Patent application number | Description | Published |
20080205539 | Method and System for Achieving Spatial Diversity of a Wireless Communications Network - A method and system are provided for achieving spatial diversity of a wireless communications network. The method comprises arranging antennas on a transmitting wireless station into a plurality of antenna subgroups, wherein each of the antenna subgroups forms a virtual antenna, creating a plurality of beamformed MIMO channels using the plurality of virtual antennas, wherein each of the beamformed MIMO channel comprises a plurality of sub-carriers and corresponds to a virtual antenna, dividing sub-carriers in each of the plurality of beamformed MIMO channels into at least a first and second cluster, distributing a first amount of transmitting power to the first cluster and a second amount of transmitting power to the second cluster, wherein the first amount of transmitting power is substantially larger than the second amount of transmitting power. | 08-28-2008 |
20080240208 | Adaptive Switching Techniques for Hybrid Automatic Repeat Request Systems - Apparatus, system, and method for an adaptive transmission selection technique. A retransmission scheme is selected for a multiple-input-multiple-output (MIMO) wireless communications system. Techniques are provided herein for selecting from a plurality of wireless communication techniques when a first device needs to retransmit a signal (one or more packets of data) to a second device. The first device determines when the signal which was originally wirelessly transmitted using beamforming techniques via multiple antennas of the first device to the second device needs to be retransmitted to the second device. If a retransmission is needed, the first device determines channel conditions with respect to the second device. The first device selects a retransmission scheme from a plurality of transmission schemes based on the channel conditions for retransmitting the signal via the multiple antennas of the first device to the second device. A first retransmission technique is selected when the channel conditions are static. A second retransmission technique is selected when the channel conditions are relatively slowly changing, and a third retransmission technique is selected when the channel conditions are relatively quickly changing. | 10-02-2008 |
20080320355 | System for Identifying Localized Burst Errors - A system for detecting one or more localized burst errors in a receiving message comprised of a plurality of codewords. The system comprises a trellis code decoder for decoding a receiving message with a plurality of codewords and calculating one or more cumulative metrics of a maximum likelihood path and one or more alternative paths from the receiving message, an error detection code (EDC) decoder for detecting existence of one or more errors in the decoded receiving message received from the trellis decoder, and a localized burst error detector activated by the EDC decoder upon detecting the existence of one or more errors in the decoded receiving message to identify at least one corrupted codeword among the plurality of codewords using the one or more cumulative metrics of a maximum likelihood path and the one or more alternative paths, wherein the system requests the re-transmission of the corrupted codeword. | 12-25-2008 |
20090042618 | GENERALIZED MIMO-BEAMFORMING WEIGHT ESTIMATION - Techniques are provided to enable wireless communication between first and second wireless communication devices each having a plurality of antennas, where the second device sends the transmissions via less than all of its plurality of antennas. Each transmission may comprise a plurality of time-frequency instances. At the first communication device, data is derived representing parameters of a communication channel between the plurality of antennas of the first device and all of the plurality of antennas of the second device from the transmissions received at the plurality of antennas of the first device. Beamforming weights for transmitting one or more signal streams via the plurality of antennas of the first device to the plurality of antennas of the second device are computed based on the data representing parameters of the communication channel between the plurality of antennas of the first device and the plurality of antennas of the second device. The beamforming weights are applied to the one or more signal streams to be transmitted via the plurality of antennas of the first device to the plurality of antennas of the second device. | 02-12-2009 |
20090086855 | LINK ADAPTATION BASED ON GENERIC CINR MEASUREMENT ACCORDING TO LOG-LIKELIHOOD RATIO DISTRIBUTION - Techniques are provided to compute the carrier to interference-plus-noise ratio (CINR) in a wireless communication system using log-likelihood ratio (LLR) data generated from a received transmission. The LLR data are collected as they are sent from a detector to a forward error correction (FEC) decoder in a wireless communications device. In one embodiment, decision-aided LLR based CINR is computed using the decoded bits output from the FEC decoder as feedback. In another embodiment, blind LLR based CINR is computed without feedback. The CINR may be used to adjust a modulation and/or coding parameters associated with wireless communication between wireless communication devices. | 04-02-2009 |
