Comparison Between PS-QPSK and PDM-QPSK With Equal Rate and Bandwidth

Polarization-switched quadrature phase-shift keying (PS-QPSK) is a recently introduced 4-D signal constellation that has a power efficiency (and sensitivity) advantage over polarization-division multiplexed QPSK (PDM-QPSK). Using a polarization-rotated form of PS-QPSK, we show that it is equivalent...

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Bibliographic Details
Published inIEEE photonics technology letters Vol. 24; no. 3; pp. 203 - 205
Main Authors Krongold, B., Pfau, Timo, Kaneda, N., Lee, S. C. J.
Format Journal Article
LanguageEnglish
Published IEEE 01.02.2012
Subjects
Bandwidth
Coherent detection
Encoding
Forward error correction
Multiplexing
Optics
Phase shift keying
polarization multiplexing
polarization-switched quadrature phase-shift keying (PS-QPSK)
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Summary:Polarization-switched quadrature phase-shift keying (PS-QPSK) is a recently introduced 4-D signal constellation that has a power efficiency (and sensitivity) advantage over polarization-division multiplexed QPSK (PDM-QPSK). Using a polarization-rotated form of PS-QPSK, we show that it is equivalent to a short block code, and assert that basic information theory explains its advantage over PDM-QPSK. We consider the practicality of PS-QPSK by considering its performance after a forward error correction (FEC) is applied, as this is the true measure of a modulation format's power efficiency. When fairly compared with the same data rate, bandwidth, and transmit power, simulations show that PS-QPSK is actually not as efficient as PDM-QPSK when a sufficient FEC is applied to achieve the very low BERs required in practice.
ISSN:1041-1135
1941-0174
DOI:10.1109/LPT.2011.2174978