Abstract: Embodiments describe methods, systems, and devices that utilize positional information to determine location of other device and/or to provide a location-based message. A method can include receiving a location information of a mobile device and using an access point to transmit location information to one or more other devices that do not include location functionality that are in communication with the mobile device. The method can further include transmitting a message to the mobile device based at least in part on the received access location information. In another embodiment, the method can include receiving a user preference data from the mobile device or one or more other devices and transmitting a communication to the mobile device or one or more other devices that conforms to the user preference data.

Abstract: Mesh Network Access Points (APs) points, including gateways and routers, are deployed over a geographic area. The APs monitor the communication channel for other carriers and transmit accordingly. The APs selectively co-transmit when other carriers are sensed, if the efficiency of the mesh network will improve. APs select a transmission rate based on observed carrier-to-interference ratios. APs use directional antennas to increase carrier-to-interference ratios and spectral efficiency. AP transmit schedules are adaptable and adjusted according to observed carrier-to-interference measurements.

Abstract: Mesh Network Access Points (APs) points, including gateways and routers, are deployed over a geographic area. The APs monitor the communication channel for other carriers and transmit accordingly. The APs selectively co-transmit when other carriers are sensed, if the efficiency of the mesh network will improve. APs select a transmission rate based on observed carrier-to-interference ratios. APs use directional antennas to increase carrier-to-interference ratios and spectral efficiency. AP transmit schedules are adaptable and adjusted according to observed carrier-to-interference measurements.

Abstract: Mesh Network Access Points (APs) points, including gateways and routers, are deployed over a geographic area. The APs monitor the communication channel for other carriers and transmit accordingly. The APs selectively co-transmit when other carriers are sensed, if the efficiency of the mesh network will improve. APs select a transmission rate based on observed carrier-to-interference ratios. APs use directional antennas to increase carrier-to-interference ratios and spectral efficiency. AP transmit schedules are adaptable and adjusted according to observed carrier-to-interference measurements.

Abstract: In a MIMO system, rate control is achieved with an inner loop that selects rates for data streams sent via a MIMO channel and an outer loop that regulates the operation of the inner loop. For the inner loop, SNR estimates are obtained for each data stream based on received pilot symbols and/or received data symbols. An effective SNR is derived for each data stream based on the SNR estimates, a diversity order, a MIMO backoff factor, and an outer loop backoff factor for the data stream. The rates are then selected for the data streams based on the effective SNRs for the data streams. The outer loop adjusts the outer loop backoff factor for each data stream based on the performance (e.g., packet errors and/or decoder metrics) for the data stream.

Abstract: Mesh Network Access Points (APs) points, including gateways and routers, are deployed over a geographic area. The APs monitor the communication channel for other carriers and transmit accordingly. The APs selectively co-transmit when other carriers are sensed, if the efficiency of the mesh network will improve. APs select a transmission rate based on observed carrier-to-interference ratios. APs use directional antennas to increase carrier-to-interference ratios and spectral efficiency. AP transmit schedules are adaptable and adjusted according to observed carrier-to-interference measurements.

Abstract: A method of phase correction at a wireless device includes: estimating a phase slope for an OFDM symbol in a data portion of a packet based on an elapsed time from the start of the packet; measuring a residual phase slope from tracking pilots for the OFDM symbol in the data portion of the packet; and adjusting a phase correction based upon the phase slope and the residual phase slope. Apparatus in a wireless device performs the method and machine-readable media carry instructions for carrying out the method.

Abstract: Embodiments for bandwidth allocation methods, detecting interference with other systems, and/or redeploying in alternate bandwidth are described. Higher bandwidth channels may be deployed at channel boundaries (410), which are a subset of those for lower bandwidth channels (310), and may be restricted from overlapping. Interference may be detected (930) on primary, secondary, or a combination of channels, and may be detected in response to energy measurements (910) of the various channels. When interference is detected, a higher bandwidth Basic Service Set (BSS)(100) may be relocated to an alternate channel, or may have its bandwidth reduced to avoid interference. Interference may be detected based on energy measured on the primary or secondary channel, and/or a difference between the two. An FFT (1010) may be used in energy measurement in either or both of the primary and secondary channels. Stations may also monitor messages from alternate systems to make channel allocation decisions.

