WO2018071026A1

WO2018071026A1 - Directional channel measurement in hybrid beamforming architecture

Info

Publication number: WO2018071026A1
Application number: PCT/US2016/056816
Authority: WO
Inventors: Roya Doostnejad; Wook Bong Lee; Jing Zhu
Original assignee: Intel Corporation
Priority date: 2016-10-13
Filing date: 2016-10-13
Publication date: 2018-04-19

Abstract

Hybrid beam-forming (BF) radio communications are carried out between a base station (BS) and a set of user equipment (UEs) within a service area. The hybrid BF operations include a sector-sweep operation to identify analog beam-forming (BF) parameters for individual ones of the set UEs within the service area. A first subset of UEs is selected from among the set of UEs, the first subset of UEs being subject to channel quality assessment (CQA). The UEs of the first subset are configured to transmit CQA signaling, the CQA signaling being based on the analog BF parameters. Digital BF parameters are computed for the UEs of the first subset based on the CQA signaling.

Description

DIRECTIONAL CHANNEL MEASUREMENT

IN HYBRID BEAMFORMING ARCHITECTURE

TECHNICAL FIELD

[0001] Embodiments pertain to wireless communications. Some embodiments relate to wireless networks including 3GPP (Third Generation Partnership Project) networks, 3GPP LTE (Long Term Evolution) networks, 3 GPP LTE-A (LTE Advanced) networks, and fifth-generation (5G) networks. Other embodiments relate to Wi-Fi wireless local area networks (WLANs). Further embodiments are more generally applicable outside the purview of LTE and Wi-Fi networks. Aspects of the embodiments are directed to channel measurements, digital processing and multiuser scheduling in systems utilizing hybrid beamforming technologies.

BACKGROUND

[0002] In conventional digital beamforming (BF) systems, cell-specific channel measurements may be performed for multiple-input, multiple-output (MIMO) mode selection, multiuser scheduling and in defining the BF weights. In hybrid BF architectures for millimeter wave (mm Wave) channels, as a result of the added analog BF control, the analog beam-formed channel has to be measured for every user. Therefore, conventionally, channels are measured in a user-specific manner. This causes longer delays as well as more complications in multiuser (MU) scenarios, such as MU scheduling. Moreover, in multiuser BF systems, where each of a set of RF chains is steering a beam towards a certain user, the effective analog beam-formed channel is dependent on the selected paired users and their analog BF weights. As a complication, in order to select user pairings for MU transmission, the measurements of the effective channel are made. This situation presents a variety of challenges in multiuser scheduling and BF operations in hybrid BF architectures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. Some embodiments are illustrated by way of example, and not limitation, in the following figures of the accompanying drawings.

[0004] FIG. 1 is a functional diagram of a 3GPP network in accordance with some embodiments.

[0005] FIG. 2 is a block diagram of a User Equipment (UE) in accordance with some embodiments.

[0006] FIG. 3 is a block diagram of an Evolved Node-B (eNB) in accordance with some embodiments.

[0007] FIG. 4 illustrates an example processor-based computing platform according to some embodiments.

[0008] FIG. 5 illustrates examples of multiple beam transmission in accordance with some embodiments.

[0009] FIG. 6 is a diagram illustrating a MIMO transmission scenario utilizing an eNB and a UE, each having multiple antennas according to some embodiments.

[0010] FIG.7 is a diagram illustrating an exemplary communication network scenario in accordance with some embodiments.

[0011] FIG. 8 shows an example hybrid beamforming system architecture in accordance with some embodiments.

[0012] FIG. 9 A is a process flow diagram illustrating an example set of high-level operations to be performed by an eNB or base station (BS) that supports hybrid beamforming (BF) according to some embodiments.

[0013] FIG. 9B is a flow diagram illustrating example operations that are included in the selection of a subset of UEs for channel quality assessment (CQA) of according to some example embodiments.

[0014] FIGs. 9C and 9D illustrate various embodiments for carrying out CQA operations according to some embodiments.

[0015] FIGs. lOA-lOC are time-frequency diagrams illustrating example use cases in which the process of FIG.9 A is applied in a system that utilizes frequency division multiplexing (FDM) to multiplex CQA signaling transmitted from different antenna ports in the frequency domain in accordance with some embodiments.

[0016] FIG. 11 is a flow diagram illustrating an example process utilizing a preliminary sector-specific CQA according to some embodiments. DETAILED DESCRIPTION

[0017] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. A number of examples are described in the context of 3 GPP communication systems and components thereof. It will be understood that principles of the embodiments are applicable in other types of communication systems, such as Wi-Fi or Wi-Max networks, Bluetooth or other personal-area networks (PANs), Zigbee or other home- area networks (HANs), wireless mesh networks, and the like, without limitation, unless expressly limited by a corresponding claim.

[0018] Given the benefit of the present disclosure, persons skilled in the relevant technologies will be able to engineer suitable variations to implement principles of the embodiments in other types of communication systems. For example, it will be understood that a base station or e-Node B (eNB) of a 3GPP context is analogous, generally speaking, to a wireless access point (AP) of a WLAN context. Likewise, user equipment (UE) of a 3GPP context is generally analogous to mobile stations (STAs) of WLANs. Various diverse embodiments may incorporate structural, logical, electrical, process, and other differences. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all presently-known, and after- arising, equivalents of those claims.

[0019] FIG. 1 is a functional diagram of a 3 GPP network in accordance with some embodiments. The network comprises a radio access network (RAN) (e.g., as depicted, the E-UTRAN or evolved universal terrestrial radio access network) 101 and the core network 120 (e.g., shown as an evolved packet core (EPC)) coupled together through an SI interface 115. For convenience and brevity sake, only a portion of the core network 120, as well as the RAN 101, is shown.

[0020] The core network 120 includes a mobility management entity (MME) 122, a serving gateway (serving GW) 124, and packet data network gateway (PDN GW) 126. The RAN 101 includes Evolved Node-B's (eNB) 104 (which may operate as base stations) for communicating with User Equipment (UE) 102. Hereinafter, the terms eNB and base station (BS) may be used interchangeably unless a specific distinction is intended, in which case the distinction will be specifically pointed out The eNBs 104 may include macro eNBs and low power (LP) eNBs. In accordance with some embodiments, the eNB 104 may transmit a downlink control message to the UE 102 to indicate an allocation of physical uplink control channel (PUCCH) channel resources. The UE 102 may receive the downlink control message from the eNB 104, and may transmit an uplink control message to the eNB 104 in at least a portion of the PUCCH channel resources. These embodiments will be described in more detail below.

[0021] The MME 122 is similar in function to the control plane of legacy Serving GPRS Support Nodes (SGSN). The MME 122 manages mobility aspects in access such as gateway selection and tracking area list management. The serving GW 124 terminates the interface toward the RAN 101, and routes data packets between the RAN 101 and the core network 120. In addition, it may be a local mobility anchor point for inter-eNB handoffs and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement. The serving GW 124 and the MME 122 may be implemented in one physical node or separate physical nodes. The PDN GW 126 terminates a SGi interface toward the packet data network (PDN). The PDN GW 126 routes data packets between the EPC 120 and the external PDN, and may be a key node for policy enforcement and charging data collection. It may also provide an anchor point for mobility with non-LTE accesses. The external PDN can be any kind of IP network, as well as an IP Multimedia Subsystem (IMS) domain. The PDN GW 126 and the serving GW 124 may be implemented in one physical node or separated physical nodes.

[0022] The eNB 104 (macro and micro) terminate the air interface protocol and may be the first point of contact for a UE 102. In some embodiments, an eNB 104 may fulfill various logical functions for the RAN 101 including but not limited to RNC (radio network controller functions) such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. In accordance with embodiments, UE 102 may be configured to communicate with an eNB 104 over a multipath fading channel in accordance with an Orthogonal Frequency Division Multiple Access (OFDMA) communication technique. The OFDM signals may comprise a plurality of orthogonal subcarriers.

[0023] The S 1 interface 1 IS is the interface that separates the RAN 101 and the EPC 120. It is split into two parts: the Sl-U, which carries traffic data between the eNB 104 and the serving GW 124, and the Sl-MME, which is a signaling interface between the eNB 104 and the MME 122. The X2 interface is the interface between eNB 104. The X2 interface comprises two parts, the X2-C and X2-U. The X2-C is the control plane interface between the eNB 104, while the X2-U is the user plane interface between the eNB 104.

