طرح اسکن با کیفیت برای بهره وری موازنه بار در شبکه های ad hoc وسایل نقلیه (VANETs)

The main terminal devices in vehicular ad-hoc networks (VANETs) are highly mobile moving cars that handoff much more frequently than handheld devices. Nevertheless, frequent handoff or high handoff latency can influence the quality of service (QoS) of real-time network services. Since conventional handoff mechanisms cannot fulfill the requirements of VANET, many fast handoff schemes have been proposed. However, the schemes based on the signal strength of APs (access points) ignore the loading states of different APs and thus cannot utilize the bandwidth effectively. Whenever some APs are very busy, the QoS will be degraded. In order to solve this problem, we can pre-establish the APs and regulate their number according to different traffic types. In this paper, we present a fast handoff scheme for VANET, QualityScan, which decreases the handoff latency and considers loading states of the regional APs simultaneously. By the pre-established AP controller (APC), our scheme gathers the loading states of the APs regularly and predicts network traffic of the next moment. Based on the parameters obtained by passive scanning, the mobile nodes (MNs) can choose the optimal AP for the optimal QoS. According to our simulation analysis, QualityScan not only achieves load balance of the APs, but also improves QoS and handoff efficiency in VANET.