Modeling and performance analysis using extended fuzzy-timing Petrinets for networked virtual environments

摘要

Despite their attractive properties, networked virtualnenvironments (net-VEs) are notoriously difficult to design, implement,nand test due to the concurrency, real-time and networking features innthese systems. Net-VEs demand high quality-of-service (QoS) requirementsnon the network to maintain natural and real-time interactions amongnusers. The current practice for net-VE design is basically trial andnerror, empirical, and totally lacks formal methods. This paper proposesnto apply a Petri net formal modeling technique to a net-VE-NICEn(narrative immersive constructionist/collaborative environment), predictnthe net-VE performance based on simulation, and improve the net-VEnperformance. NICE is essentially a network of collaborative virtualnreality systems called the CAVE-(CAVE automatic virtual environment).nFirst, we introduce extended fuzzy-timing Petri net (EFTN) modeling andnanalysis techniques. Then, we present EFTN models of the CAVE, NICE, andntransport layer protocol used in NICE: transmission control protocoln(TCP). We show the possibility analysis based on the EFTN model for thenCAVE. Then, by using these models and design/CPN as the simulation tool,nwe conducted various simulations to study real-time behavior, networkneffects and performance (latencies and jitters) of NICE. Our simulationnresults are consistent with experimental data