Beamforming circuitry for multiple antennas

Abstract

An apparatus and method for multi-antenna wireless communication are provided. In one aspect, one or more input ports of a first-layer two-dimensional (2D) Butler matrix are selected for communication of one or more streams via one or more beams by an array antenna. A control signal is applied to a control input pin of a first-layer-second-layer switch, and the first-layer-second-layer switch is configurable to selectively connect first-layer output ports of the first-layer 2D Butler matrix to at least a subset of second-layer input ports of the second-layer 2D Butler matrix based on the control signal. The one or more streams are then transmitted or received via one or more beams by the array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-layer 2D Butler matrix.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of U.S. patent application Ser. No. 16 / 993,903, filed Aug. 14, 2020, entitled "BEAMFORMING CIRCUIT FOR MULTIPLE ANTENNAS," which is assigned to the assignee of the present application and incorporated by reference in its entirety.

[0002] TECHNICAL FIELD This disclosure relates generally to communication systems, and more particularly to techniques related to beamforming. [Background technology]

[0003] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may utilize multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0004] These multiple access technologies are being adopted in various telecommunications standards to provide common protocols that enable different wireless devices to communicate on a city, national, regional, or even global scale. An exemplary telecommunications standard is 5G New Radio (NR). 5G NR is part of the ongoing mobile broadband evolution promulgated by the 3rd Generation Partnership Project (3GPP®) to meet new requirements related to latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. Further improvements are needed in 5G NR technology. These improvements may also be applicable to other multiple access technologies and telecommunications standards utilizing these technologies. Summary of the Invention [Means for solving the problem]

[0005] 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, nor is it intended to identify key or critical elements of all aspects or delineate 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.

[0006] Aspects of the present disclosure provide a method, a computer-readable medium, and an apparatus.

[0007] In one aspect, an apparatus for multi-antenna wireless communication includes a first layer two-dimensional (2D) Butler matrix having first layer input ports and first layer output ports. The apparatus further includes a second layer 2D Butler matrix having second layer input ports and second layer output ports. The apparatus further includes a first-layer-second layer switch, the first-layer-second layer switch being configurable to selectively connect the first layer output ports of the first layer 2D Butler matrix to at least a subset of the second layer input ports of the second layer 2D Butler matrix based on a control signal applied to a control input pin of the first-layer-second layer switch.

[0008] In another aspect, a method of multi-antenna wireless communication includes selecting one or more input ports of a first-layer 2D Butler matrix for communication of one or more streams via one or more beams by an array antenna. The method further includes applying a control signal to a control input pin of a first-layer-second-layer switch, the first-layer-second-layer switch being configurable to selectively connect first-layer output ports of the first-layer 2D Butler matrix to at least a subset of second-layer input ports of the second-layer 2D Butler matrix based on the control signal. The method further includes transmitting or receiving the one or more streams via the one or more beams by the array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-layer 2D Butler matrix.

[0009] In one aspect, an apparatus for wireless communication includes a transceiver, a memory configured to store instructions, and one or more processors communicatively coupled to the transceiver and the memory. The one or more processors are configured to execute the instructions for implementing multi-antenna wireless communication, including selecting one or more input ports of a first tier 2D Butler matrix for communication of one or more streams via one or more beams by an array antenna, applying control signals to control input pins of a first-tier-second tier switch, the first-tier-second tier switch being configurable to selectively connect first-tier output ports of the first tier 2D Butler matrix to at least a subset of second-tier input ports of a second tier 2D Butler matrix based on the control signals, and transmitting or receiving the one or more streams via the one or more beams by the array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second tier 2D Butler matrix.

[0010] In a further aspect, an apparatus for multi-antenna wireless communication includes means for selecting one or more input ports of a first layer 2D Butler matrix for communication of one or more streams via one or more beams by an array antenna. The apparatus further includes means for applying a control signal to a control input pin of a first layer-to-second layer switch, the first layer-to-second layer switch being configurable to selectively connect first layer output ports of the first layer 2D Butler matrix to at least a subset of second layer input ports of the second layer 2D Butler matrix based on the control signal. The apparatus further includes means for transmitting or receiving one or more streams via one or more beams by the array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second layer 2D Butler matrix.

[0011] In another aspect, a non-transitory computer-readable storage medium includes code executable by one or more processors to implement multi-antenna wireless communication, including selecting one or more input ports of a first-tier 2D Butler matrix for communication of one or more streams via one or more beams by an array antenna; applying control signals to control input pins of a first-tier-second-tier switch, the first-tier-second-tier switch being configurable to selectively connect first-tier output ports of the first-tier 2D Butler matrix to at least a subset of second-tier input ports of the second-tier 2D Butler matrix based on the control signals; and transmitting or receiving the one or more streams via the one or more beams by the array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-tier 2D Butler matrix.

[0012] To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of the various aspects may be employed, and the description is intended to include all such aspects and their equivalents. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 illustrates an example of a wireless communication system and access network including components for beamforming, in accordance with various aspects of the present disclosure. [Figure 2A] FIG. 2 illustrates an example of a first frame, according to various aspects of the present disclosure. [Figure 2B] FIG. 1 illustrates an example of a DL channel within a subframe, in accordance with various aspects of the present disclosure. [Figure 2C]FIG. 10 illustrates an example of a second frame, according to various aspects of the present disclosure. [Figure 2D] FIG. 1 illustrates an example of an UL channel within a subframe, in accordance with various aspects of the present disclosure. [Figure 3] FIG. 2 is a schematic diagram illustrating a first exemplary beamforming circuit according to various aspects of the present disclosure. [Figure 4] FIG. 10 is a schematic diagram illustrating a second exemplary beamforming circuit according to various aspects of the present disclosure. [Figure 5] 5A-5C illustrate example beam patterns generated by an array antenna in response to activation of input ports in the second example beamforming circuit of FIG. 4 in accordance with various aspects of the present disclosure. [Figure 6] FIG. 10 is a schematic diagram illustrating a third exemplary beamforming circuit according to various aspects of the present disclosure. [Figure 7] FIG. 10 is a schematic diagram illustrating a fourth exemplary beamforming circuit according to various aspects of the present disclosure. [Figure 8] FIG. 10 is a schematic diagram illustrating a fifth exemplary beamforming circuit according to various aspects of the present disclosure. [Figure 9] 1 is a flowchart illustrating an example method for multi-antenna wireless communication, in accordance with various aspects of the present disclosure. [Figure 10] FIG. 2 is a block diagram illustrating example components of an example UE, in accordance with various aspects of the present disclosure. [Figure 11] FIG. 2 illustrates example components of a base station and a UE in an access network, in accordance with various aspects of the present disclosure. [Figure 12] FIG. 2 is a block diagram illustrating example components of an example base station, in accordance with various aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] The detailed description set forth below, along with the accompanying drawings, is intended as a description of various configurations and does not represent the only configuration in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts. The following description may focus on 5G NR, but the concepts described herein may be applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0015] This embodiment relates to a three-dimensional (3D) Butler matrix configured for beam steering across an array antenna. The 3D Butler matrix includes a first-layer two-dimensional (2D) Butler matrix, a second-layer 2D Butler matrix, and a first-layer-second-layer switch that selectively connects the first-layer 2D Butler matrix to the second-layer 2D Butler matrix. More specifically, the first-layer-second-layer switch is controllable via control signals applied to control input pins of the first-layer-second-layer switch to selectively connect output ports of the first-layer 2D Butler matrix to at least a subset of input ports of the second-layer 2D Butler matrix, each output port of the second-layer 2D Butler matrix being associated with one antenna element in the 2D array antenna. In some embodiments, each input port of the first-layer 2D Butler matrix is ​​associated with a desired beam azimuth or elevation angle, and each control signal value applied to the control input pin of the first-layer-second-layer switch is also associated with a desired beam azimuth or elevation angle. In some embodiments, for example, the first layer 2D Butler matrix and the second layer 2D Butler matrix each can include one or more circuitry and / or radio frequency (RF) components. Further details of the 3D Butler matrix are described below with reference to various embodiments.

[0016] Several aspects of telecommunications systems are presented below with reference to various apparatus and methods. These apparatus and methods are described in the detailed description that follows and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0017] As an example, an element or any portion of an element or any combination of elements may be implemented as a "processing system" including 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-chips (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gate logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout this disclosure. One or more processors in a processing system may execute software. Software may be broadly interpreted 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, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0018] Thus, in one or more exemplary aspects, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may comprise random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the above 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.

[0019] 1 illustrates an example wireless communication system and access network 100 including a UE 104 and / or a base station 102 configured for beamforming in multi-antenna wireless communication. More specifically, the UE 104 or base station 102 may include a modem 140 that controls a 3D Butler matrix 145 configured to perform beam steering across a 2D array antenna 144. The 3D Butler matrix 145 includes a first layer 2D Butler matrix 141, a first layer-to-second layer switch 142, and a second layer 2D Butler matrix 143. Modem 140 controls first-to-second layer switch 142 (via control signals applied to control input pins of first-to-second layer switch 142) to selectively connect output ports of first layer 2D Butler matrix 141 to at least a subset of input ports of second layer 2D Butler matrix 143, each output port of second layer 2D Butler matrix 143 being associated with one antenna element in 2D array antenna 144. Further details of this embodiment are described below.

[0020] The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., 5G core (5GC)). The base station 102 may include a macrocell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macrocell includes a base station. A small cell includes a femtocell, a picocell, and a microcell.

[0021] A base station 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 through a backhaul link 132 (e.g., an S1 interface). A base station 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with the core network 190 through a backhaul link 184. In addition to other functions, the base station 102 may perform one or more of the following functions: forwarding of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast services (MBMS), subscriber and device tracking, RAN information management (RIM), paging, positioning, and delivery of alert messages. The base stations 102 may communicate with each other directly or indirectly (e.g., through the EPC 160 or the core network 190) via backhaul links 134 (e.g., X2 interfaces). The backhaul links 132, 134, and 184 may be wired or wireless.

[0022] The base stations 102 may communicate wirelessly with the UEs 104. Each of the base stations 102 may provide communication coverage in a respective geographic coverage area 110. Overlapping geographic coverage areas 110 may exist. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells may be known as a heterogeneous network. A heterogeneous network may also include a Home evolved Node B (eNB) (HeNB), which may serve restricted groups known as Closed Subscriber Groups (CSGs). The communication link 120 between the base station 102 and the UE 104 may include uplink (UL) (also referred to as reverse link) transmissions from the UE 104 to the base station 102 and / or downlink (DL) (also referred to as forward link) transmissions from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link may be over one or more carriers. The base station 102 / UE 104 may use spectrum with a bandwidth of up to Y MHz per carrier (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) allocated in carrier aggregation with up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. The carrier allocation may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0023] Several UEs 104 may communicate with each other using device-to-device (D2D) communication links 158, including, for example, synchronization signals. The D2D communication links 158 may use DL / UL WWAN spectrum. The D2D communication links 158 may 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 a physical sidelink control channel (PSCCH). The D2D communication may be over various wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0024] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152, such as in the 5 GHz unlicensed frequency spectrum, via a communication link 154. When communicating in the unlicensed frequency spectrum, the STA 152 / AP 150 may perform clear channel assessment (CCA) before communicating to determine whether a channel is available.

