Abstract: A method for selects antennas in a spatial division multiple access (SDMA) wireless network that includes a base station and a set of mobile stations, in which the set of mobile stations includes one or more designated mobile stations, and in which each designated mobile station has a set of multiple antennas. Channel state information (CSI) is acquired for a channel between each mobile station in the set of mobile stations and the base station, and in which the CSI for each designated mobile station is acquired for different subsets of the set of multiple antennas at each designated mobile station. For each designated mobile station, a globally optimal subset of the set of antennas is selected based on the CSI acquired from all the mobile stations.

Abstract: The embodiments of the invention provide an adaptive method for base station cooperation in a wireless network. In a multi-user communications network that includes base stations, and in which each base station is associated with a cell, and in which each cell includes one or more mobile stations, each base station determines pre-coding matrices for full-cooperation, semi-cooperation and non-cooperation. Each base stations also determines a sum rate SRfull for full-cooperation, a sum rate SRsemi semi-cooperation, and a sum rate SRnon for non-cooperation. Then, each base station selects the pre-coding for full-cooperation, the pre-coding matrices for semi cooperation, or the pre-coding matrices for non cooperation. Each base station transmits signals according to the selected per-coding matrices.

Abstract: A method transmits and receives signals in a cooperative, multi-user, multi-input, multi-output network. The network includes base stations (BSs) and mobile stations (MSs). Each BS has at least two antennas, and each MS has at least one antenna. At a first base station and a second base station using linear pre-coding matrices, a plurality of data streams are jointly pre-coded to produce first signals and second signals. The first signals are transmitted synchronously from the first BS and the second BS to a first MS, and the second signals are transmitted synchronously from the first BS and the second BS to a second MS, and in the first signal and the second signal are asynchronous with respect each other.

Abstract: A method and apparatus modulate a polarity of a burst of pulses of the impulse radio signal using a first pseudo noise sequence generated by a shift register and a position of the burst of pulses using a second pseudo noise sequence generated by the shift register.

Abstract: A computer implemented method selects antennas in a multiple-input, multiple-output wireless local area network that includes multiple stations, and each station includes a set of antennas. Multiple consecutively transmitted sounding packets are received in a station. Each sounding packet corresponds to a different subset of the set of antennas. A channel matrix is estimated from the multiple consecutively transmitted sounding packets. A frame including a high throughput (HT) control field is sent to initiate a selecting of antennas, and a subset of antennas is selected according to the channel matrix.

Abstract: A method and system (500) estimates a time of arrival of a signal received via a wireless communications channel. The energy in the received signal is conditioned at multiple different time scales to produce a conditioned signal (700). Then, a leading edge is detected in the conditioned signal (550). The leading edge corresponds to the time of arrival of the received signal (551).

Abstract: A system incorporates time-hopped and transmitted-reference transceivers in the same wireless network. A transmitter modulates a sequence of bits in a wireless communications network by generating a reference waveform and a data waveform of a waveform pair for each current bit. The phase of the reference waveform depends on a previous modulated bit, and a difference in phase between the reference waveform and the data waveform pair depend on the current bit.

Abstract: A method transmits training frames in a MIMO system. A long sequence of training frames is transmitted from a station B to a station A via a channel of the MIMO system, in which the station A includes NA antennas and NA—SS RF chains and the station B includes NB antennas and NB—SS RF chains, and a number of frames in the long sequence of training frames is at least equal to where is a lower bound operator. A short sequence of training frames is transmitted from the station A to the station B via the channel in response to receiving the long sequence of training frames.

Abstract: The invention describes a method for transmitting a packet in a wireless network of nodes. At a beginning of a scheduled time slot a metric in the node is set, in which the metric indicates a need to transmit a packet to a receiver in the wireless network. The metric is mapped to a received power level and the packet is transmitted at a transmit power level so that the received power level is achieved at the receiver.

Abstract: A method selects antennas in an OFDMA wireless network including a base station and a mobile station. The mobile station measures a channel state of a downlink in a downlink subframe using different subsets of available antennas, and selects a subset of receive antennas for downlink reception based on the channel states between the base station and the different subsets of antennas at the mobile station. The base station measures the channel state in an uplink using an uplink subframe received in the base station from the mobile station, and selects a subset of transmit antennas for mobile station's uplink transmission based on the channel states between the base station and different subset of antennas at the mobile station.

