Stable and Reliable Route Identification Scheme for Efficient DSR Route Cache in Mobile Ad Hoc Networks
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Stable and Reliable Route Identification Scheme for Efficient DSR Route Cache in Mobile Ad Hoc Networks

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  • 1. IJASCSE Vol 1, Issue 3, 2012Oct. 31 Stable and Reliable Route Identification Scheme for Efficient DSR Route Cache in Mobile Ad Hoc Networks S. Sathish, K. Thangavel, M. Padmapriya, Assistant Professor, Professor, Research Scholar, Department of Computer Department of Computer Department of Computer Science, Science, Science, Periyar University, Salem, Periyar University, Salem, Periyar University, Salem, Abstract - Reactive routing protocol, rate in multi-radio range transmission DSR in MANET, discover routes based of mobile ad hoc network using NS-2 on demand with route cache random mobility model. The mechanism. DSR adapts source performance of the proposed SRRI routing and aggressive utilize of route scheme is measured in terms of caches. DSR lacks in determining reliable and stable routes for the ad route validity in route caches using hoc network, with node mobility rate, fixed time interval for cache bandwidth consumption, routing invalidation. Entry in cache is only for a overhead, packet delivery ratio. specified time and removed when time expired. Existing work presented a Keywords: MANET, DSR, Route dynamic mechanism to enhance cache Cache, SRRI strategies for reducing number of stale route entries and their dissemination I .INTRODUCTION with Expected Link Expiration Time (ELET) and updated route reply A mobile ad hoc network is a method is used to prevent mobile, multi-hop wireless network dissemination of stale routes. In with no stationary infrastructure. dynamically changing ad hoc mobile Dynamic topologies due to mobility scenario, route stability and the and limited bandwidth and battery reliability of the route becomes a major power make the routing problem in ad concern in DSR. However, existing hoc networks more challenging than work lacked in addressing the issues traditional wired networks. A key to of route stability and reliability factors. designing efficient routing protocols for The proposed work presents a Stable such networks lies in keeping the and Reliable Route Identification routing overhead minimal. A new class (SRRI) scheme for DSR protocol. of on-demand routing protocols (e.g., Route stability is achieved with node DSR, AODV, TORA) attempt to reduce transmission range control procedure. routing overhead by only maintaining Route reliability is maintained in terms routes between nodes taking part in of bandwidth requirement to discover data communication. In these the required route. In addition the protocols, the source discovers routes routing overhead for the bandwidth on-demand by initiating a route consumption is minimized with pre discovery process. cache history vector of route bandwidth maintained in node caches. A. Route Discovery in DSR Simulation is carried out with varied number of nodes and different mobility www.ijascse.in Page 1
  • 2. IJASCSE Vol 1, Issue 3, 2012Oct. 31 cache (Figure 2) rather than forwarding the route request. If the When a source node originates a new destination node receives the multiple packet addressed to a destination RREQ propagated from different node, it will search its Route Cache for routes, it replies to all RREQ by RREP. a source route. If no route is found in As a result of single route discovery to the cache, the sender initializes Route a destination node leads to multiple Discovery by broadcasting a Route routes for it. The RREP can be Request (RREQ) packet (Figure. 1), delivered to the initiator by simply containing destination node address, reversing the node list, by using a unique request identification, and an route to the initiator in its own cache, initial empty list which together or “piggybacking” the packet on a new uniquely identify this Route Discovery. Route Request to the original initiator. When the initiator receives the RREP, it adds the source route in its route cache for use in sending subsequent packets to the destination and for future use. Figure 1: Node N1 Sends RREQ B. Route Reply in DSR A node receiving the RREQ [1], if it is not the intended destination, appends its address to the node list and forwards the packet. However, Figure 2: Nodes N5, N3 Sends RREP first it checks whether it has recently seen another RREQ from the same C. Caching Mechanism source node with the same request identification and target address, or The majority of work related to whether its own address has already route caches in mobile ad hoc presented in the traveled node list