Abstract: Wireless communications systems and methods related to intra-packet rate adaptation are provided. A first wireless communication device communicates, with a second wireless communication device, an intra-packet modulation coding scheme (MCS) switching configuration. The first wireless communication device receives, from the second wireless communication device, a communication signal including a first data packet based on the intra-packet MCS switching configuration. The first data packet includes at least a first portion encoded by a first MCS and a second portion encoded by a second MCS different from the first MCS.

Abstract: This disclosure provides methods, devices and systems for obtaining and providing channel feedback. In some implementations, a beamformee provides channel feedback to a beamformer that enables the beamformer to construct and independently precode two or more different sets of spatial streams for transmission to the beamformee. The independent precoding of the different sets of spatial streams ensures that the decodings of the different sets of spatial streams may be decoupled from one another at the beamformee. To provide the channel feedback, the beamformee partitions a channel estimate into two or more sub-estimates prior to performing a channel decomposition. In some implementations, the beamformee determines null-space-based projections of the sub-estimates before performing the channel decomposition.

Abstract: Wireless communications systems and methods related to intra-packet rate adaptation are provided. A first wireless communication device communicates, with a second wireless communication device, an intra-packet modulation coding scheme (MCS) switching configuration. The first wireless communication device receives, from the second wireless communication device, a communication signal including a first data packet based on the intra-packet MCS switching configuration. The first data packet includes at least a first portion encoded by a first MCS and a second portion encoded by a second MCS different from the first MCS.

Abstract: Methods and systems are disclosed herein for performing channel estimation for multi-stream packets. The method may include receiving a data packet comprising a plurality of training fields, wherein the plurality of training fields comprises a training field, wherein the training field comprises a plurality of tones, and wherein the plurality of tones comprises a first tone and a second tone. The method may include modifying the first tone based on a predetermined signal associated with the first tone. The method may include storing the first tone in a data structure associated with the first tone. The method may include modifying the data structure based on the second tone.

Abstract: Certain aspects of the present disclosure generally relate to wireless communication. In some aspects, a wireless communication device may determine an odd-exponent modulation constellation order for a group of bits; determine a parity bit location for the group of bits based at least in part on the odd-exponent modulation constellation order; and map the group of bits, with a parity bit in the parity bit location, to an odd-exponent modulation constellation of the odd-exponent modulation constellation order.

Abstract: Certain aspects of the present disclosure generally relate to wireless communication. In some aspects, a wireless communication device may determine an odd-exponent modulation constellation order for a group of bits; determine a parity bit location for the group of bits based at least in part on the odd-exponent modulation constellation order; and map the group of bits, with a parity bit in the parity bit location, to an odd-exponent modulation constellation of the odd-exponent modulation constellation order.

Abstract: Methods and systems are disclosed herein for performing channel estimation for multi-stream packets. The method may include receiving a data packet comprising a plurality of training fields, wherein the plurality of training fields comprises a training field, wherein the training field comprises a plurality of tones, and wherein the plurality of tones comprises a first tone and a second tone. The method may include modifying the first tone based on a predetermined signal associated with the first tone. The method may include storing the first tone in a data structure associated with the first tone. The method may include modifying the data structure based on the second tone.

Abstract: Methods, systems, and devices for wireless communication at a polar transmitter are described including: clipping at least a portion of an orthogonal frequency division multiplexing (OFDM) signal that exceeds a first predetermined threshold in a first sample; transferring the clipped portion of the OFDM signal to at least a second sample; and transmitting, by the polar transmitter, the OFDM signal.

Abstract: Embodiments described herein provide a method for carrier frequency offset and frequency drift cancellation based indoor position estimation. A wireless signal including a plurality of data samples is received at a receiving antenna and from a mobile device. Information relating to an antenna switching pattern for transmitting or receiving the wireless signal may then be obtained from the wireless signal. A phase difference is calculated associated with each data sample of plurality of data samples. Carrier frequency offset and frequency drift cancellation may be applied to the phase difference to obtain a compensated phase difference. A direction estimate of the mobile device may then be generated based at least in part on the compensated phase difference.

Abstract: A device for communication includes a receiver and a tuned infinite impulse response (IIR) compensation filter. The receiver is coupled to an in-phase path and a quadrature path. The tuned IIR compensation filter is coupled to one of the in-phase path or the quadrature path.

Abstract: A device includes a frequency offset (FO) estimation circuit and a frequency offset compensation circuit coupled with the frequency offset estimation circuit. The frequency offset compensation circuit is configured to (i) receive a continuous phase modulation (CPM) signal, (ii) receive, from the FO estimation circuit, an uncompensated frequency offset for a wth sampling window of the CPM signal, (iii) generate a frequency offset compensation value for a w+1st sampling window of the CPM signal based on the uncompensated frequency offset for the wth sampling window, (iv) adjust the CPM signal in the w+1st sampling window based on the frequency offset compensation value, and (v) provide the adjusted CPM signal to a filter.

