HK40085271A - Mitigation of calibration errors - Google Patents

Description

Mitigation of calibration errors

The present application is a divisional application of the invention patent application with application number 201880072454.6 entitled "method and apparatus for wireless communication" on application day 2018, 11, 8.

Priority is required in accordance with 35 U.S. c. ≡119

The present application claims priority and benefit from U.S. non-provisional application No. 16/138,880, entitled "MITIGATION OF CALIBRATION ERRORS," filed on date 21 at 9 and 2018, which is assigned to the assignee of the present application and hereby expressly incorporated by reference herein.

Technical Field

The present application relates to wireless communication systems, and more particularly, to improving transmission performance by mitigating calibration errors at a base station. Embodiments implement and provide solutions and techniques for improving calibration accuracy.

Background

The wireless communication network may include a plurality of Base Stations (BSs) that may support communication for a plurality of User Equipments (UEs). In Long Term Evolution (LTE), a BS is called an evolved node B (eNB). In recent years, carrier frequencies at which BSs and UEs communicate continue to increase and include greater bandwidths. To take advantage of these higher frequencies, more antennas have been used in the same physical aperture. However, in order for these higher frequency bands to be useful and to approximate the same coverage radius as the prior art (such as 2G, 3G, or 4G), a larger beamforming gain (and more accurate) beamforming transmission is required.

Reciprocity describes the ability of a wireless device to use information (such as angle of arrival and delay) from one channel (e.g., DL) to make a determination about another channel (e.g., UL). In a Time Division Duplex (TDD) system, after circuit mismatch has been compensated, the physical UL channel and the physical DL channel are identical (or transposes of each other from a matrix algebraic point of view) because UL and DL operate in the same frequency band. For example, the BS may calculate UL channel estimates based on UL reference signals, such as Sounding Reference Signals (SRS) transmitted by the UE, and use the UL channel estimates for DL beamforming. In another example, the UE may calculate DL channel estimation based on a Secondary Synchronization Block (SSB) or channel state information-reference signal (CSI-RS) transmission transmitted from the BS and use the information for UL channel estimation in UL transmission. In practice, however, the communication channel between a pair of nodes (e.g., BS and UE) includes not only physical channels, but also Radio Frequency (RF) transceiver chains, including, for example, antennas, low Noise Amplifiers (LNAs), mixers, RF filters and analog-to-digital (a/D) or digital-to-analog (D/a) converters, and in-phase-quadrature-phase (I/Q) imbalances, which may differ between different nodes and/or different antennas. Thus, each node may introduce a mismatch to the transmitted and/or received signal, e.g., in amplitude and/or phase. Mismatch may affect the performance of channel reciprocity based transmissions.

Disclosure of Invention

In order to provide a basic understanding of the technology in question, some aspects of the disclosure are summarized below. This summary is not an extensive overview of all contemplated features of the disclosure, nor is it intended to identify key or critical elements of all aspects of the disclosure or to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

Embodiments of the present disclosure provide mechanisms for mitigating calibration errors. Implementation may occur from both a network perspective (e.g., on the Base Station (BS) side) or a non-network perspective (e.g., UE, relay, node, etc.). Calibration is the process of ensuring that the phase and amplitude at each antenna replicate the desired response at a particular excitation. Without calibration, the receive beam weights may not yield the expected correct behavior. Calibration helps correct phase and amplitude mismatch between the transmit and receive circuits (e.g., due to mismatch in amplifiers, mixers, filters, couplers, etc.). The transmit and receive beam weights are typically assumed to be reciprocal. Thus, without calibration, the receive beam weights may not be reused for transmission. Mitigation of phase and amplitude calibration errors may involve modifying the array size, transmit power level and/or beam codebook at the BS side.

For example, in one aspect of the disclosure, a method of wireless communication includes: transmitting, by the base station, a first communication signal via an antenna array comprising a plurality of antenna elements using a first number of the plurality of antenna elements and a first transmit power level; receiving, by the base station, a measurement report based on the first communication signal from at least one user equipment; and transmitting, by the base station, a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report, wherein at least one of: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level.

In an additional aspect of the disclosure, an apparatus includes a transceiver configured to: transmitting, by the base station, a first communication signal using a first number of the plurality of antenna elements and a first transmit power level via an antenna array comprising the plurality of antenna elements; receiving, by the base station, a measurement report based on the first communication signal from at least one user equipment; and transmitting, by the base station, a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report, wherein at least one of: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level.

In an additional aspect of the present disclosure, a computer readable medium having program code recorded thereon, the program code comprising: transmitting, via an antenna array comprising a plurality of antenna elements, a first communication signal using a first number of the plurality of antenna elements and a first transmit power level; code for receiving a measurement report based on the first communication signal from at least one user equipment; and means for transmitting a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report, wherein at least one of: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level.

In an additional aspect of the disclosure, an apparatus includes: transmitting a first communication signal using a first number of the plurality of antenna elements and a first transmit power level; means for receiving a measurement report based on the first communication signal from at least one user equipment; and means for transmitting a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report, wherein at least one of the following holds: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level.

In some examples, in an aspect of the disclosure, a method of wireless communication includes: receiving, by the user equipment, a first communication signal from the base station; transmitting, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and receiving, by the user equipment, a second communication signal from the base station in response to the request.

In an additional aspect of the disclosure, an apparatus includes a transceiver configured to: receiving, by the user equipment, a first communication signal from the base station; transmitting, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and receiving, by the user equipment, a second communication signal from the base station in response to the request.

In an additional aspect of the present disclosure, a computer readable medium having program code recorded thereon, the program code comprising: code for receiving, by a user equipment, a first communication signal from a base station; means for transmitting, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and code for receiving, by the user equipment, a second communication signal from the base station in response to the request.

In an additional aspect of the disclosure, an apparatus includes: means for receiving a first communication signal from a base station; means for sending, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and means for receiving a second communication signal from the base station in response to the request.

Other aspects, features and embodiments of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific, exemplary embodiments in conjunction with the accompanying figures. Although features are discussed with respect to certain embodiments and figures below, all embodiments may include one or more of the advantageous features discussed herein. In other words, while one or more embodiments are discussed as having certain advantageous features, one or more of these features may also be used in accordance with the various embodiments discussed herein. In a similar manner, while exemplary embodiments are discussed below as device, system, or method embodiments, it should be understood that these exemplary embodiments can be implemented with a wide variety of devices, systems, and methods.

Drawings

Fig. 1 illustrates a wireless communication network according to some embodiments of the present disclosure.

Fig. 2 illustrates a communication method according to some embodiments of the present disclosure.

Fig. 3 illustrates a communication method according to some embodiments of the present disclosure.

Fig. 4 is a block diagram of an exemplary Base Station (BS) according to an embodiment of the present disclosure.

Fig. 5 is a block diagram of an exemplary User Equipment (UE) in accordance with an embodiment of the present disclosure.

Fig. 6 illustrates a signaling diagram of a method for mitigating calibration errors, according to some embodiments of the present disclosure.

Fig. 7 is a flow chart of a communication method according to an embodiment of the present disclosure.

Fig. 8 is a flow chart of a communication method according to an embodiment of the present disclosure.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations only and is not intended to represent the concepts described herein as being implemented in only those configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. It will be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

The present disclosure relates generally to providing or participating in authorized shared access between two or more wireless communication systems (also referred to as wireless communication networks). In various embodiments, the techniques and apparatus may be used for wireless communication networks such as the following, as well as other communication networks: code Division Multiple Access (CDMA) networks, time Division Multiple Access (TDMA) networks, frequency Division Multiple Access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, fifth generation (5G) or New Radio (NR) networks. As described herein, the terms "network" and "system" may be used interchangeably.

An OFDMA network may implement radio technologies such as evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM, and the like. UTRA, E-UTRA and global system for mobile communications (GSM) are part of Universal Mobile Telecommunications System (UMTS). In particular, long Term Evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named "third generation partnership project" (3 GPP), and cdma2000 is described in documents from an organization named "third generation partnership project 2" (3 GPP 2). These various radio technologies and standards are known or under development. For example, the third generation partnership project (3 GPP) is a collaboration between groups of telecommunications associations that are targeted to define the globally applicable third generation (3G) mobile phone specifications. 3GPP Long Term Evolution (LTE) is a 3GPP project that aims at improving the Universal Mobile Telecommunications System (UMTS) mobile telephony standard. The 3GPP may define specifications for next generation mobile networks, mobile systems and mobile devices. The present disclosure relates to evolution from LTE, 4G, 5G, NR and beyond radio technologies with shared access to the radio spectrum between networks using some new and different radio access technologies or radio air interfaces.

