Performance of Modified-Fano Algorithm in Adaptive-Variable-Rate Transmission System over Fading Channels

Abstract

Ideas of feedback, adaptive transmission and coding have been combined to improve the performance of communication systems over the Rayleigh fading channel with slow and flat fading assumption. The coded variable-rate transmission systems employ the Fano and the modified Fano algorithms for decoding [1]. The simulation study of the uncoded variable-rate bipolar signalling with continuous rate adaptation over an infinite range shows that such a system can completely nullify the effect of fading. A four-rate uncoded systems is only 0.5 dB inferior and the two-rate coded system with either Modified-Fano or Fano decoding is only 0.4 dB inferior to the ideal infinite rate systems at a BER of 10-⁵. The increase in the average rate of transmission of both coded and uncoded variable rate systems is found to degrade the error performance. For the coded systems both the Fano and Modified-Fano algorithms provide the similar error performance but the Modified-Fano decoder provides the throughput advantage over the Fano decoder.

Indexing terms:

• Sequential decoding
• Adaptive transmission
• Fading channels