任課教授：陳朝鈞 教授 學生：王志嘉、馬敏修 Modified Reverse AODV Routing Algorithm using Route Stability in Mobile Ad Hoc Networks 出處：Multitopic Conference,INMIC 2008. IEEE International 23-24 Dec. 2008 Page(s):255 - 259 作者：Zarei.M.；Faez.K. ；Nya.J.M. 任課教授：陳朝鈞 教授 學生：王志嘉、馬敏修 2009/12/30

Outline Introduction Ad-Hoc On Demand Distance Vector Routing Protocol (AODV) Reverse AODV algorithm (RAODV) Modified Reverse Ad Hoc On Demand Distance Vector(MRAODV) routing algorithm Path Maintenance in MRAODV Routing Algorithm Simulation environment and results Conclusions

Introduction (1/4) Mobile ad hoc networks (MANET) consist of mobile platform which communicate with each other through wireless links, without any predetermined infrastructure. If the source and destination nodes are not within the transmission range of each other, then intermediate nodes would be served as intermediate routers for the communication between the two nodes. 2009/12/30

Introduction (2/4) Moreover, mobile platform moves autonomously and communicates via dynamically changing network. Frequent change of the network topology is a main challenge for many important topics 2009/12/30

Introduction (3/4) In this paper,we consider the Ad-hoc On-Demand Distance Vector Routing Protocol (AODV) that uses a demand-driven route establishment procedure. We present an optimized version of this algorithm namely Reverse AODV (RAODV). We also present our routing protocol namely Modified-RAODV (MRAODV) routing algorithm which it can be an extension for RAODV. 2009/12/30

Introduction (4/4) The MRAODV routing algorithm can present good performance for high mobility environments 2009/12/30

Ad-Hoc On Demand Distance Vector Routing Protocol (AODV) The Ad-hoc On-Demand Distance Vector outing Protocol (AODV), is one of more common routing algorithm in ad hoc networks and is based on the principle of discover routes as needed. AODV is a reactive algorithm that has some capabilities such as; low processing, memory overhead, low network utilization. AODV routing algorithm is a prominent method for building routes between network nodes. 2009/12/30

Ad-Hoc On Demand Distance Vector Routing Protocol (AODV) In AODV routing algorithm, the source node distributes a route request packet at the time when a path is needed to the destination node. The source node initiates path discovery by broadcasting a route request (RREQ) packet to its neighbors. 2009/12/30

Ad-Hoc On Demand Distance Vector Routing Protocol (AODV) The source node initiates path discovery by broadcasting a route request (RREQ) packet to its neighbors. The RREQ has following fields: When the intermediate nodes receive route reply packet (RREP), they update the forward route to the destination. The route reply packet contains the following fields: 2009/12/30

Ad-Hoc On Demand Distance Vector Routing Protocol (AODV) AODV protocol uses sequence numbers to determine the timeliness of each packet and to prevent creation of loops. AODV algorithm uses Route Error Message (RERR) route failures and link failures propagated by a RERR from a broken link to the source node of the corresponding route. 2009/12/30

Ad-Hoc On Demand Distance Vector Routing Protocol (AODV) When the next hop link breaks, RERR packets are sent by the starting node of the link to a set of neighboring nodes that communicate over the broken link with the destination. 2009/12/30

Reverse AODV algorithm (RAODV) AODV routing algorithm builds a single loop-free path to each other node on the network. One disadvantage of AODV and most on-demand routing protocols is a route reply message loss. In route discovery phase, a route reply message (RREP) of AODV obtains by the spending cost of flooding the entire network or a partial area. 2009/12/30

Reverse AODV algorithm (RAODV) Route request packet in RAODV like AODV contain following fields where, the source and destination addresses, together with the broadcast ID, uniquely identify this RREQ packet. 2009/12/30

Fig.1 2009/12/30

Reverse AODV algorithm (RAODV) When the destination node receives first route request message, it generates reverse request (R-RREQ) message and broadcasts it to neighbor nodes within transmission range. 2009/12/30

Fig.2 2009/12/30

Reverse AODV algorithm (RAODV) When broadcasted reverse request packet arrives to intermediate node, it will check for redundancy. If it already received the same message, the message is dropped, otherwise forwards to next nodes and when the source node receives first reverse request message, then it starts packet transmission, and late arrived R-RREQs are saved for future use. 2009/12/30

Modified Reverse Ad Hoc On Demand Distance Vector(MRAODV) routing algorithm RAODV routing algorithm increases performance and when route fails occurs, the source node should select the best route between available routs. In this paper, we apply stability estimation method for rout selection and to increase performance. 2009/12/30

Modified Reverse Ad Hoc On Demand Distance Vector(MRAODV) routing algorithm RAODV algorithm solves this problem with selecting the rout with minimum length in available set of routes that have been already found. In our proposed routing algorithm (MRAODV), when a source node wants to communicate with a destination node, first it broadcasts a RREQ packet. 2009/12/30

Modified Reverse Ad Hoc On Demand Distance Vector(MRAODV) routing algorithm When destination receives a RREQ message, it broadcasts R-RREQ message to find source node. Each intermediate node which receives the R-RREQ message, calculates route stability by equation (2) and the route stability for each router is calculated by the following equation. 2009/12/30

Modified Reverse Ad Hoc On Demand Distance Vector(MRAODV) routing algorithm 2009/12/30

Modified Reverse Ad Hoc On Demand Distance Vector(MRAODV) routing algorithm When source node receives R-RREQ, it will have multiple routes to destination, so it selects stable route to destination node. This process is illustrated in figure 3. 2009/12/30

Modified Reverse Ad Hoc On Demand Distance Vector(MRAODV) routing algorithm According to this figure when one intermediate node moves and causes link breaks then active route fails and a new route must be selected. In AODV, this process is done by initializing route discovery procedure and in RAODV with selecting one available route with minimum hop count. In MRAODV, a new route with maximum stability is selected between available routes. 2009/12/30

Path Maintenance in MRAODV Routing Algorithm When a route established between source and destination, data transmission stage can be started. In high mobility environments, link failure is a common phenomenon which can be occurred. 2009/12/30

Path Maintenance in MRAODV Routing Algorithm In both reverse RAODV and AODV routing algorithms, source node selects new path based on shortest path method and when mobile node moves quickly, these algorithms can not show good performance. 2009/12/30

Simulation environment and results(1/2) We used the ns-2 simulator to implement our routing algorithm for comparison with RAODV and AODV routing algorithms and to check the effectiveness of the proposed method. For evaluation of MRAODV routing algorithm performance, we used two metrics: Packet Delivery Ratio Control Packet Overhead 2009/12/30

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Conclusions(1/2) This paper presented a new protocol for mobile ad hoc networks based on link stability and reverse packet transmission. We changed RAODV routing algorithm and made an optimized version of AODV. 2009/12/30

Conclusions(2/2) According to the simulation results, this algorithm is better than other version of AODV algorithm. We compared our method with AODV and RAODV routing algorithm in average to end delay and packet delivery ratio . We found that the presented protocol is suitable for high mobility rate environment and it shows a good performance when the number of nodes increases. 2009/12/30