Abstract: A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective transmission systems that adapt or can be adapted to the radio environment.

Abstract: Method and apparatus to manage retransmissions in a wireless network are described.

Abstract: A multicarrier transmitter may transmit cyclically delayed linear combinations of two or more data streams with three or more antennas. In some embodiments, the multicarrier transmitter may transmit cyclically delayed linear combinations of three data streams with four antennas.

Abstract: A receiver may receive ultra-wideband, spread-spectrum differential signals. In some embodiments, the receiver may use a variable bandwidth low pass filter. Lowering or raising the bandwidth of the low pass filter may improve performance in particular wideband signal situations.

Abstract: The present invention describes a network communication system which includes a first slave transceiver configured to communicate a plurality of TDMA data packets at different data rates to a second slave transceiver. The second slave transceiver is also configured to communicate a plurality of TDMA data packets at different data rates to the first slave transceiver. A master transceiver manages data communications between the first slave transceiver and the second slave transceiver. Each transceiver includes a data modulation unit, a transmitter, an antenna, and a receiver. The data modulation unit is configured to generate a plurality of signals having variable pulse repetition frequencies and different modulation techniques. The transmitter is coupled to the data modulation unit and the transmitter is configured to generate a pulse stream according to the data modulation unit.

Abstract: An ultrawideband radio frequency pulse is generated by shaping a carrier signal having a selected frequency with a window function. The shaped carrier is gated to produce the ultrawideband pulse. In further embodiments, the window function comprises a sinusoidal function, and the ultrawideband pulse is formed via a mixer and a CMOS radio frequency switch.

Abstract: The present invention describes a network communication system which includes a first slave transceiver configured to communicate a plurality of TDMA data packets at different data rates to a second slave transceiver. The second slave transceiver is also configured to communicate a plurality of TDMA data packets at different data rates to the first slave transceiver. A master transceiver manages data communications between the first slave transceiver and the second slave transceiver. Each transceiver includes a data modulation unit, a transmitter, an antenna, and a receiver. The transmitter is coupled to the data modulation unit and the transmitter is configured to generate a pulse stream according to the data modulation unit. The receiver is configured to detect and demodulate said ultra wide band base band signals operating at variable pulse repetition frequencies and having different modulation methods.

Abstract: A base station may organize poll groups into groups having similar predicted durations of subsequent responses. In one embodiment predicted durations may be provided by the devices that are to be polled. In another embodiment the predicted durations may be based on past responses from the devices that are to be polled.

Abstract: In a spatial division multiple access system that employs acknowledgements to variable length transmissions within a timeout period, a station that has completed its transmission may delay beginning the timeout period until it determines that other stations on the same channel have completed their transmissions.

Abstract: During a training phase in a network using spatial division multiple access (SDMA) techniques, frame types that trigger network allocation vectors may be used in the training phase to prevent unwanted devices from transmitting during the training phase.

Abstract: Methods and structures are disclosed for use in implementing downlink spatial division multiple access (SDMA) in a wireless network.

Abstract: In an orthogonal frequency division multiplexed (OFDM) system, a transmitter and/or receiver communicate separate data streams on non-orthogonal spatial channels. Each spatial channel may use the same set of OFDM subcarriers and may take advantage of the multipath characteristics of the spatial channel allowing the communication of additional data without an increase in frequency bandwidth. Space-frequency subcarrier modulation assignments may be dynamically assigned on a per subcarrier basis as well as a per spatial channel basis to help maximize the data-carrying capacity of the channel. In some embodiments, each of the spatial channels may be associated with one of a plurality of spatially diverse antennas. In other embodiments, beamforming may be performed to allow the transmission and/or reception of signals within the spatial channels.

Abstract: In a base station using spatial division multiple access communications, different length transmissions directed from a base station to different multiple mobile devices substantially simultaneously may have their start times adjusted so that the transmissions end at approximately the same time. The mobile devices may then respond during a response period with acknowledgments at approximately the same time. Thus all the acknowledgments may be received within the same time period from the end of the transmissions, reducing the likelihood of missed acknowledgments in responses to the shorter transmissions.

Abstract: According to some embodiments, a technique is provided that coordinates transmission of frames to reduce collisions. Frames are coordinated according to, for example, operation type, frame length, and solicited response. A base station gains access to a wireless medium and transmits multiple coordinated frames to multiple communication units. The transmissions to the multiple communication units may be substantially simultaneous in that at least a portion of the different frames are transmitted at the same time. The different frames may be substantially back-end aligned where the maximum difference between the termination time instances of the frame transmissions is controlled to reduce collisions.

Abstract: When initiating SDMA training sequences, a base station may poll multiple mobile devices with the same multicast training poll, and the polled mobile stations may respond separately at different times based on an assigned delay period for each mobile station.

Abstract: An access point in a wireless network communicates with multiple mobile stations simultaneously using spatial-division multiple access.

Abstract: In Spatial Division Multiple Access (SDMA) communications, mobile devices that are transmitting to a base station substantially simultaneously during a predetermined communications phase may wait until after an end of the predetermined communications phase to receive acknowledgments to their transmissions, so that a mobile device making a relatively short transmission does not experience an acknowledgment timeout while another mobile device is still completing a relatively long transmission. In some embodiments, the mobile devices may transmit a non-immediate block acknowledgment request during the communications phase.

Abstract: A network comprising a base station and multiple mobile devices may use a training phase for the base station to develop parameters that enable spatial division multiple access (SDMA) techniques to be used for communications with the mobile devices, and to subsequently use those parameters in a data phase, thus permitting substantially simultaneous transmissions to, and substantially simultaneous receptions from, the multiple mobile devices on the same frequency.

Abstract: A switched antenna system selects an antenna based on symbol error rate.

Abstract: A compensating correction value for adjusting analog signals received from multiple antenna elements takes into account the effects of colored noise, co-channel interference, and inter-sample interference. The method of generating the compensating correction value for analog combining architectures considers the total channel impulse response over a block of time.