20090135938 | PERFORMANCE OF A TRELLIS-BASED DECODER USING STATES OF REDUCED UNCERTAINTY - A method and system are provided for improving the performance of a trellis-based decoder. States with reduced uncertainty (SRUs) are defined for one or more predetermined fields in an encoded message. Metrics are set for the SRUs such that candidate paths through a trellis-based decoding process are eliminated for those states that are not SRUs. | 05-28-2009 |
20110013708 | Signal Sequence Detection Techniques for OFDM/OFDMA Systems - Energy in a frequency band is received at a wireless communication device and data is generated representing samples of a received time domain waveform from the received energy. Data for groups of samples of the received time domain waveform is processed to transform the data for the received time domain waveform to produce data for an intermediate domain signal that is in neither the time domain nor the frequency domain. The data representing the intermediate domain signal is analyzed to determine whether a sequence having a predetermined pattern from a set of possible sequences is present in the received energy, and ultimately to determine a sequence of the predetermined pattern whose presence is detected in the received energy. | 01-20-2011 |
20110013711 | Beamforming Weight Estimation Using Wideband Multipath Direction of Arrival Analysis - Techniques are provided for computing downlink beamforming weights based on the received data at a base station from a mobile station in a MIMO communication system. An uplink transmission is received at a plurality of antennas at a first communication device from a second communication device, where the uplink transmission comprises a plurality of uplink subbands. The uplink spatial signature is estimated for each of the plurality of uplink subbands. The uplink spatial signature is decomposed into a plurality of direction of arrival (DOA) components for each uplink subband using a transform. Data representing multiple propagation paths between the first communication device and the second communication device is computed for each DOA component. A plurality of direction of departure (DOD) components for each of a plurality of downlink subbands is computed based on the data representing the multiple propagation paths. A downlink spatial signature for each downlink subband from the plurality of DOD components is computed using an inverse of the transform. Downlink beamforming weights are computed for each of the plurality of downlink subbands based on the downlink spatial signature, where the downlink beamforming weights are for use by the first communication device when beamforming a downlink transmission via the plurality of antennas of the first communication device to the second communication device. | 01-20-2011 |
20110090974 | Scheduling Collaborative Uplink Transmissions in OFDMA Systems Using Multipath Direction of Arrival Analysis - Techniques are provided for receiving uplink transmissions at a plurality of antennas at a base station from a plurality of client stations. Uplink spatial transmissions are analyzed to produce a plurality of direction of arrival (DOA) components associated with the plurality of client stations. The DOA components associated with the plurality of client stations are compared and two or more client stations are selected to participate in an uplink collaborative spatial multiplexing transmission session based on dissimilarities of their DOA components. | 04-21-2011 |
20120082262 | ADAPTIVE CLIPPING OF SYMBOLS BASED ON SIGNAL QUALITY - Techniques are provided for crest factor reduction of a symbol to be transmitted by a communication device. The symbol may be an orthogonal frequency division multiplexed (OFDM) formatted symbol. In a communication device, samples of the symbol are clipped with a clipping level. A signal quality of the symbol is computed after it is clipped. A determination is made as to whether the signal quality satisfies a predetermined criterion. When the signal quality does not satisfy the predetermined criterion, the clipping level is adjusted. The clipping, computing, determining and adjusting operations are repeated until the signal quality satisfies the predetermined criterion. The symbol clipped by the clipping level determined to result in satisfying the predetermined criterion is output for supply to a transmitter in the communication device. Techniques for computing for error vector magnitude that are faster and less computationally intensive are provided, as well as a computation for distortion that can be used as a measure of error vector magnitude. | 04-05-2012 |
