Synchronized users signals are subtracted from received signal at the base station of a direct sequence code division multiple access (DS/CDMA) system to aid code acquisition of new users. Expressions for expectation and variance of the correlator output corresponding to a synchronization, chip and otherwise are derived for the asynchronous environment. A novel detector based on a posteriori probability threshold rule is proposed for code acquisition. Computer simulations show significant performance improvements over conventional code acquisition methods. The technique is also applicable for signals modulated by Markov codes and computer simulations show superiority of Markov codes over independent and identically distributed (i.i.d.) codes.
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