Performance Analysis of sub interleaver for turbo coded OFDM system

4G LTE / 5G is the high speed communication system developed for smart phones and other mobile devices in the recent era. The current level of mobile device usage and data exchange over the internet has raised the need for such a fast and secure communication system. One of the important feature in an LTE system is the use of OFDM technique, owing to its advantage namely robustness to multipath fading and interference. This paper proposes an improved OFDM based 4G LTE system fused with turbo code encoding technique to further reduce the bit error rate over noisy real-time channels. The proposed turbo codes system has a hybrid two stage interleaver which is a combination of 3GP interleaver and block interleaver. This interleaver reduces the time required for interleaving processing while maintaining the BER criteria up to the levels. The traditional decoder has been replaced with a threshold-log-MAP algorithm based interleaver for improved noise tolerance. The proposed system has been tested over various channels like Rayleigh, rician and nakagami channels. The experimental results prove that the performance of the stem has improved in comparison by the addition of turbo codes.