Optimized Carrier Frequency and Phase Recovery Based on Blind $M$ th Power Schemes

We report an optimized hardware scheme for carrier frequency and phase recovery algorithms based on Mth-order power schemes for flexible intradyne coherent receivers. The phase recovery is based on the traditional Viterbi & Viterbi algorithm with a feedforward architecture, which requires an Mth-order power nonlinear operation. The output of such operation is also used in the differential phase-based approach for frequency offset estimation by means of a feedback loop. Hence, by using a single Mth-order operation, the reported architecture saves approximately half of the hardware resources for quadrature phase shift keying (QPSK) in the frequency recovery stage compared with fully independent phase and frequency algorithms. The evaluation of the accuracy of the proposed method is performed with digital signal processing in real-time using a field-programmable gate array (FPGA) for differential QPSK and 8PSK modulation formats. No significant performance penalty is observed when compared with an implementation featuring independent algorithms.