WO2023126668A1

WO2023126668A1 - Amplitude-tapered codebook for time-domain beamforming

Info

Publication number: WO2023126668A1
Application number: PCT/IB2021/062497
Authority: WO
Inventors: Bo Göransson; Shashi Kant; Rohit Chandra
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2023-07-06

Abstract

Embodiments include methods for beamforming using an antenna array, by a node of a wireless network. Such methods include, for each pair of beamforming vectors (bk, bl) of a codebook comprising a plurality of beamforming vectors corresponding to a plurality of orientations (1...N), determining at least one corresponding pair of real-valued tapering vectors (tk, tl) such that when tapered beamforming vectors (tk∙bk, tl∙bl) are applied to the antenna array for concurrent transmission of beams of orientations (1≤k≤ N, 1≤l≤N, k≠l), radiated power of the antenna array is maximized subject to the beams of orientations (k, l) having sidelobes lower than associated thresholds in respective orientations (l, k). Such methods also include transmitting data concurrently in orientations (i, j), i≠j, based on weighting the portions of the antenna array by the tapered beamforming vectors (ti∙bi, tj∙bj) corresponding to orientations (i, j). Embodiments also include nodes configured to perform such methods.

Description

AMPLITUDE-TAPERED CODEBOOK FOR TIME-DOMAIN BEAMFORMING

TECHNICAL FIELD

The present disclosure relates generally to wireless communication networks, and more specifically to techniques for improving transmit beamforming in a wireless network.

BACKGROUND

Long-Term Evolution (LTE) is an umbrella term for so-called fourth-generation (4G) radio access technologies developed within the Third-Generation Partnership Project (3GPP) and initially standardized in Release 8 (Rel-8) and Release 9 (Rel-9), also known as Evolved UTRAN (E-UTRAN). LTE is targeted at various licensed frequency bands and is accompanied by improvements to non-radio aspects commonly referred to as System Architecture Evolution (SAE), which includes Evolved Packet Core (EPC) network. LTE continues to evolve through subsequent releases.

Currently the fifth generation (“5G”) of cellular systems, also referred to as New Radio (NR), is being standardized within the Third-Generation Partnership Project (3GPP). NR is developed for maximum flexibility to support multiple and substantially different use cases. These include enhanced mobile broadband (eMBB), machine type communications (MTC), ultra-reliable low latency communications (URLLC), side-link device-to-device (D2D), and several other use cases. NR was initially specified in 3GPP Release 15 (Rel-15) and continues to evolve through subsequent releases, such as Rel-16 and Rel-17.

5G/NR technology shares many similarities with LTE. For example, NR uses CP-OFDM (Cyclic Prefix Orthogonal Frequency Division Multiplexing) in the downlink (DL) from network to user equipment (UE), and both CP-OFDM and DFT-spread OFDM (DFT-S-OFDM) in the uplink (UL) from UE to network. As another example, NR DL and UL time-domain physical resources are organized into equal-sized 1-ms subframes. A subframe is further divided into multiple slots of equal duration, with each slot including multiple OFDM-based symbols. However, time-frequency resources can be configured much more flexibly for an NR cell than for an LTE cell. For example, rather than a fixed 15-kHz OFDM sub-carrier spacing (SCS) as in LTE, NR SCS can range from 15 to 240 kHz, with even greater SCS considered for future NR releases.

In addition to providing coverage via cells as in LTE, NR networks also provide coverage via “beams.” In general, a downlink (DL, i.e., network to UE) “beam” is a coverage area of a network-transmitted reference signal (RS) that may be measured or monitored by a UE. In NR, for example, RS can include any of the following: synchronization signal/Physical Broadcast Channel (PBCH) block (SSB), channel state information RS (CSI-RS), tracking reference signals (or any other sync signal), positioning RS (PRS), demodulation RS (DMRS), phase-tracking reference signals (PTRS), etc. In general, SSB is available to all UEs regardless of the state of their connection with the network, while other RS (e.g., CSI-RS, DM-RS, PTRS) are associated with specific UEs that have a network connection.

5G/NR networks are expected to operate at higher frequencies such as 25-60 GHz, which are typically referred to as “millimeter wave” or “mmW” for short. Such systems are also expected to utilize a variety of multi- antenna technology (e.g., antenna arrays) at the transmitter, the receiver, or both. In general, multi-antenna technology can include a plurality of antennas in combination with advanced signal processing techniques (e.g., beamforming). Multi-antenna technology can be used to improve various aspects of a communication system, including system capacity e.g., more users per unit bandwidth per unit area), coverage (e.g., larger area for given bandwidth and number of users), and increased per-user data rate (e.g., in a given bandwidth and area).

Availability of multiple antennas at the transmitter and/or the receiver can be utilized in different ways to achieve different goals. For example, multiple antennas at the transmitter and/or the receiver can be used to provide additional diversity against radio channel fading. To achieve such diversity, the channels experienced by the different antennas should have low mutual correlation, e.g., a sufficiently large antenna spacing (“spatial diversity”) and/or different polarization directions (“polarization diversity”).

As another example, multiple antennas at the transmitter and/or the receiver can be used to shape or “form” the overall antenna beam (e.g., transmit and/or receive beam, respectively) in a certain way, with the general goal being to improve the received signal-to-interference-plus- noise ratio (SINR) and, ultimately, system capacity and/or coverage. This can be done, for example, by maximizing the overall antenna gain in the direction of the target receiver or transmitter or by suppressing specific dominant interfering signals. More specifically, the transmitter and/or receiver can determine an appropriate weight for each antenna element in an antenna array so as to produce one or more beams, with each beam covering a particular range of azimuth and elevation relative to the antenna array.

In relatively good channel conditions, the capacity of the channel becomes saturated such that further improving the SINR provides limited capacity improvements. In such cases, using multiple antennas at both the transmitter and the receiver can be used to create multiple parallel communication "channels" over the radio interface. This can facilitate a highly efficient utilization of both the available transmit power and the available bandwidth resulting in, e.g., very high data rates within a limited bandwidth without a disproportionate degradation in coverage. For example, under certain conditions, the channel capacity can increase linearly with the number of antennas and avoid saturation in the data capacity and/or rates. These techniques are commonly referred to as “spatial multiplexing” or multiple-input, multiple-output (MIMO) antenna processing.

Accordingly, spatial multiplexing is a key feature to increase the spectral efficiency of wireless systems, including 5G/NR. Transmitting multiple layers on the same time-frequency resource can increase the data-rate for a single user (referred to as “SU-MIMO”). Alternatively, transmitting multiple layers on the same time-frequency resource to multiple users (referred to as “MU-MIMO”) can increase the system capacity in number of users.

Even so, transmitting multiple layers on the same resource requires sufficient spatial isolation to keep inter-layer interference at an acceptable level. This can be done by transmitting on different orthogonal polarizations, e.g., vertical and horizontal. Since there are only two orthogonal polarizations, however, this limits spatial multiplexing order to two. This is common in current wireless networks, particularly for SU-MIMO. The main constraint is in the UE, where it is difficult to fit an antenna array of many elements having sufficient spatial separation.

There are three main beamforming techniques: analog, digital, and hybrid (a combination of analog and digital). Analog beamforming can compensate for high mmW pathloss, while digital precoding can provide additional performance gains necessary to achieve a reasonable coverage. The implementation complexity of analog beamforming is significantly less than digital since it can utilize simple phase shifters, but it is limited in terms of multi-direction flexibility (i.e., a single beam can be formed at a time and the beams are then switched in time domain), transmission bandwidth (i.e., not possible to transmit over a sub-band), inaccuracies in the analog domain, etc.

Digital beamforming, which is often used today in LTE networks, provides the best performance in terms of data rate and multiplexing capabilities. For example, multiple beams over multiple sub-bands can be formed simultaneously. Even so, digital beamforming presents challenges in terms of power consumption, integration, and cost. Furthermore, while cost generally scales linearly with the number of transmit/receive units, the gains of digital beamforming increase more slowly.

Figure 1 A shows an exemplary hybrid transmit beamforming arrangement, which includes baseband processing circuitry (120) coupled to an analog beamformer (BF, 140) via intermediate conversion circuitry (130). The baseband processing circuitry includes a MIMO-related functionality such as layer mapping and precoding. The conversion circuitry can include one or more conversion chains, with multiple conversion chains shown in the figure. Each conversion chain can include an Inverse Fast Fourier Transform (IFFT), a parallel-to-serial (P/S) converter, and a digital- to- analog converter (DAC). The analog beamformer includes a transmitter (142, also referred to as transmit circuitry) and an antenna array (144). Additionally, the arrangement shown in Figure 1A includes processing/control circuitry (110) that manages and/or controls the baseband processing circuitry, the conversion circuitry, and the transmitter.

Figure IB shows an exemplary arrangement of analog beamformer 140. In this arrangement, antenna array 144 includes two panels (or sub-panels), with each panel including eight (8) two-element sub-arrays. Each antenna element provides vertical and horizontal polarization, as indicated by crosses in the respective circles. Transmitter 142 includes an independent beamforming circuit for each panel, with each beamforming circuit including an upconverter (e.g., mixer) from intermediate frequency (IF) to radio frequency (RF), as well as independent phase shifters and power amplifiers (PAs, also referred to as variable gain amplifiers (VGAs)) for each two-element sub-array.

Figure 1C shows another exemplary arrangement of analog beamformer 140. In this arrangement, antenna array 144 includes one antenna panel with 16 two-element sub-arrays. Each antenna element provides vertical and horizontal polarization, as indicated by crosses in the respective circles. Transmitter 142 includes one beamforming circuit arranged in a similar manner as shown in Figure IB. In this exemplary arrangement, only a single conversion chain is needed in conversion circuitry 130 shown in Figure 1A.

Note that the exemplary transmitters 142 shown in Figures 1B-C feed a single polarization on the antenna array 144. Duplicate transmitters 142 can be used to feed the respective horizontal and vertical polarizations on the antenna array 144.

