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Phase modulation has been widely used in the 40G system

Phase modulation has been widely used in the 40G system, which further Panasonic laptop battery promoted the maturity of this technology in the 100G. Laptop battery using the QPSK technology can make double the amount of information carried by the optical carrier increases, combined with polarization multiplexing makes the 100G signal baud rate is reduced to about 25Gbaud / s, can be used in the 50GHz interval OTN system, but also reduces the signal on the fiber nonlinearity tolerance.the FEC super-coherent detection, DSP technology innovation, is the development of technology and change, 100G only truly usher in a commercial era.

FEC is one of the most critical 100G technology, the FEC will receive a variety of system performance. 40G transmission system following which, Samsung laptop battery more than 7% overhead hard-decision FEC take BCH cascade or the design of the BCH and RS Concatenated coding gain to a maximum of about 9dB, in theory, 7% overhead FEC coding gain limit is 10dB. Low Density Parity Check (LDPC) code due to the longer length of coding at the same time check matrix with the sparsity of laptop battery apart distant symbol checksum at the same time, contribute to the continuous burst error discretization, so LDPC effective in correcting a burst error of longer.

In addition, LDPC iterative algorithm for decoding, Sony laptop battery the decoding circuit can realize the parallel processing, in order to have low complexity and delay of small advantages. OIF recommended LDPC 100G mainstream of one of the FEC code type. Soft decision is also another effective way to improve the coding gain. Traditional hard decision signal quantization bit, non-"0", "1" soft-decision with multiple bits (taking into account the design complexity, usually bits 5) and to quantify the signal, and then estimated by the Viterbi algorithm to improve judgment accuracy. Toshiba laptop battery Soft-decision coding gain than hard decision can be higher than 1dB.