Abstract: Certain aspects of the present disclosure relate to methods and apparatus for using information in a Very High Throughput Signal B (VHT-SIG-B) field in the preamble of a null data packet (NDP). Retaining the VHT-SIG-B field in NDPs offers several advantages, such as maintaining a unified IEEE 802.11ac preamble structure, providing for 4 ?s extra time to process beamforming feedback, and being able to use information in the VHT-SIG-B field to determine a level of interference in the NDP.

Abstract: A modified preamble is used by extended devices that operate at higher rates, MIMO or other extensions relative to strict 802.11a-compliant devices. The extended devices might use multiple antenna techniques (MIMO), where multiple data streams are multiplexed spatially and/or multi-channel techniques, where an extended transmitter transmits using more than one 802.11a channel at a time. Such extensions to IEEE 802.11a can exist in extended devices. The modified preamble is usable for signaling, to legacy devices as well as extended devices, to indicate capabilities and to cause legacy devices or extended devices to defer to other devices such that the common communication channel is not subject to unnecessary interference. The modified preamble is also usable for obtaining MIMO channel estimates and/or multi-channel estimates.

Abstract: Systems and/or methods for communication generate a plurality of spatial streams. Each of the spatial streams comprises a plurality of symbols. At least a portion of a training sequence is distributed across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams.

Abstract: Beamforming may be used in MIMO communication systems to further enhance spectral efficiency. Beamforming refers to beamed transmissions to a single destination (e.g., a station) at a time, to enhance the rate and/or range of transmission. To perform beamforming from a source to one or more destinations, a channel and/or beamforming matrices corresponding to the channel needs to be known at the source, which may be obtained as feedback from the destination. However, the beamforming matrices may not be smooth over frequency as it is fed back from the destination. Therefore, certain aspects of the present disclosure provide beamforming feedback options, resulting in the smoothness of a beamforming matrix.

Abstract: Beamforming may be used in MIMO communication systems to further enhance spectral efficiency. Beamforming refers to beamed transmissions to a single destination (e.g., a station) at a time, to enhance the rate and/or range of transmission. To perform beamforming from a source to one or more destinations, a channel and/or beamforming matrices corresponding to the channel needs to be known at the source, which may be obtained as feedback from the destination. However, the beamforming matrices may not be smooth over frequency as it is fed back from the destination. Therefore, certain aspects of the present disclosure provide beamforming feedback options, resulting in the smoothness of a beamforming matrix.

Abstract: Systems and/or methods for communication that generate a plurality of spatial streams are disclosed. Each of the spatial streams comprises a plurality of symbols. At least a portion of a training sequence is distributed across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams.

Abstract: Certain aspects of the present disclosure relate to a technique for communicating supported modulation coding schemes (MCS). In some aspects, the information indicating which MCS are supported for a first communication type is used in part to determine which MCS are supported for a second communication type.

Abstract: A communication device for transmitting a pilot sequence is described. The communication device includes pilot generation circuitry configured for generating a pilot sequence with a reduced peak-to-average power ratio contribution after rotation. The communication device also includes transmitter circuitry configured for transmitting the pilot sequence.

Abstract: Beamforming may be used in MIMO communication systems to further enhance spectral efficiency. Beamforming refers to beamed transmissions to a single destination (e.g., a station) at a time, to enhance the rate and/or range of transmission. To perform beamforming from a source to one or more destinations, a channel and/or beamforming matrices corresponding to the channel needs to be known at the source, which may be obtained as feedback from the destination. However, the beamforming matrices may not be smooth over frequency as it is fed back from the destination. Therefore, certain aspects of the present disclosure provide beamforming feedback options, resulting in the smoothness of a beamforming matrix.

Abstract: Link adaptation is supported in a multi-user MIMO environment. In some aspects, a frame including a transmission parameter request (e.g., a null data packet announcement (NDPA) including a modulation and coding scheme (MCS) request (MRQ)) specifies multiple destinations. In some aspects, a decision to transmit a frame specifying multiple destinations is based on whether all of destinations support providing feedback to such a frame. In some aspects, transmission parameter feedback (e.g., MCS feedback (MFB)) including channel estimate information is provided in a case where MFB of type MU is requested.

Abstract: Link adaptation is supported in a multi-user MIMO environment. In some aspects, a frame including a transmission parameter request (e.g., a null data packet announcement (NDPA) including a modulation and coding scheme (MCS) request (MRQ)) specifies multiple destinations. In some aspects, a decision to transmit a frame specifying multiple destinations is based on whether all of destinations support providing feedback to such a frame. In some aspects, transmission parameter feedback (e.g., MCS feedback (MFB)) including channel estimate information is provided in a case where MFB of type MU is requested.

Abstract: Link adaptation is supported in a multi-user MIMO environment. In some aspects, a frame including a transmission parameter request (e.g., a null data packet announcement (NDPA) including a modulation and coding scheme (MCS) request (MRQ)) specifies multiple destinations. In some aspects, a decision to transmit a frame specifying multiple destinations is based on whether all of destinations support providing feedback to such a frame. In some aspects, transmission parameter feedback (e.g., MCS feedback (MFB)) including channel estimate information is provided in a case where MFB of type MU is requested.

