Real-time determination of tactical information requirements

All tactical digital communications architectures include provisions for error detection and correction (EDAC), and for repeating, relaying, and updating messages. In addition, the most important messages generally require receipt/compliance replies, to ensure that if the message is lost it will be repeated immediately and as often as necessary to ensure receipt. These features are collectively referred to as redundancy, and are built into the message standard for the links involved. Purposeful redundancy in message standards reflects an awareness on the part of the link designers of concepts of information theory. However, those information-theoretic components are rarely formalized, and in any case message standards do not provide adaptive, real-time analysis of information requirements. The issue addressed in this paper is how to measure the information content of tactical data, so as to determine the optimal update/repetition rate for messages, or the optimal data screening for overloaded processes. After a brief review of the relevant concepts of information theory, we describe a real time metric for measuring information in tactical operations, and show how to apply that metric to a common tactical scenario, in which a sensing unit reports track positions to a remote tracker over a surveillance net. We conclude with some ideas on extending this approach to filter messages based on estimates of their probable effect on the recipients.