Computationally efficient blind code synchronization for asynchronous DS-CDMA systems with adaptive antenna arrays (Q2570473)

Summary: A novel space-time adaptive near-far robust code-synchronization array detector for asynchronous DS-CDMA systems is developed in this paper. There are the same basic requirements that are needed by the conventional matched filter of an asynchronous DS-CDMA system. For the real-time applicability, a computationally efficient architecture of the proposed detector is developed that is based on the concept of the multistage Wiener filter (MWF) of Goldstein and Reed. This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigendecomposition of a covariance matrix. As a consequence, this detector achieves a complexity that is only a linear function of the size of antenna array (\(J\)), the rank of the MWF (\(M\)), the system processing gain (\(N\)), and the number of samples in a chip interval (\(S\)), that is, \(\mathcal{O}(JMNS)\). The complexity of the equivalent detector based on the minimum mean-squared error (MMSE) or the subspace-based eigenstructure analysis is a function of \(\mathcal{O}((JNS)^3)\). Moreover, this multistage scheme provides a rapid adaptive convergence under limited observation-data support. Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the \(J\)-element antenna array, the amount of the \(L\)-sample support, and the rank of the \(M\)-stage MWF. The performance advantage of the proposed detector over other DS-CDMA detectors is investigated as well.