In particular, 5G networks contemplate a wide variety of deployments, a wide variety of spectrum, and a wide variety of services and devices that may be implemented using a unified air interface based on OFDM. To achieve these goals, further enhancements to LTE and LTE-a are considered in addition to the development of new radio technologies for 5G NR networks. The 5G NR will be able to scale (1) to provide coverage to large-scale internet of things (IoT) with ultra-high density (e.g., -1M nodes/km 2), ultra-low complexity (e.g., -10 s bits/second), ultra-low energy (e.g., -10+ years of battery life), and to provide deep coverage with the ability to reach challenging sites; (2) Including mission critical controls with strong security for protecting sensitive personal, financial, or confidential information, ultra-high reliability (e.g., -99.9999% reliability), ultra-low latency (e.g., -1 ms), and users with a wide range of mobility or lack of mobility; and (3) enhanced mobile broadband including extremely high capacity (e.g., -10 Tbps/km 2), limited data rates (e.g., multiple Gbps rates, user experience rates of 100+mbps), and advanced discovery and optimized depth perception.

The 5G NR may be implemented to use an optimized OFDM-based waveform with a scalable digital scheme (numerology) and Transmission Time Interval (TTI); has a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency Time Division Duplex (TDD)/Frequency Division Duplex (FDD) design; and advanced wireless technologies such as massive Multiple Input Multiple Output (MIMO), robust millimeter wave (mm wave) transmission, advanced channel coding, and device-centric mobility. Scalability of the digital scheme in 5G NR (with scaling of sub-carrier spacing) can efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments with implementations of less than 3GHz FDD/TDD, the subcarrier spacing may occur at 15kHz, e.g., on BW of 1, 5, 10, 20MHz, etc. For other various outdoor and small cell coverage deployments of TDD greater than 3GHz, the subcarrier spacing may occur at 30kHz over 80/100MHz BW. For other various indoor wideband implementations, using TDD on the unlicensed portion of the 5GHz band, the subcarrier spacing may occur at 60kHz on 160MHz BW. Finally, for various deployments that transmit with millimeter wave components at TDD at 28GHz, the subcarrier spacing may occur at 120kHz over 500MHz BW.

The scalable digital scheme of 5G NR facilitates scalable TTI for different latency and quality of service (QoS) requirements. For example, shorter TTIs may be used for low latency and high reliability, while longer TTIs may be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmissions to start on symbol boundaries. The 5G NR also contemplates a self-contained integrated subframe design in which uplink/downlink scheduling information, data, and acknowledgements are in the same subframe. The self-contained integrated subframes support communication, adaptive uplink/downlink (which can be flexibly configured on a per cell basis to dynamically switch between uplink and downlink to meet current traffic demands) in unlicensed or contention-based shared spectrum.

Various other aspects and features of the disclosure are described further below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. Furthermore, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or both in addition to or other than one or more of the aspects set forth herein. For example, the methods may be implemented as part of a system, apparatus, device, and/or as instructions stored on a computer-readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of the claims.

The beam management operation is based on control messages periodically exchanged between the transmitter node and the receiver node. Beamforming may be used to bridge the link budget, which may be quite pessimistic at mm-wave frequencies due to severe propagation loss. The BS and the UE may use beams to transmit information and each of the BS and the UE may direct its energy in a particular direction, thereby obtaining array gain and bridging link budget in the process. Specifically, the BS transmits DL information using a beam, and the UE receives DL information using a beam. Subsequently, when the UE transmits UL information, the UE may set a beam weight corresponding to the same direction as the previously mentioned beam and transmit UL data with the same beam weight (assuming that it has reciprocity).

Beamforming may depend on the design of a good beamforming codebook. However, these codebooks can perform as designed when the amplitude and phase at the antenna are reasonably well calibrated. The BS may have a large number of antennas and near perfect amplitude and phase calibration may require a significant amount of time, complexity and effort. It may be desirable to mitigate phase and amplitude calibration errors at the BS.

The present disclosure provides techniques for mitigating phase and amplitude calibration errors in communications between a User Equipment (UE) and a Base Station (BS). DL and UL channels may lack reciprocity due to various factors. In the case of calibration, the adjusted beam weights may be used to receive and transmit data. Calibration is the process of ensuring that the phase and amplitude at each antenna replicate the desired response at a particular excitation. Without calibration, the receive beam weights may not yield the expected correct behavior. Calibration helps correct phase and amplitude mismatch between the transmit and receive circuits (e.g., due to mismatch in amplifiers, mixers, filters, couplers, etc.). The transmit and receive beam weights are typically assumed to be reciprocal. Thus, without calibration, the receive beam weights may not be reused for transmission.

While a per-antenna calibration may be performed, it can be very time consuming, complex, and require a large number of manual operations. Even if it is assumed that the performance is performed on a per-antenna basis, residual errors in phase and amplitude for each antenna (for example, time taken for measurement accuracy and calibration) may occur. Furthermore, with respect to time-varying calibration errors, calibration is typically performed on a per frequency/subcarrier and per temperature (value) basis. Due to complexity, only a limited number of points can be sampled across frequency and temperature. Once the operating frequency or number of component carriers is determined, the only change is from temperature drift. Due to the limited sampling, time-varying phase and amplitude calibration errors may occur.

Aspects of the technology discussed herein may provide several benefits. For example, mitigation of phase and/or amplitude calibration errors at the BS side may lead to better performance. The NR band may have high path loss and may not be as stable as the LTE band due to high frequencies. Thus, mitigation of phase and/or amplitude calibration errors may improve NR network coverage. These benefits and other features are recognized and discussed below.

Fig. 1 illustrates a wireless communication network 100 according to some embodiments of the present disclosure. Network 100 may be a 5G network. The network 100 includes a plurality of Base Stations (BSs) 105 and other network entities. BS 105 may be a station in communication with UE 115 and may also be referred to as an evolved node B (eNB), next generation eNB (gNB), access point, etc. Each BS 105 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to this particular geographic coverage area of BS 105 and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

BS 105 may provide communication coverage for a macrocell or a small cell (e.g., a picocell or a femtocell) and/or other types of cells. A macro cell typically covers a relatively large geographical area (e.g., a few kilometers in radius) and may allow unrestricted access by UEs with service subscription with the network provider. A small cell (e.g., a pico cell) will typically cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription with the network provider. A small cell (e.g., a femto cell) will also typically cover a relatively small geographic area (e.g., a home), and may provide limited access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.), in addition to unrestricted access. The BS for the macro cell may be referred to as a macro BS. The BS for the small cell may be referred to as a small cell BS, a pico BS, a femto BS, or a home BS. In the example shown in fig. 1, BSs 105D and 105e may be conventional macro BSs, and BSs 105a-105c may be macro BSs implemented with one of three-dimensional (3D), full-dimensional (FD), or massive MIMO. BSs 105a-105c may utilize their higher dimensional MIMO capabilities to utilize 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. BS 105f may be a small cell base station, which may be a home base station or a portable access point. BS 105 may support one or more (e.g., two, three, four, etc.) cells.

The network 100 may support synchronous operation or asynchronous operation. For synchronous operation, BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, BSs may have different frame timings, and transmissions from different BSs may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100, and each UE115 may be stationary or mobile. The UE115 may also be referred to as a terminal, mobile station, subscriber unit, station, etc. The UE115 may be a cellular telephone, a Personal Digital Assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless telephone, a Wireless Local Loop (WLL) station, etc. In one aspect, the UE115 may be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, the UE115 may be a device that does not include a UICC. In some aspects, a UE that does not include a UICC may also be referred to as a internet of everything (IoE) device. UEs 115a-115d are examples of mobile smart phone type devices that access network 100. UE115 may also be a machine specifically configured for connected communications, including Machine Type Communications (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT), etc. UEs 115e-115k are examples of various machines configured for communication with access network 100. The UE115 may be capable of communicating with any type of BS (whether macro BS, small cell, etc.). In fig. 1, lightning (e.g., a communication link) indicates wireless transmissions between the UE115 and the serving BS 105 (which is a BS designated to serve the UE115 on the downlink and/or uplink), desired transmissions between BSs, and backhaul transmissions between BSs.

