Bit-error rate performance of coherent optical M-ary PSK/QAM using decision-aided maximum likelihood phase estimation

S. Zhang, P. Y. Kam, J. Chen, Changyuan Yu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

44 Citations (Scopus)


The bit-error rate (BER) expressions of 16- phase-shift keying (PSK) and 16- quadrature amplitude modulation (QAM) are analytically obtained in the presence of a phase error. By averaging over the statistics of the phase error, the performance penalty can be analytically examined as a function of the phase error variance. The phase error variances leading to a 1-dB signal-to-noise ratio per bit penalty at BER=10-4 have been found to be 8.7 × 10-2 rad2, 1.2 × 10-2 rad2, 2.4 × 10-3 rad2, 6.0 × 10-4 rad2 and 2.3 × 10-3 rad2 for binary, quadrature, 8-, and 16-PSK and 16QAM, respectively. With the knowledge of the allowable phase error variance, the corresponding laser linewidth tolerance can be predicted. We extend the phase error variance analysis of decision-aided maximum likelihood carrier phase estimation in M-ary PSK to 16QAM, and successfully predict the laser linewidth tolerance in different modulation formats, which agrees well with the Monte Carlo simulations. Finally, approximate BER expressions for different modulation formats are introduced to allow a quick estimation of the BER performance as a function of the phase error variance. Further, the BER approximations give a lower bound on the laser linewidth requirements in M-ary PSK and 16QAM. It is shown that as far as laser linewidth tolerance is concerned, 16QAM outperforms 16PSK which has the same spectral efficiency (SE), and has nearly the same performance as 8PSK which has lower SE. Thus, 16-QAM is a promising modulation format for high SE coherent optical communications.
Original languageEnglish
Pages (from-to)12088-12103
Number of pages16
JournalOptics Express
Issue number12
Publication statusPublished - 7 Jun 2010
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this