Systems and methods of calibrating a phased array antenna

Abstract

A method including: equipping each antenna element in a mmWave antenna with 2 -bit phase shift registers; for each antenna element, cycling through predetermined phase shifts to receive signals associated with each of the predetermined phase shifts; processing RSS values of the received signals to determine a relative gain of the nth element in comparison to the 1st element; and repeating the above process for other elements, to determine a relative gain of each element with respect to the 1st element.

Description

SYSTEMS AND METHODS OF CALIBRATING A PHASED ARRAY ANTENNACROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 644,832, filed on May 9, 2024, the entire contents of which are incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under grant / contract nos. 2112471, 2007581, and 2128567 awarded by the National Science Foundation. The government has certain rights in the invention.BACKGROUND

[0003] Antenna array calibration is a step in mmWave device manufacturing. It compensates for relative gains among the elements within antenna arrays, enabling signals from each element to precisely combine in a specific direction, thereby maximizing the signal -to-noise ratio (SNR) during communications. Without calibration, the signals from different elements may interfere destructively, leading to a significant reduction in the SNR and consequently affecting the overall network performance.

[0004] Conventional calibration methods may rely on costly laboratory environments. For example, conventional calibration methods may require an anechoic chamber to prevent external signal interference, a rotor arm and rail arm to manipulate the antenna array’s orientation and distance relative to a measurement horn antenna, extensive cabling systems for connectivity, and / or a vector network analyzer (VNA). The need for specialized equipment and laboratory environments may lead to significant investment in instrumentation purchase, environment setup, equipment maintenance, and personnel training, making the calibration process a bottleneck in scaling up mmWave device production.SUMMARY

[0005] In some aspects, the techniques described herein relate to a method including: equipping each antenna element in a mmWave antenna with 2 -bit phase shift registers; for each antennaelement, cycling through predetermined phase shifts to receive signals associated with each of the predetermined phase shifts; processing RSS values of the received signals to determine a relative gain of the nth element in comparison to the 1st element; and repeating the above process for other elements, to determine a relative gain of each element with respect to the 1st element.

[0006] In some aspects, the 2 -bit phase shift registers provide for phase shift values of 0, TT / 2, TT, and 3TT / 2. In some aspects, received signals include a mix of a constant-phase signal from a 1st element in the mmWave antenna and a varying-phase signals emitted by the nth element in the mmWave antenna. In some aspects, the RSS values are processed using a Fast Fourier Transform (FFT). In some aspects, the method further includes aggregating phase values within the relative gain of each element to determine a cumulative average. In some aspects, the method further includes calibrating the mmWave antenna by adjusting the relative gain of each antenna element based on the cumulative average. In some aspects, the process is repeated for at least 300 communication instances.

[0007] In some aspects, the techniques described herein relate to a mmWave device, including: a phased array antenna having a number of antenna elements; a number of n-bit phase shift registers each coupled to an antenna element and configured to cause a phase shift to be imparted on a signal transmitted from the antenna element; and a processing circuit including a processor and memory, the memory having instructions stored thereon that, when executed by the processor, cause the processing circuit to: cause the phased array antenna to perform at least k transmission instances, wherein each transmission instance includes at least four transmissions from a pair of antenna elements of the number of antenna elements; receive, from one or more receiving devices, a number of received signal strength (RSS) measurements corresponding to the k transmission instances; identify, from the number of RSS measurements, a subset of measurements; determine, based on at least i measurements from the subset of measurements, a relative gain for each of at least m antenna elements; determine, based on the relative gain for each of the at least m antenna elements, a cumulative relative gain for the at least m antenna elements; determine, based on the cumulative relative gain, a complex gain for each of the at least m antenna elements; and update at least m of the n-bit phase shift registers to store a value based on the complex gain corresponding to that antenna element.