[0025] The small cell 102' may operate in licensed and / or unlicensed frequency spectrum. When operating in the unlicensed frequency spectrum, the small cell 102' may utilize NR and may use the same unlicensed frequency spectrum (e.g., 5 GHz) as may be used by the Wi-Fi AP 150. A small cell 102' utilizing NR in the unlicensed frequency spectrum may enhance coverage to and / or increase capacity of the access network.

[0026] The electromagnetic spectrum is often subdivided into various classes, bands, channels, etc. based on frequency / wavelength. For 5G NR, two initial operating bands have been identified, designated by the frequency range designations FR1 (410 MHz to 7.125 GHz) and FR2 (24.25 GHz to 52.6 GHz). Frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Although portions of FR1 are above 6 GHz, FR1 is often referred to (interchangeably) as the "sub-6 GHz" band in various documents and papers. Similar nomenclature issues arise with FR2, which is often referred to (interchangeably) as the "mmWave" band in documents and papers, even though it differs from the extremely high frequency (EHF) band (30 GHz to 300 GHz) identified as the "mmWave" band by the International Telecommunications Union (ITU).

[0027] With the above aspects in mind, it should be understood that unless otherwise specified, terms such as "sub-6 GHz," when used herein, may broadly refer to frequencies that may be below 6 GHz, may be within FR1, or may include mid-band frequencies. Additionally, it should be understood that unless otherwise specified, terms such as "mm-wave," when used herein, may broadly refer to frequencies that may include mid-band frequencies, may be within FR2, or may be within the EHF band.

[0028] The base station 102, whether a small cell 102′ or a large cell (e.g., a macro base station), may include an eNB, a gNodeB (gNB), or another type of base station. Some base stations, such as the gNB 180, communicate with the UE 104 and may operate in the conventional sub-6 GHz spectrum, at mmWave frequencies, and / or at quasi-mmWave frequencies. When the gNB 180 operates in mmWave frequencies or quasi-mmWave frequencies, the gNB 180 may be referred to as a mmWave base station. The mmWave base station 180 may use beamforming 182 with the UE 104 to compensate for path loss and short distances.

[0029] The base station 180 may transmit beamformed signals to the UE 104 in one or more transmit directions 182′. The UE 104 may receive beamformed signals from the base station 180 in one or more receive directions 182″. The UE 104 may also transmit beamformed signals to the base station 180 in one or more transmit directions. The base station 180 may receive beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of the base station 180 / UE 104. The transmit direction and receive direction for the base station 180 may or may not be the same. The transmit direction and receive direction for the UE 104 may or may not be the same.

[0030] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may be in communication with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Generally, the MME 162 handles bearer and connection management. All user Internet Protocol (IP) packets are forwarded through the serving gateway 166, which is itself connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to an IP service 176. The IP services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within the public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway 168 may be used to deliver MBMS traffic to base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area that broadcasts a particular service, and may be responsible for session management (start / stop) and collecting eMBMS-related charging information.

[0031] The core network 190 may include an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are forwarded through the UPF 195. The UPF 195 provides IP address allocation for the UE as well as other functions. The UPF 195 is connected to IP services 197. The IP services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services, and / or other IP services.

[0032] The base station 102 may also be referred to as a gNB, Node B, evolved Node B (eNB), access point, base transceiver station, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmit reception point (TRP), or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or core network 190 for the UE 104. Examples of the UE 104 include a mobile phone, a smartphone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small cooking appliance, a health management device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, toasters, vehicles, heart monitors, etc.) The UEs 104 may also be referred to as stations, mobile stations, subscriber stations, mobile units, subscriber units, wireless units, remote units, mobile devices, wireless devices, wireless communication devices, remote devices, mobile subscriber stations, access terminals, mobile terminals, wireless terminals, remote terminals, handsets, user agents, mobile clients, clients, or some other suitable terminology.

[0033] 2A-2D, one or more example frame structures, channels, and resources may be used for communications between the base station 102 and the UE 104 of FIG. 1. FIG. 2A is a diagram 200 illustrating an example of a first subframe in a 5G / NR frame structure. FIG. 2B is a diagram 230 illustrating an example of a DL channel in a 5G / NR subframe. FIG. 2C is a diagram 250 illustrating an example of a second subframe in a 5G / NR frame structure. FIG. 2D is a diagram 280 illustrating an example of a UL channel in a 5G / NR subframe. The 5G / NR frame structure may be FDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated to either DL or UL, or TDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated to both DL and UL. In the examples provided by Figures 2A and 2C, the 5G / NR frame structure is assumed to be TDD, subframe 4 is configured using slot format 28 (with mostly DL), where D is DL, U is UL, and X is flexible for use between DL / UL, and subframe 3 is configured using slot format 34 (with mostly UL). Subframes 3 and 4 are shown using slot formats 34 and 28, respectively, but any particular subframe may be configured using any of the various available slot formats 0 through 61. Slot formats 0 and 1 are all DL and UL, respectively. The other slot formats 2 through 61 contain a mix of DL, UL, and flexible symbols. The UE is configured with the slot format (dynamically through DL control information (DCI) or semi-statically / statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI). Note that the following description also applies to 5G / NR frame structures that are TDD.

[0034] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10 ms) may be divided into 10 equal-sized subframes (1 ms). Each subframe may include one or more time slots. A subframe may also include a minislot, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. Symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Symbols on the UL may be CP-OFDM symbols (for high-throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also called single-carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios and limited to single-stream transmission). The number of slots in a subframe is based on the slot configuration and numerology. In slot configuration 0, the different numerologies μ 0-5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. In slot configuration 1, the different numerologies 0-2 allow 2, 4, and 8 slots per subframe, respectively. Therefore, for slot configuration 0 and numerology μ, 14 symbols / slot and 2 μ There are slots / subframes. Subcarrier spacing and symbol length / duration are functions of numerology. Subcarrier spacing is 2 μ * may be equal to 15 kHz, where μ is a numerology between 0 and 5. Thus, numerology μ=0 has a subcarrier spacing of 15 kHz, and numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length / duration is inversely proportional to the subcarrier spacing. Figures 2A-2D give an example of slot configuration 0 with 14 symbols per slot and numerology μ=0 with 1 slot per subframe. The subcarrier spacing is 15 kHz, and the symbol duration is approximately 66.7 μs.

[0035] A resource grid can be used to represent the frame structure. Each time slot contains a resource block (RB) (also called a physical RB (PRB)) that spans 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (RE). The number of bits carried by each RE depends on the modulation scheme.

[0036] As shown in Figure 2A, some of the REs carry reference (pilot) signals (RS) for the UE. The RSs are also called demodulation RSs (DM-RSs) (for a particular configuration, 100x is the port number) for channel estimation at the UE. x , but other DM-RS configurations are possible), and channel state information reference signals (CSI-RS). The RSs may also include beam measurement RSs (BRSs), beam refinement RSs (BRRSs), and phase tracking RSs (PT-RSs).

[0037] FIG. 2B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each containing nine RE groups (REGs), with each REG containing four consecutive REs within an OFDM symbol. A primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of the frame. The PSS is used by the UE 104 to determine subframe / symbol timing and physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of the frame. The SSS is used by the UE to determine the physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the DM-RS described above. The Physical Broadcast Channel (PBCH), which carries the Master Information Block (MIB), may be logically grouped with the PSS and SSS to form the Synchronization Signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth and the System Frame Number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information not transmitted over the PBCH, such as System Information Blocks (SIBs), and paging messages.

[0038] As shown in Figure 2C, some of the REs carry DM-RS (denoted as R for one particular configuration, although other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether a short or long PUCCH is transmitted and the particular PUCCH format used. Although not shown, the UE may transmit a sounding reference signal (SRS). The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0039] 2D shows an example of various UL channels within a subframe of a frame. The PUCCH, in one configuration, may be located as shown. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQIs), precoding matrix indicators (PMIs), rank indicators (RIs), and HARQ ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry buffer status reports (BSRs), power headroom reports (PHRs), and / or UCI.

[0040] In some aspects, to provide higher throughput at lower cost, multiple links can be used per panel (e.g., per antenna area), with each link separated from other links by a different plane wave arrival angle. These aspects may be applicable, for example, to sub-THz communications (e.g., 140 GHz or 300 GHz), where relatively low wavelengths allow the use of relatively small antennas and relatively small antenna-to-antenna distances, thereby enabling a larger number of antennas to be used and supporting more links with narrower beams and higher spatial separation between beams, thereby enabling better spectral efficiency. In one non-limiting aspect, for example, all links associated with a panel may be configured to have orthogonal patterns. In one embodiment, such links can be provided using a Butler matrix, a beamformer circuit configured to provide a uniform distribution and constant phase difference between adjacent antenna elements in an array antenna.

[0041] In one aspect, the Butler matrix may be implemented using interconnected phase adjusters and hybrid couplers. However, this aspect is not so limited, and the Butler matrix may be implemented in alternative aspects using fewer component types (e.g., using only hybrid couplers) or more component types (e.g., phase adjusters, hybrid couplers, and crossover circuits). In one aspect, for example, to transmit RF signals via an array antenna, a modem can select one or more ports of the Butler matrix such that the Butler matrix receives one or more signals on one or more ports of the Butler matrix and generates output signals having different phases on opposing ports for transmission via multiple antenna elements coupled to the opposing ports. The Butler matrix can also provide reciprocity functionality for receiving RF signals. For example, the Butler matrix can receive RF signals having different phases via multiple ports coupled to multiple antenna elements, and then phase-shift and combine the RF signals to provide one or more signals on one or more opposing ports selected for signal reception by the modem. In one aspect, each antenna element of the array antenna can be coupled to one port of the Butler matrix, for example, via one or more low noise amplifiers (LNAs), power amplifiers (PAs), etc., to compensate for insertion loss. The phase adjusters in the Butler matrix may be active phase adjusters (requiring connection to a power source) or passive phase adjusters (not requiring connection to a power source). In one non-limiting aspect, for example, the phase adjusters in the Butler matrix may be implemented using delay lines.

[0042] In one aspect, the modem and / or another component of the wireless communication device can control the Butler matrix and / or other associated components (e.g., control the gain of an amplifier connecting an output port of the Butler matrix with an antenna element) to form a desired beam for transmitting RF signals and / or to receive RF signals via a desired beam. In one aspect, for example, the modem and / or another component of the wireless communication device can control the Butler matrix and / or other associated components to generate multiple signals that are phase-shifted versions of each other in order to generate a beam by transmitting such signals via multiple antenna elements of an array antenna.

[0043] In one non-limiting exemplary embodiment, a Butler matrix having N input ports and an equal number of N output ports can enable an array antenna to provide phase differences between adjacent antenna elements in an array antenna having N antenna elements, with each of the N input ports of the Butler matrix being associated with a different desired beam to be generated by the array antenna. In one embodiment, for example, the Butler matrix can be configured to generate N orthogonally spaced beams having the following planar angles:

[0044]

number

[0045] where λ is the wavelength equal to the reciprocal of the carrier frequency, d is the distance between adjacent antennas (which may be, for example, ∼=λ / 2), and k is: k = -N+1:2:N-1, Such a beam configuration is created by the following adjacent antenna phase differences:

[0046]

number

[0047] In one embodiment, for example,

[0048]

number

[0049] Hybrid couplers and

[0050]

number

[0051] Using fixed phase adjusters, a Butler matrix may be realized.