In operation, BSs 105a-105c may use 3D beamforming and a collaborative space technique, such as coordinated multipoint (CoMP) or multi-connectivity, to serve UEs 115a and 115 b. The macro BS 105d may perform backhaul communications with BSs 105a-105c and small cell, BS 105 f. The macro BS 105d may also transmit multicast services that UEs 115c and 115d subscribe to and receive. Such multicast services may include mobile televisions or streaming video, or may include other services for providing community information, such as weather emergency or alerts (e.g., amber alerts or gray alerts).

The network 100 may also support mission critical communications that utilize ultra-reliable and redundant links for mission critical devices (e.g., the UE115 e, which may be a drone). The redundant communication links with UE115 e may include links from macro BSs 105d and 105e and links from small cell BS 105 f. Other machine type devices (e.g., UE115f (e.g., thermometer), UE115 g (e.g., smart meter), and UE115 h (e.g., wearable device)) may communicate directly with BSs (e.g., small cell BS 105f and macro BS 105 e) through network 100, or by communicating with another user device relaying its information to the network (e.g., UE115f transmits temperature measurement information to smart meter (UE 115 g), which is then reported to the network through small cell BS 105 f) in a multi-hop configuration. Network 100 may also provide additional network efficiency through dynamic, low latency TDD/FDD communications, such as in vehicle-to-vehicle (V2V).

In some implementations, the network 100 uses OFDM-based waveforms for communication. OFDM-based systems divide the system BW into a plurality (K) of orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, etc. Each subcarrier may be modulated with data. In some cases, the spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may depend on the system BW. The system BW may also be divided into sub-bands. In other cases, the subcarrier spacing and/or the duration of the TTI may be scalable.

In an embodiment, BS 105 may assign or schedule transmission resources (e.g., in the form of time-frequency Resource Blocks (RBs)) for Downlink (DL) and Uplink (UL) transmissions in network 100. DL refers to a transmission direction from BS 105 to UE 115, and UL refers to a transmission direction from UE 115 to BS 105. The communication may be in the form of a radio frame. The radio frame may be divided into a plurality of subframes, for example, about 10. Each subframe may be divided into slots, for example, approximately 2. Each time slot may be further divided into minislots. In Frequency Division Duplex (FDD) mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes UL subframes in the UL band and DL subframes in the DL band. In Time Division Duplex (TDD) mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of subframes in a radio frame (e.g., DL subframes) may be used for DL transmissions, while another subset of subframes in a radio frame (e.g., UL subframes) may be used for UL transmissions.

DL subframes and UL subframes may also be divided into several regions. For example, each DL or UL subframe may have predefined regions for transmission of reference signals, control information, and data. The reference signal is a predetermined signal that facilitates communication between the BS 105 and the UE 115. For example, the reference signal may have a particular pilot pattern or structure in which pilot tones may span the operational BW or band, each pilot tone being located at a predefined time and a predefined frequency. For example, BS 105 may transmit cell-specific reference signals (CRSs) and/or channel state information-reference signals (CSI-RSs) to enable UE115 to estimate DL channels. Similarly, UE115 may transmit Sounding Reference Signals (SRS) to enable BS 105 to estimate UL channels. The control information may include resource assignments and protocol control. The data may include protocol data and/or operational data. In some embodiments, BS 105 and UE115 may communicate using self-contained subframes. The self-contained subframe may include a portion for DL communication and a portion for UL communication. The self-contained subframes may be DL-centric or UL-centric. DL-centric sub-frames may comprise a longer duration for DL communication than UL communication. UL-centric subframes may include longer durations for UL communications than DL communications.

In some embodiments, BS 105 may coordinate with UEs 115 to cooperatively schedule, beamform, and/or transmit data in network 100. Substantial gain can be achieved by using more multi-antenna systems. For example, in mm wave access, a large number of antenna elements may be used to take advantage of shorter wavelengths and achieve beam forming and beam tracking. The higher the frequency, the greater the propagation and penetration losses may be.

Beamforming techniques may be used to increase the signal level received by the device and avoid transmission loss when using, for example, mm-wave frequencies. The beamformer boosts the energy in its target/intended direction, achieves a specific antenna gain in a given direction, and has attenuation in other directions. Beamforming combines signals from multiple antenna elements in an antenna array such that the combined signal level increases (constructive interference) when the multiple signals are phase aligned. Each antenna array may include a plurality of antenna elements. The signals from each antenna element are transmitted with slightly different phases (delays) to produce a narrow beam directed toward the receiver.

DL and UL channels may lack reciprocity for various reasons due to various factors. Example scenarios where DL and UL channels may lack reciprocity include using poor RF components on DL or UL, poor calibration efforts to adjust DL/UL circuitry, drift in component behavior over time, temperature, and other parameters, and the like. The calibration process may involve determining a nominal difference between DL and UL circuits.

While a per-antenna calibration may be performed, it can be very time consuming, complex, and require a large number of manual operations. Even if it is assumed to be performed on a per-antenna basis, residual errors in phase and amplitude for each antenna (e.g., due to measurement accuracy and time spent calibrating) may occur. Furthermore, with respect to time-varying calibration errors, calibration is typically performed on a per frequency/subcarrier and per temperature (value) basis. Due to complexity, only a limited number of points may be sampled across frequency and temperature. Once the operating frequency or number of common carriers is determined, the only change may be from temperature drift.

Due to the limited sampling, time-varying phase and amplitude calibration errors may occur. As far as phase calibration errors are concerned, it can reasonably be assumed that the phase at the ith antenna at any point in time satisfies the following equation:

wherein phi is _i The phase of the measurement is indicated and,represents the true phase, and ε _i Representing the phase error in the calibration.

The phase calibration error may be uniformly distributed in +/-q degrees according to the following equation:

ε _i ～∪(-q,q)， (2)

the phase calibration errors may be uniformly distributed with some small angular resolution of +/-q degrees. In one example, q is 5 °, which may be reasonable based on low calibration, but may result in an approximation error of +/-20 ° for low complexity calibration.

As far as the amplitude calibration error is concerned, it can reasonably be assumed that the amplitude at the ith antenna at any point in time satisfies the following equation:

wherein alpha is _i Representing the magnitude of the measurement and,represents the true amplitude, and θ _i Representing the amplitude calibration error in the calibration.

The amplitude calibration error may be uniformly distributed in +/-a amplitude units according to the following equation:

θ _i ～∪(-A,A)， (4)

the amplitude calibration errors may be evenly distributed with some small angular resolution of +/-a amplitude units.

In addition to phase and amplitude calibration errors, another impairment may involve failure of some portion of the antenna. Random antenna failure may occur, where for some indexes, alpha may be assumed _i Zero. In an example, if a certain percentage of antennas in a 32x4 antenna array on the BS side are dropped or failed (e.g., one, two, five, ten, fifteen, and twenty percent), the worst case performance may be significantly degraded. In this example, the minimum percentage drop may be one percent. If five percent of the antennas are discarded, the worst case gain in the coverage area may be from about-6 dB to about-15 dB. In an example, if an antenna is excluded from being used to transmit communication signals, the antenna is "discarded" thus reducing the number of antennas used to transmit communication signals. Conversely, if an antenna is included (and previously excluded) for transmitting a communication signal, the antenna is "added" thus increasing the number of antennas used for transmitting the communication signal. The array is reconfigured to obtain the best phase/amplitude or to compensate for phase/amplitude calibration errors for one or more beams in a particular sector.

Furthermore, the errors described above may be time-varying. For example, at one point in time, the error may be between +/-5 °, but if the array at BS105 heats up and the temperature drifts, the expected nominal temperature may drift by about 10 °. If the calibration is not performed using this actual temperature (but using the expected temperature), an error of +/-20 ° may occur. Further, if the size of the antenna array of BS105 is large, a large net accumulation due to the above-described impairments may occur.

The codebook includes beam weights for a set of beams covering the coverage area of the BS 105. The codebook may be pre-designed and the BS may apply a specific set of beam weights using the codebook to point to signals in a specific direction. For example, an array covering 120 ° azimuth and 50 ° elevation may use four beams. Each beam may include a set of beam weights applied to the antenna. The first beam may be directed in a first direction, the second beam may be directed in a second direction, the third beam may be directed in a third direction, and the fourth beam may be directed in a fourth direction. Each of the four beams covers a different area of the coverage area, and in particular, the BS may cover a 120 ° by 50 ° coverage area using the four beams. The delay associated with the initial acquisition, refinement, or other beamforming process may depend on the codebook size (e.g., four, eight, sixteen, thirty-two). The larger the codebook size, the finer the link may be, resulting in better beamforming gain.

Regarding the codebook, even a small phase calibration error +/-5 ° may result in severe worst-case gain degradation for small codebook sizes. In addition, moderate phase calibration errors +/-20 ° can lead to significant large performance degradation. Significant degradation in performance may be due to poor amplitude calibration or loss of a large number of antennas. The impact of the impairments on a smaller size codebook may be greater than for a larger size codebook because of the greater redundancy of beam weights in the larger size codebook. For example, for a codebook of size four, the worst-case gain over a coverage area of 120 ° x50 ° may be poor because a large array size is used to cover a large area with a small number of beams. For good coverage, latency can be reduced. If codebook entries of size four have uniformly distributed +/-5 deg. errors, the worst case Cumulative Distribution Function (CDF) of gains can range from about-5.5 to about-8 dB. If codebook entries of size four have uniformly distributed +/-25 deg. errors, the worst case gain can range from about-7 to about-15 dB. The larger the calibration error, the worse the performance may be in terms of worst case gain for the coverage area. The BS does not know where the UE may be located and may be interested in improving performance (even for worst case scenarios).

It may be desirable to mitigate phase and amplitude calibration errors at the BS. In some examples, the mitigation of phase and amplitude calibration errors may involve modifying the array size, transmit power level, and/or beam codebook at the BS side.

Fig. 2 illustrates a communication method 200 according to some embodiments of the present disclosure. As shown in diagram 200, input parameter set 202 and control input set 210 are associated with BS 205. The set of input parameters 202 and the set of control inputs 210 may be used to modify the antenna array size or codebook size used to transmit data. The set of input parameters 202 may include the size of the antenna array 204, the coverage area of the array 206, and the codebook size 208, among other input parameters. The set of control inputs 210 may include a maximum phase calibration error q212, a maximum amplitude calibration error a214, and an antenna loss portion 216, among other control inputs.

BS 205 includes a plurality of antenna elements 220. In an example, the plurality of antenna elements includes 128 antenna elements (32 x4 antenna array) and the codebook size is four. Codebook sizes of four are small and constrained compared to larger sizes (e.g., eight, sixteen, or thirty-two). The BS 204 may use a reduced size array (e.g., a 16x4 antenna array) to cover the same coverage area 206 and have the same codebook size 208 instead of using a 32x4 array. BS 205 may increase the transmit power to within the Effective Isotropic Radiated Power (EIRP)/Total Radiated Power (TRP) limit for transmission due to the peak array gain lost to the reduced antenna array size.

In an ideal case without phase calibration errors, the use of a 16x4 antenna array by BS 205 may be worse than the use of a 32x4 antenna array in terms of performance. However, by reducing the antenna array size from 32x4 to 16x4, performance may be more robust to phase calibration errors. For example, if BS 205 performs with a 32x4 array size with +/-10 ° error, using a 16x4 array size with the same +/-10 ° error may not result in the worst scene being too affected. In the presence of phase calibration errors, the 16x4 antenna array provides better performance than the 32x4 antenna array, improving by 3dB. In this example, the peak power for the two arrays may match, but the 16x4 antenna array provides more robustness to the worst case power scenario.

If BS 205 uses a codebook of smaller size, the design may not provide robustness to phase and amplitude calibration errors. If BS 205 uses a large array, multiple antennas from that array may not be used (e.g., 50% of the antennas), resulting in a loss of 3dB in terms of peak array gain. Losses can be compensated by increasing EIRP by 3dB so that the net power steering in a particular direction remains unchanged.

BS205 may receive feedback 230 from one or more UEs 215 to determine whether to modify the antenna array size and/or the power transmission level. Modifications may occur to support changing the effective array size (e.g., for widened beams). Feedback 230 may be an indication that BS205 is modifying the first number and the first transmit power level for subsequent signaling. Feedback 230 from one or more UEs may direct BS205 to determine whether to modify the number of antenna elements and/or transmit power level for future signal transmissions. In an example, feedback 230 is a measurement report including at least one of: reference Signal Received Power (RSRP), reference Signal Received Quality (RSRQ), received Signal Strength Indicator (RSSI), signal to interference plus noise ratio (SINR), or signal to noise ratio (SNR) from one or more UEs 215. It may be advantageous to have the UE provide this type of information in the measurement report sent to the BS, as it provides the BS with empirical feedback of the UE. For example, if the BS is provided with an indication (via measurement reports) that multiple UEs are experiencing poor RSRP levels, the BS may determine that the poor performance is due to phase and/or amplitude calibration errors. To mitigate these calibration errors, the BS may modify the array size and/or transmit power level for future signal transmissions.

Referring to fig. 2, bs 205 may have sufficient processing power to determine mitigation strategy 240. The mitigation strategy may include determining whether to modify the array size and transmit power level for future signaling. In this example, the BS may modify the transmit power level and the array size based on feedback from one or more UEs (e.g., by decreasing the array size and increasing the transmit power level if the error estimate is large, or by increasing the array size and decreasing the transmit power level if the error estimate is small).

The BS may modify the transmit power level and array size based on an aggregation of power reports (e.g., UE action requests and phase/amplitude calibration error information) for multiple UEs. The BS may adjust/refine the codebook based on the feedback. For example, the BS may change from using a codebook of size four to a codebook of size eight or sixteen. Using information from UEs in the coverage area, the BS may perform codebook adjustments at the BS. Thus, codebook changes may be accomplished according to information contained in the aggregated UE report. If the net performance at the UE increases, the BS codebook adjustment is in the correct direction and the process iterates to improve the codebook. In addition, the BS may utilize built-in test patterns (e.g., on-line/mission mode calibration or self-test) to improve calibration accuracy.

The self-test may include checking the operating characteristics and adjusting the antenna array usage parameters based on the checked self-test results. By performing the self-test, the BS may improve the operation performance or perform according to desired network design conditions. The self-test details may be stored in memory at the BS and/or updated periodically as needed throughout operation.

Fig. 3 illustrates a communication method 300 according to some embodiments of the present disclosure. Fig. 3 includes BS 205, input parameter set 202, and control input set 210.BS 205 is coupled to transmission point 302 via link 304. The transmission point 302 includes a plurality of antenna elements 220. In some examples, link 304 is a fiber optic link between a BS and transmission point 302. BS 205 may forward feedback 230 from one or more UEs to transmission point 302.

Referring to fig. 3, bs 205 may not have computational intelligence. For example, the BS may be small and a large antenna array (e.g., 32x 4) may not fit into the BS. In this example, the BS may forward feedback (e.g., measurement reports) from the UE and instantaneous information about phase and/or amplitude calibration errors (e.g., temperature estimates and look-up tables for calibrating interpolation errors) to the transmission point (e.g., server). The transmission point 302 processes the information forwarded by the BS and feeds back the mitigation strategy 240 to the BS. Although not shown, the transmission point 302 may be used by one or more BSs to mitigate amplitude and phase calibration errors. The transmission point 302 may be, for example, a server, a network-level device, or other device.

In some examples, if enough UEs report a power metric (e.g., RSRP, RSRQ, RSSI, SINR or SNR) below a certain threshold, the BS may modify the array size and transmit power level (e.g., by decreasing the array size and increasing the transmit power level, or by increasing the array size and decreasing the transmit power to improve the worst-case coverage of the BS). In some examples, the transmission point may suggest codebook adjustments (e.g., increasing or decreasing codebook size) or refinements. In some examples, the transmission point utilizes a built-in test mode (e.g., online mode/mission mode calibration) to improve calibration accuracy.

Fig. 4 is a block diagram of an exemplary BS 400 in accordance with some aspects of the present disclosure. For example, BS 400 may be BS 105 discussed above. As shown, BS 400 may include a processor 402, a memory 404, a calibration module 408, a reporting module 409, a transceiver 410 including a modem subsystem 412 and an RF unit 414, and one or more antennas 416. These elements may communicate with each other directly or indirectly, for example, via one or more buses.

The processor 402 may have various features such as a type-specific processor. For example, these may include CPU, DSP, ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. Processor 402 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Memory 404 may include cache memory (e.g., of processor 402), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid state memory devices, one or more hard drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some embodiments, memory 404 includes a non-transitory computer-readable medium. Memory 404 may store instructions 406. The instructions 406 may include: the instructions, when executed by the processor 402, cause the processor 402 to perform the operations described herein. The instructions 406 may also be referred to as code. The terms "instructions" and "code" should be construed broadly to include any type of computer-readable statement. For example, the terms "instructions" and "code" may refer to one or more programs, routines, subroutines, functions, procedures, and the like. The "instructions" and "code" may comprise a single computer-readable statement or a plurality of computer-readable statements.

