Sequence acquistion using bit estimation techniques.
Information Sciences: an International Journal
MILCOM'06 Proceedings of the 2006 IEEE conference on Military communications
Iterative message passing techniques for rapid code acquisition
MILCOM'03 Proceedings of the 2003 IEEE conference on Military communications - Volume I
Differential acquisition of m-sequences using recursive soft sequential estimation
IEEE Transactions on Wireless Communications
A new approach to rapid PN code acquisition using iterative message passing techniques
IEEE Journal on Selected Areas in Communications
PN Code Acquisition Using Belief Propagation with Adaptive Parity Check Matrix
Wireless Personal Communications: An International Journal
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This paper addresses the problem of recovering the code phase of the composite spreading sequence for a CDMA 1x signal transmitted from a handset, without the benefit of a priori information from the system. The spreading code is required for the radio spectrum monitoring system for signal detection and measurements rather than for communications. The structure of the CDMA 1x signal is exploited by processing sequential pairs of received samples to form a single soft sample for each pair. The approach models the combination of the long-code generator and the two short-code generators, along with the pairwise processing, by a single linear system over GF(2), with the initial states of the long- and short-code generators forming the input vector. Consequently, a vector of the pair-wise soft samples can be treated as a noisy received codeword that is decoded using iterative soft-in decoding techniques. If the decoder yields the correct candidate "codeword," the original states of the code generators can be computed. This approach does not require direct access to the transmitted spreading sequence but can be applied to the data modulated signal. Simulation results provide performance estimates of the method with noise, Rayleigh fading, and co-channel interference.