Abstract: This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for multistatic radar communications. In some implementations, a transmitting device may transmit, to a receiving device, a radar alert frame followed by a codeword and one or more radar pulses. The radar pulses are transmitted, using beamforming, in a number of directions. The timing information indicates a timing offset or delay between one or more codewords of the codeword sequence and the beginning of the radar pulses. The receiving device may detect one or more codewords of the codeword sequence and an echo of at least one of the radar pulses, and determine the time at which the corresponding pulse was transmitted by the transmitting device. The receiving device may compare the timing of the echo with the timing of the transmitted pulse to determine a relative distance of an object that produced the echo.

Abstract: This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for multistatic radar communications. In some implementations, a transmitting device may transmit, to a receiving device, a radar alert frame followed by a codeword and one or more radar pulses. The radar pulses are transmitted, using beamforming, in a number of directions. The timing information indicates a timing offset or delay between one or more codewords of the codeword sequence and the beginning of the radar pulses. The receiving device may detect one or more codewords of the codeword sequence and an echo of at least one of the radar pulses, and determine the time at which the corresponding pulse was transmitted by the transmitting device. The receiving device may compare the timing of the echo with the timing of the transmitted pulse to determine a relative distance of an object that produced the echo.

Abstract: This disclosure provides systems, methods, and apparatuses for wireless sensing. In some aspects, a first wireless communication device may receive a first wireless transmission including a transmit (TX) parameter information element (IE). The first wireless communication device may verify the integrity of the TX parameter IE using a message integrity code (MIC) in the first wireless transmission, discarding the first wireless transmission when the MIC does not verify the integrity of the TX parameter IE. The first wireless device may obtain one or more transmission parameters for one or more second wireless communication devices associated with the TX parameter IE. The first wireless communication device may receive a second wireless transmission from one of the second wireless communication devices and obtain one or more wireless sensing measurements associated with the second wireless transmission and the one or more transmission parameters.

Abstract: Disclosed embodiments facilitate wireless channel calibration, including ranging and direction finding, between wirelessly networked devices. In some embodiments. a method on a first station (STA) may comprise: transmitting a first NDPA frame to one or more second stations (STAs), the first NDPA frame comprising a first bit indicating that one or more subsequent frames comprise ranging or angular information; and transmitting, after a Short Interval Frame Space (SIFS) time interval, a second frame. The second frame may be one of: a Null Data Packet az (NDP_az) frame with information about a time of transmission of the NDP_az frame, or a Null Data Packet (NDP) frame, or a Beam Refinement Protocol (BRP) frame. The first NDPA frame may be unicast, multicast, or broadcast.

Abstract: This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for multistatic radar communications. In some implementations, a transmitting device may transmit, to a receiving device, a radar alert frame followed by a codeword and one or more radar pulses. The radar pulses are transmitted, using beamforming, in a number of directions. The timing information indicates a timing offset or delay between one or more codewords of the codeword sequence and the beginning of the radar pulses. The receiving device may detect one or more codewords of the codeword sequence and an echo of at least one of the radar pulses, and determine the time at which the corresponding pulse was transmitted by the transmitting device. The receiving device may compare the timing of the echo with the timing of the transmitted pulse to determine a relative distance of an object that produced the echo.

Abstract: Systems and methods are provided for estimating non-linearity of a transmitter, a receiver or both based on measurements and/or feedback. The estimation of the non-linearity may be used at the transmitter, the receiver or both to tune one or more components to reduce non-linearity. In one aspect, a method for wireless communications comprises generating at least one training signal, and outputting the at least one training signal for transmission to a wireless node. The method also comprises receiving a feedback message from the wireless node, the feedback message providing feedback of the at least one training signal received at the wireless node. The method further comprises tuning at least one component based on the feedback message.

Abstract: In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may include a processing system configured to generate a frame including a data field and a plurality of training subfields. The data field may include information indicating a different direction for transmitting each of the training subfields. The apparatus may include an interface configured to output the frame for transmission with the data field in a first direction and the training subfields in their respective directions.

