Title :
Flexible transponder design aided by agile binary bit encoder
Author :
Shaoliang Zhang ; Yaman, Fatih ; Ting Wang
Author_Institution :
NEC Labs. America, Inc., Princeton, NJ, USA
Abstract :
In order to accommodate variable bit rates and achieve flexible transmission distances, a binary bit encoding scheme is incorporated in the dual-polarization (DP) quadrature phase-shift keying (QPSK) transmitter to manipulate the signal polarization multiplexing schemes into polarization-multiplexed (PolMux), polarization-switched (PolSw), and polarization-alternated (PolAl) schemes, such that the transmission bit rate could vary among 4B, 3B, and 2B, where B stands for the baud rate of the DP-QPSK signal. With the versatile polarization schemes, the trade-off between the transmission performance and system bit rate could be flexibly adjusted depending on the system requirements and conditions. The performance of these modulation formats has been evaluated experimentally at 32 Gbaud in a dispersion-managed fiber (DMF) link. At a 0.5 dB system margin, the transmission reach of PolSw and PolAl QPSK increased to ~6400 and ~8500 km, respectively, compared to the ~4500 km transmission distance using the PolMux QPSK signal. This improvement is attributed to the lower bit rate of PolSw QPSK (96 Gbits/s) and PolAl QPSK (64 Gbits/s) and to the superior characteristics of the PolSw and PolAl schemes. For example, PolAl QPSK performs as good as the PolMux BPSK format to show similar receiver sensitivity. At the end, a flexible transponder platform with full software-defined optics features is discussed using the proposed flexible transmitter configuration and other techniques, such as optical multi-tone generation and adaptive forward error correction, to enable the transponder to carry standard 10G/40G/100G data.
Keywords :
binary codes; forward error correction; multiplexing; optical fibre communication; optical fibre dispersion; optical fibre polarisation; optical transmitters; quadrature phase shift keying; transponders; DP-QPSK signal; PolMux QPSK signal; adaptive forward error correction; agile binary bit encoder; baud rate; binary bit encoding scheme; dispersion-managed fiber link; dual-polarization quadrature phase-shift keying transmitter; flexible transmission distances; flexible transmitter configuration; flexible transponder design; full software-defined optics features; modulation formats; optical multitone generation; polarization-alternated scheme; polarization-multiplexed scheme; polarization-switched scheme; receiver sensitivity; signal polarization multiplexing schemes; system bit rate; system conditions; system requirements; transmission bit rate; transmission performance; variable bit rates; versatile polarization schemes; Binary phase shift keying; Bit rate; Optical transmitters; Q-factor; Transponders; BPSK (binary phase-shift keying); Bit encoder; Modulation format; Polarization multiplexing; QPSK (quadrature phase-shift keying); Software-defined transmitter; Variable bit rate;
Journal_Title :
Optical Communications and Networking, IEEE/OSA Journal of
DOI :
10.1364/JOCN.5.000722