Joint symbol, amplitude, and rate estimator
View Patent ↗The system in one embodiment relates to tightly integrating parameter estimation, symbol hypothesis testing, decoding, and rate identification. The present invention provides Turbo-decoding for joint signal demodulation based on an iterative decoding solution that exploits error correction codes. The system iteratively couples an initial amplitude estimator, a symbol estimator, a bank of decoders, and a joint amplitude estimator to produce the symbol estimates.
1. An apparatus for processing a digital data stream from multiple users, comprising:
an initial amplitude estimation unit processing said data stream and producing initial amplitude estimates on a first iteration;
a joint amplitude estimator coupled to said data stream and said initial amplitude estimator, wherein said joint amplitude estimator produces updated amplitude estimates;
a symbol estimator coupled to said data stream, said initial amplitude estimator, and said joint amplitude estimator, wherein said symbol estimator produces a plurality of symbols estimates for each user; and
a bank of decoders coupled to said symbol estimator, producing a plurality of symbol likelihood estimates for each user, wherein said symbol likelihood estimates are iteratively fed back to said symbol estimator and said joint amplitude estimator until a final condition is obtained.
2. The apparatus according to claim 1 , wherein said final condition is selected from at least one of the group consisting of: bit error rate metric level and fixed number of iterations.
3. The apparatus according to claim 1 , wherein said symbol estimator is a member selected from at least one member of the group consisting of: Minimum Mean Squared Error (MMSE), maximum likelihood, M-algorithm, T-algorithm, and Q-algorithm, decorrelating decision-feedback detector (DDFD), improved decorrelating decision-feedback detector (IDDFD), successive interference cancellation (SIC), parallel interference cancellation (PIC) and multi-stage detector; block-iterative interference cancellation, and a deferred decorrelating decision-feedback detector.
4. The apparatus according to claim 1 , further comprising an energy detector coupled to said joint amplitude estimator.
5. The apparatus according to claim 1 , wherein said bank of decoders are decoders selected from at least one decoder of the group consisting of: Soft-output Viterbi, Maximum A Posteriori, and Bahl-Cocke-Jelinek-Raviv.