[0008] In some aspects, the subset of measurements include at least 300 measurements. In some aspects, determining the cumulative relative gain includes: selecting a central antenna element from the number of antenna elements as a reference element; and determining the cumulativerelative gain by calculating a cumulative relative gain of other antenna elements in relation to the reference element. In some aspects, the pair of antenna elements are adjacent to one another. In some aspects, at least one RSS measurement of the number of RSS measurements is received from a cellphone. In some aspects, the at least four transmissions include: a first transmission wherein a first antenna element of the pair of antenna elements imparts a first phase shift; a second transmission wherein the first antenna element imparts a second phase shift; a third transmission wherein the first antenna element imparts a third phase shift; a fourth transmission wherein the first antenna element imparts a fourth phase shift; and wherein a second antenna element of the pair of antenna elements imparts a fixed phase shift for the first, second, third, and fourth transmissions. In some aspects, the number of RSS measurements are taken at a number of distinct locations. In some aspects, identifying the subset of measurements includes selecting, from the number of RSS measurements, measurements that form a uniform distribution of angle of departure (AoD) occurrences as the subset. In some aspects, determining the relative gain for each of the at least m antenna elements includes computing a Fast Fourier Transform (FFT). In some aspects, m is greater than or equal to half the number of antenna elements. In some aspects, the n- bit phase shift registers are configured to impart a number of discrete phase shift values, and wherein updating the at least m of the n-bit phase shift registers includes: identifying a discrete phase shift value from the number of discrete phase shift values based on the complex gain determined for a particular antenna element; and updating the n-bit phase shift register corresponding to the particular antenna element based on the identified discrete phase shift value. In some aspects, the number of received signal strength (RSS) measurements include at least 10,000 distinct RSS measurements.

[0009] In some aspects, the techniques described herein relate to a method for calibrating a phased array antenna, including: causing the phased array antenna to perform a number of transmissions; receiving, using one or more receivers at a number of distinct locations, the number of transmissions; determining, based on the number of received transmissions, a number of received signal strength (RSS) values; determining, based on the number of RSS values, a relative gain for each of a number of antenna elements of the phased array antenna, wherein determining the relative gain includes computing a Fast Fourier Transform (FFT); determining, based on the relative gain for each of the number of antenna elements, a cumulative relative gain; determining, based on the cumulative relative gain, a complex gain for each of the number of antenna elements; and adjust one or more phase shift registers associated with the phased array antenna based on thecomplex gain for each of the number of antenna elements to improve a signal -to-noise ratio (SNR) of the phased array antenna.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other aspects and features of the present disclosure will become more apparent to those skilled in the art from the following detailed description of the example embodiments with reference to the accompanying drawings.

[0011] FIG. 1 is a block diagram of a wireless communication network including a mmWave device, according to an exemplary embodiment.

[0012] FIG. 2 is a schematic illustration of a pair of antenna elements in a phased array antenna, according to an exemplary embodiment.

[0013] FIG. 3 is a flow diagram illustrating a method of calibrating one or more antenna elements of an antenna, according to an exemplary embodiment.

[0014] FIG. 4 is an example layout of a phased array antenna.

[0015] FIG. 5 is an example AoD distribution usable for selecting calibration data.DETAILED DESCRIPTION

[0016] Referring generally to the FIGURES, described herein are systems and methods of calibrating a phased array antenna. The system and methods described herein may address one or more shortcomings of conventional systems by reducing a complexity and / or overhead (e.g., time, cost, etc.) of antenna calibration and may enable calibration in everyday communication scenarios (e.g., such as in homes, offices, or urban areas, etc.). Rather than rely on specialized calibration equipment, systems and methods of the present disclosure may enable calibration using everyday devices such as cellphones that may not necessarily have been previously calibrated themselves.

[0017] In brief, systems and methods of the present disclosure facilitate antenna calibration without prior knowledge of the angle of departure (AoD) of a transmission beam. An antenna, such as a phased array antenna, may use complex weights to adjust AoD. The AoD is determined based on a combination of the complex weights (which are controllable) and relative gains (which are inherent to each antenna element — e.g., based on manufacturing variances, environmental influences, component aging, etc.). Systems and methods of the present disclosure may determinethe relative gains using a number of received signal strength (RSS) measurements to zero out the influence of AoD and known complex weights, thereby enabling calibration of the antenna (e.g., by adjusting the phase shift — i.e., complex weight — applied to each antenna element to compensate for the relative gains) with little to no human intervention.

[0018] This technology can be broadly applied in areas requiring mmWave communication. As non-limiting examples, systems and methods of the present disclosure can be applied to 5G network infrastructures, Wireless Local Area Networks (WLAN), Vehicle-to-Everything (V2X) communications, and / or future 6G communication technologies.

