Abstract:

In order to improve the encoding efficiency of repeat accumulate codes under the circumstance of long input information, we present an optimized interleaver design for repeat accumulate codes. The input information sequence of interleaver is regrouped by the child nodes of full binary tree according to its parity arrangement, and the output sequence is obtained by using the leaf nodes to recombine the grouped sequence. Therefore, the relativity among input information is greatly reduced compared with S-random interleaver, and it prevents the class-I and classII four circles of check matrix from being produced in the encoding process while the decoding accuracy is guaranteed. Simulation results show that the optimized interleaver is faster and its BER is far less than regular interleavers under long input information; and the optimized interleaver is much faster and has a better performance(about 0.3 dB) than S-random interleavers at the same BER of 1*10-4.

Key words: full binary tree;interleaver;repeat accumulate code;check matrix;S-random interleaver