Patent application number | Description | Published |
20080273617 | STEERING DIVERSITY FOR AN OFDM-BASED MULTI-ANTENNA COMMUNICATION SYSTEM - A transmitting entity uses different steering vectors for different subbands to achieve steering diversity. Each steering vector defines or forms a beam for an associated subband. Any steering vector may be used for steering diversity. The steering vectors may be defined such that the beams vary in a continuous instead of abrupt manner across the subbands. This may be achieved by applying continuously changing phase shifts across the subbands for each transmit antenna. As an example, the phase shifts may change in a linear manner across the subbands for each transmit antenna, and each antenna may be associated with a different phase slope. The application of linearly changing phase shifts to modulation symbols in the frequency domain may be achieved by either delaying or circularly shifting the corresponding time-domain samples. | 11-06-2008 |
20090059855 | DISTRIBUTED HIERARCHICAL SCHEDULING IN AN AD HOC NETWORK - An ad hoc network with distributed hierarchical scheduling is disclosed. In one aspect, stations in a network mesh detect interfering neighbor stations and form interference lists. Stations transmit their interference lists. Scheduling stations schedule allocations for child stations in response to interference lists, received remote allocations, or a combination thereof. Coordination messages are transmitted including frame structure, allocations, and interference lists, among others. In another aspect, an ad hoc mesh network may be organized into a tree topology. In an example wireless backhaul network, this matches traffic flow. Distributed, hierarchical scheduling is provided where parents schedule communication with children while respecting already scheduled transmissions to/from interferers and to/from interferers of their respective children. Procedures to construct interference constraints for distributed, hierarchical scheduling are described, resulting in efficient scheduling and reuse in an ad hoc wireless network, without centralized scheduling. Various other aspects are also disclosed. | 03-05-2009 |
20090124214 | REMOTE FRONT-END FOR A MULTI-ANTENNA STATION - A multi-antenna station has multiple remote front-ends coupled to multiple antennas. Each remote front-end includes a power amplifier (PA), a low noise amplifier (LNA), and first and second coupling units. On the transmit path, a first RF signal is received via a first port, routed by the first coupling unit to the power amplifier, amplified to obtain the desired output power level, and routed by the second coupling unit to a second port for transmission via the antenna. On the receive path, a second RF signal is received via the second port, routed by the second coupling unit to the LNA, amplified to obtain a higher signal level, and routed by the first coupling unit to the first port for transmission to the transceiver. | 05-14-2009 |
20090137221 | INTERFERENCE MANAGEMENT IN A WIRELESS COMMUNICATION SYSTEM USING BEAM AND NULL STEERING - Interference that occurs during wireless communication may be managed through the use of beam and null steering techniques. A method, apparatus and medium of communication determine an interference direction of a non-associated access terminal generating an interfering signal. Transmitted and received signals are then transceived away from the interference direction. | 05-28-2009 |
20090190565 | ACQUISITION OF TIMING INFORMATION IN WIRELESS COMMUNICATION SYSTEMS - 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. | 07-30-2009 |
20090290655 | TRANSMISSION MODE AND RATE SELECTION FOR A WIRELESS COMMUNICATION SYSTEM - To select a transmission mode to use for a data transmission via a MIMO channel from station A to station B, station A obtains channel information used for spatial processing and determines the age of this information. Station A selects one of multiple transmission modes based on the age of the channel information and possibly other information (e.g., the fading characteristic of the MIMO channel). To select rate(s) to use for the data transmission, station A obtains channel state information (CSI) indicative of the received signal quality for the MIMO channel, e.g., received SNRs or “initial” rates. Station A determines the age of the CSI and selects one or more “final” rates based on the CSI, the age of the CSI, the selected transmission mode, and possibly other information. Station A processes data in accordance with the selected transmission mode and final rate(s) and transmits the processed data to station B. | 11-26-2009 |