Abstract: A method and apparatus for generating soft-decision output values for a set of transmitted spatial streams in a multiple-input multiple-output (MIMO) communication system are described. The apparatus includes a processor and memory with executable instructions. A plurality of constellation points for respective transmitted spatial streams are looped over to estimate values for other transmitted streams based at least in part on Reduced List Detection (RLD). The plurality of constellation points is a subset of all possible constellation points determined around a spatial stream where more constellation points are assigned to spatial streams with a weaker signal strength than for spatial streams with a stronger signal strength. A set of distance metrics as values of the plurality of constellation points for the respective transmitted spatial streams are determined. Soft-decision outputs for the respective transmitted streams based at least in part on the set of distance metrics are generated.

Abstract: Systems, methods, and devices for performing channel estimates to address the Doppler Effect in wireless communications are described herein. One aspect of the disclosure provides an apparatus for wireless communication. The apparatus comprises a receiver configured to receive coded data tones during a first symbol over a communication channel. The apparatus further comprises a processor. The processor is configured to estimate a common phase offset and amplitude of the communication channel based on pilot tones received over the communication channel. The processor is configured to determine, prior to decoding, a residual phase offset per data tone based on a phase difference between an estimate of the coded data tones and a reference symbol. The processor is configured to estimate update channel state information of the communication channel based on the determined estimated common phase offset, amplitude, and the determined residual phase offset per data tone.

Abstract: Systems and methodologies are described that provide low-complexity soft-output detection for MIMO communication systems. Looping can be performed over a set of constellation points per spatial stream to obtain distance metrics for each of a series of transmitted streams, for which values for the other transmitted streams can be estimated using a MIMO channel matrix and a sub-optimal MIMO algorithm. Examples of MIMO algorithms that can be utilized include Per-Stream List Detection (PSLD), Lattice-Reduced Detection (LRD), and a Guided-M Algorithm. Performance can be further improved by pre-processing the MIMO channel matrix and/or by utilizing techniques for Enhanced Metric Usage (EMU).

Abstract: Systems, methods, and devices for performing clear channel assessment at a receiving device are described herein. In some aspects, the receiving device determines whether it is the intended receiver for a data transmission. Upon determining it is the intended receiver, the receiving device transmits a reservation signal. Devices in the vicinity of the receiving device are configured to listen for the reservation signal and refrain from transmitting interfering signals to the receiving device based on the reservation signal.

Abstract: Systems, methods, and devices for reducing the overhead required to transmit acknowledgment messages (ACKs) are described herein. In some aspects, the ACKs are reduced in size. In some aspects the ACKs include several short training fields. In some aspects, a receiver of the ACKs can determine the transmitter of the ACK based on when the ACK is received. In some aspects, a receiver of the ACKs can determine the transmitter of the ACK based on information superimposed on the short training fields in the ACK.

Abstract: A method for generating a Physical Layer Convergence Protocol Packet Data Unit (PPDU) having a preamble and a payload for television white space transmission (TVWS) is provided. The symbols of the PPDU each include 128 total (orthogonal frequency-division multiplexing) OFDM tones or 256 total OFDM tones. The preamble includes a signal (SIG) field symbol having 108 OFDM data tones if the symbols of the PPDU include 128 total OFDM tones or having 234 OFDM data tones if the symbols of the PPDU include 256 total OFDM tones. The SIG field symbol indicates at least one of an amount of data in the payload or a length of time that the PPDU will occupy the television broadcast frequency spectrum. The PPDU is generated by down-clocking an 802.11ac signal by a factor so that the bandwidth of the PPDU decreases down to one appropriate for use in a TVWS channel.

Abstract: Certain aspects of the present disclosure provide a method for performing interference suppression in spatial division multiple access (SDMA) systems. When the number of receive antennas of a receiver is equal or larger than the number of spatial streams intended for the receiver, the receiver may perform interference suppression on the signals received on all of its antennas. In addition, certain aspects of the present disclosure present a flexible SDMA technique in which a plurality of channel estimates that may be received from an explicit feedback or estimated implicitly, are combined. The combined channel estimate may be used in calculating the SDMA weights.

Abstract: Certain aspects of the present disclosure generally relate to apparatus and methods for switching operating bandwidth and/or operating channel in a wireless communications network. A transmitting STA may send an announcement of a switch to a particular bandwidth in a frame, wherein the presence of absence of a Secondary Channel Offset Element and a Wide Bandwidth Channel Switch Element in the frame indicates whether the particular bandwidth belongs to a first or second set of operating bandwidths. The presence of the Secondary Channel Offset Element and a Wide Bandwidth Channel Switch Element in the frame may indicate a switch to the first set of operating bandwidths. The first set of operating bandwidths may include VHT channels including 80 MHz only, 80+80 MHz and 160 MHz channels. The absence of the Secondary Channel Offset Element and a Wide Bandwidth Channel Switch Element in the frame may indicate a switch to the second set of operating bandwidths.