Figure ID shows an alternative four-element sub-array that can be substituted for the two- element sub-arrays in either of Figures IB and 1C. This four-element sub-array has two feed ports, one for vertical polarization of all four elements and the other for horizontal polarization of all four elements. Each feed port can be connected to one of the PAs shown in Figures 1B-1C.

Although the antenna arrays shown in Figures 1B-1C are two-dimensional grids of elements, this is only exemplary. Other exemplary antenna arrays can have linear and/or onedimensional arrangements of elements.

A beamformer steers the analog beam of each antenna panel toward a single orientation or direction for each polarization on each OFDM symbol. For example, the processing/control circuitry can configure the phase shifters and the PAs associated with each subarray to generate a beam having a desired orientation. The number of subarrays in a panel determines the array gain for the panel. The arrangement shown in Figure IB supports one beam per panel per polarization (four total for two panels and two polarizations), while the arrangement shown in Figure 1C supports only one beam per polarization (two total).

For systems deployed at mmW frequencies, it is common to perform beamforming on the time-domain (TD) signal after OFDM transformation. The beamforming operation can either be performed by analog circuitry or by a digital implementation before digital-to-analog conversion (e.g., in the digital precoding section of Figure 1A). Since it is difficult to implement several analog beamforming networks (e.g., phase shifters and PAs) behind one antenna element, multi-layer transmission is often implemented with several panels, with each panel transmitting a single layer per polarization.

For TD beamforming, inter-layer isolation is typically provided by spatial nulling of inter- beam/inter-layer interference. In other words, when transmitting one layer, the applied BF weights should create maximal gain towards this layer while the gain should be very low in the directions where the other layers should go.

Beamforming codebooks can be used to reduce signaling requirements. For example, a list of beamforming vectors can be stored in a table in both the network node and the UE, or identified by a particular RS (e.g., a CSI-RS index). By using a fixed and finite codebook of BF vectors, only indices of selected BF vectors need to be sent from a network node’s processing unit (also referred to as digital unit or DU) via the interface to a beamforming radio unit.

As a more specific example, a codebook (B) of N beamforming vectors (bl ... bN) corresponding to respective orientations (1 ... N) can be used for coverage of a cell. Such a codebook can also be referred to as a “grid of beams” (GoB). The choice of beamforming vectors (bl ... bN) dictates beam parameters such as peak power and width of beam main lobe as well as level of beam sidelobes. Conventional choices for beamforming vectors (bl ... bN) produce beam parameters that are unsuitable in some manner, such as too low peak power or too high sidelobes. New techniques are needed to determine beamforming vectors that are more suitable for applications in wireless networks, such as in mmW applications.

SUMMARY

Embodiments of the present disclosure provide specific improvements to beamforming in a wireless network (e.g., radio access network, RAN), such as by providing, enabling, and/or facilitating solutions to overcome exemplary problems summarized above and described in more detail below.

Embodiments include methods e.g., procedures) for beamforming using an antenna array. These exemplary methods can be performed by a node of a wireless network, such as a network node (e.g., base station, eNB, gNB, ng-eNB, etc. or component thereof) or a user equipment (UE, e.g., wireless device, etc. or component thereof).

These exemplary methods can include, for each pair of beamforming vectors (bk, bl) of a codebook (B) comprising a plurality of beamforming vectors (bl ... bN) corresponding to a respective plurality of orientations (1 ... N), determining at least one corresponding pair of real- valued tapering vectors (tk, tl) such that when tapered beamforming vectors (tk-bk, tl-bl) are applied to portions of the antenna array for transmitting concurrent beams of orientations (1 < k < N, 1 < I < N, k Z), radiated power of the antenna array is maximized subject to the beams of orientations (k, Z) having sidelobes that are lower than associated thresholds (5k, 51) in respective orientations (Z, k).

These exemplary methods can also include transmitting data concurrently in orientations (1 < i < N, 1 < j < N, i j) based on weighting the portions of the antenna array by the tapered beamforming vectors (ti-bi, tj-bj) corresponding to the orientations (z, j).

In some embodiments, each beamforming vector (bl ... bN) and each tapering vector (tk, tl) comprises M values corresponding to respective M portions of the antenna array. In such embodiments, the data is transmitted via respective power amplifiers (PA-1 . . . PA-M) coupled to the M portions of the antenna array. In some embodiments, N can be an integer multiple of M.

In some embodiments, each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of each tapering vector (tk, tl) are less than or equal to respective maximum output powers (pl . . . pM) of the power amplifiers.

In other embodiments, each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of each tapered beamforming vectors (tk-bk, tl-bl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers.

In other embodiments, each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of (a-tk + p-tl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers, where a > 0, P > 0, and a + P = 1.

In some embodiments, each of the M values of each tapering vector is from the set (vl ... vR), where R = 2^r. For example, r can be the number of bits used to represent each of the M values. In some embodiments, r can be less than or equal to six (6).

In such embodiments, the determining operations can include, for each pair of beamforming vectors (bk, bl): evaluating radiated power and sidelobes of respective pairs of candidate tapering vectors having different combinations of M values selected from the set (vl ... vR); and selecting, as (tk, tl), the pair of candidate tapering vectors that maximizes radiated power subject to the sidelobes being lower than the respective thresholds (5k, 51) in orientations (Z, k).

In some embodiments, the M portions of the antenna array can be respective antenna elements. In other embodiments, the M portions of the antenna array can be respective antenna sub-arrays, with each sub-array including a plurality of antenna elements. In either case, the M values of the tapered beamforming vectors are used to weight the respective M portions.

In some embodiments, these exemplary methods can also include forming a codebook (T) comprising a plurality of entries indicating respective pairs of tapering vectors (tk, tl) determined for orientations (k, T), 1 < k < N, 1 < I < N, k I. For example, each entry can include a pair of tapering vectors.

In some of these embodiments, transmitting data concurrently can include selecting an entry in codebook (T) and entries in codebook (B) that correspond to the orientations (i, ), and forming the tapered beamforming vectors (ti-bi, tj-bj) based on the selected entry from codebook (T) and the selected entries from codebook (B). These vectors can then be used to weight the M portions of the antenna array.

In some embodiments, the thresholds (5k, 51) associated with the beams of orientations (k, Z) are -25 dB relative to the power of the beams of orientations (Z, k). Other thresholds relative to beam power can also be used according to requirements of particular applications.

In other embodiments, the thresholds (5k, 51) used for determining the tapering vectors can be dependent on and/or related to modulation and coding schemes (MCS) used to transmit data in the respective beams. In some of these embodiments, the determining operations can include the following: determining a first pair of real-value tapering vectors (tk-1, tl-1) based on first thresholds (5k-l, 51-1) corresponding to first modulation and coding schemes (MCSk-1, MCS1-1) for the beams of orientations (k, Z); and determining a second pair of real-value tapering vectors (tk-2, tl-2) based on second thresholds (5k-2, 51-2) corresponding to second modulation and coding schemes (MCSk-2, MCS1-2) for the beams of orientations (k, Z). In such embodiments, the transmitting operations can include selecting, as (ti, tj), either the first pair of tapering vectors (ti- 1, tj- 1) or the second pair of tapering vectors (ti-2, tj-2) based on modulation and coding schemes (MCSi, MCSj) used for the data carried by the beams of orientations (/, /).

Other embodiments include nodes (e.g., UEs, wireless devices, base stations, eNBs, gNBs, ng-eNBs, etc., or components thereof) configured to perform operations corresponding to any of the exemplary methods described herein. Other embodiments include non-transitory, computer- readable media storing program instructions that, when executed by processing circuitry, configure such nodes to perform operations corresponding to any of the exemplary methods described herein.

These and other embodiments can be more efficient than conventional amplitude tapering techniques, which generate overly-restrictive beams having low sidelobes in many different orientations rather than only in orientations of co-scheduled layers. Additionally, embodiments waste less transmit power due to sidelobe suppression, such that more transmit power is available for the main lobes of concurrent beams. Embodiments also provide flexible tradeoffs between sidelobe suppression and main lobe power based on a configurable interference threshold. Furthermore, beamforming vector codebooks can be kept relatively small since they are only required to include beam weights for individual orientations/users (e.g., SU-MIMO). These and other objects, features, and advantages of embodiments of the present disclosure will become apparent upon reading the following Detailed Description in view of the Drawings briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A-1D show various arrangements for transmit beamforming.

Figure 2 shows beams of a 32-vector DFT beamforming codebook covering an orientation range of +/- 90 degrees.

Figure 3 shows an exemplary arrangement of applying a Bartlett window to each vector of the DFT codebook illustrated in Figure 2.

Figure 4 shows another exemplary arrangement of applying a Hamming window to each vector of the DFT codebook illustrated in Figure 2.

Figure 5 shows the beams generated by a 32-vector DFT beamforming codebook (B), without amplitude tapering, as applied to an eight-element uniform linear antenna array (ULA).

Figure 6 shows the beams generated by the exemplary codebook (B) based on amplitude tapering with a symmetric Hanning window.

Figure 7 shows a comparison of two beams based on amplitude tapering according to embodiments of the present disclosure vs. two beams without amplitude tapering, such as shown in Figure 5.

Figure 8 shows a comparison of two beams based on amplitude tapering according to embodiments of the present disclosure vs. two beams with amplitude tapering using a symmetric Hanning windows, such as shown in Figure 6.

Figure 9 shows a flow diagram of an exemplary method for a node (e.g., UE, wireless device, base station, eNB, gNB, ng-eNB, etc.) of a wireless network, according to various embodiments of the present disclosure.

Figure 10 illustrates a high-level view of an exemplary 5G/NR network architecture.

Figure 11 shows a block diagram of an exemplary UE (e.g., wireless device), according to various embodiments of the present disclosure.

Figure 12 shows a block diagram of an exemplary network node e.g., base station, eNB, gNB, ng-eNB, etc.), according to various embodiments of the present disclosure.

