Abstract: Embodiments of a method and an apparatus for wireless communications are disclosed. In an embodiment, a method for wireless communications involves generating a packet for transmission to a user, where generating the packet includes: encoding user signaling parameters and setting a station-identification (STA-ID) of the user to a value, where the signaling parameters include a number of space time streams (nSTS) spatial streams, establishing a dummy user without changing the user signaling parameters, setting a STA-ID of the dummy user to a value that is different from the STA-ID value of the user, indicating the nSTS spatial streams that are allocated to the dummy user and that are to include Long Training Field (LTF) symbols, and transmitting the packet to the user with the LTF symbols.

Abstract: A receiver receives a wireless signal comprising a plurality of fields including a legacy short training field (L-STF), legacy long training field (L-LTF), and legacy signal (L-SIG) field transmitted to a plurality of antenna of the receiver. For each sub-band in a receiver bandwidth and when samples of the L-STF is received, a first angle based autocorrelation is performed to determine a group of sub-bands which maximize a magnitude based on the first autocorrelations for one or more sub-bands. For each sub-band in the receiver bandwidth and when samples of the L-LTF is received, a second angle based autocorrelation is then performed to refine the crude bandwidth pattern estimate. One or more signal fields and one or more data fields of the received signal are decoded based on the refined bandwidth pattern estimate.

Abstract: One example discloses a method for beamforming feedback reduction in a WLAN (wireless local area network), including: generating a per-tone beamforming feedback matrix by vectorizing a set of steering vectors using vectorization based dimension reduction (DR-Vec); performing lossy compression on the vectors; reducing the per-tone beamforming feedback matrix to one vector; and generating per-tone beamforming angle information using only the one vector.

Abstract: Embodiments of an apparatus and method for wireless communications are disclosed. In an embodiment, a wireless device includes a controller configured to construct an orthogonal matrix, and a wireless transceiver configured to conduct wireless communications based on the orthogonal matrix. The size of the orthogonal matrix is 12×12 or 16×16.

Abstract: A beamformee receives a channel coefficient matrix H of a wireless communication channel between a beamformer and the beamformee. The channel coefficient matrix is a 2×N complex matrix having two rows corresponding to two antenna of the beamformee and N columns corresponding to N antenna of the beamformer. A real symmetric matrix M is determined based on the matrix H followed by determining eigenvalues and eigenvectors of matrix M. Singular vectors of the matrix H based on the eigenvectors are determined where the singular vectors define a steering matrix. The steering matrix is transmitted to a beamformer, wherein a beam is steered by the beamformer to the beamformee based on the steering matrix.

Abstract: A wireless network includes a networking device and various stations. The networking device determines an available bandwidth of each station of the wireless network. Further, the networking device assigns a bandwidth and at least one spatial stream to each station. The bandwidth assigned to each station is less than or equal to the available bandwidth of the corresponding station. Further, the bandwidth assigned to one station is different from and partially overlaps with the bandwidth assigned to another station. Similarly, the spatial stream assigned to one station is different from the spatial stream assigned to another station. The networking device generates a data packet indicative of the bandwidth and the spatial stream assigned to each station of the wireless network, and transmits the data packet to each station to enable multi-user multiple-input-multiple-output (MU-MIMO) communication between the networking device and the stations.

Abstract: Embodiments of a method and an apparatus for wireless communications are disclosed. In an embodiment, a method for wireless communications involves operating an Access Point (AP) using feedback subcarrier indices for a bandwidth up to 320 MHz, signaling, by the AP, to a client, a subcarrier location set on which a feedback report is solicited, signaling, by the AP, to a client, a feedback type solicited on the subcarrier location, and indicating, by the client, feedback subcarrier indices for the subcarrier location set via the feedback report solicited by the AP.

Abstract: A wireless communication device includes first and second links. The first and second links respectively include first and second sets of antennae having an arrangement that renders a null space of a channel matrix between the first and second links non-zero. When the first and second links operate on a first frequency band, the first link obtains first channel state information that indicates a first channel measurement of a first set of channels observed from the second link to the first link. Based on the first channel state information, the first link determines a spatial mapping matrix that facilitates null steering of a signal transmission from the first link in a direction of the second link. The first link transmits to a remote device, a wireless signal on the first frequency band based on the spatial mapping matrix.

Abstract: A WLAN AP includes an array of antennas, a transceiver and a processor. The transceiver is configured to transmit via the array of antennas downlink packets to WLAN STAs, and to receive uplink packets from the STAs. The processor is coupled to the transceiver and is configured to send a request to a plurality of the STAs to transmit a respective plurality of channel-sounding packets corresponding to the plurality of STAs, to receive the plurality of channel-sounding packets from the plurality of STAs in response to the request, to compute, based on the received plurality of channel-sounding packets, a beamforming matrix that defines subsequent transmission beams aimed toward at least a subset of the plurality of STAs, and to transmit one or more downlink data packets to one or more of the STAs via the array of antennas, in accordance with the beamforming matrix.

Abstract: A wireless network includes a networking device and various stations. The networking device determines an available bandwidth of each station of the wireless network. Further, the networking device assigns a bandwidth and at least one spatial stream to each station. The bandwidth assigned to each station is less than or equal to the available bandwidth of the corresponding station. Further, the bandwidth assigned to one station is different from and partially overlaps with the bandwidth assigned to another station. Similarly, the spatial stream assigned to one station is different from the spatial stream assigned to another station. The networking device generates a data packet indicative of the bandwidth and the spatial stream assigned to each station of the wireless network, and transmits the data packet to each station to enable multi-user multiple-input-multiple-output (MU-MIMO) communication between the networking device and the stations.

Abstract: Embodiments of a method and an apparatus for beamforming are disclosed. In an embodiment, a method for beamforming involves transmitting, by a beamformer to a beamformee, a sounding packet that includes training symbols, receiving, at the beamformee, the sounding packet that includes the training symbols, deriving, at the beamformee, channel estimates from the training symbols included in the sounding packet, computing, at the beamformee, a feedback matrix from the derived channel estimates, transmitting, by the beamformee to the beamformer, a packet that includes two sets of symbols, where the feedback matrix is applied to at least one of the two sets of symbols, receiving, at the beamformer, the packet that includes the two sets of symbols, and operating the beamformer according to the two sets of symbols included in the packet.

Abstract: A wireless communication device includes first and second links. The first and second links respectively include first and second sets of antennae having an arrangement that renders a null space of a channel matrix between the first and second links non-zero. When the first and second links operate on a first frequency band, the first link obtains first channel state information that indicates a first channel measurement of a first set of channels observed from the second link to the first link. Based on the first channel state information, the first link determines a spatial mapping matrix that facilitates null steering of a signal transmission from the first link in a direction of the second link. The first link transmits to a remote device, a wireless signal on the first frequency band based on the spatial mapping matrix.

Abstract: Wi-Fi communication is further secured by perturbation of a spatial mapping matrix. In an embodiment channel state information is obtained from a receiving device in a wireless network through the wireless network. A first set of beam steering vectors is derived based on the channel state information to direct a radio signal to the receiving device. A second set of beam steering vectors is derived based on the channel state information to direct a radio signal other than to the receiving device. A perturbation matrix is generated. A spatial mapping matrix is formed by combining the first and the second set of beam steering vectors with a perturbation matrix. Data symbols to be transmitted are pre-coded to the receiving device using the spatial mapping matrix and transmitted through the wireless network to the receiving device.

Abstract: A beamformer generates a null data packet (NDP) that includes various long training fields (LTFs). The beamformer generates the NDP based on a spatial mapping matrix that is a product of two matrices. One matrix has a number of rows equal to a number of antennas of the beamformer, and a number of columns equal to a number of LTFs in the NDP. Further, the other matrix has a number of rows and a number of columns equal to the number of LTFs in the NDP. The number of LTFs in the NDP is greater than a number of antennas of the beamformer. Further, the beamformer transmits the NDP to a beamformee to obtain channel state information associated with a channel between the beamformer and the beamformee, and enable beamforming therebetween.

Abstract: Wi-Fi communication is further secured by perturbation of a spatial mapping matrix. In an embodiment channel state information is obtained from a receiving device in a wireless network through the wireless network. A first set of beam steering vectors is derived based on the channel state information to direct a radio signal to the receiving device. A second set of beam steering vectors is derived based on the channel state information to direct a radio signal other than to the receiving device. A perturbation matrix is generated. A spatial mapping matrix is formed by combining the first and the second set of beam steering vectors with a perturbation matrix. Data symbols to be transmitted are pre-coded to the receiving device using the spatial mapping matrix and transmitted through the wireless network to the receiving device.

Abstract: A beamformee executes a singular value decomposition operation on a channel coefficient matrix to generate a diagonal matrix and a unitary matrix. The beamformee extracts a submatrix from each of the diagonal matrix and the unitary matrix. Each of a number of rows and a number of columns of the submatrix extracted from the diagonal matrix is equal to a number of spatial streams associated with a beamformer. Further, the submatrix extracted from the unitary matrix has a number of rows and a number of columns equal to a number of beamformer antennas of the beamformer and the number of spatial streams, respectively. The beamformee generates a subspace matrix that is a product of the submatrix extracted from the diagonal matrix and a conjugate transpose of the submatrix extracted from the unitary matrix. Further, the beamformee generates a steering matrix based on the subspace matrix.

Abstract: The instant invention concerns the use of a compound of formula R1R2N—(CH2)m?NR3—(CH2)m??NR4R5 wherein each of m and m? is 1, 2, 3 or 4; and each of R1, R2, R3, R4 and R5 is a group of formula —[O—CH2—CH(—CH3)—]n—[O—CH2—CH2]p—OH, wherein n is from 2 to 30; and p is from 5 to 50 for decreasing or inhibiting the anionic-surfactant retention phenomena in an oil reservoir.

Abstract: A method for signal transmission includes generating a sequence of modulated symbols, each modulated symbol including multiple sub-carriers having respective sub-carrier frequencies, by (i) designating a first subset of the sub-carriers to serve as non-pilot sub-carriers, and designating a second subset of the sub-carriers to serve as pilot sub-carriers, (ii) modulating non-pilot information onto the non-pilot sub-carriers, and modulating pilot information onto the pilot sub-carriers, and (iii) in at least some of the symbols, setting the non-pilot sub-carriers to a first power level, and setting one or more of the pilot sub-carriers to a second power level that is higher than the first power level. The sequence of the modulated symbols is transmitted over a communication channel to a receiver.

Abstract: Embodiments of a method and an apparatus for wireless communications are disclosed. In an embodiment, a method for wireless communications involves generating a packet for transmission to a user, where generating the packet includes: encoding user signaling parameters and setting a station-identification (STA-ID) of the user to a value, where the signaling parameters include a number of space time streams (nSTS) spatial streams, establishing a dummy user without changing the user signaling parameters, setting a STA-ID of the dummy user to a value that is different from the STA-ID value of the user, indicating the nSTS spatial streams that are allocated to the dummy user and that are to include Long Training Field (LTF) symbols, and transmitting the packet to the user with the LTF symbols.

Abstract: Embodiments of a method and an apparatus for beamforming are disclosed. In an embodiment, a method for beamforming involves transmitting, by a beamformer to a beamformee, a sounding packet that includes training symbols, receiving, at the beamformee, the sounding packet that includes the training symbols, deriving, at the beamformee, channel estimates from the training symbols included in the sounding packet, computing, at the beamformee, a feedback matrix from the derived channel estimates, transmitting, by the beamformee to the beamformer, a packet that includes two sets of symbols, where the feedback matrix is applied to at least one of the two sets of symbols, receiving, at the beamformer, the packet that includes the two sets of symbols, and operating the beamformer according to the two sets of symbols included in the packet.