A modified sequential acquisition scheme in direct-sequence spread-spectrum communications over a fading channel

A modified sequential acquisition scheme is proposed in this letter to avoid the significant high error probabilities (false alarm and missing probabilities) occurring with the conventional sequential acquisition scheme in direct-sequence spreadspectrum systems while a high' frequency offset is present. A new estimator of jf- is also designed to effectively solve the problems caused by the channel fading effects: Extensive computer simulation results have indicated that the proposed technique can achieve the desired low error probabilities and furthermore its performance is very close to that with the perfect channel estimation.