[0024] With cellular networks, LP cells are typically used to extend coverage to indoor areas where outdoor signals do not reach well, or to add network capacity in areas with very dense phone usage, such as train stations. As used herein, the term low power (IP) eNB refers to any suitable relatively low power eNB for

implementing a narrower cell (narrower than a macro cell) such as a femtocell, a picocell, or a micro cell. Femtocell eNBs are typically provided by a mobile network operator to its residential or enterprise customers. A femtocell is typically the size of a residential gateway or smaller and generally connects to the user's broadband line. Once plugged in, the femtocell connects to the mobile operator's mobile network and provides extra coverage in a range of typically 30 to SO meters for residential femtocells. Thus, a LP eNB might be a femtocell eNB since it is coupled through the PDN GW 126. Similarly, a picocell is a wireless communication system typically covering a small area, such as in-building (offices, shopping malls, train stations, etc.), or more recently in-aircraft. A picocell eNB can generally connect through the X2 link to another eNB such as a macro eNB through its base station controller (BSC) functionality. Thus, LP eNB may be implemented with a picocell eNB since it is coupled to a macro eNB via an X2 interface. Picocell eNBs or other LP eNBs may incorporate some or all functionality of a macro eNB. In some cases, this may be referred to as an access point base station or enterprise femtocell.

[0025] In some embodiments, a downlink resource grid may be used for downlink transmissions from an eNB 104 to a UE 102, while uplink transmission from the UE 102 to the eNB 104 may utilize similar techniques. The grid may be a time-frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid correspond to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time- frequency unit in a resource grid is denoted as a resource element (RE). Each resource grid comprises a number of resource blocks (RBs), which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements in the frequency domain and may represent the smallest quanta of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks. With particular relevance to this disclosure, two of these physical downlink channels are the physical downlink shared channel and the physical down link control channel.

[0026] The physical downlink shared channel (PDSCH) carries user data and higher-layer signaling to a UE 102 (FIG. 1). The physical downlink control channel (PDCCH) carries information about the transport format and resource allocations related to the PDSCH channel, among other things. It also informs the UE 102 about the transport format, resource allocation, and hybrid automatic repeat request (HARQ) information related to the uplink shared channel. Typically, downlink scheduling (e.g., assigning control and shared channel resource blocks to UE 102 within a cell) may be performed at the eNB 104 based on channel quality information fed back from the UE 102 to the eNB 104, and then the downlink resource assignment information may be sent to the UE 102 on the control channel (PDCCH) used for (assigned to) the UE 102.

[0027] The PDCCH uses CCEs (control channel elements) to convey the control information. Before being mapped to resource elements, the PDCCH complex- valued symbols are first organized into quadruplets, which are then permuted using a sub-block inter-leaver for rate matching. Each PDCCH is transmitted using one or more of these control channel elements (CCEs), where each CCE corresponds to nine sets of four physical resource elements known as resource element groups (REGs). Four QPSK symbols are mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of downlink control information (DO) and the channel condition. There may be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=l, 2, 4, or 8).

[0028] As used herein, the term circuitry may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), or memory (shared, dedicated, or group) that executes one or more software or firmware programs, a combinational logic circuit, or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware. Embodiments described herein may be implemented into a system using any suitably configured hardware or software.

[0029] FIG. 2 is a functional diagram of a User Equipment (UE) in accordance with some embodiments. The UE 200 may be suitable for use as a UE 102 as depicted in FIG. 1. In some embodiments, the UE 200 may include application circuitry 202, baseband circuitry 204, Radio Frequency (RF) circuitry 206, front-end module (FEM) circuitry 208 and multiple antennas 210A-210D, coupled together at least as shown. In some embodiments, other circuitry or arrangements may include one or more elements or components of the application circuitry 202, the baseband circuitry 204, the RF circuitry 206 or the FEM circuitry 208, and may also include other elements or components in some cases. As an example, "processing circuitry" may include one or more elements or components, some or all of which may be included in the application circuitry 202 or the baseband circuitry 204. As another example, "transceiver circuitry" may include one or more elements or components, some or all of which may be included in the RF circuitry 206 or the FEM circuitry 208. These examples are not limiting, however, as the processing circuitry or the transceiver circuitry may also include other elements or components in some cases.

[0030] The application circuitry 202 may include one or more application processors. For example, the application circuitry 202 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processors) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the system.

[0031] The baseband circuitry 204 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 204 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 206 and to generate baseband signals for a transmit signal path of the RF circuitry 206. Baseband processing circuity 204 may interface with the application circuitry 202 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 206. For example, in some embodiments, the baseband circuitry 204 may include a second generation (2G) baseband processor 204a, third generation (3G) baseband processor 204b, fourth generation (4G) baseband processor 204c, or other baseband processors) 204d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (SG), 6G, etc.). The baseband circuitry 204 (e.g., one or more of baseband processors 204a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 206. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 204 may include Fast-Fourier Transform (FFT), precoding, or constellation

mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 204 may include Low Density Parity Check (LDPC) encoder/decoder functionality, optionally along-side other techniques such as, for example, block codes, convolutional codes, turbo codes, or the like, which may be used to support legacy protocols. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0032] In some embodiments, the baseband circuitry 204 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), or radio resource control (RRC) elements. A central processing unit (CPU) 204e of the baseband circuitry 204 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processors) (DSP) 204f. The audio DSP(s) 204f maybe include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 204 and the application circuitry 202 may be implemented together such as, for example, on a system on chip (SOC).

[0033] In some embodiments, the baseband circuitry 204 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 204 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 204 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0034] RF circuitry 206 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium In various embodiments, the RF circuitry 206 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 206 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 208 and provide baseband signals to the baseband circuitry 204. RF circuitry 206 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 204 and provide RF output signals to the FEM circuitry 208 for transmission.

[0035] In some embodiments, the RF circuitry 206 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 206 may include mixer circuitry 206a, amplifier circuitry 206b and filter circuitry 206c. The transmit signal path of the RF circuitry 206 may include filter circuitry 206c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206d for synthesizing a frequency for use by the mixer circuitry 206a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 206a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 208 based on the synthesized frequency provided by synthesizer circuitry 206d. The amplifier circuitry 206b may be configured to amplify the down- converted signals and the filter circuitry 206c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down- converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 204 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 206a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect. In some embodiments, the mixer circuitry 206a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 206d to generate RF output signals for the FEM circuitry 208. The baseband signals may be provided by the baseband circuitry 204 and may be filtered by filter circuitry 206c. The filter circuitry 206c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[003(6] In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion or upconversion respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a may be arranged for direct downconversion or direct upconversion, respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may be configured for super-heterodyne operation.

[0037] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 206 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 204 may include a digital baseband interface to communicate with the RF circuitry 206. In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0038] In some embodiments, the synthesizer circuitry 206d may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the

embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 206d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase- locked loop with a frequency divider. The synthesizer circuitry 206d may be configured to synthesize an output frequency for use by the mixer circuitry 206a of the RF circuitry 206 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 206d may be a fractional N/N+l synthesizer. In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 204 or the applications processor 202 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 202.

[0039] Synthesizer circuitry 206d of the RF circuitry 206 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DP A). In some embodiments, the DMD may be configured to divide the input signal by either N or N+l (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0040] In some embodiments, synthesizer circuitry 206d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fix_>). In some embodiments, the RF circuitry 206 may include an lQ/polar converter.

[0041] FEM circuitry 208 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more of the antennas 210A-D, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 206 for further processing. FEM circuitry 208 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 206 for transmission by one or more of the one or more antennas 210A-D. [0042] In some embodiments, the FEM circuitry 208 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 206). The transmit signal path of the FEM circuitry 208 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 206), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 210. In some embodiments, the UE 200 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface.

[0043] FIG. 3 is a functional diagram of an Evolved Node-B (eNB) in accordance with some embodiments. It should be noted that in some embodiments, the eNB 300 may be a stationary non-mobile device. The eNB 300 may be suitable for use as an eNB 104 as depicted in FIG. 1. The components of eNB 300 may be included in a single device or a plurality of devices. The eNB 300 may include physical layer circuitry 302 and a transceiver 30S, one or both of which may enable transmission and reception of signals to and from the UE 200, other eNBs, other UEs or other devices using one or more antennas 301A-B. As an example, the physical layer circuitry 302 may perform various encoding and decoding functions that may include formation of baseband signals for transmission and decoding of received signals. For example, physical layer circuitry 302 may include LDPC encoder/decoder functionality, optionally along-side other techniques such as, for example, block codes, convolutional codes, turbo codes, or the like, which may be used to support legacy protocols. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments. As another example, the transceiver 30S may perform various transmission and reception functions such as conversion of signals between a baseband range and a Radio Frequency (RF) range. Accordingly, the physical layer circuitry 302 and the transceiver 305 may be separate components or may be part of a combined component. In addition, some of the described functionality related to transmission and reception of signals may be performed by a combination that may include one, any or all of the physical layer circuitry 302, the transceiver 305, and other components or layers. The eNB 300 may also include medium access control layer (MAC) circuitry 304 for controlling access to the wireless medium. The eNB 300 may also include processing circuitry 306 and memory 308 arranged to perform the operations described herein. The eNB 300 may also include one or more interfaces 310, which may enable communication with other components, including other eNB 104 (FIG. 1), components in the EPC 120 (FIG. 1) or other network components. In addition, the interfaces 310 may enable communication with other components that may not be shown in FIG. 1 , including components external to the network. The interfaces 310 may be wired or wireless or a combination thereof.

