A Proposed Routing Protocol for MANET

Transcription

1 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: A Proposed Routing Protocol for MANET Mamoun Hussein Mamoun Faculty of Computer and Information Sciences Mansoura University, Egypt mamooninf@yahoo.com Abstract-- Many routing protocols have been designed for Ad Hoc networks. However, most of these kinds of protocols are not able to react fast enough to maintain routing. This paper presents a Proposed Routing Protocol () that repairs the broken route by using information provided by nodes overhearing the main route communication. When links go down, our protocol intelligently replaces these failed links or nodes with backup ones that are adjacent to the main route. Experimental results show that our protocol finds a backup route around 50% of cases and achieve better performance in term of the packet delivery rate than the major Ad Hoc routing protocols, but with much less overhead. Index Term-- MANET, DSR, New routing protocol for MANET 1. INTRODUCTION Wireless networks emerged in the 1970 s, since then they have became increasingly popular. The reason of their popularity is that they provide access to information regardless of the geographical location of the user. They can be classified into two categories: infrastructure and infrastructureless networks. Infrastructure wireless networks, also known as cellular networks, have permanent base stations which are connected to other base stations through links. Mobile nodes communicate with another one through these base stations. Infrastructureless wireless networks, also known as ad hoc wireless networks, are a collection of wireless nodes that does not have any predefined Infrastructure or centralized control such as base stations or access points [1]. Ad hoc wireless networks are different from other networks because of following characteristics: absence of centralized control, each node has wireless interface, nodes can move freely which results in frequent changes in network topology, and nodes have restricted amount of resources and lack of symmetrical links. In wired networks, shortest path is usually obtained with distance vector or link state routing protocols. These protocols do not perform well in ad hoc wireless networks because wireless networks have limited bandwidth and there is not central control. Therefore, modifications to these routing protocols or entirely new routing protocols are required for the ad hoc wireless networks [1, 2 and 3]. Table-driven, ondemand and hybrid routing protocols are three main categories of routing protocols for ad hoc wireless networks: -Table driven routing algorithms: Destination Sequenced Distance Vector (DSDV) [2], Clustered Gateway Switch Routing (CGSR) [3], Wireless Routing Protocol (WRP) [4]. Table driven routing algorithms are also called proactive algorithms. Protocols that use this algorithm find all paths between source-destination pairs in a network and form the newest path with periodic route updates. Update messages are sent even if there are no topological changes. The protocols which are in this category are developed by changing distance vector and link state algorithms. These protocols store routing information in routing tables and give result very slowly because of periodic update of tables. This working strategy is not very suitable for wireless ad hoc networks because of a great deal of routing overload [2]. -On demand routing algorithms: Dynamic Source Routing (DSR) [4], On-Demand Distance Vector Routing () [5], Temporally Ordered Routing Algorithm (TORA) [2], Zone Routing Protocol (ZRP) [6] Unlike table driven algorithms, on demand routing algorithms do not form route information among nodes. Routes are founded only in case of necessity. Routes are formed only when needed, in other words when any of the nodes wants to send a packet. Therefore, routing overload is less than table driven algorithms. However, packet delivery fraction is low because every node does not keep updated route information. Dynamic source routing (DSR): In this algorithm, sender node determines the entire route of sent packet and adds the determined route information to the header of packet. This process can be made as static or dynamic. DSR protocol uses dynamic source routing. DSR algorithm does not send periodic updates. However, there is routing overload because all route information is added into each data packet. This overload increases in state of mobility and traffic density. -Hybrid routing algorithms: Multi Point Relaying (MPR) based algorithms [7], Position based algorithms: Directional routing algorithm (DIR), most forward within radius (MFR), geographic distance routing (GEDIR) [8], distance routing effect algorithm for mobility (DREAM) [9], Voronoi-GEDIR (V-GEDIR) [10]. Hybrid routing algorithms aim to use advantages of table driven and on demand algorithms and minimize their disadvantages. Position based routing algorithms that is

