Accession Number:

ADA159192

Title:

Adaptive Combining Applied to Noisy Networks.

Descriptive Note:

Final rept.

Corporate Author:

CNR INC NEEDHAM MA

Personal Author(s):

Report Date:

1985-08-05

Pagination or Media Count:

91.0

Abstract:

This reports purpose is two-fold first to present an in-depth study of code combining using both analytical and empirical methods and secondly to evaluate its effectiveness in various communication scenarios, particularly its use in ARQ systems. On very noisy channels, code combining allows significant throughput where other coding techniques fail. It can also be used to adaptively optimize the code rate on unknown or varying channels. Finally these features can be provided by incorporating code combining into existing communication schemes such as ARQ. Code combining is a technique for combining any number of repeated packets encoded with a rate-R code to obtain a lower rate, and thus more powerful, error-correcting code. The conclusions of this report are that we have 1 Derived and applied analytic expressions describing the performance of code combining 2 Developed a decoding algorithm which simplifies the implementation of a maximum-likelihood code combiner 3 Proposed and analyzed new techniques for using code combining including relaying of undecoded packets, early decoding of header information and production of rate-1N codes and 4 Established the performance of code combining in both ideal and practical selective-repeat ARQ systems. Together these results constitute a significant contribution to the understanding and application of code combining.

Subject Categories:

  • Theoretical Mathematics
  • Cybernetics
  • Non-Radio Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE