Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...
Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...
Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...
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Towards Adaptive WLAN Frequency Management Us<strong>in</strong>g Intelligent Agents 119ronment <strong>in</strong> a useful manner [11]. An <strong>in</strong>telligent agent exhibits the follow<strong>in</strong>g properties:autonomy - the agent is capable of follow<strong>in</strong>g its goal autonomously that is, without<strong>in</strong>teractions or commands from the environment - reactivity - the agent is capableof react<strong>in</strong>g appropriately to <strong>in</strong>fluences or <strong>in</strong>formation from its environment - proactivity- under specific circumstances, the agent can take the <strong>in</strong>itiative <strong>in</strong> perform<strong>in</strong>gappropriate actions - social ability - the agent is able to communicate with otheragents and to <strong>in</strong>teract with its environment <strong>in</strong> order to fulfill its tasks.Intelligent agents have been considered for network management <strong>in</strong> numerous researchprojects 3 . These various projects have led to multi-layer agent architectures <strong>in</strong>which each layer implements different abstraction views; examples of such layers arethe co-operation layer, the plann<strong>in</strong>g layer and the reactive layer. In this context, theBelief-Desire-Intention [12] probably constitutes one of the most popular agent architectureand has also been considered, under different forms, <strong>in</strong> agent-based networkmanagement systems.The development of agent standards <strong>in</strong> telecommunication is obviously a s<strong>in</strong>e quanon condition for the successful deployment of software agents <strong>in</strong> large-scale networks.The most popular agent standard at the moment is the Foundation for IntelligentPhysical Agents (FIPA) 4 .The framework we propose <strong>in</strong> this paper consists of a simple architecture <strong>in</strong> whichwe ma<strong>in</strong>ly exploit the message and communication facilities provided <strong>by</strong> the agentplatform on the one hand, and the capability of an agent to implement different parallelbehaviors on the other hand. Details about agent behavior are given <strong>in</strong> Section 3.2.Our agent-based framework is therefore composed of <strong>in</strong>telligent agents, calledAWM_agents, which exchange <strong>in</strong>formation concern<strong>in</strong>g their local environment <strong>in</strong>order to perform on-l<strong>in</strong>e optimization <strong>by</strong> (re-)configur<strong>in</strong>g the access po<strong>in</strong>t frequency(or channel). The enhanced access po<strong>in</strong>t consequently exhibits an autonomous andadaptive behavior.3.1 Jade and LEAP Agent PlatformsJade 5 is a freely downloadable Java agent platform, which is fully compliant with thelast revision of FIPA specifications; the <strong>in</strong>tra-agent activity model def<strong>in</strong>ed <strong>in</strong> Jade isbased upon a non-pre-emptive concurrency model. A Jade agent is implemented witha Java thread, which enables asynchronous <strong>in</strong>ter-platform communication as specified<strong>by</strong> FIPA. The Jade agents can implement one or several behaviors: while <strong>in</strong>tra-agentactivities are synchronous, <strong>in</strong>ter-agent communication relies on an asynchronousprocess. The behaviors are executed <strong>in</strong> a thread-per-agent concurrency model, <strong>in</strong>which there is no stack to be saved: they are managed <strong>by</strong> an <strong>in</strong>ternal scheduler implement<strong>in</strong>ga round-rob<strong>in</strong> non-pre-emptive policy among all the behaviors available<strong>in</strong> the ready queue of an agent [13]. The synchronous characteristic of <strong>in</strong>tra-agentactivity and related cooperative processes makes Jade an attractive agent platform forthe study of the agent behavior <strong>in</strong> the context of telecommunication applications, sothat our AWM_agents have been implemented <strong>in</strong>to the Jade environment. Still, Jade3An excellent overview of project activities concern<strong>in</strong>g <strong>in</strong>telligent agents for network managementcan be found <strong>in</strong> [13].4http://www.fipa.org5http://sharon.cselt.it/projects/jade