I. INTRODUCTION:

A mobile ad hoc network (MANET) comprises of wireless nodes that move independent of each other forming a dynamically changing distributed resource-constrained system. The wireless nodes are often limited in their transmission range and multi-hop routing is a common phenomenon that has been of significant interest. There are several application domains in which MANETs have been deployed. These include: disaster recovery, military operations in a battlefield, outdoor entertainment activities, crowd control, conferences, and etc. One-to-many multicast communication is a characteristic feature of all these Application ns. Several multicast routing protocols have been proposed in the literature to support these MANET applications.

Depending on the underlying topology used for communication, the multicast protocols are mainly classified as: tree-based and mesh-based protocols. In tree-based protocols, only one route exists between a source and a destination and hence these protocols are efficient in terms of the number of link transmissions.

There are two major categories of tree-based protocols: source tree-based (the tree is rooted at the source) and shared tree-based (the tree is rooted at a core node and all communication from the source nodes to the receiver nodes is routed through this core node). Even though shared tree-based multicast protocols are more scalable with respect to the number of sources, these protocols suffer under a single point of failure, the core node. On the other hand, source tree-based protocols are more efficient in terms of traffic distribution. The source tree-based protocols are further classified into the following sub-categories: (i) Minimum hop-based, (ii) Minimum link based, (iii) Stability-based, and (iv) Zone-based protocols. The shared tree-based multicast protocols are further classified into: (i) Cluster-based, (ii) Session-specific, and (iii) IP multicast session-based protocols. In mesh-based multicast routing, multiple routes exist between the source node and each of the receivers of the multicast group. A receiver node receives several copies of the data packets, one copy through each of the multiple paths. Mesh-based multicast routing protocols provide robustness in the presence of node mobility; however, at the expense of a larger number of link transmissions leading to inefficient bandwidth usage. The mesh-based protocols are classified into source-initiated and receiver-initiated protocols depending on the entity (the source node or the receiver nodes) that initiates mesh formation. In this paper, we review widely studied, characteristic, representative multicast routing protocols for each of the above sub-categories and explain the salient features of the particular sub-categories through these protocols. We discuss the pros and cons of each of these multicast routing protocols and the categories to which they belong. A classification tree of the different categories and their representative multicast routing protocols that would be discussed in the paper is given in Figure 1.

Figure 1: Topology-based Classification of MANET Routing Protocols

II. MULTICAST ROUTING:

In this section, we briefly describe routing protocols in ad hoc networks. Then, we focus particularly on multicast routing since it is the focal point of the study undertaken in this work. We find in the literature many classifications. The first one reflects the existence of three main categories based on the routing strategy. Firstly, there are protocols, which use a proactive approach to find routes between all source destination airs regardless of the need of such routes. Examples of this approach are⁷ Destination-Sequence-Distance-Vector (DSDV) protocol, Wireless Routing Protocol (WRP), Global State Routing (GSR) protocol, Fishey State Routing (FSR) protocol. Landmark Ad hoc Routing (LANMAR) and Optimized Link State (OLSR) protocols recently proposed by the MANET group also falls in this category. Secondly, there are the reactive (on demand) routing protocols suggested with the key motivation of reducing routing load. DSR follows this approach. Other examples of this approach are⁷ Signal stability Routing (SSR), Associativity Based Routing (ABR), and Temporally Order Routing Algorithm (TORA). In addition to the above-mentioned protocols, hybrid protocols combine reactive and proactive characteristics, which enable them to adapt efficiently to the environment evolution. This approach comprises Zone Routing Protocol (ZRP)⁷. Routing protocols can also be classified in terms of an architectural view. A third classification is according to the location characteristics.

