position based opportunistic routing protocols for highly dynamic mobile ad- hoc networks

International Journal of Computer Trends and Technology (IJCTT) – volume 4 Issue10 – Oct 2013

ISSN: 2231-2803 http://www.ijcttjournal.org Page3390

Position Based Opportunistic Routing Protocols for Highly Dynamic Mobile Ad-

Hoc Networks Rajesh Naidu#1, A.Syam Prasad*2

#1Student, Computer Science Engineering, MRCET, Hyderabad, Andhra Pradesh, India #2 Associate Professor, Department of CSE, MRCET, Hyderabad, Andhra Pradesh, India

Abstract- Communications in Mobile Ad Hoc Networks in emergency situations play an important role. In such network reliability of packet delivery is indispensable as the information exchange accuracy has to be guaranteed. At the same time information has to be reached to the intended node in timely fashion. The existing solutions are vulnerable to node mobility. To overcome this problem, of late, Position-based Opportunistic Routing (POR) protocol was introduced by Yang et al. which makes use of geographic routing wireless medium. When data packets are sent through network some node overhear. One of the nodes that overhear the packet will act as forwarding node. Thus the protocol ensures reliable communication in MANET. In this paper we implement the scheme proposed by Yang et al. Our prototype application, a custom simulator, demonstrates the proof of concept. The empirical results revealed that the prototype is useful for further research and improvement in MANET communications. Index Terms – Opportunistic forwarding, reliable communications, mobile ad hoc networks, void handling

I. INTRODUCTION

MANETs have become popular and ubiquitous in usage as the network is infrastructure less with significant advantages. There is an issue pertaining to dynamic nature of topology and error prone wireless channel. This will cause the network lacking in reliable communications in timely manner. Traditional routing protocols that govern communication in MANETs such as DSR, AODV and DSDV [1] are vulnerable to node mobility. The reason behind this is the router determination prior to data transmission. A deterministic route is not feasible as the network changes dynamically. The procedures used by the protocols for recovery and discovery are time consuming. In case of path break situations they consume more energy causing the network lifetime to be lessened. Location information is used by Geographical Routing [2] for forwarding packets in hop-by-hp manner. The next hop forwarder is identified using greedy forwarding mechanism. Void handling mechanism is also used to achieve the communication [3]. GR lets the network to have high efficiency and scalability. However, it is sensitive to information

pertaining to location [4]. The transmission fails when the far away node is selected for forwarding. In case of GPSR failure of MAC layer details are taken as feedback for giving a packet to take another chance for routing. As the MANETs are wireless it exhibits broadcasting feature. This may lead to reception of packet multiple times. Opportunistic routing [5], [6], [7] protocols are efficient to handle broadcasting kind of communications. These protocols make use of link – state to determining candidates for forwarding. In this case finding inter-node loss rate is not easy. These protocols also cause delay in delivering packets due to the batching concept. In [8] OR which is location – aided was introduced for forwarding packets. However, in all existing works, opportunistic forwarding is not fully exploited. Recently Yang et al. [9] explored the Position – based Opportunistic Routing (POR) for forwarding packets to make the MANET for communications to be timely and reliable. This protocol exploits the multipaths explored at runtime for achieving robustness of POR. The remainder of the paper is structured as follows. Section II reviews important literature pertaining to reliable communications in MANETs. Section III provides details of proposed protocol. Section IV provides implementation details. Section V presents experimental results while section VI concludes the paper.



II. PRIOR WORKS

In wireless networks for reliable communication some degree of redundancy is introduced. However, this straight forward solution is not robust. All the existing protocols that make use of this redundancy in one way or other are classified into two types. The first one is known as multipath routing which makes use of end-to-end redundancy. The second approach uses hop-by-hop redundancy which makes use of broadcast nature of wireless medium. In this paper, the second approach is used. Multipath routing protocols were introduced for improving reliability in communications [10]. These protocols support establishing many paths between the source and destination. The multipath routing protocols which are already existed are classified into three categories. The first category protocols use alternate paths as backup [11], [12], and [13]. The second category use a technique known as packet replication among multiple paths [14], [15]. The third category uses the features of multipath deliver, coding techniques and reconstruction [16], [17]. It is not easy to find independent paths which are suitable. Especially in case of highly dynamic nature of MANETs make it difficult to use such strategies. Recently broadcast nature of wireless medium is exploited for opportunistic forwarding that improves throughput of network [6], [7]. With respect to MANET, opportunistic routing can improve performance of the network. This is explored in [18] which boost the performance using Receiver Signal Strength Indicator [RSSI] which can prioritize relay nodes. By assigning higher priority it is possible to ensure high packet delivery. In [19] the impact of mobility is explored using WiFi network. The cooperative communications were explored. However, it failed in producing positive results as there was no strict coordination achieved between the base stations. It also resulted in false negatives and false positives. The experiments were made in WLANs. In [20] robust routing in wireless sensor networks was focused. Recently Yang et al. [9] introduced opportunistic routing protocol which makes use of stateless feature of geographic routing and broadcast nature of wireless medium in order to achieve reliable and timely communications in MANETs.

