An Effective Capacity Estimation Scheme in IEEE802.11-based Ad Hoc Networks

ABSTRACT Capacity estimation is a key component of any admission control scheme required to support quality of service provision in mobile ad hoc networks. A range of schemes have been previously proposed to estimate residual capacity that is derived from window-based measurements of channel estimation. In this paper a simple and improved mechanism to estimate residual capacity in IEEE802.11-based ad hoc networks is presented. The scheme proposes the use of a 'forgiveness' factor to weight these previous measurements and is shown through simulation-based evaluation to provide accurate utilizations estimation and improved residual capacity based admission control

A new routing protocol for ad hoc wireless networks design, implementation and performance evaluation

A collection of mobile nodes can form a multi-hop radio network with a dynamic topology and without the need for any infrastructure such as base stations or wired network. Such a Mobile Ad Hoc Networks (MANETs) maintain their structure and connectivity in a decentralised and distributed fashion. Each mobile node acts as both a router for other nodes traffic, as well as a source of traffic of its own In this thesis we develop and present a new hybrid routing protocol called Multipath Distance Vector Zone Routing Protocol, which is referred to as MDVZRP. In MDVZRP we assume that all the routes in the routing table are active and usable at any time, unless the node received or discovered a broken link. There is no need to periodically update the routing tables, therefore reducing the periodic update messages and hence reducing the control traffic in the entire network. The protocol guarantees loop freedom and alternative disjoint paths. Routes are immediately available within each routing zone. For destinations outside the zone, MDVZRP employs a route discovery technique known as routing information on demand. Once the node is informed by either the MAC layer or itself that it should discover the non- reachable nodes, MDVZRP adopts a new technique. First, we discuss the Ad Hoc networks and routing in general, then the motivation of MDVZRP regarding the nodes‟ flat view, and the selection and acquisition of multipath getting and selection. Furthermore, we describe the stages of MDVZRP and the protocol routing process with examples. The performance of MDVZRP is then evaluated to determine its operating parameters, and also to investigate its performance in a range of different scenarios. Finally, MDVZRP is compared with DSDV and AODV ordinary routing protocols (standard) delivering CBR traffic. Simulation results show that MDVZRP gives a better performance than DSDV in all circumstances, it is also better than AODV in most of the scenarios, especially at low mobility

A new routing protocol for ad hoc wireless networks design, implementation and performance evaluation

A collection of mobile nodes can form a multi-hop radio network with a dynamic topology and without the need for any infrastructure such as base stations or wired network. Such a Mobile Ad Hoc Networks (MANETs) maintain their structure and connectivity in a decentralised and distributed fashion. Each mobile node acts as both a router for other nodes traffic, as well as a source of traffic of its own In this thesis we develop and present a new hybrid routing protocol called Multipath Distance Vector Zone Routing Protocol, which is referred to as MDVZRP. In MDVZRP we assume that all the routes in the routing table are active and usable at any time, unless the node received or discovered a broken link. There is no need to periodically update the routing tables, therefore reducing the periodic update messages and hence reducing the control traffic in the entire network. The protocol guarantees loop freedom and alternative disjoint paths. Routes are immediately available within each routing zone. For destinations outside the zone, MDVZRP employs a route discovery technique known as routing information on demand. Once the node is informed by either the MAC layer or itself that it should discover the non- reachable nodes, MDVZRP adopts a new technique. First, we discuss the Ad Hoc networks and routing in general, then the motivation of MDVZRP regarding the nodes‟ flat view, and the selection and acquisition of multipath getting and selection. Furthermore, we describe the stages of MDVZRP and the protocol routing process with examples. The performance of MDVZRP is then evaluated to determine its operating parameters, and also to investigate its performance in a range of different scenarios. Finally, MDVZRP is compared with DSDV and AODV ordinary routing protocols (standard) delivering CBR traffic. Simulation results show that MDVZRP gives a better performance than DSDV in all circumstances, it is also better than AODV in most of the scenarios, especially at low mobility

Performance evaluation of shortest multipath source routing scheme

Multipath routing in mobile ad-hoc networks allows the establishment of multiple paths for routing between a source-destination pair. It exploits the resource redundancy and diversity in the underlying network to provide benefits such as fault tolerance, load balancing, bandwidth aggregation and the improvement in quality-of-service metrics such as delay. Previous work shows that on-demand multipath routing schemes achieve better performance under certain scenarios with respect to a number of key performance metrics when compared with traditional single-path routing mechanisms. A multipath routing scheme, referred to as shortest multipath source (SMS) routing based on dynamic source routing (DSR) is proposed here. The mechanism has two novel aspects compared with other on-demand multipath routing schemes: it achieves shorter multiple partial-disjoint paths and allows more rapid recovery from route breaks. The performance differentials are investigated using NS-2 under conditions of varying mobility, offered load and network size. Results reveal that SMS provides a better solution than existing source-based approaches in a truly mobile ad-hoc environment