS resource set k. DL It can use a phase gradient with DFT and phase shift beamforming vector To launch. In some embodiments, It can be equal to the phase of the central antenna element of subarray k, for example, the phase of the antenna element with index zero among the 2M+1 antenna elements of subarray k.

[0103] In some embodiments, a common phase offset can be used to transmit DL RSs on all DL RS resources across multiple DL RS resource sets; that is, different DL RSs transmitted from the same subarray or from different subarrays can have a common phase offset. In some embodiments, the common phase offset can be zero. That is, for all i and k, Although each DL RS transmits from all antenna elements in the subarray, each DL RS resource in the multiple DL RS resource set is a single-port DL RS resource. In other words, the entire subarray is virtualized as a single antenna port, where each of the subarrays transmits using a virtualized vector (i.e., a beamforming vector) for all i and k. .

[0104] In the embodiment, the subarray k is used to transmit DL. beamforming vector as follows:

[0105]

[0106] For K subarrays, a total of K DL RS resource sets can be configured. In some embodiments, the K DL RS resource sets can be jointly configured as a DL RS resource superset. Because antenna elements in the same subarray are used to transmit DL RS on different DL RS resources within the same DL RS resource set, different DL RS resources within the same DL RS resource set do not overlap in the time domain. Different DL RS resources in different DL RS resource sets can be associated with the same time domain resource or different time domain resources (e.g., symbols, time slots, etc.).

[0107] The BS may transmit configuration information indicating K DL RS resource sets to the UE, for example, via Radio Resource Control (RRC) configuration messages (e.g., CSI-ResourceConfig as specified in the 3GPP standard document) or other messages. The UE may perform channel estimation based on the configuration information, for example, receiving and measuring DL RS on the configured K DL RS resource sets.

[0108] For example, for a DL RS resource set k associated with a subarray k, the UE can measure the received signal strength (e.g., L1-RSRP) of the DL RS on each DL RS resource in the DL RS resource set k, and select the strongest DL RS (denoted as DL). For example, the DL RS with the highest L1-RSRP among all DL RSs received on DL RS resource set k. The DL RS resource on which the strongest DL RS is received can be called the strongest DL RS resource in DL RS resource set k. The index of the strongest DL RS or the strongest DL RS resource in DL RS resource set k can be represented as... As described above, each DL RS resource is associated with a corresponding beamforming vector for transmitting DL RS over that resource. Therefore, the beamforming vector used for transmitting DL RS... The beamforming vector is related to the DLRS resources in the DLRS resource set k. The associated beamforming vector can be expressed as: And has a DFT phase gradient (Assuming that for all i and k, the phase shift) ):

[0109]

[0110] For DL ​​RS resource set k, the UE can also measure DL. The received phase (represented as) Although the different antenna elements of the subarray use DL Different phases are transmitted, but the UE can approximately receive the combined signal from all antenna elements of the subarray as a plane wave, and measure a single phase as... .

[0111] To assist the BS in determining the optimal beamforming vector for each subarray, the UE may transmit a CSI report to the BS indicating the index and corresponding phase of the strongest DL RS resource in each of multiple DL RS resource sets, where the corresponding phase corresponds to the received phase of the DL RS on the strongest DL RS resource. For example, for subarray k, the CSI report may indicate (e.g., include) (For example, the CSI-RS Resource Indicator (CRI) of the strongest DL RS resource in DL RS resource set k) and In some embodiments, the corresponding phase indicated by the CSI report may be a relative phase, such as a phase offset relative to one (e.g., the largest) of the received phases of the DL RS on the strongest DL RS resource indicated by the CSI report. In some embodiments, the corresponding phase may be quantized using, for example, a 16PSK or 32PSK quantization scheme and transmitted in the CSI report.

[0112] As an example, the index of the strongest DL RS resource in the K subarrays can be reported as follows: ,in It is the index of the strongest DL RS resource of subarray j. The corresponding phases of the K subarrays can be reported as ,in Let be the relative phase of DL RS on the strongest DL RS resource of subarray j.

[0113] Figure 4 This describes the received phase of the corresponding strongest DL RS from multiple subarrays of an antenna array according to aspects of this disclosure.