20090290657 | Continuous Beamforming for a MIMO-OFDM System - A transmitting entity performs spatial processing on data symbols for each subband with an eigenmode matrix, a steering matrix, or an identity matrix to obtain spatially processed symbols for the subband. The data symbols may be sent on orthogonal spatial channels with the eigenmode matrix, on different spatial channels with the steering matrix, or from different transmit antennas with the identity matrix. The transmitting entity further performs beamforming on the spatially processed symbols, in the frequency domain or time domain, prior to transmission from the multiple transmit antennas. A receiving entity performs the complementary processing to recover the data symbols sent by the transmitting entity. The receiving entity may derive a spatial filter matrix for each subband based on a MIMO channel response matrix for that subband and perform receiver spatial processing for the subband with the spatial filter matrix. | 11-26-2009 |
20090323646 | METHOD AND APPARATUS FOR WIRLESS LAN (WLAN) DATA MULTIPLEXING - Embodiments addressing MAC processing for efficient use of high throughput systems are disclosed. Data associated with at least one MAC ID can be aggregated into a single byte stream. The single byte stream can be formatted into MAC PDUs and then muxed. The muxed MAC PDUs can then be transmitted on a single MAC frame. Muxing of the MAC PDUs can be based on the priority of the MAC PDUs or other criteria. A MAC header can comprise information about the muxed PDUs, such as a pointer, that identifies the location of the MAC PDUs within the MAC frame. A MAC frame can contain partial MAC PDUs. The transmitted muxed MAC PDUs can be retransmitted, and an acknowledgment or feedback scheme may be used to help manage the transmission of the protocol data units. | 12-31-2009 |
20100074301 | UNIFIED MIMO TRANSMISSION AND RECEPTION - 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. | 03-25-2010 |
20100150038 | APPARATUS AND METHOD FOR WIRELESS COMMUNICATION VIA AT LEAST ONE OF DIRECTIONAL AND OMNI-DIRECTION ANTENNAS - Techniques for using at least one of omni-directional and directional antennas for communication are described. A station may be equipped antenna elements selectable for use as an omni-directional antenna or one or more directional antennas. The station may select the omni-directional antenna or a directional antenna for use for communication based on various factors such as, e.g., whether the location or direction of a target station for communication is known, whether control frames or data frames are being exchanged, etc. | 06-17-2010 |
20100150077 | APPARATUS AND METHOD FOR WIRELESS COMMUNICATION VIA AT LEAST ONE OF DIRECTIONAL AND OMNI-DIRECTION ANTENNAS - Techniques for using at least one of omni-directional and directional antennas for communication are described. A station may be equipped antenna elements selectable for use as an omni-directional antenna or one or more directional antennas. The station may select the omni-directional antenna or a directional antenna for use for communication based on various factors such as, e.g., whether the location or direction of a target station for communication is known, whether control frames or data frames are being exchanged, etc. | 06-17-2010 |
20110142097 | DATA TRANSMISSION WITH SPATIAL SPREADING IN A MIMO COMMUNICATION SYSTEM - 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. | 06-16-2011 |
20110286556 | ACQUISITION OF TIMING INFORMATION IN WIRELESS COMMUNICATION SYSTEMS - 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. | 11-24-2011 |
20110299417 | MULTIPLE FREQUENCY BAND OPERATION IN WIRELESS NETWORKS - 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 ( | 12-08-2011 |
20120114019 | RANGE EXTENSION TECHNIQUES FOR A WIRELESS LOCAL AREA NETWORK - 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. Other aspects, features, and embodiments are also claimed and described. | 05-10-2012 |
20120127978 | RANGE EXTENSION TECHNIQUES FOR A WIRELESS LOCAL AREA NETWORK - 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. Other aspects, embodiments, and features are also claimed and described. | 05-24-2012 |
20120250788 | SPATIAL SPREADING IN A MULTI-ANTENNA COMMUNICATION SYSTEM - Spatial spreading is performed in a multi-antenna system to randomize an “effective” channel observed by a receiving entity for each transmitted data symbol block. For a MIMO system, at a transmitting entity, data is processed (e.g., encoded, interleaved, and modulated) to obtain N | 10-04-2012 |
20130157578 | APPARATUS AND METHOD FOR WIRELESS COMMUNICATION VIA AT LEAST ONE OF DIRECTIONAL AND OMNI-DIRECTION ANTENNAS - Techniques for using at least one of omni-directional and directional antennas for communication are described. A station may be equipped antenna elements selectable for use as an omni-directional antenna or one or more directional antennas. The station may select the omni-directional antenna or a directional antenna for use for communication based on various factors such as, e.g., whether the location or direction of a target station for communication is known, whether control frames or data frames are being exchanged, etc. | 06-20-2013 |