Figure 13 shows a block diagram of an exemplary network configured to provide over- the-top (OTT) data services between a host computer and a UE, according to various embodiments of the present disclosure. DETAILED DESCRIPTION

Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used. All references to a/an/the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where a step must necessarily follow or precede another step due to some dependency. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description.

Furthermore, the following terms are used throughout the description given below:

• Radio Node: As used herein, a “radio node” can be either a radio access node or a wireless device.”

• Node: As used herein, a “node” can be a network node or a wireless device.

• Radio Access Node: As used herein, a “radio access node” (or equivalently “radio network node,” “radio access network node,” or “RAN node”) can be any node in a radio access network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station e.g., a New Radio (NR) base station (gNB) in a 3GPP Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP LTE network), base station distributed components (e.g., CU and DU), a high-power or macro base station, a low-power base station (e.g., micro, pico, femto, or home base station, or the like), an integrated access backhaul (IAB) node, a transmission point, a remote radio unit (RRU or RRH), and a relay node.

• Core Network Node: As used herein, a “core network node” is any type of node in a core network. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a serving gateway (SGW), a Packet Data Network Gateway (P-GW), an access and mobility management function (AMF), a session management function (AMF), a user plane function (UPF), a Service Capability Exposure Function (SCEF), or the like.

• Wireless Device: As used herein, a “wireless device” (or “WD” for short) is any type of device that has access to (i.e., is served by) a cellular communications network by communicate wirelessly with network nodes and/or other wireless devices. Communicating wirelessly can involve transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information through air. Some examples of a wireless device include, but are not limited to, smart phones, mobile phones, cell phones, voice over IP (VoIP) phones, wireless local loop phones, desktop computers, personal digital assistants (PDAs), wireless cameras, gaming consoles or devices, music storage devices, playback appliances, wearable devices, wireless endpoints, mobile stations, tablets, laptops, laptop- embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customer-premise equipment (CPE), mobile-type communication (MTC) devices, Internet-of-Things (loT) devices, vehicle-mounted wireless terminal devices, etc. Unless otherwise noted, the term “wireless device” is used interchangeably herein with the term “user equipment” (or “UE” for short).

• Network Node: As used herein, a “network node” is any node that is either part of the radio access network (e.g., a radio access node or equivalent name discussed above) or of the core network (e.g., a core network node discussed above) of a cellular communications network. Functionally, a network node is equipment capable, configured, arranged, and/or operable to communicate directly or indirectly with a wireless device and/or with other network nodes or equipment in the cellular communications network, to enable and/or provide wireless access to the wireless device, and/or to perform other functions (e.g., administration) in the cellular communications network.

Note that the description herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system. Furthermore, although the term “cell” is used herein, it should be understood that (particularly with respect to 5G NR) beams may be used instead of cells and, as such, concepts described herein apply equally to both cells and beams.

As briefly mentioned above, conventional choices for beamforming vectors (bl ... bN) produce beam parameters that are unsuitable in some manner, such as too low peak power or too high sidelobes. This is discussed in more detail below. The maximum gain for a beamformer can be achieved with a codebook of N Discrete Fourier Transform (DFT) vectors. In other words, the vectors (bl ... bN) correspond to N different DFT orthogonal basis functions. The DFT vectors provide a set of beams equally spaced in orientation over a range of interest. This arrangement provides the narrowest beam and also full utilization of PAs, but at the expense of high sidelobes. This is illustrated in Figure 2 for a 32-eIement DFT codebook (i.e., N=32) covering a range of +/- 90 degrees, where the maximum sidelobe for each beam is only 13dB below the peak for that beam. These high sidelobes produce interference to other beams, which can be problematic when transmitting multiple layers/beams.

One way to reduce sidelobes and improve layer isolation is amplitude tapering, i.e., by reducing amplitude of certain elements of each beamforming vector (bl ... bN) in a systematic way. This is also referred to as “windowing” the beamforming vectors. Figure 3 shows an exemplary arrangement of applying a Bartlett window to each vector of the 32-eIement DFT codebook illustrated in Figure 2. Applying the Bartlett window reduces the maximum sidelobe to ~19dB below the respective peaks for the beams, but at the expense of a peak power loss of 3-4 dB relative to the non- windowed case shown in Figure 2.

Figure 4 shows another exemplary arrangement of applying a Hamming window to each vector of the 32-eIement DFT codebook illustrated in Figure 2. Applying the Hamming window reduces the maximum sidelobe to ~26dB below the respective peaks for the beams, but again at the expense of a peak power loss of 3-4 dB relative to the non-windowed case shown in Figure 2. Both windows produce beams with wider main lobes than the non-windowed case, with Hamming windowed beams having wider main lobes than Bartlett windowed beams.

Note that the above examples involve amplitude-only tapering, which can be implemented simply by adjusting the amplitude (or power) per PA. Introducing phase adjustments to the tapering (e.g., complex window values) increases complexity, particularly for analog beamforming but also for digital precoding. Accordingly, it can be beneficial to use amplitude- only tapering.

Even so, the loss of peak power due to the tapering can be problematic. For example, a loss of 3-4 dB as in Figures 3-4 can reduce coverage and/or DL capacity in the cell. When the beamforming vectors (bl ... bN) are used for transmissions by the UE, the loss of peak power can be very problematic for UL coverage because UEs are already more limited in UL performance due to output power restrictions. The broadening of the beams due to conventional amplitude tapering is also problematic since it increases spatial separation requirements of concurrently transmitted beams.

Applicants have recognized that, in general, the sidelobe suppression provided by conventional amplitude tapering is relatively uniform across the range of orientations outside of the beam’ s main lobe. Applicants have also recognized that such uniform sidelobe suppression is not necessary in practical implementations. In other words, if two beams are being transmitted concurrently in respective orientations (k, 1), then the sidelobe suppression is of particular importance only in orientations (k, 1). In other words, the sidelobe for the beam of orientation k must be sufficiently suppressed in orientation 1, and the sidelobe for the beam of orientation 1 must be sufficiently suppressed in orientation k. This requirement can be extended to concurrent transmission of beams in more than two orientations.

In addition to sidelobe suppression, such beams should also have the greatest amount of peak power in the main lobe. In other words, the peak power in orientations (k, 1) should be as close to the maximum as technically feasible. Note that the terms “orientation” and “layer” may be used synonymously for MU-MIMO, since it is assumed that each layer is transmitted in a different orientation to a different user.

Embodiments of the present disclosure address these and other problems, issues, and/or difficulties by providing techniques to determine real-valued, amplitude-only tapering vectors that minimize the leakage between two (or more) spatial layers transmitted concurrently from the same array while maximizing the transmitted power. For a particular orientation, there will be one tapering vector per polarization in a single panel implementation and one tapering vector per panel and polarization for multi-panel implementations (e.g., two or more).

Embodiments are applicable to transmission from a network node or from a UE. In the network node case, each UE can report a preferred beamforming vector index (1 ... N) that identifies one of the beamforming vectors (bl ... bN) in the codebook B. In some embodiments, each UE can also report an associated quality measure (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), SINR, etc.) for a DL beam (e.g., CSI-RS, SSB) corresponding to the reported index. Assume that two UEs identify indices (i, j) corresponding to beamforming vectors (bi, bj). The network can use amplitude tapering vectors (ti, tj) that maximize the transmitted power in orientations (i, j) while keeping interfering power in orientations (j, i) (i.e., for the concurrently scheduled UE) below an acceptable level or threshold. This can be expressed as the following optimization criteria or problem:

Maximize Ptx(ti, tj) subject to: (1) lwi^H wjl < 5 ;

0 < ti(m) < pm, 0 < tj(m) < pm, 1 < m < M ; and

1 < i < N, 1 <j < N, i j , where Ptx(ti, tj) is radiated power of the antenna array based on selecting (ti, tj); wi = (ti • bi) and wj = (tj • bj) (referred to as “tapered beamforming vectors”) are element-wise (or Hadamard) products of tapering and beamforming vectors of the same length, M; “wi^H wj” is the inner product of the two vectors, with superscript “H” denoting Hermitian (complex conjugate transpose); “Ixl” denotes absolute value of the argument, x; 5 is an interference threshold; and pm for (1 < m <M) are the maximum power output capabilities of the respective PAs (e.g., dBm, mW, W, etc.).

Embodiments of the present disclosure can provide various benefits, advantages, and/or solutions to various problems. For example, multi-layer transmission from a TD-BF system can be more efficient compared to conventional amplitude tapering techniques, which generate overly-restrictive beams having low sidelobes in many different orientations rather than only in orientations of co-scheduled layers. Additionally, numerical simulations have shown that less power is wasted on suppressing sidelobes in many different orientations, and hence more power is available for the main lobes of the concurrent beams.

Furthermore, embodiments provide flexibility in tradeoffs between sidelobe suppression and main lobe power by choosing an appropriate value for interference threshold 5. A further advantage is that the beamforming vector codebook B can be kept relatively small since it is only required to include beam weights for individual orientations/users (e.g., SU-MIMO). Weights suitable for MU-MIMO (or higher order SU-MIMO) will be derived by applying the amplitude tapering vectors to the beamforming vectors of codebook B.

Additionally, embodiments provide the flexibility to compute the tapering vectors offline and/or beforehand, independent of the symbol-rate transmissions during operations. As such, a codebook T of pairs of tapering vectors (tk, tl) corresponding to orientations (k, I) can be formed initially for all orientations 1 < k < N, 1 < Z < N, k l. Determining such a codebook depends primarily on the selection of the sidelobe interference threshold 5. Accordingly, it is possible to determine different codebooks T for different values of 8 depending on the necessary sidelobe interference suppression. Several codebooks T can be derived and indexed by, e.g., the degree of sidelobe interference suppression provided. However, it should be noted that increasing the sidelobe interference suppression will, in most cases, lead to a larger main lobe power loss due to more excessive amplitude tapering.