[0114] exist Figure 4In the example described, the antenna array comprises five subarrays. The subarray indices are represented by horizontal coordinates, and the values ​​corresponding to the relative phases of the subarrays are represented by vertical coordinates. The relative phases corresponding to the five subarrays are [-2.5257, -0.6314, 0, -0.6314, -2.5257]. That is, the phase corresponding to subarray 3 is used as a reference for the relative phases, and its relative phase is 0. As depicted, subarray 3 has the largest phase, meaning that subarray 3 is the subarray closest to the UE. In embodiments, these relative phases can be quantized using, for example, a 16PSK or 32PSK quantization scheme and transmitted in the CSI report.

[0115] In some other embodiments, the UE may transmit phase values ​​in another form, for example, It can be included in a CSI report.

[0116] In some embodiments, the BS may transmit CSI report configuration to the UE, for example, via an RRC configuration message (e.g., CSI-ReportConfig as specified in a 3GPP standard document) or other messages. The CSI report configuration may be associated with multiple DL RS resource sets configured for DL ​​RS transmission and may instruct CSI reports based on measurements of DL RS on the multiple DL RS resource sets to indicate, for each DL RS resource set, the index of the strongest DL RS resource in the DL RS resource set and the corresponding phase of the DL RS on the strongest DL RS resource.

[0117] According to some embodiments of this disclosure, the CSI report format may be designed as follows:

[0118]

[0119] In the table above, CRI#k can be the CRI of the strongest DL RS resource in subarray k. CRI#k is the total number of DLRS resources in DLRS resource set k, and its bit width is [value missing]. Phase #k can be the corresponding phase of the DL RS on the strongest DL RS resource of subarray k. For N-PSK quantization, the bit width of phase #k is... ,and .

[0120] The BS can receive CSI reports from the UE, which indicate the subarray k. and , Then, BS can determine the DL RS resources in the DL RS resource set k of subarray k. Associated beamforming vector.

[0121] The beamforming vector of subarray k can be:

[0122]

[0123] The BS can use a subarray-based MRC scheme to transmit DL transmissions from K subarrays to the UE as follows: for each subarray used for DL ​​transmission, apply the beamforming vector associated with the strongest DL RS resource in the DL RS resource set associated with the subarray indicated by the CSI report, and the corresponding phase of the DL RS resource set associated with the subarray indicated by the CSI report:

[0124]

[0125] In some embodiments, DL transmission is the transmission of a new CSI-RS on a single CSI-RS resource using all subarrays of the antenna array. For example, the new CSI-RS could be a TRS for the UE to perform time and frequency tracking against the antenna array. In some embodiments, assuming the entire array is driven by a single time-domain resource or a single frequency resource, the UE can use the TRS to track the time and frequency deviations of the entire array.

[0126] As can be seen, based on feedback from the UE's CSI report, the BS can determine which beamforming vector to use and construct the transmit phase for each subarray and for each antenna element of the subarray.

[0127] Figure 5 This describes the transmit phase (denoted as subarray MRC) of antenna elements in an antenna array constructed based on a received CSI report according to an aspect of this disclosure, based on a subarray-based MRC scheme.

[0128] The antenna array can contain a total of 405 antenna elements, indexed from -202 to 202, and is divided into 5 subarrays, each containing 81 antenna elements. The antenna elements in the first subarray have indices ranging from -202 to -122; the antenna elements in the second subarray have indices ranging from -121 to -41; the antenna elements in the third subarray have indices ranging from -40 to 40; the antenna elements in the fourth subarray have indices ranging from 41 to 121; and the antenna elements in the fifth subarray have indices ranging from 122 to 202.

[0129] The index of the antenna element is represented by the horizontal coordinate, and the transmission phase of the antenna element is represented by the vertical coordinate. Figure 5 The transmit phase of an antenna element constructed based on an ideal MRC scheme (represented as ideal beamforming) is also shown for reference. It can be seen that the transmit phase constructed based on the ideal MRC scheme is similar to the transmit phase constructed based on a subarray-based MRC scheme.

[0130] Figure 6 This describes a comparison between the beam pattern of DL transmission using a subarray-based MRC scheme and an ideal beamforming pattern, according to aspects of this disclosure.

