New SNR Estimation Methods in Digital QPSK Receiver

W. Fu, J. Jiang, S. Wang, and S. Liu (PRC)


Satellite communications, maximum likelihood estimation, SNR estimation, quadrature phase-shift keying


From derivation of SNR maximum likelihood estimator based on data directed decision, we concluded it is a biased estimator, and an unbiased estimator can be acquired through high order moments of received data. Then, we developed two SNR estimators based on iteration method. One is solving the QPSK NDA maximum likelihood equation by gradient approximation, which has better convergence performance than other methods. The other is based on the statistical parameters of received data, which not only makes received data buffering unnecessary, but also reduces iteration calculation greatly compared with other iteration methods, and more important, not at the cost of estimation performance degradation. Finally, we compared several SNR estimators in performance and complexity of their calculation.

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