of networks focused on Dynamic Source this RREQ. If either check is true, the Routing (DSR). DSR is an on-demand node silently drops this packet. When protocol that uses source routing and the RREQ packet reaches the makes aggressive use of route destination node, this node returns a caches. The current specification of Route Reply (RREP) to the source DSR lacks a mechanism to determine node (Fig. 2) with a copy of the node the validity of routes in the route list from the RREQ. If an intermediate caches. DSR uses fixed time interval node receiving the RREQ contains the for cache invalidation, i.e., entry in route to the destination in its Route cache appoints a fixed time and Cache then this node returns a RREP removed when time expired. This to the source node from its own route mechanism is not efficient as waiting too long to invalidate route introduces www.ijascse.in Page 2
  • 3. IJASCSE Vol 1, Issue 3, 2012Oct. 31 information and does not require any external support. stale route cache and its dissemination. Also not waiting long This paper has been organized enough removes the routes from as follow, section II describes the cache which are still valid and causes related work, section III describes the unnecessary retransmission of route proposed work, section IV illustrates request and route reply. The weakness the results and discussions and finally of this scheme is that it cannot adapt section V concludes the paper. to the change of the network topology. Because of these, setting the timeout close to the expected link expiration II. RELATED WORK time is considered to improve the performance. Since the actual lifetime In paper[5], the authors of a link highly depends on node proposes a novel MANETs routing mobility, to achieve good performance, protocol by using a link lifetime based dynamic caching schemes are desired. multipath mechanism to improve route stability, which is called Link lifetime D. Expected Link Expiration Time based Backup Routing protocol (LBR). During the local backup paths setup, Existing Work suggested LBR conduct a local optimization, scheme to develop and analyze which guarantees the backup path to enhanced cache strategies for have the maximum lifetime in local reducing number of stale route entries area. These mechanisms predict the and their dissemination. The basic timeout of a route cache using pre idea of the scheme is to use the determined parameters. However, Expected Link Expiration Time (ELET) predetermined value of timeout may [6] as its cache timeout and preventing work for certain scenarios but may not the distribution of stale information by work well for all. In [3], a smart packet updated route reply. The ELET is a is generated periodically which travels measure of time duration in which a through the network, collects topology node will become out of transmission information, and the nodes update range of another node. ELET is their route caches. Route entries then determined dynamically by the contain new routes reflecting the most Enhanced DSR (EDSR) when it recent topology changes. In [6] the receives RREQ from nearby node authors presented a cross-layer using the cross layer information. approach for predicting the route Cross layer design refers to protocol cache lifetime. The author assigns stack that intercommunicate the useful timeouts of individual links in route information to collectively achieve the cache by utilizing RSSI values desired optimization goal by allowing received from physical layer. This the different protocols to share scheme requires RSSI thresholds for information related to the network link timeout on every node of the ad status. Therefore, cross layer based hoc network. In this method the cache mechanism in which DSR timeout value directly depends on computes timeout value of individual thresholds value selected. In [4], the links by utilizing received signal authors developed a caching strategy strength from physical layer. This that permits nodes to update their method uses locally available network cache, when the topology of the network changes. To achieve it, all www.ijascse.in Page 3
  • 4. IJASCSE Vol 1, Issue 3, 2012Oct. 31 between strong and weak channels. Each channel is characterized as reachable nodes that have cached a strong or weak by the average signal broken link are notified when it fails. strength at which packets are Based on it, the proposed algorithm exchanged between the hosts at either notifies all reachable nodes that have end of the channel. In SRRI based cached the link in a distributed DSR route discovery, a source initiates manner. In this work, timeout for route a route discovery request when it has cache entry is not used, thus if nodes data to send to a destination which is become unreachable in some cases not in the routing table. The route- then they will not remove the stale search is broadcast to all neighboring route from their caches. hosts. These hosts propagate the broadcast if (1) it is received over a III. PROPOSED WORK strong channel and (2) the request has not been propagated previously (to Proposed work present a Stable avoid looping). The route-search and Reliable Route Identification packet stores the address of each (SRRI) scheme for DSR protocol in intermediate host in the route taken. extremely dynamic mobile node The destination chooses the route communication setting. Route stability recorded in the first arriving request, is accomplished with node since this route is probably shorter and transmission range control process, in less congested than routes for slower which transmission range of every arriving requests. The destination node in DSR cache is updated returns the route-reply along the occasionally to discover the node selected route, and each intermediate accessibility for link broadcast with node includes the new next-hop, other nodes. Route reliability is destination pairs in its routing table. sustained in terms of bandwidth requirement to determine the required route with enhanced DSR as is B. Reliability Based DSR Routing In justified in the existing work. MANET Furthermore the routing overhead for the bandwidth consumption is reduced In order to reduce the broadcast with pre cache account vector of route storm and routing overhead, an bandwidth preserved in node caches. intermediate node can re-broadcast a second RREQ packet only if it has A. Stability Based DSR Routing In higher reliability and stability than the MANET first RREQ packet, otherwise the RREQ will be discarded. When the first A new routing paradigm can be RREQ packet enabled reaches the obtained by considering the route destination node, the node starts the stability as routing metric. Stability timer interval and during that time it based routing aims at choosing routes examines the reliability and stability of which are more stable in time. The every arrived RREQ packet. When the Signal Stability based Routing timer interval expired, the destination performs on demand route discovery node selects the RREQ packet that by selecting longer-lived routes based has the highest QOS function and on signal strength and location sends the route reply (RREP) packet stability. The signal strength criteria carrying the route information to the allow the protocol to differentiate source node. When another RREQ www.ijascse.in Page 4
  • 5. IJASCSE Vol 1, Issue 3, 2012Oct. 31 bandwidth consumption is minimized with pre cache history vector of route packet with the same preference bandwidth maintained in node caches. arrives after the threshold time interval, it will not be considered and do not process it further. D. PROCEDURE FOR SRRI C. Stable and Reliable Route SRRI Procedure Identification (SRRI) Procedure SRRI (For each node We have developed an ad hoc from source to Destination) routing protocol by introducing a For Node 1 to Total Number Stable and Reliable Route of Nodes Do Identification (SRRI) scheme to the If GT = 1 & GR = 1 widely used DSR routing protocol. This routing metric is concerned with finding optimal paths between the source and the destination nodes that can avoid the congested regions in the network. Else It focuses on multiple objectives to be Error optimized, such as Bandwidth End If consumption (which refers to the End number of bits per second (bps) that can be sent along the path between For Node 1 to Total Number the source and the destination nodes) of Nodes Do and signal strength. In this modification, we include the local availability of the bandwidth End at a node in addition to the hop count End metric to maximize the end-to-end  TR  Transmission Range throughput in MANETs and at the  PT  Power of Transmitter same time to control the end-to-end  GT  Gain of Transmitter delay time. SRRI helps the routing protocol to determine the available  GR  Receiver Gain bandwidth at the node in order to  HT  Height of Transmitter improve the network performance by  HR  Height or Receiver avoiding routing traffic through the  D  Distance between two congested areas. consecutive nodes at time T Route stability is achieved with  L  Signal Loss node transmission range control  P  Power procedure, in which transmission  R  Success Rate range of every node in DSR cache is  T  Time updated periodically to identify the node availability for link transmission IV. RESULTS AND DISCUSSION with other nodes. Route reliability is maintained in terms of bandwidth We chose the popular network requirement to discover the required simulator NS2 as the simulator route with enhanced DSR as is primarily to implement methods explained in the existing work. In because it is widespread use in the addition the routing overhead for the academic community and the www.ijascse.in Page 5
