Analysis of a serial acquisition scheme for unslotted distributed direct-sequence packet radio networks

This paper investigates the problem of acquisition in unslotted distributed direct-sequence packet radio networks. A noncoherent serial acquisition scheme is considered that uses passive matched filters to detect packet headers. A new Gaussian approximation is derived to model the effects of multiple-access interference during acquisition. This approximation takes into account oscillator inaccuracies and Doppler shifts, and its validity depends only on the presence of a sufficient number of chips in the acquisition header. In particular, the accuracy of the approximation is not contingent on the presence of a large number of equal-power interferers. False alarm processing is modeled and a simple expression for the probability of acquisition is derived. The problem of threshold selection is considered and it is shown that a single threshold can be chosen to provide acceptable performance in a wide range of channel conditions