This paper presents a novel multicast routing protocol for mobile ad hoc wireless networks. The protocol, termed ODMRP (On-Demand Multicast Routing Protocol), is a mesh-based, rather than a conventional treebased, multicast scheme and uses a forwarding group concept (only a subset of nodes forwards the multicast packets via scoped flooding). It applies on-demand procedures to dynamically build routes and maintain multicast group membership. ODMRP is well suited for ad hoc wireless networks with mobile hosts where bandwidth is limited, topology changes frequently, and power is constrained. We evaluate ODMRP's scalability and performance via simulation.

The Core-Assisted Mesh Protocol (CAMP) is introduced for multicast routing in ad-hoc networks. CAMP generalizes the notion of core-based trees introduced for internet multicasting into multicast meshes that have much richer connectivity than trees. A shared multicast mesh is defined for each multicast group; the main goal of using such meshes is to maintain the connectivity of multicast groups even while network routers move frequently. CAMP consists of the maintenance of multicast meshes and loop-free packet forwarding over such meshes. Within the multicast mesh of a group, packets from any source in the group are forwarded along the reverse shortest path to the source, just as in traditional multicast protocols based on source-based trees. CAMP guarantees that, within a finite time, every receiver of a multicast group has a reverse shortest path to each source of the multicast group. Multicast packets for a group are forwarded along the shortest paths from sources to receivers defined within the group's mesh. CAMP uses cores only to limit the traffic needed for a router to join a multicast group; the failure of cores does not stop packet forwarding or the process of maintaining the multicast meshes.

This paper presents the On-Demand Multicast Routing Protocol (ODMRP) for wireless mobile ad

In this paper we propose a new multicast protocol for multihop mobile wireless networks. Instead of forming multicast trees, a group of nodes in charge of forwarding multicast packets is designated according to members' requests. Multicast is then carried out via "scoped" flooding over such set of nodes. The forwarding group is periodically refreshed to handle topology/membership changes. Multicast using forwarding group takes advantage of wireless broadcast transmissions and reduces channel and storage overhead, thus improving the performance and scalability. The key innovation with respect to wired multicast schemes like DVMRP is the use of flags rather than upstream/downstream link state, making the protocol more robust to mobility. The dynamic reconfiguration capability makes this protocol particularly suitable for mobile networks. The performance of the proposed scheme is evaluated via simulation and is compared to that of DVMRP and global flooding. Keywords: Wireless Network, Mu...

Wireless networks allow a more flexible model of communication than traditional networks since the user is not limited to a fixed physical location. Unlike cellular wireless networks, an ad hoc wireless network does not have any fixed communication infrastructure. For an active connection, the end host as well as the intermediate nodes can be mobile. Therefore routes are subject to frequent disconnections. In such an environment, it is important to minimize disruptions caused by the changing topology for critical application such as voice and video. This presents a difficult challenge for routing protocols, since rapid reconstruction of routes is crucial in the presence of topology changes. By exploiting non-random behaviors for the mobility patterns that mobile users exhibit, we can predict the future state of network topology and perform route reconstruction proactively in a timely manner. Moreover, by using the predicted information on the network topology, we can eliminate transmis...

Service discovery is an integral part of the ad hoc networking to achieve stand-alone and self-configurable communication networks. In this paper, we discuss possible service discovery architectures along with the required network support for their implementation, and we propose a distributed service discovery architecture which relies on a virtual backbone for locating and registering available services within a dynamic network topology. Our proposal consists of two independent components: (i) formation of a virtual backbone and (ii) distribution of service registrations, requests, and replies. The first component creates a mesh structure from a subset of a given network graph that includes the nodes acting as service brokers and a subset of paths (which we refer as virtual links) connecting them. Service broker nodes (SBNs) constitute a dominating set, i.e. all the nodes in the network are either in this set or only one-hop away from at least one member of the set. The second component establishes sub-trees rooted at service requesting nodes and registering servers for efficient dissemination of the service discovery probing messages. Extensive simulation results are provided for comparison of performance measures ,i.e. latency, success rate, and control message overhead, when different architectures and network support mechanisms are utilized in service discovery.

Multicasting has emerged as one of the most focused areas in the field of networking. As the technology and popularity of Internet grow, applications, such as video conferencing, that require multicast feature are becoming more widespread. Another interesting recent development has been the emergence of dynamically reconfigurable wireless ad hoc networks to interconnect mobile users for applications ranging from disaster recovery to distributed collaborative computing. In this article we describe the On-Demand Multicast Routing Protocol for mobile ad hoc networks. ODMRP is a mesh-based, rather than a conventional tree-based, multicast scheme and uses a forwarding group concept (only a subset of nodes forwards the multicast packets via scoped flooding). It applies on-demand procedures to dynamically build routes and maintain multicast group membership. We also describe our implementation of the protocol in a real laptop testbed. 1 Introduction An ad hoc network [1, 2] is a dyn...

Most of the multicast routing protocols for ad-hoc networks today are based on shared or source-based trees; however, keeping a routing tree connected for the purpose of data forwarding may lead to a substantial network overhead. A different approach to multicast routing consists of building a shared mesh for each multicast group. In multicast meshes, data packets can be accepted from any router, as opposed to trees where data packets are only accepted from routers with whom a "tree branch" has been established. The difference among multicast routing protocols based on meshes is in the method used to build these structures. Some mesh-based protocols require the flooding of sender or receiver announcements over the whole network. This paper presents the Core-Assisted Mesh Protocol, which uses meshes for data forwarding, and avoids flooding by generalizing the notion of core-based trees introduced for internet multicasting. Group members form the mesh of a group by sending join...

this paper, we extend the tree multicast concept to wireless, mobile, multihop networks for applications ranging from ad hoc networking to disaster recovery and battlefield. The main challenge in wireless, mobile networks is the rapidly changing environment. We address this issue in our design by: (a) using "soft state"; (b) assigning different roles to nodes depending on their mobility (2-level mobility model); (c) proposing an adaptive scheme which combines shared tree and per-source tree benefits, and; (d) dynamically relocating the shared tree Rendezvous Point (RP ). A detailed wireless simulation model is used to evaluate various multicast schemes. The results show that per-source trees perform better in heavy loads because of the more efficient traffic distribution; while shared trees are more robust to mobility and are more scalable to large network sizes. The adaptive tree multicast scheme, a hybrid between shared tree and per-source tree, combines the advantages of both and performs consistently well across all load and mobility scenarios. The main contributions of this study are: the use of a 2-level mobility model to improve the stability of the shared tree; the development of a hybrid, adaptive per-source and shared tree scheme, and; the dynamic relocation of the RP in the shared tree.

Shared Tree multicast is a well established concept used in several multicast protocols for wireline networks (eg. Core Base Tree, PIM sparse mode etc). In this paper, we extend the Shared Tree concept to wireless, mobile, multihop networks for applications ranging from ad hoc networking to disaster recovery and battlefield. The main challenge in wireless, mobile networks is the rapidly changing environment. We address this issue in our design by: (a) using "soft state"; (b) assigning different roles to nodes depending on their mobility (two level mobility model); (c) proposing an adaptive scheme which combines shared tree and source tree benefits. A detailed wireless simulation model is used to evaluate the proposed schemes and compare them with source based tree (as opposed to shared tree) multicast. Both uniform and 2-level mobility models are used in the comparison. The results show that shared tree protocols have low overhead and are very robust to mobility. In particular, the Ada...