[0044] The antennas 210 A-D, 301 A-B may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some multiple-input multiple- output (MIMO) embodiments, the antennas 210A-D, 301 A-B may be effectively separated to take advantage of spatial diversity and the different channel

characteristics that may result.

[0045] In some embodiments, the UE 200 or the eNB 300 may be a mobile device and maybe a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an iastant messaging device, a digital camera, an access point, a television, a wearable device such as a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive or transmit information wirelessly. In some embodiments, the UE 200 or eNB 300 may be configured to operate in accordance with 3GPP standards, although the scope of the embodiments is not limited in this respect. Mobile devices or other devices in some embodiments may be configured to operate according to other protocols or standards, including IEEE 802.11 or other IEEE standards. In some embodiments, the UE 200, eNB 300 or other device may include one or more of a keyboard, a display, a non- volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.

[0046] Although the UE 200 and the eNB 300 are each illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functioas described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.

[0047] Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media. Some embodiments may include one or more processors and may be configured with instructions stored on a computer-readable storage device.

[0048] It should be noted that in some embodiments, an apparatus used by the UE 200 or eNB 300 may include various components of the UE 200 or the eNB 300 as shown in FIGs. 2-3. Accordingly, techniques and operations described herein that refer to the UE 200 (or 102) may be applicable to an apparatus for a UE. In addition, techniques and operations described herein that refer to the eNB 300 (or 104) may be applicable to an apparatus for an eNB.

[0049] FIG. 4 illustrates an example processor-based computing platform according to some embodiments. As depicted, system 400 includes one or more processors) 404, system control logic 408 coupled with at least one of the processor(s) 404, system memory 412 coupled with system control logic 408, nonvolatile memory (NVM)/storage 416 coupled with system control logic 408, a network interface 420 coupled with system control logic 408, and input/output (I/O) devices 432 coupled with system control logic 408.

[0050] The processors) 404 may include one or more single-core or multi-core processors. The processors) 404 may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, baseband processors, etc.).

[0051] System control logic 408 for one embodiment may include any suitable interface controllers to provide for any suitable interface to at least one of the processors) 404 and/or to any suitable device or component in communication with system control logic 408.

[0052] System control logic 408 for one embodiment may include one or more memory controller(s) to provide an interface to system memory 412. System memory 412 may be used to load and store data and/or instructions, e.g., communication logic 424. System memory 412 for one embodiment may include any suitable volatile memory, such as suitable dynamic random access memory (DRAM), for example.

[0053] NVM/storage 416 may include one or more tangible, non- transitory computer-readable media used to store data and/or instructions, e.g., communication logic 424. NVM/storage 416 may include any suitable non-volatile memory, such as flash memory, for example, and/or may include any suitable non- volatile storage device(s), such as one or more hard disk drive(s) (HDD(s)), one or more compact disk (CD) drive(s), and/or one or more digital versatile disk (DVD) drive(s), for example.

[0054] The NVM/storage 416 may include a storage resource physically part of a device on which the system 400 is installed or it may be accessible by, but not necessarily a part of, the device. For example, the NVM/storage 416 may be accessed over a network via the network interface 420 and/or over Input/Output (I/O) devices 432.

[0055] The communication logic 424 may include instructions that, when executed by one or more of the processors 404, cause the system 400 to perform operatioas associated with the components of the communication device IRP manager 128, IRP agent 132, mapping circuitry 136 and/or the methods 200 or 300 as described with respect to the above embodiments. In various embodiments, the communication logic 424 may include hardware, software, and/or firmware components that may or may not be explicitly shown in system 400.

[0056] Network interface 420 may have a transceiver 422 to provide a radio interface for system 400 to communicate over one or more network(s) and/or with any other suitable device. In various embodiments, the transceiver 422 may be integrated with other components of system 400. For example, the transceiver 422 may include a processor of the processor(s) 404, memory of the system memory 412, and NVM/Storage of NVM/Storage 416. Network interface 420 may include any suitable hardware and/or firmware. Network interface 420 may include a plurality of antennas to provide a multiple input, multiple output radio interface. Network interface 420 for one embodiment may include, for example, a wired network adapter, a wireless network adapter, a telephone modem, and/or a wireless modem.

[0057] For one embodiment, at least one of the processors) 404 may be packaged together with logic for one or more controllers) of system control logic 408. For one embodiment, at least one of the processors) 404 may be packaged together with logic for one or more controllers of system control logic 408 to form a System in Package (SiP). For one embodiment, at least one of the processors) 404 may be integrated on the same die with logic for one or more controllers) of system control logic 408. For one embodiment, at least one of the processors) 404 may be integrated on the same die with logic for one or more controller(s) of system control logic 408 to form a System on Chip (SoC).

[0058] In various embodiments, the I/O devices 432 may include user interfaces designed to enable user interaction with the system 400, peripheral component interfaces designed to enable peripheral component interaction with the system 400, and/or sensors designed to determine environmental conditions and/or location information related to the system 400.

[0059] In various embodiments, the user interfaces could include, but are not limited to, a display (e.g., a liquid crystal display, a touch screen display, etc.), speakers, a microphone, one or more cameras (e.g., a still camera and/or a video camera), a flashlight (e.g., a light emitting diode flash), and a keyboard.

[0060] In various embodiments, the peripheral component interfaces may include, but are not limited to, a non- volatile memory port, a universal serial bus (USB) port, an audio jack, an Ethernet connection, and a power supply interface.

[0061] In various embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity seasor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the network interface 420 to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite.

[0062] In various embodiments, the system 400 may be implemented on a server, or system of networked server machines. System 400 may also be virtualized in some embodiments on a host machine or on a set of host machines operating using distributed computing techniques. In other embodiments, system 400 may be implemented on one or more mobile computing devices such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, a smartphone, etc. In various embodiments, system 400 may have more or less components, and/or different architectures.

[0063] Examples, as described herein, may include, or may operate on, logic or a number of components, engines, modules, or circuitry which for the sake of consistency are termed engines, although it will be understood that these terms may be used interchangeably. Engines may be hardware, software, or firmware communicatively coupled to one or more processors in order to carry out the operations described herein. Engines may be hardware engines, and as such engines may be considered tangible entities capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as an engine. In an example, the whole or part of one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as an engine that operates to perform specified operations. In an example, the software may reside on a machine-readable medium. In an example, the software, when executed by the underlying hardware of the engine, causes the hardware to perform the specified operations. Accordingly, the term hardware engine is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein.

[0064] Considering examples in which engines are temporarily configured, each of the engines need not be instantiated at any one moment in time. For example, where the engines comprise a general-purpose hardware processor core configured using software; the general-purpose hardware processor core may be configured as respective different engines at different times. Software may accordingly configure a hardware processor core, for example, to constitute a particular engine at one instance of time and to constitute a different engine at a different instance of time.

[0065] FIG. 5 illustrates examples of multiple beam transmission in accordance with some embodiments. Although the example scenarios 500 and 550 depicted in FIG. S may illustrate some aspects of techniques disclosed herein, it will be understood that embodiments are not limited by example scenarios 500 and SS0. Embodiments are not limited to the number or type of components shown in FIG. 5 and are also not limited to the number or arrangement of transmitted beams shown in FIG. 5.

[0066] In example scenario 500, the eNB 104 may transmit a signal on multiple beams 505-520, any or all of which may be received at the UE 102. It should be noted that the number of beams or transmission angles as shown are not limiting. As the beams 505-520 may be directional, transmitted energy from the beams 505-520 may be concentrated in the direction shown. Therefore, the UE 102 may not necessarily receive a significant amount of energy from beams 505 and 510 in some cases, due to the relative location of the UE 102.

[0067] UE 102 may receive a significant amount of energy from the beams 515 and 520 as shown. As an example, the beams 505-520 may be transmitted using different reference signals, and the UE 102 may determine channel-state information (CSI) feedback or other information for beams 515 and 520. In some embodiments, each of beams 505-520 are configured as CSI reference signals (CSI-RS). In related embodiments, the CSI-RS signal is a part of the discovery reference signaling (DRS) configuration. The DRS configuration may serve to inform the UE 102 about the physical resources (e.g., subframes, subcarriers) on which the CSI-RS signal will be found. In related embodiments, the UE 102 is further informed about any scrambling sequences that are to be applied for CSI-RS.

[0068] In some embodiments, up to 2 MIMO layers may be transmitted within each beam by using different polarizations. More than 2 MIMO layers may be transmitted by using multiple beams. In related embodiments, the UE is configured to discover the available beams and report those discovered beams to the eNB prior to the MIMO data transmissions using suitable reporting messaging, such as channel-state reports (CSR), for example. Based on the reporting messaging, the eNB 104 may determine suitable beam directions for the MIMO layers to be used for data communications with the UE 102. In various embodiments, there may be up to 2, 4, 8, 16, 32, or more MIMO layers, depending on the number of MIMO layers that are supported by the eNB 104 and UE 102. In a given scenario, the number of MIMO layers that may actually be used will depend on the quality of the signaling received at the UE 102, and the availability of reflected beams arriving at diverse angles at the UE 102 such that the UE 102 may discriminate the data carried on the separate beams.

