Abstract: A method and system for communicating a message are disclosed. An exemplary system includes plural nodes and an exemplary information transmitter that includes a processor. The processor can detect a number of the nodes within communication range of the information transmitter as helper nodes. The processor can process a message into a number of portions as a function of the number of helper nodes detected. The processor can transmit at least one of the portions of the message to at least one of the helper nodes for wireless communication of at least one portion by the at least one helper node.

Abstract: A tactical radio includes a radio frequency (RF) processing module having a receiving component path and a transmitting component path. A signal processing module coupled to the RF processing module includes a jammer detection stage for identifying a type of jamming signal on a channel over which communications signals are received simultaneously. A jammer model stage in the signal processing module produces a waveform model for the jamming signal, and a channel model stage replicates propagation conditions on the channel and produces a corresponding cancellation signal. The cancellation signal is coupled at such a level into the receiving component path so as to cancel the jamming signal from received communications signals at the front end of the radio. Any residual jamming signals may then be removed by a secondary jamming cancellation stage operating at baseband.

Abstract: A digital wireless communication system for increasing the number of users capable of communicating over a network permits multiusers to transmit information simultaneously on the same channel of frequency. The primary example of such a system would be that employing radio frequency transmissions, even optical transmissions; however, the invention will also apply to magnectic detections such as in the reading of information stored on a magnetic tape. It is possible to increase overall throughput in terms of total number of bits transmitted through the shared medium by all users of a multiple access system if the signals are allowed to interfere. The present invention provides a multiuser detection process and apparatus that is capable of pulling apart signals in heavy interference in real time by combining the signals received from two or more spatially seperated collectors or antennas.

Abstract: A Tree-structured multicarrier multiple access communication system in a multiple access environment having a number of interfering signals. In one embodiment an environment estimator estimates and tracks the number of interfering signals of the environment. A code selector determines an optimal spreading code represented by the environment, and identifies an actual spreading code that is closest to the optimal spreading code. A signal transmitter can then be used to transmit a multicarrier multiple access signals in accordance with the actual spreading code identified. On the receiver side, a multiuser detector (MUD) module performs tree structured multiuser detection signal processing, and produces a bit stream for each interfering signal.

Abstract: The present invention is a digital communication method that increases the overall throughput of a Multiuser Detection (MUD)-based co-channel multiple access (MA) system in terms of the total number of bits transmitted through the shared medium by all the users of the MA system if signals are allowed to interfere. The total number of users can be increased if more dimensions are used for assigning the transmitted signals and the same dimensions are measured at the receiver. Specifically, the present invention does not require any coordination among transmitters but simply requires a transmitter to send its signal with either a randomly chosen polarization ellipse, or an assigned or randomly chosen amplitude level.

Abstract: The present invention is a high quality real-time Turbo-Mud processing system initially employing a high complexity multi-user detector that results in better estimates of the bit streams, and then the remaining iterations employing a computationally low linear-based-MUD/Turbo-MUD. The present approach uses more computational computations at the first iteration, and less computations on subsequent processing due to cycling through the Turbo-Mud process with a low complexity sub-optimal detector that significantly cleans up the estimates in a few iterations of the Turbo-MUD. The present invention also provides an efficient means of estimating symbols transmitted in a multi-user environment in overloaded or super-saturated conditions.

Abstract: A multi-user decoder is disclosed in which interfering users are assigned to levels of a decoding tree constructed in the decoder dependent on the power levels of the user's received signals and for each symbol interval. By building the decoding tree in this manner for each symbol interval, a reduced complexity search is more likely to include paths and nodes in the tree containing the correct value for the channel symbols.

Abstract: Techniques for reading data from a storage medium (150) having a high track density prone to adjacent track interference are disclosed. One or more sensing elements (120) are used to extract data stored on adjacent tracks. Multiuser detection (130) is then used to detect/decode a single track that is closely spaced to its neighboring tracks, resolve interference from adjacent tracks, or to simultaneously detect/decode multiple adjacent closely packed tracks.

Abstract: 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.

Abstract: A system is provided for increasing the number of users capable of communicating over a wireless network to permit multiple users to transmit information simultaneously on the same channel or frequency in which a Viterbi decoder-based signal separation system is used to pull apart or uncorrupt the otherwise interfering signals on the channel. In one embodiment, two users are assigned to the same channel, with a joint parameter estimation pre-processor being utilized to provide an estimation of the power, time and frequency offsets and phase of the incoming signals. The joint parameters estimated by the parameter estimation unit are applied to a signal separator which recovers and pulls apart the two signals.

Abstract: In a multi-user detection system in which interfering signals are purposely allowed to exist, a parameter estimation unit is provided which utilizes signal processing for determining the channel transfer function for each received signal, including the received power, phase of the oscillator, timing offset relative to the base station clock carrier frequency offset, and number of multipaths replicas and delays for each replica, with the system providing realtime uninterrupted estimates of these parameters required by the signal separation unit.

Abstract: The present invention is a digital communication method that increases the overall throughput of a MUD-based co-channel multiple access (MA) system in terms of the total number of bits transmitted through the shared medium by all the users of the MA system if signals are allowed to interfere. The total number of users can be increased if more dimensions are used for assigning the transmitted signals and the same dimensions are measured at the receiver. Specifically, the present invention does not require any coordination among transmitters but simply requires a transmitter to send its signal with either a randomly chosen polarization ellipse, or an assigned or randomly chosen amplitude level.

Abstract: A real-time multi-user detection (MUD) receiver processing simultaneous digitally modulated interferers and transmissions in the same frequency optimizing performance for heavily loaded and overloaded multiple access systems by implementing an iterative TurboMUD receiver using tree-pruning, including confidence ordering, power-ordering, and a voting procedure. On the first iteration, user indices are ordered according to received powers. On subsequent iterations, the voting system provides soft decisions or confidence values utilized as soft inputs to single-user decoders. Voting is computationally attractive and allows the bank of decoders to operate on soft values, improving performance and reducing the number of turboMUD iterations. The bank of soft output error correction decoders produces an improved set of soft decisions or confidence values corresponding to the channel bits transmitted by each interfering user.

Abstract: A multi-user decoder is disclosed in which interfering users are assigned to levels of a decoding tree constructed in the decoder dependent on the power levels of the user's received signals and for each symbol interval. By building the decoding tree in this manner for each symbol interval, a reduced complexity search is more likely to include paths and nodes in the tree containing the correct value for the channel symbols.

Abstract: 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.

Abstract: A real-time multi-user detection (MUD) receiver processing simultaneous digitally modulated interferers and transmissions in the same frequency optimizing performance for heavily loaded and overloaded multiple access systems by implementing an iterative TurboMUD receiver using tree-pruning, including confidence ordering, power-ordering, and a voting procedure. On the first iteration, user indices are ordered according to received powers. On subsequent iterations, the voting system provides soft decisions or confidence values utilized as soft inputs to single-user decoders. Voting is computationally attractive and allows the bank of decoders to operate on soft values, improving performance and reducing the number of turboMUD iterations. The bank of soft output error correction decoders produces an improved set of soft decisions or confidence values corresponding to the channel bits transmitted by each interfering user.

Abstract: A system is provided for increasing the number of users capable of communicating over a wireless network to permit multiple users to transmit information simultaneously on the same channel or frequency in which a Viterbi decoder-based signal separation system is used to pull apart or uncorrupt the otherwise interfering signals on the channel. In one embodiment, two users are assigned to the same channel, with a joint parameter estimation pre-processor being utilized to provide an estimation of the power, time and frequency offsets and phase of the incoming signals. The joint parameters estimated by the parameter estimation unit are applied to a signal separator which recovers and pulls apart the two signals.

Abstract: In a multi-user detection system in which interfering signals are purposely allowed to exist, a parameter estimation unit is provided which utilizes signal processing for determining the channel transfer function for each received signal, including the received power, phase of the oscillator, timing offset relative to the base station clock carrier frequency offset, and number of multipaths replicas and delays for each replica, with the system providing realtime uninterrupted estimates of these parameters required by the signal separation unit.