Modeling of non-coherent sequential acquisition process for DS/SS signals

A modified non-coherent sequential detection decision logic based on continuous accumulation to achieve fast PN code acquisition is proposed. To simplify the design and analysis. the equivalent relationship between the likelihood ratio of the current sample and that of all the previous samples is deduced. The scheme is proved to be an optimum sequential detection under certain assumptions. Because the average sample number (ASN) can not be calculated through the methods applied to the conventional sequential detection, an algorithm is also provided, which can estimate both the probability density function (pdf) and the upper threshole of ASN. The desired probabilities of false alarm and detection, as well as faster PN code acquisition compared to the conventional sequential detection can be achieved by employing this structure. In addition, Rayeigb-faded reception case is also Taken into consideration. Performances of the proposed schemes are obtained, which suggest that the proposed non-coherent sequential detection is more desirable.