Abstract: A method selects antennas in an OFDMA network. A channel state of a downlink is measured using a downlink subframe received in a mobile station from a base station. A channel state of an uplink is measured using an uplink subframe received in the base station from the mobile station. Next, the method compares the channel states to determine whether the downlink and the uplink are reciprocal or not. The mobile station can perform receive antenna selection based on the quality of the downlink channel state. The mobile station can also perform transmit antenna selection when instructed by the base station.

Abstract: A method generates signals in a transmitter of a multiple-input, multiple-output wireless communications system. The transmitter includes Nt transmit antennas. A transmit covariance matrix Rt determined using statistical state information of a channel. The transmit covariance Rt matrix is decomposed using transmit eigenvalues ?t to obtain a transmit eigenspace Ut according to Rt=Ut?tU†t, where † is a Hermitian transpose. A pilot eigenspace Up is set equal to the transmit eigenspace Ut. A NtxTp block of pilot symbols Xp is generated from the pilot eigenspace Up and pilot eigenvalue ?p according to Xp=Up?p1/2. A data eigenspace Ud is set equal to the transmit eigenspace Ut. In addition, a Nt×Nt data covariance matrix Qd is generated according to Ud?dU†d, where ?d are data eigenvalues. A NtxTd block of data symbols is generated, such that an average covariance of each of the columns in the block of data symbols Xd equals the data covariance matrix Qd.

Abstract: A method estimates a time of arrival of a signal received in a wireless communication system. An energy in a frame of a received signal is measured to determine a block in the frame, the block representing a coarse time of arrival of the received signal. Multiple time-delayed versions of a template signal are combined with the block of the received signal to select a particular template signal. The particular template signal identifies a particular chip representing a fine time of arrival of the received signal.

Abstract: A method, apparatus, and system for modulating and demodulating signals compatible with multiple receiver types and designed for improved receiver performance. The invention includes the use of hybrid impulse radio (H-IR) ultra-wideband (UWB) with forward error correction coding, recursive modulation and other techniques designed to enable one transmitter to transmit a waveform capable of being demodulated concurrently by a coherent receiver, a differentially coherent receiver, and/or a non-coherent receiver.

Abstract: A computer implemented method selects antennas in a multiple-input, multiple-output wireless local area network that includes multiple stations, and each station includes a set of antennas. Multiple consecutively transmitted sounding packets are received in a station. Each sounding packet corresponds to a different subset of the set of antennas. A channel matrix is estimated from the multiple consecutively transmitted sounding packets, and a subset of antennas is selected according to the channel matrix.

Abstract: A transmitting station in a radio network includes at least one radio frequency (RF) chain, a packet generator configured to generate a sounding packet including a number of training frames and a signaling frame, and at least one antenna element coupled to the at least one RF chain and configured to broadcast a transmit signal including the sounding packet. The packet generator produces in the sounding packet the number of training frames and the content of the signaling frame based at least in part on the number of antenna elements and the number RF chains.

Abstract: In a wireless network using cooperative relaying, a set of messages are broadcast from a base station to a set of relay stations during a first phase of a scheduling interval. During a second phase of the scheduling interval, the set of messages from the set of relay stations are broadcasting cooperatively to a set of mobile stations, while broadcasting. While broadcasting, a time and a rate and a size of each message is optimized during the first phase, and a rate of each message is optimized during the second phase.

Abstract: A method determines a duration of a frame in an impulse radio system for radio ranging. 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 system incorporates time-hopped impulse radio (TH-IR) and transmitted-reference impulse radio (TR-IR) transceivers in the same wireless network. A transmitter modulates a sequence of bits in a wireless communications network by generating a reference waveform and a data waveform of a waveform pair for each current bit. The phase of the reference waveform depends on a previous modulated bit, and a difference in phase between the reference waveform and the data waveform pair depend on the current bit. A symbol period for the current bit is partitioned into multiple time intervals, and the reference waveform and the data waveform are encoded in a selected one of the time intervals that depends on the current bit.

Abstract: A route is selected in a wireless cooperative relay network of nodes. A decoding order is initialized. A set of resources is minimized subject to constraints. The resources are allocated to the nodes in the decoding order. The decoding order is changed iteratively to further minimize the allocated resources, until a minimum is reached. A code word is transmitted when the allocated resources are at the minimum, which can either be determined globally or locally at each node. The method can operate in a centralized or distributed manner.