Each of the calibration module 408 and the reporting module 409 may be implemented via hardware, software, or a combination thereof. For example, each of the calibration module 408 and the reporting module 409 may be implemented as a processor, circuitry, and/or instructions 406 stored in the memory 404 and executed by the processor 402.

Each of the calibration module 408 and the reporting module 409 may be used for various aspects of the present disclosure. For example, the calibration module 408 may be configured to transmit the first communication signal using a first number of the plurality of antenna elements and the first transmit power level via an antenna array comprising the plurality of antenna elements. The reporting module 409 may be configured to receive a measurement report based on the first communication signal from the at least one UE. The calibration module 408 may perform calibration for mismatch based on the measurement report. For example, the calibration module 408 may increase the number of antenna elements and decrease the transmit power level for future communication signal transmissions. In another example, the calibration module 408 may reduce the number of antenna elements and increase the transmit power level for future communication signal transmissions.

The calibration module 408 may be further configured to transmit a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report. At least one of the following holds true: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level. The calibration module 408 may also be configured to: the method includes transmitting a first communication signal beam, a beam codebook, adjusting or refining the beam codebook based on a measurement report, and transmitting a second communication signal based on the adjusted beam codebook. Mechanisms for mitigating phase and amplitude calibration errors for communications between a BS and a UE are described in more detail herein.

As shown, transceiver 410 may include a modem subsystem 412 and an RF unit 414. Transceiver 410 may be configured to bi-directionally communicate with other devices, such as UE 115 and/or another core network element. Modem subsystem 412 may be configured to modulate and/or encode data from memory 404, calibration module 408, and/or reporting module 409 according to a Modulation and Coding Scheme (MCS) (e.g., an LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc.). RF unit 414 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated/encoded data (regarding outbound transmissions) from modem subsystem 412 or transmissions originating from another source, such as UE 115. The RF unit 414 may also be configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated with transceiver 410, modem subsystem 412 and RF unit 414 may be separate devices that are coupled together at BS 105 to enable BS 105 to communicate with other devices.

RF unit 414 may provide modulated and/or processed data, such as data packets (or more generally, data messages containing one or more data packets and other information), to antenna 416 for transmission to one or more other devices. Antenna 416 may also receive data messages sent from other devices and provide the received data messages for processing and/or demodulation at transceiver 410. The antenna 416 may include multiple antennas of similar design or different designs in order to maintain multiple transmission links.

Fig. 5 is a block diagram of an exemplary UE 500 in accordance with an embodiment of the present disclosure. For example, UE 500 may be UE 115 as discussed above. As shown, UE 500 may include a processor 502, a memory 504, a calibration module 508, a reporting module 509, a transceiver 510 including a modem subsystem 512 and a Radio Frequency (RF) unit 514, and one or more antennas 516. These elements may communicate with each other directly or indirectly, for example, via one or more buses.

The processor 502 may include a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a controller, a Field Programmable Gate Array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 502 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Memory 504 may include cache memory (e.g., of processor 502), random Access Memory (RAM), magnetoresistive RAM (MRAM), read Only Memory (ROM), programmable Read Only Memory (PROM), erasable Programmable Read Only Memory (EPROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory, solid state memory devices, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In one embodiment, memory 504 includes a non-transitory computer-readable medium. Memory 504 may store instructions 506. The instructions 506 may include: the instructions, when executed by the processor 502, cause the processor 502 to perform the operations described herein with reference to the UE 115 in connection with embodiments of the present disclosure. The instructions 506 may also be referred to as code, which may be construed broadly to include any type of computer-readable statement, as discussed above with respect to fig. 4.

Each of the calibration module 508 and the reporting module 509 may be implemented via hardware, software, or a combination thereof. For example, each of the calibration module 508 and the reporting module 509 may be implemented as a processor, circuitry, and/or instructions 506 stored in the memory 504 and executed by the processor 502.

Each of the calibration module 508 and the reporting module 509 may be used in various aspects of the present disclosure. For example, the calibration module 508 may be configured to receive the first communication signal from a BS (e.g., BS 105). The reporting module 509 may be configured to send a request to the BS to change at least one of an antenna array size at the base station, a transmit power level at the base station and/or a beam codebook based on the first communication signal. The calibration module 508 may be configured to receive a second communication signal from the base station in response to the request.

As shown, transceiver 510 may include a modem subsystem 512 and an RF unit 514. The transceiver 510 may be configured to bi-directionally communicate with other devices, such as the BS 105. Modem subsystem 512 may be configured to modulate and/or encode data from memory 504, calibration module 508, and/or reporting module 509 according to an MCS (e.g., a Low Density Parity Check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc.). The RF unit 514 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated/encoded data (regarding outbound transmissions) from the modem subsystem 512 or transmissions originating from another source, such as another UE or BS 105. The RF unit 514 may also be configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated with transceiver 510, modem subsystem 512 and RF unit 514 may be separate devices that are coupled together at UE 115 to enable UE 115 to communicate with other devices.

The RF unit 514 may provide modulated and/or processed data, such as data packets (or more generally, data messages containing one or more data packets and other information), to the antenna 516 for transmission to one or more other devices. Antenna 516 may also receive data messages transmitted from other devices. Antenna 516 may provide received data messages for processing and/or demodulation at transceiver 510. Antenna 516 may include multiple antennas of similar design or different designs to maintain multiple transmission links. The RF unit 514 may configure the antenna 516.

Fig. 6 illustrates a signaling diagram of a method 600 for mitigating calibration errors, according to some embodiments of the disclosure. The steps of method 600 may be performed by a computing device (e.g., a processor, processing circuitry, and/or other suitable components) of a wireless communication device, such as BSs 105 and 400 and UEs 115 and 500. The method 600 may be better understood with reference to fig. 2 and 3. As shown, method 600 includes a plurality of enumerated steps, but embodiments of method 600 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. To simplify the discussion, method 600 shows one BS and one independent UE, but it should be appreciated that embodiments of the present disclosure may be extended to more UEs and/or BSs.

At step 602, BS605 transmits a first communication signal to UE 615 using a first number of multiple antenna elements and a first transmit power level. In an example, BS605 includes an antenna array that includes a plurality of antenna elements. In this example, BS605 determines a first number of the plurality of antenna elements and/or a first transmit power level based on at least one of: the size of the antenna array, the coverage area of the antenna array, the codebook size, the delay, the phase calibration error, the amplitude calibration error, or the fraction (fraction) of the failed antenna element. In another example, the transmission point (e.g., transmission point 302 in fig. 3) includes an antenna array (which includes a plurality of antenna elements) and is remote from the BS. In this example, the BS transmits the first communication signal to the UE via a transmission point.

The UE 615 receives the first communication signal from the BS 605. At step 604, the UE 615 sends feedback based on the received first communication signal, the feedback including an indication of modifying the first number and the first transmit power level for subsequent signal transmissions. In an example, the feedback includes a request to change at least one of an antenna array size at the BS605 or a transmit power level at the BS605 based on the first communication signal. In an example, the feedback includes a measurement report including at least one of RSRP, RSRQ, RSSI, SINR or SNR corresponding to a best beam pair from one or more UEs.

BS 205 may compare the measurement report to a threshold. In an example, the measurement report includes RSRP, RSRQ, RSSI, SINR or SNR metrics corresponding to the best beam pair from the UE. If some portion of the UE's power level report meets a threshold (e.g., is below or above the threshold), BS 205 may modify the number of multiple antenna elements and/or transmit power level for future signal transmissions. The BS605 may determine a second number of the plurality of antenna elements and/or a second transmit power level based on a comparison between the measurement report and the threshold.

At step 606, BS605 transmits a second communication signal to UE 615 based on the feedback, the second communication signal using a second number of the plurality of antenna elements and a second transmit power level. BS605 may use a combination of feedback, phase calibration error information, and/or amplitude calibration error information from one or more UEs in its decision to modify the number of antenna elements and transmit power level for future communication signal transmissions.

BS605 may determine a second number of the plurality of antenna elements and a second transmit power level based on the feedback. In an example, BS605 decreases the array size and increases the transmit power level such that the first number of the plurality of antenna elements is less than the second number of the plurality of antenna elements and the first transmit power level is greater than the second transmit power level. In another example, BS605 increases the array size and decreases the transmit power level such that the first number of the plurality of antenna elements is greater than the second number of the plurality of antenna elements and the first transmit power level is less than the second transmit power level. In addition, BS605 may transmit the second communication signal by applying a codebook including beamforming weights. BS605 may adjust beamforming weights in the codebook based on feedback (e.g., measurement reports).

