earticle

영어

The construction of a wireless multimedia ad-hoc network needs to go across the mixed environment with the indoor, the wall-penetration, and the outdoor condition. This paper presents our contribution to address the system design aspects of a multimedia-enabled network based on IEEE 802.11g ad-hoc mode. There are distinct differences between indoor and outdoor environment and penetrating the walls stressed the system limit of the 802.11g ad-hoc mode. Therefore, routing decisions should be made intelligently with the environmental respect to maximize the bandwidth support on the end-to-end paths. By investigating the experimental results of the average throughput with the 802.11g adhoc mode, we have collected the different performance characteristics among the indoor, the wall-penetration and the outdoor environment. Via the experiments and analyses, we have observed that the ad-hoc mode had the worst performance within 5 meters in indoor environments. In outdoor environments, TCP seemed to favor either short distance (e.g., 5 meters) or long distance (e.g., 25 meters). On the other hand, the best performance UDP has achieved with the distance of 10 meters. When the wall-enetration occurs, it is important that the routing nodes in the building edge areas are placed close-by within 5 meters.
Given the solid evidences from the baseline experiments, we have embedded the heuristic algorithms into the routing decisions. We have thus simulated a large area of 300 meters by 300 meters with hundreds of routing nodes. After investigating over 100 (randomlygenerated) topology scenarios, the performance results indicate that our proposed scheme produces the higher-bandwidth paths for most of the cases. Even in the less-dense cases, our proposed schemes still can find the better paths with bandwidth about 30% higher than the conventional methods.