ISSN: ISO 9001:2008 Certified International Journal of Engineering and Innovative Technology (IJEIT) Volume 2, Issue 8, February 2013

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1 An Inspection of Mobility Models Routine on Routing Protocols in Ad Hoc Network Sunil Kumar *a,b, Rahul Mishra a, Krishna Kumar a, Brij Mohan Singh b a Department of Computer Applications, IFTM University, Moradabad , India b Department of Computer Science & Engineering, COER, Roorkee, India Abstract-The Ad Hoc Networks are flexible, self configuring networks that do not require a fixed transportation. When these nets are simulated, mobility models can be used to specify node movements. The work in this paper focuses on designing a simulative study and investigation of mobility models performance with the use of routing protocols. In this paper the parameters used for assessment of packet delivery fraction (PDF), average end to end delay, and throughput. Some researchers have anticipated the results of extensive performance evaluation on several Ad Hoc mobility models environments with the use of routing protocols. The routing protocols and mobility models are discussed with respect to their applicability in real-life situation. NS-2.35 was used to produce the networks, services and situation personality. The intent of this current study is to estimate the performance of Mobility Models through routing protocols in Ad Hoc Network. Keywords: NS-2.35 simulator, Performance parameters, DSR, DSDV, AODV, Mobile Ad hoc Network, Mobility Model, BONNMOTION 2.0. I. INTRODUCTION Mobile Ad Hoc network is well known for its infrastructure less topology, due to the existence of free movement in Mobile Nodes (MNs) from one region to another, which is considered as a major source of deficit in ad hoc network. Ad hoc networks are composed of a set of mobile nodes known to communicate with one another over a common wireless channel [1, 2]. In compare to wired networks, nodes in an ad hoc network do not depend on exact communication shipping. Instead, they communicate either openly with each other or via intermediary nodes present in the network. The wireless and self configurable nature of ad hoc networks makes them well-suited for several scenarios such as mobile battle-fields, disaster relief, sensing and monitoring. However due to the lack of a capable communication infrastructure renders it to be a not easy and remarkable research area to explore and develop new designs of communication protocols for these networks [2, 3]. In this article, we have considered the effects of mobility models on the performance of routing protocols DSR, AODV (Reactive Protocol) and DSDV (Proactive Protocol). For experiment purposes, we have selected two mobility scenarios: Freeway and Manhattan models. These two Mobility Models are selected randomly and represent possibility of its practical application in future. Performance comparison has also been conducted across varying node densities and number of hops. In before experiment performed by some researchers exposed exponential difference of performance of the routing protocol with respect to different mobility models, node densities and length of data paths. In the second Part, we will study about the routing protocols for ad-hoc wireless networks can be right for use in our study. In the third Part, we will study mobility models used. In the fourth Part, we will run several simulation scenarios, taking into account the mobility models of the network. We will present the outcome from part three and calculate the performance of each tested mobility models with respect to protocols, based on the simulation results in the fifth parameters used for performance analysis result for simulations and finally, in sixth part we will conclude the paper. II. PROTOCOL USED A.DSDV (Destination Sequenced Distance Vector) It is one of the most well known table-driven routing algorithms for MANETs based on distance vector. In distance vector protocols, every node i maintains for each d5estination x a set of distances dij(x) for each node j that is a neighbor of i. Node i treats neighbor k as a next hop for a packet destined to x if dik(x) equals min j dij(x). The succession of next hops chosen in this manner leads to x along the shortest path. In order to keep the distance estimates up to date, each node monitors the cost of its outgoing links and periodically broadcasts to all of its neighbors its current estimate of the shortest distance to every other node in the network. The distance-vector which is periodically broadcasted contains one entry for each node in the network which includes the distance from the advertising node to the destination. The distance vector algorithm described above is a classical Distributed Bellman-Ford (DBF) algorithm. DSDV is a distance-vector algorithm which involves sequence numbers originated and updated by the destination, to avoid the looping problem caused by stale routing information. In DSDV, each node maintains a routing table which is constantly and periodically updated (not on-demand) and communicated to the associated neighbors. Each entry in the routing table shows the latest known configuration of destination sequence number. Each node periodically transmits updates, and it does so immediately when significant new information is available. The data broadcasted by each node will contain its new sequence number and the following information for each new route: the destination's address, the number of hops to reach the destination and the sequence number of the information received regarding that destination, as originally stamped by the destination. 269

