Cochannel signal processing system

A method for processing cochannel signals received at a sensor array, the method comprising the steps of:

• conditioning a set of signals received at a sensor array;
• generating an estimated generalized steering vector (EGSV) that results in optimization of a utility function that depends on fourth or higher even-order statistical cumulants derived from the received signals, the EGSV being indicative of a combination of signals received at the sensors from a signal source;
• and
• performing supplemental computation to derive at least one output quantity of interest from the conditioned receiver signals and the EGSV.

A method for recovery and separation of multiple cochannel signals of any modulation or type received at an array of sensors, the method comprising the steps of:

• receiving a plurality of cochannel signals from separate signal sources at an array of sensors;
• preprocessing the received signals to provide preprocessed signals;
• coupling the preprocessed signals to a plurality of signal extraction ports, each of which is in one of two states referred to as an active state and an inactive state;
• in association with each signal extraction port in the active state, generating an estimated steering vector and a recovered signal corresponding to one of the signal sources, without regard for manifold data of the sensor array;
• orthogonalizing the estimated steering vectors to ensure that each signal extraction port generates a recovered signal for a separate signal source;
• and
• controlling the steps of orthogonalizing and generating recovered signals to ensure an orderly association of signal sources with signal extraction ports.

A receiver/transmitter system for receiving cochannel signals simultaneously from multiple remote units and transmitting cochannel signals to the remote units simultaneously, the system comprising:

• a signal receiving system, including means for generating from signals received at a receive sensor array a set of conditioned receiver signals;
• a plurality of estimated generalized steering vector (EGSV) generators, for computing for each transmitting remote unit an EGSV that results in optimization of a utility function that depends on fourth or higher even-order statistical cumulants derived from the received signals, each EGSV being indicative of a combination of signals received at the sensors from the remote unit;
• a recovery beamformer weight vector computation module, for generating from all of the EGSVs a plurality of receive beamforming weight vectors;
• a plurality of recovery beamformers, each coupled to receive one of the receive beamforming weight vectors and the conditioned receiver signals, for generating a plurality of recovered signals;
• a transmit weight vector computation module, for generating transmit beamforming weight vectors from the receive beamforming weight vectors generated by the recovery beamformer weight vector computation module;
• and
• a plurality of linear combiners, for combining each information signal to be transmitted with an associated transmit weight vector, to obtain a weighted transmit beam for each of the information signals to be transmitted, and then combining corresponding components of the weighted transmit beams, for coupling to a transmit array.

A method for using a receiver/transmitter system for receiving cochannel signals simultaneously from multiple remote units and transmitting cochannel signals to the remote units simultaneously, the method comprising the steps of:

• receiving signals from a receive sensor array;
• generating from the received signals a set of conditioned receiver signals;
• computing for each transmitting remote unit an estimated generalized steering vector that results in optimization of a utility function that depends on fourth or higher even-order statistical cumulants derived from the received signals, the estimated generalized steering vector being indicative of a combination of signals received at the sensors from the remote unit;
• generating from all of the generalized steering vectors a plurality of receive beamforming weight vectors;
• generating from the receive beamforming weight vectors and the conditioned receiver signals a plurality of recovered signals corresponding to the signals received from the respective remote units;
• generating transmit beamforming weight vectors from the receive beamforming weight vectors;
• combining each information signal to be transmitted with an associated transmit weight vector, to obtain a weighted transmit beam for each of the information signals to be transmitted;
• and
• combining corresponding components of the weighted transmit beams, for coupling to a transmit array.

A two-way communication system using cochannel signals and diversity path multiple access (DPMA) for transmission in both directions, the system comprising:

• at least one receiver/transmitter base station for communicating with a plurality of mobile devices having omnidirectional antennas for transmitting uplink signals at an assigned frequency and receiving downlink signals at another assigned frequency, wherein the receiver/transmitter base station includes
• a receive antenna array,
• a plurality of estimated generalized steering vector (EGSV) generators, for computing for each mobile device an EGSV that results in optimization of a utility function that depends on fourth or higher even-order statistical cumulants derived from the received signals, the EGSV being indicative of a combination of uplink signals received at the receive antenna array from the mobile device over possible multiple paths,
• receiver processing means for generating from the EGSVs a recovered signal corresponding to each uplink signal from a mobile device, and a receive beamforming weight vector corresponding to the uplink signal,
• a transmitter, including means for generating from each receive beamforming weight vector a corresponding transmit beamforming weight vector, and a modulator for modulating a downlink transmission signal with a desired information signal,
• a transmit antenna array coupled to the transmitter and having a similar geometrical shape as the receive antenna array, wherein downlink transmission signals intended for a particular mobile device are propagated along generally the same multiple paths as the received uplink signals from the same mobile device;
• wherein coherent uplink signals received over multiple paths from the same mobile device are automatically combined, providing a gain enhancement effect that allows weaker transmissions to be detected, and downlink signals transmitted over the same multiple paths also benefit from the gain enhancement effect and provide a stronger downlink signal to the mobile device.

A method of radio direction finding (DF) using a subarray of calibrated antennas, the method comprising the steps of:

• receiving signals from multiple sources, at an antenna array of which only a small number of antenna elements are calibrated;
• separating the signals using a cumulant recovery (CURE) system to generate the separated signals and estimates of their generalized steering vectors;
• and
• processing the estimated generalized steering vectors and signals from the calibrated antenna elements, to obtain accurate signal directions for the multiple sources.