Abstract: A method for identifying a reference point in time in a wireless communication system includes: receiving a first repeated sequence of symbols; receiving a second repeated sequence of symbols; performing an autocorrelation between the first and second sequences of symbols; and identifying as the reference point in time an autocorrelation null between the first and second repeated sequences of symbols. Apparatus for identifying a reference point in time in a wireless communication system includes: means for receiving a first repeated sequence of symbols; means for receiving a second repeated sequence of symbols; means for performing an autocorrelation between the first and second sequences of symbols; and means for identifying as the reference point in time an autocorrelation null between the first and second repeated sequences of symbols. Other aspects, features, and embodiments are also claimed and described.

Abstract: Techniques for extending transmission range in a WLAN are described. In an aspect, a receiving station determines the frequency error between a transmitting station and the receiving station based on one or more initial packet transmissions and corrects this frequency error for subsequent packet transmissions received from the transmitting station. The residual frequency error is small after correcting for the frequency error and allows the receiving station to perform coherent accumulation/integration over a longer time interval to detect for a packet transmission. The longer coherent accumulation interval improves detection performance, especially at low SNRs for extended transmission range. The techniques may be used whenever the receiving station knows the identity of the transmitting station, e.g., if the subsequent packet transmissions are scheduled. In another aspect, a preamble is generated with a longer spreading sequence and sent with each packet transmission.

Abstract: A power-efficient wireless device is equipped with multiple (N) antennas. Each antenna is associated with a transmitter unit and a receiver unit. The wireless device also has processing units used to perform various digital processing tasks. The transmitter units, receiver units, and processing units may be selectively enabled or disabled. In an idle state, the wireless device may enable only a subset (e.g., one) of the N receiver units and one or few processing units for signal detection and acquisition. For active communication, the wireless device may enable Ntx transmitter units for data transmission and/or Nrx receiver units for data reception, where 1?Ntx?N and 1?Nrx?N. The enabled processing units may also be clocked at a lower frequency whenever data is transmitted or received at a data rate lower than the highest data rate. The wireless device may go to sleep whenever possible to conserve power.

Abstract: A transmitting entity transmits a “base” pilot in each protocol data unit (PDU). A receiving entity is able to derive a sufficiently accurate channel response estimate of a MIMO channel with the base pilot under nominal (or most) channel conditions. The transmitting entity selectively transmits an additional pilot if and as needed, e.g., based on channel conditions and/or other factors. The additional pilot may be adaptively inserted in almost any symbol period in the PDU. The receiving entity is able to derive an improved channel response estimate with the additional pilot. The transmitting entity sends signaling to indicate that additional pilot is being sent. This signaling may be embedded within pilot symbols sent on a set of pilot subbands used for a carrier pilot that is transmitted across most of the PDU. The signaling indicates whether additional pilot is being sent and possibly other pertinent information.

Abstract: A method for identifying a reference point in time in a wireless communication system includes: receiving a first repeated sequence of symbols; receiving a second repeated sequence of symbols; performing an autocorrelation between the first and second sequences of symbols; and identifying as the reference point in time an autocorrelation null between the first and second repeated sequences of symbols. Apparatus for identifying a reference point in time in a wireless communication system includes: means for receiving a first repeated sequence of symbols; means for receiving a second repeated sequence of symbols; means for performing an autocorrelation between the first and second sequences of symbols; and means for identifying as the reference point in time an autocorrelation null between the first and second repeated sequences of symbols.

Abstract: Techniques for efficiently computing spatial filter matrices are described. The channel response matrices for a MIMO channel may be highly correlated if the channel is relatively static over a range of transmission spans. In this case, an initial spatial filter matrix may be derived based on one channel response matrix, and a spatial filter matrix for each transmission span may be computed based on the initial spatial filter matrix and a steering matrix used for that transmission span. The channel response matrices may be partially correlated if the MIMO channel is not static but does not change abruptly. In this case, a spatial filter matrix may be derived for one transmission span l and used to derive an initial spatial filter matrix for another transmission span m. A spatial filter matrix for transmission span m may be computed based on the initial spatial filter matrix, e.g., using an iterative procedure.

Abstract: Embodiments for bandwidth allocation methods, detecting interference with other systems, and/or redeploying in alternate bandwidth are described. Higher bandwidth channels may be deployed at channel boundaries, which are a subset of those for lower bandwidth channels, and may be restricted from overlapping. Interference may be detected on primary, secondary, or a combination of channels, and may be detected in response to energy measurements of the various channels. When interference is detected, a higher bandwidth Basic Service Set (BSS) may be relocated to an alternate channel, or may have its bandwidth reduced to avoid interference. Interference may be detected based on energy measured on the primary or secondary channel, and/or a difference between the two. An FFT may be used in energy measurement in either or both of the primary and secondary channels. Stations may also monitor messages from alternate systems to make channel allocation decisions. Various other aspects are also presented.

Abstract: A “unified” MIMO system that supports multiple operating modes for efficient data transmission is described. Each operating mode is associated with different spatial processing at a transmitting entity. For example, four operating modes may be defined for (1) full-CSI or partial-CSI transmission and (2) with or without steering transmit diversity (STD). An appropriate operating mode may be selected for use based on various factors (e.g., availability of a good channel estimate). With steering transmit diversity, data is spatially spread and transmitted on multiple spatial channels, and a single rate may then be used for all spatial channels used for data transmission. A receiving entity may utilize a minimum mean square error (MMSE) technique for all operating modes. The receiving entity may derive a spatial filter matrix and perform receiver spatial processing in the same manner for all operating modes, albeit with different effective channel response matrices.

Abstract: A receiving entity obtains received symbols for a data transmission having at least one data symbol stream sent with space-time transmit diversity (STTD). The receiving entity derives an overall channel response matrix in accordance with the STTD encoding scheme used for the data transmission, derives a spatial filter matrix based on the overall channel response matrix, and performs spatial matched filtering on a vector of received symbols for each 2-symbol interval to obtain a vector of detected symbols for the 2-symbol interval. The receiving entity may perform post-processing (e.g., conjugation) on the detected symbols if needed. Alternatively, the receiving entity derives a spatial filter matrix based on an effective channel response matrix, performs spatial matched filtering on the received symbols for each symbol period to obtain detected symbols for that symbol period, and combines multiple estimates obtained for each data symbol sent with STTD.

Abstract: For data transmission with spatial spreading, a transmitting entity (1) encodes and modulates each data packet to obtain a corresponding data symbol block, (2) multiplexes data symbol blocks onto NS data symbol streams for transmission on NS transmission channels of a MIMO channel, (3) spatially spreads the NS data symbol streams with steering matrices, and (4) spatially processes NS spread symbol streams for full-CSI transmission on NS eigenmodes or partial-CSI transmission on NS spatial channels of the MIMO channel. A receiving entity (1) obtains NR received symbol streams via NR receive antennas, (2) performs receiver spatial processing for full-CSI or partial-CSI transmission to obtain NS detected symbol streams, (3) spatially despreads the NS detected symbol streams with the same steering matrices used by the transmitting entity to obtain NS recovered symbol streams, and (4) demodulates and decodes each recovered symbol block to obtain a corresponding decoded data packet.

Abstract: Techniques for decomposing matrices using Jacobi rotation are described. Multiple iterations of Jacobi rotation are performed on a first matrix of complex values with multiple Jacobi rotation matrices of complex values to zero out the off-diagonal elements in the first matrix. For each iteration, a submatrix may be formed based on the first matrix and decomposed to obtain eigenvectors for the submatrix, and a Jacobi rotation matrix may be formed with the eigenvectors and used to update the first matrix. A second matrix of complex values, which contains orthogonal vectors, is derived based on the Jacobi rotation matrices. For eigenvalue decomposition, a third matrix of eigenvalues may be derived based on the Jacobi rotation matrices. For singular value decomposition, a fourth matrix with left singular vectors and a matrix of singular values may be derived based on the Jacobi rotation matrices.

Abstract: Techniques for performing sphere detection to recover data symbols sent in a MIMO transmission are described. In an aspect, sphere detection is performed for data symbols generated with at least two modulation schemes. In another aspect, sphere detection is performed for the data symbols in an order determined based on at least one attribute of the data symbols, which may be error probabilities, modulation schemes, and/or link margins for the data symbols. In yet another aspect, rates for multiple data streams detected with sphere detection are selected based on channel state information. Signal qualities of the data streams may be estimated based on the channel state information, e.g., (1) an upper triangular matrix used for sphere detection and/or (2) an assumption that interference from data streams already detected is canceled. The rates for the data streams may be selected based on the estimated signal qualities.