2 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: classified in the hybrid routing algorithms category include the properties of table driven and on demand protocols and are usually interested in localized nodes. Localization is realized by GPS that is used to determine geographical positions of nodes. Position changes which occur because of nodes mobility in MANET cause changes in routing tables of nodes. The GPSs, which are embedded in nodes, are used to update information in tables in position-based algorithms. That makes positionbased algorithms different from the table driven and on demand algorithms. The GPSs have become preferred systems as they provide latitude, longitude and height values at high reliability and low cost. Some of the GPS based hybrid routing algorithms are: directional routing algorithm (DIR), most forward within radius (MFR), geographic distance routing (GEDIR) and distance routing effect algorithm for mobility (DREAM). Geographic distance routing (GEDIR) algorithm uses geographical information of neighbor and destination nodes in order to determine message packet receivers. The meaning of the neighbor node is the closest node to target node. Algorithm determines the target within a few CPU cycles [11]. GEDIR algorithm use only latitude and longitude parts of geographical information of whole nodes. Every node knows geographical positions of only its own neighbors. Sender knows the location of target node at the same time. When node A wants to send message m to node D, it uses location information of D and location information of the closest one to D among which are 1-hop neighbors. Distance routing effect algorithm for mobility (DREAM), one of the improved algorithms based on node position information, was suggested in [9]. According to DREAM, the position information obtained by GPS of whole nodes in the network is stored in every node s routing table. This algorithm is a table driven algorithm since it holds information belonging to whole nodes. According to the algorithm, while node A is sending m message to node B, it uses its position information in order to determine B s direction. Then it sends m message to 1- hop neighbour on B direction. Each neighbour repeats the same process. This process continues until message arrives to B (if possible). It resembles on demand algorithms in this respect. The V-GEDIR is another of the position-based algorithm [10]. In this method, the intersection nodes are determined with destination s possible circular or rectangular voronoi diagram. Another position-based algorithm suggests reducing number of route demander transmitter nodes [12]. The algorithm called Location Aided Routing (LAR) algorithm handles route finding by reducing the search area [13]. GEDIR, MFR, DIR and DREAM calculate internodal position information (latitude and longitude) to decide routing. In this paper, LAHRP has been proposed. In general, the existing routing protocols either need to maintain routing information from each node to every other node in the network or try to create routes on a non-demand basis. Maintaining routing information takes a large portion of network capacity, even though most of the information is never used. On the other hand, the on-demand methods usually incur quite a significant latency in order to determine a route. When the rate of topological changes in the network is sufficiently high, most of the existing protocols may not be able to react fast enough to maintain necessary routing. In this paper, we propose a new routing algorithm, which overcomes the drawback associated with the conventional routing algorithms. Simulations show that the proposed algorithm achieves better in most aspects than most of these notable protocols, and with much less overhead. The rest of paper is organized as follow. In Section 2, we give a survey of how relevant routing protocols react to link failure. The main ideas of our algorithm are described in Section 3, with experimental results of our proposed protocol presented in Section 4. We conclude the paper in Section THE PROPOSED NEW ROUTING PROTOCOL Here we present a new fully distributed and on-demand based Ad Hoc routing protocol with nearly real time repairable route that handles the broken-link recovery in more efficient way. Before moving on to the details, we present the intuitive ideas behind our protocol in the following. The proposed routing protocol begins by finding a route from a source S to a destination D, which we call the main route. All data packets are then sent along this main route to the destination. As the data packets proceed to move along the main route, nodes that are close enough to the path will overhear the messages. In other word, nodes that are able to overhear the messages should be close to the main route and are potentially good candidates for substituting the failed node. By piggybacking appropriate information within packets and applying proper procedure, our algorithm makes nodes that overhearing the packets the backup nodes for future route reconstruction in case of broken main route. Other than adding an additional field (for storing height value, as explain later) to a node s route table and header of message, there is no need for frequent message flooding and huge table maintenance. Our protocol consists of route construction and maintenance stages. Detailed description is given as follows. 2.1 Route Construction In our proposed routing protocol, a routing path is constructed only when a node needs to communicate with another node. Assume that a source node S wants to send a packet to some destination node D. If the destination node D is a neighbor of source node S, the packet is sent directly to node D. Otherwise, the source node will first check if node D is in its main route table (MRT). If it is, packets will then be sent directly to the next-hop node as specified by the entry. On the other hand, a path (the main route) from source node S to destination node D need to be constructed before source node S can start the data transmission. The process of finding such a

