The optimisation of peer-to-peer overlays for mobile ad-hoc networks

Millar, Grant P. (2013) The optimisation of peer-to-peer overlays for mobile ad-hoc networks. (PhD thesis), Kingston University, .

Abstract

The proliferation of smart devices and wireless interfaces has enabled the field of Mobile Ad-hoc Networks (MANETs) to flourish as the technology becomes realistically deployable. MANETs are created by a group of autonomous nodes that communicate with each other by establishing a multihop radio network and maintain connectivity in an infrastructureless and decentralised manner. Thus it becomes more important to examine how applications such as those used on the Internet can be deployed on top of such MANETs. Peer-to-peer (P2P) networks can be defined as decentralised application-layer overlay networks where traffic flows on top of the physical network such as the Internet. Such networks are formed dynamically on-the-fly and rely on no fixed infrastructure such as servers. On the Internet a great number of applications have exploited the properties of P2P networks, thus they have been used to provide services such as distributed data storage systems, distributed instant messaging systems, publish/subscribe systems, distributed name services Voice over IP (VolP) services and many more. This thesis proposes three novel P2P protocols. Reliable Overlay Based Utilisation of Services and Topology (ROBUST), which minimises end-to-end lookup delay while increasing lookup success rate compared with current state-of-the-art and is usable on any MANET routing protocol. It achieves this by using a hierarchal clustered topology where peers are clustered together with other peers in close proximity in order to reduce P2P routing hops and create a more efficient network. Proactive MANET DHT (PMDHT), which combines proactive MANET routing and DHT functionality in order to minimise end-to-end lookup delay while increasing lookup success rate compared with current state-of-the-art. This is achieved by heavily integrating the P2P functionality - by piggy-backing P2P messages on to routing messages - at the network layer using the proactive MANET routing protocol Optimized Link State Routing version 2 (OLSRv2). Using this method the P2P overlay topology exactly matches that of the underlying network, while all peers are fully aware of the state of that topology. This means the P2P lookups can be completed in one logical step. Reactive MANET P2P Overlay (RMP2P), which combines reactive MANET routing and DHT functionality in order to minimise end-to-end lookup delay while increasing lookup success rate compared with current state-of-the-art. in RMP2P we combine P2P lookup functionality with the MANET routing protocol Ad-hoc On-demand Distance Vec¬tor version 2 (AODVv2). In this case we piggy-back P2P lookups on to the routing request messages if possible, decreasing overhead and latency in the network. We evaluate the performance of the proposed novel architectures by developing a custom made packet level simulator using ns-2 (network simulator-2), the results show that these architectures out perform the current state-of-the-art P2P overlays in specific scenarios. The ROBUST protocol is suited to scenarios where the underlying routing protocol cannot be modified. The PMDHT protocol performs best overall in networks which require more scalability. The RMP2P protocol performs best in networks with high mobility. We end this thesis with our conclusions and avenues for future work in the field of P2P networks for MANETs.

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