COMPARATIVE STUDY ON OLSR, ZRP AND AODV PROTOCOL 1 SWAPNIL FADTE, 2VINEET JAIN 1 Computer Engineering, Goa College of Engineering, Farmagudi, Goa 2 Goa College of Engineering, Farmagudi, Goa Abstract- A mobile ad hoc Network is self configuring wireless of mobile device network. Each device is free to move independently in any direction , and at any time. However challenging task is that it has to maintain the information required to properly route traffic. It also maintains flexibility as long as node is connected. There are many routing protocols proposed such as OLSR, AODV, DSDV,DSR, ZRP, and TORA, LAR to improve the routing performance and reliability. In this work we describes the characteristics of ad hoc routing protocols OLSR, AODV and ZRP with help of performance metrics such as end–to–end delay, packet delivery ratio, throughput and jitter by increasing the number of nodes in the network. This comparative shows that OLSR, ZRP performs well in dense networks when there is low mobility and low traffic but in high mobility and high traffic environment ZRP performs well than OLSR and AODV. Keywords- AODV,OLSR, ZRP, MANETs, Survey, Routing Protocols. I. wireless networks deals with the process of managing energy resources by means of controlling the battery discharge, adjusting the transmission power, and scheduling of power sources. The modification is done in effect of power management issue in modified OLSR and existing OLSR routing protocol with the metrics like power consumes in all three modes transmit, received and ideal modes, TC message received, Hello message received, signal received and forward to MAC, signal received but with errors and power consumption have been used. INTRODUCTION The rapid increases in the applications of Personal Digital Assistants (PDAs) devices such as tabs, compact laptops etc has made popularity of wireless networks. One of the major types of wireless networks is Mobile Ad-Hoc networks (MANET). Every node in this network acts as a router or relay station to forward data to the designated node. In this network nodes are mobile and constantly change its location from one MANET to another. The application of this network is such as emergency situation, disaster recovery, crowd control, battle fields etc. Many routing protocols have been proposed for the mobile ad hoc network and classified as Proactive or Table Driven routing Protocol, Reactive or On Demand Routing Protocol, Hybrid Routing protocol. III. MANETS ROUTING PROTOCOLS A. Reactive protocols This routing is known as on- demand routing or source-initiated routing protocol. It imposes less overhead due to route messages on the network but at the same time, in route finding process it has high latency time and rarely excessive flooding of the communication packets may lead to network blockage. All nodes need not maintain up-to- date routing information here. Dynamic Source Routing (DSR) [1] , Adhoc On- Demand Distance Vector Routing (AODV) [4] and Temporally Ordered Routing Algorithm (TORA) [2], are some of the examples of reactive routing protocol. II. AD HOC PROTOCOLS FOR ROUTING NETWORK In most pioneering topics in computer communications is wireless networking. One area in wireless networking is mobile ad hoc networking. The concept of mobile ad hoc networking is based on the fact that users can communicate with each other in network, without any form of centralized administration. In a mobile ad hoc network, nodes are often powered by batteries. Every message can send and every computation performed drains the battery life. One solution for power conservation in mobile ad hoc network is power management. This means that routing decisions made by the routing protocol should be based on the power-status of the nodes. Nodes with low batteries will be less preferably for forwarding packets than nodes with full batteries, thus increasing the life of the nodes. A routing protocol should try to minimize control traffic, such as periodic update messages to improve the lifetime of the nodes and network. Power management in  Ad-Hoc on Demand Distance Vector Protocol: In this network node broadcast a request if it requires connection. Other nodes forward this message to needy node and records the node. When a node receives such a message and already has a route to the desired node, it sends a message backwards through a temporary route to the requesting node. The needy node uses the route that has the least number of hops through other nodes. Unused entries in the routing tables are recycled after a time. When a link fails, a routing error send to a transmitting node, and the process Proceedings of 3rd IRF International Conference, 10th May-2014, Goa, India, ISBN: 978-93-84209-15-5 90 Comparative Study on OLSR, ZRP and