Research and realization of RS codec based on FPGA technique

Abstract

According to the problem that the laser signal will produce serious distortion and BER increases affected by influences of the space channel environment including atmospheric turbulence, refraction and so on, the forward error correction (FEC) technique is adopted. Meanwhile, technologies for the laser communication system such as encode, interleaving, decode have been discussed in details. RS code is applied in this system and RS (255,223) code is selected as channel code. It reduces system's signal-to-noise ratio (SNR). In this paper, an improved RiBM algorithm is adopted in the key equations solver of decoding algorithm and the galois field multiplier is designed based on composite basis. Then, division operation in the error value is realization by subtraction of power exponent. Algorithms program have been finished on FPGA. As a result, the whole decoding chip obtains the optimization in the speed and the usage resources. Based on this encoding and decoding algorithm, relationship between interleaving depth and error-correcting ability is simulated by Matlab. Results show that error-correcting capability increases 2 order magnitudes when interleaving technique is used to noise bursts channels.