System for reducing the affects of signal fading on received sig

Details System for reducing the affects of signal fading on received sig System for reducing the affects of signal fading on received sig

1991-02-07

1993-03-02

Kuntz, Curtis

Pulse or digital communications

Spread spectrum

Direct sequence

375 40, 375 94, 375101, 455137, 455273, H04B 702, H04L 102

Patent

active

051915987

ABSTRACT:
Signals in synchronizing sequences and data sequences are transmitted over a fading channel to a Viterbi-receiver. The signals are received by antennas and sampled to received antenna signals (s.sub.in,r (k)). Part channel estimates (h.sub.est,r) for the individual antennas are formed. For Viterbi-analysis, assumed input signals (s.sub.a,r (.DELTA.T.sub.ij,k)) for the data sequence are produced with the aid of the part channel estimates (h.sub.est,r). Part metric values (m.sub.r (.DELTA.T.sub.ij, k)) are formed as a difference between the received antenna signal (s, .sub.in,r (k)) and corresponding assumed input signals (s.sub.a,r (.DELTA.T.sub.ij, k)) for Viterbi state transitions (.DELTA.T.sub.ij). For one state transition there is formed a metric value such as the sum of a metric value ((M(T.sub.j, k-1)) for an old state (T.sub.j) at a preceding sampling time point (k-1) increased with a weighted (K.sub.r) sum of the part metric values (m.sub.r (.DELTA.T.sub.ij, k)) belonging to individual part channel estimates (h.sub.est,r). Corresponding metric values are formed for all state transitions to the new state (T.sub.i) and the smallest of these metric values is chosen in accordance with the Viterbi-algorithm.

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