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.

Other related questions:
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 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.

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 encoding supported by Huawei WDM equipment
Huawei WDM products provide the forward error correction (FEC), high performance forward error correction (HFEC), soft-decision forward error correction (SDFEC), and advanced forward error correction (AFEC) functions on different OTU, tributary, and line boards. The FEC, HFEC, SDFEC, and AFEC functions help decrease the OSNR requirements of the system at the receive end and extend the transmission distance between optical amplifier sections and regenerator sections. In addition, the FEC, HFEC, SDFEC, and AFEC functions help reduce bit error rate during line transmission and enhance the transmission quality of DWDM networks. Note that boards that use different FEC modes cannot interconnect with each other.

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.

Difference between conventional WDM equipment and OTN equipment
Both of them use the DWDM technology. The difference between them lies in that OTN equipment can achieve electrical cross-connection scheduling for various types of services.

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