Simulation and visualization of the Viterbi decoder using a spreadsheet

This paper demonstrates that a spreadsheet is an excellent tool for the simulation of the Viterbi decoder for educational purposes. Spreadsheet programming is streamlined by using complex number representations for metrics computation, allowing two values associated with each state at each time to be stored in a cell, thus providing a one-to-one correspondence between the spreadsheet cells and the nodes in the trellis diagram. The decoded path is plotted in a trellis diagram on the same spreadsheet so that the results can be readily visualized and examined. Either soft-decision or hard-decision decoding can be performed. A simple convolutional code of rate 1/2 and constraint length 3 is used for illustration, but the spreadsheet program is structured in such a way that it can be readily modified to simulate other codes.