[0019] Turning now to FIG. 1, wireless communication network 100 is shown, according to an exemplary embodiment. Wireless communication network 100 may enable transmission / receipt of data between two or more systems / devices. As an example, wireless communication network 100 may be a fifth-generation (5G) network including base stations (BSs), such as a 5G base station (5G Node B (gNB)) or an enhanced Node B (eNB) for long term evolution (LTE) communication. Wireless communication network 100 may include, but is not limited to, radio access networks (RANs), a core network, a public switched telephone network (PSTN), the Internet, and other networks (e.g., private and / or public data-packet networks, corporate intranets, etc.).

[0020] Wireless communication network 100 is shown to include one or more receiving device(s) 110 and one or more mmWave device(s) 120. mmWave device(s) 120 may be, include, or form part of a BS. For example, mmWave device(s) 120 may provide wireless communication coverage to receiving device(s) 110 such that each receiving device(s) 110 can be communicatively linked to one or more other receiving device(s) 110. Receiving device(s) 110 are configured to communicate in wireless communication network 100 by transmitting and receiving wireless signals. Receiving device(s) 110 may be or include one or more devices such as mobile phone(s) 112, vehicle(s) 114, user equipment (UE) 116, and / or loT device(s) 118. Additionally or alternatively, receiving device(s) 110 may be or include any suitable device such as a wireless transmit / receive unit, a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a computer, a touchpad, a wireless sensor, wearable devices, and / or consumer electronics device.

[0021] In various embodiments, receiving device(s) 110 facilitate calibrating mmWave device(s) 120. For example, receiving device(s) 110 may include one or more antennae and may be capableof establishing a connection with mmWave device(s) 120 (e.g., directly and / or indirectly such as through another network / connection) to transmit information to mmWave device(s) 120 (e.g., a measurement such as a reference signal received power (RSRP), a reference signal received quality (RSRQ), a received signal strength (RSS) measurement, and / or the like). In various embodiments, receiving device(s) 110 may include a processor and / or memory. The memory may have instructions stored thereon that, when executed by the processor, cause receiving device(s) 110 to perform one or more operations as described herein. For example, the instructions may cause receiving device(s) 110 to perform one or more steps of method 300.

[0022] In various embodiments, mmWave device(s) 120 are capable of beamforming (i.e., the use of multiple antennas to control the direction of a wavefront by appropriately weighting the magnitude and phase of individual antenna signals, etc.).

[0023] mmWave device(s) 120 may include one or more antenna(s) 130, phase shift register(s) 140, and / or processing circuit(s) 150. Additionally or alternatively, mmWave device(s) 120 may include other components such any suitable structure for generating signals for wireless transmission (e.g., a transmitter, etc.) and / or any suitable structure for receiving and / or processing signals (e.g., a transceiver, digital signal processor, control electronics, etc.).

[0024] Antenna(s) 130 may include one or more antenna element(s) 132. One or more antenna elements of antenna element(s) 132 may be associated with a relative gain. The relative gain may be inherent to the antenna element. The relative gain include a relative amplitude deviation and / or a relative phase deviation.

[0025] Phase shift register(s) 140 may be configured to impart a phase shift on a signal transmitted from antenna element(s) 132. In various embodiments, each antenna element of antenna element(s) 132 is associated with a phase shift register of phase shift register(s) 140. The phase shift imparted by phase shift register(s) 140 may correspond to a value stored in an / / -bit register. For example, a 2 -bit register may store values corresponding to a phase shift of 0, pi / 2, pi, and / or 3pi / 2. A signal transmitted from each antenna elemtent of antenna element(s) 132 may be the product of a complex weight (e.g., as determined based on the phase shift applied by each phase shift register(s) 140, etc.) and a relative gain. The complex weight may include an amplitude and / or a phase shift. The phase shift may be controlled by phase shift register(s) 140. The amplitude may be controlled by a signal generator such as a transmitter. Phase shift register(s) 140may be configured to individually control the phase shift applied to each of antenna element(s) 132.

[0026] Processing circuit(s) 150 may include one or more processor(s) 152 and / or one or more memory(s) 154. Processor(s) 152 may implement various processing operations of mmWave device(s) 120. For example, processor(s) 152 can perform signal coding, data processing, power control, input / output processing, antenna calibration, or any other functionality enabling mmWave device(s) 120 to operate in a wireless communication system. Processor(s) 152 can include any suitable processing or computing device configured to perform one or more operations. For example, processor(s) 152 can include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application-specific integrated circuit.