Multipoint communication has emerged as one of the most research areas in the field of networking. As the technology and popularity of Internet grow, applications, such as video conferencing, that require multicast support are becoming more widespread. Multicast protocols used in static networks as Distance Vector Multicast Routing Protocol (DVMRP), Multicast Open Shortest Path First (MOSPF), Core Based Trees (CBT), and Protocol Independent Multicast (PIM) do not perform well in wireless ad hoc networks due to the fragile multicast tree structures, which must be readjusted as connectivity changes. Furthermore, multicast trees usually require a global routing substructure such as link state or distance vector. The frequent exchange of routing vectors or link state tables, triggered by continuous topology changes, yields excessive channel and processing overhead. Hence, the tree structures used in static networks must be modified, or a different topology between group members need to be deployed for efficient multicasting in wireless ad hoc networks⁸. To provide efficient multicast routing in MANETs, a different kind of protocols should be designed. These protocols should modify the conventional tree structure, Some technical challenges of multicast routing are as follows¹⁰: minimizing network load, providing basic support for reliable transmission, designing optimal routes, providing robustness, efficiency, active adaptability, and unlimited mobility.

Because of the complexity of multicast routing in ad hoc networks, only a few propositions have been made. Globally, we notice two main categories, tree-based protocols (e.g. MAODV, ABAM, MZR [7], SMBP⁷) and mesh-based protocols (e.g. ODMRP, PatchODMRP).

The multicast extension of Ad Hoc On Demand Distance Vector (MAODV) routing protocol¹¹ uses destination sequence number for each multicast entry requiring a lot of control messages. The On-Demand Multicast Routing Protocol (ODMRP)¹² is based on a mesh structure for connecting multicast members using the concept of forwarding group nodes. ODMRP uses shortest path as a criteria to select forwarding group nodes, which is not the optimal route in a dynamic network as ad hoc network. PatchODMRP¹³ extends the ODMRP providing a more efficient way to deal with small number of multicast sources and high mobility. However, it still considers the shortest path criteria. Associativity-Based Multicast

Routing (ABAM) protocol¹⁴ has been advocated to improve routing performance, based on choosing more stable routes. However, this method could not avoid frequent rerouting due to nodes’ mobility. Obviously, multicast routing is a young research domain, no standard has been adopted yet and many issues have to be addressed and more studies are needed. Actually, most existing multicast protocols face several problems in tree maintenance and frequent reconfiguration when link failures occur. These protocols depend on upstream and downstream nodes requiring storage and control overhead. Moreover, some protocols consider the shortest path as a criterion for path selection, which is not usually suitable to the high and unpredictable variation of the topology. In this context, we propose a new on-demand multicast routing protocol, named Source Routing-based Multicast Protocol (SRMP). This protocol constructs a mesh to connect group members thus providing robustness against mobility. Multicast routes and group memberships are obtained on-demand to use efficiently network resources.

III SOURCE-TREE BASED MULTICAST PROTOCOLS:

In this section, we describe a representative protocol from each of the following major categories of source-tree based multicast routing protocols: (i) Minimum hop-based, (ii) Minimum link-based, (iii) Stability-based, and (iv) Zonebased protocols.

3.1 Minimum-hop based Multicast Protocols:

The minimum hop-based multicast routing protocols aim for a minimum hop path between the source node and every receiver node that is part of the multicast group. Each receiver node is connected to the source node on the shortest (i.e., the minimum hop) path and the path is independent of the other paths connecting the source node to the rest of the multicast group. The Multicast extension to the Ad hoc Ondemand Distance Vector (MAODV) protocol [25] is a classical example of minimum hop-based multicast routing protocols for MANETs. In this sub-section, we describe the working of MAODV in detail.

Tree Formation (Expansion) Phase: In MAODV, a receiver node joins the multicast tree through a member node that lies on the minimum hop path to the source. A potential receiver wishing to join the multicast group broadcasts a Route-Request (RREQ) message. If a node receives the RREQ message and is not part of the multicast tree, the node broadcasts the message in its neighborhood and also establishes the reverse path by storing the state information consisting of the group address, requesting node id and the sender node id in a temporary cache. If a node receiving the RREQ message is a member of the multicast tree and has not seen the RREQ message earlier, the node waits to receive several RREQ messages and sends back a Route-Reply (RREP) message on the shortest path to the receiver. The member node also informs in the RREP message, the number of hops from itself to the source. The prospective receiver receives several RREP messages and selects the membe rnode which lies on the shortest path to the source. The receiver node sends a Multicast Activation (MACT) message to the selected member node along the chosen route. The route from the source to receiver is set up when the member node and all the intermediate nodes in the chosen path update their multicast table with state information from the temporary cache.

