Abstract: A method selects antennas in a multiple-input, multiple-output (MIMO) wireless local area network (WLAN) that includes a plurality of stations, and each station includes a set of antennas. Plural consecutive packets, received at a station, include plural consecutive sounding packets. Each sounding packet corresponds to a different subset of the set of antennas, and at least one of the plural consecutive packets includes a high throughput (HT) control field including a signal to initiate antenna selection and a number N indicative of a number of sounding packets which follow the at least one packet including the HT control field and which are to be used for antenna selection. A channel matrix is estimated based on a characteristic of the channel as indicated by the received N sounding packets, and a subset of antennas is selected according to the channel matrix. Station and computer program product embodiments include similar features.

Abstract: A movable portion of an array of antenna elements receives RF signals. A movable ultra-wideband (UWB) transmitter is connected to each antenna element, via a RF to UWB converter. A fixed portion of the antenna array is separated from the movable portion by an air gap. The fixed portion includes one fixed UWB receiver for each movable UWB transmitter. An application system is connected to the fixed UWB receivers. The UWB signals from the movable transmitter are sent across the air gap to the fixed UWB receivers to be processed by the application system as the movable portion rotates.

Abstract: A method determines a duration of a frame in a time-hopping, impulse radio system. Channel state information of a channel between two transceivers is estimated periodically. A signal to noise and interference ratio is also estimated periodically. The frame duration of the frame is then determined according to the channel state information and the signal to noise and interference ratio.

Abstract: A method switches a mobile station (MS) from a current group to a new group in a Worldwide Interoperability for Microwave Access (WiMAX) including a base station (BS). The BS operates in full duplex mode and the MS operates in half-duplex mode, such that the WiMAX network operates in semi-duplex mode. The MS receives from the BS, while the MS is in the current group, a group switching request in a downlink (DL) sub-frame. The MS also receives structural information regarding frames of the new group. The MS switches from the current group to the new group after receiving the structural information.

Abstract: A method transmits a sequence of symbols in a multiple-input multiple-output (MIMO) network including a transmitter having a set of transmit antennas and a receiver having a set of receive antennas. The sequence of symbols is represented by a vector S=[S1 S2 S3 S4]T of individual symbols, where T is a transpose operator. The individual symbols are transmitted as a transmit matrix S = [ S 1 - S 2 * S 1 - S 2 * S 2 S 1 * S 2 S 1 * S 3 - S 4 * - S 3 S 4 * S 4 S 3 * - S 4 - S 3 * ] , where * is a complex conjugate, and wherein each column of the matrix S represents the symbols transmitted at each transmission interval, and subscripts index the set of transmit antennas.

Abstract: A method selects antennas in a wireless network including a base station and one or more transceivers. The base station specifies times, subcarriers and subsets of antennas to use to transmit sounding reference signals (SRS) to the base station. Then, the transceiver transmits the SRS according to the specified times and subcarriers using different subsets of the set antennas. The SRS are received in the base station, and the base station selects one of the different subset of the antennas based on the received SRS, and indicates the selected subset of the antennas to the transceiver.

Abstract: A method selects a route in a wireless cooperative relay network of nodes, the nodes including a source, a set of relays, and a destination. A codeword is encoded as a data stream. The data stream is transmitted from a source to a destination via a set of relays. Mutual information is accumulated at a particular node to decode the data stream and recover the codeword. Then, a route from the source to the destination is selected based on channel state information between the nodes while transmitting and accumulating.

Abstract: A method estimates channels in a wireless cooperative cellular network including a set of base stations, and each base station communicates cooperatively with a set of mobile stations. A first sounding signal including a first midamble is transmitted from a first base station to a first mobile station. A second sounding signal including a second midamble is transmitted simultaneously from a second base station to the first mobile station, wherein the first and second midamble are disjoint in time, and wherein the first and second midambles are used to estimate the channels between the first base station and the first mobile station, and the second base station and the first mobile station, respectively.

Abstract: A base station transmits a set of sounding requests to a set of mobile station (MS) in a cell, using a set of beams, wherein there is one beam for each sounding request. Qualities of sounding signals transmitted by the set of MSs in response to receiving the sounding request are measured, and the set of MSs are grouping into subsets according to the qualities, wherein there is one subset of MSs associated with each beam.

Abstract: An orthogonal frequency division multiple access (OFDMA) network including a base station (BS) associated with a set of mobile stations (MS) in a cell. The set of MS are grouped into sets of active MS, wherein each set of active MS corresponds to a beam formed at the BS. The BS transmits a down link (DL) subframe using analog beam forming (ABF), wherein the DL subframe has one ABF zone for each set of active MS and each corresponding beam.

