In‐band coding technique to promptly enhance SDH/SONET fiber‐optic channels with FEC capabilities

Abstract

SUMMARYIn the present paper, we discuss FEC-methods for SDH/SONET networks under the perspective of DWDM. The lightwave channels are assumed to have a burst-error character. First, a FEC-strategy is outlined by means of fundamental performance criteria. The SDH/SONET frame-overhead is also explored for possible allocation of error-correction bits inside. Then, different FEC methods are rated by the above criteria in a systematic manner. We eventually propose a section-and line-layer, in-band coding (IBC) approach that should deal with a very wide range of optical network applications in a straightforward, uniform and effective fashion. Comparison with past work on this subject reveals clear advantages. Extensive simulations, implementation and laboratory measurements prove the feasibility and efficiency of the proposed FEC method with RS(244,240,9), provided that a portion of the SDH/SONET overhead is available.

Optimization of the "FOCUS" Inband-FEC Architecture for 10-Gbps SDH/SONET Optical Communication Channels

“…In return, the degree of all polynomials involved in FOCUS decoding is halved and the overall complexity is halved as well. This trade-off gives rise to the so-called 'weak'-mode of FOCUS operation [2], [3].…”

“…The 1 st stage is a usual polynomial multiplication over GF (2) between the operands of GF-mult (treated here as polynomials with bit-coefficients). With FOCUS operating over GF (2 9 ), operands are 9-bit wide and the output product is 17-bits wide.…”

“…row-triplet No 3). At point [2], the syndrome-values are available to the 2 nd step (L) for the formation of λ(x). Label [3] points at the beginning of the 3 rd step (C) during which all necessary corrections are applied.…”

“…FOCUS has been modelled in VHDL and implemented in a large Xilinx® Virtex-II™ FPGA (XC2V-3000-4), situated on '10g-Tester', a PCB card designed for operation in excess of 10Gb/s [2]. At the transmitting card, an Intel® LXT16717 MUX is used to serialize the SDH frames, while at the receiving card an Intel® LXT16716 DEMUX parallelizes the frames again to allow for bulk processing at lower speed.…”

“…The proposed iFEC method, FOCUS, was initially introduced in [2]. It applies to the Regenerator (RS) and Multiplex-Section (MS) functionality of SDH (equally, SONET), utilising the shortened Reed-Solomon code RS(244,240) operating over Galois-Field GF (2 9 ).…”