Advanced Teleprocessing Systems Defense Advanced Research Projects Agency

摘要

Under our first task, distributed communications access, we conducted an indepth research effort in evaluating the performance of packet radio systems in a variety of environments. We pushed the analytic side of this field to its point of diminishing returns and found that we had reached a barrier beyond which the analytic payoff will be meager and the analytic effort would be enormous. We have determined a number of key principles and properties of multi-hop packet radio networks and have reported upon these in our publications. The problem of a complete analysis of multi-hop packet radio systems was found to be intractable and, therefore, we phased out that portion of the research half way through this contract. We devoted much of our effort to the final two tasks, namely, distributed processing and distributed control and algorithms. Here, we have launched into uncharted terrain in an attempt to uncover the proper models with would expose the important principles of Distributed Systems. Our efforts here have been rewarded with some important successes. We have studied distributed algorithms in networks involving such functions as elections and traversal. Local area networks has been an object of our study and here, the introduction of a broadcast communications environment has provided the motivation for some rather extensive evaluation of broadcast communications. We have found there are some important advantages of broadcast communications in a number of these environments.