20120106426 | BANDWIDTH INDICATION IN RTS/CTS FRAMES - Disclosed in an example embodiment is an apparatus comprising a transmitter and processing logic coupled with the transmitter. The processing logic is configured to send data via the transmitter. The processing logic generates a request to send frame. The processing logic encodes data representative of a bandwidth parameter set in the request to send frame. The processing logic transmits the request to send frame via the transmitter. | 05-03-2012 |
20120147804 | Medium Reservation Techniques for Multi-User Transmissions - Techniques are provided for a multi-user reservation sequence used when transmitting a multi-user transmission in a wireless network. At a wireless access point device configured to operate in a wireless network, a multi-user request-to-send packet is transmitted as part of a multi-user reservation sequence prior to a multi-user transmission from the wireless access point device to a plurality of wireless client devices that are the intended recipients for the multi-user transmission. The multi-user request-to-send packet comprises duration information and address information configured to address at least some of the plurality of wireless client devices. Clear-to-send packets transmitted from two or more of the plurality of wireless client devices in response to the multi-user request-to-send packet are received at the wireless access point device. Each clear-to-send packet comprises identical content. In some scenarios, the multi-user request-to-send packet is preceded by a single-user request-to-send packet directed to a designated wireless client device. | 06-14-2012 |
20120314583 | COEXISTENCE MECHANISM FOR MULTIPLE CHANNELS - In accordance with an example embodiment, there is disclosed herein a coexistence mechanism for multiple channels. A plurality of channels are monitored to determine which channels are available for communications. Upon receiving a request to establish communications on a channel set within the plurality of channels, a response is sent to the request on at least one in the channel set. The response comprises data representative of which channels from the channel set are available for communications. Optionally, the response may include data indicating how long the unavailable channels will be occupied. | 12-13-2012 |
20120328053 | Orthogonal Frequency Division Multiplexed (OFDM) Demodulator Imbalance Estimation - Techniques are provided for generating an estimate of the phase and magnitude imbalance of a receiver in a communication device. For each of a plurality of symbols in a signal received by the communication device, a plurality of tones that make up the symbol are obtained. For each of the plurality of symbols, each tone is multiplied by its respective mirror tone to produce a plurality of mirror tone multiplication results, and the plurality of the mirror tone multiplication results are summed over tones to produce a sum of multiplication results for each symbol. The total power of all tones for each symbol is obtained to produce a tone power quantity for each symbol. The estimate of the phase and magnitude imbalance in the received signal is generated based on the sum of the multiplication results for each of the plurality of symbols and the tone power quantity for each of the plurality of symbols. | 12-27-2012 |
20130064161 | Group Addressing for Multicast Transmissions for Power Savings at Physical Layer - Techniques are provided to enable group addressing for multicast transmissions in a frame that is configured to support multi-user transmissions. The frame comprises a header field that is configured to indicate to recipient devices associated with a multi-user transmission interval during which time, frequency and spatial channel resources are allocated to allow for the transmission of a data frame or simultaneous transmission of corresponding ones of a plurality of data frames to respective recipient devices. In the header field, group identification information is wirelessly transmitted that indicates a group of recipient devices which are to receive a transmission during the multi-user transmission interval. Data is wirelessly transmitted for a multicast transmission during the multi-user transmission interval that follows the header field, where the multicast transmission is intended for a group of recipient devices that are members of a multicast group corresponding to group identification information contained in the header field. | 03-14-2013 |
20130128935 | FULL SPATIAL DIMENSION EXTRACTION FOR IMPLICIT BEAMFORMING - Techniques are provided to compute downlink beamforming weights for beamforming multiple spatial streams to a wireless device when that wireless device does not transmit with a maximum number of spatial streams, and thus when the full dimensional knowledge of the wireless channel to that wireless device needs to be implicitly derived. Uplink signals are received at a plurality of antennas of a first wireless device that are transmitted via a plurality of antennas of a second wireless device. The first wireless device derives values at a plurality of subcarriers of the received signals across the plurality of antennas of the first wireless device. Downlink beamforming weights are computed from values of consecutive subcarriers across the plurality of antennas of the first wireless device. The first wireless device applies the downlink beamforming weights at respective subcarriers to a number of spatial streams to be transmitted to the second wireless device. | 05-23-2013 |
