Analysis Of Digital Signals In Microwave Communication Technology And Systems

Nowadays,digital communication systems are in common use and generally carry the bulk of our daily information transmission through different communication media such as wire line channels,microwave radio,fiber optic channels and satellite channels.Digital transmission is not free from channel losses such as noise,interference and fading which effect signal distortion and degradation in signal to noise ratio.These introduce many errors on the information bits sent from one place to another place.To fix these problems,it has become necessary to give better and efficient service to users using better techniques.This thesis project presents Graphical User Interface(GUI)for simulating Convolutional coding with Viterbi decoding in AWGN channel.Convolutional coding is introduced at the transmitter and Viterbi decoding at the receiver to guarantee reliability of error free transmission.The encoding process was demonstrated using a(2,1,3)convolutional encoder and the decoding process was presented also using a hard decision Viterbi decoder and a soft decision Viterbi decoder with BPSK modulation.In order to visualize the effect and evaluate the performance of coding,decoding and modulation used;simulation programs that encode and decode digital data were designed,written and tested in MATLAB.The bit error rate(BER)is plotted against energy per bit to noise spectral density(Eb/No)for different digital input data.It is seen that as increasing Eb/No reduces the bit error rate of the signal thus introduces less error in the transmission systems.Simulation results shows that the soft Viterbi decoding performs better than the Hard Viterbi decoding for decoding information bits coded by a convolutional encoder and therefore the performance of convolutional coding with Viterbi decoding was really improved by the smaller code rate used.Additional analysis and discussion were made on the MATLAB graph results obtained.