Efficient soft QoS guarantee in mobile ad hoc networks

International audienceMore and more Quality of Service (QoS) sensitive applications, such as streaming media, high bandwidth content distribution and VoIP, will be deployed in Mobile Ad hoc Networks (MANETs) as part of the pervasive computing realization. However, traditional QoS guarantee technologies cannot be used directly in MANETs due to the dynamic network environment. This paper proposes a QoS management mechanism combining Caching and Backup Service Paths (CBSP) and an Enhanced CBSP (ECBSP) for soft QoS guarantee in MANETs. In CBSP, Service Provider Nodes (SPNs) with distinct Service Paths (SPs) providing the required service are found in the MANET during the service discovery phase. The client node then selects one SP to get the service and the other SPs as Backup Service Paths (BSPs). If the serving SP fails to serve the client node, the client node can handover quickly to a BSP and consume the resource in its cache during the handover operation in order to avoid service interruption. In ECBSP, the required data are further divided into several segments and transmitted concurrently to the client node through different SPs for enhanced availability. Simulation experiments in ns2 show that CBSP/ECBSP can improve the performance of applications in MANETs effectively

Delay Sensitive Routing For Real Time Traffic Over Ad-hoc Networks

Wireless ad hoc network consists of inexpensive nodes that form a mobile communication network. Due to limitations of the transmission range, the nodes rely on each other to forward packets such that messages can be delivered across the network. The selection of the path along which a packet is forwarded from the source node to the destination node is done by the routing algorithm. Most commonly used routing algorithms, though effective for non-real time applications, cannot handle real-time applications that require strict delay bounds on packet delivery. In this thesis, we propose a routing protocol that ensures timely delivery of real time data packets. The idea is to route packets in such a way that irrespective of factors like traffic load and node density, the average delay remains within acceptable bounds. This is done by carefully accessing the resources available to a route before a session is admitted along that route. Each link in the route is checked for sufficient bandwidth not only for the new session to be admitted but also for the sessions that are already using that link. The new session is admitted only if the admission does not violate the delay bounds of any on-going sessions. This method of route selection coupled with per-hop link reservations allows us to provide bounds on the delay performance. Extensive simulation experiments have been conducted that demonstrate the performance of the proposed routing protocol in terms of throughput, session blocking probability, packet drop probability, average path length, and delay

QoS in Node-disjoint Routing for Ad Hoc Networks

PhDA mobile ad hoc network (MANET) is a collection of mobile nodes that can communicate with each other without using any fixed infrastructure. It is necessary for MANETs to have efficient routing protocol and quality of service (QoS) mechanism to support multimedia applications such as video and voice. Node-Disjoint Multipath Routing Protocol (NDMR) is a practical protocol in MANETs: it reduces routing overhead dramatically and achieves multiple node-disjoint routing paths. Because QoS support in MANETs is important as best-effort routing is not efficient for supporting multimedia applications, this thesis presents a novel approach to provide that support. In this thesis NDMR is enhanced to provide a QoS enabled NDMR that decreases the transmission delay between source and destination nodes. A multi-rate mechanism is also implemented in the new protocol so that the NDMR QoS can minimise the overall delays. It is shown that these approaches lead to significant performance gains. A modification to NDMR is also proposed to overcome some of the limitations of the original