AODV Protocol repeats. Complexity of protocol is to lower the messages to conserve the capacity of network. This can be done by using sequence number and time to live. Since link-state routing requires the topology database to be synchronized across the network, OSPF and IS-IS perform topology flooding using a reliable algorithm. Such an algorithm is very difficult to design for ad hoc wireless networks, so OLSR doesn't bother with reliability; it simply floods topology data often enough to make sure that the database does not remain unsynchronized for extended periods of time. Advantages and Limitation The advantage of AODV is that it do not create extra traffic for communication along existing links []. Also, distance vector routing doesn't require much memory or calculation as it is simple. The connection setup delay is lower. However AODV requires more time to establish a connection, and to establish a initial route is heavier than some other approaches and if the source sequence number is very old, the intermediate nodes can lead to inconsistent routes. Also, multiple RouteReply packets in response to a single RouteRequest packet can lead to heavy control overhead. it consumes unnecessary bandwidth due to periodic beaconing. Advantages and Limitation OLSR is a flat routing protocol and it does not need central administrative system to handle its routing process. The link is reliable for the control messages, since the messages are sent periodically and the delivery does not have to be sequential. This protocol is best suitable for high density network and does not allows long delays in the transmission of the packets. B. Table Driven (Proactive ) protocols Proactive routing is also often termed as table- driven routing. In this routing protocols, lists of destinations and their routes are maintained by periodic distribution of routing tables throughout the network and this category of protocol always strives to maintain consistent and updated routing information at each node [3]. However, as a limitation this protocol needs that each node periodically sends the updated topology information throughout the entire network, this increase the protocols bandwidth usage. But the flooding is minimized by the MPR’s, which are only allowed to forward the topological messages. C. Hybrid Routing Protocol: Hybrid routing protocol combines the advantages of both proactive and reactive routing protocols. The routing is initially established with some proactively prospected routes and then it serves the demand from additionally activated nodes through reactive flooding. The existing hybrid protocols are ZRP. This protocols use link-state routing algorithms which frequently flood the link information about its neighbors and the main drawback of proactive routing protocol is that all the nodes in the network always maintain an updated table. DestinationSequenced Distance-Vector Routing Protocol (DSDV) [4] and Optimized Link-State Routing (OLSR) [5] are the two common proactive routing protocols.   Optimized Link State Routing Protocol: Linkstate routing protocols such as Open Shortest Path First (OSPF) [8] and IS-IS elect a designated router on every link to perform flooding of topology information. In wireless ad hoc network different approach is needed to optimize flooding process. Using Hello messages the OLSR protocol at each node discovers 2-hop neighbor information and performs a distributed election of a set of multipoint relays (MPRs). Nodes select MPRs such that there exists a path to each of its 2-hop neighbors via a node selected as an MPR. These MPR nodes then source and forward TC messages that contain the MPR selectors. This functioning of MPRs makes OLSR unique from other link state routing protocols in a few different ways: The forwarding path for TC messages is not shared among all nodes but varies depending on the source, only a subset of nodes source link state information, not all links of a node are advertised but only those that represent MPR selections. Zone Routing Protocol: If a packet's destination is in the same zone as the origin, the proactive protocol using an already stored routing table is used to deliver the packet immediately. If the route extends outside the packet's originating zone, a reactive protocol takes over to check each successive zone in the route to see whether the destination is inside that zone. This reduces the processing overhead for those routes. Once a zone is confirmed as containing the destination node, the proactive protocol, or stored route-listing table, is used to deliver the packet. In this way packets with destinations within the same zone as the originating zone are delivered immediately using a stored routing table. Packets delivered to nodes outside the sending