[0069] In the example scenario 550, the UE 102 may determine angles or other information (such as CSI feedback, channel-quality indicator (CQI) or other) for the beams 565 and 570. The UE 102 may also determine such information when received at other angles, such as the illustrated beams 575 and 580. The beams 575 and 580 are demarcated using a dotted line configuration to indicate that they may not necessarily be transmitted at those angles, but that the UE 102 may determine the beam directions of beams 575 and 580 using such techniques as receive beam- forming, as receive directions. This situation may occur, for example, when a transmitted beam reflects from an object in the vicinity of the UE 102, and arrives at the UE 102 according to its reflected, rather than incident, angle.

[0070] In some embodiments, the UE 102 may transmit one or more channel state information (CSI) messages to the eNB 104 as reporting messaging. Embodiments are not limited to dedicated CSI messaging, however, as the UE 102 may include relevant reporting information in control messages or other types of messages that may or may not be dedicated for communication of the CSI-type information.

[0071] As an example, the first signal received from the first eNB 104 may include a first directional beam based at least partly on a first CSI-RS signal and a second directional beam based at least partly on a second CSI-RS signal. The UE 102 may determine a rank indicator (RI) for the first CSI-RS and an RI for the second CSI-RS, and may transmit both RIs in the CSI messages. In addition, the UE 102 may determine one or more RIs for the second signal, and may also include them in the CSI messages in some cases. In some embodiments, the UE 102 may also determine a CQI, a precoding matrix indicator (ΡΜΓ), receive angles or other information for one or both of the first and second signals. Such information may be included, along with one or more RIs, in the one or more CSI messages. In some embodiments, the UE 102 performs reference signal receive power (RSRP) measurement, received signal strength indication (RSSI) measurement, reference signal receive quality (RSRQ) measurement, or some combination of these using CSI-RS signals.

[0072] FIG. 6 is a diagram illustrating a MIMO transmission scenario utilizing an eNB and a UE, each having multiple antennas according to some embodiments. eNB 602 has multiple antennas, as depicted, which may be used in various groupings, and with various signal modifications for each grouping, to effectively produce a plurality of antenna ports P1-P4. In various embodiments within the framework of the illustrated example, each antenna port P1-P4 may be defined for 1, 2, 3, or 4 antennas. Each antenna port P1-P4 may correspond to a different transmission signal direction. Using the different antenna ports, eNB 602 may transmit multiple layers with codebook-based or non-codebook-based preceding techniques. According to some embodiments, each antenna port corresponds to a beam antenna port-specific CSI-RS signals are transmitted at via respective antenna port. In other embodiments, there may be more, or fewer, antenna ports available at the eNB than the four antenna ports as illustrated in FIG. 6.

[0073] On the UE side, there are a plurality of receive antennas. As illustrated in the example of FIG. 6, there four receive antennas, A1-A4. The multiple receive antennas may be used selectively to create receive beam forming. Receive beam forming may be used advantageously to increase the receive antenna gain for the direction(s) on which desired signals are received, and to suppress interference from neighboring cells, provided of course that the interference is received along different directions than the desired signals.

[0074] In various embodiments, beamforming, beam selection, and MUVfO operations may be performed at eNB 300 by processing circuitry 306, transceiver circuitry 30S, or some combination of these facilities. Likewise, in various embodiments, the beamforming, beam selection, and MUVfO operations may be performed at UE 200 by application circuitry 202, baseband circuitry 204, Radio Frequency (RF) circuitry 206, or some combination of these facilities. In related embodiments, certain beam selection operations may be performed using distributed computing techniques, where certain information storage or processing operations are handled with the assistance of an external device, such as eNB 300, UE 200, or system 400.

[0075] Beamforming is a technique used in wireless communications for directional signal transmission and/or reception. It combines elements in a phased array in a way to coastructively interfere with signals at certain angles while other angles experience destructive interference. In this manner, beamforming may concentrate a signal to a target location, e.g. the UE's location. The improvement compared with omnidirectional reception/transmission is known as the gain (or loss in the case of diminishment). Hybrid beamforming implements a digital unit with antenna ports processing digital signals and an analog beamforming unit with antenna elements processing analog signals. Each antenna port is connected to a subarray of several antenna elements and receives a digital signal filtered by the analog beamforming.

[0076] FIG. 7 is a diagram illustrating an exemplary communication network scenario in an aspect of this disclosure. In this scenario, a single beamforming direction and its corresponding beamforming area of the overall beamforming pattern will be discussed. It should be appreciated that the communication network scenario is exemplary in nature and thus may be simplified for purposes of this explanation.

[0077] E-node B 720 provides coverage to cell 710 and serves UEs in the coverage area by hybrid beamforming. In the structure of hybrid beamforming, there are N antenna ports (n= 1, 2, ..., N) at the base station eNB and each antenna port is connected to a subarray of M antenna elements (m= 1, 2, ..., M). Each antenna element has a phase shifter controlled by the analog beamforming parameters, such as beamforming weights. In this respect, each antenna port is connected to a phased array of antenna elements in which the relative phases of the respective signals feeding the antenna elements are set in such a way that each antenna port's effective beamforming radiation pattern is reinforced in a desired direction and suppressed in undesired directions.

[0078] Broadside 7S0 is the line from which locations (i.e. angles) in relation to the base station are measured from Accordingly, the mobile terminal's 730 relative location to the base station 720 is the channel direction information (COT). The base station 720 may configured to form the beam towards the channel direction information, i.e. towards the channel.

[0079] Beamforming in the context of the present disclosure means beam steering towards a direction 740A of eNB antenna port n (not pictured) are at angle θη 740C as well as beam shaping, i.e. beam broadening corresponding to beamforming area 740B. It is appreciated that beamforming direction 740 A is just one or a plurality of beamforming directions (and beamforming areas, e.g. 740B) which help to form the overall beamforming pattern from base station 720. It will also be appreciated that the main beam (or main lobe) of beamforming area 740 B is depicted in FIG. 7, but beamforming area 740B may also include sidelobes.

[0080] FIG. 8 shows an example hybrid beamforming system architecture 800, e.g. at a base station, in an aspect of this disclosure. It is appreciated that system architecture 800 is exemplary in nature and may thus be simplified for purposes of this explanation. The hybrid beamfoiming system architecture 800 includes a transmitter side 818, a radio channel 817 and a receiver side 819.

[0081] The digital domain of the transmitter side 818 includes a MIMO encoder

801 and a baseband pre-coder 802 that generates a plurality of digital baseband signals 803.1 - 803. N, wherein the index following the dot in the reference indicates the antenna port over which the signal is to be transmitted.

[0082] Digital-to-analog converters 804.1 -804.N convert the digital baseband signals 803.1-803.N to analog baseband signals. The analog domain of the transmitter side 818 includes a plurality of RF-chains.

[0083] The first RF-chain includes mixer 80S.1, a plurality of phase shifters 806.1 and antenna (sub)-array 807.1 that generates a beam 815.1, wherein the beam 815.1 is shown for a plurality of exemplary beam forming directions.

[0084] The N^th RF-chain includes mixer 805.N, a plurality of phase shifters 806.N and antenna (sub)-array 807.N that generates beam 815.N, wherein beam 815.N is shown for a plurality of exemplary beam forming directions.

[0085] Regarding the first RF-chain, mixer 805.1 converts the analog baseband signal to an analog radio frequency (RF) signal. Each phase shifter of the plurality of phase shifters 806.1 shifts the phase of the RF signal and feeds the shifted RF signal to its corresponding antenna element of the antenna array 807.1. Depending on the analog beam forming parameters, such as weights, e.g. phase shift, of a phase shifter the beam 815.1 can be steered to a selected beamforming direction. The chain operates in a corresponding way. The phase shifts of the plurality of phase shifters 806.N may differ from the phase shifts of the plurality of phase shifters of any preceding chain, e.g. chain N-l, N-2, up to chain 1, to generate a beam 815.N in a direction that differs from the direction of a beam of any preceding chain, e.g. the direction of beam 815.1

[0086] The beams of the first chain to the N* chain may be steered to compensate the path loss in the mm Wave band. When applying MIMO techniques, e.g. spatial multiplexing, each antenna port 1 up to n may be a MIMO port. Antenna array 807.1 may transmit a radio signal over radio channel 817 indicated by the dotted octagon. The radio signal may be received by each antenna array 808.1 - 808.N of receiver side 819. Each antenna array of antenna arrays 807.1 - 807.N may transmit a radio signal. Each antenna array 808.1 - 808.N of the receiver side 819 may receive a superposition of radio signals transmitted from each of the antenna arrays 807.1 -

807. N of the transmitter side 818.

[0087] The first RF-chain of the receiver side 819 includes antenna array 808.1, a plurality of phase shifters 809.1. Each phase shifter of the plurality of phase shifters is coupled to a corresponding antenna element of antenna array 808.1 and a mixer 810.1. Each phase shifter of the plurality of phase shifters 809.1 shifts the phase of the receive RF-signal of its corresponding antenna element of antenna array 808.1. Mixer 810.1 down-mixes combined shifted RF-signals of each antenna element of antenna array 808.1 to baseband. Analog-to-digital converter 811.1 converts the analog baseband signal to digital domain and feeds it to antenna port 812.1.