3 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: routing path is called the main route construction, which begins with the source node S sending a main route request (MREQ) to all its neighbors. Every host that receives the MREQ acts exactly the same as the source node does. MREQ is thus flooded over the network, and would eventually arrive at node D if a routing path exists between them. When node D receives a MERQ, it sends back main route reply (MRRP) and a value H, representing the hop number from this node (D) to the destination (which is zero in this case), to the host from which MREQ was received. Once a node receives MREQ, it adds a main route entry for node D to its MRT. It then propagates the MRRP, together with value H+1, to the host from which it receives the MREQ. Every other host receiving MRRP behaves similarly until node S receives MRRP and updates its MRT accordingly. A routing path from node S to D, referred to as the main route, is thus established. 2.2 Route Maintenance The route maintenance process consists of two parts: the main route messages sniffering and the main route repairing. In main route messages sniffering stage, our concern is how to manage the messages go through the main route that is overheard by the neighboring nodes. With main route repairing, we need to take care of a broken main route using the messages collected and avoid the flooding of repair query (REPQ) packets as long as possible. The Main Route Messages Sniffering: The main route messages sniffering stage begins as packets start delivering through the main route. However, we need to modify the packets delivery slightly to accomplish this task. First of all, we need to insert an H field into the header of data packet and require the nodes to maintain an extra height table for storing the H value. Secondly, with the broadcast nature of wireless communication, a node promiscuously overhears packets transmitted by nodes that are within the radio range. In case a node, which is not a part of the main route, overhears a data packet transmitted by a neighbor on the main route, it records the H value within the packets header into its height table. If more than one such packet is received, the average of the received H values are computed and then recorded in its height table. The recorded H value can later be used to assist repairing of the route and to restrain flooding of control packets. The Main Route Repairing: When a link on the main route is broken, the upstream node of this link would find out in a period of time and then initiate the main route repairing process by broadcasting a repair query (REPQ) packet. The REPQ packet contains the height value of the initiating node. Each node that receives the REPQ packet would first check if it has a route to the destination. If it does, a repair reply (REPR) packet is sent back to the node from which the repair query (REPQ) packet was received and the route repairing process is done. Otherwise, it compares the height value (denotes Hreq) contained in the REPQ packet to its own height value (denotes Ht) in the height table to determine what the next step will be. In case Hreq is greater than (or equal to) Ht, which means very likely the route repairing request was sent from a node that is closer (or as close) to the source node, the receiving node would then rebroadcast the REPQ and hope the REPQ packet would propagate to the nodes that are closer to the destination. However, if Hreq is smaller than Ht or the node has no Ht in its height table, the REPQ packet will be dropped. 3. PERFORMANCE OF THE PROPOSED PROTOCOL Our proposed routing protocol described in previous section is simple, straightforward and should be viable to be included in any Ad Hoc networks without incurring much overhead. In this section, we will demonstrate how it performs as comparing to some major routing protocols. We use GloMoSim [14], which was adopted in numerous researches to evaluate the performance of existing Ad Hoc routing protocols [15, 16], as the simulation tools. The link layer of our simulator is IEEE Distributed Coordination Function. Physical and data link layer models are devised and described in [15]. The simulation environment is a 1500 by 1500 meters rectangular region with 100 mobile nodes moving around. Each of the 100 nodes is placed randomly inside the region. Once the simulation begins, each node moves toward a randomly selected direction with a random speed ranges from 0 to 50 meters per second. Upon reaching the boundary of the rectangular region, the node pauses for a few seconds, then selects another direction and proceeds again as described earlier. The simulation period is set to 500 seconds for each simulation. The radio coverage region of each mobile node is assumed to be a circular area with 250 meters in diameter. The transmission time for a hop takes seconds, and the beacon period is one second. We assume the source node sends a data packet every half second (CBR: Constant Bit Rate), and use UDP as the transport protocol. Each data packet contains 512 bytes, and totally 920 data packets are sent. Each node has a queue, provided by network interface, for packets awaiting transmission that holds up to 50 packets and managed in a drop-tail fashion. One sourcedestination pair is selected arbitrarily from 100 nodes in each simulation. Each simulation scenario represents an average of at least 150 runs. Three on-demand protocols including TORA, DSR, and are used as the basis of comparison to our protocol. These three models and protocols described above are all supported natively by NS-2. Four aspects in evaluating how these algorithms perform are simulated and given in the following four subsections, include (1) data delivery rate, (2) routing overhead, (3) communication latency and (4) average number of hops a message needs to traverse to reach its destination.