Fig. 7 shows a flow chart of a communication method 700 according to an embodiment of the disclosure. The steps of method 700 may be performed by a computing device (e.g., processor, processing circuitry, and/or other suitable components) of a wireless communication device, such as BSs 105 and 400. Method 700 may employ similar mechanisms as in methods 200 and 300 described with respect to fig. 2 and 3, respectively. As shown, method 700 includes a plurality of enumerated steps, but embodiments of method 700 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

At step 710, the method 700 includes: the first communication signal is transmitted by the base station via an antenna array comprising a plurality of antenna elements using a first number of the plurality of antenna elements and a first transmit power level. In an example, the BS includes an antenna array including a plurality of antenna elements. In this example, the BS determines the first number of the plurality of antenna elements and/or the first transmit power level based on at least one of: the size of the antenna array, the coverage area of the antenna array, the codebook size, the delay, the phase calibration error, the amplitude calibration error, or the fraction of the failed antenna element. In another example, the transmission point (e.g., transmission point 302 in fig. 3) includes an antenna array (which includes a plurality of antenna elements) and is remote from the BS. In this example, the BS transmits the first communication signal to the UE via a transmission point.

At step 720, method 700 includes: a measurement report based on the first communication signal is received by the base station from at least one user equipment. In an example, the measurement report includes at least one of RSRP, RSRQ, RSSI, SINR or SNR metrics corresponding to the best beam pair from the UE. The BS may receive a plurality of measurement reports from a plurality of UEs.

At step 730, the method 700 includes: transmitting, by the base station, a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the one or more measurement reports, wherein at least one of: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level. The BS may determine a second number of the plurality of antenna elements and/or a second transmit power level based on a comparison between the measurement report and the threshold. In an example, the BS determines to modify the number of the plurality of antenna elements for transmitting the second communication signal from the first number to the second number and determines to modify the transmit power level for transmitting the second communication signal from the first transmit power level to the second transmit power level.

The BS may compare data included in the one or more measurement reports to a threshold. In an example, the measurement report includes at least one of RSRP, RSRQ, RSSI, SINR or SNR metrics corresponding to the best beam pair from the UE. If some portion of the UE's power level report meets a threshold (e.g., is below or above the threshold), the BS may modify the number of multiple antenna elements and/or the transmit power level for future signal transmissions. In an example, the BS may increase the number of antenna elements and decrease the transmit power level for future communication signal transmissions. In another example, the BS may reduce the number of antenna elements and increase the transmit power level for future communication signal transmissions.

In some examples, the plurality of UEs send measurement reports to the BS. Thus, the BS receives a plurality of measurement reports. The BS may aggregate the plurality of measurement reports and determine to transmit the second communication signal using the second number of the plurality of antenna elements and the second transmit power level based on the aggregated measurement reports. The change to adjust the antenna element array size may occur at any time and may be based on feedback from one or more UEs (e.g., based on measurement reports).

Fig. 8 shows a flow chart of a communication method 800 according to an embodiment of the disclosure. The steps of method 800 may be performed by a computing device (e.g., processor, processing circuitry, and/or other suitable components) of a wireless communication device, such as UEs 115 and 500. Method 800 may employ similar mechanisms as in methods 200 and 300 described with respect to fig. 2 and 3, respectively. As shown, method 800 includes a plurality of enumerated steps, but embodiments of method 800 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

At step 810, the method 800 includes: a first communication signal is received by a user equipment from a base station. In one example, the UE receives a first communication signal from the BS via a link connecting the UE and the BS. In another example, the UE receives the first communication signal from the BS via a transmission point.

At step 820, method 800 includes: a request is sent by the user equipment to the base station based on the first communication signal for at least one of changing an antenna array size at the base station or a transmit power level at the base station. In an example, the UE sends a request to change the antenna array size at the BS based on the first communication signal. In another example, the UE sends a request for changing the transmit power level at the base station BS based on the first communication signal.

At step 830, the method 800 includes: a second communication signal is received by the user equipment from the base station in response to the request. In one example, the BS modifies the antenna array size and/or the transmit power level at the base station as requested and transmits the second communication signal using the modified antenna array size and/or the transmit power level.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software for execution by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwired or a combination of any of these items. Features that implement the functions may also be physically located at various locations including being distributed such that each portion of the functions is implemented at a different physical location. Furthermore, as used herein (including in the claims), an "or" as used in a list of items (e.g., a list of items ending with a phrase such as "at least one of" or "one or more of" indicates an inclusive list, such that a list of, for example, [ A, B or at least one of C ] means a or B or C or AB or AC or BC or ABC (i.e., a and B and C).

Embodiments of the present disclosure include a method of wireless communication, comprising: transmitting, by the base station, a first communication signal via an antenna array comprising a plurality of antenna elements using a first number of the plurality of antenna elements and a first transmit power level; receiving, by the base station, a measurement report based on the first communication signal from at least one user equipment; and transmitting, by the base station, a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report, wherein at least one of: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level.

The method further comprises the steps of: the measurement report is received by receiving at least one of RSRP, RSRQ, RSSI, SINR or SNR from at least one UE. The method further comprises the steps of: the measurement report is received by receiving a request to change at least one of the first number of the plurality of antenna elements at the base station or the first transmit power level at the base station. The method further comprises the steps of: determining, by the base station, the first number of the plurality of antenna elements based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element. The method further comprises the steps of: determining, by the base station, the first transmit power level based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element.

The method further comprises the steps of: the second number of the plurality of antenna elements is determined by the base station based on a comparison between the measurement report and a threshold. The method further comprises the steps of: the second transmit power level is determined by the base station based on a comparison between the measurement report and a threshold. In one example, the first number of the plurality of antenna elements is greater than the second number of the plurality of antenna elements, and the first transmit power level is less than the second transmit power level. In another example, the first number of the plurality of antenna elements is less than the second number of the plurality of antenna elements, and the first transmit power level is greater than the second transmit power level.

The method further comprises the steps of: the second communication signal is transmitted by applying a codebook comprising beamforming weights. The method further comprises the steps of: the beamforming weights in the codebook are adjusted by the base station based on the measurement report. The method further comprises the steps of: the first communication signal is transmitted by transmitting the first communication signal to a UE via a transmission point remote from the BS, the transmission point including the antenna array.

Embodiments of the present disclosure also include a method of wireless communication, comprising: receiving, by the user equipment, a first communication signal from the base station; transmitting, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and receiving, by the user equipment, a second communication signal from the base station in response to the request.

The method further comprises the steps of: the first communication signal is received by receiving the first communication signal from a transmission point remote from the base station. The method further comprises the steps of: a metric corresponding to a best beam pair at the user equipment is transmitted to the base station, wherein the second communication signal is responsive to the metric. The metric is at least one of RSRP, RSRQ, RSSI, SINR, SNR corresponding to the best beam pair at the UE.

Embodiments of the present disclosure also include an apparatus comprising a transceiver configured to: transmitting, by the base station, a first communication signal using a first number of the plurality of antenna elements and a first transmit power level via an antenna array comprising the plurality of antenna elements; receiving, by the base station, a measurement report based on the first communication signal from at least one user equipment; and transmitting, by the base station, a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report, wherein at least one of: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level.

The transceiver is further configured to: the measurement report is received by receiving at least one of RSRP, RSRQ, RSSI, SINR or SNR from at least one UE. The transceiver is further configured to: the measurement report is received by receiving a request to change at least one of the first number of the plurality of antenna elements at the base station or the first transmit power level at the base station.

The apparatus further includes a processor configured to: determining the first number of the plurality of antenna elements based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element. The processor is further configured to: the first transmit power level is determined based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element.

The processor is further configured to: the second number of the plurality of antenna elements is determined based on a comparison between the measurement report and a threshold. The processor is further configured to: the second transmit power level is determined based on a comparison between the measurement report and a threshold. In an example, the first number of the plurality of antenna elements is greater than the second number of the plurality of antenna elements, and the first transmit power level is less than the second transmit power level. In another example, the first number of the plurality of antenna elements is less than the second number of the plurality of antenna elements, and the first transmit power level is greater than the second transmit power level.

