| In ad-hoc network where available bandwidth is limited, the amount of transmitted data needs to be reduced. Especially in tactical ad-hoc networks, the bandwidth constraints are much severer than in commercial or general public networks. In order to decrease the data amount, flexibility of the transmitted information should be limited. In usual information theory, the basic criterion for effectiveness of coding is entropy based on probability. In this paper, we propose a new measure, urgency index and urgency entropy, to evaluate the effectiveness of coding, in urgent communication.
In addition to decreasing the total amount of data, one can increase the total amount of user satisfaction by appropriately incorporating a wide variety of services. In order to describe the user satisfaction and characteristics of applications, concepts of utility function and elasticity have been used. Traditional delay tolerant data applications such as file transfer are called elastic, and delay sensitive applications such as telephony are called inelastic. The elasticity is described as function of the utility function and the communication resource. Evaluation measure of the elasticity, however, has not been discussed much. In this paper, we propose local elasticity as an application of urgency index, to quantitatively evaluate the elasticity, and entropy of the local elasticities.
The paper is organized as follows. After the introduction, we first summarize the issues in bandwidth constrained, control-based tactical ad-hoc networks. We also review the concept of a utility function and elasticity. We then propose our new metric in comparison with the conventional information theory parameters. We then show the application of the proposed schemes for bandwidth constrained, tactical ad-hoc network design, using utility functions and elasticity.
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| Haruko Kawahigashi received the B.E. and D.Eng. degrees in electrical engineering from the University of Tokyo, in 1985 and 2001, respectively. She joined Mitsubishi Electric Corporation in 1985, where she has been engaged in the development of high-speed multiplexers and in research on teletraffic control, neural network and path planning. From 1991 to 1992, she was a visiting scholar at the University of California, Berkeley. She is currently a chief researcher of Information Technology R & D Center of Mitsubishi Electric Corp.. Her current research interests include network design of wireless and tactical ad-hoc networks. She is a senior member of IEEE, and a member of IEICE and the Operations Research Society of Japan. |