[0052] 3, in one non-limiting embodiment, a 4×4 Butler matrix 300 may be implemented to transmit a desired beam 316 via multiple antenna elements 312 of an array antenna 314. The 4×4 Butler matrix 300 is a Butler matrix having four input ports 308 and four output ports 310, with each output port 310 associated with one antenna element 312 in the array antenna 314. Although some of the embodiments are described herein with respect to transmitting a desired beam using a Butler matrix, the embodiments are not so limited and each embodiment may also be used to receive a desired beam. For example, although FIG. 3 is described herein with respect to transmitting a desired beam 316 using a 4×4 Butler matrix 300, the present aspect is not so limited, and the 4×4 Butler matrix 300 may also be used to receive a desired beam 316, in which case the 4×4 Butler matrix 300 receives a signal on an output port 310 and then generates a signal on one or more input ports 308.

[0053] The exemplary 4x4 Butler matrix 300 includes two 45° phase adjusters 302, four 3dB 90° hybrid couplers 304, and two crossovers 306. Each 45° phase adjuster 302 is a two-port circuit that receives a signal on one port and outputs a 45° phase-shifted version of that signal on the other port. Each 3dB 90° hybrid coupler 304 is a circuit with two input ports and two output ports. The 3dB 90° hybrid coupler 304 divides the power of an input signal received on the input port between two output signals generated on the two output ports and also induces a 90° phase shift between the two output signals generated on the two output ports. Each crossover 306 is a four-port circuit in which one conductor (connecting a first input port to a first output port) crosses another conductor (connecting a second input port to a second output port) with an air gap between them.

[0054] The 45° phase adjusters 302, 3 dB 90° hybrid couplers 304, and crossovers 306 are configured and arranged such that activation of an input port 308 of the 4×4 Butler matrix 300 activates all output ports 310 of the 4×4 Butler matrix 300, but with varying phase shifts relative to one another, such that the interaction of the RF transmissions of the antenna elements 312 fed by the output ports 314 creates a beam 316 corresponding to the activated input port 308. Table 1 provides example phases on each output port 310 of the exemplary 4×4 Butler matrix 300, given that one input port 308 is activated to create a beam 316.

[0055] [Table 1]

[0056] Thus, a Butler matrix can be implemented to provide a passive feed N×N network (N input ports and N output ports) with beam steering capability for an integrated array antenna (URA), where the N output ports of the Butler matrix are connected to respective antenna elements and the N input ports of the Butler matrix represent N orthogonal beam ports. Compared to using N phased arrays for beamforming, a Butler matrix can have lower power consumption, complexity, and / or cost. Furthermore, an N×N Butler matrix can be designed, replicated, concatenated, etc., to achieve a 3D Butler matrix connected to an N×N URA to create N×N orthogonal plane wave beams.

[0057] In one non-limiting embodiment, for example, each of n input ports and 2 n A Butler matrix with two output ports is n ×2 n 2 beams to create orthogonal plane waves n ×2 n 4, in one non-limiting exemplary embodiment, a 3D Butler matrix 400 having 16 input ports and 16 output ports can be configured to provide a passive feed to a 4x4 array antenna 402 having 16 antenna elements 403 arranged in four columns, with each column containing four antenna elements 403. That is, although the 4x4 antenna elements 403 are shown schematically in one column in FIG. 1, the array antenna 402 is 2D and includes a 4x4 matrix of antenna elements 403.

[0058] In this non-limiting exemplary embodiment, 3D Butler matrix 400 includes a first-layer 2D Butler matrix 404 having 16 input ports and 16 output ports, and a second-layer 2D Butler matrix 406 having 16 input ports and 16 output ports, with each of first-layer 2D Butler matrix 404 and second-layer 2D Butler matrix 406 including four 4×4 Butler matrices 408. In one non-limiting embodiment, each of the 4×4 Butler matrices 408 in first-layer 2D Butler matrix 404 or second-layer 2D Butler matrix 406 can be implemented similarly to 4×4 Butler matrix 300 described above with reference to FIG. 3 , e.g., using phase adjusters and hybrid couplers, such that activating an input port of each 4×4 Butler matrix 408 activates all output ports of that 4×4 Butler matrix 408.

[0059] In one aspect, the output ports of the first-layer 2D Butler matrix 404 are connected to the input ports of the second-layer 2D Butler matrix 406 such that the four output ports of each 4×4 Butler matrix 408 in the first-layer 2D Butler matrix 404 are connected to the four input ports of four different 4×4 Butler matrices 408 in the second-layer 2D Butler matrix 406. Thus, activating an output port of the first-layer 2D Butler matrix 404 activates one input port in each 4×4 Butler matrix 408 in the second-layer 2D Butler matrix 406, and therefore activates all output ports of the second-layer 2D Butler matrix 406. Thus, activating an output port of the first-layer 2D Butler matrix 404 activates all output ports of the second-layer 2D Butler matrix 406. Therefore, when an input port of the first layer 2D Butler matrix 404 is activated, all output ports of the second layer 2D Butler matrix 406 are activated, and as a result, all antenna elements 403 in the 4x4 array antenna 402 are activated.

[0060] Furthermore, assuming that the 4×4 Butler matrices 408 in first-layer 2D Butler matrix 404 are identical to each other and that the 4×4 Butler matrices 408 in second-layer 2D Butler matrix 406 are also identical to each other, the output ports of first-layer 2D Butler matrix 404 are connected to input ports of second-layer 2D Butler matrix 406, such that selecting a 4×4 Butler matrix 408 in first-layer 2D Butler matrix 404 selects the same input port of each of the 4×4 Butler matrices 408 in second-layer 2D Butler matrix 406. For example, in one embodiment, selecting a first 4x4 Butler matrix 408 in first-layer 2D Butler matrix 404 selects a first input port for each of the 4x4 Butler matrices 408 in second-layer 2D Butler matrix 406, while selecting a second 4x4 Butler matrix 408 in first-layer 2D Butler matrix 404 selects a second input port for each of the 4x4 Butler matrices 408 in second-layer 2D Butler matrix 406, and so on.

[0061] In one non-limiting aspect, different 4×4 Butler matrices 408 in the first-layer 2D Butler matrix 404 may be associated with different beam elevation angles, while different input ports of the 4×4 Butler matrix 408 in the first-layer 2D Butler matrix 404 may be associated with different beam azimuth angles. For example, four Butler matrices 408 in the first-layer 2D Butler matrix 404 may be associated with four different beam elevation angles, and four input ports of the 4×4 Butler matrix 408 in the first-layer 2D Butler matrix 404 may be associated with four different beam azimuth angles. For example, to achieve a beam having a desired azimuth angle and a desired elevation angle, an input port of the Butler matrix 408 in the first-layer 2D Butler matrix 404 is activated, the input port associated with the desired azimuth angle, and the Butler matrix 408 associated with the desired beam elevation angle.

[0062] However, the present embodiment is not so limited. For example, in an alternative embodiment, different 4×4 Butler matrices 408 in the first-layer 2D Butler matrix 404 may be associated with different beam azimuth angles, while different input ports of the 4×4 Butler matrix 408 in the first-layer 2D Butler matrix 404 may be associated with different beam elevation angles. In this case, to achieve a beam having a desired azimuth angle and a desired elevation angle, an input port of the Butler matrix 408 in the first-layer 2D Butler matrix 404 is activated, the input port being associated with the desired elevation angle, and the Butler matrix 408 being associated with the desired beam azimuth angle.

[0063] In one non-limiting embodiment, for example, activation of the 4x4 array antenna 402 in response to activation of each of the 16 input ports of the first layer 2D Butler matrix 404 provides a 2D pattern of beams 500 as in FIG. 5, each beam corresponding to the activation of one input port of the first layer 2D Butler matrix 404.

[0064] 4 is symmetric, the present embodiment is not so limited. For example, a 3D Butler matrix may be configured to feed an array antenna of size A×B, where A is different from B. For example, to feed an A×B array antenna, the 3D Butler matrix may include a second layer 2D Butler matrix having B A×A Butler matrices (B Butler matrices each having A input ports and A output ports).

[0065] 6, in one non-limiting embodiment, a 3D Butler matrix 600 having 16x4 output ports may be implemented to feed a 16x4 URA 602 (e.g., a URA having four columns of antenna elements 603 with 16 antenna elements 603 in each column). In one embodiment, for example, the 3D Butler matrix 600 may include a second-layer 2D Butler matrix 604 having four 16x16 Butler matrices 608 (four Butler matrices each having 16 input ports and 16 output ports) and a first-layer 2D Butler matrix 606 having sixteen 4x4 Butler matrices 610 (sixteen Butler matrices each having four input ports and four output ports). However, the embodiment is not so limited. For example, in yet another alternative embodiment, a 16x4 URA may be fed by a 3D Butler matrix that includes a first layer 2D Butler matrix having four 16x16 Butler matrices (four Butler matrices each with 16 input ports and 16 output ports) and a second layer 2D Butler matrix having sixteen 4x4 Butler matrices (sixteen Butler matrices each with four input ports and four output ports).

[0066] 7, in an alternative non-limiting exemplary embodiment, a first-to-second layer switch 710 can be used to implement a 3D Butler matrix 700 that provides the same beam steering functionality as 3D Butler matrix 400 (FIG. 4) while including fewer 4×4 Butler matrices 708 compared to 3D Butler matrix 400. That is, 3D Butler matrix 700 also has 16 output ports and generates the same output signals as 3D Butler matrix 400, resulting in 16 output ports providing passive feeds for 4×4 array antenna 702. Thus, due to the use of fewer 4×4 Butler matrices 708 compared to 3D Butler matrix 400, 3D Butler matrix 700 can provide the same beamforming functionality and the same beam angles as 3D Butler matrix 400, but at a reduced cost, size, and / or complexity than 3D Butler matrix 400.

[0067] In one non-limiting exemplary embodiment, 3D Butler matrix 700 includes a first-layer 2D Butler matrix 704 having four input ports and four output ports, and a second-layer 2D Butler matrix 706 having 16 input ports and 16 output ports. First-layer 2D Butler matrix 704 includes only one 4×4 Butler matrix 708, while second-layer 2D Butler matrix 706 includes four 4×4 Butler matrices 708. Again, each of the 4×4 Butler matrices 708 in 3D Butler matrix 700 can be implemented similarly to 4×4 Butler matrix 300 described above with reference to FIG. 3 (e.g., using phase adjusters and hybrid couplers) such that activating an input port of the 4×4 Butler matrix 708 activates all output ports of that 4×4 Butler matrix 708.

[0068] In one aspect, the first-second layer switches 710 are controllable via control signals 713 applied to control input pins 712 of the first-second layer switches 710 to selectively connect the output ports of the first layer 2D Butler matrices 704 to at least a subset of the input ports of the second layer 2D Butler matrices 706, such that at any given time, each output port of the 4×4 Butler matrices 708 in the first layer 2D Butler matrix 704 is connected to one selected input port in each 4×4 Butler matrix 708 in the second layer 2D Butler matrix 706. Thus, when an input port of the first layer 2D Butler matrix 704 is activated, all output ports of the second layer 2D Butler matrix 706 are activated, and as a result, all antenna elements 703 in the 4×4 array antenna 702 are activated.

