Adaptive spreadspectrum systems using leastsquares lattice algorithms
Abstract
Practical communication systems must cope with many uncertainties in addition to determining the transmitted data, e.g., the direction, timing, and distortion of the desired signal, and the spectral and spatial distribution of the interference, all of which may change with time. This paper describes exact leastsquares (LS) recursive lattice algorithms which resolve these uncertainties in a directsequence spreadspectrum digital communication system. The adaptive LS algorithm is recursive both in order and time, and converges rapidly to the uncertain parameters. Timediscrete algorithms may be mechanized by a receiver containing integrateanddump circuits operating at the chip rate of the pseudonoise (PN) sequence, one in each inphase and each quadrature channel of each sensor array element's output. Different configurations of optimal timediscrete receivers are presentd and transformed into adaptive receivers by taking advantage of the spectral properties of the different kinds of LS filters. Simulation results are presented and some guide lines are given for the architecture of an adaptive directsequence spreadspectrum system.
 Publication:

IEEE Journal on Selected Areas in Communications
 Pub Date:
 September 1985
 Bibcode:
 1985IJSAC...3..652R
 Keywords:

 Adaptive Filters;
 Lattices (Mathematics);
 Least Squares Method;
 Noise Reduction;
 Spread Spectrum Transmission;
 Equalizers (Circuits);
 Pseudonoise;
 Receivers;
 Recursive Functions;
 Signal To Noise Ratios;
 Communications and Radar