[0131] As can be seen, the two beam patterns are very close to each other, which indicates that subarray-based DFT beamforming can focus the DL signal to the UE and achieve the ideal MRC scheme.

[0132] Figure 7 An example of a UE 700 according to aspects of this disclosure is described. UE 700 may include at least one processor 702 and at least one memory 704. Furthermore, UE 700 may also include one or more of at least one controller 706 and at least one transceiver 708. The processor 702, memory 704, controller 706, or transceiver 708, or various combinations thereof, or various components thereof, may be examples of components for performing the various aspects of this disclosure as described herein. These components may be coupled via one or more interfaces (e.g., operatively, communicatively, functionally, electronically, electrically).

[0133] Processor 702, memory 704, controller 706, or transceiver 708, or various combinations or components thereof, may be implemented in hardware (e.g., a circuit system). The hardware may be a processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), or other programmable logic device, or any combination thereof configured or otherwise supporting components for performing the functions described in this disclosure.

[0134] Processor 702 may include intelligent hardware devices (e.g., a general-purpose processor, DSP, CPU, ASIC, FPGA, or any combination thereof). In some embodiments, processor 702 may be configured to operate memory 704. In some other embodiments, memory 704 may be integrated into processor 702. Processor 702 may be configured to execute computer-readable instructions stored in memory 704 to cause UE 700 to perform various functions of this disclosure.

[0135] Memory 704 may comprise volatile or non-volatile memory. Memory 704 may store computer-readable, computer-executable code containing instructions that, when executed by processor 702, cause UE 700 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as memory 704 or another type of memory. Computer-readable medium includes both non-transitory computer storage media and communication media, wherein the communication media includes any media that facilitates the transfer of a computer program from one place to another. Non-transitory storage media may be any available media accessible by a general-purpose or special-purpose computer.

[0136] In some embodiments, processor 702 and memory 704 coupled to processor 702 may be configured to cause UE 700 to perform one or more of the functions described herein (e.g., instructions stored in memory 704 are executed by processor 702). For example, processor 702 may support wireless communication at UE 700 according to examples disclosed herein. UE 700 may be configured to support components for performing the methods described in embodiments of this disclosure.

[0137] In an embodiment, processor 702 may be configured to cause UE 700 to: receive DLRS from BS on a plurality of DLRS resource sets, wherein each DLRS resource set is associated with a corresponding subarray of an antenna array, and for each DLRS resource set, DLRS on different DLRS resources in the DLRS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DLRS resource set; and transmit to BS a CSI report indicating, for each DLRS resource set in the plurality of DLRS resource sets, the index of the strongest DLRS resource in the DLRS resource set and the corresponding phase, wherein the DLRS of the strongest DLRS resource has the highest received strength among all DLRS on all DLRS resources in the DLRS resource set, and the corresponding phase corresponds to the received phase of the DLRS on the strongest DLRS resource.

[0138] Controller 706 manages the input and output signals of UE 700. Controller 706 can also manage peripheral devices not integrated into UE 700. In some embodiments, controller 706 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some embodiments, controller 706 may be implemented as part of processor 702.

[0139] In some embodiments, UE 700 may include at least one transceiver 708. In other embodiments, UE 700 may have more than one transceiver 708. Transceiver 708 may represent a wireless transceiver. Transceiver 708 may include one or more receiver chains 710, one or more transmitter chains 712, or a combination thereof.

[0140] Receiver chain 710 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, receiver chain 710 may include one or more antennas for receiving signals over the air or over a wireless medium. Receiver chain 710 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. Receiver chain 710 may include at least one demodulator configured to demodulate the received signal and obtain transmitted data by reversing the modulation technique applied during signal transmission. Receiver chain 710 may include at least one decoder for decoding the demodulated signal to receive transmitted data.

[0141] Transmitter chain 712 can be configured to generate and transmit signals (e.g., control information, data, packets). Transmitter chain 712 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques, such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase shift keying (PSK) or quadrature amplitude modulation (QAM). Transmitter chain 712 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over a wireless medium. Transmitter chain 712 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0142] Figure 8 An example of a processor 800 according to aspects of this disclosure is described. Processor 800 may be an example of a processor configured to perform various operations according to the examples described herein. Processor 800 may include a controller 802 configured to perform various operations according to the examples described herein. Processor 800 may optionally include at least one memory 804, which may be, for example, an L1 / L2 / L3 cache. Additionally or alternatively, processor 800 may optionally include one or more arithmetic logic units (ALUs) 806. One or more of these components may be electronically communicated or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses).

[0143] Processor 800 may be a processor chipset and includes a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receive, acquire, retrieve, transmit, output, forward, store, determine, identify, access, write, read) according to the examples described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory native to the processor chipset (e.g., processor 800) or contained within the processor chipset (e.g., processor 800)) or other memory (e.g., random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), static RAM (SRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase-change memory (PCM), and others).

[0144] Controller 802 can be configured to manage and coordinate various operations of processor 800 (e.g., signaling, receiving, acquiring, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, and reading) to enable processor 800 to support various operations according to the examples described herein. For example, controller 802 can operate as a control unit of processor 800, generating control signals that manage the operation of various components of processor 800. These control signals include enabling or disabling functional units, selecting data paths, initiating memory accesses, and coordinating operation timing.

[0145] Controller 802 may be configured to fetch (e.g., fetch, retrieve, receive) instructions from memory 804 and determine subsequent instructions to be executed to enable processor 800 to support various operations according to the examples described herein. Controller 802 may be configured to track the memory addresses of instructions associated with memory 804. Controller 802 may be configured to decode instructions to determine the operations to be performed and the operands involved. For example, controller 802 may be configured to interpret instructions and determine control signals to be output to other components of processor 800 to enable processor 800 to support various operations according to the examples described herein. Additionally or alternatively, controller 802 may be configured to manage data flow within processor 800. Controller 802 may be configured to control data transfers between registers, arithmetic logic unit (ALU), and other functional units of processor 800.

[0146] Memory 804 may include one or more caches (e.g., memory local to processor 800 or included in processor 800) or other memories, such as RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some embodiments, memory 804 may reside within or on the processor chipset (e.g., local to processor 800). In some other embodiments, memory 804 may reside outside the processor chipset (e.g., remote from processor 800).

[0147] Memory 804 may store computer-readable, computer-executable code containing instructions that, when executed by processor 800, cause processor 800 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as system memory or another type of memory. Controller 802 and / or processor 800 may be configured to execute computer-readable instructions stored in memory 804 to cause processor 800 to perform various functions. For example, processor 800 and / or controller 802 may be coupled to or coupled to memory 804, and processor 800, controller 802, and memory 804 may be configured to perform the various functions described herein. In some instances, processor 800 may include multiple processors, and memory 804 may include multiple memories. One or more of the multiple processors may be coupled to one or more of the multiple memories, which may be individually or collectively configured to perform the various functions described herein.

[0148] One or more ALU 806s may be configured to support various operations according to the examples described herein. In some embodiments, one or more ALU 806s may reside within or on a processor chipset (e.g., processor 800). In some other embodiments, one or more ALU 806s may reside outside the processor chipset (e.g., processor 800). One or more ALU 806s may perform one or more calculations on data, such as addition, subtraction, multiplication, and division. For example, one or more ALU 806s may receive input operands and an opcode that determines the operation to be performed. One or more ALU 806s may be configured with various logic and arithmetic circuitry, including adders, subtractors, shifters, and logic gates, to process and manipulate data according to the operation. Alternatively, one or more ALU 806s may support logical operations such as AND, OR, XOR, NOR, and NAND, enabling one or more ALU 806s to handle conditional operations, comparisons, and bitwise operations.

[0149] Processor 800 may support wireless communication according to examples disclosed herein. Processor 800 may be configured or operable to support components for performing the methods described in the embodiments of this disclosure.

[0150] In an embodiment, processor 800 may be adapted to a UE or a device with similar functionality. Controller 802 may be configured to cause processor 800 to: receive DL RS from BS on a plurality of DL RS resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, DL RS on different DL RS resources in the DL RS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DL RS resource set; and transmit to BS a CSI report indicating, for each DL RS resource set in the plurality of DL RS resource sets, the index of the strongest DL RS resource in the DL RS resource set and the corresponding phase, wherein the DL RS of the strongest DL RS resource has the highest received strength among all DL RS on all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the received phase of the DL RS on the strongest DL RS resource.

[0151] In an embodiment, processor 800 may be applicable to an NE (e.g., a base station) or a device with similar functionality. Controller 802 may be configured to cause processor 800 to: transmit DLRS to a UE on a plurality of DLRS resource sets, wherein each DLRS resource set is associated with a corresponding subarray of an antenna array, and for each DLRS resource set, the corresponding subarray associated with the DLRS resource set transmits DLRS on different DLRS resources within the DLRS resource set using different beamforming vectors; and receive from the UE a CSI report indicating, for each DLRS resource set in the plurality of DLRS resource sets, the index of the strongest DLRS resource in the DLRS resource set and the corresponding phase, wherein the DLRS of the strongest DLRS resource has the highest received strength among all DLRS on all DLRS resources in the DLRS resource set, and the corresponding phase corresponds to the received phase of the DLRS on the strongest DLRS resource.

[0152] Figure 9An example of an NE 900 (e.g., BS) according to aspects of this disclosure is described. The NE 900 may include at least one processor 902 and at least one memory 904. Furthermore, the NE 900 may also include one or more of at least one controller 906 and at least one transceiver 908. The processor 902, memory 904, controller 906, or transceiver 908, or various combinations thereof, or various components thereof, may be examples of components for performing the various aspects of this disclosure as described herein. These components may be coupled via one or more interfaces (e.g., operatively, communicatively, functionally, electronically, electrically).

[0153] Processor 902, memory 904, controller 906, or transceiver 908, or various combinations or components thereof, may be implemented in hardware (e.g., a circuit system). The hardware may be a processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), or other programmable logic device, or any combination thereof configured or otherwise supporting components for performing the functions described in this disclosure.

[0154] Processor 902 may include intelligent hardware devices (e.g., a general-purpose processor, DSP, CPU, ASIC, FPGA, or any combination thereof). In some embodiments, processor 902 may be configured to operate memory 904. In some other embodiments, memory 904 may be integrated into processor 902. Processor 902 may be configured to execute computer-readable instructions stored in memory 904 to cause NE 900 to perform various functions of this disclosure.

[0155] Memory 904 may comprise volatile or non-volatile memory. Memory 904 may store computer-readable, computer-executable code containing instructions that, when executed by processor 902, cause NE 900 to perform the various functions described herein. The code may be stored in a non-transitory computer-readable medium, such as memory 904 or another type of memory. Computer-readable medium includes both non-transitory computer storage media and communication media, wherein the communication media includes any media that facilitates the transfer of a computer program from one place to another. Non-transitory storage media may be any available media accessible by a general-purpose or special-purpose computer.

[0156] In some embodiments, processor 902 and memory 904 coupled to processor 902 may be configured to cause NE 900 to perform one or more of the functions described herein (e.g., processor 902 executing instructions stored in memory 904). For example, processor 902 may support wireless communication at NE 900 according to examples disclosed herein. NE 900 may be configured to support components for performing the methods described in embodiments of this disclosure.

[0157] In an embodiment, processor 902 may be configured to cause NE 900 to: transmit DLRS to UE on a plurality of DLRS resource sets, wherein each DLRS resource set is associated with a corresponding subarray of an antenna array, and for each DLRS resource set, the corresponding subarray associated with the DLRS resource set uses different beamforming vectors to transmit DLRS transmitted on different DLRS resources in the DLRS resource set; and receive from UE a CSI report indicating, for each DLRS resource set in the plurality of DLRS resource sets, the index of the strongest DLRS resource in the DLRS resource set and the corresponding phase, wherein the DLRS of the strongest DLRS resource has the highest received strength among all DLRS on all DLRS resources in the DLRS resource set, and the corresponding phase corresponds to the received phase of the DLRS on the strongest DLRS resource.

[0158] Controller 906 manages the input and output signals of NE 900. Controller 906 can also manage peripheral devices not integrated into NE 900. In some embodiments, controller 906 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some embodiments, controller 906 may be implemented as part of processor 902.

[0159] In some embodiments, the NE 900 may include at least one transceiver 908. In other embodiments, the NE 900 may have more than one transceiver 908. The transceiver 908 may represent a wireless transceiver. The transceiver 908 may include one or more receiver chains 910, one or more transmitter chains 912, or a combination thereof.

