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Spreading Sequence Estimation Based on Constant Modulus Property for QPSK-DSSS Signals
Received date: 2012-11-10
Revised date: 2013-02-25
Online published: 2013-03-01
Supported by
National Natural Science Foundation of China (61201282);Science and Technology on Communication Information Security Control Laboratory Foundation (9140C130304120C13064)
In this paper, a spreading sequence estimation algorithm based on constant modulus property is proposed for the QPSK-DSSS signals in low signal to noise ratio and non-cooperative scenarios. First, the single-user QPSK-DSSS signal can be equivalently represented as a two-user BPSK-DSSS signal, and then the two-dimensional signal subspace spanned by the in-phase and quadrature binary spreading sequences is estimated by the eigen-decomposition of the covariance matrix. Finally, to estimate the spreading sequences accurately, its constant modulus property is exploited to cope with the unitary matrix ambiguity resulting from eigen-decomposition. The proposed algorithm is simple and easy to implement, and has a lower computational complexity compared to existing methods. And simulation results demonstrate the significant performance gains of the proposed algorithm in low signal to noise ratio situations.
ZHANG Huaguo , WEI Ping . Spreading Sequence Estimation Based on Constant Modulus Property for QPSK-DSSS Signals[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2013 , 34(6) : 1389 -1396 . DOI: 10.7527/S1000-6893.2013.0126
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