[0027] Memory(s) 154 can include any suitable volatile and / or non-volatile storage and retrieval device, and any suitable type of memory can be used, such as random-access memory (RAM), read-only memory (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like. In various embodiments, memory(s) 154 having instructions stored thereon that, when executed by processor(s) 152, cause processing circuit(s) 150 to perform one or more operations as described herein. For example, the instructions may cause processing circuit(s) 150 to perform one or more steps of method 300.

[0028] Turning now to FIG. 2, a schematic representation of a pair of antenna elements is shown, according to an exemplary embodiment. As shown, a transmitter TX sends a signal x towards a receiver RX (not shown). The received signal y is represented as:where the operation ° denotes the Hadamard product, implying element-wise multiplication between vectors. Vector v is the vector of complex weights at the TX, representing the phase shifts applied to the NTX antenna elements to steer the beam and the amplitude information of each antenna element. Vector v can be represented as:

[0029] Vector q represents the inherent gains within the antenna elements, embodying amplitude and phase deviations. The deviations are intrinsic to the system (e.g., based on manufacturing variances, environmental influences, component aging, etc.). Vector q can be represented as:

[0030] Vectors w, p, and n are vectors of complex weights, inherent gains, and noise at the RX, respectively. Matrix H describes the channel’s propagation effects:where K denotes the number of paths, hk is the complex gain of the channel along the Zr-th path. For the A th path, the AoD at the TX is denoted by 0k, and the angle of arrival (AoA) at the RX is denoted by ipk. gt(0k) and gr(ipk) represent the array responses at the TX and RX, respectively. Laboratory calibration may require (i) a fixed path (e.g., where a probe is positioned to maintain a constant relative position and angle with the tested element), (ii) a coherent signal (e.g., where a VNA may be used to synchronize the probe and the tested element), and / or (iii) a known AoD (e.g., where a probe is positioned to directly face the center of the tested element). Systems and methods of the present disclosure may facilitate antenna calibration using (i) variable paths (e.g., via multiple communication instances that may originate from different devices each having unique paths relative to the mmWave device or access point, etc.), (ii) incoherent signals, and / or (iii) unknown AoDs.

[0031] Turning now to FIG. 3, method 300 for calibrating a phased array antenna is shown, according to an exemplary embodiment. In various embodiments, one or more components of wireless communication network 100 perform method 300. For example, receiving device(s) 110 and / or mmWave device(s) 120 may perform one or more steps of method 300. Speaking generally, method 300 includes measuring relative gains among antenna elements during beam training for each communication instance. The relative gains include the influence of AoD. The phase values from the measured relative gains may be aggregated to mitigate the impact of AoD, thereby isolating the relative gain from the impact of AoD. In various embodiments, aggregating phase values from relative gains causes the cumulative mean to tend toward zero (e.g., over a symmetric range) based on a fundamental property of sine functions, thereby mitigating the impact of AoD.

[0032] At step 310, method 300 may include performing a number of transmissions. For example, a mmWave device may transmit a number of signals via an antenna such a phased array antenna. In various embodiments, step 310 includes using one antenna element as a reference point which continuously transmits signals at a fixed phase (e.g., zero phase, etc.). Another antenna element(e.g., an antenna element to be calibrated) may transmit signals at varying phases. For example, an antenna element may be equipped with a 2 -bit phase shift register and the antenna element may cycle through four distinct phase shifts (e.g., zero, pi / 2, pi, and 3pi / 2, etc.). In various embodiments, step 310 includes a number of transmission instances, each including a number of discrete transmissions. For example, a transmission instance may include four discrete transmissions from a pair of antenna elements in which a first antenna element of the pair of antenna elements uses a fixed phase for all four transmissions and a second antenna element of the pair of antenna elements cycles through four discrete phases. In some embodiments, for each transmission, only two elements are activated (e.g., a reference antenna element and an antenna element to be calibrated). In some embodiments, a transmission instance includes transmissions from a single antenna element to be calibrated. Additionally or alternatively, a transmission instance may include transmissions from a number of antenna elements to be calibrated (e.g., where each antenna element performs transmissions in sequence, etc.).