Abstract: The present disclosure includes systems and techniques relating to time-varying notch filter. In one implementation, an apparatus includes a time-variant notch filter and a controller. The time-variant notch filter includes a notch depth and a notch bandwidth centered on a notch frequency. At least one of the notch depth or the notch bandwidth is based on a coefficient of the notch filter. The controller is configured to estimate a power of a packet being received and compare the estimated power of the packet to a predetermined threshold. The controller is also configured to set, conditioned on determining that the estimated power of the packet is greater than the predetermined threshold, a value of the coefficient to a first value such that the packet bypasses the time-variant notch filter.

Abstract: Systems and methods for removing DC offset from a signal are provided. A radio frequency signal is received at a receiver. The radio frequency signal is converted into a digital signal including a periodic component with a period. A carrier frequency offset is removed from the digital signal to generate a frequency-shifted digital signal. The frequency-shifted digital signal is filtered to remove a DC offset in the digital signal. The filtering includes applying a moving average filter matched to the period to remove the periodic component from the frequency-shifted digital signal. The moving average filter generates a set of average values based on the frequency-shifted digital signal. The filtering also includes taking a difference between consecutive values of the set of average values to determine the DC offset, where the DC offset is introduced at the receiver.

Abstract: The present disclosure describes methods and apparatus for generating expanded code words to support error correction in a data communication system. In some aspects data to be encoded and a first subset of bits of a first bit sequence are obtained. A first combined bit sequence is generated by combining the data and the first subset of bits. A first code word is generated by applying an error correcting code to the first combined bit sequence. The first code word is combined with the first bit sequence, resulting in first encoded data that includes both first parity information and the data. The generating, applying, and combining are repeated with a second subset of bits of a second bit sequence, resulting in second encoded data that includes both second parity information and the data, the second encoded data being based on a second code word rather than the first code word.

Abstract: Methods and apparatuses of the invention are directed to correcting errors caused by frequency offsets between clocks in a communication system, for example SFO. According to certain aspects, embodiments of the invention provide for resampling data samples corresponding to a received data symbol immediately prior to performing an FFT. According to certain additional aspects, the resampler operates only on the data samples of a cyclic data block, with a known (and minimized) sample timing error to correct.

Abstract: The present disclosure includes systems and techniques relating to time-varying notch filter. In some implementations, an apparatus includes a time-variant notch filter and a controller. The time-variant notch filter includes a notch depth and a notch bandwidth. At least one of the notch depth or the notch bandwidth is based on a coefficient of the notch filter. The controller is configured to set at least one of the notch depth to a first depth or the notch bandwidth to a first bandwidth by setting a value of the coefficient to a first value during a ramp-up of the notch filter before a packet is received. The controller is also configured to set at least one of the notch depth to a second depth or the notch bandwidth to a second bandwidth by adjusting the value of the coefficient to a second value after the packet is received.

Abstract: Systems and methods associated with origin dodging for a transmitted signal are described. One method includes receiving a transmission sequence for transmission to a receiver. The transmission sequence includes a sequence of transmit symbols and each transmit symbol corresponds to a coordinate pair positioning the transmit symbol's phase on an I-Q plane. The method includes sampling and filtering the transmission sequence to create transition samples and determining whether any transition sample is within a predetermined radius of an origin of the I-Q plane. When a transition sample is positioned within the radius, the method includes generating a dodging symbol and inserting the dodging symbol into the transmission sequence to create a modified transmission sequence. A filtered signal that includes filtered samples of the modified transmission sequence is provided.

Abstract: In a method of whitening noise in a signal received by a receiving device from a transmitting device via a multi input multi output (MIMO) communication channel, a data unit is received at the receiving device via the MIMO communication channel. A channel estimate H corresponding to the MIMO communication channel is determined based on the training signals. A noise scaling factor s is determined. The noise scaling factor s is a ratio of variance of noise at the receiving device to a variance of noise at the transmitting device. A noise whitening matrix W is determined using the channel estimate H and the noise scaling factor s. The noise whitening matrix W is applied to (i) the channel estimate H to generate an effective channel matrix Heff and (ii) to the data symbols to generate whitened data symbols.

Abstract: According to certain general aspects, the present invention provides a wireless networking scheme that adaptively modifies the transmitted signal bandwidth to avoid interference from or to other devices or systems (e.g., 802.11p) and to meet regulatory requirements (e.g., DFS). In embodiments, if a transmitter according to the invention is operating in a channel with high bandwidth, and if interference is detected or needs to be avoided on a non-primary portion of the occupied bandwidth, the transmitter adaptively reduces the portion of the bandwidth used for transmission to minimize interference. This allows the transmitter to reduce interference or meet compliance requirements without significantly compromising throughput.

Abstract: A demodulator for a Bluetooth receiver includes an oversampling module configured to oversample input symbols a first plurality of times to generate a first plurality of oversampled input symbols. A correlating module is configured to correlate a second plurality of adjacent samples of the first plurality of oversampled input symbols with corresponding symbols in a predetermined enhanced data rate (EDR) sync word. Based on the correlation, the correlating module is configured to selectively generate a sync signal indicating that EDR sync has occurred. The second plurality of adjacent samples comprises more samples than one and less than all of the first plurality of oversampled input symbols.