Abstract not found

In this paper, we present a Minimum Spanning Tree (MST) based topology control algorithm, called Local Minimum Spanning Tree (LMST), for wireless multi-hop networks. In this algorithm, each node builds its local minimum spanning tree independently and only keeps on-tree nodes that are one-hop away as its neighbors in the final topology. We analytically prove several important properties of LMST: (1) the topology derived under LMST preserves the network connectivity; (2) the node degree of any node in the resulting topology is bounded by 6; and (3) the topology can be transformed into one with bi-directional links (without impairing the network connectivity) after removal of all uni-directional links. These results are corroborated in the simulation study.

In this paper we investigate the performance of multicast routing protocols in wireless mobile ad hoc networks. An ad hoc network is composed of mobile nodes without the presence of a wired support infrastructure. In this environment, routing/multicasting protocols are faced with the challenge of producing multihop routes under host mobility and bandwidth constraints. In recent years, a number of new multicast protocols of different styles have been proposed for ad hoc networks. However, systematic performance evaluations and comparative analysis of these protocols in a common realistic environment has not yet been performed. In this study, we simulate a set of representative wireless ad hoc multicast protocols and evaluate them in various network scenarios. The relative strengths, weaknesses, and applicability of each multicast protocol to diverse situations are studied and discussed.

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

The use of on-demand techniques in routing protocols for multihop wireless ad hoc networks has been shown to have significant advantages in terms of reducing the routing protocol’s overhead and improving its ability to react quickly to topology changes in the network. A number of on-demand multicast routing protocols have been proposed, but each also relies on significant periodic (non-on-demand) behavior within portions of the protocol. This paper presents the design and initial evaluation of the Adaptive Demand-Driven Multicast Routing protocol (ADMR), a new ondemand ad hoc network multicast routing protocol that attempts to reduce as much as possible any non-on-demand components within the protocol. Multicast routing state is dynamically established and maintained only for active groups and only in nodes located between multicast senders and receivers. Each multicast data packet is forwarded along the shortest-delay path with multicast forwarding state, from the sender to the receivers, and receivers dynamically adapt to the sending pattern of senders in order to efficiently balance overhead and maintenance of the multicast routing state as nodes in the network move or as wireless transmission conditions in the network change. We describe the operation of the ADMR protocol and present an initial evaluation of its performance based on detailed simulation in ad hoc networks of 50 mobile nodes. We show that ADMR achieves packet delivery ratios within 1 % of a floodingbased protocol, while incurring half to a quarter of the overhead. 1.

Traditionally, reliable multicast protocols are deterministic in nature. It is precisely this determinism that tends to become their limiting factor when aiming at reliability and scalability, particularly in highly dynamic networks, e.g., ad hoc networks. As probabilistic protocols, gossip-based multicast protocols, recently (re-)discovered in wired networks, appear to be a viable means to “fight fire with fire ” by exploiting the nondeterministic nature of ad hoc networks. This paper presents a protocol that is designed to meet a more practical specification of probabilistic reliability; this gossipbased multicast protocol, called Route Driven Gossip (RDG), can be deployed on any basic on-demand routing protocol. RDG is custom-tailored to ad hoc networks, achieving a high level of reliability without relying on any inherent multicast primitive. We illustrate our RDG protocol by layering it on top of the “bare” DSR protocol. We prove the reliability and scalability of RDG through both analysis and simulation.

Nodes in mobile ad hoc networks communicate with one another via packet radios on wireless multihop links. Because of node mobility and power limitations, the network topology changes frequently. Routing protocols therefore play an important role in mobile multihop network communications. A recent trend in ad hoc network routing is the reactive on-demand philosophy where routes are established only when required. Most of the protocols in this category, however, use single route and do not utilize multiple alternate paths. In this paper, we propose a scheme to improve existing on-demand routing protocols by creating a mesh and providing multiple alternate routes. Our algorithm establishes the mesh and multipaths without transmitting any extra control message. We apply our scheme to the Ad-hoc On-Demand Distance Vector (AODV) protocol and evaluate the performance improvements by simulation.

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...

Group communication has become increasingly important in mobile ad hoc networks (MANET). Current multicast routing protocols in MANET have been shown to have large overhead due to dynamic network topology. To overcome this problem, there is a recent shift towards stateless multicast in small groups (DDM [1]). DDM queries the underlying unicast routing protocol to forward data packets towards members of a multicast group. The multicast distribution tree in DDM is implicit and cannot be controlled by the upper transport and application layers.

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...