20130188677 | REDUCED COMPLEXITY BEAM-STEERED MIMO OFDM SYSTEM - Techniques for transmitting data using channel information for a subset of all subcarriers used for data transmission are described. A transmitter station receives channel information for at least one subcarrier that is a subset of multiple subcarriers used for data transmission. The channel information may include at least one transmit steering matrix, at least one set of eigenvectors, at least one channel response matrix, at least one channel covariance matrix, an unsteered pilot, or a steered pilot for the at least one subcarrier. The transmitter station obtains at least one transmit steering matrix for the at least one subcarrier from the channel information and determines a transmit steering matrix for each of the multiple subcarriers. The transmitter station performs transmit steering or beam-steering for each of the multiple subcarriers with the transmit steering matrix for that subcarrier. | 07-25-2013 |
20130230038 | HIGH SPEED MEDIA ACCESS CONTROL AND DIRECT LINK PROTOCOL - Techniques for MAC processing for efficient use of high throughput systems that may be backward compatible with various types of legacy systems are disclosed. In one aspect, a data frame is formed comprising a common portion for transmission in a format receivable by various stations, such as access points and remote stations. The data frame also comprises a dedicated portion, formatted for transmission to a specified remote station. In another aspect, the common portion is unsteered, and the dedicated portion is steered. In another aspect, an access point schedules an allocation in response to a data indication included in a common portion of a data frame transmitted from one remote station to another. In another aspect, a first station transmits a reference to a second station, which measures the reference and generates feedback therefrom. | 09-05-2013 |
20130287043 | HIGH SPEED MEDIA ACCESS CONTROL - Embodiments disclosed herein for MAC processing for efficient use of high throughput systems and that may be backward compatible with various types of legacy systems. In one aspect, a data transmission structure comprises a consolidated poll and one or more frames transmitted in accordance with the consolidated poll. In another aspect, a Time Division Duplexing (TDD) data transmission structure comprises a pilot, a consolidated poll, and zero or more access point to remote station frames in accordance with the consolidated poll. In one aspect, frames are transmitted sequentially with no or substantially reduced interframe spacing. In another aspect, a guard interframe spacing may be introduced between frames transmitted from different sources, or with substantially different power levels. In another aspect, a single preamble is transmitted in association with one or more frames. In another aspect, a block acknowledgement is transmitted subsequent to the transmission of one or more sequential frames. | 10-31-2013 |
20130322562 | METHOD AND APPARATUS FOR ANTENNA TUNING AND TRANSMIT PATH SELECTION - Certain aspects of the present disclosure propose a method and an apparatus for antenna tuning and transmit path selection in an RF system. A method may include antenna diversity path selection by (optionally) diagnosing damaged antennas, tuning antennas, and selecting an antenna with better performance. Embodiments can be used in wireless radio-frequency (RF) front-ends. Other aspects, embodiments, and features are also claimed and described. | 12-05-2013 |
20140348258 | MIMO WLAN SYSTEM - A multiple-access MIMO WLAN system that employs MIMO, OFDM, and TDD. The system (1) uses a channel structure with a number of configurable transport channels, (2) supports multiple rates and transmission modes, which are configurable based on channel conditions and user terminal capabilities, (3) employs a pilot structure with several types of pilot (e.g., beacon, MIMO, steered reference, and carrier pilots) for different functions, (4) implements rate, timing, and power control loops for proper system operation, and (5) employs random access for system access by the user terminals, fast acknowledgment, and quick resource assignments. Calibration may be performed to account for differences in the frequency responses of transmit/receive chains at the access point and user terminals. The spatial processing may then be simplified by taking advantage of the reciprocal nature of the downlink and uplink and the calibration. | 11-27-2014 |