Abstract: Certain aspects of the present disclosure are directed to a digital predistortion (DPD) device for use within a wireless transmitter that permits the use of a downstream digital-to-analog converter that operates at a clock rate close to the bandwidth of a digital baseband input signal. In some examples, a sampling rate of a digital baseband input signal is increased using an upsampler to obtain an increased rate digital input signal. Predistortion is applied to the increased rate digital input signal using a DPD device to obtain a predistorted digital signal. The sampling rate of the predistorted digital signal is then decreased using a downsampler to obtain a lower-rate predistorted digital signal with a sampling rate below the increased rate of the upsampler (e.g. close to the bandwidth of a digital baseband input signal). A low pass filter may be provided to filter out-of-band signal components from the predistorted digital signal.

Abstract: Disclosed embodiments facilitate wireless channel calibration, ranging, and direction finding, between networked devices. A method on a first station (STA) may comprise: broadcasting, at a first time, a first NDPA frame to a plurality of second STAs. The first NDPA frame may include a first bit indicating that one or more subsequent frames comprise ranging or angular information. After a Short Interval Frame Space (SIFS) time interval from the first time, a second frame may be broadcast. The second frame may be a Null Data Packet (NDP) frame. In response, a plurality of Compressed Beamforming (CBF) frames may be received at the first STA where each CBF frame may be received from a distinct corresponding second STA, and may include Channel Feedback Information field with information pertaining to communication channel between the first STA and the corresponding second STA. The communications may be encoded using Orthogonal Frequency Division Multiple Access.

Abstract: Disclosed is an apparatus for wireless communications. The apparatus includes a processing system configured to generate a single-channel frame, a bonded channel frame, or a MIMO channel frame. Each of the frame types includes a first portion and a second portion, said first portion being decodable by a first device operating according to a first protocol, said second portion not being decodable by the first device, wherein the first and second portions are decodable by a second device operating according to a second protocol; and an interface configured to output the frame for transmission. The second portion includes a first field including frequency-domain PRBS data for AGC, a second field including a time-domain sequence for timing of input sample window for FFT processing, and a third field including frequency-domain pilots for channel estimation. For MIMO, these fields for different transmit chains are transmitted in a time aligned manner.

Abstract: Certain aspects of the present disclosure provide techniques to reduce address collision in short sector sweeps. In some cases, the techniques involve determining whether an encoded address (e.g., a compressed address), generated using a first parameter (e.g., a seed for a hash function), identifies a first wireless node and a second wireless node as a same destination for at least one first frame including the encoded address; generating at least one second frame including an indication not to use the first parameter if the encoded address identifies the first wireless node and the second wireless node as the same destination; and outputting the at least one second frame for transmission to at least one of the first wireless node or the second wireless node.

Abstract: Apparatus for generating a header of a transmit frame, and for processing the header of a received frame. The header generating includes encoding header data bits to generate parity bits, repeating the header bits M times, repeating the parity bits N times, encoding the M repetitions of the header bits, encoding the N repetitions of the parity bits, combining the encoded M repetitions of the header bits with the N repetitions of the parity bits, and modulating the combined sequence to generate the header of the frame. The header processing includes demodulating the header to generate a sequence of bits, splitting the sequence into separate header and parity sequences, decoding the header and parity sequences to generate M header and N parity sequences, combining the M header sequences, combining the N parity sequences, and decoding the combined header sequences using the combined parity sequences to generate header data bits.

Abstract: In certain aspects of the present disclosure, an apparatus for wireless communications is provided. The apparatus comprises a plurality of block circuits, wherein each one of the plurality of block circuits is configured to receive a respective plurality of signals from a respective subset of antenna elements of an antenna array. Each one of the plurality of block circuits comprises a respective plurality of phase shifters configured to shift phases of the respective plurality of signals to obtain a respective plurality of phase-shifted signals, and a respective combiner configured to combine the respective plurality of phase-shifted signals into a respective combined signal. The apparatus also comprises a plurality of time-delay elements configured to delay the combined signals to obtain a plurality of delayed combined signals, and a combiner configured to combine the plurality of delayed combined signals into a total combined signal.

