Multicarrier DS-SS for GPS Pseudolites: Code-Acquisition Performance in the Presence of Data Modulation

In this paper, we analyze the code acquisition performance of a multicarrier direct-sequence spread spectrum (DS-SS) system in the presence of data modulation (i.e., no pilot) on multipath Rayleigh fading channels. The motivation of this analysis arises from the possibility of beneficially using multicarrier DS-SS in global positioning system (GPS) pseudolites, where unmodulated pilot is not available. We consider equal gain combining (EGC) and selection combining (SC) of subcarrier correlator outputs for each timing hypothesis. We evaluate probability of incorrect decision and mean acquisition time performance of the multicarrier DS-SS code acquisition scheme. We show that significant reduction in the mean acquisition time (MAT) can be achieved using the multicarrier DSSS approach for GPS pseudolites.