The transceiver is further configured to: the second communication signal is transmitted by applying a codebook comprising beamforming weights. The processor is further configured to: the beamforming weights in the codebook are adjusted based on the measurement report. The transceiver is further configured to: the first communication signal is transmitted by transmitting the first communication signal to a UE via a transmission point remote from the BS, the transmission point including the antenna array.

Embodiments of the present disclosure also include an apparatus comprising a transceiver configured to: receiving, by the user equipment, a first communication signal from the base station; transmitting, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and receiving, by the user equipment, a second communication signal from the base station in response to the request.

The transceiver is further configured to: the first communication signal is received from a transmission point remote from the base station. The transceiver is further configured to: a metric corresponding to a best beam pair at the user equipment is transmitted to the base station, wherein the second communication signal is responsive to the metric. The metric is at least one of RSRP, RSRQ, RSSI, SINR, SNR corresponding to the best beam pair at the UE.

Embodiments of the present disclosure also include a computer readable medium having program code recorded thereon, the program code comprising: transmitting a first communication signal using a first number of the plurality of antenna elements and a first transmission power level via an antenna array comprising the plurality of antenna elements; code for receiving a measurement report based on the first communication signal from at least one user equipment; and code for transmitting a second communication signal using a second number of the plurality of antenna elements and a second transmission power level based on the measurement report, wherein at least one of the following holds: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmission power level is different from the second transmission power level.

The computer readable medium further comprises: code for receiving at least one of RSRP, RSRQ, RSSI, SINR or SNR from at least one UE. The computer readable medium further comprises: code for receiving information regarding at least one of changing the first number of the plurality of antenna elements at the base station or the first transmit power level at the base station. The computer readable medium further comprises: determining, by the base station, the first number of the plurality of antenna elements based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element. The computer readable medium further comprises: determining, by the base station, the first transmit power level based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element.

The computer readable medium further comprises: the method further includes determining, by the base station, the second number of the plurality of antenna elements based on a comparison between the measurement report and a threshold. The computer readable medium further comprises: the apparatus includes means for determining, by the base station, the second transmit power level based on a comparison between the measurement report and a threshold. In an example, the first number of the plurality of antenna elements is greater than the second number of the plurality of antenna elements, and the first transmit power level is less than the second transmit power level. In another example, the first number of the plurality of antenna elements is less than the second number of the plurality of antenna elements, and the first transmit power level is greater than the second transmit power level.

The computer readable medium further comprises: and code for transmitting the second communication signal by applying a codebook including beamforming weights. The computer readable medium further comprises: code for adjusting, by the base station, the beamforming weights in the codebook based on the measurement report. The computer readable medium further comprises: the apparatus includes means for transmitting the first communication signal by transmitting the first communication signal to a UE via a transmission point remote from the BS, the transmission point including the antenna array.

Embodiments of the present disclosure also include a computer readable medium having program code recorded thereon, the program code comprising: code for receiving, by a user equipment, a first communication signal from a base station; means for transmitting, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and code for receiving, by the user equipment, a second communication signal from the base station in response to the request.

The computer readable medium further comprises: code for receiving the first communication signal from a transmission point remote from the base station. The computer readable medium further comprises: the apparatus includes means for transmitting, to the base station, a metric corresponding to a best beam pair at the user equipment, wherein the second communication signal is responsive to the metric. The metric is at least one of RSRP, RSRQ, RSSI, SINR, SNR corresponding to the best beam pair at the UE.

In an additional aspect of the disclosure, an apparatus includes: a unit (e.g., transceiver 410 or calibration module 408) for transmitting a first communication signal using a first number of the plurality of antenna elements and a first transmit power level; means (e.g., transceiver 410 or reporting module 409) for receiving measurement reports based on the first communication signals from at least one user equipment; and means (e.g., transceiver 410 or calibration module 408) for transmitting a second communication signal using a second number of the plurality of antenna elements and a second transmit power level based on the measurement report (e.g., feedback 230), wherein at least one of the following holds: the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements or the first transmit power level is different from the second transmit power level.

The apparatus further comprises: means (e.g., transceiver 410 or reporting module 409) for receiving at least one of RSRP, RSRQ, RSSI, SINR or SNR from at least one UE. The apparatus further comprises: means (e.g., transceiver 410 or reporting module 409) for receiving information regarding at least one of the first number of the plurality of antenna elements at the base station or the first transmit power level at the base station. The apparatus further comprises: means (e.g., processor 402 or calibration module 408) for determining, by the base station, the first number of the plurality of antenna elements based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element. The apparatus further comprises: means (e.g., processor 402 or calibration module 408) for determining, by the base station, the first transmit power level based on at least one of: the size of the antenna array, the coverage area of the antenna array, codebook size, delay, phase calibration error, amplitude calibration error, or fraction of a failed antenna element.

The apparatus further comprises: the processor 402 or calibration module 408 is configured to determine, by the base station, the second number of the plurality of antenna elements based on a comparison between the measurement report and a threshold. The apparatus further comprises: means (e.g., processor 402 or calibration module 408) for determining, by the base station, the second transmit power level based on a comparison between the measurement report and a threshold. In an example, the first number of the plurality of antenna elements is greater than the second number of the plurality of antenna elements, and the first transmit power level is less than the second transmit power level. In another example, the first number of the plurality of antenna elements is less than the second number of the plurality of antenna elements, and the first transmit power level is greater than the second transmit power level.

The apparatus further comprises: means (e.g., transceiver 410 or calibration module 408) for transmitting the second communication signal by applying a codebook including beamforming weights. The apparatus further comprises: means (e.g., processor 402 or calibration module 408) for adjusting the beamforming weights in the codebook by the base station based on the measurement report. The apparatus further comprises: means (e.g., transceiver 410 or calibration module 408) for transmitting the first communication signal by transmitting the first communication signal to a UE via a transmission point remote from the BS, the transmission point comprising the antenna array.

Embodiments of the present disclosure also include an apparatus comprising: a unit (e.g., transceiver 510 or calibration module 508) for receiving a first communication signal from a base station; means (e.g., transceiver 510 or reporting module 509) for sending, by the user equipment, a request to the base station based on the first communication signal to change at least one of an antenna array size at the base station or a transmit power level at the base station; and means (e.g., transceiver 510 or calibration module 508) for receiving a second communication signal from the base station in response to the request.

The apparatus further comprises: means (e.g., transceiver 510 or calibration module 508) for receiving the first communication signal from a transmission point remote from the base station. The apparatus further comprises: means (e.g., transceiver 510 or reporting module 509) for transmitting to the base station a metric corresponding to the best beam pair at the user equipment, wherein the second communication signal is responsive to the metric. The metric is at least one of RSRP, RSRQ, RSSI, SINR, SNR corresponding to the best beam pair at the UE.

As will be understood by those of ordinary skill in the art, many modifications, substitutions, and changes may be made in the materials, apparatuses, configurations, and methods of use of the apparatus of the present disclosure, depending on the particular application at hand, without departing from the spirit and scope of the disclosure. In view of the foregoing, the scope of the present disclosure should not be limited to the specific embodiments shown and described herein, as they are merely exemplary, but rather should be fully commensurate with the claims appended hereto and their functional equivalents.

Claims (44)

1. A method of wireless communication, comprising:

transmitting, by the first wireless communication device, a first communication signal using a beamforming codebook;

receiving, by the first wireless communication device, an indication from a second wireless communication device to modify the beamforming codebook based on the first communication signal;

performing, by the first wireless communication device, the modification of the beamforming codebook in response to the indication; and

a second communication signal is transmitted by the first wireless communication device to the second wireless communication device using the modified beamforming codebook.

2. The method of claim 1, wherein the performing the modification comprises increasing a codebook size of the beamforming codebook.

3. The method of claim 1, wherein the performing the modification comprises reducing a codebook size of the beamforming codebook.

4. The method of claim 1, wherein the first wireless communication device comprises an antenna array or at least one antenna panel, wherein the transmitting the first communication signal comprises transmitting the first communication signal via the antenna array or the at least one antenna panel, and wherein the performing the modification comprises increasing an antenna gain of the antenna array or the at least one antenna panel.

5. The method of claim 1, wherein the receiving an indication comprises receiving a request from the second wireless communication device to perform the modification of the beam codebook.

6. The method of claim 1, wherein the receiving an indication comprises receiving one or more measurement reports indicating received signal measurements on the first communication signal.

7. The method of claim 6, wherein the receiving one or more measurement reports comprises receiving a Reference Signal Received Power (RSRP), a Reference Signal Received Quality (RSRQ), a Received Signal Strength Indicator (RSSI), a signal-to-interference plus noise ratio (SINR), or a signal-to-noise ratio (SNR).

