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Wireless Approximation for Multiagent Systems

The Agent Technology Center at Czech Technical University (CTU) developed a highly-regarded intelligent agent framework and agent simulator AGLOBE. However, AGLOBE’s communication model used in simulation was boolean; that is, it assumed perfect connection or no connection. While this is better than treating the network environment as a perfectly reliable black-box, it is still a poor approximation for many dynamic network environments and could potentially lead to major failures when testing distributed computing or distributing AI algorithms in the field. While working at CTU in Prague, I developed a shared library intended to provide new and existing agent simulators with facilities for approximating wireless multi-hop communications on mobile ad-hoc networks. Specifically, WAMAS provided a set of communication models and a domain-specific language for manipulating and hooking itself into existing agent simulators. WAMAS is built in the spirit of (and with some code from) the MATES application-layer simulator (developed by a colleague), approximating the lower level networking processes to provide agent simulators with a better model of agent communications on constrained mobile ad-hoc networks.

WAMAS was designed to model wireless networks; the primary wireless properties considered were transmit power decay, finite bandwidth and throughput, and network latency. WAMAS is based upon four core models: improved versions of the link connectivity and data transport models found in MATES as well as new models for media access control and ad-hoc routing. Each model can be thought of as conglomerating and approximating an associated “block” of the OSI model.

An exact connectivity model accounts for link quality degradation due to transmit power decay. Sharing the finite bandwidth to simultaneously transmit multiple packets can be considered a very rudimentary approximation of frequency division multiple access bandwidth allocation. Dijkstra was used as a zeroth-order approximation of introducing a multihop ad-hoc routing into the network. A data transport model was used to define the amount of time (simulator iterations) required for an entity to be sent over a specific link (usually a function of the link quality and the size of the entity).

Once the models were constructed and the standalone WAMAS library was complete, it was integrated into AGLOBE as an alternative replacement for the existing boolean communication system. If used in future studies, the research into communication, distributed computing and distributed artificial intelligence will now have a better approximation for realistic wireless communications, improving the quality of results obtained using AGLOBE for agent research (or any agent simulator integrating the WAMAS library).

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