[0033] At step 320, method 300 may include receiving, using one or more receivers, the number of transmissions. For example, mobile phone(s) 112, vehicle(s) 114, UE 116, and / or loT device(s) 118 may receive one or more of the number of transmissions. In various embodiments, the number of transmissions are received in one or more discrete locations. For example, the number of transmissions may include a number of transmission instances and the transmissions corresponding to each transmission instance may be received by a single device in approximately the same location (e.g., within 3 feet of the location, etc.) while transmissions corresponding to other transmission instances are received by other devices in other locations. In various embodiments, the received transmissions (i.e., received signals) include a mix of a constant-phase signal from a reference antenna element and a varying-phase signal from the antenna element to be calibrated.

[0034] At step 330, method 300 may include determining, based on the number of transmissions, a number of received signal strength (RSS) values. For example, each received signal may have a corresponding RSS value (e.g., as measured by hardware / software of the receiving device). In some embodiments, step 330 includes transmitting the RSS values to the transmitting device to facilitate calibration of the transmitting device. For example, one or more receivers may transmit RSS values to a mmWave device.

[0035] At step 340, method 300 may include determining, based on the number of RSS values, a relative gain for each of a number of antenna elements. For example, a computing device (e.g., aprocessing circuit, etc.) of a mmWave device may process the RSS values by computing a relative gain for each antenna element to be calibrated based on the RSS values of a reference antenna element and the antenna element to be calibrated. In some embodiments, the reference antenna element is fixed for calibration of the entire antenna array. Additionally or alternatively, the reference antenna may be dynamic throughout calibration of the antenna array (e.g., an adjacent antenna element to the antenna element to be calibrated may be used as a reference antenna element, etc.). In various embodiments, the relative gain is determined according to:where ynis an RSS value for an antenna element to be calibrated and yi is an RSS value for a reference antenna element. In various embodiments, one or more steps of method 300 are repeated. For example, steps 310-330 may be repeated for each antenna element to be calibrated (e.g., some or all of the antenna elements in a phased array antenna, etc.). As another example, the relative gain may be determined according to:where adjacent antenna elements serve as references for one another. For example, with reference to the exemplary phased array antenna show in FIG. 4, in the rightmost column, element #3 serves as the reference for element #4, element #4 for element #12, and element #12 for element #10 and in a similar manner, elements in other columns may also sequentially serve as references for each other. As another example, along the X-axis, element #3 may serve as the reference for element #1, and element #1 as the reference for element #7, and so on.

[0036] In some embodiments, method 300 includes identifying a subset of measurements corresponding to uniform AoD distribution of occurrence counts. For example, after determining relative gains for each communication instance, method 300 may include computing the vector q ° v, and computing the product of q ° v with a codebook of complex weight vectors to obtain peak correlation values. In various embodiments, the AoD angles corresponding to each peak correlation value are used to derive the AoD distribution across all communication instances, as illustrated in the exemplary distribution shown in FIG. 5. In various embodiments, identifying thesubset of measurements includes identifying the occurrence count of the AoD angle with the minimum count across all directions. For example, by selecting nine instances for each AoD angle (e.g., corresponding to the minimum count of nine), a uniform AoD distribution may be generated.

[0037] Referring again to FIG.3, at step 350, method 300 may include determining, based on the relative gain for each of the number of antenna elements, a cumulative relative gain. For example, a processing circuit of a mmWave device may aggregate the phase values within the relative gains (e.g., pn- Pi+(n-l)*pi*sin(9k)) and determine their cumulative average. In various embodiments, as the number of accumulated instances increases, the influence of the AoD within the sine function trends towards zero, thereby enabling recovery of complex gains.

[0038] At step 360, method 300 may include determining, based on the cumulative relative gain, a complex gain for each of the number of antenna elements. For example, a processing circuit of a mmWave device may determine a complex gain for each antenna element according to:where [-0, 0] represents a beamforming angle range (e.g., centered at zero), M represents the number of communication instances, and 0™represents the A111AoD within the mthcommunication instance.