Abstract: Certain aspects of the present disclosure provide a method for wireless communications. The method comprises generating a frame comprising a first portion and a second portion. The method also comprises outputting the first portion of the frame for transmission on at least one channel, shifting a center frequency of the at least one channel, and outputting the second portion of the frame for transmission on the at least one channel after the center frequency shift.

Abstract: In certain aspects of the present disclosure, an apparatus for wireless communications is provided. The apparatus comprises a plurality of block circuits, wherein each one of the plurality of block circuits is configured to receive a respective plurality of signals from a respective subset of antenna elements of an antenna array. Each one of the plurality of block circuits comprises a respective plurality of phase shifters configured to shift phases of the respective plurality of signals to obtain a respective plurality of phase-shifted signals, and a respective combiner configured to combine the respective plurality of phase-shifted signals into a respective combined signal. The apparatus also comprises a plurality of time-delay elements configured to delay the combined signals to obtain a plurality of delayed combined signals, and a combiner configured to combine the plurality of delayed combined signals into a total combined signal.

Abstract: Certain aspects of the present disclosure are directed to digital predistortion (DPD) for use with a multi-chain wireless transmitter. In various examples described herein, the multi-chain transmitter is configured to use a single common DPD device or module for all transmit chains and to adjust the bias voltages of the power amplifiers of the separate transmit chains to operate at substantially the same backoff so the distortion to the corresponding output signals is similar. Since the distortion of the output of the different chains is similar, a single common predistortion may be applied using the single DPD device to a signal to be transmitted. Techniques are also described for calibrating the predistortion coefficients of the DPD to optimize (or otherwise set) the amount of distortion reduction to be achieved. The predistortion coefficients for the single DPD may be set or calibrated based on a particular directionality needed for beamforming.

Abstract: Certain aspects of the present disclosure are directed to a digital predistortion (DPD) device for use within a wireless transmitter that permits the use of a downstream digital-to-analog converter that operates at a clock rate close to the bandwidth of a digital baseband input signal. In some examples, a sampling rate of a digital baseband input signal is increased using an upsampler to obtain an increased rate digital input signal. Predistortion is applied to the increased rate digital input signal using a DPD device to obtain a predistorted digital signal. The sampling rate of the predistorted digital signal is then decreased using a downsampler to obtain a lower-rate predistorted digital signal with a sampling rate below the increased rate of the upsampler (e.g. close to the bandwidth of a digital baseband input signal). A low pass filter may be provided to filter out-of-band signal components from the predistorted digital signal.

Abstract: A technique is disclosed for reducing interference in a communication system including a plurality of wireless devices. A first device transmits an RTS-TRN frame including a Request to Send (RTS) portion and a first beam training sequence to determine whether a communication medium is available to communicate with a second device. If the communication medium is available, the second device transmits a CTS-TRN frame including a Clear to Send (CTS) portion and a second beam training sequence. One or more neighboring devices that receive the RTS-TRN frame and/or the CTS-TRN frame configure their respective antennas to generate one or more nulls aimed at the first and second devices when transmitting signals, as long as the first and second devices are communicating based on a duration field in the RTS-TRN frame and/or CTS-TRN frame. This reduces interference at the first and/or second devices.

Abstract: A technique is disclosed for reducing interference in a communication system including a plurality of wireless devices. A first device transmits an RTS-TRN frame including a Request to Send (RTS) portion and a first beam training sequence to determine whether a communication medium is available to communicate with a second device. If the communication medium is available, the second device transmits a CTS-TRN frame including a Clear to Send (CTS) portion and a second beam training sequence. One or more neighboring devices that receive the RTS-TRN frame and/or the CTS-TRN frame configure their respective antennas to generate one or more nulls aimed at the first and second devices when transmitting signals, as long as the first and second devices are communicating based on a duration field in the RTS-TRN frame and/or CTS-TRN frame. This reduces interference at the first and/or second devices.

Abstract: In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may include a processing system configured to generate a frame including a data field and a plurality of training subfields. The data field may include information indicating a different direction for transmitting each of the training subfields. The apparatus may include an interface configured to output the frame for transmission with the data field in a first direction and the training subfields in their respective directions.