2 No assumptions about mobile hosts maintaining any sort of time synchronization or about the phase relationship of the update periods between the mobile nodes are made. Following the traditional distance-vector routing algorithms, these update packets contain information about which nodes are accessible from each node and the number of hops necessary to reach them. Routes with more recent sequence numbers are always the preferred basis for forwarding decisions. Of the paths with the same sequence number, those with the smallest metric (number of hops to the destination) will be used [1, 6, 7]. As a proactive protocol it requires regular updates of its routing tables, which uses up battery power and a small amount of bandwidth even when the network is at its best. This limits the number of nodes that can join the network. Whenever topology of the network changes, a new sequence number is necessary before the network re-converges and DSDV is unstable until update packets propagate through the network. For this reason DSDV is not suitable for highly dynamic networks. DSDV is effective for creating ad-hoc networks for small populations of mobile nodes. Even if the number of nodes is higher, DSDV can perform well if the topology does not change quickly. Furthermore, as there is no need to ask for the route every time data needs to be sent its delay is insignificant. B DSR (Dynamic Source Routing Protocol) It is an on-demand protocol designed to restrict the bandwidth consumed by control packets in ad-hoc wireless networks by eliminating the periodic table-update messages required in the table-driven approach. As its name tells, this protocol use source routing algorithm to discover routes the major difference between this and the other on-demand routing protocols is that it is beacon-less and hence does not require periodic hello packet (beacon) transmissions, which are used by a node to inform its neighbors of its presence. The basic approach of this protocol during the route construction phase is to establish a route by flooding route request packets (RREQ) in the network. The destination node, on receiving a route request packet, responds by sending a route reply packet (RREP) back to the source, which carries the route traversed by the route request packet received. This is called route discovery and is one of its two major phases along with route maintenance. Route discovery and maintenance: - Consider a source node that does not have a route to the destination. When it has data packets to be sent to that destination, it floods a RREQ throughout the network. Each node, upon receiving a RREQ, rebroadcasts the packet to its neighbors if it has not forwarded it already, provided that the node is not the destination node and that the packet's time to live (TTL) counter has not been exceeded. To return the route reply, the destination node must have a route to the source node. If the route is in the Destination node's route cache, the route would be used. Otherwise, the node will reverse the route based on the route record in the RREP message header (this requires that all links are symmetric). Nodes can also learn about the neighboring routes traversed by data packets if operated in the promiscuous mode (the mode of operation in which a node can receive the packets that are neither broadcast nor addressed to itself). This route cache is also used during the route construction phase in the way that if an intermediate node that receives a RREQ has a route to the destination node in its own route cache, and then it replies to the source node by sending the RREP with the entire route information from the source node to the destination node. As each node can odd the other with a RREQ it seems that loops could be formed as well as multiple transmissions of the same RREQ, for example by an intermediate node that receives it through multiple paths. To prevent this, each RREQ carries a sequence number generated by the source node and the path it has travelled. A node, upon receiving a RREQ, checks the sequence number on the packet before forwarding it, so it is forwarded only if it is not a duplicate RREQ. In the event of serious transmission, the Route Maintenance Phase is initiated where by the route error packets (RERR) are generated at a node. That node sends to the others so they will remove the routes that uses that hop, so all routes containing it are truncated at that point. Again, the Route Discovery Phase is initiated to determine the most viable route. Advantages of DSR protocol are easily guaranteed loop-free routing, operation in net- works containing unidirectional links, use of only soft state in routing, and very quick recovery when routes in the network change. The DSR protocol is designed