Noncoherent hybrid acquisition of DS/CDMA signals

A noncoherent signal acquisition scheme using hybrid active correlation for a direct sequence code division multiple access (DS/CDMA) receiver is presented. A test based on sequential hypothesis testing called the M-ary sequential probability ratio test (MSPRT) and several fixed sample size (FSS) tests are considered for the testing stage. Continuous integration of in-phase and quadrature signal components is used to minimize noncoherent combining losses. The MSPRT is adapted accordingly to accommodate dependent samples from the integrator output. Results of analysis and simulation show that the IMSPRT provides significantly better performance than the FSS schemes. It has been found that use of the IMSPRT with continuous integration results in negligible noncoherent implementation loss (compared to coherent acquisition) when a moderate number of correlators are used