FEC, AFEC, and super modules


FEC and AFEC are different encoding formats. The difference between the super board and non-super board lies in modulation formats. The AFEC and super modules are designed for adding the transmission distance of WDM equipment without regeneration. The following combinations are available:
Common FEC
Common FEC + Super module
AFEC +Super module
Signals of different modulation formats can be interconnected, while signals of different encoding formats cannot be interconnected. That is, OTU boards with and without the super module can be interconnected, but OTU boards of the AFEC and FEC encoding formats cannot be interconnected.

Other related questions:
Threshold of the pre-FEC BER that will trigger post-FEC bit errors on LWF boards using the FEC/AFEC function in BWS 1600G devices
When the pre-FEC BER reaches 10E-7, the system will start bit error processing. (The actual error correction limit of Huawei WDM devices can reach around 10E-5 for G.975-compliant FEC, and reach around 10E-3 to 10E-4 for AFEC.)

FEC threshold
In general, there are thresholds for the pre-FEC and post-FEC bit errors. Pre-FEC bit errors are affected by many factors and can be ignored. After error correction, however, ensure that there are no bit errors. That is, the threshold for post-FEC bit errors must be 0.

Value of pre-FEC BER of the LWF board in FEC or AFEC mode on WDM 1600G devices that causes post-FEC BER
When the pre-FEC BER reaches 10E�?, the bit error handling will be initiated. The error correction threshold of Huawei WDM devices can reach around 10E�? for FEC which meets the G.975 protocol standards, and reach around 10E�? to 10E�? for AFEC.

Interconnection and differences between FEC and AFEC on WDM equipment
AFEC is an enhanced forward error correction function, but FEC is a standard error correction function. The frame structures of the two functions are different and therefore cannot be interconnected.

Permitted maximum pre-FEC BER of the FEC function
Theoretically, the maximum pre-FEC BER permitted by the FEC function for the OTU board is 8.27E-5.

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