A Robust Real-Time 100G Transceiver With Soft-Decision Forward Error Correction [Invited]

Abstract

We demonstrate a 120 Gb/s coherent polarizationmultiplexed quadrature-phase-shift-keyed transceiver with soft-decision forward-error-correction (SD-FEC) coding based on Turbo Product Code. This industry-first transceiver module utilizes a 40 nm complementary metal-oxide semiconductor (CMOS) application-specific integrated circuit with integrated analog-to-digital conversion, digital signal processing and SD-FEC, and is packaged according to a multi-source agreement from the Optical Internetworking Forum. Through several long-haul and ultra-long-haul system experiments (over 1000 km to 3760 km), we validate the robustness of the transceiver and demonstrate its high tolerance to various system impairments, including fiber nonlinearity, chromatic dispersion up to 60,000 ps/nm, polarization mode dispersion, polarization-dependent loss, polarization transients and multiple-path interference.

Hybrid optical CDMA-FSO communications network under spatially correlated gamma-gamma scintillation

“…Nevertheless, all simultaneous users can still obtain error-free transmissions (ABER ≤ 10 −12 ) as long as FEC (with only 7 % of overhead) [41] is employed under a SNR as low as -1 dB. Eventually, an ABER limit of 3.8 × 10 −3 [41] for hard decision (see horizontal dotted line in Fig. 6) should be adopted to implement this FEC algorithm, thus representing the error-free transmission limit.…”

A configurable FPGA FEC unit for Tb/s optical communication

“…For small values of p, this converges towards the PFL from (3). The post-FEC BER of the error floor may be estimated using (9)   An error floor analysis is also found in [17], but with assumption of an ideal bounded distance decoder for the BCH code. The code used in the experiment is shortened a little to n = 1008, but it is believed that the above expressions are still approximately valid.…”

“…For modulation systems of higher order than QPSK, soft decisions may be used to reflect the different reliabilities of the received bits. Soft decisions may be a feasible solution in integrated ASIC design, [9]. Several hard-decision FEC codecs have been proposed for 100 Gb/s, all having a NCG around 9 dB with an overhead slightly less than 7%, e.g.…”

Low-Complexity Time Synchronization Algorithm for Optical OFDM PON System Using a Directly Modulated DFB Laser

“…As the hardware cost of digital signal processing has a strong dependence with the number of quantization bits, these low values allow us to obtain a low cost hardware implementation. We have taken the BER value of 10 −2 as a reference because it is commonly considered a forward error correction (FEC) threshold to obtain an error free transmission when a soft decision FEC coding with 20% redundancy is employed [16]; on the other hand, in case a hard decision FEC coding with 7% redundancy were employed, the FEC threshold would be 3.8 × 10 −3 [17], which corresponds with a SNR of 4.9 dB.…”