Fast turbo codes using sub-block based interleaver

Abstract

Information theory provides fundamental benchmarks based on which different communication systems can be compared. Given the channel model and transmission constraints, the information theory enables to compute rate at which reliable communication is possible. Once this rate or in other words the channel capacity is calculated, it is the task of system engineer to devise coding schemes that approach this capacity. Though the Shannon theory appears to be computationally feasible, still it was not practically implementable. The invention of turbo codes was established as an approach of reaching close to Shannon limit. The performance of turbo code depends largely on the design of interleaver. The bit error rate and delay incurred in encoding and decoding are highly influenced by the interleaver. In this paper, sub-blocking based interleaver architecture is proposed which can be extended to any existing interleaver structure. The advantage of sub-blocking the input frames is that the complexity of the interleaver reduces and consequently the execution time will be reduced drastically. In addition, a simultaneous processing of interleaving and de-interleaving can be achieved. In this paper, the said architecture is verified for block and 3GPP interleavers with different combinations. It is shown that a reasonable BER is achieved in very less time compared to all existing interleavers.