[0088] The Ν^th chain of the receiver side 819 includes antenna array 808.N, a plurality of phase shifters 809.N, wherein each phase shifter of the plurality of phase shifters is coupled to a corresponding antenna element of antenna array 808.N and a mixer 810.N. Each phase shifter of the plurality of phase shifters 809.N shifts the phase of the receive RF-signal of its corresponding antenna element of antenna array

808. N. Mixer 810.N down-mixes combined shifted RF-signals of each antenna element of antenna array 808.N to baseband. Analog-to-digital converter 811.N converts the analog baseband signal to digital domain and feeds it to antenna port 812.N.

[0089] Basedband combiner 813 combines the digital baseband signals 812.1 up to 812.N and MIMO decoder performs MEMO decoding on the combined baseband signals.

[0090] In mmWave channels, high beamforming (BF) gain is used to compensate for large path loss. To achieve high BF gain, a large number of antenna elements is generally used. In conventional digital BF architecture, the use of many antenna elements results in correspondingly large quantity of RF chains, and analog to digital/digital to analog converters (ADC/DAC) which tend to consume large amounts of power, and add to the complexity and cost of the hardware.

[0091] Hybrid BF architecture, such as the example illustrated and described above with reference to FIG. 8 has been proposed as a practical solution to implement massive MIMO for mm Wave channels. The received signal at the kth user (UE) may be expressed as:

where:

N_b : Number of RF chains at the eNB or other type of base station (BS); N_m: Number of RF chains at UE;

w_BSi is a (n_RF x 1) vector and vector, where n_RF is the

number of elements in each RF chain;

θ_i can be the same or different for every RF chain depending on the use case.

P_MSk is a N_Sk x N_m digital receive BF circuitry at user k;

P_BS is an N_b x N_s digital precoder circuitry at the BS where each column,

(P_BSk), corresponds to the digital BF vector for a given user and stream;

N_Sk is number of symbols transmitted to user k; and

N_s is total number of transmitted symbols.

[0092] In a multiuser scenario with U users,

[0093] A hybrid BF arrangement may include two components, analog BF processing, and digital BF processing. In the analog section, user and beam acquisition is performed by way of a sector sweep procedure. Analog BF parameters (e.g., weights) may be defined for all users: . In the

digital section, digital BF parameters (e.g. weights) are defined, and multi user scheduling uses knowledge of the channel for all UEs. From equation (1) above, knowledge of " is needed for every user. Some of the challenges

associated with this stage compared to conventional digital BF may be explained as follows. In conventional digital BF architectures (where there is no analog BF), the received signal for user k is:

[0094] Channel measurements are performed through transmission of cell-specific reference signals. In TDD modulation embodiments, all the UEs transmit sounding reference signals (SRS) and the BS measures the channels. In FDD modulation embodiments, channel-state-information reference signals (CSI-RS) are transmitted from all antennas and every UE is able to measure the channel and send feedback to the BS. Conventionally, all transmission and reception is implemented with omnidirectional antennas. However, in a hybrid BP architecture, as can be seen from equation (1), the directional channel

for every user is to be measured. Therefore, transmission of either SRS or CSI-RS is UE-specific and must be beam-formed to each UE. In mmWave systems, both,

are set on the direction of user k. As a result, channel measurements for different users are done in sequential, TDMA-like fashion, which causes longer delays experienced by users as latency.

[0095] Moreover, in multiuser (MU) hybrid BF systems, the effective channels for UEs are different than what is measured during the initial channel quality

assessment, where all RF chains transmit in the same direction. For instance, having 4 users for a BS with 8 RF chains, every 2 RF chains transmit in a different direction. After initial channel measurements and MU scheduling,

in equation (1) is a function of the selected paired UEs. In equation can be all in the same

direction or U different directions. Therefore after selecting the paired UEs and adjusting W_BS accordingly, the channels for paired UEs are to be sounded again.

[0096] Accordingly, MU scheduling and digital BF calculations should generally be performed based on the effective directional channel for every UE. However, per- UE channel measurement, as explained above, are not practical for MU digital BF arrangements.

[0097] Aspects of the present disclosure include various solutions for the aforementioned challenges, though it will be appreciated that the solutioas may also find application in related types of systems that may present other types of challenges. FIG. 9A is a process flow diagram illustrating an example set of high- level operations to be performed by an eNB or base station (BS) that supports hybrid beamforming (BF) according to some embodiments.

[0098] At 902 a UE/Beam acquisition procedure is performed using a sector sweep operation, which identifies angles of departure (AOD) for signal transmissions to be directed to each of the UEs. As a result, the analog BF weights may be defined for each of the UEs. A preliminary user scheduling is performed based on

the W_BS (k), W_MSk analog BF weights that resulted from UE/RF Beam acquisition operations of the sector sweep, subsequently, directional channel measurements, MIMO mode selection, user scheduling refinement and digital BF calculations may all be performed as follows. At 904, a subset of UEs is selected, using analog BF, for channel quality assessment (CQA), which is described in greater detail below. At 906, digital channel quality assessment is performed on individual ones of the subset of UEs, from which MIMO mode selection and user scheduling refinement, among other possible operations, may be performed. Advantageously, the selection of the subset of UEs provides improved overall efficiency in the management of hybrid-BF BS operation.

[0099] FIG. 9B is a flow diagram illustrating example operations that are included in the selection of the subset of UEs for CQA assessment of operation 904 according to an example embodiment. At 910, a signal quality measure, such as signal-to-noise ratio (SNR), signal to interference noise ratio (SINR), or the like, is collected for each UE. At 912, the UEs having the best signal quality measures are selected. At 914, additional criteria requiring a minimum difference in angle of departure (AOD) for the selected UEs is applied to filter UEs positioned at similar angles from the BS. If the AOD between two selected UEs is greater than a predefined threshold, the UEs may be selected for multi-user (MU) MIMO operation.

[0100] For instance, where the AOD filter criteria may be

expressed as: (with δ or

Θ being a design parameter).

[0101] At 906, the selected subset of UEs may be instructed for CQA signaling, such as uplink sounding signaling or CSI-RS feedback signaling. FIGs. 9C and 9D illustrate various embodiments for carrying out operations 906. Referring first to FIG. 9C, at 920, the analog BF weights at the BS are adjusted according to AOD of the UEs selected at 904. At 922, the effective analog beam-formed channel is measured for all selected UEs. At 924, digital BF weights (e.g., using a zero-forcing MU BF technique, or another suitable technique) are calculated based on the channel measurements. This process may be completed in one symbol and the BS may perform it by scheduling sector-specific CSI-RS/ feedback or sector-specific UL sounding as suitable techniques for collecting CQA information.

[0102] In the approach of FIG. 9D, the BS relies on channel measurements (e.g., analog beam-formed channel) for all UEs selected at 904 for further scheduling refinement as well as MIMO mode selection. At 926, the BS allocates K symbols for CQA (e.g., sector-specific UL sounding or CSI-RS transmission), where K is the number of candidate sectors from which UEs are selected. At 928, the effective channels for all selected UEs and for all candidate transmit sectors are measured. At 930, the digital BF weights are computed to facilitate MIMO mode selection, MU pairing and digital BF optimization to maximize the sum throughput

[0103] FIGs. lOA-lOC are time-frequency diagrams illustrating example use cases in which the process of FIG.9 A is applied in a system that utilizes frequency division multiplexing (FDM) to multiplex CQA signaling (e.g., CSI-RS, or UL sounding) transmitted from different antenna ports in the frequency domain. In the examples depicted, the BS has 8 RF chains, as indicated with numerals 1-8 in the blocks.

[0104] In the example of FIG. 10A, the BS multiplexes CQA signaling for different RF chains/antenna ports in the frequency domain. Thus, the CQA signaling may be beam-formed in different directions and transmitted simultaneously for UEs to measure the channels and provide feedback or sounding accordingly. In

embodiments using OFDM modulation, this operation may be implemented by allocating orthogonal sub-bands to different RF chains. In SC modulation embodiments, IFDM may be used for frequency multiplexing of CQA signaling in different RF chains.

[0105] As illustrated in FIG. 10A, two UEs are selected to be paired at operation 904. The UEs are situated in sectors 1002A and 1002B (as seen by the BS). Here, four RF chains (1-4) are allocated to one UE of the pair to steer beams to that UE, while the remaining four (5-8) are allocated to the other UE. Each set of RF chains transmits CQA signaling simultaneously using one symbol period as shown.

