A clusterhead-token infrastructure for multihop, mobile wireless networks has been designed. Traditional routing algorithms in wireline networks are not feasible for mobile wireless environment due to the dynamic change in link connectivity. To gain better performance for clustered multihop, mobile wireless networks, routing must take into account radio channel access, code scheduling, and channel reservation. In this paper, we propose some heuristic routing schemes for clustered multihop, mobile wireless networks. A packet delay improvement up to fourfold has been observed in our simulations compared with shortest-pathscheme, making multimedia tra c viable. A radio channel model has been included to investigate the impact of channel fading on our protocols. To reduce the run time, a parallel simulator has been designed. Speedups of up to tenfold have been observed on a 16 processor SP/2.

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...

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.

In this paper we present a multicast protocol which builds upon a cluster based wireless network infrastructure. First, we introduce the network infrastructure which includes several innovative features such as: minimum change cluster formation; dynamic priority token access protocol, and; distributed hierarchical routing. Then, for this infrastructure we propose a multicast protocol which is inspired by the Core Based Tree approach developed for the internet. We show that the multicast protocol is robust to mobility, has low bandwidth overhead and latency, scales well with membership group size, and can be generalized to other wireless infrastructure. I. Introduction Wireless networks provide mobile users with ubiquitous communicating capability and information access regardless of location. In this paper we address a particular type of wireless networks called "multihop" networks. As a difference from "single hop" (i.e. cellular) networks [12] which require fixed base stations inte...

In this paper, we propose a multicast protocol for a multihop, mobile wireless network with cluster based routing and token access protocol within each cluster. The multicast protocol uses a shared tree which is dynamically updated to adjust to changes in topology and membership (i.e. dynamic joins and quits). Two options for tree maintenance have been simulated and evaluated: "hard state" (i.e. each connection must be explicitly cleared) and "soft state" (each connection is automatically timed out and must be refreshed). For the soft state policy, the performance of different choices of timeout and refresh timers is first analyzed for a range of node mobility values. Next, soft state and hard state policies are compared based on throughput, join delay, and control overhead criteria. Keywords : Routing, Multicast, Clustering, Multihop Wireless Networks, Hard state, Soft State Contact: Ching-Chuan Chiang (corresponding author) Computer Science Department, UCLA 405 Hilgard Avenue Los A...