mainly for mobile ad-hoc networks of up to about two hundred nodes and is designed to work well even with very high rates of mobility. The main disadvantage of this protocol is that the route maintenance mechanism does not locally repair a broken link. Stale route cache information could also result in inconsistencies during the route reconstruction phase. Another important disadvantage is that a considerable routing overhead is involved due to the source routing mechanism employed in DSR. This routing overhead is directly proportional to the path length (even worse in IPv6). In the other hand, although its route discovers mechanism is really quick, the connection setup delay is higher than in table-driven protocols like DSDV [2, 3, 7]. C. AODV (Ad-Hoc on Demand Distance Vector) It is also an on-demand reactive protocol as well as DSR, where their major difference stems out from the fact that DSR uses source routing, in which a data packet carries the complete path to be traversed, however, in AODV, the source node and the intermediate nodes store the next-hop information corresponding to each how for data packet transmission, it uses distant vector routing algorithm This protocol also uses the messages RREQ (Route Request), RREP (Route Replies) and RERR (Route Errors) under UDP protocol and its method is almost the same as in DSR where 270

3 the source node floods the RREQ in the network when a route for a destination is not available. The major difference between AODV and other on-demand routing protocols is that it uses a destination sequence number (DSN) to determine an up-to-date path to the destination. A node updates its path information only if the DSN of the current packet received is greater than the last DSN stored at the node. A RREQ carries the source identifier (SrcID), the destination identifier (DestID), the source sequence number (SSN), the DSN, the broadcast identifier (BcastID), and the time to live (TTL) field. DSN indicates the freshness of the route that is accepted by the source. When an intermediate node receives a RREQ, it either forwards it or prepares a RREP if it has a valid route to the destination. The validity of a route at the intermediate node is determined by comparing the sequence number at the intermediate node with the destination sequence number in the RREQ. If a RREQ is received multiple times, which is indicated by the BcastID-SrcID pair, the duplicate copies are discarded. All intermediate nodes having valid routes to the destination, or the destination node itself, are allowed to send RREP packets to the source. Every intermediate node, while forwarding a RREQ, enters the previous node address and it s BcastID. A timer is used to delete this entry in case a RREP is not received before the timer expires. This helps in storing an active path at the intermediate node as AODV does not employ source routing of data packets. When a node receives a RREP, information about the previous node from which the packet was received is also stored in order to forward the data packet to this next node as the next hop toward the destination. All nodes active in the net transmit periodically hello messages (considered as special RREP messages). If one node does not receive hello from the neighbor means connection lost with them and they modify their routing table deleting that path. It also sends a RRER to the other neighbor nodes that used that path. It can be done easily because each node keeps a list of all the active nodes in each communication. The AODV routing protocol is considered for MANET with populations of tens to thousands of mobile nodes and can handle low, sensible and reasonably high mobility rates, as well as a variety of data travel levels. AODV has also been designed to decrease the dissemination of control traffic and eliminate overhead on data traffic in order to improve scalability and performance. Another main advantage of this protocol is that routes are recognized on demand and destination sequence numbers are used to and the latest route to the destination and the connection setup delay is lower. One of the disadvantages of this protocol is that intermediate nodes can lead to in-consistent routes if the source sequence number is very old and the intermediate nodes have a higher but not the latest destination sequence number, thereby having stale entries. Also multiple RREP packets in response to a single RREQ packet can lead to heavy control overhead. Another disadvantage of AODV is that the periodic beaconing leads to unnecessary bandwidth consumption. In the other hand, as a reactive distance-vector protocol, the connection setup delay is quite high and considerably more than in the case of other reactive protocols like DSR [3,7]. III. MOBILITY MODELS USED IN SIMULATIVE STUDY These portion presents the mobility models used in the simulation studies are presented, compared and explained free way and Manhattan Mobility Model. Different mobility models can be differentiated according to their measure of how two nodes are dependent in their motion. If two nodes are moving in same direction then they have high spatial dependency and measure of how current velocity, magnitude and direction are