Abstract: Methods, systems, and devices for wireless communication are described. In some systems (e.g., Wi-Fi systems), a transmitting device such as an access point (AP) or mobile station (STA), may identify a number of spatial streams for a data transmission that is less than a number of transmit antennas, and may transmit a packet over a channel. In a first implementation, the packet may be formatted in a multi-user frame format, with a number of long training field (LTF) symbols equal to the number of transmit antennas. In a second implementation, the packet may be a null data packet (NDP), and the device may transmit a separate data packet. In a third implementation, the packet may be formatted in single-user frame format with a modified LTF. A receiving device may receive the packet, and may perform channel estimation and power amplifier (PA) distortion cancellation based on the received packet.

Abstract: Methods, systems, and devices for wireless communication are described. In some systems (e.g., Wi-Fi systems), a transmitting device such as an access point (AP) or mobile station (STA), may identify a number of spatial streams for a data transmission that is less than a number of transmit antennas, and may transmit a packet over a channel. In a first implementation, the packet may be formatted in a multi-user frame format, with a number of long training field (LTF) symbols equal to the number of transmit antennas. In a second implementation, the packet may be a null data packet (NDP), and the device may transmit a separate data packet. In a third implementation, the packet may be formatted in single-user frame format with a modified LTF. A receiving device may receive the packet, and may perform channel estimation and power amplifier (PA) distortion cancellation based on the received packet.

Abstract: Methods, systems, and devices for wireless communication are described. In some systems (e.g., Wi-Fi systems), a transmitting device such as an access point (AP) or mobile station (STA), may identify a number of spatial streams for a data transmission that is less than a number of transmit antennas, and may transmit a packet over a channel. In a first implementation, the packet may be formatted in a multi-user frame format, with a number of long training field (LTF) symbols equal to the number of transmit antennas. In a second implementation, the packet may be a null data packet (NDP), and the device may transmit a separate data packet. In a third implementation, the packet may be formatted in single-user frame format with a modified LTF. A receiving device may receive the packet, and may perform channel estimation and power amplifier (PA) distortion cancellation based on the received packet.

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: Methods, systems, and devices for wireless communication are described. In some systems (e.g., Wi-Fi systems), a transmitting device such as an access point (AP) or mobile station (STA), may identify a number of spatial streams for a data transmission that is less than a number of transmit antennas, and may transmit a packet over a channel. In a first implementation, the packet may be formatted in a multi-user frame format, with a number of long training field (LTF) symbols equal to the number of transmit antennas. In a second implementation, the packet may be a null data packet (NDP), and the device may transmit a separate data packet. In a third implementation, the packet may be formatted in single-user frame format with a modified LTF. A receiving device may receive the packet, and may perform channel estimation and power amplifier (PA) distortion cancellation based on the received packet.

Abstract: This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for combining channel feedback obtained for multiple soundings and transmitting beamformed communications based on the combined channel feedback. In one aspect, a method includes transmitting, by a first wireless device, a first channel sounding using a first subset of antennas, receiving first channel feedback from a second wireless device based on the first channel sounding, transmitting a second channel sounding using a second subset of the antennas that partially overlaps with the first subset, receiving second channel feedback based on the second channel sounding, and transmitting a beamformed communication to the second wireless device based on the first and the second channel feedback.

Abstract: A mechanism for mitigating inter-user interference in a multi-user wireless communication environment is disclosed. A first network device determines a plurality of steering matrices, associated with a corresponding plurality of subcarriers, for each of at least a subset of destination devices associated with the first network device. A phase difference between corresponding steering vectors of each pair of consecutive steering matrices of the plurality of steering matrices associated with each of the subset of destination devices is determined and phase rotation is performed to maintain phase continuity between the consecutive steering matrices. One or more pre-coding matrices are calculated based on at least a subset of the plurality of steering matrices associated with the subset of destination devices. The one or more pre-coding matrices are applied to data to be transmitted to the subset of destination devices to mitigate interference between each of the subset of destination devices.