Working Example: In Figure 2, we illustrate tree formation (expansion) under the MAODV protocol using an example. Here, the multicast tree is already established between the source node S and the two receivers R1 and R2 of the multicast group. A node is considered a multicast tree node if it is a source, receiver or an intermediate node of the multicast tree. Now, consider a new member node R3 joining as the receiver of the multicast group. To become part of the multicast tree, R3 broadcasts a Route Request (RREQ) control packet to its neighbors. If a neighbor node is a multicast tree node, it does not further propagate the RREQ packet; otherwise, it broadcasts the packet to its neighbors. The multicast tree node that receives a RREQ packet waits for a certain time period to receive any more RREQ packets and then responds back with a Route Reply (RREP) packet on the shortest (minimum hop) path to the initiator (R3). In the RREP packet, the tree node also includes the number of hops between itself and the source. In our example, intermediate tree node I1 (on the shortest path from S to R2) and the receivers R1 and R2 respond back with RREP packets to R3. The number of hops on the shortest path from R3 to each of R1 and R2 is 4; whereas the number of hops from I1 to R3 is 3. Also, the number of hops from S to R1 and R2 on the shortest path is respectively 2 and 3; whereas, the number of hops from S to I1 is 1. Considering all these, the shortest path from R3 to the source S would be the path that goes through the intermediate tree node I1. Hence, R3 decides to join the multicast tree through I1 and sends a Multicast Activation (MACT) message to I1. The intermediate nodes I5 and I8 that forwarded all of the three control packets (RREQ, RREP and MACT) now become part of the multicast tree.

Tree Maintenance Phase: Tree maintenance in MAODV is based on the expanding ring search (ERS) approach, using the RREQ, RREP and MACT messages. The downstream node of a broken link is responsible for initiating ERS to issue a fresh RREQ for the group. This RREQ contains the hop count of the requesting node from the multicast source node and the last known sequence number for that group. It can be replied only by the member nodes whose recorded sequence number is greater than that indicated in the RREQ and whose hop distance to the source is smaller than the value indicated in the RREQ.

IV SOURCE-INITIATED MESH-BASED MULTICAST:

Protocols:

A mesh is a set of nodes in the network such that all the nodes in the mesh forward multicast packets via scoped flooding¹⁴. As stated before, mesh-based protocols are more robust to link failures than tree-based protocols. Mesh based protocols can be either source-initiated or receiver initiated. In most of the cases, the forwarding mesh in source-initiated protocols is a union of per-source meshes, while receiver-initiated mesh protocols form a single shared mesh for all the sources. In this section, we discuss the source-initiated mesh based multicast routing protocols and in the next section, we discuss the receiver-initiated mesh based protocols. In the category of source-initiated meshbased multicast routing protocols, we discuss the well known On-Demand Multicast Routing Protocol (ODMRP) along with its extensions to handle high mobility and low node density (i.e., sparse networks), and the Neighbor Supporting multicast Mesh Protocol (NSMP).