[0106] FIG. 10B illustrates another use case where the selected UEs for MU grouping are distributed in 4 sectors, 1012-1018. In this example, there may be four UEs in the four sectors, or four sets of UEs, with each set in one of the four sectors. As depicted, four symbols are used to transmit CQA signaling such as CSI-RS or UL sounding iastructions to each set of UEs. All 8 RF chains are used to send the CQA signaling, sequentially, to each of the four sector in which UEs have been selected. Based on the responses to the CQA signaling received from the UEs, further channel optimization may be performed, and individual UEs may be selected for MU-MIMO operation. [0107] FIG. IOC illustrates a combined embodiment in which the first symbol period combines CQA signaling to two different sectors, 1022A and 1022B, with RF chains 1-4 directing the transmissions to one sector and RF chains 5-8 directing the transmissions to the other sector as in the example of FIG. 10A; and the subsequent two symbols used to send CQA signaling to individual sectors using all eight RF chains for CQA signaling transmission to sectors 1024 and 1026.

[0108] In some embodiments, two-layer codebook is used for analog beamforming, with the first layer used to generate wider beams, and the second layer to generate narrower beams. In various embodiments, the sector/beam may be from the first layer or the second layer. In particular, in the case of there being large numbers of elements in every RF chain, the wider beams of the first layer may be used for the purpose of initial sector-specific measurements, as will be described in greater detail below.

[0109] According to one aspect of the embodiments, a sector-specific preliminary CQA is performed before the UE selections of operation 904 (FIG.9) are made. FIG. 11 is a flow diagram illustrating an example process utilizing a preliminary sector- specific CQA according to some embodiments.

[0110] At 1102, the BS performs a sector sweep operation. At 1104, the BS groups UEs based on assessed angle of departure (AOD). At 1106, the UEs are grouped according to their best-assessed transmit sector. At 1108, for each group (same sector), the BS schedules UEs to send their CQA signaling, which maybe sounding signaling or CSI-RS feedback signaling as discussed above. In an embodiment, the UEs in each sector are instructed to send their CQA signaling at the same time. The UEs in different groups may be time-multiplexed to send their CQA signaling. The UEs that send CQA signaling at the same time may need to use orthogonal reference sequences.

[0111] At 1110, the directional channels are measured for all UEs:

At 1112, MIMO mode and digital beamforming weights are calculated for every individual UE accordingly (e.g. Eigen BF and zero forcing (ZF) for MU-BF in multiuser pairing):

[0112] As a result of these computations, at 1114, a candidate set of UEs for MU pairing is selected from the strongest UEs (e.g., based on received SNR) which are angularly separated by a suitable extent to avoid mutual interference. For instance, the AOD filter criteria may be defined for or

equivalently,

_j (where δ or Θ is a predefined parameters).

[0113] At 1116, the BS calculates the sum throughput resulting from addition of UEs to a MU set. At 1118, UEs are added to the ML! set from the candidate set of UEs, and the sum throughput is rechecked at 1116 until the sum throughput is no longer increased by the addition of a candidate UE.

[0114] To calculate sum throughput at 1116 according to an example, the transmit power may be scaled based on the number of paired UEs. The received power for every UE is calculated based on one UE transmission with digital BF. The inter-UI interference for pairing U (quantity) of UIs is calculated as the interference power for the

where

[0115] At 1120, aperiodic "on-demand" CQA is scheduled only for the UEs to be MU-paired. The selected UEs to be paired for MU BF are instructed concurrently for the one-shot CQA.

[0116] At 1122, the analog BF weights at the BS are set according to the AOD of selected paired UEs. At 1124, the effective analog beam-formed channel is measured for all paired UEs of the MU sets. At 1126, digital BF weights (e.g., zero forcing MU BF) are finalized based on the channel measurements.

[0117] In a related embodiment, where CSI-RS transmission and UE feedback is used for the CQA, the UEs in the same sector/beam are scheduled at 1108 for CSI- RS transmission and codebook feedback. The directional channels are measured at the UEs and quantized digital BF vectors (or precoding matrix indicators PMI) as well as CQI are feedback are sent to the BS as: p_BSl, ... , Pes_k · CQv— CQK · To calculate sum throughput at 1116 for the CSI-RS-specific embodiments, interference power for i^thuser is defined as

The selected UEs to be paired for MU BP are scheduled for one time CS1-RS transmission and feedback at 1120. Accordingly, CSI-RS are transmitted beam- formed from every RF chain according to the selected UEs AOD.

[0118] For example for a BS that has 8 RF chains and where 4 UEs are selected at angles:

, CSI-RS are transmitted from 8 RF chaias, every 2 RF chains beam-formed at the same direction. The UEs measure their channels, calculate quantized digital BF vector and send feedback to the BS, which obtains the measurements at 1124. The BS performs MU zero-forcing beamforming on the received feedback at 1126.

[0119] Additional notes and examples:

[0120] Example 1 is apparatus of radio access network (RAN) base station configurable for hybrid beam-forming (BF) radio communications with a set of user equipment (UEs) within a service area, the apparatus comprising: memory, and processing circuitry to: configure the base station to perform a sector-sweep operation to identify analog beam-forming (BF) parameters for individual ones of the set of UEs within the service area; select a first subset of UEs from among the set of UEs, the first subset of UEs being selected based on a first set of BF sector membership attributes determined in the sector-sweep operation, the first subset of UEs to be subject to concurrent channel quality assessment (CQA); encode signaling for transmission to individual ones of the UEs of the first subset to configure those UEs to transmit CQA signaling, the CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters; and decode CQA signaling from the UEs of the first subset to determine digital BF parameters for use with the hybrid BF radio communications.

[0121] In Example 2, the subject matter of Example 1 optionally includes wherein the analog BF parameters are analog BF weights.

[0122] In Example 3, the subject matter of any one or more of Examples 1-2 optionally include wherein the first subset is selected based on a combination of signal-to-noise measurement and angle-of-departure information for individual ones of the UEs of the service area obtained during the sector sweep operation.

[0123] In Example 4, the subject matter of any one or more of Examples 1 -3 optionally include wherein the first subset is selected based on a sector-specific preliminary CQA, wherein in response to the sector-sweep operation the UEs within the service area are grouped according to sector, and wherein the processing circuitry is to further encode signaling for transmission to UEs of each sector-group to configure those UEs to UEs to transmit first subset-specific CQA signaling concurrently.

[0124] In Example S, the subject matter of Example 4 optionally includes wherein the processing circuitry is to further select a second subset of UEs from among the set of UEs, the second subset of UEs being selected based on a second set of BF sector membership attributes determined in the sector-sweep operation, the second subset of UEs to be subject to concurrent channel quality assessment (CQA) at a different symbol time than the CQA for the first subset; encode signaling for transmission to individual ones of the UEs of the second subset to configure those UEs to transmit second subset-specific CQA signaling , the second subset-specific CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters.

[0125] In Example 6, the subject matter of any one or more of Examples 4-5 optionally include wherein the first subset is selected further based on signal measurement of analog and digital BF-configured channels in response to the preliminary CQA.

[0126] In Example 7, the subject matter of any one or more of Examples 4-6 optionally include wherein the preliminary CQA is performed periodically.

[0127] In Example 8, the subject matter of any one or more of Examples 1-7 optionally include wherein the CQA signaling includes uplink sounding signaling.

[0128] In Example 9, the subject matter of any one or more of Examples 1-8 optionally include wherein the CQA signaling includes channel state information- reference signaling (CSI-RS).

[0129] In Example 10, the subject matter of any one or more of Examples 1-9 optionally include wherein the processing circuitry is to further perform:

configuration of multi-user (MU) multiple input-multiple output (MIMO) parameters in response to computation of digital BF parameters for the UEs of the first subset.

[0130] In Example 11 , the subject matter of Example 10 optionally incl udes wherein configuration of the MIMO parameters is based on incremental sum- throughput addition of MU-member UEs.

[0131] In Example 12, the subject matter of any one or more of Examples 10-11 optionally include wherein the processing circuitry is to further : instruct MU- configured UEs of the first subset to transmit on-demand CQA signaling; and adjust of digital BF parameters for the UEs of the first subset in response to the on-demand CQA signaling.

[0132] In Example 13, the subject matter of Example 12 optionally includes wherein the on-demand CQA signaling is to be transmitted concurrently by the MU- configured UEs.

[0133] In Example 14, the subject matter of any one or more of Examples 1-13 optionally include wherein the processing circuitry is to further perform multi-layer analog BF including use of a first layer to produce relatively wide beams, and use of a second layer to produce relatively narrow beams.

[0134] In Example 15 , the subject matter of any one or more of Examples 1-14 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is frequency-multiplexed to UEs in different sectors.

[0135] In Example 16, the subject matter of any one or more of Examples 1—15 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is completed using one symbol.

[0136] In Example 17, the subject matter of any one or more of Examples 1-16 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is time-multiplexed by sector in which the UEs are located.

[0137] In Example 18, the subject matter of any one or more of Examples 1-17 optionally include radio frequency (RF) transceiver circuitry including a plurality of RF chains; and a plurality of antenna elements operatively coupled to the RF transceiver circuitry.

