Bae Systems Information and Electronic Systems Integration Inc.

Collision Communications, Inc.

Other

Joshua D Niedzwiecki

Robert B MacLeod

Matthew A Taylor

Brandon P Hombs

John A Tranquilli, Jr

Prabahan Basu

Joseph Farkas

Karl D Brommer

Rachel E Learned

Thomas P McElwain

Leonard E Russo

Kari M Karwedsky

Mark Lande

Amber L Silva

A distributed transmit platform deception network array system includes a plurality of platforms; each platform comprising at least one transmitter; wherein the platforms are in a geographically distributed configuration with respect to each other and at least one victim receiver; a propagating wavefront is generated by the transmitters of the plurality of platforms toward the at least one victim receiver according to deception target characteristics for each identified victim receiver; whereby the propagating wavefront is controlled, and a false location is determined by the victim receiver, Whereby detection of a deception at alternate receiver locations is minimized by selection of characteristics of the transmitted waveform.

Radio frequency deception network

A method and apparatus are disclosed that apply multiuser detection (MUD) analysis to an aggregated RF response from a plurality of simultaneously queried RFID tags, so as to distinguish the individual tag responses. The claimed method thereby significantly reduces RFID detection latency when multiple tags are simultaneously queried. Some embodiments transmit carrier waves at more than one frequency, such as a plurality of equally-spaced frequencies, so as to enhance the MUD analysis by incorporating a multi-frequency dimension. Other embodiments incorporate additional spatial dimensions by deploying multiple RF detection antennae at separated locations. The number of colliding tag responses must be estimated before MUD analysis can be applied. In some embodiments other signal parameters must be estimated, such as signal bias and an impulse function for each responding tag that characterizes alterations of the RF signal while in transit due to propagation distance, passage through intervening objects, and reflections.

Method for simultaneously detecting a plurality of RFID tags using multiuser detection

A method is disclosed for increasing the communication capacity of a shared ad-hoc wireless channel by using multiuser detection (MUD) to distinguish overlapping information transmitted simultaneously by a plurality of nodes. The transmitting nodes simultaneously provide parameter-estimating signals over separate, unshared, low-rate parameter channels generated using orthogonal frequencies, spread spectrum technology, or time multiplexing. Receiving nodes use these separate, non-overlapping parameter-estimating signals to estimate MUD-required signal parameters such as amplitude, phase, and frequency offset, thereby enabling use of lower complexity MUD receivers, because the parameters are not estimated in the presence of other interference. Node ID, spreading code type, and/or other information can also be transmitted over the parameter channels. Limiting the number of parameter channels can limit the maximum number of transmitting nodes. Amplitudes of parameter channel transmissions can be greater than communication channel transmissions by a known ratio. Parameter channels can be frequency-hopped for jam-resistance.

Media access control protocol for multiuser detection enabled ad-hoc wireless communications

Method for simultaneous detection of a plurality of RFID tags using multiuser detection

A system and method for selecting an optimal frequency channel to communicate on in a wireless network is disclosed. The optimal frequency is selected from a predefined set of frequencies for all nodes to communicate on based on an exposure calculation. All underlay nodes collect initial SNR information from initial detection of other nodes and adjust their transmit power for an intended receiver such that the signal is received at the lowest allowable underlay-to-overlay power ratio, thus minimizing exposure. The desired underlay-to-overlay ratio is set based on how much we are capable of cancelling the overlay signal and the SINR at which a signal can be recovered such that the data can be successfully received from the underlay node. The optimal channel selected by this algorithm is the one with the least area of undesired exposure, or least probability of interfering with the primary user. The performance increases as a function of number of nodes, or data points.

Coordinated optimization of underlay network communication for efficient use of spectrum

A QR-RLS adaptive digital filter provides fast computation without excessive computational resources. 18-bit multipliers enhance speed, and a floating point inverse square root block adjusts dynamic range in 12-dB steps. A memory stores two P-matrix copies, one being delivered with rows shifted according to the clock speed so as to enhance pipeline processing. Embodiments reliably detect modulation schemes, demodulate strong signals by passing feedback bits between multiple stages, remove impulses due to lightening, etc, erase symbol estimates which exceed an error threshold, and add high frequency noise to avoid mathematical divergence caused by excessive S/N. A genetic method is provided for identifying asynchronous spreading codes with minimum correlations, whereby randomly selected candidates compete based on Frobenius norms of their correlations, the weakest being discarded and the process being iterated. A method is provided for selecting optimal filter sampling windows for simultaneously detected symbol streams having relative timing delays.