Abstract: A mechanism for controlling transmit power associated with a plurality of transmit chains of a beamforming transceiver system. A plurality of beamforming steering matrices associated with a plurality of subcarriers of an RF signal received at the transceiver system are generated. A maximum transmit power associated with each of the plurality of transmit chains of the transceiver system is calculated. A power scaling factor for each of the plurality of transmit chains is determined based, at least in part, on the beamforming steering matrices and the maximum transmit power associated with each transmit chain. At least one of the power scaling factors is applied to the plurality of transmit chains to control the transmit power associated with each transmit chain.

Abstract: Transmitting beamforming can steer a transmitting signal to reduce the interference between spaces of a MIMO system and achieves constructive combination at the receiver. One method of steering matrix calculation includes using singular value decomposition (SVD). Notably, the singular values of SVD, which represent the stream strengths in a MIMO system, are in descending order. In equal modulation, signal strength degradation makes the receive EVM of the latest stream poor and increases the probability of packet error. MMSE can be used to weight the steering vectors of the steering matrix calculated in SVD. This weighting of the singular values can balance the SNR of the streams, thereby improving packet error rate.

Abstract: An adjacent channel interference rejection mechanism is provided to detect and reject CCK-modulated signals from an adjacent channel in a wireless communication receiver. Replicas of the baseband signals are frequency-shifted and then analyzed through a series of correlations to compare the power of the correlation outputs. An adjacent channel interference of a CCK-modulated signal is determined and rejected based on the comparisons meeting a predetermined tolerance level.

Abstract: A mechanism for processing beamforming steering matrices in a transceiver system. A plurality of beamforming steering matrices associated with a plurality of subcarriers of an RF signal received at the transceiver system are generated. The beamforming steering matrices are compressed and stored. The beamforming steering matrices may also be grouped or sub-sampled prior to being stored. The beamforming steering matrices are decompressed and ungrouped before being applied to data to be transmitted. Prior to ungrouping the beamforming steering matrices, a phase difference between corresponding beamforming steering vectors of consecutive beamforming steering matrices is determined. Phase rotation is performed on the corresponding beamforming steering vectors based on the determined phase difference associated with the corresponding beamforming steering vectors to improve phase continuity between consecutive beamforming steering matrices.

Abstract: Transmitting beamforming can steer a transmitting signal to reduce the interference between spaces of a MIMO system and achieves constructive combination at the receiver. One method of steering matrix calculation includes using singular value decomposition (SVD). Notably, the singular values of SVD, which represent the stream strengths in a MIMO system, are in descending order. In equal modulation, signal strength degradation makes the receive EVM of the latest stream poor and increases the probability of packet error. MMSE can be used to weight the steering vectors of the steering matrix calculated in SVD. This weighting of the singular values can balance the SNR of the streams, thereby improving packet error rate.

Abstract: A receiver for a wireless communication device comprising a mechanism for performing spur mitigation. A spur mitigation unit of the receiver is operable to determine a current estimate of a spur signal from an ADC output signal using a growing box filter. The spur mitigation unit can determine a power of the current estimate of the spur signal and a power of a previous estimate of the spur signal using a power measurement unit. The spur mitigation unit can determine whether the power of the previous estimate of the spur signal is greater than the power of the current estimate of the spur signal. If the power of the previous spur signal estimate is greater than the power of the current spur signal estimate, the spur mitigation unit can remove the spur signal from the ADC output signal based on the previous spur signal estimate.

Abstract: A mechanism for processing beamforming steering matrices in a transceiver system. A plurality of beamforming steering matrices associated with a plurality of subcarriers of an RF signal received at the transceiver system are generated. The beamforming steering matrices are compressed and stored. The beamforming steering matrices may also be grouped or sub-sampled prior to being stored. The beamforming steering matrices are decompressed and ungrouped before being applied to data to be transmitted. Prior to ungrouping the beamforming steering matrices, a phase difference between corresponding beamforming steering vectors of consecutive beamforming steering matrices is determined. Phase rotation is performed on the corresponding beamforming steering vectors based on the determined phase difference associated with the corresponding beamforming steering vectors to improve phase continuity between consecutive beamforming steering matrices.