[0138] In Example 19, the subject matter of any one or more of Examples 1-18 optionally include wherein the memory and processing circuitry are part of an evolved node-B.

[0139] Example 20 is apparatus of user equipment (UE) configurable for hybrid beam-forming (BF) radio communications with a base station (BS) within a service area of a radio access network (RAN), the apparatus comprising: memory; and processing circuitry to respond to a BS transmit sector sweep operation to facilitate assessment of BS transmit beam direction specific to the UE, decode signaling from the BS instructing the UE to send channel quality assessment (CQA) signaling, wherein the CQA signaling represents channel performance of respective channels that are established by the BS, encode the CQA signaling for transmission to the BS concurrently with a group of other UE devices, wherein membership in the group is determined in response to a BS sector sweep operation based on a combination of signal-to-noise measurement and angle-of-departure information corresponding to UEs in the service area obtained during the sector sweep operation.

[0140] In Example 21 , the subject matter of Example 20 optionally includes wherein membership in the group is determined based on a sector-specific preliminary CQA, wherein in response to the sector-sweep operation the UEs within the service area are grouped according to sector.

[0141] In Example 22, the subject matter of Example 21 optionally includes wherein the processing circuitry is to cause the UE to perform signal measurement of analog and digital BF-configured channels.

[0142] In Example 23 , the subject matter of any one or more of Examples 21-22 optionally include wherein the processing circuitry receives instructions to encode the CQA periodically.

[0143] In Example 24, the subject matter of Example 23 optionally includes wherein the processing circuitry is to receive and carry out multi-user multiple input/multiple output (MU-MIMO) instructions to transmit aperiodic CQA signaling.

[0144] In Example 25 , the subject matter of any one or more of Examples 20-24 optionally include wherein the CQA signaling includes uplink sounding signaling.

[0145] In Example 26, the subject matter of any one or more of Examples 20-25 optionally include wherein the CQA signaling includes channel state information- reference signaling (CSI-RS).

[0146] In Example 27, the subject matter of any one or more of Examples 24-26 optionally include wherein the on-demand CQA signaling is to be transmitted concurrently by the UE, along with other UEs configured in a MU-paired relationship with the UE.

[0147] In Example 28, the subject matter of any one or more of Examples 20-27 optionally include wherein the apparatus is to cause the UE to transmit CQA signaling using only one symbol.

[0148] In Example 29, the subject matter of any one or more of Examples 20-28 optionally include radio frequency (RF) transceiver circuitry including a plurality of RF chains; and a plurality of antenna elements operatively coupled to the RF transceiver circuitry.

[0149] Example 30 is at least one machine-readable medium containing instructions that, when executed on a processor of a radio access network (RAN) base station configurable for hybrid beam- forming (BF) radio communications with a set of user equipment (UEs) within a service area, cause the processor to: configure the base station to perform a sector-sweep operation to identify analog beam-forming (BF) parameters for individual ones of the set of UEs within the service area; select a first subset of UEs from among the set of UEs, the first subset of UEs being selected based on a first set of BF sector membership attributes determined in the sector- sweep operation, the first subset of UEs to be subject to concurrent channel quality assessment (CQA); encode signaling for transmission to individual ones of the UEs of the first subset to configure those UEs to transmit CQA signaling, the CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters; and decode CQA signaling from the UEs of the first subset to determine digital BF parameters for use with the hybrid BF radio communications.

[0150] In Example 31 , the subject matter of Example 30 optionally incl udes wherein the analog BF parameters are analog BF weights.

[0151] In Example 32, the subject matter of any one or more of Examples 30-31 optionally include wherein the first subset is selected based on a combination of signal-to-noise measurement and angle-of-departure information for individual ones of the UEs of the service area obtained during the sector sweep operation.

[0152] In Example 33, the subject matter of any one or more of Examples 30-32 optionally include wherein the first subset is selected based on a sector-specific preliminary CQA, wherein in response to the sector-sweep operation the UEs within the service area are grouped according to sector, and wherein the processing circuitry is to further encode signaling for transmission to UEs of each sector-group to configure those UEs to UEs to transmit first subset-specific CQA signaling concurrently.

[0153] In Example 34, the subject matter of Example 33 optionally includes wherein the instructions are to cause the processor to further select a second subset of UEs from among the set of UEs, the second subset of UEs being selected based on a second set of BF sector membership attributes determined in the sector-sweep operation, the second subset of UEs to be subject to concurrent channel quality assessment (CQA) at a different symbol time than the CQA for the first subset; and encode signaling for transmission to individual ones of the UEs of the second subset to configure those UEs to transmit second subset-specific CQA signaling , the second subset-specific CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters.

[0154] In Example 35 , the subject matter of any one or more of Examples 33-34 optionally include wherein the first subset is selected further based on signal measurement of analog and digital BF-configured channels in response to the preliminary CQA.

[0155] In Example 36, the subject matter of any one or more of Examples 33-35 optionally include wherein the preliminary CQA is performed periodically.

[0156] In Example 37, the subject matter of any one or more of Examples 30-36 optionally include wherein the CQA signaling includes uplink sounding signaling.

[0157] In Example 38, the subject matter of any one or more of Examples 30-37 optionally include wherein the CQA signaling includes channel state information- reference signaling (CSI-RS).

[0158] In Example 39, the subject matter of any one or more of Examples 30-38 optionally include wherein the instructions are to cause the processor to: configure multi-user (MU) multiple input-multiple output (MIMO) parameters in response to computation of digital BF parameters for the UEs of the first subset.

[0159] In Example 40, the subject matter of Example 39 optionally includes wherein configuration of the MIMO parameters is based on incremental sum- throughput addition of MU-member UEs.

[0160] In Example 41 , the subject matter of any one or more of Examples 39-40 optionally include wherein the instructions are to cause the processor to: encode instructions to MU-configured UEs of the first subset to transmit on-demand CQA signaling; and adjust digital BF parameters corresponding to the UEs of the first subset in response to the on-demand CQA signaling.

[0161] In Example 42, the subject matter of Example 41 optionally includes wherein the on-demand CQA signaling is to be transmitted concurrently by the MU- configured UEs.

[0162] In Example 43 , the subject matter of any one or more of Examples 30-42 optionally include wherein the instructions are to cause the processor to control multi-layer analog BF including a first layer to produce relatively wide beams, and a second layer to produce relatively narrow beams. [0163] In Example 44, the subject matter of any one or more of Examples 30-43 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is frequency-multiplexed to UEs in different sectors.

[0164] In Example 45 , the subject matter of any one or more of Examples 30-44 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is completed using one symbol.

[0165] In Example 46, the subject matter of any one or more of Examples 30-45 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is time-multiplexed by sector in which the UEs are located.

[0166] Example 47 is a radio access network (RAN) base station configurable for hybrid beam-forming (BF) radio communications with a set of user equipment (UEs) within a service area, the system comprising: means for configuring the base station to perform a sector-sweep operation to identify analog beam-forming (BF) parameters for individual ones of the set of UEs within the service area; means for selecting a first subset of UEs from among the set of UEs, the first subset of UEs being selected based on a first set of BF sector membership attributes determined in the sector-sweep operation, the first subset of UEs to be subject to concurrent channel quality assessment (CQA); means for encoding signaling for transmission to individual ones of the UEs of the first subset to configure those UEs to transmit CQA signaling, the CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters; and means for decoding CQA signaling from the UEs of the first subset to determine digital BF parameters for use with the hybrid BF radio communications.

[0167] In Example 48, the subject matter of Example 47 optionally includes wherein the analog BF parameters are analog BF weights.

[0168] In Example 49, the subject matter of any one or more of Examples 47-48 optionally include wherein the first subset is selected based on a combination of signal-to-noise measurement and angle-of-departure information for individual ones of the UEs of the service area obtained during the sector sweep operation.

[0169] In Example 50, the subject matter of any one or more of Examples 47-49 optionally include wherein the first subset is selected based on a sector-specific preliminary CQA, wherein in response to the sector-sweep operation the UEs within the service area are grouped according to sector, and wherein the processing circuitry is to further encode signaling for transmission to UEs of each sector-group to configure those UEs to UEs to transmit first subset-specific CQA signaling concurrently.

[0170] In Example 51 , the subject matter of Example 50 optionally includes means for selecting a second subset of UEs from among the set of UEs, the second subset of UEs being selected based on a second set of BF sector membership attributes determined in the sector-sweep operation, the second subset of UEs to be subject to concurrent channel quality assessment (CQA) at a different symbol time than the CQA for the first subset; and means for encoding signaling for transmission to individual ones of the UEs of the second subset to configure those UEs to transmit second subset-specific CQA signaling , the second subset-specific CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters.

[0171] In Example 52, the subject matter of any one or more of Examples 50-51 optionally include wherein the first subset is selected further based on signal measurement of analog and digital BF-configured channels in response to the preliminary CQA.

[0172] In Example 53, the subject matter of any one or more of Examples 50-52 optionally include wherein the preliminary CQA is performed periodically.

