Communications overhead as the cost of constraints

This paper speculates on a perspective for studying overhead in communication systems that contrasts the traditional viewpoint that overhead is the "non-data" portion of transmissions. By viewing overhead as the cost of constraints imposed on a system, information-theoretic techniques can be used to obtain fundamental limits on overhead information, and multiple constraints lead to an intriguing chain rule for overhead. In principle, protocol overhead in practical implementations can then be benchmarked against these fundamental limits in order to identify opportunities for improvement. Several examples are discussed within this developing framework.