[0160] Receiver chain 910 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, receiver chain 910 may include one or more antennas for receiving signals over the air or over a wireless medium. Receiver chain 910 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. Receiver chain 910 may include at least one demodulator configured to demodulate the received signal and obtain transmitted data by reversing the modulation technique applied during signal transmission. Receiver chain 910 may include at least one decoder for decoding the demodulated signal to receive transmitted data.

[0161] Transmitter chain 912 can be configured to generate and transmit signals (e.g., control information, data, packets). Transmitter chain 912 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques, such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase shift keying (PSK) or quadrature amplitude modulation (QAM). Transmitter chain 912 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over a wireless medium. Transmitter chain 912 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0162] Figure 10 A flowchart illustrating an exemplary method according to aspects of this disclosure is provided. The operation of the method can be implemented by a UE as described herein. In some embodiments, the UE can execute a set of instructions to control functional elements of the UE to perform the described functions.

[0163] At 1002, the method may include receiving DL RS from the BS on multiple DL RS resource sets, wherein each DL RS resource set is associated with a corresponding subarray of the antenna array, and for each DL RS resource set, the DL RS on different DL RS resources within the DL RS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DL RS resource set. The operation of 1002 may be performed according to the examples described herein. In some embodiments, it may be performed by reference to... Figure 7 The described aspect of the UE performing the operation of 1002. In some embodiments, the DL RS may be a CSI-RS, and multiple DL RS resource sets may be multiple CSI-RS resource sets.

[0164] At 1004, the method may include transmitting to the BS a CSI report indicating, for each of a plurality of DL RS resource sets, the index of the strongest DL RS resource in the DL RS resource set and its corresponding phase, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource. The operation at 1004 may be performed according to the examples described herein. In some embodiments, it may be performed by reference to... Figure 7 The described aspect of the UE to perform the operation of 1004.

[0165] In some embodiments, different DL RS resources in the same DL RS resource set do not overlap in the time domain, and different DL RS resources in different DL RS resource sets are associated with the same time domain resource or different time domain resources.

[0166] In some embodiments, each DL RS resource in a plurality of DL RS resource sets is a single-port DL RS resource.

[0167] In some embodiments, the method may further include receiving configuration information from the BS indicating multiple DL RS resource sets.

[0168] In some embodiments, the method may further include receiving a CSI report configuration associated with a plurality of DL RS resource sets from a BS, wherein the CSI report configuration indicates that a CSI report based on measurements of DL RS on the plurality of DL RS resource sets indicates, for each DL RS resource set, the index and corresponding phase of the strongest DL RS resource in the DL RS resource set.

[0169] In some embodiments, each corresponding phase indicated by the CSI report is a phase offset relative to one of the received phases of the DL RS on the strongest DL RS resource indicated by the CSI report.

[0170] In some embodiments, one of them is the maximum received phase among all DL RSs on the strongest DL RS resource indicated by the CSI report.

[0171] In some embodiments, the corresponding phase indicated by the CSI report is quantized.

[0172] In some embodiments, the method may further include: receiving from the BS a DL transmission using a subarray-based MRC scheme based on a CSI report, wherein for each subarray used for DL ​​transmission, a beamforming vector associated with the strongest DL RS resource in the DL RS resource set associated with the subarray indicated by the CSI report, and a corresponding phase of the DL RS resource set associated with the subarray indicated by the CSI report, are applied.

[0173] In some embodiments, DL transmission is the transmission of CSI-RS on a single CSI-RS resource using all subarrays of the antenna array.

[0174] In some embodiments, CSI-RS is a TRS for the UE to perform time and frequency tracking of the antenna array.

[0175] It should be noted that the method described herein describes one possible implementation, and the operation and steps may be rearranged or otherwise modified, and other implementations are possible.

[0176] Figure 11 A flowchart illustrating an exemplary method according to aspects of this disclosure is provided. The operation of the method may be implemented by an NE (e.g., a BS) as described herein. In some embodiments, the NE may execute a set of instructions to control the functional elements of the NE to perform the described functions.