Abstract: A method and system selects a subset of antennas from a set of antennas to transmit user data in a wireless communication system. The user data is transmitted during a first transmission time intervals (TTI) using a first subset of antennas. Pilot tones are transmitted during a second TTI using a second subset of antennas. Corresponding channel qualities are estimated for the first subset of antennas and the second subset of antennas from the user data and the pilot tones. Then, based on the estimating, a best subset of antenna is selected from the first subset of antennas and the second subset of antennas to transmit the user data during a subsequent TTI.

Abstract: A method determines a delay time between reference and data pulses in a time-hopping impulse radio system. Channel state information of a channel between two transceivers is estimated periodically. The delay time frame between the reference and data pulses is then determined according to the channel state information.

Abstract: A movable portion of an array of antenna elements receives RF signals. A movable ultra-wideband (UWB) transmitter is connected to each antenna element, via a RF to UWB converter. A fixed portion of the antenna array is separated from the movable portion by an air gap. The fixed portion includes one fixed UWB receiver for each movable UWB transmitter. An application system is connected to the fixed UWB receivers. The UWB signals from the movable transmitter are sent across the air gap to the fixed UWB receivers to be processed by the application system as the movable portion rotates.

Abstract: A method transmits a block of symbols in a multiple-input multiple-output (MIMO) network including a transmitter having a set of transmit antennas and a receiver having a set of receive antennas. A block of symbols is coded with a first code to generate a first block, which is transmitted and received. If a decoding of the first block is incorrect, then block of symbols is coded with the first code and then a second code different than the first code to generate a second block. The second block is transmitted, received and combined with the first block to recover the block of symbols.

Abstract: A method communicates symbols in a cell of a multiple-input multiple-output (MIMO) network that includes a set of mobile station and a base station. The symbols are communicated using orthogonal frequency division multiplexing (OFDM) and time division duplex (TDM). A frame for communicating the symbols between the base station and the mobile station is constructed. The frame is partitioned into a downlink subframe and an uplink subframe. The uplink subframe is partitioned into a first zone and a second zone, wherein the first zone uses orthogonal frequency division multiple access (OFDMA) and the second zone uses single carrier frequency division multiple access (SC-FDMA).

Abstract: A method for identifying a leading edge time period of a received radio signal includes identifying a greatest energy time period in a sequence of time periods. The received radio signal has a greatest average energy in the greatest energy time period. The method also includes identifying a least energy time period in the sequence of time periods. The received radio signal has a least average energy in the least energy time period. Further, the method includes setting a threshold energy based on the greatest average energy and the least average energy, determining a number of window time periods based on a characteristic of a radio channel used by the received radio signal, and identifying as a leading edge time period an earliest time period that precedes the greatest energy time period within the number of window time periods. The received radio signal in the leading edge time period has an average energy greater than or equal to the threshold energy.

Abstract: A method, system and network transmit data from a base station, via relay stations, to user stations. Imperfect channel state information (CSI) for downlink channels from the base station and the relay stations to the user stations is acquired. For each candidate transmission strategy of a set of candidate transmission strategies, a corresponding beamforming matrix is determined according the imperfect CSI. For each beamforming matrix, a bound on an expected target benefit function is determined, and a particular one of the bounds is selected. The data are then transmitted from the base station, via the relay stations, to the user stations according to the beamforming matrix associated and the candidate strategy associated with the selected bound.

Abstract: A method and system transmits an input stream of data symbols in a multiple-input/multiple-output wireless communications system that includes M subgroups of transmitting antennas. A stream of data symbols is provided to a combined switch and demultiplexer. The combined switch and demultiplexer selects a subset L of the M subgroups of antennas as active, where L<M. The demultiplexer then splits the data stream into L substreams, which are fed to the L subgroups of antennas. Before transmission, each of the L substreams is adaptively modulated and coded to a maximum data rate while achieving a predetermined performance on an associated channel used to transmit the substream. Space-time transmit diversity encoding is applied to each coded substream to generate multiple output streams, one output stream for each antenna of each of the L subgroups. The selection by the switch is based on channel conditions fed back by a receiver of the output streams.

Abstract: A method is provided for receiving data at a receiver via a communication channel from a transmitter having at least two transmitter antennas, the method including: receiving (S204) a codebook including an assignment of at least two respective codewords to the at least two transmitter antennas, the assignment being based at least in part on a characteristic of the communication channel; detecting a state of the communication channel by which the receiver can communicate with the transmitter; selecting (S206) at least one desired transmitter antenna from the at least two antennas based at least in part on the detected state of the communication channel; transmitting (S208) to the transmitter a codeword corresponding to the at least one desired transmitter antenna; and receiving (S210) data at the receiver transmitted by the transmitter.

Abstract: A method and network communicate packets by assigning, in each one of a set of multiple transmitters, a power level to a packet to be transmitted during a time interval. The power level is selected from a set of power levels available for the set of multiple transmitters. The power levels in the set range from highest to lowest. There is one packet for each transmitter such that there is a set of packets to be transmitted during the time interval. The set of packets is transmitted concurrently during the time interval to enable decoding of at least one of the packets in the set of packets during the time interval.