4.1 On-Demand Multicast Routing Protocol (ODMRP):

ODMRP¹⁶ is a mesh-based multicast routing protocol based on the notion of a forwarding group (shown in Figure 3) – a set of nodes that forward data on the shortest paths between any two multicast members^2,6. Multicast group membership and routes are established and updated by the source in an on-demand basis. This leads to reduction in channel/ storage overhead and an increase in scalability. A soft-state approach is used for mesh maintenance and member nodes are not required to explicitly send leave messages while quitting a group. A performance comparison of the major ad hoc multicast routing protocols in¹⁷ shows ODMRP to be the most advantageous and preferred protocol in mobile wireless networks. ODMRP can also operate independently as an efficient unicast routing protocol. ODMRP operates through a request phase and a reply phase. Multicast sources, which are not aware of the routes or membership, broadcast a Join-Data packet. When a node receives the Join-Data packet for the first time, it updates its routing table by storing the upstream node id (backward learning process) and rebroadcasts the packet. Upon receiving a non-duplicate Join-Data packet, a multicast receiver creates and broadcasts a Join-Reply packet in its neighborhood. When a node receives the Join-Reply packet, it checks if it is listed as the next node ID in the packet. If so, the node is located on the path to the source and becomes part of the forwarding group. A FG (forwarding group) flag is set in its routing table and the node broadcasts its own Join-Reply packet. Likewise, the Join-Reply packet gets forwarded by the FG member nodes until it reaches the multicast source on the shortest path. As a result of this sou rce-receiver route construction and update process, a mesh of nodes referred to as the forwarding group is built. ODMRP makes use of the IEEE 802.11 MAC protocol to reliably transmit the Join-Reply packets that are critical to establishing and refreshing the forwarding groups and the associated multicast routes. Once the forwarding group is established and multicast routes are constructed, a source node sends down data packets to the receivers¹⁶. To leave a multicast group, the source node and receiver nodes can respectively stop sending the Join-Query and Join-Reply packets meant for that group. If a FG member node does not receive a Join-Reply packet before a timeout period, the node demotes itself to a non-forwarding node of the mesh. The performance of ODMRP heavily depends on the values selected for the route refresh interval and the FG timeout interval¹⁶. With small route refresh interval, there will be frequent broadcast of fresh route and membership information that may lead to a deluge of packets causing network congestion. On the other hand, if a larger route refresh interval is selected, nodes may not be aware of the latest route and multicast membership changes and this could lead to poor performance. The FG timeout value must be at least 3-5 times larger than the route refresh interval value. For networks with a heavy traffic load, a smaller value for the FG timeout interval will help to reduce redundancy of membership messages¹⁶; whereas, in the case of high mobility, a larger FG timeout value can make way for more alternative paths.

Figure 3. Concept of Forwarding Zone (adapted from²)

ODMRP based on Mobility Prediction: Since ODMRP requires periodic flooding of JOIN-QUERY messages to refresh routes and group membership, finding an optimal refresh interval is critical for its performance. An improved version of ODMRP is proposed in² that adapts the refresh interval to mobility patterns and speeds. The duration of time the routes will remain valid is predicted using the location and mobility information provided by Global Positioning System (GPS)¹². Using the predicted time of route disconnection, Join-Query messages are sent only when there are imminent route breaks of ongoing data sessions². The prediction method used in², originally proposed in²⁷, assumes a free-space propagation model, in which the received signal strength solely depends on its distance to the transmitter. Also, all nodes in the network are assumed to have their clocks synchronized using the network time protocol (NTP) or the GPS clock itself. With all these assumptions, if the motion parameters of two neighbors (e.g., speed, direction and radio propagation range) are known, the duration of time the two nodes will remain connected can be determined²⁷. Let two mobile nodes i and j be within the transmission range r of each other. Let (xi,yi) and (xj,yj) be the co-ordinates of i and j respectively. Let vi and vj be the speeds and θ (0 < θ i, θ j < 2π) be the moving directions of i and j respectively. The amount of time, the two nodes will remain connected is predicted²⁷ as:

The structure of the Join-Query and the Join-Reply packets need to be slightly modified to accommodate the information derived from mobility prediction. The Min-LET (minimum link expiration time) value field in the Join-Query packet indicates the minimum expiration time of the links traversed by the packet, starting from the source. The Min- LET value set by the source in the Join-Query packet is the Max-LET value (theoretically ∞), as the source is not connected to any upstream node. An intermediate node, upon receiving a non-duplicate Join-Query packet, will predict the LET of the link with the immediate upstream sender of the packet, and set the Min-LET value in the packet to be the minimum of its current value and the predicted LET. The same procedure is followed at the member nodes too and the final value of Min-LET in the Join-Query packet is referred as to the Route Expiration Time (RET) of the path from the source to the receiver node. A member node waits for a certain time before responding back with a Join-Reply packet. If more than one Join-Query packet is received, the member node chooses the (stable) path with the largest RET and sends a Join-Reply packet (with the RET value included) on this path. If a forwarding group node receives several Join-Reply packets, it chooses the path with the minimum RET and sends its own Join-Reply packet with the chosen RET value. After receiving Join-Reply packets across several paths, the source sets the predicted expiration time of the mesh to be the minimum of the RET values of these packets. The source starts sending data packets using the constructed stable mesh. Before the predicted mesh expiration time approaches, the source node floods a Join-Query packet. Some of the drawbacks of the mobility prediction technique is that if a node suddenly changes direction and/or speed, the predicted expiration time of the mesh and the RET values of the paths involving that node may be no longer valid. Also, since route and mesh construction is source initiated, a new receiver node wishing to become a multicast member, has to wait for the next sequence of Join-Query packets coming from the source. However, the performance of ODMRP has been reported to be significantly improved² with the use of mobility prediction. PatchODMRP: In ODMRP, the forwarding group (FG) for a multicast group is an aggregate of the per-source meshes. For multicast groups with fewer sources, the forwarding mesh will be sparsely populated and may require frequent reconfiguration using flooding of Join-Query packets. To handle this problem, the PatchODMRP protocol has been proposed in¹⁵, according to which whenever a FG member node sees the possibility of it getting separated from the mesh, it starts a patching procedure to reconnect itself to the mesh through a temporary path. With PatchODMRP, the Join-Query interval can be sufficiently long (the tradeoff is multicast group join latency for new receivers) even in the presence of high mobility. Simulation results in¹⁵ illustrate that for larger Join-Query intervals, the packet delivery ratio of PatchODMRP increases while that of the original ODMRP decreases. For a given degree of node mobility, the control overhead of PatchODMRP is 6 to 7 times lower than that of original ODMRP. The routing table at a FG node contains a HopCount field (not in the original ODMRP) specifying the hop count from the destination to the node and the field is updated when a FG node processes a Join-Query packet. The forwarding group table also contains two additional fields (compared to ODMRP): the Upstream FG nodes (has the next hop information) and Source list (list of multicast source nodes); these two fields are processed when an FG node processes the Join-Reply packets. When a node is no longer a neighbor, an FG node checks its forwarding group table whether the lost neighbor is in its Upstream FG nodes list. If an FG node loses connectivity to an upstream FG node, it initiates a local patching procedure by flooding an advertisement (ADVT) packet with a limited HopCount value (typically set to 2 or 3) for propagation. The ADVT packet contains the 3-field tuple {MGID, SrcAddr, SrcHopCount} where MGID, SrcAddr, SrcHopCount respectively refer to the multicast group ID, the multicast source address and the number of hops from SrcAddr to the initiator of the ADVT packet. When an FG node receives the ADVT packet, it checks whether it has a table entry for the MGID specified in the packet – if so, the FG node checks the value for the HopCount field in its routing table for the path from itself to the SrcAddr listed in the ADVT packet. If the HopCount value in the routing table is less than the SrcHopCount specified in the ADVT packet, it means that the FG node lies on a non-cyclic path from the initiator of the ADVT packet to the multicast source – SrcAddr. The FG node sends back a Patch packet to the initiator of the ADVT packet and the nodes located in the path traversed by the Patch packet become the new FG nodes of the multicast group. If any or all of the above conditions are not met, then the FG node decrements the HopCount field value in the ADVT packet by 1 and if the value is still above zero, the packet is broadcast to the neighbor nodes with the PreHopAddress set to the address of the FG node.

