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The hierarchical rendezvous point multicast (HRPM) protocol is a novel technique for improving the scalability of stateless multicast with respect to the group size. The technique is found to achieve significantly enhanced scalability and performance due to hierarchical organization and distributed hashing.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2007.03.006 Byline: Saumitra M. Das, Himabindu Pucha, Y. Charlie Hu Keywords: Geographic routing; Location services; MANETs; Scalability Abstract: Geographic routing protocols allow stateless routing by taking advantage of the location information of mobile nodes and thus are highly scalable. A central challenge in geographic routing protocols is the design of scalable distributed location services that track mobile node locations. A number of location services have been proposed, but little is known about the relative performance of these location services. In this paper, we perform a detailed performance comparison of three rendezvous-based location services that cover a range of design choices: a quorum-based protocol (XYLS) which disseminates each node's location to O(N) nodes, a hierarchical protocol (GLS) which disseminates each node's location to O(log N) nodes, and a geographic hashing-based protocol (GHLS) which disseminates each node's location to O(1) nodes. We present a quantitative model of protocol overheads for predicting the performance tradeoffs of the protocols for static networks. We then analyze the performance impact of mobility on these location services. Finally, we compare the performance of routing protocols equipped with the three location services with two topology-based routing protocols, AODV and DSR, for a wide range of network sizes. Our study demonstrates that when practical mobile ad hoc network (MANET) sizes are considered, the constants matter more than the asymptotic costs of location service protocols. In particular, while GLS scales better asymptotically, GHLS transmits fewer control packets and delivers more data packets than GLS in MANETs of sizes considered practical today and in the near future. Additionally, in contrast to the complex GLS design, the simplicity of GHLS provides significant resilience to performance degradation from mobility. Finally, although XYLS has a comparable packet delivery ratio to GHLS, it achieves this ratio with a higher overhead. Author Affiliation: Center for Wireless Systems and Applications in the School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, United States Article History: Received 26 March 2006; Revised 15 November 2006; Accepted 18 March 2007 Article Note: (miscellaneous) Responsible Editor: I. Stavrakakis

The Dynamics peer-to-peer (P2P) Source Routing (DPSR) protocol is proposed that imposes additional reuse of routes by exploiting the synergy between mobile ad hoc networks and peer-to-peer overlay networks. The simulations have shown that DPSR reduces the routing overhead from imposed route reuse when many nodes communicate with one or a few other nodes.

Mobile robot teams are particularly suited to many application scenarios where infrastructure is unavailable or damaged. For example, mobile robot teams can be useful for exploration in remote regions or search and rescue after a disaster. Localization of individual robots in these teams is essential for enabling many applications or improving the robot's performance in particular tasks. However, in infrastructure-less application scenarios, conventional techniques for localization have many disadvantages such as cost, deployment time, inaccuracy and energy use. Thus, there is a need for a localization scheme that works in infrastructure-less scenarios and is low-cost, quickly deployable and energy-efficient while providing reasonable accuracy for the applications. In this paper, we propose CoCoA, Coordinated Cooperative Ad-Hoc localization. In CoCoA only a subset of the robots in the mobile robot team are equipped with external localization devices (e.g. GPS, or laser rangers with SLAM). Subsequently, while robots perform their tasks, the subset of robots with localization devices help to localize other robots, avoiding the need for static landmarks to be deployed. This is achieved using a modified Bayesian inference-based localization algorithm previously proposed for localization in sensor networks. In addition, CoCoA coordinates this localization process using multicast to put wireless devices in sleep mode periodically which provides significant energy savings. Using detailed simulations and localization models calibrated from experimental data, we find that CoCoA is effective in reducing energy consumption while providing good localization accuracy. [ABSTRACT FROM AUTHOR]

Wireless mesh networks (WMNs) have been proposed as an effective solution for ubiquitous last-mile broadband access. Three key factors that affect the usability of WMNs are high throughput, cost-effectiveness, and ease of deployability. In this paper, we propose DMesh, a WMN architecture that combines spatial separation from directional antennas with frequency separation from orthogonal channels to improve the throughput of WMNs. DMesh achieves this improvement without inhibiting cost-effectiveness and ease of deployability by utilizing practical directional antennas that are widely and cheaply available (e.g., patch and yagi) in contrast to costly and bulky smart beam forming directional antennas. Thus, the key challenge in DMesh is to exploit spatial separation from such practical directional antennas despite their lack of electronic steerability and interference nulling, as well as the presence of significant sidelobes and backlobes. In this paper, we study how such practical directional antennas can improve the throughput of a WMN. Central to our architecture is a distributed, directional channel assignment algorithm for mesh routers that effectively exploits the spatial and frequency separation opportunities in a DMesh network. Simulation results show that DMesh improves the throughput of WMNs by up to 231% and reduces packet delay drastically compared to a multiradio multichannel omni antenna network. A DMesh implementation in our 16-node 802.11b WMN testbed using commercially available practical directional antennas provides transmission control protocol throughput gains ranging from 31% to 57%. [ABSTRACT FROM AUTHOR]