[0039] In some embodiments, one or more steps of method 300 (e.g., step 340, step 350 and / or step 360) are performed using a reference element. For example, with reference to the exemplary phased array antenna show in FIG. 4, a central antenna element such as element 26 may be selected as the reference element. As another example, after measuring the relative gains between adjacent elements (e.g., such as between element #3 and element #4, element #4 and element #12, and element #12 and element #10), the measurements may be combined to determine the cumulative gain of elements #4, #12, and #10 with respect to the reference element #3. In various embodiments, selecting a central antenna element as a reference element reduces cumulative estimation errors of relative gains.

[0040] At step 370, method 300 may include adjusting one or more phase shift registers associated with the antenna based on the complex gain for each of the number of antenna elements. For example, step 370 may include adjusting each phase shift register corresponding to each antenna element to be calibrated. In various embodiments, step 370 improves a signal -to-noise ratio (SNR) of the antenna. In some embodiments, method 300 includes performing subsequent signal transmissions using the updated phase shift registers. For example, once calibrated via method 300, a mm Wave device may perform beamforming.

[0041] As utilized herein with respect to numerical ranges, the terms “approximately,” “about,” “substantially,” and similar terms generally mean+ / -10% of the disclosed values, unless specified otherwise. As utilized herein with respect to structural features (e.g., to describe shape, size, orientation, direction, relative position, etc.), the terms “approximately,” “about,” “substantially,” and similar terms are meant to cover minor variations in structure that may result from, for example, the manufacturing or assembly process and are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.

[0042] It should be noted that the term “exemplary” and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

[0043] The term “coupled” and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resultingin a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic.

[0044] References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the figures. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

[0045] The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general -purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0046] Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above. Such variation may depend, for example, on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations of the described methods could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.

[0047] The term “client or “server” include all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, or combinations, of the foregoing. The apparatus may include special purpose logic circuitry, e.g., a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). The apparatus may also include, in addition to hardware, code that creates an execution environment for the computer program in question (e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them). The apparatus and execution environment may realize various different computing model infrastructures, such as web services, distributed computing and grid computing infrastructures.

[0048] The systems and methods of the present disclosure may be completed by any computer program. A computer program (also known as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program may be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0049] The processes and logic flows described in this specification may be performed by one or more programmable processors executing one or more computer programs to perform actions by operating on input data and generating output. The processes and logic flows may also be performed by, and apparatus may also be implemented as, special purpose logic circuitry (e.g., an FPGA or an ASIC).

[0050] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing actions in accordance with instructions and one or more memory devices forstoring instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data (e.g., magnetic, magneto-optical disks, or optical disks). However, a computer need not have such devices. Moreover, a computer may be embedded in another device (e.g., a vehicle, a Global Positioning System (GPS) receiver, etc.). Devices suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices (e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD ROM and DVD-ROM disks). The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0051] To provide for interaction with a user, implementations of the subject matter described in this specification may be implemented on a computer having a display device (e.g., a CRT (cathode ray tube), LCD (liquid crystal display), OLED (organic light emitting diode), TFT (thin- film transistor), or other flexible configuration, or any other monitor for displaying information to the user. Other kinds of devices may be used to provide for interaction with a user as well; for example, feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback).

[0052] Implementations of the subject matter described in this disclosure may be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a client computer) having a graphical user interface or a web browser through which a user may interact with an implementation of the subject matter described in this disclosure, or any combination of one or more such back end, middleware, or front end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a LAN and a WAN, an inter-network (e.g., the Internet), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks).

Claims

WHAT IS CLAIMED IS:

1. A method comprising: equipping each antenna element in a mmWave antenna with 2-bit phase shift registers; for each antenna element, cycling through predetermined phase shifts to receive signals associated with each of the predetermined phase shifts; processing RSS values of the received signals to determine a relative gain of the nth element in comparison to the 1st element; and repeating the above process for other elements, to determine a relative gain of each element with respect to the 1st element.

2. The method of claim 1, wherein the 2-bit phase shift registers provide for phase shift values of 0, TT / 2, TT, and 3TT / 2.

3. The method of claim 1, wherein received signals comprise a mix of a constant-phase signal from a 1st element in the mmWave antenna and a varying-phase signals emitted by the nth element in the mmWave antenna.

4. The method of claim 1, wherein the RSS values are processed using a Fast Fourier Transform (FFT).

5. The method of claim 1, further comprising aggregating phase values within the relative gain of each element to determine a cumulative average.

