Med-Hoc-Net 2007

Session 2: Services and Applications

Easy Wireless: broadband ad-hoc networking for emergency services 

•  Maurits de Graaf Hans van den Berg, Richard J. Boucherie, Frank Brouwer, Irene de Bruin, Herman Elfrink, Irene Fernandez-Diaz, S. Heemstra de Groot, Roland de Haan, Jan de Jongh, Sindo Nunez, Jan–Kees van Ommeren, Frank Roijers, Jan Stemerdink, Erik Tromp (The Netherlands) 

Abstract: Wireless ad-hoc networks will enable emergency services to continuously overview and act upon the actual status of the situation by retrieving and exchanging detailed up-to-date information between the rescue workers. Deployment of high-bandwidth, robust, self-organising ad-hoc networks will enable quicker response to typical what/where/when questions, than the more vulnerable low-bandwidth communication networks currently in use. This paper addresses a number of results of the Easy Wireless project that enable high bandwidth robust ad-hoc networking. Most of the concepts presented here have been experimentally verified and/or prototyped.

Pages: 32-39

Differentiating Services for Sensor Internetworking

• Lefteris Mamatas (Democritus University of Thrace, Greece)
• Vassilis Tsaoussidis (Democritus University of Thrace, Greece) 

Abstract: We propose NCQ (Non-Congestive Queuing) as a scheduling discipline that allows for efficient interoperation of sensor networks with the Internet. NCQ promotes conditionally small data packets, which require comparatively minor service times, as long as their total service times cause insignificant delays to other packets in the queue. Therefore, NCQ introduces a new service philosophy, which prioritizes packets, and in turn corresponding flows, according to their impact on total delay. In this context, we also introduce a corresponding index to measure fairness as a function of the deviation of expected and received delay. 

Pages: 40-47

TCP Adaptive RTO to improve TCP performance in mobile ad hoc networks

• Haifa Touati (National School of Computer Science, Tunisia)
• Ilhem Lengliz (Prince Sultan University, Saudi Arabia)
• Farouk Kamoun (National School of Computer Science, Tunisia) 

Abstract: In a mobile ad hoc network, temporary link failures and route changes occur frequently. With the assumption that all packet losses are due to congestion, TCP performs poorly in such an environment. This paper proposes a new mechanism called TCP Adaptive RTO (TCP AR) that improves TCP performance in mobile ad hoc network s. TCP AR distinguishes routes failures from network congestion and adapts the RTO’s value to network conditions. For this purpose it relies on the estimation of the network’s throughput. Using the NS-2 simulator we compared TCP AR throughput to th ose of TCP New Reno and TCP Westwood using different scenarios which vary in nodes’ mobility and traffic load. The simulation results discussed in this paper show that TCP AR can achieve up to a 152% improvement in network throughput. 

Pages: 48-55

Multimedia over Wireless Mesh Networks: Results from a Real Testbed Evaluation

• Vincent Chavoutier (Institut Superieur d’Electr. de Paris, France)
• Daniela Maniezzo, (University of California, USA)
• Claudio E. Palazzi, (Universita di Bologna, Italy)
• Mario Gerla (University of California, USA) 

Abstract: Wireless mesh networks are the next step in the evolution of wireless architecture, delivering services for a large variety of applications in personal, local, campus, and metropolitan areas. Unlike WLANs, mesh networks are self-configuring systems where each Access Point (AP) can relay messages on behalf of others, thus increasing the range and the available bandwidth. Key advantages of wireless mesh networks include ease of installation, no cable cost, automatic connection among  nodes, network flexibility, automatic discovery of newly added nodes, redundancy, and self-healing reliability. At UCLA Network Research Lab, we created a testbed for Wireless Mesh Networks using the Mesh Connectivity Layer, part of the Microsoft Mesh Toolkit 2005. In this paper we focus on indoor scenarios, such as home environments and offices. As the demand for rich-media, streaming video content continues to increase, this kind of applications certainly represents a main player in the considered scenarios. Using our testbed, we delineate the limits of multimedia streaming with today’s WMN technology.