Performance of forward error correction coding in the presence of in-band crosstalk

Our measurement results clearly show that 7% Reed-Solomon coding can handle large levels of in-band crosstalk. However, there is also clear evidence that behavior of the FEC coding departs from the normal under the extreme cases. The performance of direct detection receiver and an optically preamplified receiver are different when looked at from the sensitivity point of view, but similar when looked at from the output-input BER point of view. Incidentally, measurements made with the optically preamplified receiver with FEC coding enabled and no crosstalk present indicated one can approach quantum-noise limited sensitivity. The randomness of noise is essentially reduced and tends towards being deterministic under FEC coding.