Abstract: A mechanism for processing beamforming steering matrices in a transceiver system. A plurality of beamforming steering matrices associated with a plurality of subcarriers of an RF signal received at the transceiver system are generated. The beamforming steering matrices are compressed and stored. The beamforming steering matrices may also be grouped or sub-sampled prior to being stored. The beamforming steering matrices are decompressed and ungrouped before being applied to data to be transmitted. Prior to ungrouping the beamforming steering matrices, a phase difference between corresponding beamforming steering vectors of consecutive beamforming steering matrices is determined. Phase rotation is performed on the corresponding beamforming steering vectors based on the determined phase difference associated with the corresponding beamforming steering vectors to improve phase continuity between consecutive beamforming steering matrices.

Abstract: An adjacent channel interference rejection mechanism is provided to detect and reject CCK-modulated signals from an adjacent channel in a wireless communication receiver. Replicas of the baseband signals are frequency-shifted and then analyzed through a series of correlations to compare the power of the correlation outputs. An adjacent channel interference of a CCK-modulated signal is determined and rejected based on the comparisons meeting a predetermined tolerance level.

Abstract: A receiver for a wireless communication device comprising a mechanism for performing spur mitigation. A spur mitigation unit of the receiver is operable to determine a current estimate of a spur signal from an ADC output signal using a growing box filter. The spur mitigation unit can determine a power of the current estimate of the spur signal and a power of a previous estimate of the spur signal using a power measurement unit. The spur mitigation unit can determine whether the power of the previous estimate of the spur signal is greater than the power of the current estimate of the spur signal. If the power of the previous spur signal estimate is greater than the power of the current spur signal estimate, the spur mitigation unit can remove the spur signal from the ADC output signal based on the previous spur signal estimate.

Abstract: A receiver for a wireless communication device comprising a mechanism for performing spur mitigation. An AGC unit of the receiver is operable to determine when an amplitude of an ADC output signal associated with a received RF signal is outside a predetermined amplitude range. The AGC unit is operable to modify a gain associated with a VGA such that the ADC output signal has an amplitude within the predetermined amplitude rage. The first spur mitigation unit is operable to determine an estimate of a spur signal of the ADC output signal and remove the spur signal from the ADC output signal based on the estimate of the spur signal. The first spur mitigation unit comprises a moving average filter operable to generate the estimate of the spur signal. The AGC unit is further operable to reset the moving average filter of the first spur mitigation unit when the AGC unit modifies the gain associated with the VGA.

Abstract: A mechanism for mitigating inter-user interference in a multi-user wireless communication environment is disclosed. A first network device determines a plurality of steering matrices, associated with a corresponding plurality of subcarriers, for each of multiple destination devices associated with the first network device. A phase difference between corresponding steering vectors of each pair of consecutive steering matrices of the plurality of steering matrices associated with each of the destination devices is determined and phase rotation is performed to maintain phase continuity between the consecutive steering matrices. One or more pre-coding matrices are calculated based on at least a subset of the plurality of steering matrices associated with the multiple destination devices. The one or more pre-coding matrices are applied to data to be transmitted to the multiple destination devices to mitigate interference between each of the multiple destination devices.

Abstract: A mechanism for processing beamforming steering matrices in a transceiver system. A plurality of beamforming steering matrices associated with a plurality of subcarriers of an RF signal received at the transceiver system are generated. The beamforming steering matrices are compressed and stored. The beamforming steering matrices may also be grouped or sub-sampled prior to being stored. The beamforming steering matrices are decompressed and ungrouped before being applied to data to be transmitted. Prior to ungrouping the beamforming steering matrices, a phase difference between corresponding beamforming steering vectors of consecutive beamforming steering matrices is determined. Phase rotation is performed on the corresponding beamforming steering vectors based on the determined phase difference associated with the corresponding beamforming steering vectors to improve phase continuity between consecutive beamforming steering matrices.