4 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: Effectiveness in Repairing Broken Route The first thing we would like to know is how the proposed protocol performs in term of broken route repairing. The experimental simulation result shows that in around 50% of cases of the simulations, the broken routes can be repaired, as shown in Table I. As can be expected, the successful repair rate increases in accordance with the pause time since longer pause time implies more stable nodes. Table I Percentage of Successful Route Repair Percentage of Successful Repair % % % % % 3.2 Packet Delivery Ratio Figure 1 shows the simulation results in packet delivery ratio. Packet Delivery Ratio (%) Fig. 1. Packet delivery fraction vs. Pause time It can be easily seen that our protocol performs approximately as good as (or better than) in terms of packet delivery rate. In fact, in all the simulation scenarios, the margins are all around 1% range, with. 3.3 Routing Overhead Routing overhead, in term of number of control packets sent, is presented in Figure 2. We can see that our proposed protocol has much lower overhead than that of. No. of Control Packets Fig. 2. Routing Overhead vs. Pause time In addition, comparing to, our protocol also performs better in this aspect. This is not surprising since, instead of repairing the partially broken main route, always reconstructs a new main route from scratch when one is broken. As a result, every time a main route is broken, the main route request broadcast packets are flooded to the network. On the other hand, our protocol would try to repair the main route by taking advantage of the neighboring nodes that are close to the main route. The scope of repair query packet broadcast is thus effectively restricted within two-hops from the original main route. 3.4 Packet Latency The packet latency is measured by the average data packet delivery delay per route in our simulation. In Figure 3, the simulated average delay time is illustrated. It is expected that our protocol would perform better than the. The reason for such speculation is based on the fact that instead of starting from scratch every time a route is broken, our protocol would try to repair the broken main route with some substitute route around the main link. As a result, our protocol can recover from link failure more quickly in half of cases (see table 1), which results to the low communication latency. As we can see, the results correspond exactly to what we expected. Average Delay Time (sec) Fig. 3. Packet Latency vs. Pause time 4. CONCLUSION In this paper, we present a new on-demand routing protocol that is able to quickly repair a link or node failure

5 International Journal of Engineering & Technology IJET-IJENS Vol: 11 No: with less communication overhead. Comparing to the other notable on-demand routing protocol, our protocol has a much higher successful data delivery rate than with approximately 25% less in communication overhead. In term of communication latency, our protocol also performs very well, especially when node mobility is higher REFERENCES [1] Siva Ram Murthy, C. and B. S. Manoj. Ad hoc Wireless Networks: Architectures and Protocols. 1 st Edition, Prentice Hall, USA, pp: 880, [2] Ehsan H, Uzmi ZA, Performance Comparison Of Ad Hoc Wireless Network Routing Protocols, Proceedings of INMIC, pp , Dec., [3] Abolhasan M, Wyosocki T, Dutkiewicz E, A review of routing protocols for mobile ad hoc networks, Journal of ad hoc networks 1: pp. 1-22, [4] Johnson D. B., Maltz D. A, Dynamic Source Routing in Ad-Hoc Wireless Networks, Mobile Computing Tomasz Imielinski and Hank Korth, chapter 5, pp , Kluwer Academic Publishers, [5] Perkins CE, Royer EM, Ad-Hoc on Demand Distance Vector Routing, Proc. of 2nd IEEE Wksp. Mobile Computer Applications, pp , [6] Haas Z, Pearlman M, The Performance of Query Control Schemes for the Zone Routing Protocol, Proc. of ACM SIGCOMM '98, Vancouver, [7] Joe I, Batseli SG, MPR-Based Hybrid Routing for Mobile Ad- Hoc Networks, Proceedings of the 27th Annual Conference on Local Computer Networks (LCN 02) IEEE Computer Society, pp. 7-12, [8] Stajmenovic I, Position Based Routing in Ad Hoc Networks, IEEE Commun. Magazine, Vol. 40, No. 7: pp , [9] Basagni S, Chiamtac I, Syrotiuk V. R., Woodward B. A., A Distance Routing Effect Algorithm for Mobility (DREAM), Proceedings of the 4th International Conference on Mobile Computing and Networking, Dallas, Texas, US, pp ,1998. [10] Stajmenovic I, Seddigh M, Zunic J., Dominating Sets And Neighbor Elimination Based Broadcasting Algorithms in Wireless Networks, IEEE Transactions on Parallel and Distributed Systems, Vol. 13, pp , January, [11] Mamoun Hussein Mamoun, Location Aided Hybrid Routing Algorithm for MANET, will be published in Int. Journal of Engineering& Technology IJET/IJENS, Vol. 11, No. 01, pp , Feb [12] Imielinski T, Navas J. GPS Based Geographic Addressing Routing and Resource Discovery, Communications of the ACM 42: pp , [13] Watanabe M, Higaki H., No-Beacon GEDIR: Location-Based Ad-Hoc Routing with Less Communication Overhead, International Conference on Information Technology (ITNG 07), pp , [14] L. Bajaj, M Takai, R. Ahuja, K. Tang, R. Bagrodia, M. Gerla, GloMoSim: A Scalable Network Simulation Environment, Computer Science Dept., University of California Los Angeles, it is available for download GloMoSim at: [15] J. Broch, D.A. Malt, D.B. Johnson, Y.C. Hu, and J. Jetcheva, A Performance Comparison of Multi-Hop Wireless Ad Hoc Network Routing Protocols, MOBICOM 98, pp , [16] S.R. Das, C.E. Perkins, E.M. Royer, Performance Comparison of Two On-demand Routing Protocols for Ad Hoc Networks, Proceeding INFOCOM, pp. 3-12, Bibliography Name: Dr. Mamoun Hussein Mamoun. Address: Faculty of Computer and Information Sciences, Mansoura University, Egypt. Education & Work experience: has completed B.S. degree in electrical and computer engineering from Military Technical Collage (Egypt) in June 1979, his M.S degree in electrical and computer engineering from Cairo University (Faculty of Engineering) in Oct and PhD degree in electrical and computer engineering from Cairo University (Faculty of Engineering) in Dec.1990.His research interests including Routing and Multicast for MANET. Presently he is working as Associate Prof. in Faculty of Computer and Information Sciences, Mansoura University, Egypt. Tel: