A simple metric for ad hoc network adaptation

This paper examines flexibility in ad hoc networks and suggests that, even with cross-layer design as a mechanism to improve adaptation, a fundamental limitation exists in the ability of a single optimization function, defined a priori, to adapt the network to meet all quality-of-service requirements. Thus, code implementing multiple algorithms will have to be positioned within the network. Active networking and programmable networking enable unprecedented autonomy and flexibility for ad hoc communication networks. However, in order to best leverage the results of active and programmable networking, metrics that indicate the nature and location of required flexibility need to be developed. The primary contribution of this paper is to propose a metric that couples network topological rate of change with the ability of a generic service to move itself to an optimal location in concert with the changing network. This metric points to a fundamental tradeoff among adaptation (changing service location), performance (sophistication or estimated minimum code size of the service), and the network's ability to tune itself to a changing ad hoc network topology.