[0069] In one aspect, assuming the 4×4 Butler matrices 708 in the second layer 2D Butler matrix 706 are identical to one another, the first layer-second layer switch 702 is controllable to select the same input port of each of the 4×4 Butler matrices 708 in the second layer 2D Butler matrix 706 as being connected to one of the four output ports of the first layer 2D Butler matrix 704. More specifically, for example, in one aspect, first-tier-second-tier switch 710 may be configured such that by applying a first signal value to control input 712 of first-tier-second-tier switch 710, a first input port of each of 4×4 Butler matrices 708 in second-tier 2D Butler matrix 706 is selected for connection to a respective output port of first-tier 2D Butler matrix 704, while by applying a second signal value to control input 712 of first-tier-second-tier switch 710, a second input port of each of 4×4 Butler matrices 708 in second-tier 2D Butler matrix 706 is selected for connection to a respective output port of first-tier 2D Butler matrix 704, and so on.

[0070] More specifically, for example, in one aspect, first layer-second layer switch 710 may be configured such that by applying a first signal value to a control input 712 of first layer-second layer switch 710, a first output port, a second output port, a third output port, and a fourth output port of first layer 2D Butler matrix 704 are connected to first input ports of a first Butler matrix, a second Butler matrix, a third Butler matrix, and a fourth Butler matrix 708 in second layer 2D Butler matrix 706, respectively. Also, by applying a second signal value to the control input 712 of the first layer-second layer switch 710, the first output port, the second output port, the third output port, and the fourth output port of the first layer 2D Butler matrix 704 are connected to second input ports of the first Butler matrix, the second Butler matrix, the third Butler matrix, and the fourth Butler matrix 708 in the second layer 2D Butler matrix 706, respectively, and so on.

[0071] More specifically, applying a first signal value to a control input 712 of first layer-second layer switch 710 causes first layer-second layer switch 710 to connect a first output port of first layer 2D Butler matrix 704 to a first input port of a first 4×4 Butler matrix 708 in second layer 2D Butler matrix 706, connect a second output port of first layer 2D Butler matrix 704 to a first input port of a second 4×4 Butler matrix 708 in second layer 2D Butler matrix 706, and so on. Also, for example, applying a second signal value to the control input 708 of the first layer-second layer switch 708 causes the first layer-second layer switch 708 to connect a first output port of the first layer 2D Butler matrix 704 to a second input port of a first 4×4 Butler matrix 708 in the second layer 2D Butler matrix 706, connect a second output port of the first layer 2D Butler matrix 704 to a second input port of a second 4×4 Butler matrix 708 in the second layer 2D Butler matrix 706, and so on.

[0072] In one non-limiting aspect, different signal values ​​applied to the control input 712 of the first-tier-second-tier switch 710 may be associated with different beam elevation angles, while different input ports of the 4×4 Butler matrix 708 in the first-tier 2D Butler matrix 704 may be associated with different beam azimuth angles. For example, four different signal values ​​applied to the control input 712 of the first-tier-second-tier switch 710 may be associated with four different beam elevation angles, and four input ports of the 4×4 Butler matrix 708 in the first-tier 2D Butler matrix 704 may be associated with four different beam azimuth angles. For example, to achieve a beam having a desired azimuth angle and a desired elevation angle, an input port of the Butler matrix 708 in the first-tier 2D Butler matrix 704 is activated, the input port associated with the desired azimuth angle, and a signal value associated with the desired beam elevation angle is applied to the control input 712 of the first-tier-second-tier switch 710.

[0073] However, the present embodiment is not so limited. For example, in an alternative embodiment, different signal values ​​applied to the control input 712 of the first-tier-second-tier switch 710 may be associated with different beam azimuth angles, while different input ports of the 4×4 Butler matrix 708 in the first-tier 2D Butler matrix 704 may be associated with different beam elevation angles. For example, four different signal values ​​applied to the control input 712 of the first-tier-second-tier switch 710 may be associated with four different beam azimuth angles, and four input ports of the 4×4 Butler matrix 708 in the first-tier 2D Butler matrix 704 may be associated with four different beam elevation angles. For example, to achieve a beam having a desired azimuth angle and a desired elevation angle, an input port of Butler matrix 708 in first layer 2D Butler matrix 704 is activated, which input port is associated with the desired elevation angle, and a signal value associated with the desired beam azimuth angle is applied to a control input 712 of first layer-second layer switch 710.

[0074] By using the layer 1-layer 2 switch 710, the 3D Butler matrix 700 can provide the same beamforming functionality as the 3D Butler matrix 400 (FIG. 4), but with a smaller total number of 4×4 Butler matrices 708, which can reduce cost, size, and / or complexity, for example, in high-dimensional multi-antenna communications.

[0075] In one embodiment, the 3D Butler matrix 700 can be used to support multiple links, for example, by activating two or more input ports of the first-layer 2D Butler matrix 704 corresponding to multiple different azimuth angles. Multiple links can correspond to multiple beams in one dimension (azimuth or elevation) to avoid undesired beams. For example, in one exemplary embodiment, two links can be used by activating two input ports of a 4×4 Butler matrix 708 in the first-layer 2D Butler matrix 704, where the two input ports are associated with two different azimuth angles. Alternatively, in some embodiments, the first-layer 2D Butler matrix 704 may include two 4×4 Butler matrices, each supporting one stream. In this case, the 3D Butler matrix 700 can be used to support two links by activating one input port of each of the two 4×4 Butler matrices 708 in the first-layer 2D Butler matrix 704.

[0076] In one aspect, the layer 1-layer 2 switch 710 maintains reciprocity so that the 3D Butler matrix 700 can support both uplink and downlink communications.

[0077] 7, the first-second layer switch 710 is used to reduce the number of 4×4 Butler matrices 708 in the 3D Butler matrix 700 compared to the 3D Butler matrix 400 of FIG. 4, but the embodiment is not so limited. For example, with reference to FIG. 8, in another non-limiting embodiment, a first-second layer switch 812 having four inputs and 16×4 outputs may be configurable via a control signal applied to a control input pin 814 to realize a 3D Butler matrix 800 that has only one 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806 but can otherwise provide the same beam output as the 3D Butler matrix 600 of FIG. 6. Specifically, a 16×4 URA 802 having four columns each containing 16 antenna elements 803 may be fed by an output port of the second layer 2D Butler matrix 804 of the 3D Butler matrix 800. Similar to 3D Butler matrix 600 of Figure 6, second layer 2D Butler matrix 804 of 3D Butler matrix 800 includes four 16x16 Butler matrices 808 (four Butler matrices each with 16 input ports and 16 output ports). However, by using a first-to-second layer switch 812, 3D Butler matrix 800 can provide the same beamforming functionality as 3D Butler matrix 600 (Figure 6), except that there is only one 4x4 Butler matrix 810 in first layer 2D Butler matrix 806, which can reduce cost, size, and / or complexity.

[0078] In one aspect, the first-second layer switches 812 are controllable to selectively connect output ports of the first layer 2D Butler matrix 806 to at least a subset of input ports of the second layer 2D Butler matrix 804 via control signals 815 applied to control input pins 814 of the first-second layer switches 812. In one non-limiting aspect, for example, different signal values ​​applied to the control input pins 814 of the first-second layer switches 812 may be associated with different beam elevation angles, while different input ports of the 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806 may be associated with different beam azimuth angles. For example, 16 different signal values ​​may be applied to the control inputs 814 of the first-second layer switches 812 to select 16 different beam elevation angles, and four input ports of the 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806 may be associated with four different beam azimuth angles. For example, to achieve a beam having a desired azimuth angle and a desired elevation angle, an input port of Butler matrix 810 in first layer 2D Butler matrix 806 is activated, which input port is associated with the desired azimuth angle, and a signal value associated with the desired beam elevation angle is applied to control input pin 814 of first layer-second layer switch 812.

[0079] However, the present embodiment is not so limited. For example, in an alternative embodiment, different signal values ​​applied to the control input pin 814 of the first layer-second layer switch 812 may be associated with different beam azimuth angles, while different input ports of the 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806 may be associated with different beam elevation angles. For example, 16 different signal values ​​may be applied to the control input 814 of the first layer-second layer switch 812 to select 16 different beam azimuth angles, and four input ports of the 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806 may be associated with four different beam elevation angles. For example, to achieve a beam having a desired azimuth angle and a desired elevation angle, an input port of Butler matrix 810 in first layer 2D Butler matrix 806 is activated, which input port is associated with the desired elevation angle, and a signal value associated with the desired beam azimuth angle is applied to control input 814 of first layer-second layer switch 708.

[0080] In one non-limiting embodiment, in response to activation of an input port of a 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806, four inputs of the first layer-to-second layer switch 812 are activated and only four of the 16×4 outputs of the first layer-to-second layer switch 812 are activated (enabled).

[0081] In one non-limiting embodiment, first layer-second layer switches 812 may be implemented using four 1×16 switches, each having one input and 16 outputs, and controllable (via a control signal 815 applied to a control input pin 814 of first layer-second layer switches 812) to connect the input to one of the 16 outputs. In one embodiment, each of the 1×16 switches is associated with one of the output ports of the 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806 and one of the 16×16 Butler matrix 808 in the second layer 2D Butler matrix 804. More specifically, each input of the 1×16 switch is connected to one of the output ports of a 4×4 Butler matrix 810 in the first layer 2D Butler matrix 806, and the 16 outputs of each of the 1×16 switches are connected to 16 input ports of one of a 16×16 Butler matrix 808 in the second layer 2D Butler matrix 804.

[0082] In one non-limiting embodiment, for example, each 1×4 switch is controllable (via a control signal 815 applied to a control input pin 814 of a first-second layer switch 812) to select one input port of a 16×16 Butler matrix 808 in a second-tier 2D Butler matrix 804, where the selected input port of the 16×16 Butler matrix 808 in the second-tier 2D Butler matrix 804 corresponds to the desired beam azimuth or elevation angle. In this embodiment, when the four inputs of the first-second layer switch 812 are activated, only one output of each 1×16 switch is activated, and thus only four of the 16×4 outputs of the first-second layer switch 812 are activated (enabled). Furthermore, the four activated outputs of the first-second layer switch 812 are connected to the same number of input ports in the 16×16 Butler matrix 808 in the second-tier 2D Butler matrix 804. That is, when the four inputs of the first layer-second layer switch 812 are activated, the same number of input ports in each of the 16×16 Butler matrices 808 in the second layer 2D Butler matrix 804 are activated to select, for example, the desired beam azimuth or elevation angle.

[0083] In one aspect, to support two or more stream links, first layer 2D Butler matrix 806 may include two or more Butler matrices, with each Butler matrix supporting one stream / link. For example, in one non-limiting alternative aspect, first layer 2D Butler matrix 806 may include two Butler matrices of size 4×4, in which case first layer-to-second layer switch 812 would have eight inputs and 16×4 outputs of the first layer-to-second layer switch, with only eight of the 16×4 outputs being activated (enabled) at any given time.

[0084] In yet another alternative aspect, a 3D Butler matrix operable to feed a 16×4 URA can include a first layer 2D Butler matrix having one 16×16 Butler matrix (a Butler matrix having 16 input ports and 16 output ports), a second layer 2D Butler matrix having sixteen 4×4 Butler matrices (sixteen Butler matrices each having four input ports and four output ports), and a first layer-second layer switch having 16 inputs and 16×4 outputs and configurable to selectively connect the output ports of the first layer 2D Butler matrix to the input ports of the second layer 2D Butler matrix via control signals applied to control input pins. In one non-limiting aspect, for example, four different signal values ​​applied to the control input pin of the first-tier-second-tier switch 812 may be associated with four different beam elevation angles, while 16 input ports of a 16×16 Butler matrix in the first-tier 2D Butler matrix may be associated with different beam azimuth angles. In an alternative non-limiting aspect, for example, four different signal values ​​applied to the control input of the first-tier-second-tier switch 812 may be associated with four different beam azimuth angles, while 16 input ports of a 16×16 Butler matrix in the first-tier 2D Butler matrix may be associated with different beam elevation angles.

[0085] In one non-limiting embodiment, in response to activation of an input port of a 16×16 Butler matrix in the first layer 2D Butler matrix, 16 inputs of the first layer-second layer switch are activated and only 16 of the 16×4 outputs of the first layer-second layer switch are activated (enabled).

[0086] In one non-limiting embodiment, the first-second layer switches may be implemented using sixteen 1×4 switches, each having one input and four outputs and controllable (via a control signal applied to a control input pin of the first-second layer switch) to connect the input to one of the four outputs. In one embodiment, each of the 1×4 switches is associated with one of the output ports of the 16×16 Butler matrix in the first layer 2D Butler matrix and one of the 4×4 Butler matrices in the second layer 2D Butler matrix. More specifically, the input of each of the 1×4 switches is connected to one of the output ports of the 16×16 Butler matrix in the first layer 2D Butler matrix, and the four outputs of each of the 1×4 switches are connected to four input ports of one of the 4×4 Butler matrices in the second layer 2D Butler matrix.

[0087] In one non-limiting embodiment, for example, each 1×16 switch is controllable (via a control signal applied to a control input pin of the first-second layer switch) to select one input port of a 4×4 Butler matrix in the second-layer 2D Butler matrix, where the selected input port of the 4×4 Butler matrix in the second-layer 2D Butler matrix corresponds to the desired beam azimuth or elevation angle. In this embodiment, when the 16 inputs of the first-second layer switch are activated, only one output of each 1×4 switch is activated, and therefore only 16 of the 16×4 outputs of the first-second layer switch are activated (enabled). Furthermore, the 16 activated outputs of the first-second layer switch are connected to the same number of input ports in the 4×4 Butler matrix in the second-layer 2D Butler matrix. That is, when the 16 inputs of the first-second layer switch are activated, the same number of input ports in each of the 4x4 Butler matrices in the second layer 2D Butler matrix are activated to select, for example, the desired beam azimuth or elevation angle.

[0088] Although the number of input ports and output ports of each Butler matrix in the above embodiments is equal to one another and equal to a power of two (e.g., 4 input ports and 4 output ports, 16 input ports and 16 output ports, etc.), the embodiments are not so limited. For example, in some alternative embodiments, a 3D Butler matrix may include Butler matrices each having N input ports and M output ports, where N and M are not equal to one another, or where N and / or M are not powers of two to one another.

[0089] In one non-limiting embodiment, for example, a 3D Butler matrix may be configured for passive feeding of an N×N array antenna having N columns, each including N antenna elements. The 3D Butler matrix may include a first-layer 2D Butler matrix having N M×M Butler matrices (N>M≧1), a first-layer-second-layer switch that selectively connects the N×M inputs to the N×N outputs, and a second-layer 2D Butler matrix having N N×N Butler matrices. Thus, the 3D Butler matrix can enable N×M different beams with N×M different combinations of azimuth and elevation angles (e.g., N different azimuth angles×M different elevation angles, or M different azimuth angles×N different elevation angles). In one embodiment, beam activation information for controlling the input-output connections of the first-layer-second-layer switches can be inserted into the first-layer-second-layer switches (by control signals applied to control input pins of the first-layer-second-layer switches). In one non-limiting embodiment, for example, a desired beam is selected from one of N×M different beams, with each different input value to the control input pin of the first layer-second layer switch selecting a different elevation angle, and each input port of the first layer 2D Butler matrix selecting a different azimuth angle.

[0090] In yet another non-limiting aspect, for example, a 3D Butler matrix may include a first-tier 2D Butler matrix having N M×P Butler matrices, first-tier-second-tier switches that selectively connect the N×P input pins to N×P×Q output pins based on control signals applied to control input pins of the first-tier-second-tier switches, and a second-tier 2D Butler matrix having N×P Q×T Butler matrices, where N, M, P, Q, and T are positive integer values. Thus, the 3D Butler matrix can enable N×M×Q different beams with N×M×Q different combinations of azimuth and elevation angles.

[0091] 9 shows a flowchart of an example method 900 for multi-antenna wireless communication. In one aspect, for example, a UE 104 may perform the functions described in method 900 using one or more of the components described in FIG. 1 above or in FIGS. 10 and 11 below (e.g., modem 140, 3D Butler matrix 145, array antenna 144, RF front end 1088, transceiver 1002, processor 1012, and / or memory 1016). In another aspect, a base station 102 may perform the functions described in method 900 using one or more of the components described in FIG. 1 above or in FIGS. 11 and 12 below (e.g., modem 140, 3D Butler matrix 145, array antenna 144, RF front end 1288, transceiver 1202, processor 1212, and / or memory 1216).

[0092] At 902, method 900 includes selecting one or more input ports of a first-tier 2D Butler matrix for communication of one or more streams via one or more beams with an array antenna. For example, in one aspect, the UE 104, modem 140, 3D Butler matrix 145, array antenna 144, RF front end 1088, transceiver 1002, processor 1012, and / or memory 1016 may select one or more input ports of the first-tier 2D Butler matrix for communication of one or more streams via one or more beams with an array antenna. Thus, in one aspect, the UE 104, modem 140, 3D Butler matrix 145, array antenna 144, RF front end 1088, transceiver 1002, processor 1012, and / or memory 1016 may provide means for selecting one or more input ports of the first-tier 2D Butler matrix for communication of one or more streams via one or more beams with an array antenna. In another aspect, the base station 102, the modem 140, the 3D Butler matrix 145, the array antenna 144, the RF front end 1288, the transceiver 1202, the processor 1212, and / or the memory 1216 may select one or more input ports of the first-tier 2D Butler matrix for communication of one or more streams via one or more beams with the array antenna. Thus, in one aspect, the base station 102, the modem 140, the 3D Butler matrix 145, the array antenna 144, the RF front end 1288, the transceiver 1202, the processor 1212, and / or the memory 1216 may provide means for selecting one or more input ports of the first-tier 2D Butler matrix for communication of one or more streams via one or more beams with the array antenna.

[0093] 1 and 7, in one aspect, a modem 140 of a UE 104 or a base station 102 may select one or more input ports of a first-tier 2D Butler matrix 704 for communication of one or more streams via one or more beams by an array antenna 702. For example, the modem 140 may select input ports associated with desired beam elevation and azimuth angles such that applying one or more streams to the input ports associated with the desired beam elevation and azimuth angles generates phase-shifted versions of the streams on output ports of the second-tier 2D Butler matrix 706, and transmits one or more signals by antenna elements 703 of the array antenna 702 via beams having the desired azimuth or elevation angles.

[0094] At 904, the method 900 includes applying a control signal to a control input pin of a first-to-second layer switch, the first-to-second layer switch being configurable to selectively connect the first layer output ports of the first layer 2D Butler matrix to at least a subset of the second layer input ports of the second layer 2D Butler matrix based on the control signal. For example, in one aspect, the UE 104, the modem 140, the 3D Butler matrix 145, the array antenna 144, the RF front end 1088, the transceiver 1002, the processor 1012, and / or the memory 1016 may apply the control signal to a control input pin of the first-to-second layer switch, the first-to-second layer switch being configurable to selectively connect the first layer output ports of the first layer 2D Butler matrix to at least a subset of the second layer input ports of the second layer 2D Butler matrix based on the control signal. Thus, in one aspect, the UE 104, modem 140, 3D Butler matrix 145, array antenna 144, RF front end 1088, transceiver 1002, processor 1012, and / or memory 1016 may provide means for applying control signals to control input pins of the first layer-second layer switches, which are configurable to selectively connect first layer output ports of the first layer 2D Butler matrix to at least a subset of second layer input ports of the second layer 2D Butler matrix based on the control signals. In another aspect, the base station 102, the modem 140, the 3D Butler matrix 145, the array antenna 144, the RF front end 1288, the transceiver 1202, the processor 1212, and / or the memory 1216 may apply control signals to control input pins of the first-layer-second-layer switch, which is configurable to selectively connect the first layer output ports of the first layer 2D Butler matrix to at least a subset of the second layer input ports of the second layer 2D Butler matrix based on the control signals.Thus, in one aspect, the base station 102, modem 140, 3D Butler matrix 145, array antenna 144, RF front end 1288, transceiver 1202, processor 1212, and / or memory 1216 can provide means for applying control signals to control input pins of the first layer-second layer switches, which are configurable to selectively connect first layer output ports of the first layer 2D Butler matrix to at least a subset of second layer input ports of the second layer 2D Butler matrix based on the control signals.

[0095] For example, in one aspect, referring to FIGS. 1 and 7, the modem 140 of the UE 104 or base station 102 may apply control signals 713 to control input pins 712 of the first-second layer switch 710 such that the first-second layer switch 710 selectively connects output ports of the first-second layer 2D Butler matrix 704 to at least a subset of input ports of the second-second layer 2D Butler matrix 706 to generate beams having desired azimuth or elevation angles in response to streams applied to the input ports of the first-second layer 2D Butler matrix 704. For example, the modem 140 of the UE 104 or base station 102 may apply one or more streams to input ports of the first layer 2D Butler matrix 704, which generates phase-shifted versions of the streams on output ports of the second layer 2D Butler matrix 706, and apply control signals 712 associated with desired beam elevation and azimuth angles to control the connection of the first layer-second layer switch 710 such that one or more signals are transmitted by the antenna elements 703 of the array antenna 702 through beams having the desired azimuth or elevation angles.

[0096] At 906, the method 900 further includes transmitting or receiving the one or more streams via one or more beams with an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-layer 2D Butler matrix. For example, in one aspect, the UE 104, the modem 140, the 3D Butler matrix 145, the array antenna 144, the RF front end 1088, the transceiver 1002, the processor 1012, and / or the memory 1016 may transmit or receive the one or more streams via one or more beams with an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-layer 2D Butler matrix. Thus, in one aspect, the UE 104, the modem 140, the 3D Butler matrix 145, the array antenna 144, the RF front end 1088, the transceiver 1002, the processor 1012, and / or the memory 1016 may provide means for transmitting or receiving one or more streams via one or more beams by an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-layer 2D Butler matrix. In another aspect, the base station 102, the modem 140, the 3D Butler matrix 145, the array antenna 144, the RF front end 1288, the transceiver 1202, the processor 1212, and / or the memory 1216 may transmit or receive one or more streams via one or more beams by an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-layer 2D Butler matrix.Thus, in one aspect, the base station 102, modem 140, 3D Butler matrix 145, array antenna 144, RF front end 1288, transceiver 1202, processor 1212, and / or memory 1216 can provide means for transmitting or receiving one or more streams via one or more beams by an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second layer 2D Butler matrix.