related to previous velocity. Nodes having same velocity have high temporal dependency [8]. Given below are the descriptions of mobility models. A. Freeway Mobility Models In this model emulates the motion behavior of mobile nodes on a freeway. It can be used in exchanging traffic status or tracking a vehicle on a freeway. Each mobile node is restricted to its lane on the freeway. The velocity of mobile node is temporally dependent on its previous velocity [7,8,9]. Given below is example topography showing the movement of nodes for freeway mobility model with seventy nodes, important characteristics in this model we can use maps. There are several freeways on the map and each freeway has lanes in both directions. The differences between random waypoint and freeway are the following: (1) Each mobile node is restricted to its lane on the freeway. (2) The velocity of mobile node is temporally dependent on its previous velocity. Formally, Vi (t+1) = Vi (t) + random () * ai (t) (3) If two mobile nodes on the same freeway lane are within the Safety Distance (SD), the velocity of the following node cannot exceed the velocity of preceding node. Formally, If j is ahead of i in its lane. Due to the above relationships, the Freeway mobility pattern is expected to have high spatial dependence and high temporal dependence. It also imposes strict geographic restrictions on the node movement by not allowing a node to change its lane. B. Manhattan Mobility Model Manhattan model emulate the movement pattern of mobile nodes on streets. It can be useful in modeling movement in an urban area.the scenario is composed of a number of horizontal and vertical streets. Given below is example topography showing the movement of nodes for Manhattan Mobility Model with seventeen nodes? The map defines the roads along the nodes can move. Important Characteristics: Maps are used in this model too. However, the map is 271

4 composed of a number of horizontal and vertical streets. The mobile node is allowed to move along the grid of horizontal and vertical streets on the map. At an intersection of a horizontal and a vertical street, the mobile node can turn left, right or go straight with certain probability. Except the above difference, the inter-node and intra-node relationships involved in the Manhattan model are the same as in the freeway model. It too imposes geographic restrictions on node mobility [8, 9, 13]. IV. SIMULATION CONSTRAINT Simulations have been carried out by the Network Simulator version 2.35 (NS2) [4]. Hardware and operating system (OS) configuration for performing simulations is specified in Table 2. The basic mobility scenario generation tool is BONNMOTION [5]. Table 1: Performance Parameters Parameter Value Channel type Wireless channel Simulator NS 2 (Version 2.35) protocols AODV,DSDV,DSR Simulation duration 300s Number of nodes 25,50,75 Transmission range Movement Model 250m MAC Layer Protocol Pause Time (s) Maximum speed 25 Minimum speed 0.5 Packet Rate Traffic type Data Payload Freeway, Manhattan 15 ± 3 s 4 packet/s CBR(Constant Bit Rate) 512 bytes/packet Max of CBR connections 10,20,40,60 Environment Size 900m * 900m For each simulation, the position and movements of the nodes are put randomly as well as the traffic among them. BONNMOTION is the accountable for the random properties of the positions and movements of the nodes and for the traffic NS-2.35 random variables are used. Setting the random variables accurately is a key point because if this is done wrong, some simulations can be associated and we can come up with bad results even if we think we have performed a sufficient amount simulation to describe a general case [11]. BONNMOTION 2.0 is the responsible to produce all movements information in tcl according to the mobility model selected. When they are generated, the movement patterns present a brief period so we have to be alert to skip this first seconds since they do not present the properties of the mobility model wanted. Each model must be checked or analyzed in order to see how much time is necessary to be skipped. Furthermore, according to [12], CBR traffic under UDP must be used to compare accurately the different protocols. TCP has a slow start mechanism that can manipulate the overall results. V. PERFORMANCE PARAMETERS AND RESULTS A. Performance Parameters The management of routing protocols is with the following significant Quality of Services (QoS) metrics for routine measures: 1 Packet Delivery Ratio (Pdr) Packet delivery ratio is an important metric as it describes the loss rate that will be seen by the transport protocols, which run on top of the network layer. Thus the packet delivery ratio in turn reflects the highest throughput that the network can support. It is defined in [9,10] as the ratio between the number of packets originated by the application layer Constant Bit Rate(CBR) sources and the number of packets received by the Constant Bit Rate(CBR) sink at the final destination[13,14]. It is the ratio of data packets delivered to the destination to those generated from the sources. It is calculated by dividing the number of packets received by destination through the number packet originated from the source. PDF = (Pr /Ps)*100 Where Pr is total Packet received & Ps is the total Packet sent. 2 Throughput It is the average number of messages successfully delivered per unit time number of bits delivered per second [10]. Throughput = (kbits/sec) Where N is the number of data sources. 