Abstract: There is provided a method of parameter estimation in a multi-channel signal environment system wherein a plurality of receiving antennas receives signals or waves from one or more targets due to one or more transmitters that transmit a predetermined signal that is reflected back from the targets or receives signals that are directly transmitted from one or more external transmitters to the receiving antennas and then processed over multiple frequencies or channels by a digital receiver connected to one or more processors.

Abstract: There is provided a method of parameter estimation in a multi-channel signal environment where a plurality of receive antennas receive signals from one or more transmitters that transmit a signal or wave that is reflected from one or more targets, or receive antennas that receive directly from the transmitters, whose received signals are processed over multiple frequencies or channels by a digital receiver.

Abstract: There is provided a method of parameter estimation in a multi-channel signal environment system wherein a plurality of receiving antennas receives signals or waves from one or more targets due to one or more transmitters that transmit a predetermined signal that is reflected back from the targets or receives signals that are directly transmitted from one or more external transmitters to the receiving antennas and then processed over multiple frequencies or channels by a digital receiver connected to one or more processors.

Abstract: The system and method of calibrating a receiver array using a quaternionic scattering model. The calibration method is model based, quick, and suitable for sparse sampling of the array. The calibration scheme can be cheaply and rapidly deployed, either from operational test data or from rapid ground calibration experiments. The model allows for closed loop calibration repair during actual geolocation or line of bearing collects.

Abstract: A method and system of reliably detecting a reactive jamming attack and estimating the jammer's listening interval for exploitation by a communication system comprises channelizing one or more signals of interest (SOI), channelizing one or more signals of unknown origin (SUO), identifying frequency support patterns for the SOI and SUO using Bayes thresholds, comparing SOI and SUO detection map histories, and determining a percent match, where a match percentage above a specified minimum indicates a reactive attack. Edge detection can be used to enhance jammer support. Embodiments further detect reactive jammer adaptation to changes in the SOI's frequency support. Embodiments include detectors that are insensitive to jammer modulation and/or signal type. A jammer reaction delay and/or size and periodicity of receive window can be detected. Embodiments determine if a jammer is copying and retransmitting the SOI's waveform(s), and/or if the jammer is anticipatory.

Abstract: There is provided a method of parameter estimation in a multi-channel signal environment where a plurality of receive antennas receive signals from one or more transmitters that transmit a signal or wave that is reflected from one or more targets, or receive antennas that receive directly from the transmitters, whose received signals are processed over multiple frequencies or channels by a digital receiver.

Abstract: The system and method of calibrating a receiver array using a quaternionic scattering model. The calibration method is model based, quick, and suitable for sparse sampling of the array. The calibration scheme can be cheaply and rapidly deployed, either from operational test data or from rapid ground calibration experiments. The model allows for closed loop calibration repair during actual geolocation or line of bearing collects.

Abstract: Methods and systems are described for transmitting data using various selected resources. For example, first one or more resources may be selected based at least in part on feedback from a first network node. A second network node may cause first data to be transmitted using the selected one or more resources. The second network node may also cause second data to be transmitted using second one or more resources. The resources may comprise, for example, tones, time slots, time-frequency channels, time resources, and/or frequency resources.

Abstract: Methods and systems are described in which a node may cause a plurality of orthogonal frequency division multiplexing (OFDM) symbols to be transmitted. The OFDM symbols may comprise at least a portion of a pilot and/or user data.

Abstract: The system and method of copy aided geolocation in a cochannel environment. The plurality of emitter signals are detected using a multichannel antenna array, separated into subbands based on frequency ranges using a channelizer, and are further processed using copy weights, property restoral algorithms, and maximum likelihood calculations. The multichannel antenna array may be mounted to a mobile platform and the calculations may assume that the signal of interest is non-Gaussian, but the remainder of emitter signals is combined into another signal that is assumed to be Gaussian. The method and system provides geolocation results that adhere to the Cramer-Rao bound.

Abstract: Methods and systems are described in which a node may cause a plurality of orthogonal frequency division multiplexing (OFDM) symbols to be transmitted. The OFDM symbols may comprise at least a portion of a pilot and/or user data.

