In mobile ad hoc networks (MANETs), there is frequently disconnected a route consisting of multi-hop from a source to a destination because of the dynamic nature such as the topology change caused by nodes’ mobility. To overcome this situation, existing routing protocols for MANETs have performed route repair scheme to repair the disconnected route. However, existing reactive routing protocols have the problem which is that a source node unnecessarily performs re-discovers the whole path when just one node moves, even if the rest of path needs not to be re-arranged. Therefore, the time for re-discovery of the whole path may often take too long. To solve the problem, we propose a new local repair scheme using promiscuous mode. Our scheme is mainly composed of two parts: adaptive promiscuous mode and quick local repair scheme. Adaptive promiscuous mode is to repeat the switching processes between promiscuous mode and nonpromiscuous mode to overcome energy limit caused by using promiscuous mode in overall time and quick local repair scheme is to fast perform the local re-route discovery process with the information of the active connection in the local area acquired by promiscuous mode. With simulation in the various number of connection, We demonstrate the better network performances achieved with the proposed schemes as compared with AODV as reference model that do not provide local repair scheme.
To reserve end-to-end bandwidth in quality of service (QoS) supported wireless ad hoc networks, local bandwidth requirement should be carefully determined by considering the number of contending nodes in an interference range. In this article, we propose a novel admission control protocol, called DACP (distributed admission control protocol), which is implemented over a reactive ad hoc routing protocol with minimal overhead. DACP computes the required bandwidth for end-to-end band-width provision at each node and estimates the available bandwidth at the medium access control layer. After that, DACP makes a decision for admitting a flow in a per-hop basis. Extensive simulations are carried out via the OPNET simulator. The simulation results demonstrate that DACP not only provides guaranteed end-to-end resource but also reduces the control overhead to provide QoS support, compared with the existing admission control schemes.
Due to advances in wireless communications and portable terminals, any-time, any-where, and any-device Internet access is possible.In particular, Internet access in moving vehicles is an emerging and challenging issue. Even though a variety studies have been conduced for vehicular networks, little attention is paid to vehicular Wi-Fi networks where a Wi-Fi access point (AP) is installed at the vehicle and the AP is connected to an external base station (BS). In this paper, we conduct a measurement study on the uplink and downlink throughput for Internet access in vehicular Wi-Fi networks. We consider diverse network environments: high-speed train, car, and subway. Measurement results demonstrate that current Internet access in vehicular Wi-Fi networks are not satisfactory for interactive multimedia applications. Therefore, in-depth study on resource management in vehicular Wi-Fi networks is strongly required.
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