[0177] At 1102, the method may include transmitting DLRS to the UE on multiple DLRS resource sets, wherein each DLRS resource set is associated with a corresponding subarray of an antenna array, and for each DLRS resource set, the corresponding subarray associated with the DLRS resource set transmits DLRS transmitted on different DLRS resources within the DLRS resource set using different beamforming vectors. The operation of 1102 may be performed according to the examples described herein. In some embodiments, it may be performed by reference to... Figure 9 The described NE is used to perform the operation of 1102.

[0178] At 1104, the method may include receiving from the UE a CSI report indicating, for each of a plurality of DL RS resource sets, the index of the strongest DL RS resource in the DL RS resource set and the corresponding phase, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource. The operation of 1104 may be performed according to the examples described herein. In some embodiments, it may be performed by reference to... Figure 9 The described NE is used to perform the operation of 1104.

[0179] In some embodiments, a common phase offset is used to transmit DL RS on all DL RS sources in multiple DL RS resource sets.

[0180] In some embodiments, the common phase offset is zero.

[0181] In some embodiments, different DL RS resources in the same DL RS resource set do not overlap in the time domain, and different DL RS resources in different DL RS resource sets are associated with the same time domain resource or different time domain resources.

[0182] In some embodiments, each DL RS resource in a plurality of DL RS resource sets is a single-port DL RS resource.

[0183] In some embodiments, the method may further include transmitting configuration information to the UE indicating multiple DL RS resource sets.

[0184] In some embodiments, the method may further include transmitting a CSI report configuration associated with a plurality of DL RS resource sets to the UE, wherein the CSI report configuration indicates that a CSI report based on measurements of DL RS on the plurality of DL RS resource sets indicates, for each of the plurality of DL RS resource sets, the index of the strongest DL RS resource in the DL RS resource set and its corresponding phase.

[0185] In some embodiments, each corresponding phase indicated by the CSI report is a phase offset relative to one of the received phases of the DL RS on the strongest DL RS resource indicated by the CSI report.

[0186] In some embodiments, one of them is the maximum received phase among all DL RSs on the strongest DL RS resource indicated by the CSI report.

[0187] In some embodiments, the corresponding phase indicated by the CSI report is quantized.

[0188] In some embodiments, the method may further include: transmitting DL transmission to the UE using a subarray-based MRC scheme based on CSI reports, wherein for each subarray used for DL ​​transmission, a beamforming vector associated with the strongest DL RS resource in the DL RS resource set associated with the subarray indicated by the CSI report, and a corresponding phase of the DL RS resource set associated with the subarray indicated by the CSI report, are applied.

[0189] In some embodiments, DL transmission is the transmission of CSI-RS on a single CSI-RS resource using all subarrays of the antenna array.

[0190] In some embodiments, CSI-RS is a TRS for the UE to perform time and frequency tracking of the antenna array.

[0191] It should be noted that the methods described herein describe possible implementations, and the operations and steps may be rearranged or otherwise modified, and other implementations are possible.

[0192] The description herein is provided to enable those skilled in the art to make or use this disclosure. Various modifications to this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but should be given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A base station (BS) for wireless communication, comprising: At least one memory; and At least one processor, coupled to the at least one memory and configured to enable the BS to: DL RS are transmitted to a User Equipment (UE) on multiple downlink DL reference signal (DL RS) resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, the corresponding subarray associated with the DL RS resource set uses different beamforming vectors to transmit DL RS transmitted on different DL RS resources within the DL RS resource set; and The UE receives a Channel State Information (CSI) report indicating the index and corresponding phase of the strongest DL RS resource in each of the plurality of DL RS resource sets, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource.

2. The BS of claim 1, wherein a common phase offset is used to transmit the DL RS on all DL RS sources in the plurality of DL RS resource sets.

3. The BS according to claim 2, wherein the common phase offset is zero.

4. The BS according to claim 1, wherein different DL RS resources in the same DL RS resource set do not overlap in the time domain, and different DL RS resources in different DL RS resource sets are associated with the same time domain resource or different time domain resources.

5. The BS according to claim 1, wherein each DL RS resource in the plurality of DL RS resource sets is a single-port DL RS resource.

6. The BS of claim 1, wherein the at least one processor is further configured to cause the BS to: The UE is transmitted configuration information indicating the multiple DL RS resource sets.