[0173] In Example 54, the subject matter of any one or more of Examples 47-53 optionally include wherein the CQA signaling includes uplink sounding signaling.

[0174] In Example 55 , the subject matter of any one or more of Examples 47-54 optionally include wherein the CQA signaling includes channel state information- reference signaling (CSI-RS).

[0175] In Example 56, the subject matter of any one or more of Examples 47-55 optionally include means for configuring multi-user (MU) multiple input-multiple output (ΜΓΜΟ) parameters in response to computation of digital BF parameters for the UEs of the first subset.

[0176] In Example 57, the subject matter of Example 56 optionally includes wherein configuration of the MIMO parameters is based on incremental sum- throughput addition of MU-member UEs.

[0177] In Example 58, the subject matter of any one or more of Examples 56-57 optionally include means for instructing MU-configured UEs of the first subset to transmit on-demand CQA signaling; and means for adjusting digital BF parameters for the UEs of the first subset in response to the on-demand CQA signaling. [0178] In Example 59, the subject matter of Example 58 optionally includes wherein the on-demand CQA signaling is to be transmitted concurrently by the MU- configured UEs.

[0179] In Example 60, the subject matter of any one or more of Examples 47-59 optionally include means for multi-layer analog BF including use of a first layer to produce relatively wide beams, and use of a second layer to produce relatively narrow beams.

[0180] In Example 61 , the subject matter of any one or more of Examples 47-60 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is frequency-multiplexed to UEs in different sectors.

[0181] In Example 62, the subject matter of any one or more of Examples 47-61 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is completed using one symbol.

[0182] In Example 63 , the subject matter of any one or more of Examples 47-62 optionally include wherein the configuration of the UEs of the first subset to transmit CQA signaling is time-multiplexed by sector in which the UEs are located.

[0183] In Example 64, the subject matter of any one or more of Examples 47-63 optionally include radio frequency (RF) transceiver circuitry including a plurality of RF chains; and a plurality of antenna elements operatively coupled to the RF transceiver circuitry.

[0184] In Example 65 , the subject matter of any one or more of Examples 47-64 optionally include wherein the memory and processing circuitry are part of an evolved node-B.

[0185] The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments that may be practiced. These embodiments are also referred to herein as "examples." Such examples may include elements in addition to those shown or described. However, also contemplated are examples that include the elements shown or described. Moreover, also contemplated are examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein. [0186] Publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) are supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0187] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a nonexclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In the appended claims, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to suggest a numerical order for their objects.

[0188] The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with others. Other embodiments may be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. However, the claims may not set forth every feature disclosed herein as embodiments may feature a subset of said features. Further, embodiments may include fewer features than those disclosed in a particular example. Thus, the following claims are hereby incorporated into the Detailed Description, with a claim standing on its own as a separate embodiment. The scope of the embodiments disclosed herein is to be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

CLAIMS What is claimed is:

1. Apparatus of radio access network (RAN) base station configurable for hybrid beam-forming (BF) radio communications with a set of user equipment (UEs) within a service area, the apparatus comprising:

memory; and

processing circuitry to:

configure the base station to perform a sector-sweep operation to identify analog beam-forming (BF) parameters for individual ones of the set of UEs within the service area;

select a first subset of UEs from among the set of UEs, the first subset of UEs being selected based on a first set of BF sector membership attributes determined in the sector-sweep operation, the first subset of UEs to be subject to concurrent channel quality assessment (CQA);

encode signaling for transmission to individual ones of the UEs of the first subset to configure those UEs to transmit CQA signaling, the CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters; and

decode CQA signaling from the UEs of the first subset to determine digital BF parameters for use with the hybrid BF radio communicatioas.

2. The apparatus of claim 1, wherein the first subset is selected based on a combination of signal-to-noise measurement and angle-of-departure information for individual ones of the UEs of the service area obtained during the sector sweep operation.

3. The apparatus of claim 1, wherein the first subset is selected based on a sector-specific preliminary CQA, wherein in response to the sector-sweep operation the UEs within the service area are grouped according to sector, and wherein the processing circuitry is to further encode signaling for transmission to UEs of each sector-group to configure those UEs to UEs to transmit first subset-specific CQA signaling concurrently.

4. The apparatus of claim 3, wherein the processing circuitry is to further select a second subset of UEs from among the set of UEs, the second subset of UEs being selected based on a second set of BF sector membership attributes determined in the sector-sweep operation, the second subset of UEs to be subject to concurrent channel quality assessment (CQA) at a different symbol time than the CQA for the first subset;

encode signaling for transmission to individual ones of the UEs of the second subset to configure those UEs to transmit second subset-specific CQA signaling , the second subset-specific CQA signaling representing channel performance of respective channels that are established based on the analog BF parameters.

5. The apparatus of claim 3, wherein the first subset is selected further based on signal measurement of analog and digital BF-configured channels in response to the preliminary CQA.

6. The apparatus of claim 3, wherein the preliminary CQA is performed periodically.

7. The apparatus according to any preceding claim, wherein the processing circuitry is to further perform:

8. The apparatus of claim 7, wherein the processing circuitry is to further : instruct MU-configured UEs of the first subset to transmit on-demand CQA signaling; and

adjust of digital BF parameters for the UEs of the first subset in response to the on-demand CQA signaling.

9. The apparatus of claim 8, wherein the on-demand CQA signaling is to be transmitted concurrently by the MU-configured UEs.

10. The apparatus according to any one of claims 1-6, wherein the configuration of the UEs of the first subset to transmit CQA signaling is frequency-multiplexed to UEs in different sectors.

11. The apparatus according to any one of claims 1-6, wherein the configuration of the UEs of the first subset to transmit CQA signaling is completed using one symbol.

12. The apparatus according to any one of claims 1 -6, wherein the configuration of the UEs of the first subset to transmit CQA signaling is time-multiplexed by sector in which the UEs are located.

13. The apparatus according to any one of claims 1-6, further comprising:

radio frequency (RF) transceiver circuitry including a plurality of RF chains; and

a plurality of antenna elements operatively coupled to the RF transceiver circuitry.

14. The apparatus according to any one of claims 1 -6, wherein the memory and processing circuitry are part of an evolved node-B.

15. Apparatus of user equipment (UE) configurable for hybrid beam-forming (BF) radio communications with a base station (BS) within a service area of a radio access network (RAN), the apparatus comprising:

memory, and

processing circuitry to:

respond to a BS transmit sector sweep operation to facilitate assessment of BS transmit beam direction specific to the UE;

decode signaling from the BS instructing the UE to send channel quality assessment (CQA) signaling, wherein the CQA signaling represents channel performance of respective channels that are established by the BS; and

encode the CQA signaling for transmission to the BS concurrently with a group of other UE devices, wherein membership in the group is determined in response to a BS sector sweep operation based on a combination of signal-to-noise measurement and angle-of-departure information corresponding to UEs in the service area obtained during the sector sweep operation.

16. The apparatus of claim IS, wherein membership in the group is determined based on a sector-specific preliminary CQA, wherein in response to the sector-sweep operation the UEs within the service area are grouped according to sector.

17. The apparatus of claim 16, wherein the processing circuitry receives instructions to encode the CQA periodically.

18. The apparatus of claim 17, wherein the processing circuitry is to receive and carry out multi-user multiple input/multiple output (MU-MIMO) instructions to transmit aperiodic CQA signaling.

19. At least one machine-readable medium containing instructions that, when executed on a processor of a radio access network (RAN) base station configurable for hybrid beam-forming (BF) radio communications with a set of user equipment (UEs) within a service area, cause the processor to:

decode CQA signaling from the UEs of the first subset to determine digital BF parameters for use with the hybrid BF radio communications.

20. The at least one machine-readable medium of claim 19, wherein the analog BF parameters are analog BF weights.

21. The at least one machine-readable medium of claim 19, wherein the first subset is selected based on a combination of signal-to-noise measurement and angle- of-departure information for individual ones of the UEs of the service area obtained during the sector sweep operation.

22. The at least one machine-readable medium according to any one of claims 19-21, wherein the first subset is selected based on a sector-specific preliminary CQA, wherein in response to the sector-sweep operation the UEs within the service area are grouped according to sector, and wherein the processing circuitry is to further encode signaling for transmission to UEs of each sector-group to configure those UEs to UEs to transmit first subset-specific CQA signaling concurrently.

23. The at least one machine-readable medium of claim 22, wherein the instructions are to cause the processor to further select a second subset of UEs from among the set of UEs, the second subset of UEs being selected based on a second set of BF sector membership attributes determined in the sector-sweep operation, the second subset of UEs to be subject to concurrent channel quality assessment (CQA) at a different symbol time than the CQA for the first subset; and

24. The at least one machine-readable medium of claim 22, wherein the first subset is selected further based on signal measurement of analog and digital BF- configured channels in response to the preliminary CQA.

25. The at least one machine-readable medium of claim 22, wherein the preliminary CQA is performed periodically.