Generic error control coding modules

Abstract

The design and test of error control encoding and decoding mod ules for simulating data communications systems is described. Generic application library modules for the Interactive Commu nications Systems Simulation Module (ICSSM) were developed for block and convolutional codes using the programming lan guage FORTRAN. The end user specifies a system for simulation study by linking various communications, signal processing and error control modules.

In developing the encoding and decoding modules, a top-down approach resulted in a heirarchy of subroutines and function calls. This approach simplified the validation task and allowed easier upgrades and maintenance. Some of the design trade-offs for both the block code and convolutional code modules are viewed. It was found that modest use of storage can be traded for execution time. Various computations and operations can be efficiently accomplished with table look-up when using a high-level language such as FORTRAN.

A simple communication system using these modules was studied. The error behavior was as expected. The key problems identified in this development were systems issues; primarily, module initialization and synchronization.