Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7929852 | Optics Communications | 2015 | 7 Pages |
Abstract
This paper proposes a simple three-stage carrier phase estimation (CPE) algorithm for 16-ary quadrature amplitude modulation (16-QAM) optical coherent systems, based on a simplified quadrature phase shift keying partition (QPSK-partitioning) scheme for the first stage and the maximum likelihood (ML) detection for the second and the third stage. Only 25% of the symbols of 16-QAM systems are employed for the first stage phase estimation, while only 50% are used for the second stage phase estimation. Therefore, the computational complexity of the proposed three-stage CPE algorithm for 16-QAM systems is similar to that of the QPSK-partitioning+ML algorithm. The performance of two different ML detections is compared and the simulation results show that the “constellation-assisted” ML detection can achieve better linewidth tolerance performance than the “conventional” ML detection for 16-QAM systems. A combined linewidth symbol duration product of 1Ã10â4 is tolerable for a signal noise ratio (SNR) sensitivity penalty of 0.8Â dB at a BER of 1Ã10â3, based on the block averaging instead of the sliding window averaging. A good bit error rate (BER) performance for the proposed three-stage CPE algorithm is achieved especially at high SNR levels in the simulation. The performance of the proposed three-stage CPE algorithm is similar to that of the BPS algorithm with 22 test phase angles, but with reducing the computational complexity by a factor of about 5.3.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
Yin Chen, Xuguang Huang,