Nadir Shah

A Survey on DHT-Based Routing for Large-Scale Mobile Ad Hoc Networks

Mobile ad hoc networks (MANETs) are infrastructureless and distributed communication systems that require sophisticated approaches to routing to cope with node mobility and heterogeneous application requirements. In the past few years, distributed hash table (DHT) has come forth as a useful additional technique to the design and specification of spontaneous and self-organized networks. Researchers have exploited its advantages by implementing it at the network layer and developing scalable routing protocols for MANETs. The implementation of DHT-based routing in a MANET requires different algorithms and specifications compared to routing in the Internet because a MANET has its unique characteristics, such as node mobility, spontaneous networking, decentralized architecture, limited transmission range, dynamic topology, and frequent network partitioning/merging. In this article, we present a comprehensive survey of research related to DHT-based routing that aims at enhancing the scalability of MANETs. We present a vivid taxonomy of DHT-based routing protocols and the guidelines to design such protocols for MANETs. We compare the features, strengths, and weaknesses of existing DHT-based routing protocols and highlight key research challenges that are vital to address. The outcome of the analysis serves as a guide for anyone willing to delve into research on DHT-based routing in MANETs.

MANET adaptive structured P2P overlay

This paper presents an efficient structured P2P overlay over MANET which better matches to the physical network in term of routing. This feature is achieved by locally building up the minimum-spanning tree (MST) at each peer using the information of the peer’s logical neighbors which are either directly connected (1-hop) or 2-hops away. Using this interconnection structure among the peers, we design a new algorithm to distribute the contents information in the overlay by partitioning the identifier (ID) space among the peers. In this algorithm, each peer maintains a disjoint portion of the ID space. The ID space at a peer may be non-contiguous and each contiguous part is consecutive to the ID space of its directly connected neighbor peers. To route the file-lookup query, each peer builds up a binary search tree (BST) using the knowledge of the ID space of itself and of its directly connected neighbor peers. Simulation results show that our approach outperforms the existing approaches in term of routing overhead, average file-discovery delay, false-negative ratio and average path-stretch value.

3D P2P overlay over MANETs

We study the challenging problems of the mismatch between the overlay and the physical network and the resilience of the overlay structure in peer-to-peer (P2P) protocols over a mobile ad hoc network (MANET). Existing P2P protocols have used inflexible overlay structures to arrange peers and do not consider intra-neighbor relationships of peers when assigning logical identifiers. The intra-neighbor relationships of peers are crucial to exactly interpret the physical proximity of peers in an overlay and to avoid the mismatch between the overlay and the physical network that causes extensive routing overhead, larger average file discovery delay, increased false-negative ratio, and high average path-stretch. In this paper, we present a novel P2P overlay over MANETs that exploits a 3-dimensional overlay and 3D space that takes into account the physical intra-neighbor relationship of a peer and exploits a 3D-overlay to interpret that relationship. In the proposed protocol, each peer runs a distributed algorithm that exploits a 3D-overlay to calculate a consecutive logical identifier to a peer. Moreover, the protocol utilizes the 3D-overlay to maintain multi-paths to a destination peer that provides resilience against a node/link failure. Simulation results show that the proposed 3D-overlay outperforms the existing P2P overlay protocol in terms of routing overhead, average file-discovery delay, false-negative ratio, and average path-stretch.

Cross-Layer Design to Merge Structured P2P Networks over MANET

Peer-to-peer (P2P) network is an alternative of client/server system for sharing resources, e.g. files. P2P network is a robust, distributed and fault tolerant architecture. There are basic two types of P2P networks, structured P2P network and unstructured P2P network. Each of them has its own applications and advantages. Due recent advances in wireless and mobile technology, the P2P network can be deployed over mobile ad hoc network (MANET). We consider the scenarios of P2P network over MANET where all nodes are not the members of P2P network. Due to limited radio range and the mobility of nodes in MANET, there can occur network partition and merging of networks in the physical network. This can also lead to P2P network partition and merging at overlay layer. When two physical networks merge by coming into communication range of each other then their P2P networks would not be connected at overlay layer. Because P2P network operates at application layer as an overlay network. That is their P2P networks are connected in physical network but these P2P networks are disconnected at overlay layer. To detect this situation and merge these P2P networks at overlay layer, we extend the ODACP, an address auto-configuration protocol. Then we propose an approach to efficiently merge P2P networks such that routing traffic is minimized. Considering limited radio range and mobility of nodes, the simulation results shows that CAN over MANET performs better as compared to Chord over MANET in term of routing traffic and false-negative ratio.

