ABSTRACT

This research focuses on modeling of convolutional encoder with Viterbi decoder for next generation broadband wireless access systems. A stipulated rate-compactible punctured convolutional codes from the usual mother rate 1/2, constraint length K = 7 and generator used in the Simulation of the model which was carried out over an Additive .White Gaussian Noise (AWGN) channel using the Binary Phase Shift Keying (BPSK) modulation technique. When soft decision coding with Configurable Rates of !6 and 2/3, input random sequence of 1 million bits for a range of 0 - 14dB was simulated. It was observed that BER for each quantization width decreased exponentially with the increase in SNR. The coding gain of each of them at 0.14 BER showed some slight differences with the 4-bit quantization, though not I? it was seen that an increase in the coding rate of £k/n’ resulted in a decrease in SNR gain ofboth. Also soft decision coding with width of 2 tends to have a better coding gain as compared to soft Viterbi decoder to decode the normal 1/n code rate with K constraint length, a trace-back comparison is made with a Viterbi decoder with an infinite memory. xiii decision coding with width of 3. These established benefits both the increase in SNR (Eb/No) and coding rates. Also, observations have proved that in using length of ‘Kx5’ or ‘Kx6’ will be fully enough for the Viterbi decoder to comfortably handle the received data symbol decoding without any noticeable performance degradation as against when width. Comparing soft decision coding with width of 2 and soft decision coding with width of 3, polynomial 1171. 133] was employed to obtain higher rate of 2/3.