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Detail
Journal Article
C-band PAM-4 Signal Transmission using Soft-output MLSE and LDPC Code
- Authors
- S.-R. MOON, H.-S. KANG, H. Y. RHA, J. K. LEE
- Issue Date
- 2019-01
- Citation
- Optics Express, v.27 no.1, pp.1-11
- ISSN
- 1094-4087
- Publisher
- Optical Society of America (OSA)
- Language
- English
- Type
- Journal Article
- Project Code
- 18HH1200, Development of 200Gb/s optical transceiver for metro-access network, Lee Joon Ki
- Abstract
- We propose a DSP scheme with soft-output maximum likelihood sequence equalizer (sMLSE) and low-overhead (8.51%) low density parity check (LDPC) code for C-band PAM-4 transmission. In order to apply LDPC code in conjunction with MLSE, the conventional hard-output MLSE is modified to have a soft-output value by using the Max-log BCJR algorithm. The feasibility of this approach is experimentally investigated in a 56 Gb/s C-band PAM-4 system. In order to investigate the advantages of the proposed scheme, we compare the performance of the sMLSE-LDPC code to that of MLSE-RS code. Relatively, additional OSNR gain of 0.6 dB ~2.1 dB is achieved. The variation of the relative OSNR gain depends on the burst errors, which originate from the power fading effect. By using an interleaver that spreads burst errors in time, one can see that the relative OSNR gain is improved as 1.6 dB ~2.1 dB. Using the proposed scheme with the interleaver, one can see that the 30 km transmission of 56 Gb/s PAM-4 in the C-band was experimentally demonstrated.
- KSP Keywords
- 4-level pulse amplitude modulation(PAM-4), BCJR algorithm, C-band, Fading effect, Low density parity check (LDPC) code, RS code, Signal transmission, Soft-output, burst errors, low overhead, maximum likelihood