Multiplier-free QPSK phase recovery for coherent intersatellite optical wireless communication

In this paper, a quadrature phase shift keying (QPSK) phase-recovery algorithm is presented for coherent intersatellite optical wireless communication (IsOWC).From a theoretical perspective, we explain the process of the multiplier-free algorithm.Through simulations, we analyze key parameters and provide guidance on their optimal selection.Additionally, the proposed algorithm maintains stable phase tracking at bit energy to noise power spectral density (Eb/N0) as low as 4 dB.In an ob2b transmission test, our algorithm achieved a sensitivity of -49 dBm @5 Gbps QPSK [hard-decision forward-errorcorrection (HD-FEC) limit].Compared to the Viterbi and Viterbi phase-recovery (V&V) algorithm, its receiving sensitivity is improved by 1 dB, resulting in a link distance extension of 1100 km.Our multiplier-free and robust algorithm meets the requirements of IsOWC systems and shows promise for future applications.