For a multi-panel arrangement in which one layer is transmitted per panel, the total transmitted power (per panel) can be written as Ptx = wk^H wk, where wk is the tapered beamforming vector for orientation k. But since wk = tk • bk, Ptx can also be written as:

Ptx = (tk • bk)^H (tk • bk), (2)

Or in the following vector-matrix format:

P_tx = fc"7i b_k, (3) where Tk is a diagonal (MxM) matrix with elements of tapering vector tk on its diagonal and zeros elsewhere, and bk^H indicates Hermitian (complex conjugate transpose) of beamforming vector bk.

The optimization problem given by (1) with orientations (k, 1) is not a convex function of (tk, tl), such that there is generally no easy mathematical solution. In some embodiments, however, the solution can be performed off-line with the results stored in a codebook T. In some embodiments, an exhaustive search can be performed over all possible combinations of tapering vectors (tk, tl) corresponding to orientations (k, 1), and for all orientations l < k <A, 7 < 1 <A, k A 1- In other words, for an N-element codebook B, we need to find the optimal tapering vectors (tk, tl) when two layers are co-scheduled in orientations (k, 1). This must be done for all orientations 1 < k </V, I < 1 <N, k A 1-

In some embodiments, the complexity of an exhaustive search can be reduced by limiting the resolution of the elements of the tapering vectors (tk, tl). In other words, the number of values between 0 and pm for each (tk(m), tl(m)), 1 < m < M, can be limited. In some embodiments, each of the values (tk(m), tl(m)) is from the limited set (vl ... vR), where R = 2^r. In some embodiments, 6 < r < 8 such that 64-256 values must be evaluated for each tapering vector element. In some embodiments, r can be less than or equal to six, which can further reduce complexity of the search.

In such embodiments, the beamforming vectors (bl ... bN) may be already tapered in amplitude such that bk = ck • dk, where dk is a non-tapered vector (e.g., DFT vector) and ck is an amplitude tapering vector having elements 0 < ck(m) < 1 , 1 < m < M. Such tapering can be used, for example, to reduce beam sidelobes that may interfere with a neighboring coverage area. An example is shown in Figures 2-4, where beams toward the edge of the +/-90-degree coverage area have main lobes with lower peak power and different shapes than the beams in the middle of the coverage area. In such embodiments, the optimization problem of (1) can be reformulated as: Maximize Ptx(tk, tl) subject to: (4) lwk^H wll < 5 ;

0 < ck(m)tk(m) < pm, 0 < cl(m)tl(m) < pm, 1 < m < M ; and 1 < k < N, 1 < l < N, k ^ l .

The following example further illustrates various embodiments described above. In this example, the beamforming vector codebook B contains DFT vectors generated from a Q=4 times oversampled DFT. In other works, B = (bl ... b32) and each beamforming vector includes M = 8 values that are applied to respective M = 8 elements of a uniform linear antenna array (ULA). Figure 5 shows the beams generated by this exemplary codebook B without amplitude tapering. Note that due to the oversampling, the respective beamforming vectors are not orthogonal. Two users in orientations (k, 1) need to be scheduled concurrently for beams transmitted by respective antenna panels 1 and 2. The heavy solid line shows the preferred beam for orientation k and the heavy dashed line shows the preferred beam for orientation I. In this example, the interference caused by non-orthogonal beam vectors is (bk * bl) = 0.15 for (bk * bk) = (bl * bl) = 1.0, which is an inter-beam isolation of only 8 dB. This is insufficient for spatial multiplexing.

Figure 6 shows the beams generated by the exemplary codebook B after tapering with symmetric Hanning windows. As compared to the non-tapered beams, the Hanning windowed beams have significantly lower sidelobes but suffer from power loss in the main lobes. In particular, (bk * bl) = 0.004, which provides 24 dB isolation. However, (bk * bk) = (bl * bl) = 0.4, which is a loss of almost 4 dB in the main lobes.

Figure 7 shows a comparison of beams of orientations (k, Z) based on tapering vectors generated according to embodiments of the present disclosure vs. beams without amplitude tapering, such as shown in Figure 5. In this example, the optimization problem formulated in (1) is solved by an exhaustive search based on 8 < 0.003 (-25dB) and 0 < tk(m), tl(m) < 1 for 1 < m < M. The resulting main lobes suffer from power loss of less than 0.5 dB relative to the nontapered beams and the isolation between the beams is -26 dB.

Figure 8 shows a comparison of beams of orientations (k, Z) based on tapering vectors generated according to embodiments of the present disclosure vs. beams generated by tapering with symmetric Hanning windows, such as shown in Figure 6. Both methods produce a similar inter-beam isolation, but the Hanning windowed beams suffer from significantly more power loss in the main lobes.

The above description has focused on the multi-panel case, e.g., two panels for two spatial layers/users/orientations. If several beamforming networks are available between each antenna, it is possible to transmit several layers from the same panel. This can be implemented by analog or digital techniques. With a digital implementation, several beams can be generated by multiplying each data stream (layer) with its own beam vector before summing the signals. This summed signal is then up converted to RF.

Unlike the multi-panel case, available transmit power is shared between layers for the single panel case. Hence there is a constraint on the total power per PA. In this case, the optimization problem in (1) can be reformulated as:

Maximize Ptx(tk, tl) subject to: (5) lwk^H wll < 5 ;

0 < (a tk(m) + P tl(m)) < pm, tk(m) > 0, tl(m) > 0, 1 < m < M; 0 < a < l, 0 < P < l, a+ P = 1; and

1 < k < N, l < l < N, k ^ l . where a and p are user-defined real- valued parameters used to allocate power to the different layers transmitted in orientations (k, 1).

Embodiments are also applicable to the single -panel case in which beamforming vectors in codebook B are amplitude tapered. In such embodiments, the optimization problems in (4) and (5) can be combined to provide the constraint of 0 < (a ck(m) tk(m) + P cl(m) tl(m)) < pm.

Various features of the embodiments described above correspond to various operations illustrated in Figure 9, which shows an exemplary method (e.g., procedures) for beamforming using an antenna array. The method can be performed by a node of a wireless network, such as a network node (e.g., base station, eNB, gNB, ng-eNB, etc. or component thereof) or a user equipment (UE, e.g., wireless device, etc. or component thereof) such as described elsewhere herein. Although Figure 9 shows specific blocks in a particular order, the operations of the exemplary method can be performed in different orders than shown and can be combined and/or divided into blocks having different functionality than shown. Optional blocks or operations are indicated by dashed lines.

The exemplary method can include the operations of block 910, where the node can, for each pair of beamforming vectors (bk, bl) of a codebook (B) comprising a plurality of beamforming vectors (bl ... bN) corresponding to a respective plurality of orientations (1 ... N), determine at least one corresponding pair of real- valued tapering vectors (tk, tl) such that when tapered beamforming vectors (tk-bk, tl-bl) are applied to portions of the antenna array for transmitting concurrent beams of orientations (1 < k < N, 1 < I < N, k Z), radiated power of the antenna array is maximized subject to the beams of orientations (k, Z) having sidelobes that are lower than associated thresholds (5k, 51) in respective orientations (Z, k). For example, the operations of block 910 can be used for solution of any of the optimization problems described above.

Note that constraining beams of orientations (k, Z) to have sidelobes lower than associated thresholds (5k, 51) in respective orientations (Z, k) is less restrictive than constraining beams of orientations (k, Z) to have sidelobes lower than associated thresholds (5k, 51) in all orientations. By removing and/or weakening restrictions on sidelobes in orientations other than (k, Z), embodiments waste less transmit power on sidelobe suppression and make more transmit power available for main lobes of concurrent beams. Even so, beams of orientations (k, Z) may have sidelobes lower than associated thresholds (5k, 51) in orientations other than (Z, k), but this is not a requirement and/or constraint.

The exemplary method can also include the operations of block 930, where the node can transmit data concurrently in orientations (1 < i < N, 1 <j < N, i f) based on weighting the portions of the antenna array by the tapered beamforming vectors (ti-bi, tj-bj) corresponding to the orientations (z,j).

In some embodiments, each beamforming vector (bl ... bN) and each tapering vector (tk, tl) comprises M values corresponding to respective M portions of the antenna array. In such embodiments, the data is transmitted (e.g., in block 930) via respective power amplifiers (PA-1 . . . PA-M) coupled to the M portions of the antenna array. In some embodiments, N can be an integer multiple of M, such as the example of N = 32 and M = 8 discussed above.

In some embodiments, each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of each tapering vector (tk, tl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers. An example of these embodiments is the optimization criteria of equation (1) above.

In other embodiments, each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of each tapered beamforming vector (tk-bk, tl-bl) are less than or equal to respective maximum output powers (pl . . . pM) of the power amplifiers. An example of these embodiments is the optimization criteria of equation (4) above, where the beamforming vectors (bk, bl) have been pre-tapered with amplitude vectors (ck, cl).

In other embodiments, each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of (a-tk + p-tl) are less than or equal to respective maximum output powers (pl . . . pM) of the power amplifiers, where a > 0, P > 0, and a + P = 1. An example of these embodiments is the optimization criteria in equation (5) above for a singlepanel case.

In such embodiments, the determining operations of block 910 can include the operations of sub-blocks 911-912, for each pair of beamforming vectors (bk, bl). In sub-block 911, the node can evaluate radiated power and sidelobes of respective pairs of candidate tapering vectors having different combinations of M values selected from the set (vl ... vR). In sub -block 912, the node can select, as (tk, tl), the pair of candidate tapering vectors that maximizes radiated power subject to the sidelobes being lower than the respective thresholds (5k, 51) in orientations (Z, k).

In some embodiments, the M portions of the antenna array can be respective antenna elements. In other embodiments, the M portions of the antenna array can be respective antenna sub-arrays, with each sub-array including a plurality of antenna elements. In either case, the M values of the tapered beamforming vectors are used to weight the respective M portions, e.g., in block 930.

