Study of Error Control Coding for the U.S. Postal Service Electronic Message System,

摘要

A U.S. Postal Service (USPS) electronic message system could incorporate many types of error control coding,or no coding at all. This report reviews a variety of possible codes,lists their advantages and disadvantages,and selects a preferred alternative. It turns out to be a concatenation of an inner convolutional (rate 1/2to rate 3/4) code with Viterbi decoding,and an outer long block,high efficiency code. The two codes have separate functions,in the sense that the inner code performs forward error correction and the outer code does error detection only. The report describes the structures,properties,and implementations of the coding hybrid. After that,the performance of the preferred coding scheme is estimated. The resultant error probability gains,which are shown to be considerable,are balanced against system slowdown and bandwidth expansion.