[0097] For example, in one aspect, referring to Figures 1 and 7, a UE 104 or a base station 102 may transmit or receive one or more streams via one or more beams by an array antenna 702, the array antenna 702 including a plurality of antenna elements 703, each of the plurality of antenna elements 703 being associated with one output port of a second layer 2D Butler matrix 706.

[0098] For example, in one non-limiting exemplary embodiment, to transmit a stream via a beam having a desired azimuth angle and a desired elevation angle, modem 140 can select an input port of first-tier Butler matrix 704, the input port being associated with the desired beam azimuth angle. Modem 140 can also apply a control signal 713 to a control input pin 712 of first-tier-second-tier switch 710, the control signal 713 being associated with the desired beam elevation angle. By selecting an input port associated with the desired beam azimuth angle and selecting a control signal 713 associated with the beam elevation angle, 3D Butler matrix 700 generates signals on an output port of second-tier Butler matrix 706 that have a relative phase shift with respect to each other and cause array antenna 702 to generate a beam having the desired azimuth angle and elevation angle. 3D Butler matrix 700 also provides a reciprocity function. That is, the same selection made by modem 140 to transmit a stream via a beam having a desired azimuth angle and a desired elevation angle also causes 3D Butler matrix 700 to operate in a receive mode to receive a stream via a beam having a desired azimuth angle and a desired elevation angle.

[0099] 10 , an example implementation of a UE 104 may include various components, some of which have already been described above and will be further described herein, including components such as one or more processors 1012 and memories 1016 and a transceiver 1002 communicating via one or more buses 1044, which may operate in conjunction with a modem 140, an array antenna 144, and / or a 3D Butler matrix 145 to enable one or more of the functions described herein related to beamforming in multi-antenna wireless communications. In FIG. 10 , the 3D Butler matrix 145 is configured and arranged to couple the array antenna 144 with an RF front end 1088 of the UE 104, although the present embodiment is not so limited. For example, in an alternative embodiment, the 3D Butler matrix 145 may be configured and arranged to couple the RF front end 1088 with the transceiver 1002.

[0100] In one aspect, the one or more processors 1012 can include the modem 140 and / or be part of the modem 140 using one or more modem processors. Thus, various functions described herein with reference to beamforming may be included in the modem 140 and / or the processor 1012, and in some aspects may be performed by a single processor, while in other aspects different ones of the functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 1012 may include any one of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with the transceiver 1002, or any combination thereof. In other aspects, some of the features of the one or more processors 1012 and / or the modem 140 described herein with reference to beamforming may be performed by the transceiver 1002.

[0101] The memory 1016 may also be configured to store data as used herein and / or local versions of the applications 1075 executed by the at least one processor 1012. The memory 1016 may include any type of computer-readable medium usable by a computer or the at least one processor 1012, such as random access memory (RAM), read-only memory (ROM), tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, the memory 1016 may be a non-transitory computer-readable storage medium storing one or more computer-executable codes and / or data associated therewith when the UE 104 operates the at least one processor 1012 to perform the beamforming functions described herein.

[0102] The transceiver 1002 may include at least one receiver 1006 and at least one transmitter 1008. The receiver 1006 may include hardware, firmware, and / or software code executable by a processor to receive data, where the code comprises instructions and is stored in a memory (e.g., a computer-readable medium). The receiver 1006 may be, for example, a radio frequency (RF) receiver. In an aspect, the receiver 1006 may receive signals transmitted by at least one base station 102. Additionally, the receiver 1006 may process such received signals and obtain signal measurements such as, but not limited to, Ec / Io, signal-to-noise ratio (SNR), reference signal received power (RSRP), received signal strength indicator (RSSI), etc. The transmitter 1008 may include hardware, firmware, and / or software code executable by a processor to transmit data, where the code comprises instructions and is stored in a memory (e.g., a computer-readable medium). Suitable examples of the transmitter 1008 may include, but are not limited to, an RF transmitter.

[0103] Moreover, in one aspect, the UE 104 may include an RF front end 1088 that may be in operative communication with the 3D Butler matrix 145, one or more antennas 144, and a transceiver 1002 for receiving and transmitting radio transmissions, e.g., wireless communications transmitted by at least one base station 102 or wireless transmissions transmitted by the UE 104. The RF front end 1088 may be connected to the one or more antennas 144 via the 3D Butler matrix 145 and may include one or more low noise amplifiers (LNAs) 1090, one or more switches 1092, one or more power amplifiers (PAs) 1098, and one or more filters 1096 for transmitting and receiving RF signals.

[0104] In one aspect, the LNAs 1090 can amplify the received signal at a desired power level. In one aspect, each LNA 1090 can have a specified minimum and maximum gain value. In one aspect, the RF front end 1088 can use one or more switches 1092 to select a particular LNA 1090 and its specified gain value based on the desired gain value of a particular application.

[0105] Further, for example, one or more PAs 1098 may be used by the RF front end 1088 to amplify the RF output signal at a desired output power level. In one aspect, each PA 1098 may have a specified minimum and maximum gain value. In one aspect, the RF front end 1088 may use one or more switches 1092 to select a particular PA 1098 and its specified gain value based on the desired gain value of a particular application.

[0106] Also, one or more filters 1096 may be used by the RF front end 1088, for example, to filter a received signal to obtain an input RF signal. Similarly, in an aspect, each filter 1096 may be used to filter an output from a respective PA 1098, for example, to generate an output signal for transmission. In an aspect, each filter 1096 may be connected to a particular LNA 1090 and / or PA 1098. In an aspect, the RF front end 1088 may use one or more switches 1092 to select a transmit path or a receive path using a specified filter 1096, LNA 1090, and / or PA 1098 based on a configuration specified by the transceiver 1002 and / or processor 1012.

[0107] Thus, the transceiver 1002 may be configured to transmit and receive wireless signals through one or more antennas 144 via the 3D Butler matrix 145 and the RF front end 1088. In one aspect, the transceiver 1002 may be tuned to operate at a designated frequency so that the UE 104 can communicate with, for example, one or more base stations 102, or one or more cells associated with one or more base stations 102. In one aspect, for example, the modem 140 may configure the transceiver 1002 to operate at a designated frequency and power level based on the UE configuration of the UE 104 and the communication protocol used by the modem 140.

[0108] In one aspect, the modem 140 may be a multi-band multi-mode modem that can process digital data and communicate with the transceiver 1002 so that the digital data is sent and received using the transceiver 1002. In one aspect, the modem 140 may be multi-band and configured to support multiple frequency bands for a particular communication protocol. In one aspect, the modem 140 may be multi-mode and configured to support multiple operating networks and communication protocols. In an aspect, the modem 140 can control one or more components of the UE 104 (e.g., the RF front end 1088, the transceiver 1002, the 3D Butler matrix 145) to enable transmission and / or reception of signals from the network based on a specified modem configuration. In an aspect, the modem configuration may be based on the modem mode and the frequency band in use. In another aspect, the modem configuration may be based on UE configuration information associated with the UE 104, such as provided by the network during cell selection and / or cell reselection.

[0109] In an aspect, the processor 1012 may correspond to one or more of the processors described below with respect to the UE 1150 of FIG. 11. Similarly, the memory 1016 may correspond to the memory described below with respect to the UE 1150 of FIG.

[0110] In one configuration, the UE 104 or UE 1150 may be an apparatus for multi-antenna wireless communication, including means for implementing any of the appended claims for multi-antenna wireless communication by a UE. The means may be one or more of the above-mentioned components of the UE 104 and / or the processor 1012 of the UE 104 configured to perform the functions recited by the means. As explained above, the processor 1012 may include the TX processor 1168, the RX processor 1156, and the controller / processor 1159 of the UE 1150, which will be described below with reference to FIG. 11 . Thus, in one configuration, the means may be the TX processor 1168, the RX processor 1156, and the controller / processor 1159 configured to perform the functions recited by the means.

[0111] 11 is a block diagram of a base station 1110 in communication with a UE 1150 in an access network, where the base station 1110 may be an exemplary implementation of a base station 102 and the UE 1150 may be an exemplary implementation of a UE 104. Although not shown in FIG. 11 , in some aspects the base station 1110 may include a 3D Butler matrix and / or an RF front end configured and arranged to couple multiple antennas 1120 of the base station 1110 with a transceiver 1118 of the base station 1110, as described herein with reference to various aspects. Similarly, although not shown in FIG. 11 , in some aspects the UE 1150 may include a 3D Butler matrix and / or an RF front end configured and arranged to couple multiple antennas 1152 of the UE 1150 with a transceiver 1154 of the UE 1150, as described herein with reference to various aspects.

[0112] In the DL, IP packets from the EPC 160 may be provided to the controller / processor 1175. The controller / processor 1175 performs Layer 3 and Layer 2 functions. Layer 3 includes the Radio Resource Control (RRC) layer, and Layer 2 includes the Service Data Adaptation Protocol (SDAP) layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, and the Medium Access Control (MAC) layer. The controller / processor 1175 performs RRC layer functions related to broadcasting system information (e.g., MIBs, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-Radio Access Technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions related to header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functions related to forwarding upper layer packet data units (PDUs), error correction via ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and mapping between logical channels and transport channels, multiplexing MAC SDUs onto transport blocks (TBs), and MAC SDUs from TBs. It provides MAC layer functions related to demultiplexing of SDUs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0113] The transmit (TX) processor 1116 and receive (RX) processor 1170 implement Layer 1 functionality associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on transport channels, forward error correction (FEC) coding / decoding of transport channels, interleaving, rate matching, mapping onto physical channels, modulation / demodulation of physical channels, and MIMO antenna processing. The TX processor 1116 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-ary quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be separated into parallel streams. Each stream may then be mapped to OFDM subcarriers, multiplexed with a reference signal (e.g., a pilot) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time-domain OFDM symbol stream. The OFDM streams are spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator 1174 may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback transmitted by the UE 1150. Each spatial stream may then be provided to a different antenna 1120 via a separate transmitter 1118TX. Each transmitter 1118TX may modulate an RF carrier with the respective spatial stream for transmission.

[0114] At the UE 1150, each receiver 1154RX receives a signal through its respective antenna 1152. Each receiver 1154RX recovers information modulated onto an RF carrier and provides the information to a receive (RX) processor 1156. The TX processor 1168 and the RX processor 1156 implement Layer 1 functions associated with various signal processing functions. The RX processor 1156 may perform spatial processing on the information to recover any spatial streams destined for the UE 1150. Multiple spatial streams may be combined into a single OFDM symbol stream by the RX processor 1156 when destined for the UE 1150. The RX processor 1156 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency-domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the signal constellation point that was most likely transmitted by the base station 1110. These soft decisions may be based on channel estimates calculated by a channel estimator 1158. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted by the base station 1110 on the physical channel. The data and control signals are then provided to a controller / processor 1159, which implements Layer 3 and Layer 2 functions.