In some embodiments, the exemplary method can also include the operations of block 920, where the node can form a codebook (T) comprising a plurality of entries indicating respective pairs of tapering vectors (tk, tl) determined for orientations

1 < k < N, 1 < I < N, k I. For example, each entry can include a pair of tapering vectors. In some of these embodiments, transmitting data concurrently in block 930 can include the operations of sub-blocks 931-933. In sub-blocks 931-932, the node can select an entry in codebook (T) that corresponds to the orientations (i, j) and select entries from codebook (B) that correspond to the orientations (i, j). For example, the entries from codebook (B) can include the beamforming vectors (bi, bj). In subblock 933, the node can form the tapered beamforming vectors (ti-bi, tj-bj) based on the selected entry from codebook (T) and the selected entries from codebook (B). These vectors can then be used to weight the M portions of the antenna array.

The operations of block 910 are described above as determining at least one corresponding pair of real-valued tapering vectors (tk, tl) for each pair of beamforming vectors (bk, bl) of a codebook (B). However, this should not be understood as requiring an entire codebook (T) of tapering vector pairs to be determined prior to transmitting data. For example, each pair of tapering vectors (ti, tj) could be determined as needed for concurrent transmission in orientations (i, j). Once determined, such tapering vectors can be stored in the codebook (T) for later use.

In other embodiments, the thresholds (5k, 51) used for determining the tapering vectors can be dependent on and/or related to modulation and coding schemes (MCS) used to transmit data in the respective beams. For example, a single threshold can be selected based on the less robust (e.g., higher modulation order and/or less coding redundancy) of the two MCS used in beams of orientations (Z, k).

In some of these embodiments, the determining operations of block 910 can include the operations of sub-blocks 913-914. In sub-block 913, the node can determine a first pair of real- value tapering vectors (tk-1, tl-1) based on first thresholds (5k- 1, 51-1) corresponding to first modulation and coding schemes (MCSk-1, MCS1-1) for the beams of orientations (k, Z). In subblock 914, the node can determine a second pair of real-value tapering vectors (tk-2, tl-2) based on second thresholds (5k-2, 51-2) corresponding to second modulation and coding schemes (MCSk-2, MCS1-2) for the beams of orientations (k, Z). In other words, the node can determine two pairs of tapering vectors for a single pair of orientations (k, Z), each pair associated with a different pair of MCS for the beams. These operations can be further extended to additional pairs of MCS used for the beams of orientations (k, I).

In such embodiments, the transmitting operations in block 930 can include the operations of block 931, where the node can select, as (ti, tj), either the first pair of tapering vectors (ti-1, tj- 1) or the second pair of tapering vectors (ti-2, tj-2) based on modulation and coding schemes (MCSi, MCSj) used for the data carried by the beams of orientations (i, j). If additional pairs of tapering vectors are determined for additional pairs of MCS for the beams of orientations (i, j), then the node can further select from these additional pairs based on used (MCSi, MCSj).

As mentioned above, the exemplary method shown in Figure 9 can be implemented by a node (e.g., UE, base station, etc.) of a wireless network (e.g., E-UTRAN, NG-RAN, etc.). For example, the node can include an antenna array comprising a plurality of elements and transmitting circuitry operably coupled to the antenna array. Examples of this hardware arrangement are shown in Figures 1A-1D. Additionally, the node can include processing circuitry operably coupled to the transmitting circuitry and the antenna array, whereby the node is configured to perform operations corresponding to any of those described above with reference to Figure 9. For example, the processing circuitry can perform the operations of blocks 910-920 and can perform the operations of block 930 in cooperation with the transmitting circuitry and the antenna array.

However, the node hardware arrangement described above is merely exemplary. More specifically, the node can have any hardware arrangement that can be configured and/or arranged to perform operations corresponding to any of those described above with reference to Figure 9.

Additionally, the exemplary method shown in Figure 9 can be realized as a non-transitory, computer-readable medium storing computer-executable instructions. When executed by processing circuitry of a node configured for beamforming using an antenna array, the instructions configure the node to perform operations corresponding to any of those described above with reference to Figure 9.

Additionally, the exemplary method shown in Figure 9 can be realized as a computer program product comprising computer-executable instructions. When executed by processing circuitry of a node configured for beamforming using an antenna array, the instructions configure the node to perform operations corresponding to any of those described above with reference to Figure 9.

Figure 10 shows a high-level view of an exemplary 5G network architecture in which various embodiments of the present disclosure can be used. The exemplary architecture shown in Figure 10 includes a Next Generation Radio Access Network (NG-RAN) 1099 and a 5G Core (5GC) 1098. As shown in the figure, NG-RAN 1099 can include gNBs 1010 (e.g., 1010a, b) and ng-eNBs 1020 (e.g. , 1020a, b) that are interconnected with each other via respective Xn interfaces. The gNBs and ng-eNBs are also connected via the NG interfaces to 5GC 1098, more specifically to the AMF (Access and Mobility Management Function) 1030 (e.g., AMFs 1030a,b) via respective NG-C interfaces and to the UPF (User Plane Function) 1040 (e.g., UPFs 1040a,b) via respective NG-U interfaces. Moreover, the AMFs 1030a, b can communicate with one or more policy control functions (PCFs, e.g., PCFs 1050a, b) and network exposure functions (NEFs, e.g., NEFs 1060a, b).

Each of the gNBs 1010 can support the NR radio interface including frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof. In contrast, each of ng-eNBs 1020 can support the LTE radio interface but, unlike conventional LTE eNodeBs (eNBs), connect to the 5GC via the NG interface. Each of the gNBs and ng-eNBs can serve a geographic coverage area including one more cells, including cells lOlla-b and 1021a-b shown as exemplary in Figure 10. The gNBs and ng-eNBs can also use various directional beams to provide coverage in the respective cells. For example, the gNBs and ng-eNBs can be embodiments of a node coupled to an antenna array and configured to perform operations corresponding to the method shown in Figure 9. Depending on the particular cell in which it is located, a UE 1005 can communicate with the gNB or ng-eNB serving that cell via the NR or LTE radio interface, respectively. For example, UE 1005 can be an embodiment of a node that includes an antenna array and is configured to perform operations corresponding to the method shown in Figure 9.

The gNBs shown in Figure 10 can include a central (or centralized) unit (CU or gNB-CU) and one or more distributed (or decentralized) units (DU or gNB-DU), which can be viewed as logical nodes. CUs host higher-layer protocols and perform various gNB functions such controlling the operation of DUs, which host lower-layer protocols and can include various subsets of the gNB functions. As such, each of the CUs and DUs can include various circuitry needed to perform their respective functions, including processing circuitry, communication interface circuitry (e.g., for communication via Xn, NG, radio, etc. interfaces), and power supply circuitry. Moreover, the terms “central unit” and “centralized unit” can be used interchangeably, as can the terms “distributed unit” and “decentralized unit.”

A CU connects to its associated DUs over respective Fl logical interfaces. A CU and associated DUs are only visible to other gNBs and the 5GC as a gNB, e.g., the Fl interface is not visible beyond a CU. A CU can host higher-layer protocols such as Fl application part protocol (Fl-AP), Stream Control Transmission Protocol (SCTP), GPRS Tunneling Protocol (GTP), Packet Data Convergence Protocol (PDCP), User Datagram Protocol (UDP), Internet Protocol (IP), and Radio Resource Control (RRC) protocol. In contrast, a DU can host lower-layer protocols such as Radio Link Control (RLC), Medium Access Control (MAC), and physical-layer (PHY) protocols.

Other variants of protocol distributions between CU and DU can exist, however, such as hosting the RRC, PDCP and part of the RLC protocol in the CU (e.g., Automatic Retransmission Request (ARQ) function), while hosting the remaining parts of the RLC protocol in the DU, together with MAC and PHY. In some embodiments, the CU can host RRC and PDCP, where PDCP is assumed to handle both UP traffic and CP traffic. Nevertheless, other exemplary embodiments may utilize other protocol splits that by hosting certain protocols in the CU and certain others in the DU.

Figure 11 shows a block diagram of an exemplary wireless device or user equipment (UE) 1100 (hereinafter referred to as “UE 1100”) according to various embodiments of the present disclosure, including those described above with reference to other figures. For example, UE 1100 can be configured by execution of instructions, stored on a computer-readable medium, to perform operations corresponding to one or more of the exemplary methods described herein.

UE 1100 can include a processor 1110 (also referred to as “processing circuitry”) that can be operably connected to a program memory 1120 and/or a data memory 1130 via a bus 1170 that can comprise parallel address and data buses, serial ports, or other methods and/or structures known to those of ordinary skill in the art. Program memory 1120 can store software code, programs, and/or instructions (collectively shown as computer program product 1121 in Figure 11) that, when executed by processor 1110, can configure and/or facilitate UE 1100 to perform various operations, including operations corresponding to various exemplary methods described herein. As part of or in addition to such operations, execution of such instructions can configure and/or facilitate UE 1100 to communicate using one or more wired or wireless communication protocols, including one or more wireless communication protocols standardized by 3GPP, 3GPP2, or IEEE, such as those commonly known as 5G/NR, LTE, LTE-A, UMTS, HSPA, GSM, GPRS, EDGE, IxRTT, CDMA2000, 802.11 WiFi, HDMI, USB, Firewire, etc., or any other current or future protocols that can be utilized in conjunction with radio transceiver 1140, user interface 1150, and/or control interface 1160.

As another example, processor 1110 can execute program code stored in program memory 1120 that corresponds to MAC, RLC, PDCP, SDAP, RRC, and NAS layer protocols standardized by 3GPP (e.g., for NR and/or LTE). As a further example, processor 1110 can execute program code stored in program memory 1120 that, together with radio transceiver 1140, implements corresponding PHY layer protocols, such as Orthogonal Frequency Division Multiplexing (OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), and Single-Carrier Frequency Division Multiple Access (SC-FDMA). As another example, processor 1110 can execute program code stored in program memory 1120 that, together with radio transceiver 1140, implements device-to-device (D2D) communications with other compatible devices and/or UEs.

Program memory 1120 can also include software code executed by processor 1110 to control the functions of UE 1100, including configuring and controlling various components such as radio transceiver 1140, user interface 1150, and/or control interface 1160. Program memory 1120 can also comprise one or more application programs and/or modules comprising computerexecutable instructions embodying any of the exemplary methods described herein. Such software code can be specified or written using any known or future developed programming language, such as e.g., Java, C++, C, Objective C, HTML, XHTML, machine code, and Assembler, as long as the desired functionality, e.g., as defined by the implemented method steps, is preserved. In addition, or as an alternative, program memory 1120 can comprise an external storage arrangement (not shown) remote from UE 1100, from which the instructions can be downloaded into program memory 1120 located within or removably coupled to UE 1100, so as to enable execution of such instructions.

Data memory 1130 can include memory area for processor 1110 to store variables used in protocols, configuration, control, and other functions of UE 1100, including operations corresponding to, or comprising, any of the exemplary methods described herein. Moreover, program memory 1120 and/or data memory 1130 can include non-volatile memory (e.g., flash memory), volatile memory e.g., static or dynamic RAM), or a combination thereof. Furthermore, data memory 1130 can comprise a memory slot by which removable memory cards in one or more formats (e.g., SD Card, Memory Stick, Compact Flash, etc.) can be inserted and removed.

Persons of ordinary skill will recognize that processor 1110 can include multiple individual processors (including, e.g., multi-core processors), each of which implements a portion of the functionality described above. In such cases, multiple individual processors can be commonly connected to program memory 1120 and data memory 1130 or individually connected to multiple individual program memories and or data memories. More generally, persons of ordinary skill in the art will recognize that various protocols and other functions of UE 1100 can be implemented in many different computer arrangements comprising different combinations of hardware and software including, but not limited to, application processors, signal processors, general-purpose processors, multi-core processors, ASICs, fixed and/or programmable digital circuitry, analog baseband circuitry, radio-frequency circuitry, software, firmware, and middleware.

For example, radio transceiver 1140 can include transmitters, receivers, signal processors, ASICs, antennas, beamforming units, and other circuitry that enable UE 1100 to communicate with other equipment supporting like wireless communication standards and/or protocols, such as a compatible network node. In some embodiments, radio transceiver 1140 includes circuitry that enables UE 1100 to communicate according to various protocols and/or methods standardized by 3GPP and/or other standards bodies. For example, such functionality can operate cooperatively with processor 1110 to implement a PHY layer based on OFDM, OFDMA, and/or SC-FDMA technologies.

In some embodiments, radio transceiver 1140 includes circuitry, firmware, etc. necessary for the UE 1100 to communicate with various NR, NR-U, ETE, LTE-A, LTE-LAA, UMTS, and/or GSM/EDGE networks, also according to 3GPP standards. In some embodiments, radio transceiver 1140 includes circuitry, firmware, etc. necessary for the UE 1100 to communicate using radio technologies that operate in unlicensed frequency bands, such as IEEE 802.11 WiFi that operates using frequencies in the regions of 2.4, 5.6, and/or 60 GHz. In some embodiments, radio transceiver 1140 can include circuitry supporting D2D communications between UE 1100 and other compatible devices.

The functionality particular to each of these embodiments can be coupled with and/or controlled by other circuitry in the UE 1100, such as the processor 1110 executing program code stored in program memory 1120 in conjunction with, and/or supported by, data memory 1130.

User interface 1150 can take various forms depending on the particular embodiment of UE 1100, or can be absent from UE 1100 entirely. In some embodiments, user interface 1150 can comprise a microphone, a loudspeaker, slidable buttons, depressible buttons, a display, a touchscreen display, a mechanical or virtual keypad, a mechanical or virtual keyboard, and/or any other user-interface features commonly found on mobile phones. In other embodiments, the UE 1100 can comprise a tablet computing device including a larger touchscreen display. In such embodiments, one or more of the mechanical features of the user interface 1150 can be replaced by comparable or functionally equivalent virtual user interface features (e.g., virtual keypad, virtual buttons, etc.) implemented using the touchscreen display, as familiar to persons of ordinary skill in the art. In other embodiments, the UE 1100 can be a digital computing device, such as a laptop computer, desktop computer, workstation, etc. that comprises a mechanical keyboard that can be integrated, detached, or detachable depending on the particular exemplary embodiment. Such a digital computing device can also comprise a touch screen display. Many exemplary embodiments of the UE 1100 having a touch screen display are capable of receiving user inputs, such as inputs related to exemplary methods described herein or otherwise known to persons of ordinary skill.

In some embodiments, UE 1100 can include an orientation sensor, which can be used in various ways by features and functions of UE 1100. For example, the UE 1100 can use outputs of the orientation sensor to determine when a user has changed the physical orientation of the UE 1100’s touch screen display. An indication signal from the orientation sensor can be available to any application program executing on the UE 1100, such that an application program can change the orientation of a screen display (e.g., from portrait to landscape) automatically when the indication signal indicates an approximate 90-degree change in physical orientation of the device. In this exemplary manner, the application program can maintain the screen display in a manner that is readable by the user, regardless of the physical orientation of the device. In addition, the output of the orientation sensor can be used in conjunction with various exemplary embodiments of the present disclosure.

A control interface 1160 of the UE 1100 can take various forms depending on the particular exemplary embodiment of UE 1100 and of the particular interface requirements of other devices that the UE 1100 is intended to communicate with and/or control. For example, the control interface 1160 can comprise an RS-232 interface, a USB interface, an HDMI interface, a Bluetooth interface, an IEEE (“Firewire”) interface, an I²C interface, a PCMCIA interface, or the like. In some exemplary embodiments of the present disclosure, control interface 1160 can comprise an IEEE 802.3 Ethernet interface such as described above. In some exemplary embodiments of the present disclosure, the control interface 1160 can comprise analog interface circuitry including, for example, one or more digital-to-analog converters (DACs) and/or analog-to-digital converters (ADCs).

Persons of ordinary skill in the art can recognize the above list of features, interfaces, and radio-frequency communication standards is merely exemplary, and not limiting to the scope of the present disclosure. In other words, the UE 1100 can comprise more functionality than is shown in Figure 11 including, for example, a video and/or still-image camera, microphone, media player and/or recorder, etc. Moreover, radio transceiver 1140 can include circuitry necessary to communicate using additional radio-frequency communication standards including Bluetooth, GPS, and/or others. Moreover, the processor 1110 can execute software code stored in the program memory 1120 to control such additional functionality. For example, directional velocity and/or position estimates output from a GPS receiver can be available to any application program executing on the UE 1100, including any program code corresponding to and/or embodying any exemplary embodiments (e.g., of methods) described herein.

Figure 12 shows a block diagram of an exemplary network node 1200 according to various embodiments of the present disclosure, including those described above with reference to other figures. For example, exemplary network node 1200 can be configured by execution of instructions, stored on a computer-readable medium, to perform operations corresponding to one or more of the exemplary methods described herein. In some exemplary embodiments, network node 1200 can comprise a base station, eNB, gNB, or one or more components thereof. For example, network node 1200 can be configured as a central unit (CU) and one or more distributed units (DUs) according to NR gNB architectures specified by 3GPP. More generally, the functionally of network node 1200 can be distributed across various physical devices and/or functional units, modules, etc.

Network node 1200 can include processor 1210 (also referred to as “processing circuitry”) that is operably connected to program memory 1220 and data memory 1230 via bus 1270, which can include parallel address and data buses, serial ports, or other methods and/or structures known to those of ordinary skill in the art.

Program memory 1220 can store software code, programs, and/or instructions (collectively shown as computer program product 1221 in Figure 12) that, when executed by processor 1210, can configure and/or facilitate network node 1200 to perform various operations, including operations corresponding to various exemplary methods described herein. As part of and/or in addition to such operations, program memory 1220 can also include software code executed by processor 1210 that can configure and/or facilitate network node 1200 to communicate with one or more other UEs or network nodes using other protocols or protocol layers, such as one or more of the PHY, MAC, RLC, PDCP, SDAP, RRC, and NAS layer protocols standardized by 3GPP for LTE, LTE-A, and/or NR, or any other higher-layer protocols utilized in conjunction with radio network interface 1240 and/or core network interface 1250. By way of example, core network interface 1250 can comprise the SI or NG interface and radio network interface 1240 can comprise the Uu interface, as standardized by 3GPP. Program memory 1220 can also comprise software code executed by processor 1210 to control the functions of network node 1200, including configuring and controlling various components such as radio network interface 1240 and core network interface 1250.

Data memory 1230 can comprise memory area for processor 1210 to store variables used in protocols, configuration, control, and other functions of network node 1200. As such, program memory 1220 and data memory 1230 can comprise non-volatile memory (e.g., flash memory, hard disk, etc.), volatile memory (e.g., static or dynamic RAM), network-based (e.g., “cloud”) storage, or a combination thereof. Persons of ordinary skill in the art will recognize that processor 1210 can include multiple individual processors (not shown), each of which implements a portion of the functionality described above. In such case, multiple individual processors may be commonly connected to program memory 1220 and data memory 1230 or individually connected to multiple individual program memories and/or data memories. More generally, persons of ordinary skill will recognize that various protocols and other functions of network node 1200 may be implemented in many different combinations of hardware and software including, but not limited to, application processors, signal processors, general-purpose processors, multi-core processors, ASICs, fixed digital circuitry, programmable digital circuitry, analog baseband circuitry, radio-frequency circuitry, software, firmware, and middleware.

Radio network interface 1240 can comprise transmitters, receivers, signal processors, ASICs, antennas, beamforming units, and other circuitry that enables network node 1200 to communicate with other equipment such as, in some embodiments, a plurality of compatible user equipment (UE). In some embodiments, interface 1240 can also enable network node 1200 to communicate with compatible satellites of a satellite communication network. In some exemplary embodiments, radio network interface 1240 can comprise various protocols or protocol layers, such as the PHY, MAC, RLC, PDCP, and/or RRC layer protocols standardized by 3GPP for LTE, LTE-A, LTE-LAA, NR, NR-U, etc. ; improvements thereto such as described herein above; or any other higher-layer protocols utilized in conjunction with radio network interface 1240. According to further exemplary embodiments of the present disclosure, the radio network interface 1240 can comprise a PHY layer based on OFDM, OFDMA, and/or SC-FDMA technologies. In some embodiments, the functionality of such a PHY layer can be provided cooperatively by radio network interface 1240 and processor 1210 (including program code in memory 1220).

Core network interface 1250 can comprise transmitters, receivers, and other circuitry that enables network node 1200 to communicate with other equipment in a core network such as, in some embodiments, circuit-switched (CS) and/or packet-switched Core (PS) networks. In some embodiments, core network interface 1250 can comprise the SI interface standardized by 3GPP. In some embodiments, core network interface 1250 can comprise the NG interface standardized by 3GPP. In some exemplary embodiments, core network interface 1250 can comprise one or more interfaces to one or more AMFs, SMFs, SGWs, MMEs, SGSNs, GGSNs, and other physical devices that comprise functionality found in GERAN, UTRAN, EPC, 5GC, and CDMA2000 core networks that are known to persons of ordinary skill in the art. In some embodiments, these one or more interfaces may be multiplexed together on a single physical interface. In some embodiments, lower layers of core network interface 1250 can comprise one or more of asynchronous transfer mode (ATM), Internet Protocol (IP)-over-Ethernet, SDH over optical fiber, T1/E1/PDH over a copper wire, microwave radio, or other wired or wireless transmission technologies known to those of ordinary skill in the art.

In some embodiments, network node 1200 can include hardware and/or software that configures and/or facilitates network node 1200 to communicate with other network nodes in a RAN, such as with other eNBs, gNBs, ng-eNBs, en-gNBs, IAB nodes, etc. Such hardware and/or software can be part of radio network interface 1240 and/or core network interface 1250, or it can be a separate functional unit (not shown). For example, such hardware and/or software can configure and/or facilitate network node 1200 to communicate with other RAN nodes via the X2 or Xn interfaces, as standardized by 3GPP.

OA&M interface 1260 can comprise transmitters, receivers, and other circuitry that enables network node 1200 to communicate with external networks, computers, databases, and the like for purposes of operations, administration, and maintenance of network node 1200 or other network equipment operably connected thereto. Lower layers of OA&M interface 1260 can comprise one or more of asynchronous transfer mode (ATM), Internet Protocol (IP)-over- Ethernet, SDH over optical fiber, T1/E1/PDH over a copper wire, microwave radio, or other wired or wireless transmission technologies known to those of ordinary skill in the art. Moreover, in some embodiments, one or more of radio network interface 1240, core network interface 1250, and OA&M interface 1260 may be multiplexed together on a single physical interface, such as the examples listed above.

Figure 13 is a block diagram of an exemplary communication network configured to provide over-the-top (OTT) data services between a host computer and a user equipment (UE), according to one or more exemplary embodiments of the present disclosure. UE 1310 can communicate with radio access network (RAN) 1330 over radio interface 1320, which can be based on protocols described above including, e.g., LTE, LTE-A, and 5G/NR. For example, UE 1310 can be configured and/or arranged as shown in other figures discussed above.

RAN 1330 can include one or more network nodes (e.g., base stations, eNBs, gNBs, controllers, etc.) operable in licensed spectrum bands, as well one or more network nodes operable in unlicensed spectrum (using, e.g., LAA or NR-U technology), such as a 2.4-GHz band and/or a 5-GHz band. In such cases, the network nodes comprising RAN 1330 can cooperatively operate using licensed and unlicensed spectrum. In some embodiments, RAN 1330 can include, or be capable of communication with, one or more satellites comprising a satellite access network.

RAN 1330 can further communicate with core network 1340 according to various protocols and interfaces described above. For example, one or more apparatus e.g., base stations, eNBs, gNBs, ng-eNBs, etc.) comprising RAN 1330 can communicate to core network 1340 via core network interface 1350 described above. In some exemplary embodiments, RAN 1330 and core network 1340 can be configured and/or arranged as shown in other figures discussed above. For example, eNBs comprising an evolved UTRAN (E-UTRAN) 1330 can communicate with an evolved packet core (EPC) network 1340 via an SI interface. As another example, gNBs and ng- eNBs comprising an NG-RAN 1330 can communicate with a 5GC network 1330 via an NG interface.

Core network 1340 can further communicate with an external packet data network, illustrated in Figure 13 as Internet 1350, according to various protocols and interfaces known to persons of ordinary skill in the art. Many other devices and/or networks can also connect to and communicate via Internet 1350, such as exemplary host computer 1360. In some exemplary embodiments, host computer 1360 can communicate with UE 1310 using Internet 1350, core network 1340, and RAN 1330 as intermediaries. Host computer 1360 can be a server (e.g., an application server) under ownership and/or control of a service provider. Host computer 1360 can be operated by the OTT service provider or by another entity on the service provider’s behalf.

For example, host computer 1360 can provide an over-the-top (OTT) packet data service to UE 1310 using facilities of core network 1340 and RAN 1330, which can be unaware of the routing of an outgoing/incoming communication to/from host computer 1360. Similarly, host computer 1360 can be unaware of routing of a transmission from the host computer to the UE, e.g., the routing of the transmission through RAN 1330. Various OTT services can be provided using the exemplary configuration shown in Figure 13 including, e.g., streaming (unidirectional) audio and/or video from host computer to UE, interactive (bidirectional) audio and/or video between host computer and UE, interactive messaging or social communication, interactive virtual or augmented reality, cloud gaming, etc.

The exemplary network shown in Figure 13 can also include measurement procedures and/or sensors that monitor network performance metrics including data rate, latency and other factors that are improved by exemplary embodiments disclosed herein. The exemplary network can also include functionality for reconfiguring the link between the endpoints (e.g., host computer and UE) in response to variations in the measurement results. Such procedures and functionalities are known and practiced; if the network hides or abstracts the radio interface from the OTT service provider, measurements can be facilitated by proprietary signaling between the UE and the host computer.

Embodiments described herein provide amplitude tapering techniques for beam-based transmission that are more efficient than conventional techniques, which generate overly- restrictive beams having low sidelobes in many different orientations rather than only in orientations of co-scheduled layers. Additionally, embodiments waste less transmit power due to sidelobe suppression, such that more transmit power is available for the main lobes of concurrent beams. Embodiments also provide flexible tradeoffs between sidelobe suppression and main lobe power based on a configurable interference threshold. Furthermore, beamforming vector codebooks can be kept relatively small since they are only required to include beam weights for individual orientations/users (e.g., SU-MIMO).

When used in NR gNBs e.g., gNBs comprising RAN 1330), embodiments can improve performance of multi-user MIMO transmission, thereby increasing coverage and/or downlink capacity in a cell. When used in NR UEs (e.g., UE 1310), embodiments can improve uplink coverage, which is often limited due to output power restrictions. In this manner, embodiments can increase the use of OTT data services by providing better coverage and/or capacity for such data services. Consequently, this increases the benefits and/or value of OTT data services to end users and OTT service providers.

The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. Various exemplary embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art.

The term unit, as used herein, can have conventional meaning in the field of electronics, electrical devices and/or electronic devices and can include, for example, electrical and/or electronic circuitry, devices, modules, processors, memories, logic solid state and/or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and/or displaying functions, and so on, as such as those that are described herein.

Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.

As described herein, device and/or apparatus can be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device or apparatus, instead of being hardware implemented, be implemented as a software module such as a computer program or a computer program product comprising executable software code portions for execution or being run on a processor. Furthermore, functionality of a device or apparatus can be implemented by any combination of hardware and software. A device or apparatus can also be regarded as an assembly of multiple devices and/or apparatuses, whether functionally in cooperation with or independently of each other. Moreover, devices and apparatuses can be implemented in a distributed fashion throughout a system, so long as the functionality of the device or apparatus is preserved. Such and similar principles are considered as known to a skilled person.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In addition, certain terms used in the present disclosure, including the specification and drawings, can be used synonymously in certain instances (e.g., “data” and “information”). It should be understood, that although these terms (and/or other terms that can be synonymous to one another) can be used synonymously herein, there can be instances when such words can be intended to not be used synonymously. Further, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly incorporated herein in its entirety. All publications referenced are incorporated herein by reference in their entireties.

Claims

1. A method of beamforming using an antenna array, the method performed by a node of a wireless network and comprising: for each pair of beamforming vectors (bk, bl) of a codebook (B) comprising a plurality of beamforming vectors (bl ... bN) corresponding to a respective plurality of orientations (1 . . . N), determining (910) at least one corresponding pair of real- valued tapering vectors (tk, tl) such that when tapered beamforming vectors (tk-bk, tl-bl) are applied to portions of the antenna array for concurrent transmission of beams of orientations (1 < k < N, 1 < Z < N, k Z), radiated power of the antenna array is maximized subject to the beams of orientations (k, Z) having sidelobes that are lower than associated thresholds (5k, 51) in respective orientations (Z, k); and transmitting (930) data concurrently in orientations (1 < i < N, 1 < j < N, i j) based on weighting the portions of the antenna array by the tapered beamforming vectors (ti-bi, tj-bj) corresponding to the orientations (z, j).

2. The method of claim 1 , wherein: each beamforming vector (bl ... bN) and each tapering vector (tk, tl) comprises M values corresponding to respective M portions of the antenna array; and the data is transmitted via respective power amplifiers (PA-1 . . . PA-M) coupled to the M portions of the antenna array.