V. CONCLUSION:

In this survey, we reviewed various multicast routing protocols for MANETs. Most of the multicast routing protocols for MANETs are either mesh-based or tree-based. Tree-based protocols can be either shared-trees or per-source based shortest trees. Mesh protocols can be either source initiated (union of per-source meshes) or receiver-initiated (shared mesh). Tree-based protocols are efficient in data transmission while mesh-based protocols are robust to topology changes and are more stable than tree-based protocols. The routes chosen using tree-based protocols are fragile and require frequent reconfiguration. Each of the protocols discussed in this survey has its own advantages and disadvantages. An ideal protocol that satisfies all the requirements of MANETs is tough to design. For example, a protocol that aims at routing efficiency has to sacrifice for route robustness. Future research would involve a comprehensive simulation analysis of all of these representative multicast routing protocols in a discrete-event simulator and study their performance under identical scenarios. A lot of research papers that are currently available on performance comparison studies of MANET multicast routing protocols do not conduct a comprehensive simulation analysis of the different categories of multicast routing protocols (identified in this chapter) under identical scenarios. So, it is not easy to generalize the performance tradeoffs between the different categories and the representative multicast routing protocols. This could lead to development of more hybrid tree and mesh based protocols that could neutralize the tradeoffs and yield optimal performance simultaneously for more than one performance metric. Another potential research could be to study the behavior of these multicast routing protocols under different topology control graphs (e.g., Relative neighborhood graph, Gabriel graph, Yao graph and Delaunay triangulation)^3.25. Currently, the simulation studies available in the literature model the underlying network topology to be a unit disk graph wherein there is a link between any two nodes if the Euclidean distance between the two nodes is less than or equal to the transmission range of the nodes. While the unit disk graph model can yield significantly high network connectivity, each node will have a relatively larger number of neighbors. In a shared medium, typical of wireless networks, a larger neighborhood could severely drain the energy resources of a node as well as the network capacity due to the receipt of unintended packets and redundant transmissions. As the wireless nodes are battery charged, it is imperative to extend the operational lifetime of these devices as much as possible. Topology control is a potential solution to enhance the energy-efficiency and the capacity of the network. The focus of the topology control algorithms is to maintain the connectivity of the network with a reduced number of links as well as with a reduced transmission power per node (rather than the transmission power corresponding to the maximum transmission range) and thus optimize node lifetime.

VI. REFERENCES:

1. Life Time Assessment Based Routing Protocol for Mobile Ad Hoc Networks,” Proceedings of the IEEE International Conference on Communications, pp. 1697-1701, June 2000.

2. S. Bae, S. Lee, W. Su and M. Gerla, “The Design, Implementation, and Performance Evaluation of the Ondemand Multicast Routing Protocol in Multi-hop Wireless Networks,” IEEE Network, vol. 4, no. 1, pp. 70-77, August 2002.

3. N. Burri, P. Rickenbach, R. Wattenhofer and Y. Weber, “Topology Control Made Practical: Increasing the Performance of Source Routing,” Lecture Notes in Computer Science, vol. 4325, pp. 1 – 12, November 2006.

4. C. C. Chiang, M. Gerla and L. Zhang, “Shared Tree Wireless Network Multicast,” Proceedings of the 6thInternational Conference on Computer Communications and Networks, pp. 28-33, September 1997.

5. C. C. Chiang, H. K. Wu, W. Liu and M. Gerla, “Routing in Clustered Multihop, Mobile Wireless Networks with Fading Channel,” Proceedings of the IEEE Singapore International Conference on Networks (SICON), pp. 197- 211, April 1997.

6. C. C. Chiang, M. Gerla and M. Zhang, “Forwarding Group Multicast Protocol (FGMP) for Multi-hop, Mobile Wireless Networks,” Baltzer Cluster Computing, vol. 1, no. 2, pp. 187-196, 1998.

7. T. H. Cormen, C. E. Leiserson, R. L. Rivest and C. Stein, “Introduction to Algorithms,” 2nd Edition, MIT Press/ McGraw-Hill, September 2001.

8. S. Deering, D. L. Estrin, D. Farinacci, V. Jacobson, C.-G. Liu and L. Wei, “The PIM Architecture for Wide-Area Multicast Routing,” IEEE/ACM Transactions on Networking, vol. 4, no.2, pp. 153-162, April 1996.

