Performance Improvement of 7200 bps IMBE Vocoder with Improved FEC

APCO Project 25 (P25) digital radios became widespread for either government or personal communication in the last two decades. Since the P25 standards are quite old, performance of its voice services is not satisfactory when compared to today's standards. Although 7200 bps Improved Multi-band Excitation vocoder used in P25 incorporates a decent rate of forward error correction, it does not provide fine error correction for noisy communication channels. In order to improve performance of P25 radios, we proposed a better forward error correction scheme which consists of 11/18 punctured convolutional coder and Viterbi decoder. The proposed forward error correction scheme provides 4.82 dB coding gain hence increases the performance of P25 radios.