130x1g2 - CCSDS

TM SYNCHRONIZATION AND CHANNEL CODING—SUMMARY OF CONCEPT AND RATIONALEbased communications systems, BER is more commonly shown for existing codes and isincluded here for ease of comparison.Figure 8-8: Bit Error Rate (Solid) and Frame Error Rate (Dashed) for Nine AR4JACodes and C2, with Code Rates 1/2 (Red), 2/3 (Green), 4/5 (Blue), and 7/8(Black); and Block Lengths k=16384, 4096, 1024 (Left to Right in EachGroup), and 7156 (Code C2).8.7 IMPROVING PERFORMANCE IN THE ERROR FLOOR REGIONWhen using common LDPC decoders with standard check node processing, the appearanceof an error floor effect may occur for some of the recommended AR4JA LDPC codes.In particular, the rate 2/3 AR4JA code with k=1024 information bits and, in a more markedmanner, the rate 4/5 AR4JA code with k=1024 information bits may exhibit a slopeflattening at a FER on the order of 10 -6 .This effect can be compensated by optimizing the LDPC decoding algorithm. In particular,the decoder should (reference [54]):CCSDS 130.1-G-2 Page 8-10 November 2012