3 Average End-to-End Delay This includes all possible delays caused by buffering during route discovery latency, queuing at the interface queue, retransmission delays at the MAC, and propagation and transfer times [9,10]. It is defined as the time taken for a data packet to be transmitted across an Ad Hoc from source to destination. D = (Tr Ts), Where Tr is receive Time and Ts is sent Time. B. Result Analysis Here in case of performance analysis we have consider above performance parameters. In Figure1, 2, 3, 4, 5, 6 the simulations are focusing in analyzing the performance on routing overhead, throughput and packet delivery ratio. The results also compared with two mobility models that we had chosen.the result will show the performance for mobility models with respect to protocols that had been selected under different mobility models, which is shown in fig Average end to end delays Fig 1: Average End to End Delay Vs Number Nodes for Freeway mobility model 272

5 Fig 2: Average End to End Delay Vs Number Nodes for Manhattan model 2. Packet delivery ratio (PDR) VI. CONCLUSION In this work, we have visualized the application of Mobile Ad-Hoc Routing protocols like AODV, DSDV and DSR for nodes. We have considered Manhattan and Freeway mobility models. The performance of a mobility models can vary significantly with different ad hoc network protocols. The experimental results illustrate the good performance of ad hoc network routing protocol with different mobility models. Per experimental results, the performance of the protocol is greatly affected by the mobility model. The performance of mobility models should be evaluated with the ad hoc network protocol that most closely matches the expected real-world scenario. In this paper comparison has been made on three parameters (a) PDR (b) Throughput (c) Average End to End delay. The routing protocols consider for this comparative study are AODV, DSDV and DSR. Manhattan mobility model is performed better as compare to free way mobility model on given parameters. Fig 3: Packet Delivery Ratio Vs Number Nodes for Freeway Mobility models Fig 4: Packet Delivery Ratio Vs Number Nodes for Manhattan Mobility models 3. Throughput Fig 5: Throughput Vs Number of Nodes for freeway mobility models Fig 6: Throughput Vs Number of Nodes for Manhattan mobility models REFERENCES [1] C. E. Perkins and P. Bhagwat, DSDV Routing over a Multi-hop Wireless Network of Mobile Computers [2] D. Johnson, Y. Hu, and D. Maltz, The dynamic source routing protocol (DSR) for mobile ad-hoc networks for IPv4", IETF, [3] C. Perkins, E. Belding-Royer, and S. Das, \ad-hoc on-demand distance vector (AODV) routing", IETF, 2003 [4] Network Simulator NS2 and Network Animator NAM. [Online].accessible: [5] M. Gerharz, C. de Waal, Bonn Motion - a mobility scenario generation tool, University of Bonn, [Online]. Accessible: [6] Sargolzaey H, Moghanjoughi AA, Khatun S. A review and comparison of reliable unicast routing protocols for mobile Ad-Hoc networks. Intern. J. Computer Sci. and Network Security. 2009: 9(1): [7] Kumar S, Sharma S C, Suman B. Mobility metrics based classification & analysis of mobility model for tactical network. Intern. J. Of next-generation networks. 2010: 2(3): [8] T. Camp et al., A Survey of Mobility Models for Ad Hoc Network Research, and Wireless Comm. & Mobile Computing: Special issue on Mobile Ad Hoc Networking: Research, Trends and Applications, vol. 2, pp , [9] Singh M, Singh D, Impact and Performance of Mobility Models in Wireless Adhoc Networks, Fourth Intern. Conference on Computer Sciences and Convergence Information Technology, 2009; [10] Arvind Kumar Shukla, C K Jha and Deepak Sharma. Article: The Efficiency Analysis of Mobility Model using Routing Protocols.IJCA Proceedings on International Conference on Advances in Computer Applications 2012 ICACA(1):6-10, September Published by Foundation of Computer Science, New York, USA. 273

6 [11] M. Umlauft and P. Reichl, Experiences with the ns-2 network simulator - explicitly setting seeds considered harmful", Proc. IEEE, [12] J. B. et al., A performance comparison of ad-hoc multi-hop wireless networks routing protocols", Proc. IEEE/ACM MOBICOM, [13] Medina A, Gursun G, Basu P, Matta I. On the Universal Generation of Mobility Models, in Proc. IEEE/ACM MASCOTS 2010, Miami Beach, FL, [14] Arvind Kumar Shukla, C K Jha and Deepak Sharma. Article: An Estimation of Routing Protocols in Mobility Models used for Ad Hoc Networks: Simulation Study. IJCA Proceedings on International Conference on Advances in Computer Application 2013 ICACA 2013:21-27, February Published by Foundation of Computer Science, New York, USA. Author Biography Sunil Kumar, MCA, Assistant Professor Department of Computer Applications, IFTM University, Moradabad, Uttar Pradesh, India. Dr. Brijmohan Singh, B.Tech, M.Tech, Ph.D, Associate Professor- Dept. of CSE, COER, Roorkee, Uttarakhand Technical University, Dehradun, Uttarakhand. 274