[0115] The controller / processor 1159 may be associated with a memory 1160 that stores program codes and data. The memory 1160 may be referred to as a computer-readable medium. In the UL, the controller / processor 1159 performs demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 1159 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0116] Similar to the functions described with respect to DL transmission by base station 1110, controller / processor 1159 provides RRC layer functions related to system information (e.g., MIB, SIB) collection, RRC connection, and measurement reporting; PDCP layer functions related to header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions related to transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions related to mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0117] Channel estimates derived by the channel estimator 1158 from a reference signal or feedback transmitted by the base station 1110 may be used by the TX processor 1168 to select an appropriate coding and modulation scheme and to facilitate spatial processing. The spatial streams generated by the TX processor 1168 may be provided to different antennas 1152 via separate transmitters 1154TX. Each transmitter 1154TX may modulate an RF carrier with a respective spatial stream for transmission.

[0118] The UL transmission is processed at the base station 1110 in a manner similar to that described for the receiver function at the UE 1150. Each receiver 1118RX receives a signal through its respective antenna 1120. Each receiver 1118RX recovers the information modulated onto the RF carrier and provides the information to an RX processor 1170.

[0119] The controller / processor 1175 may be associated with a memory 1176 that stores program codes and data. The memory 1176 may be referred to as a computer-readable medium. In the UL, the controller / processor 1175 performs demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the UE 1150. The IP packets from the controller / processor 1175 may be provided to the EPC 160. The controller / processor 1175 is also responsible for error detection to support HARQ operations using an ACK and / or NACK protocol.

[0120] At least one of the TX processor 1168, the RX processor 1156, and the controller / processor 1159 may be configured to implement aspects related to beamforming in multi-antenna wireless communication of FIG.

[0121] At least one of the TX processor 1116, the RX processor 1170, and the controller / processor 1175 may be configured to implement aspects related to beamforming in multi-antenna wireless communication of FIG.

[0122] 12 , an example implementation of a base station 102 may include various components, some of which have already been described above and will be further described herein, including components such as one or more processors 1212 and memories 1216 and transceivers 1202 communicating via one or more buses 1244, which may operate in conjunction with a modem 140, an array antenna 144, and / or a 3D Butler matrix 145 to enable one or more of the functions described herein related to beamforming in multi-antenna wireless communications. In FIG. 12 , the 3D Butler matrix 145 is configured and arranged to couple the array antenna 144 with an RF front end 1288 of the base station 102, although the embodiment is not so limited. For example, in an alternative embodiment, the 3D Butler matrix 145 may be configured and arranged to couple the RF front end 1288 with the transceiver 1202.

[0123] In one aspect, the one or more processors 1212 can include the modem 140 and / or be part of the modem 140 using one or more modem processors. Thus, various functions described herein with reference to beamforming may be included in the modem 140 and / or the processor 1212, and in some aspects may be performed by a single processor, while in other aspects different ones of the functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 1212 may include any one of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with the transceiver 1202, or any combination thereof. In other aspects, some of the features of the one or more processors 1212 and / or the modem 140 described herein with reference to beamforming may be performed by the transceiver 1202.

[0124] The memory 1216 may also be configured to store data as used herein and / or local versions of the applications 1275 executed by the at least one processor 1212. The memory 1216 may include any type of computer-readable medium usable by a computer or the at least one processor 1212, such as random access memory (RAM), read-only memory (ROM), tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, the memory 1216 may be a non-transitory computer-readable storage medium storing one or more computer-executable codes and / or data associated therewith when the base station 102 operates the at least one processor 1212 to perform the beamforming functions described herein.

[0125] The transceiver 1202 may include at least one receiver 1206 and at least one transmitter 1208. The receiver 1206 may include hardware, firmware, and / or software code executable by a processor to receive data, where the code comprises instructions and is stored in a memory (e.g., a computer-readable medium). The receiver 1206 may be, for example, a radio frequency (RF) receiver. In one aspect, the receiver 1206 may receive signals transmitted by the at least one UE 104. Additionally, the receiver 1206 may process such received signals and obtain signal measurements such as, but not limited to, Ec / Io, signal-to-noise ratio (SNR), reference signal received power (RSRP), received signal strength indicator (RSSI), etc. The transmitter 1208 may include hardware, firmware, and / or software code executable by a processor to transmit data, where the code comprises instructions and is stored in a memory (e.g., a computer-readable medium). A suitable example of the transmitter 1208 may include, but is not limited to, an RF transmitter.

[0126] Moreover, in one aspect, the base station 102 may include an RF front end 1288 that may be in operative communication with the 3D Butler matrix 145, one or more antennas 144, and a transceiver 1202 for receiving and transmitting radio transmissions, e.g., wireless communications transmitted by other base stations 102 or wireless transmissions transmitted by the UE 104. The RF front end 1288 may be connected to the one or more antennas 144 via the 3D Butler matrix 145 and may include one or more low noise amplifiers (LNAs) 1290, one or more switches 1292, one or more power amplifiers (PAs) 1298, and one or more filters 1296 for transmitting and receiving RF signals.

[0127] In one aspect, the LNAs 1290 can amplify the received signal at a desired power level. In one aspect, each LNA 1290 can have a specified minimum and maximum gain value. In one aspect, the RF front end 1288 can use one or more switches 1292 to select a particular LNA 1290 and its specified gain value based on the desired gain value for a particular application.

[0128] Additionally, for example, one or more PAs 1298 may be used by the RF front end 1288 to amplify the signal for RF output at a desired output power level. In one aspect, each PA 1298 may have a specified minimum and maximum gain value. In one aspect, the RF front end 1288 may use one or more switches 1292 to select a particular PA 1298 and its specified gain value based on the desired gain value for a particular application.

[0129] Also, one or more filters 1296 may be used by the RF front end 1288, for example, to filter a received signal to obtain an input RF signal. Similarly, in an aspect, a respective filter 1296 may be used, for example, to filter an output from a respective PA 1298 to generate an output signal for transmission. In an aspect, each filter 1296 may be connected to a particular LNA 1290 and / or PA 1298. In an aspect, the RF front end 1288 may use one or more switches 1292 to select a transmit path or a receive path that uses a specified filter 1296, LNA 1290, and / or PA 1298 based on a configuration as specified by the transceiver 1202 and / or processor 1212.

[0130] Thus, the transceiver 1202 may be configured to transmit and receive wireless signals through one or more antennas 144 via the 3D Butler matrix 145 and the RF front end 1288. In one aspect, the transceiver 1202 may be tuned to operate at a designated frequency so that the base station 102 can communicate with, for example, one or more UEs 104, or one or more cells associated with one or more other base stations 102. In one aspect, for example, the modem 140 may configure the transceiver 1202 to operate at a designated frequency and power level based on the base station configuration of the base station 102 and the communication protocol used by the modem 140.

[0131] In one aspect, the modem 140 may be a multi-band multi-mode modem that can process digital data and communicate with the transceiver 1202 so that the digital data is sent and received using the transceiver 1202. In one aspect, the modem 140 may be multi-band and configured to support multiple frequency bands for a particular communication protocol. In one aspect, the modem 140 may be multi-mode and configured to support multiple operating networks and communication protocols. In an aspect, the modem 140 can control one or more components of the base station 102 (e.g., the RF front end 1288, the transceiver 1202, the 3D Butler matrix 145) to enable transmission and / or reception of signals from the network based on a specified modem configuration. In one aspect, the modem configuration can be based on the modem's mode and the frequency band in use. In another aspect, the modem configuration can be based on base station configuration information associated with the base station 102.

[0132] In an aspect, the processor 1212 may correspond to one or more of the processors described above with reference to the base station 1110 of Figure 11. Similarly, the memory 1216 may correspond to the memory described above with reference to the base station 1110 of Figure 11.

[0133] In one configuration, the base station 102 or the base station 1110 may be an apparatus for multi-antenna wireless communication, including means for implementing any of the appended claims for multi-antenna wireless communication by a base station. The means may be one or more of the above-mentioned components of the base station 102 and / or the processor 1212 of the base station 102 configured to perform the functions recited by the means. As explained above, the processor 1212 may include the TX processor 1116, the RX processor 1170, and the controller / processor 1175 of the base station 1110 described above with reference to FIG. 11 . Thus, in one configuration, the means may be the TX processor 1116, the RX processor 1170, and the controller / processor 1175 configured to perform the functions recited by the means.

[0134] Some Further Exemplary Implementations 1. An exemplary apparatus for multi-antenna wireless communications, comprising: a first-layer two-dimensional (2D) Butler matrix having first-layer input ports and first-layer output ports; a second-layer 2D Butler matrix having second-layer input ports and second-layer output ports; and a first-layer-second-layer switch configurable to selectively connect the first-layer output ports of the first-layer 2D Butler matrix to at least a subset of the second-layer input ports of the second-layer 2D Butler matrix based on a control signal applied to a control input pin of the first-layer-second-layer switch.

[0135] the above exemplary apparatus, wherein each of the first layer 2D Butler matrix and the second layer 2D Butler matrix comprises at least one Butler matrix having input ports and output ports, the at least one Butler matrix operable to activate all of the output ports in response to activation of each of the input ports with a uniform phase distribution and a constant phase difference between adjacent output ports, and wherein different input ports of the at least one Butler matrix, when activated, cause different phase patterns on the output ports of the at least one Butler matrix.

[0136] Any of the above example devices, wherein the device further comprises an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second layer 2D Butler matrix.

[0137] Any of the exemplary apparatuses described above, wherein each of the plurality of antenna elements is coupled to an output port of the second layer 2D Butler matrix via a configurable circuit comprising one or more switches or amplifiers, the configurable circuit being configurable in a receive mode for signal reception by the array antenna and also in a transmit mode for signal transmission by the array antenna.

[0138] Any of the above example apparatuses, further comprising: a modem operable to select one or more input ports of the first layer 2D Butler matrix for communication of one or more streams via one or more beams by the array antenna.

[0139] Any of the above example devices further comprising a transceiver operable as a transmitter to output one or more streams or as a receiver to input one or more streams.

[0140] Any of the above example apparatuses, wherein different input ports of the first layer 2D Butler matrix correspond to different beam azimuth or elevation angles, and wherein the modem is further operable to select one or more input ports associated with a desired beam azimuth or elevation angle.

[0141] Any of the above exemplary apparatuses, wherein the modem is further operable to apply a control signal to a control input pin of the first-second layer switch, the control signal being associated with a desired beam azimuth or elevation angle.

[0142] Any of the above exemplary apparatuses, wherein the first layer 2D Butler matrix includes a single Butler matrix, and the second layer 2D Butler matrix includes multiple Butler matrices, and each input port of the single Butler matrix is ​​associated with a different beam azimuth or elevation angle.

[0143] Any of the above exemplary devices, wherein the modem is further operable to apply a control signal to a control input pin of the first layer-second layer switch, the control signal indicating a desired beam azimuth or elevation angle, and the control signal controls the first layer-second layer switch to connect an output port of the first layer 2D Butler matrix to one selected input port of each Butler matrix in the second layer 2D Butler matrix.

[0144] Any of the above exemplary apparatuses, wherein the modem is operable to select only one input port of a single Butler matrix, corresponding to only one beam azimuth or elevation angle, at any given time.