zone avoid the overhead of checking routing tables along the way by using the reactive protocol to check whether each zone encountered contains the destination node. Thus ZRP reduces the control overhead for longer routes that would be necessary if using proactive routing protocols throughout the entire route, while eliminating the delays for routing within a zone that Proceedings of 3rd IRF International Conference, 10th May-2014, Goa, India, ISBN: 978-93-84209-15-5 91 Comparative Study on OLSR, ZRP and AODV Protocol would be caused by the route-discovery processes of reactive routing protocols. Table 2: Routing Performance in Low Mobility Performance OLSR ADOV ZRP Metrics End to End Low Average Low delay Packet delivery High High High ratio Throughput Good Average Average Jitter Low High High Table 3: Routing Performance in High Mobility Advantages and Limitation ZRP tries to combine the advantages of reactive and proactive routing protocols. With properly configured zone radius, ZRP may outperform both proactive routing protocols and reactive routing protocols. The potential disadvantage is that since hierarchical routing is used, the path to a destination may be suboptimal. Furthermore, since each node has higher level topological information, memory requirement is greater. IV. MATRICS COMPARISON FOR CONCLUSION We compared the characteristics of three different routing protocols which are of three different types i.e. reactive (AODV), proactive (OLSR) and hybrid (ZRP). ZRP is better compared to OLSR and AODV, as it is hybrid protocol. OLSR gives stable route and is suitable for dense networks where node needs to communicate with each other; they don’t have to find route as route is already calculated. AODV is efficient as it builds route when required but response to create route is higher compared to OLSR and ZRP. End to end delay of AODV protocol is higher than other two protocols in both low and high mobility scenario as it establishes route only when required. All three protocols are stable for finding routes hence packet delivery of all three are similar. Throughput of OLSR is better than other two protocols in both high and low mobility scenario as route is calculated beforehand. Jitter is also low in OLSR as it performs well in both low and high mobility. So we can conclude that no protocol is perfect, but selection of protocol should be application specific. PERFORMANCE A. End-to-end Delay: This metric represents average end-to-end delay andindicates how long it took for a packet to travel from the source to the application layer of the destination. It includes all possible delay caused by buffering during route discovery latency, transmission delays at the MAC, queuing at interface queue, and propagation and transfer time. It is measured in seconds. B. Packet Delivery Ratio: Packet delivery ratio is calculated by dividing thenumber of packets received by the destination through the number of packets originated by the application layer of the source (i.e. CBR source). It specifies the packet loss rate, which limits the maximum throughput of the network. C. Throughput: It is the measure of the number of packets successfully transmitted to their final destination per unit time. It is the ratio between the number of received packets vs sent packets. D. Packet Jitter: It is the ratio of transmission delay of the current packet and the transmission delay of the previous packet. Jitter can be calculated only if at least two packets have been received V. COMPARITIVE ADOV AND ZRP STUDY ON REFERENCES OLSR, Table 1: comparison of ad hoc routing protocols Performance OLSR ADOV ZRP Metrics End to End Low Average Low delay Packet delivery High High High ratio Throughput Good Average Average Jitter Low High High [1] David B. Johnson and David A. Maltz “Dynamic Source Routing in Ad Hoc Wireless Networks” Computer Science DepartmentCarnegie Mellon University 5000 Forbes Avenue Pittsburgh, PA 15213-3891 [2] http://en.wikipedia.org/wiki/Temporallyordered_routing_algorithm [3] Shah, R.C., Rabaey, J.:Energy Aware Routing forLow Energy Ad Hoc Sensor Networks. In: IEEE Wireless Communications and Networking Conference (WCNC 2002), vol. 1, pp. 350–355 (2002) [4] Perkins, C.E., Bhagwat, P.Highly Dynamic DestinationSequenced Distance-Vector Routing (DSDV) for Mobile Computers. In: SIGCOMM 1994, pp. 234–244 (August 1994) [5] Clausen, T., Jacquet, P.: Optimized link staterouting protocol, IETF RFC 3626 (2003), http://www.ietf.org/rfc/rfc3626.txt [6] http://en.wikipedia.org/wiki/List_of_ad_hoc_routing_protoc ols [7] http://en.wikipedia.org/wiki/Zone_Routing_Protocol [8] http://en.wikipedia.org/wiki/Open_Shortest_Path_First  Proceedings of 3rd IRF International Conference, 10th May-2014, Goa, India, ISBN: 978-93-84209-15-5 92