7. The BS of claim 6, wherein the at least one processor is further configured to cause the BS to: The UE is transmitted a CSI report configuration associated with the plurality of DL RS resource sets, wherein the CSI report configuration indicates, based on the measurement of DL RS on the plurality of DL RS resource sets, the index and the corresponding phase of the strongest DL RS resource in the DL RS resource set for each of the plurality of DL RS resource sets.

8. The BS of claim 1, wherein each corresponding phase indicated by the CSI report is a phase offset relative to one of the received phases of the DL RS on the strongest DL RS resource indicated by the CSI report.

9. The BS of claim 8, wherein one of them is the maximum received phase among all the DL RSs on the strongest DL RS resource indicated by the CSI report.

10. The BS of claim 1, wherein the corresponding phase indicated by the CSI report is quantized.

11. The BS of claim 1, wherein the at least one processor is further configured to cause the BS to: The UE is transmitted using a subarray-based maximum ratio combining MRC scheme based on the CSI report, wherein for each subarray used for the DL transmission, a beamforming vector associated with the strongest DL RS resource in the DL RS resource set associated with the subarray indicated by the CSI report, and the corresponding phase of the DL RS resource set associated with the subarray indicated by the CSI report are applied.

12. The BS of claim 11, wherein the DL transmission is a CSI-RS transmission using all subarrays of the antenna array on a single CSI-RS resource.

13. The BS according to claim 12, wherein the CSI-RS is a tracking RS (TRS) for the UE to perform time and frequency tracking of the antenna array.

14. A user equipment (UE) for wireless communication, comprising: At least one memory; and At least one processor, coupled to and configured to enable the UE to: DL RS are received from a base station (BS) on multiple downlink DL reference signal (RS) resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, the DL RS on different DL RS resources within the DL RS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DL RS resource set; and The BS transmits a Channel State Information (CSI) report to each of the plurality of DL RS resource sets, indicating the index of the strongest DL RS resource in the DL RS resource set and the corresponding phase, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource.

15. The UE of claim 14, wherein the at least one processor is further configured to cause the UE to: DL RS measurements are performed on all DL RS resources in the plurality of DL RS resource sets to determine the strongest DL RS resource and the corresponding phase for each DL RS resource set.

16. The UE according to claim 14, wherein different DL RS resources in the same DL RS resource set do not overlap in the time domain, and different DL RS resources in different DL RS resource sets are associated with the same time domain resource or different time domain resources.

17. The UE of claim 14, wherein the at least one processor is further configured to cause the UE to: The BS receives configuration information indicating the plurality of DL RS resource sets.

18. The UE of claim 17, wherein the at least one processor is further configured to cause the UE to: The BS receives a CSI report configuration associated with the plurality of DL RS resource sets, wherein the CSI report configuration indicates, based on measurements of DL RS on the plurality of DL RS resource sets, that a CSI report for each DL RS resource set indicates the index and the corresponding phase of the strongest DL RS resource in the DL RS resource set.

19. A processor for wireless communication, comprising: At least one controller, coupled to at least one memory and configured to enable the processor to: DL RS are transmitted to a User Equipment (UE) on multiple downlink DL reference signal (DL RS) resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, the corresponding subarray associated with the DL RS resource set uses different beamforming vectors to transmit DL RS transmitted on different DL RS resources within the DL RS resource set; and The UE receives a Channel State Information (CSI) report indicating the index and corresponding phase of the strongest DL RS resource in each of the plurality of DL RS resource sets, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource.

20. A processor for wireless communication, comprising: At least one controller, coupled to at least one memory and configured to enable the processor to: DL RS are received from a base station (BS) on multiple downlink DL reference signal (RS) resource sets, wherein each DL RS resource set is associated with a corresponding subarray of an antenna array, and for each DL RS resource set, the DL RS on different DL RS resources within the DL RS resource set are associated with different beamforming vectors applied to the corresponding subarray associated with the DL RS resource set; and The BS transmits a Channel State Information (CSI) report to each of the plurality of DL RS resource sets, indicating the index of the strongest DL RS resource in the DL RS resource set and the corresponding phase, wherein the DL RS of the strongest DL RS resource has the highest receive strength among all DL RS resources in the DL RS resource set, and the corresponding phase corresponds to the receive phase of the DL RS on the strongest DL RS resource.

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