[0145] Any of the above exemplary apparatuses, wherein the modem is operable to select two or more of the input ports of a single Butler matrix corresponding to two or more beam azimuth or elevation angles.

[0146] Any of the above exemplary apparatuses, wherein the modem is operable to apply a control signal to a control input pin of the first layer-second layer switch, the control signal indicating only one beam azimuth or elevation angle associated with only one input port in each Butler matrix in the second layer 2D Butler matrix.

[0147] Any of the above exemplary apparatuses, wherein the modem is further operable to apply a control signal to a control input pin of the first layer-second layer switch, the control signal indicating two or more beam azimuth or elevation angles associated with two or more input ports in each Butler matrix in the second layer 2D Butler matrix.

[0148] Any of the above example devices, where the device includes a base station or user equipment (UE).

[0149] 1. An exemplary method of multi-antenna wireless communication comprising: selecting one or more input ports of a first-layer two-dimensional (2D) Butler matrix for communication of one or more streams via one or more beams with an array antenna; applying control signals to control input pins of a first-layer-to-second-layer switch, the first-layer-to-second-layer switch being configurable to selectively connect first-layer output ports of the first-layer 2D Butler matrix to at least a subset of second-layer input ports of a second-layer 2D Butler matrix based on the control signals; and transmitting or receiving the one or more streams via the one or more beams with the array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second-layer 2D Butler matrix.

[0150] The above example method further comprising operation of any of the above apparatuses for multi-antenna wireless communication.

[0151] 10. An apparatus comprising: a transceiver; a memory configured to store instructions; and one or more processors communicatively coupled to the transceiver and the memory, the one or more processors configured to execute instructions to perform operations of any of the above methods of multi-antenna wireless communication.

[0152] An apparatus for wireless communication, comprising: means for performing the operations of any of the above methods for multi-antenna wireless communication.

[0153] A computer-readable storage medium comprising code executable by one or more processors to perform the operations of any of the above methods of multi-antenna wireless communication.

[0154] It is understood that the specific order or hierarchy of blocks in the disclosed processes / flowcharts is illustrative of example approaches. Based on design preferences, it is understood that the specific order or hierarchy of blocks in the processes / flowcharts may be rearranged. Further, some blocks may be combined or omitted. 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.

[0155] The above description is provided to enable any 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 general principles defined herein may be applied to other aspects. Accordingly, the claims are not intended to be limited to the aspects shown herein but are to be accorded the widest scope consistent with the claim language, and reference to an element in the singular does not mean "one and only," unless so expressly stated, but rather "one or more." The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" should not necessarily be construed as preferred or advantageous over other aspects. Unless expressly stated otherwise, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiple As, multiple Bs, or multiple Cs. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, and any such combination may include one or more members of A, B, or C. All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known, or that later become known, to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be made public, regardless of whether such disclosure is expressly recited in the claims.Words such as "module," "mechanism," "element," "device," etc. may not be substitutes for the word "means." Thus, no element of a claim should be construed as a means-plus-function unless the element is expressly recited using the phrase "means for." [Explanation of symbols]

[0156] 100 Wireless Communication Systems and Access Networks 102 Base station 102' Small Cell 104UE 110 Geographic Coverage Areas 110' coverage area 120 Communication Links 132 backhaul links 134 backhaul links 140 modem 141 First Layer 2D Butler Matrix 142 Layer 1-Layer 2 Switch 143 Second Layer 2D Butler Matrix 144 2D Array Antenna 145 3D Butler Matrix 150 AP 152 STA 154 communication links 158 D2D communication links 160 EPC 162 MME 164 MME 166 Serving Gateway 168 MBMS Gateway 170 BM-SC 172 PDN Gateway 174 Home Subscriber Server 176 IP Services 180 gNB 182 Beamforming 182' Sending direction 182'' receiving direction 184 backhaul links 190 Core Network 192 AMF 193 AMF 194 SMF 195 UPF 196 UDM 197 IP Services 300 4x4 Butler Matrix 304 Hybrid Coupler 306 Crossover 308 input port 310 output port 312 Antenna Element 314 Array Antenna 316 Desired Beam 400 3D Butler Matrix 402 4x4 array antenna 403 Antenna Element 404 First Layer 2D Butler Matrix 406 Second Layer 2D Butler Matrix 408 4x4 Butler Matrix 600 3D Butler Matrix 602 16×4 URA 603 Antenna Element 604 Second Layer 2D Butler Matrix 606 First Layer 2D Butler Matrix 610 4x4 Butler Matrix 700 3D Butler Matrix 702 4x4 array antenna 703 Antenna Elements 704 First Layer 2D Butler Matrix 706 Second Layer 2D Butler Matrix 708 4x4 Butler Matrix 710 Layer 1-Layer 2 Switch 712 control input pins 713 Control Signal 800 3D Butler Matrix 802 16×4 URA 804 Second Layer 2D Butler Matrix 806 First Layer 2D Butler Matrix 808 16x16 Butler Matrix 812 Layer 1-Layer 2 Switch 814 control input pins 1002 Transceiver 1006 Receiver 1008 Transmitter 1012 processors 1016 memory 1044 Bus 1075 Applications 1088 RF Front End 1090 LNA 1092 Switch 1096 filters 1098 PA 1110 base station 1116 TX Processor 1118 Transceiver 1118TX Transmitter 1118RX Receiver 1120 Antenna 1150 UE 1152 Antenna 1154 Transceiver 1154RX receiver 1154TX transmitter 1156 RX processor 1158 Channel Estimator 1159 Controller / Processor 1160 memory 1168 TX Processor 1170 RX processor 1175 Controller / Processor 1176 memory 1202 transceiver 1206 Receiver 1208 Transmitter 1212 processor 1216 memory 1224 Bus 1288 RF Front End 1290 LNA 1292 Switch 1296 filters 1298 PA

Claims

1. 1. An apparatus for multi-antenna wireless communication, comprising: a first-layer two-dimensional (2D) Butler matrix having a first-layer input port and a first-layer output port; a second-layer 2D Butler matrix having a second-layer input port and a second-layer output port; a layer 1-layer 2 switch, the layer 1-layer 2 switch being configurable to selectively connect the first layer output ports of the first layer 2D Butler matrix to at least a subset of the second layer input ports of the second layer 2D Butler matrix based on a control signal applied to a control input pin of the layer 1-layer 2 switch; Equipped with the first-layer-second-layer switch, when the first layer output port of the first layer 2D Butler matrix is ​​activated, activates the same number of input ports in each of a plurality of Butler matrices in the second layer 2D Butler matrix.

2. 2. The apparatus of claim 1, wherein the first layer 2D Butler matrix and the second layer 2D Butler matrix each comprise at least one Butler matrix having input ports and output ports, the at least one Butler matrix operable to activate all of the output ports in response to activation of each of the input ports with a uniform phase distribution and a constant phase difference between adjacent output ports, and wherein different input ports of the at least one Butler matrix, when activated, induce different phase patterns on the output ports of the at least one Butler matrix.

3. 3. The apparatus of claim 2, further comprising an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements associated with one output port of the second layer 2D Butler matrix.

4. 4. The apparatus of claim 3, wherein each of the plurality of antenna elements is coupled to an output port of the second layer 2D Butler matrix via a configurable circuit comprising one or more switches or amplifiers, the configurable circuit being configurable in a receive mode for signal reception by the array antenna and also in a transmit mode for signal transmission by the array antenna.

5. 4. The apparatus of claim 3, further comprising: a modem operable to select one or more input ports of the first layer 2D Butler matrix for communication of one or more streams via one or more beams by the array antenna.

6. The apparatus of claim 5 , further comprising a transceiver operable as a transmitter to output the one or more streams or as a receiver to input the one or more streams.

7. 6. The apparatus of claim 5, wherein different input ports of the first layer 2D Butler matrix correspond to different beam azimuth or elevation angles, and wherein the modem is further operable to select the one or more input ports associated with a desired beam azimuth or elevation angle.

8. 6. The apparatus of claim 5, wherein the modem is further operable to apply a control signal to the control input pin of the first-to-second layer switch, the control signal being associated with a desired beam azimuth or elevation angle.

9. 6. The apparatus of claim 5, wherein the first layer 2D Butler matrix includes a single Butler matrix and the second layer 2D Butler matrix includes multiple Butler matrices, each input port of the single Butler matrix being associated with a different beam azimuth or elevation angle.

10. the modem is further operable to apply a control signal to the control input pin of the first-to-second layer switch, the control signal indicating a desired beam azimuth or elevation angle, and the control signal controls the first-to-second layer switch to connect an output port of the first layer 2D Butler matrix to one selected input port of each Butler matrix in the second layer 2D Butler matrix; or the modem is operable to select only one input port of the single Butler matrix corresponding to only one beam azimuth or elevation angle at any given time; or the modem is operable to select two or more of the input ports of the single Butler matrix corresponding to two or more beam azimuth or elevation angles; or the modem is operable to apply a control signal to the control input pin of the first layer to second layer switch, the control signal indicating only one beam azimuth or elevation angle associated with only one input port in each Butler matrix in the second layer 2D Butler matrix; or 10. The apparatus of claim 9, wherein the modem is further operable to apply control signals to the control input pins of the first-to-second layer switches, the control signals indicating two or more beam azimuth or elevation angles associated with two or more input ports in each Butler matrix in the second layer 2D Butler matrix.

11. The apparatus of claim 1 , wherein the apparatus comprises a base station.

12. The apparatus of claim 1 , wherein the apparatus comprises a user equipment (UE).

13. 1. A method of multi-antenna wireless communication, comprising: selecting one or more input ports of a first-layer two-dimensional (2D) Butler matrix for communication of one or more streams via one or more beams by the array antenna; applying control signals to control input pins of first-layer-second-layer switches, the first-layer-second-layer switches being configurable to selectively connect first-layer output ports of the first-layer 2D Butler matrix to at least a subset of second-layer input ports of a second-layer 2D Butler matrix based on the control signals; transmitting or receiving one or more streams via one or more beams with an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second layer 2D Butler matrix; Including, wherein the first-to-second layer switch activates the same number of input ports in each of a plurality of Butler matrices in the second layer 2D Butler matrix when the first layer output port of the first layer 2D Butler matrix is ​​activated.

14. 1. An apparatus for multi-antenna wireless communication, comprising: means for selecting one or more input ports of the first layer two-dimensional (2D) Butler matrix for communication of one or more streams via one or more beams by the array antenna; means for applying control signals to control input pins of the first-layer-second-layer switches, the first-layer-second-layer switches being configurable to selectively connect first layer output ports of the first layer 2D Butler matrix to at least a subset of second layer input ports of a second layer 2D Butler matrix based on the control signals; means for transmitting or receiving one or more streams via one or more beams by an array antenna, the array antenna including a plurality of antenna elements, each of the plurality of antenna elements being associated with one output port of the second layer 2D Butler matrix; the first-layer-second-layer switch, when the first layer output port of the first layer 2D Butler matrix is ​​activated, activates the same number of input ports in each of a plurality of Butler matrices in the second layer 2D Butler matrix.

15. A computer program comprising instructions which, when executed by a computer, cause the computer to perform the steps of claim 13.

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