A Modified Unquantized Fano Sequential Decoding Algorithm for Rateless Spinal Codes

A modified unquantized Fano sequential decoding (MUFSD) algorithm for rateless spinal codes is proposed. The maximum storage space is introduced in MUFSD algorithm. When the number of stored nodes exceeds the storage space, the decoding is stopped immediately so that the decoding process can be controlled well. The calculated nodes are reserved at each forward calculation which reduces the computational complexity. An expression of the new branch metrics of spinal codes over additive white Gaussian noise (AWGN) channel are derived for the MUFSD algorithm. Simulation results show that the complexity and time consumption of the MUFSD algorithm for spinal codes are further reduced without sacrificing the rate performance compared with those of the bubble decoder and the forward stack decoding (FSD) algorithm. Particularly, in the case of low signal-to-noise ratio (SNR), the complexity and time consumption of the MUFSD algorithm are significantly decreased.