Patent attributes
A code-enhanced, multi-user detection, Reduced Algorithm Receiver in a multiuser communication system reduces the signal processing requirements by limiting the number of searches between consecutive symbol cycles using information from an encoder state diagram. The Receiver makes use of a convolutional encoder's state machine properties to mark possible transitions as invalid based on the current state of the multiple users'encoders, thus removing them from the search tree. The Reduced Algorithm Receiver comprises a Signal Sampler for converting a single composite waveform signal (Rx) to digitized composite signal (DRx), a Parameter Estimator for determining waveform characteristics of each of the multiple users, a Memory for storing predetermined training sequences for each of the users, a Next State Predictor that reduces the amount of symbols being checked during a current cycle, a Waveform Approximator that receives the user waveform characteristics data and a set of possible bits from the next state predictor and attempts to simulate modulation of the individual user signal, a Demodulator for comparing the set of possible composite waveforms (˜Tx) from the Waveforms Approximator to the digitized composite waveforms (DRx) and determining the best match waveform, and a Convolutional Decoder for receiving the best match symbols and decoding them for each of the users.