III. POSITION BASED OPPURTUNISTIC

ROUTING

There are two techniques on which this routing mechanism is built. They are known as opportunistic forwarding and geographic routing. We assume that the nodes in the MANET are aware of their own location and also the location of their neighbors. The topology considered for the experiments is as shown in figure 1.

Fig. 1 – Topology of MANET

As can be seen in figure 1, the source and destination nodes are in red color. Their position is fixed. They are assumed to have no mobility. The other nodes in MANET have mobility as they can move based on the model described in the previous section. Before describing the functionality of the routing mechanism, some terms are defined here. The ratio of number data packets delivered from source and the number of data packets received is known as packet delivery ratio. The average delay is known as end-to-end delay. The average end-to-end length of the path is known as path length. Packet forwarding times per hop (FTH) and packet forwarding times per packet (FTP) are other terms which are self describing. The FTH is computed as follows.

The FTP is computed as follows.

Prioritization of Forwarding Candidates



Selection and prioritization of forwarding candidates is very important for opportunistic routing of packets in MANET. The following algorithm is used to choose and priotize forwarder list.

Fig. 1 – Candidate selection algorithm (excerpt from

[9])

For enhancing the robustness of the POR where there is not uniform distribution of nodes found in the network, and due to the existence of large holes, a mechanism known as void handling is used. In order to handle voids in communication, the existing solutions find alternative route. While handling void greedy forwarding cannot be used. It is also not possible to exploit the multicast nature of wireless media. Instead virtual destination concept is used to achieve this. Virtual destination is the temporary destination to which packets are forwarded. These virtual destinations guide packet delivery thus achieving reliable transmissions in timely fashion. More details of the reliable transmission mechanism can be found in [9].

IV. PROTOTYPE IMPLEMENTATION

We built a custom simulator, a prototype application that demonstrates the proof of concept. The prototype is built using Microsoft .NET platform. The environment used to build the application includes a

PC with 4 GB RAM, core 2 dual processor running Windows 7 operating system. We did several experiments and the results are presented in section IV.

V. EXPERIMENTAL RESULTS

We built a prototype application which is a simulator developed in Microsoft .NET platform. We considered 80 nodes for simulation. The source and destination are fixed while the remaining nodes have mobility. The node mobility is controlled by the model proposed in this paper. Experiments are made in terms packet delivery ratio, mobility of nodes, expected forwarding times, median end to end delay, path length or number of hops and so on. The experimental results are presented as a series of graphs as given below.

Fig 2 Analytical delivery ratio versus node mobility. As shown in the above figure 2 represents the horizontalaxis represents maximum speed while vertical axis represents analytical delivery ratio.

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Fig 3 Analytical delivery ratio versus node mobility. As shown in the above figure 3 represents the horizontal axis represents maximum speed while vertical axis represents analytical delivery ratio.

Fig 4 EFT with different N. As shown in the above figure 4 represents the horizontal axis represents P while vertical axis represents expected forwarding times.

Fig 5 Forwarding candidate number evaluation of Median end-to-end delay As shown in the above figure 5 represents the horizontal axis represents P while vertical axis represents Median end-to-end delay.

Fig 6 Simulation results of Packet delivery ratio

As shown in the above figure 6 represents the horizontal axis represents P while vertical axis represents Packet delivery ratio.

Fig 7 Simulation results of Path length As shown in the above figure 7 represents the horizontal axis represents P while vertical axis represents Path length. VI. CONCLUSIONS

In this paper we built a prototype, customer simulator, application that demonstrates reliable data delivery in MANET. As the nodes in the network are highly dynamic in nature, it is important to ensure that the data is delivered reliably. Due to the dynamic nature of the network, the conventional protocols are inadequate to achieve reliable data transfer in timely manner. To overcome this we have implemented a routing protocol proposed by Yang et al. [9] which demonstrates the reliable and timely delivery of data packets in MANETs. This work has been inspired by opportunistic routing which exploits the broadcast

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nature of wireless medium and stateless feature of geographical routing. This protocol ensures that the packet forwarding takes place by nodes those overhead packets. The network also has some explicitly specified nodes for packet forwarding in case of link break. This will help in reliable communication in timely manner. We implement a prototype custom simulator that demonstrates the proof of concept. The empirical results revealed that the prototype is useful for further research and enhancement of reliable communications in MANETs. REFERENCES [1] J. Broch, D.A. Maltz, D.B. Johnson, Y.-C. Hu, and J. Jetcheva,

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Authors



Rajesh Naidu, he is pursuing M.Tech (CSE) in MRCET, Hyderabad, AP, INDIA. He has received B.Tech Degree in Computer Science and Engineering. His main research interest includes data mining, Databases and DWH.

Syam Prasad.A He is currently with the Department of Computer Science and Engineering, MRCET, Andhra Pradesh,India. He has received M.Tech Degree from JNTU. His main research interest includes data mining, Databases and DWH.

position based opportunistic routing protocols for highly dynamic mobile ad- hoc networks

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