  • 6. IJASCSE Vol 1, Issue 3, 2012Oct. 31 comprehensive manuals and tutorials that are freely available. It is possible to simulate a mobile multi-hop ad hoc wireless network in ns-2 using simulated 802.11 MAC layer. A. Packet Delivery Ratio Packet delivery ratio is the ratio of the Figure 4: Mobility Vs Routing Overhead number of data packets received by a destination over the number of data The above Figure 4 shows the packets delivered by the routing overhead of SRRI and ELET corresponding source. with different number of mobile nodes and mobility speeds, respectively. As shown in Figure 4 routing overhead increases as the number of mobile nodes or the mobility speed increases. The routing overhead for ELET is higher than SRRI. C. Bandwidth Consumption The number of packets can be sent along the path between the Figure 3: Mobility Vs Packet Delivery source and the destination nodes. Ratio These metrics was chosen due to these performance metrics was well The Figure 3 shows the packet known in showing the routing delivery ratio of SRRI and ELET with performance of the selected protocol. different number of mobility speeds. We can observe that SRRI transmits and receives more data packet than ELET. The ELET path may break easily. SRRI will always choose the most stable and reliable path, the chance of link breakage for SRRI is lower than ELET since ELET didn’t consider the stability of the selected path. B. Routing Overhead Routing Overhead can be termed as the total number of overhead packets Figure 5: Mobility Vs Bandwidth- is transmitted per second. This metric Consumption indicates the routing cost. The Figure 5 shows the bandwidth consumption of SRRI and ELET with different number of mobility www.ijascse.in Page 6
  • 7. IJASCSE Vol 1, Issue 3, 2012Oct. 31 REFERENCES speeds. As shown in Figure bandwidth [1] Johnson, D., Maltz, D., Hu, Y.-C, consumption increases as the number “The Dynamic Source Routing for of mobility speed increases. Bandwidth mobile ad hoc networks. IETF Internet consumption for ELET is higher than Draft (2004)”, SRRI. SRRI consumes less http://www.ietf.org/internetdrafts/ draft- bandwidth. This is because discovery ietf-manet-dsr-10.txt of reliable and stable path in SRRI based DSR. [2] Srivastava, V., Motani, M., “Cross- layer design: a survey and the road V. CONCLUSION ahead”, IEEE Communication Magazine 43(12), pp. 1112–1119, In this work, we have presented 2005 a new mechanism, Stable and Reliable Route Identification (SRRI) scheme for [3] Ashokraj, N., Arun, C., Murugan, K. DSR protocol in highly dynamic mobile “Route Cache Optimization node communication scenario. To Mechanism Using Smart Packets For reduce the stale cache information and On-Demand Routing Protocol in its dissemination, SRRI scheme MANET”, In International Conference dynamically computes the ELET and on Information Technology (ICIT), pp. adds this value when a route is 141–146, 2008. discovered by source node. SRRI considers with multiple constraints [4] Garrido, J., Marandin, D: A such as routing overhead, bandwidth, Linkcache Invalidation Mechanism for and signal strength to find the most Dynamic Source Routing (DSR) in Ad feasible route from the source node to Hoc Networks. In: 18th IEEE the destination node. It also selects the International Symposium on Personal, most stable links which leads to Indoor and Mobile Radio longer-lived routes and reduces route Communications, pp. 3–7 (2007) maintenance. The simulation results show that [5] Wen Jing Yang, Xinyu Yang, SRRI scheme can considerably Shusen Yang, Yage Gong, “Improving improve the performance. It achieved Route Stability In Mobile Ad Hoc the route stability and reliability with Networks Based On Link Lifetime”, node transmission range control Journal Of Communications, Vol. 6, procedure and bandwidth requirement. No. 3, May 2011. SRRI scheme attains data delivery ratio about 99.5 % in MANET. [6] Gaurav Bhatia , Vivek Kumar, “An Compared with ELET, proposed SRRI Enhanced DSR Caching Scheme scheme achieves 18% better result in Based on Cross Layer Information”, In Bandwidth consumption and 5% to 9% Springer-Verlag Berlin Heidelberg better result in Routing overhead. We 2011, pp. 191–203, 2011. can conclude that our proposed SRRI scheme provides the improvement in [7] The Network Simulator – ns-2, terms of data delivery ratio with lower http://www.isi.edu/nsnam/ns/. routing overhead and Bandwidth consumption for route reliability and stability in mobile ad hoc networks. www.ijascse.in Page 7