3. The method of claim 2, wherein N is an integer multiple of M.

4. The method of any of claims 2-3, wherein each corresponding pair of real- valued tapering vectors (tk, tl) is further determined such that the M values of each tapering vector (tk, tl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers.

5. The method of any of claims 2-3, wherein each corresponding pair of real- valued tapering vectors (tk, tl) is further determined such that the M values of each tapered beamforming vectors (tk-bk, tl-bl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers.

6. The method of any of claims 2-3, wherein: each corresponding pair of real- valued tapering vectors (tk, tl) is further determined such that the M values of (a-tk + p-tl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers; and a > 0, P > 0, and a + P = 1.

7. The method of any of claims 2-6, wherein: each of the M values of each tapering vector is from the set (vl . . . vR), where R = 2^r; and determining (910) at least one corresponding pair of real-valued tapering vectors (tk, tl) for each pair of beamforming vectors (bk, bl) comprises: evaluating (911) radiated power and sidelobes of respective pairs of candidate tapering vectors having different combinations of M values selected from the set (vl ... vR); and selecting (912), as (tk, tl), the pair of candidate tapering vectors that maximizes radiated power subject to the sidelobes being lower than the respective thresholds (5k, 51) in orientations (Z, k).

8. The method of claim 7, wherein r is less than or equal to 6.

9. The method of any of claims 2-8, wherein the M portions of the antenna array are one of the following: M antenna elements; or M antenna sub-arrays, each sub-array including a plurality of antenna elements.

10. The method of any of claims 1-9, wherein the method further comprises forming (920) a codebook (T) comprising a plurality of entries indicating respective pairs of tapering vectors (tk, tl) determined for orientations (k, Z), 1 < k < N, 1 < I < N, k I.

11. The method of claim 10, wherein transmitting (930) data concurrently in orientations (z, j) comprises: selecting (931) an entry in codebook (T) that corresponds to the orientations

selecting (932) entries from codebook (B) that correspond to the orientations

and forming (933) the tapered beamforming vectors (ti-bi, tj-bj) based on the selected entry from codebook (T) and the selected entries from codebook (B).

12. The method of any of claims 1-11, wherein the thresholds (5k, 51) associated with the beams of orientations (k, Z) are -25 dB relative to the power of the beams of orientations (Z, k).

13. The method of any of claims 1-11, wherein: determining (910) at least one pair of real-valued tapering vectors (tk, tl) for the beams of orientations (k, Z) comprises: determining (913) a first pair of real-value tapering vectors (tk- 1 , tl- 1) based on first thresholds (5k- 1, 51-1) corresponding to first modulation and coding schemes (MCSk-1, MCS1-1) for the beams of orientations (k, Z); and determining (914) a second pair of real-value tapering vectors (tk-2, tl-2) based on second thresholds (5k-2, 51-2) corresponding to second modulation and coding schemes (MCSk-2, MCS1-2) for the beams of orientations (k, Z); and transmitting (930) the data concurrently in orientations (i, j) comprises selecting (931), as (ti, tj), either the first pair of tapering vectors (ti-1, tj-1) or the second pair of tapering vectors (ti-2, tj-2) based on modulation and coding schemes (MCSi, MCSj) used for the data carried by the beams of orientations (z, /).

14. The method of any of claims 1-13, wherein the node is one of the following: a network node in the wireless network, or a user equipment.

15. A node (1005, 1010, 1020, 1100, 1200, 1310) in a wireless network (1099, 1330), the node comprising: an antenna array (144, 1140, 1240) comprising a plurality of elements; transmitting circuitry (142, 1140, 1240) operably coupled to the antenna array; and processing circuitry (110, 1110, 1210) operably coupled to the transmitting circuitry and the antenna array, the processing circuitry being configured to cause the node to: for each pair of beamforming vectors (bk, bl) of a codebook (B) comprising a plurality of beamforming vectors (bl ... bN) corresponding to a respective plurality of orientations (1 . . . N), determine at least one corresponding pair of real-valued tapering vectors (tk, tl) such that when tapered beamforming vectors (tk-bk, tl-bl) are applied to portions of the antenna array for concurrent transmission of beams of orientations (1 < k < N, 1 < I < N, k Z), radiated power of the antenna array is maximized subject to the beams of orientations (k, Z) having sidelobes that are lower than associated thresholds (5k, 51) in respective orientations (Z, k); and transmit data concurrently in orientations (1 < i < N, 1 <j < N, i ^j) based on weighting the portions of the antenna array by the tapered beamforming vectors (ti-bi, tj-bj) corresponding to the orientations (z, /).

16. The node of claim 15, wherein: each beamforming vector (bl ... bN) and each tapering vector (tk, tl) comprises M values corresponding to respective M portions of the antenna array; and the data is transmitted via respective power amplifiers (PA-1 . . . PA-M) coupled to the M portions of the antenna array.

17. The node of claim 16, wherein N is an integer multiple of M.

18. The node of any of claims 16-17, wherein each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of each tapering vector (tk, tl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers.

19. The node of any of claims 16-17, wherein each corresponding pair of real-valued tapering vectors (tk, tl) is further determined such that the M values of each tapered beamforming vectors (tk-bk, tl-bl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers.

20. The node of any of claims 16-17, wherein: each corresponding pair of real- valued tapering vectors (tk, tl) is further determined such that the M values of (a-tk + p-tl) are less than or equal to respective maximum output powers (pl ... pM) of the power amplifiers; and a > 0, P > 0, and a + P = 1.

21. The node of any of claims 16-20, wherein: each of the M values of each tapering vector is from the set (vl . . . vR), where R = 2^r; and the processing circuitry is configured to cause the node to determine at least one corresponding pair of real-valued tapering vectors (tk, tl) for each pair of beamforming vectors (bk, bl) based on: evaluating radiated power and sidelobes of respective pairs of candidate tapering vectors having different combinations of M values selected from the set (vl ... vR); and selecting, as (tk, tl), the pair of candidate tapering vectors that maximizes radiated power subject to the sidelobes being lower than the respective thresholds (5k, 51) in orientations (Z, k).

22. The node of claim 21, wherein r is less than or equal to 6.

23. The node of any of claims 16-22, wherein the M portions of the antenna array are one of the following: M antenna elements; or M antenna sub-arrays, each sub-array including a plurality of antenna elements.

24. The node of any of claims 15-23, wherein the processing circuitry is further configured to cause the node to form a codebook (T) comprising a plurality of entries indicating respective pairs of tapering vectors (tk, tl) determined for orientations (k, Z), 1 < k < N, 1 < I < N, k I.

25. The node of claim 24, wherein the processing circuitry is configured to cause the node to transmit data concurrently in orientations (z, j) based on: selecting an entry in codebook (T) that corresponds to the orientations

selecting entries from codebook (B) that correspond to the orientations

and forming the tapered beamforming vectors (ti-bi, tj-bj) based on the selected entry from codebook (T) and the selected entries from codebook (B).

26. The node of any of claims 15-25, wherein the thresholds (5k, 51) associated with the beams of orientations (k, Z) are -25 dB relative to the power of the beams of orientations (Z, k).

27. The node of any of claims 15-25, wherein the processing circuitry is configured to cause the node to: determine at least one pair of real-valued tapering vectors (tk, tl) for the beams of orientations (k, Z) based on: determining a first pair of real-value tapering vectors (tk-1, tl-1) based on first thresholds (5k- 1, 51-1) corresponding to first modulation and coding schemes (MCSk-1, MCS1-1) for the beams of orientations (k, Z); and determining a second pair of real-value tapering vectors (tk-2, tl-2) based on second thresholds (5k-2, 51-2) corresponding to second modulation and coding schemes (MCSk-2, MCS1-2) for the beams of orientations (k, Z); and transmit the data concurrently in orientations (i, j) based on selecting, as (ti, tj), either the first pair of tapering vectors (ti- 1 , tj- 1) or the second pair of tapering vectors (ti-2, tj-2) based on modulation and coding schemes (MCSi, MCSj) used for the data carried by the beams of orientations (z, /).

28. The node of any of claims 15-27, wherein the node is one of the following: a network node in the wireless network, or a user equipment.

29. A node (1005, 1010, 1020, 1100, 1200, 1310) in a wireless network (1099, 1330), the node being configured for beamforming using an antenna array (144, 1140, 1240) and being further configured to: for each pair of beamforming vectors (bk, bl) of a codebook (B) comprising a plurality of beamforming vectors (bl ... bN) corresponding to a respective plurality of orientations (1 . . . N), determine at least one corresponding pair of real-valued tapering vectors (tk, tl) such that when tapered beamforming vectors (tk-bk, tl-bl) are applied to portions of the antenna array for concurrent transmission of beams of orientations (1 < k < N, 1 < I < N, k Z), radiated power of the antenna array is maximized subject to the beams of orientations (k, Z) having sidelobes that are lower than associated thresholds (5k, 51) in respective orientations (Z, k); and transmit data concurrently in orientations (1 < i < N, 1 < j < N, i ^j) based on weighting the portions of the antenna array by the tapered beamforming vectors (ti-bi, tj-bj) corresponding to the orientations (/, /).

30. The node of claim 29, being further configured to perform operations corresponding to any of the methods of claims 2-14.

31. A non-transitory, computer-readable medium (1120, 1220) storing computer-executable instructions that, when executed by processing circuitry (110, 1110, 1210) of a node (1005, 1010, 1020, 1100, 1200, 1310), in a wireless network (1099, 1330), that is configured for beamforming using an antenna array, configure the node to perform operations corresponding to any of the methods of claims 1-14.

32. A computer program product (1121, 1221) comprising computer-executable instructions that, when executed by processing circuitry (110, 1110, 1210) of a node (1005, 1010, 1020, 1100, 1200, 1310), in a wireless network (1099, 1330), that is configured for beamforming using an antenna array, configure the node to perform operations corresponding to any of the methods of claims 1-14.