• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1026-1031
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• 2022

Cognitive Radio Ad-Hoc Networks (CRAHNs) enable to overcome the shortage of frequency resources due to the increase of radio services. In order to avoid interference with the primary user in CRANH, channel sensing to check the idle channel is required, and when the primary user appears, the time delay due to handover should be minimized through fast idle channel selection. In this paper, throughput was improved by reducing the number of channel sensing and preferentially sensing a channel with a high probability of being idle, using reinforcement learning. In addition, we proposed a multi-channel MAC (Medium Access Control) protocol that can minimize the possibility of collision with the primary user by sensing the channel at the time of data transmission without performing periodic sensing. The performance was compared and analyzed through computer simulation.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.107-118
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• 2015

Many approaches to agent collaboration have been introduced in military war-games, and those approaches address methods for simulation entity (actor) collaboration within a team to achieve given goals. To meet fast-changing battlefield situations, an actor must be loosely coupled with their tasks and be able to take over the role of other actors if necessary to reflect role handovers occurring in real combat. Achieving these requirements allows the transfer of tasks assigned one actor to another actor in circumstances when that actor cannot execute its assigned role, such as when destroyed in action. Tight coupling between an actor and its tasks can prevent role handover in fast-changing situations. Unfortunately, existing approaches and war-game strictly assign tasks to actors during design, therefore they prevent the loose coupling. To overcome these shortcomings, our Role-based Command Hierarchy (ROCH) model dynamically assigns roles to actors based on their situation at runtime. In the model, "Role" separates actors from their tasks. In this paper, we implement the ROCH model as a component that uses a publish-subscribe pattern to handle the link between an actor and the roles of its subordinates (other actors).