Performance comparison of two Anycast based reactive routing protocols for mobile Ad hoc networks

Ad hoc networks (MANET) frequently changing network topology using multi-hop wireless links without existing network infrastructure. Anycast routing is important for Ad hoc network in terms of resource, robustness and efficiency when mobility is high and links get disconnected frequently. Performance of two anycast based reactive routing protocols for mobile Ad hoc networks-Anycast Routing based Dynamic Source Routing (ARDSR) and Anycast routing protocol based on AODV (A-AODV) is evaluated. Performance is evaluated with respect to fraction of packets delivered, end-to-end delay, routing load and energy consumption for given traffic and mobility model. Relative strength, weakness and applicability of each anycast based reactive routing protocol to diverse situations are studied and evaluated.

Performance evaluation of multiple routing protocols using multiple mobility models for mobile ad hoc networks

Mobile ad hoc networks (MANETs) are networks where the nodes are mobile, communicating via wireless link, operating without fixed infrastructure and each node act as a router (forwarding the in transit packets) as well as an end host. The movement of nodes is different in different scenario depending upon applications. Several routing protocols have been proposed by researchers for mobile ad hoc networks. They perform different in different scenarios. The mobility model is one of the main aspects for testing the performance of MANETs routing protocols. We evaluate the performance of multiple routing protocols (DSDV, DSR, OLSR and AODV) using most common mobility models ( random walk, random direction, random way point) for mobile ad hoc networks. We draw the conclusions at the end from the results which will provide the idea of using routing protocol in implementation according to the mobility characteristics of underline scenario. Also we elaborate the weakness and advantages of these routing protocols.

3D-RP: A DHT-based Routing Protocol for MANETs

In the last few years, distributed hash table (DHT) has come forth as a useful addition to the design andspecificationofspontaneous,self-organizingnetworks.Researchershaveexploiteditsadvantages by implementing it at the network layer in order to design scalable routing protocols for mobile ad hoc networks. We identify two correlated issues that must be considered when designing DHTbased routing protocol, namely the mismatch problem and resilience of the logical network, which degrades the efficiency of the DHT-based routing protocols. To address these problems, we propose a DHT-based routing protocol that exploits a 3D logical space that takes into account the physical intra-neighbor relationships of a node and exploits a 3D structure to interpret that relationship. In the proposed scheme, each node runs a distributed algorithm to obtain a consecutive logical identifierthatreflectsitsphysicalproximityinthe3Dlogicalspace.Moreover,theprotocolutilizesthe 3D-structuretomaintainmulti-pathstoadestinationnodeinordertoaddressthescalabilityproblem and gain resilience against a node/link failure. Simulation results show that the proposed approach outperforms the existing DHT-based routing protocol in terms routing overhead, end-to-end delay, path-stretch values and packet-delivery ratio.

An efficient structured P2P overlay over MANET

In traditional structured P2P file sharing network, a peer establishes and maintains connection with a number of neighbor peers according to its ID. This would lead to mismatch between the overlay and physical network in mobile ad hoc network (MANET) due to unique characteristics of MANET. We propose an approach to construct an efficient structured P2P overlay over MANET using underlying OLSR routing. One of the peers in the P2P network is used as a root-peer to connect all peers. Each peer maintains connection with physically closer neighbor peers such that it can reach the root-peer. The peer constructs a minimum-spanning tree consisting of itself, its directly connected neighbor peers and 2-hop away neighbor peers to remove far away redundant links and to build an overlay closer to the physical network. This structure of interconnection among the peers is used to systematically distribute the identifier space among the peers for which a peer is responsible. We can show by simulation that our approach performs better in comparison with the existing approach.

Exploiting 3D Structure for Scalable Routing in MANETs

Avoiding the mismatch between a physical network (PT) and a logical identifier structure (LIS) in a distributed hash table (DHT) based routing for mobile ad hoc networks (MANETs) would prevent the problems of long routes, high path-stretch ratio, and increased traffic overhead. To address this mismatch problem, the proposed scheme exploits a 3-dimensional (3D) logical identifier space (LS), where each node computes a consecutive logical identifier (LID) to route packets. The proposed scheme also utilizes 3D-logical identifier structure (3D-LIS) to maintain multi-paths by exploiting multihops at a node to the destination node. Simulation results show that the proposed protocol is better than existing DHT-based routing protocol.

Context-Aware Routing for Peer-to-Peer Network on MANETs

Peer-to-peer (P2P) network is a decentralized and self organized architecture for the sharing of resources such as files. P2P network on wired network (Internet) has been extensively studied. The advancement in the wireless and mobile technology has lead to the deployment of the P2P filesharing on mobile ad hoc networks (MANETs). The direct deployment of wired P2P network would result in poor performance for mobile ad hoc networks due to node mobility which causes link failure. In this paper we propose an approach based on route lifetime for P2P network on mobile ad hoc networks. With this approach the file is retrieved on the route of maximum lifetime, the more stable one, instead of the shortest (first acquired path) one, as used in current P2P network. This would reduce the link failure, and thus can decrease routing overhead and end-to-end delay, and increase the file delivery ratio. The route lifetime is determined by the context information, such as velocity and inter-node distance. Simulation results show that our approach incomparison with the ORION performs better in term of file delivery ratio, routing overhead and average end-to-end delay.