20130286863 | Uplink Signal Bandwidth Characterization from Channel State Information - Techniques are provided to determine whether or not incident power at a wireless communication device in at least two frequency channels is from the same device. Incident power in frequency channels allocated to a basic service set in a wireless network is received at a plurality of antennas of the wireless communication device. Channel state information is computed for at least two frequency channels allocated to the basic service set. One or more metrics are generated based on the channel state information in the two frequency channels. The one or more metrics are evaluated to characterize an uplink signal bandwidth associated with the two channels to determine whether or not the incident power in the two channels is from the same device. | 10-31-2013 |
20130287131 | Two Stage Precoding for Multi-User MIMO Systems - Techniques are provided for generating a precoding matrix for a multi-user multiple-input multiple-output wireless communication system. A first wireless communication device is provided that has a plurality of antennas from which multiple spatial streams are to be simultaneously transmitted to a plurality of second wireless communication devices. A channel matrix is computed between the antennas of the first device and the antennas of each of the second wireless communication devices to produce a plurality of client-specific channel matrices. A singular value decomposition is computed of each client-specific channel matrices. A number of strongest singular values and their corresponding singular vectors are stored from the singular decomposition of each of the client-specific channel matrices. From each client-specific channel matrix, a principal component-like single-client channel matrix is computed. The principal component-like single-client channel matrices are combined to form a principal component-like multi-user channel matrix, from which the precoding matrix is computed. | 10-31-2013 |
20140050156 | Dynamic Channel Assignment for WLAN Deployments with IEEE 802.11ac Access Points - Techniques are provided for selecting channels for use by access points operating in a wireless local area network. Metrics are computed for at least one set of radio frequency (RF) channels, wherein the set of RF channels comprises at least two RF channels in a frequency band that are available for use by a wireless network for a wider bandwidth mode that combines bandwidth of two or more RF channels. Alignment of individual primary and secondary RF channels is determined in the set of RF channels for operation of at least first and second wireless networks. A bias is applied to the metrics for each RF channel that is a member of the set of RF channels for the primary channel depending on alignment of the primary and secondary channels of the respective first and second wireless networks to produce adjusted metrics, based on which RF channels are assigned. | 02-20-2014 |
20140098748 | Dynamic Bandwidth Selection for Wide Bandwidth Wireless Local Area Networks - Dynamic bandwidth selection techniques are provided for a plurality of wireless access point devices that operate in a wireless local area network. Each access point device is capable of serving wireless client devices with a bandwidth from a set of possible bandwidths associated with one or multiple contiguous or non-contiguous radio frequency channels. A bias is generated based on determined type of traffic or client composition for each access point device, the bias favoring a channel assignment that results in a particular bandwidth in the set of bandwidths. The bias is applied to metrics representing severity and degree of interference for each channel to generate adjusted metrics. A bandwidth from the set of possible bandwidths is selected for each access point device based on the adjusted metrics. | 04-10-2014 |
20150016435 | Hybrid Contention Mechanism for WLANs - Techniques are presented herein for providing hybrid contention mechanisms for a wireless medium. A first wireless device (e.g., a wireless access point) that serves a plurality of second wireless devices (e.g., client devices) in a wireless network, groups the plurality of second wireless devices into sets based on commonality of the second wireless devices in terms of one or more of: power requirements and throughput requirements. A time interval on a wireless channel during which the second wireless devices may contend for usage of the wireless medium is partitioned into a plurality of disjoint or overlapping contention periods. Each set of second wireless devices is assigned to a corresponding one of the plurality of contention periods such that only second wireless devices in each set contend for access to the wireless channel during the corresponding contention period assigned to that set. | 01-15-2015 |