9. J. J. Garcia-Luna-Aceves and E. L. Madruga, “The Coreassisted Mesh Protocol,” IEEE Journal on Selected Areas in Communications, vol. 17, no. 8, pp. 1380-1394, 1999.

10. M. Gerla, C. C. Chiang, and L. Zhang, “Tree Multicast Strategies in Mobile, Multi-hop Wireless Networks,” ACM/Baltzer Mobile Networks and Applications, vol. 4, no. 3, pp. 193-207, October 1999.

11. Z. J. Haas and M. R. Pearlman, “The Performance of Query Control Schemes for the Zone Routing Protocol,” IEEE/ACM Transactions on Networking, vol. 9, no. 4, pp. 427-438, August 2001.

12. B. Hofmann-Wellenhof, H. Lichtenegger and J. Collins,Global Positioning System: Theory and Practice, 5th ed., Springer, September 2004.

13. D. B. Johnson, “Routing in Ad Hoc Networks of Mobile Hosts,” Proceedings of the Workshop on Mobile Computing Systems and Applications, pp. 158-163, December 1994.

14. C. Y. Lee and H. K. Cho, “Multicast Routing Considering Reliability and Network Load in Wireless Ad hoc Networks,” Proceedings of the 53rd IEEE VTS Spring Vehicular Technology Conference, vol. 3, pp. 2203-2207, May 2001.

15. M. Lee and Y. Kim, “PatchODMRP: An Ad hoc Multicast Routing Protocol,” Proceedings of the 15th IEEE International Conference on Information Networking, pp. 537-543, January-February 2001.

16. S. Lee, M. Gerla, C. C. Chiang, “On-demand Multicast Routing Protocol,” Proceedings of the IEEE Wireless Communications and Networking Conference, vol. 3, pp. 1298-1302, 1999.

17. S. Lee, W. Su, J. Hsu, M. Gerla and R. Bagrodia, “A Performance Comparison Study of Ad hoc Wireless Multicast Protocols,” Proceedings of the 19th IEEE AnnualJoint Conference on Computer Communications, vol. 2, pp. 565-574, March 2000.

18. S. Lee and C. Kim, “Neighbor Supporting Ad hoc Multicast Routing Protocol,” Proceedings of the 1st Annual Workshop on Mobile and Ad hoc Networking and Computing, pp. 37-44, August 2000.

19. J. Moy, “Multicast Extensions to OSPF,” Request forComments: 1584, March 1994.

20. S. Murthy and J. J. Garcia-Luna-Aceves, “An Efficient Routing Protocol for Wireless Networks,” Mobile Networks and Applications, vol. 1, no. 2, pp. 183-197, October 1996.

21. T. Ozaki, J. B. Kim and T. Suda, “Bandwidth-Efficient Multicast Routing Protocol for Ad hoc Networks,” Proceedings of the 8th International Conference on Computer Communications and Networks, pp. 10-17, October 1999.

22. V. D. Park and M. S. Corson, “A Highly Adaptive Distributed Routing Algorithm for Mobile Wireless Networks,” Proceedings of the 16th Annual International Conference on Computer Communications, vol. 3, pp. 1405- 1413, April 1997

23. C. E. Perkins and P. Bhagwat, “Highly Dynamic Destination Sequenced Distance Vector Routing for Mobile Computers,” Proceedings of ACM (Special Interest Group on Data Communications) SIGCOMM, pp. 234-244, October 1994.

24. C. E. Perkins and E. M. Royer, “Ad Hoc On-demand Distance Vector Routing,” Proceedings of the 2nd Annual IEEE International Workshop on Mobile Computing Systems and Applications, pp. 90-100, February 1999.

25. E. Royer and C. E. Perkins, “Multicast Operation of the Ad-hoc On-demand Distance Vector Routing Protocol,” Proceedings of the 5th ACM/IEEE Annual Conference on Mobile Computing and Networking, pp. 207-218, Seattle, USA, August 1999.

Received on 05.12.2011 Accepted on 24.12.2011

Research J. Engineering and Tech. 3(1): Jan.-Mar. 2012 page 12-18