QR-RLS adaptive digital filter with 18-bit pipeline architecture

A multi-port junction is fed with a frequency-stepped source and has one of its ports connected to an antenna that can serve either as a transmit-and-receive antenna or as a receive antenna only, with the outputs of the multi-port junction being used to estimate a complex reflection coefficient for each frequency of interest. The subject system requires no IF stages, down-conversion mixers or oscillators, and therefore may be provided adjacent each antenna at low cost. An embodiment involving co-located separate transmit and receive antennas is used to minimize the power requirements for the multi-port junction, whereas in a third embodiment, an array of transmit/receive antennas is used, fed by the same RF source but in which digitally-controlled phase shifters are used for beam-forming purposes.

Stepped frequency radar

A multiuser detector system with correlation based pruning including a parameter estimation module adapted to receive complex signals, and to produce estimated signature waveforms for each of K co-channel interfering signals. Pre-processing the estimated signature waveforms using an S-matrix module and producing a more valid set of hypotheses, wherein the S-matrix module uses apriori knowledge of an unnormalized cross correlation matrix, and processing the more valid set of hypotheses for pruning with an M-algorithm in a multiuser detector module. An improvement to the M-algorithm in which the interference structure based on the signal correlation matrix used during the optimization process aids in selecting a better subset of hypotheses to test. This approach has the benefit of reducing computational complexity and improving performance over the existing M-algorithm.

M-Algorithm multiuser detector with correlation based pruning

In the invention, a four-port junction () has a port () connected to an RF signal source (). The four-port junction () also has an antenna port () coupled to a combined transmit/receive antenna (). Two ports () of the four-port junction () develop output power that is applied to an analogue-to-digital converter (), that is in turn coupled to a central processor (), that is in turn coupled to a user interface ().

A calibration system is provided for calibrating frequency domain reflectometers in the field by using both the scattering parameters of the multi-port junction determined at the factory and changing the offset and gain terms used in generating a complex reflection coefficient by using internal calibrated loads so that heavy, cumbersome external calibrated transmission lines are not required. In one embodiment the internal calibrated loads include RLC circuits and in another embodiment the internal calibrated loads include attenuators. Further, retesting or recalibration does not necessitate reconnecting the cable under test, which may remain connected to the reflectometer's test port throughout the procedure.

Method and apparatus for calibrating a frequency domain reflectometer

Techniques for compensating for frequency mismatch between transmitters and receivers of a multiuser communication system having a plurality of users are disclosed. In particular, the mismatch of carrier frequency estimates are estimated and compensated for each user of the system. This is accomplished without increasing the training overhead of the system. Symbol phase drift and offset is computed by estimating phase error profile parameters (e.g., slope and offset). The disclosed techniques may be used to correct for symbol rotation in any one decision region, or in neighboring decision regions.

Frequency mismatch compensation for multiuser detection

A digital receiver automatically detects and non-coherently demodulates a multiplicity of interfering digitally modulated signals transmitted simultaneously at approximately the same carrier frequency. The receiver includes one or more antenna inputs (e.g., polarization and/or space diverse), a parameter estimator module, and a multiuser detector for estimating the data transmitted by each interfering signals and adapted to operate with at least one of a MUD algorithm with partially quantized prior information and a MUD algorithm based on prewhitened data.

Co-channel interference receiver

A four-port junction is substituted for a six-port junction in a frequency domain reflectometer, which reduces the parts count and therefore cost and size of the reflectometer while improving reliability. The frequency domain reflectometer can alternatively be used as an insertion loss tester. An algorithm including the Hilbert Transform is used to directly calculate the estimated reflection coefficient from the output power measured at only two output ports.

Reduced complexity transmission line and waveguide fault tester

A Parameter Estimator for accurately estimating signature responses of multiple co-channel interfering digital transmission signals. The Parameter Estimator is used in a Multiuser Detection (MUD) Receiver to significantly reduce the error rate. The Parameter Estimator comprises a plurality of software components, including a Signature Waveform Estimator, Training Sequence Locator, Noise Estimator, Active Users Tester, Initial Transformation Matrix Builder, a Transformation Matrix Rebuilder, and a Transformation Matrix Selector, and generates an estimated noise power, a training sequence index and estimated signature waveforms.

Growing community of inventors

Manchester, NH, United States of America

Joshua D Niedzwiecki