8. The method of claim 7, wherein the performing the modification comprises reducing at least one of the RSRP, RSRQ, RSSI, SINR or SNR.

9. The method of claim 6, further comprising:

aggregating the one or more measurement reports; and

based on the aggregated measurement reports, it is determined to transmit the second communication signal using the modified beamforming codebook.

10. The method of claim 1, wherein the transmitting the second communication signal comprises applying beamforming weights from the modified beamforming codebook to the second communication signal.

11. The method of claim 10, wherein the receiving the indication comprises receiving one or more measurement reports indicating signal measurements on the first communication signal, and wherein the performing the modification comprises adjusting, by the first wireless communication device, the beamforming weights in the beamforming codebook based on the one or more measurement reports.

12. A first wireless communication device, comprising:

a transceiver; and

a processor in communication with the transceiver, wherein the first wireless communication device is configured to:

Transmitting the first communication signal using a beamforming codebook;

receiving, from a second wireless communication device, an indication to modify the beamforming codebook based on the first communication signal;

transmitting a second communication signal to the second wireless communication device using the modified beamforming codebook; and

the modification of the beamforming codebook is performed in response to the indication.

13. The first wireless communication device of claim 12, wherein the first wireless communication device comprises a Base Station (BS) or a fifth generation BS (gNB), and the second wireless communication device comprises a User Equipment (UE).

14. The first wireless communication device of claim 12, wherein the first wireless communication device comprises a Transmission Reception Point (TRP), a Customer Premise Equipment (CPE), or an Integrated Access and Backhaul (IAB) node, and the second wireless communication device comprises a UE, CPE, or IAB node.

15. The first wireless communication device of claim 12, wherein the first wireless communication device is configured to increase or decrease a codebook size of the beamforming codebook.

16. The first wireless communication device of claim 12, wherein the first wireless communication device is configured to transmit the first communication signal via an antenna array or at least one antenna panel, and wherein the first wireless communication device is configured to increase an antenna gain of the antenna array or the at least one antenna panel.

17. The first wireless communication device of claim 12, wherein the first wireless communication device is configured to receive a request from the second wireless communication device to perform the modification of the beamforming codebook, and wherein the indication comprises the request from the second wireless communication device.

18. The first wireless communication device of claim 12, wherein the first wireless communication device is configured to receive one or more measurement reports indicating received signal measurements of the first communication signal, and wherein the indication comprises the one or more measurement reports.

19. A method of wireless communication, comprising:

determining whether to adjust calibration of an antenna array or at least one antenna panel of a first wireless communication device based on results of a test stored at the first wireless communication device;

adjusting, by the first wireless communication device, at least one of a phase or amplitude calibration of the antenna array or the at least one antenna panel in response to a determination to adjust the calibration; and

a communication signal is transmitted by the first wireless communication device to a second wireless communication device based on the adjusted calibration.

20. The method of claim 19, further comprising:

transmitting, by the first wireless communication device, a second communication signal via the antenna array or the at least one antenna panel, wherein the adjusting at least one of phase or amplitude calibration includes adjusting at least one of phase or amplitude parameters associated with antenna elements of the antenna array or the at least one antenna panel.

21. The method of claim 19, further comprising:

transmitting, by the first wireless communication device, a second communication signal using a beamforming codebook, wherein the adjusting at least one of phase or amplitude calibration includes increasing a codebook size of the beamforming codebook.

22. The method of claim 19, further comprising:

transmitting, by the first wireless communication device, a second communication signal using a beamforming codebook, wherein the adjusting at least one of phase or amplitude calibration includes reducing a codebook size of the beamforming codebook.

23. The method of claim 19, further comprising:

transmitting, by the first wireless communication device, a second communication signal using a beamforming codebook;

receiving, by the first wireless communication device, one or more measurement reports indicating received signal measurements on the second communication signal; a kind of electronic device with a high-performance liquid crystal display

One or more excess sets of amplitude or phase calibration errors are determined based on the one or more measurement reports.

24. The method of claim 23, wherein the receiving one or more measurement reports comprises receiving a Reference Signal Received Power (RSRP), a Reference Signal Received Quality (RSRQ), a Received Signal Strength Indicator (RSSI), a signal-to-interference plus noise ratio (SINR), or a signal-to-noise ratio (SNR).

25. A first wireless communication device, comprising:

an antenna unit comprising an antenna array or an antenna panel;

a transceiver; and

a processor in communication with the transceiver, wherein the first wireless communication device is configured to:

determining whether to adjust calibration of the antenna array or the at least one antenna panel based on results of the test stored at the first wireless communication device;

adjusting at least one of a phase or amplitude calibration of the antenna array or the at least one antenna panel in response to a determination to adjust the calibration; and

a communication signal is sent to the second wireless communication device based on the adjusted calibration.

26. The first wireless communication device of claim 25, wherein the first wireless communication device comprises a Base Station (BS) or a fifth generation BS (gNB), and the second wireless communication device comprises a User Equipment (UE).

27. The first wireless communication device of claim 25, wherein the first wireless communication device comprises a Transmission Reception Point (TRP), a Customer Premise Equipment (CPE), or an Integrated Access and Backhaul (IAB) node, and the second wireless communication device comprises a UE, CPE, or IAB node.

28. The first wireless communication device of claim 25, wherein the first wireless communication device is configured to:

transmitting a second communication signal via the antenna array or the antenna panel; and

at least one of an amplitude or phase parameter of the antenna array or the antenna panel is adjusted.

29. The first wireless communication device of claim 25, wherein the first wireless communication device is configured to:

transmitting a second communication signal using a beamforming codebook; and

and increasing the codebook size of the beamforming codebook.

30. The first wireless communication device of claim 25, wherein the first wireless communication device is configured to:

transmitting a second communication signal using a beamforming codebook; and

the codebook size of the beamforming codebook is reduced.

31. A method of wireless communication performed by a user device, the method comprising:

Receiving, from a Base Station (BS), a first communication signal based on a first antenna array at the BS, the first antenna array comprising a first number of multiple antenna elements;

transmitting a request to the BS to modify an antenna array size at the BS based on the first communication signal; and

a second communication signal is received from the BS in response to the request, the second communication signal based on a second antenna array at the BS, and the second antenna array including a second number of multiple antenna elements.

32. The method of claim 31, wherein the first number is less than the second number.

33. The method of claim 31, wherein the first number is greater than the second number.

34. A user equipment, comprising:

a transceiver; and

a processor in communication with the transceiver, wherein the UE is configured to:

receiving, from a Base Station (BS), a first communication signal based on a first antenna array at the BS, the first antenna array comprising a first number of multiple antenna elements;

transmitting a request to the BS to modify an antenna array size at the BS based on the first communication signal; a kind of electronic device with a high-performance liquid crystal display

A second communication signal is received from the BS in response to the request, the second communication signal based on a second antenna array at the BS, and the second antenna array including a second number of multiple antenna elements.

35. The UE of claim 34, wherein the first number is less than the second number.

36. The UE of claim 34, wherein the first number is greater than the second number.

37. A method of wireless communication performed by a user device, the method comprising:

receiving a first communication signal from a Base Station (BS) based on a beamforming codebook;

transmitting an indication to the BS to modify the beamforming codebook based on the first communication signal; and

a second communication signal based on the modified beamforming codebook is received from the BS.

38. The method of claim 37, wherein the transmitting the indication comprises transmitting the indication to increase a codebook size of the beamforming codebook.

39. The method of claim 37, wherein the transmitting the indication comprises transmitting the indication to reduce a codebook size of the beamforming codebook.

40. The method of claim 37, wherein the transmitting the indication comprises transmitting one or more measurement reports indicating received signal measurements for the first communication signal.

41. A User Equipment (UE), comprising:

a transceiver; and

a processor in communication with the transceiver, wherein the UE is configured to:

receiving a first communication signal based on a beamforming codebook;

transmitting an indication to a Base Station (BS) to modify the beamforming codebook based on the first communication signal; and

a second communication signal based on the modified beamforming codebook is received from the BS.

42. The UE of claim 41, wherein the UE is further configured to transmit the indication to increase a codebook size of the beamforming codebook.

43. The UE of claim 41, wherein the UE is further configured to transmit the indication to reduce a codebook size of the beamforming codebook.

44. The UE of claim 41, wherein the UE is further configured to transmit one or more measurement reports indicating received signal measurements for the first communication signal.