Abstract: Certain embodiments of the present disclosure provide techniques for approximate computation of l2 norms as a part of the maximum likelihood (ML) detection: tri-maxmin, maxsum and sortsum algorithms. The proposed approximation schemes show better accuracy than conventional approximation schemes—the abssum and maxmin algorithms, while the computational complexity is very similar. The error rate performance of the ML detection that utilizes proposed norm-approximation techniques are very close to the reference ML detection with exact calculation of l2 norms, while the computational complexity is significantly smaller.

Abstract: A base station for communicating with multiple groups of wireless communication devices is described. The base station includes a processor and executable instructions stored in memory that is in electronic communication with the processor. The base station determines a number of wireless communication devices. The base station also splits the number of wireless communication devices into groups. The base station further determines a precoding matrix for each group. The base station additionally transmits a beamformed signal to each group using the precoding matrix for each group.

Abstract: Calibration coefficients are combined to provide more robust calibration. In some implementations, calibration coefficients are generated by acquiring two or more sets of calibration coefficients that are associated with different periods of time, different receive devices, or some other condition. These different sets of calibration coefficients are then combined using maximal ratio combining or some other suitable technique. The resulting combined calibration coefficients are used to calibrate implicit channel estimates.

Abstract: Certain aspects of the present disclosure propose transmitting a feedback message to an access point. The feedback may comprise a beamforming extension field, which may carry per tone signal to noise ratio of a station. For certain aspects, the station transmitting the per-tone SNR may be a single user (SU)-capable device. For certain aspects, the station may indicate to the access point whether or not it has a maximum likelihood (ML) receiver.

Abstract: Certain aspects of the present disclosure provide techniques and apparatus for generating a unified format of channel state information (CSI) feedback for Very High Throughput (VHT) wireless systems. One example method generally includes generating, at a first apparatus, a frame comprising information relating to SNR if a second apparatus is communicating with the first apparatus using single-user MIMO (SU-MIMO) or multi-user MIMO (MU-MIMO) and transmitting a signal based on the generated frame to the second apparatus. Another example method generally includes generating, at an apparatus, a structure comprising CSI, wherein the CSI includes one of a first matrix with estimates of a channel associated with the apparatus or a second matrix obtained based on singular value decomposition (SVD) of the first matrix and wherein the structure further comprises an indication of which of the first and second matrices is included in the CSI; and transmitting the structure over the channel.

Abstract: Methods, systems, and/or devices are provided that permit data transmissions over unused television channels. An unused channel within a television broadcast frequency spectrum is first identified. A downclocked waveform (for data transmission) is then generated by applying a factor to a clock that causes a waveform bandwidth to be reduced from a first bandwidth to a second bandwidth, wherein the second bandwidth of the downclocked waveform is less than a channel bandwidth for the identified unused channel. The downclocked waveform may then be configured so that it coexists with a larger waveform having a third bandwidth that is greater than the channel bandwidth. The downclocked waveform is then wirelessly transmitted from the transmitter device over the identified unused channel.

Abstract: Methods and apparatus for orthogonal pilot tone mapping in Multiple-In and Multiple-Out (MIMO) and Spatial Division Multiple Access (SDMA) systems are disclosed.

Abstract: Methods, systems, and/or devices are provided that permit data transmissions over unused television channels. An unused channel within a television broadcast frequency spectrum is first identified. A downclocked waveform (for data transmission) is then generated by applying a factor to a clock that causes a waveform bandwidth to be reduced from a first bandwidth to a second bandwidth, wherein the second bandwidth of the downclocked waveform is less than a channel bandwidth for the identified unused channel. The downclocked waveform may then be configured so that it coexists with a larger waveform having a third bandwidth that is greater than the channel bandwidth. The downclocked waveform is then wirelessly transmitted from the transmitter device over the identified unused channel.

Abstract: Certain aspects of the present disclosure relate to techniques that may be used to help control aspects of beamforming by a beamformee. According to certain aspects, a beamformee may be able to signal, to a beamformer, a maximum number of transmit spatial streams to use for single-user beamformed transmissions.

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 the channel or a beamforming matrix corresponding to the channel.

Abstract: Certain aspects of the present disclosure provide techniques and apparatus for frequency interleaving for use with 80 MHz transmissions, such as those in the IEEE 802.11ac amendment to the IEEE 802.11 standard. According to certain aspects, frequency interleaving spatial streams for transmissions on channels having widths of about 80 MHz may comprise using an interleaving depth of 26. The number of frequency rotations may be 58 (or 29) for up to four (or up to eight) spatial streams. According to certain aspects, frequency interleaving up to eight (or up to four) spatial streams for transmission on channels having widths of about 80 MHz may comprise performing frequency rotation for each of the spatial streams based on a frequency rotation index=[0 4 2 6 1 5 3 7] (or=[0 2 1 3]).

Abstract: Certain aspects of the present disclosure relate to techniques for transmitting sounding feedback in Very High Throughput (VHT) wireless systems. The sounding feedback may be transmitted from a user station (STA), wherein the feedback may comprise a certain number of beamforming matrices and a certain number of singular values of a wireless channel associated with the STA. Further, the sounding feedback may comprise a bit for indicating whether this feedback represents a Single-User (SU) feedback or a Multi-User (MU) feedback.

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: A communication device for transmitting beamformed signals using implicit channel sounding is described. The communication device includes a processor and instructions stored in memory. The communication device receives one or more sounding signals and computes a channel estimate based on the one or more sounding signals. Frequency offset compensation is applied to the channel estimate by the communication device. The communication device also computes a precoding matrix based on the channel estimate and transmits a beamformed signal using the precoding matrix. Another communication device for receiving beamformed signals using explicit channel sounding is also described. The communication device includes a processor and instructions stored in memory. The communication device receives one or more sounding signals, computes a channel estimate based on the one or more sounding signals and applies amplitude compensation to the channel estimate.

Abstract: Certain aspects of the present disclosure relate to techniques for constructing a VHT-SIG field of a transmission preamble in a manner that may reduce peak-to-average power ratio (PAPR) of the transmission.

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: Certain aspects of the present disclosure relate to a technique of ordering sub-fields within Signal (SIG) fields of a preamble in Very High Throughput (VHT) wireless communications systems and to a technique of managing sizes of these sub-fields.

Abstract: In a downlink multi-user multiple input multiple output (DL MU-MIMO) system, channel state information (CSI) feedback duration may strongly affect media access control (MAC) efficiency. While a time domain compression may give a significant reduction in feedback duration, the time domain compression may have complexity issues at the station (STA). In particular, for time domain compression, a large complex matrix multiplication may be required at the client to estimate a cyclic prefix (CP) length impulse response, which best models the frequency response of the channel. Embodiments of the invention comprise a hybrid scheme that may reduce the above complexity while maintaining significant compression gains.

Abstract: Methods and apparatus for transmitting and receiving frames with various Very High Throughput Signal B (VHT-SIG-B) and Service field formats are provided. Some of these formats may be in accordance with the IEEE 802.11ac amendment to the wireless local area network (WLAN) standard.

Abstract: A communication device for generating a matrix-mapped sequence is described. The communication device includes sequence generation circuitry. The communication device also includes mapping circuitry coupled to the sequence generation circuitry. The mapping circuitry applies a first matrix with at least one column multiplied by ?1 to a sequence. The communication device also includes a transmit block coupled to the mapping circuitry.