6. The method of claim 5, further comprising calibrating the mmWave antenna by adjusting the relative gain of each antenna element based on the cumulative average.

7. The method of claim 6, wherein the process is repeated for at least 300 communication instances.

8. A mmWave device, comprising: a phased array antenna having a plurality of antenna elements; a plurality of / / -bit phase shift registers each coupled to an antenna element and configured to cause a phase shift to be imparted on a signal transmitted from the antenna element; and a processing circuit comprising a processor and memory, the memory having instructions stored thereon that, when executed by the processor, cause the processing circuit to:cause the phased array antenna to perform at least ^transmission instances, wherein each transmission instance includes at least four transmissions from a pair of antenna elements of the plurality of antenna elements; receive, from one or more receiving devices, a plurality of received signal strength (RSS) measurements corresponding to the k transmission instances; identify, from the plurality of RSS measurements, a subset of measurements; determine, based on at least i measurements from the subset of measurements, a relative gain for each of at least m antenna elements; determine, based on the relative gain for each of the at least m antenna elements, a cumulative relative gain for the at least m antenna elements; determine, based on the cumulative relative gain, a complex gain for each of the at least m antenna elements; and update at least m of the / / -bit phase shift registers to store a value based on the complex gain corresponding to that antenna element.

9. The mmWave device of claim 8, wherein the subset of measurements comprise at least 300 measurements.

10. The mmWave device of claim 8, wherein determining the cumulative relative gain comprises: selecting a central antenna element from the plurality of antenna elements as a reference element; and determining the cumulative relative gain by calculating a cumulative relative gain of other antenna elements in relation to the reference element.

11. The mmWave device of claim 8, wherein the pair of antenna elements are adjacent to one another.

12. The mmWave device of claim 8, wherein at least one RSS measurement of the plurality of RSS measurements is received from a cellphone.

13. The mmWave device of claim 8, wherein the at least four transmissions comprise: a first transmission wherein a first antenna element of the pair of antenna elements imparts a first phase shift; a second transmission wherein the first antenna element imparts a second phase shift; a third transmission wherein the first antenna element imparts a third phase shift;a fourth transmission wherein the first antenna element imparts a fourth phase shift; and wherein a second antenna element of the pair of antenna elements imparts a fixed phase shift for the first, second, third, and fourth transmissions.

14. The mmWave device of claim 8, wherein the plurality of RSS measurements are taken at a plurality of distinct locations.

15. The mmWave device of claim 8, wherein identifying the subset of measurements comprises selecting, from the plurality of RSS measurements, measurements that form a uniform distribution of angle of departure (AoD) occurrences as the subset.

16. The mmWave device of claim 8, wherein determining the relative gain for each of the at least m antenna elements comprises computing a Fast Fourier Transform (FFT).

17. The mmWave device of claim 8, wherein m is greater than or equal to half the plurality of antenna elements.

18. The mmWave device of claim 8, wherein the / / -bit phase shift registers are configured to impart a number of discrete phase shift values, and wherein updating the at least m of the / / -bit phase shift registers comprises: identifying a discrete phase shift value from the number of discrete phase shift values based on the complex gain determined for a particular antenna element; and updating the / / -bit phase shift register corresponding to the particular antenna element based on the identified discrete phase shift value.

19. The mmWave device of claim 18, the plurality of received signal strength (RSS) measurements comprise at least 10,000 distinct RSS measurements.

20. A method for calibrating a phased array antenna, comprising: causing the phased array antenna to perform a plurality of transmissions; receiving, using one or more receivers at a plurality of distinct locations, the plurality of transmissions; determining, based on the plurality of received transmissions, a plurality of received signal strength (RSS) values; determining, based on the plurality of RSS values, a relative gain for each of a plurality of antenna elements of the phased array antenna, wherein determining the relative gain comprises computing a Fast Fourier Transform (FFT);determining, based on the relative gain for each of the plurality of antenna elements, a cumulative relative gain; determining, based on the cumulative relative gain, a complex gain for each of the plurality of antenna elements; and adjust one or more phase shift registers associated with the phased array antenna based on the complex gain for each of the plurality of antenna elements to improve a signal -to-noise ratio (SNR) of the phased array antenna.

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