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Game theory is a set of tools developed to model interactions between agents with conflicting interests, and is thus well-suited to address some problems in communications systems. In this paper we present some of the basic concepts of game theory and show why it is an appropriate tool for analyzing some communication problems and providing insights into how communication systems should be designed. We then provided a detailed example in which game theory is applied to the power control problem in a CDMA-like system.

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This paper presents a definition and framework for a novel type of adaptive data network: the cognitive network. In a cognitive network, the collection of elements that make up the network observes network conditions and then, using prior knowledge gained from previous interactions with the network, plans, decides and acts on this information. Cognitive networks are different from other "intelligent" communication technologies because these actions are taken with respect to the end-to-end goals of a data flow. In addition to the cognitive aspects of the network, a specification language is needed to translate the user's end-to-end goals into a form understandable by the cognitive process. The cognitive network also depends on a Software Adaptable Network that has both an external interface accessible to the cognitive network and network status sensors. These devices are used to provide control and feedback. The paper concludes by presenting a simple case study to illustrate a cognitive network and its framework.

Abstract-Aloha is perhaps the simplest and most-studied medium access control protocol in existence. Only in the recent past, however, have researchers begun to study the performance of Aloha in the presence of selfish users. In this paper, we present a game-theoretic model of multipacket slotted Aloha with perfect information. We show that this model must have an equilibrium and we characterize this equilibrium. Using the tools of stochastic processes, we then establish the equilibrium stability region for some well-known channel models.

Past studies of Aloha have emphasized system-wide goals such as achieving maximum throughput or minimum delay. In this paper, we use game theory to analyze Aloha from the perspective of a selfish user. We construct an Aloha game and examine the optimal behavior of individual users. We show that the Aloha game has an equilibrium and that an Aloha system in which the users are selfish will be stable provided the attempt rate is sufficiently low. We then compare the performance of a selfish Aloha system with the performance of a centrally-controlled slotted Aloha system. With some system parameters performance is near the optimum performance obtained by a centrally-controlled system. By utilizing a selfish-user assumption, it is possible to build systems which are robust and scalable.

Game theory provides a wealth of tools that can be applied to the design and operation of communications systems. In this article, we provide a brief introduction to game theory. We then present applications of game theory to problems in random access and power control. In the case of random access, we examine the behavior of selfish users in a simplified Aloha system; surprisingly, rational selfish users do not implement the "always transmit" strategy that one might expect. In the case of power control, we show that game theoretic techniques can yield an optimal operating point without the intervention of an external controller.