A flexible Mth power carrier phase estimation algorithm for coherent optical receiver

Abstract

Although Mth power carrier phase estimation (PE) algorithm has been investigated intensively in coherent optical phase-shift-keying (PSK) system, block length effect impacts system performance and increases hardware complexity. In this paper, a flexible Mth power carrier PE algorithm is proposed to remove the effect of block length on system performance. We take into account the time-varying phase noise, instead of the assumption of constant phase noise over the entire observation interval. The weighted factors obtained from maximum likelihood method are introduced to eliminate the block length effect. Furthermore, we derive the analytical expression of phase error variance for the performance prediction of coherent receiver with the flexible Mth power. Bit error ratio (BER) performance of coherent receiver is evaluated and compared through both theoretical derivation and Monte Carlo simulation. The results show that by using the flexible Mth power algorithm, signal noise ratio (SNR) improvement over conventional Mth power algorithm with fixed block length of 20 and 40 at BER of 10−5 is 0.47dB and 2.18dB, when the linewidth per laser is 2MHz. By employing our flexible Mth power algorithm, SNR improvement over conventional Mth power algorithm with optimum block length will be larger as increasing laser linewidth . It means our flexible Mth algorithm is more effective for mitigating phase noise than the conventional Mth power algorithm.