On the Use of Delay-Decorrelated I/Q Test Sequences for QPSK and QAM Signals

Author

Sierra, Alberto ; Randel, Sebastian ; Winzer, Peter J. ; Ryf, Roland ; Gnauck, Alan H. ; Essiambre, René-Jean

Author_Institution

Bell Labs., Alcatel-Lucent, Holmdel, NJ, USA

Volume

24

Issue

12

fYear

2012

fDate

6/15/2012 12:00:00 AM

Firstpage

1000

Lastpage

1002

Abstract

We report on limitations of the commonly used method to generate complex optical signal constellations from delay-decorrelated copies of a bit sequence to modulate in-phase (I) and quadrature (Q) components of a signal constellation. Using closed-form analytical solutions, numerical simulations, and an experimental verification, we show that I/Q delays shorter than the combined channel and adaptive equalizer length can result in artificial improvements of the measured bit-error ratio.

Keywords

adaptive equalisers; delays; error statistics; optical fibre communication; optical modulation; optical testing; quadrature amplitude modulation; quadrature phase shift keying; I/Q delays; QAM signals; QPSK signals; adaptive equalizer length; bit sequence; bit-error ratio measurement; closed-form analytical solutions; combined channel length; complex optical signal constellations; delay-decorrelated I/Q test sequences; delay-decorrelated copies; experimental verification; modulate in-phase components; modulate quadrature components; numerical simulations; Adaptive equalizers; Bit error rate; Correlation; Crosstalk; Gain; Phase shift keying; Adaptive equalization; Wiener filter; spatial multiplexing;

fLanguage

English

Journal_Title

Photonics Technology Letters, IEEE

Publisher

ieee

ISSN

1041-1135

Type

jour

DOI

10.1109/LPT.2012.2192423

Filename

6179515