Abstract: Methods and systems that enhance interference cancellation in communication channels are described. Specialized time domain training sequences and simple cross correlation are used to obtain a channel estimate for use in stacked carrier beamforming and OFDM based spatial beamforming. In certain embodiments, a time domain preamble sequence is provided as an alternative to the conventional frequency domain preamble sequence. The use of a time domain preamble can increase channel estimation performance, facilitating cancellation of co-channel interference. Embodiments include generating a training sequence preamble in the time domain, computing a frequency domain response of the channel using an estimate of its time domain impulse response, and using the frequency domain response of the channel to calculate channel estimation from a cross correlation of data received from the channel against the training sequence.

Abstract: Methods and systems are described for causing orthogonal frequency division multiplexing (OFDM) transmission of various portions of data via various nodes. For example, a first portion of the data may be transmitted, via a first node and using OFDM, to at least a second node. It may be determined that a second portion of the data is to be routed via a different node (such as a third node) for transmission. The second portion of the data may be transmitted, via the third node and using OFDM, to at least the second node.

Abstract: Methods and systems are described for causing orthogonal frequency division multiplexing (OFDM) transmission of various portions of data via various nodes. For example, a first portion of the data may be transmitted, via a first node and using OFDM, to at least a second node. It may be determined that a second portion of the data is to be routed via a different node (such as a third node) for transmission. The second portion of the data may be transmitted, via the third node and using OFDM, to at least the second node.

Abstract: Methods and systems are described for transmitting data to a node using a plurality of radio frequency channels. The data may be allocated, based on feedback from the node, into various portions amongst multiple radio frequency channels and/or amongst tones associated with the radio frequency channels. The data portions may be transmitted to the node, using frequency diversity, via respective radio frequency channels as at least part of respective orthogonal frequency division multiplexing (OFDM) transmissions, which may be at least partially concurrent transmissions.

Abstract: An exemplary wireless communication network that includes a base that communicates with remote units located in a cell of the network. The base concatenates information symbols with a preamble corresponding to a destination remote unit. One or more remote units communicating with the base each concatenates information symbols with a preamble corresponding to that remote unit. An adaptive receiver system for a base unit rapidly adapts optimal despreading weights for reproducing information symbols transmitted from multiple remote units. A transmitter system for a base unit concatenates information symbols with a preamble associated with a remote unit in the cell. An adaptive receiver system for a remote unit in a communication network rapidly adapts optimal weights for reproducing a signal transmitted to it by a specific base unit in the network.

Abstract: A method and system of reliably detecting a reactive jamming attack and estimating the jammer's listening interval for exploitation by a communication system comprises channelizing one or more signals of interest (SOI), channelizing one or more signals of unknown origin (SUO), identifying frequency support patterns for the SOI and SUO using Bayes thresholds, comparing SOI and SUO detection map histories, and determining a percent match, where a match percentage above a specified minimum indicates a reactive attack. Edge detection can be used to enhance jammer support. Embodiments further detect reactive jammer adaptation to changes in the SOI's frequency support. Embodiments include detectors that are insensitive to jammer modulation and/or signal type. A jammer reaction delay and/or size and periodicity of receive window can be detected. Embodiments determine if a jammer is copying and retransmitting the SOI's waveform(s), and/or if the jammer is anticipatory.

Abstract: Methods and systems are described for causing orthogonal frequency division multiplexing (OFDM) transmission of various portions of data via various nodes. For example, a first portion of the data may be transmitted, via a first node and using OFDM, to at least a second node. Based on one or more observed capacities associated with one or more nodes (such as the first node and/or another node), it may be determined that a second portion of the data is to be routed via a different node (such as a third node) for transmission. The second portion of the data may be transmitted, via the third node and using OFDM, to at least the second node.

Abstract: Methods and systems are described for causing orthogonal frequency division multiplexing (OFDM) transmission of various portions of data via various nodes. For example, a first portion of the data may be transmitted, via a first node and using OFDM, to at least a second node. Based on one or more observed capacities associated with one or more nodes (such as the first node and/or another node), it may be determined that a second portion of the data is to be routed via a different node (such as a third node) for transmission. The second portion of the data may be transmitted, via the third node and using OFDM, to at least the second node.

Abstract: Methods and systems are described for determining a plurality of transmission levels for, e.g., a plurality of time-frequency channels and/or a plurality of tones. The transmission levels may be determined by a first node based on, for example, a received transmission from a second node. The first node may generate a signal, which may be based on, for example, an originator-based pseudorandom sequence, a recipient-based pseudorandom sequence, and/or a complex sinusoid. The first node may transmit the signal as an orthogonal frequency division multiplexing (OFDM) transmission.