Guillaume Chelius

Strategies for data dissemination to mobile sinks in wireless sensor networks

A wireless sensor network is a multihop wireless network consisting of spatially distributed autonomous sensors with sensing, computation, and wireless communication capabilities. Generally, each sensor has the task to monitor and measure ambient conditions and disseminate the collected data toward a base station, or sink, for data post-analysis and processing. Many data dissemination protocols have been proposed to allow the dissemination of the collected data toward a static sink. Recently, mobile sinks were shown to be more energy-effective than static ones. In this article, existing data dissemination protocols supporting mobile sinks are summarized. In addition, sink mobility is analyzed, as well as its impact on energy consumption and the network lifetime.

Bandwidth Estimation for IEEE 802.11-Based Ad Hoc Networks

Since 2005, IEEE 802.11-based networks have been able to provide a certain level of quality of service (QoS) by the means of service differentiation, due to the IEEE 802.11e amendment. However, no mechanism or method has been standardized to accurately evaluate the amount of resources remaining on a given channel. Such an evaluation would, however, be a good asset for bandwidth-constrained applications. In multihop ad hoc networks, such evaluation becomes even more difficult. Consequently, despite the various contributions around this research topic, the estimation of the available bandwidth still represents one of the main issues in this field. In this paper, we propose an improved mechanism to estimate the available bandwidth in IEEE 802.11-based ad hoc networks. Through simulations, we compare the accuracy of the estimation we propose to the estimation performed by other state-of-the-art CoS protocols, BRulT, AAC, and CoS-AODV.

Worldsens: development and prototyping tools for application specific wireless sensors networks

In this paper we present Worldsens, an integrated environment for development and rapid prototyping of wireless sensor network applications. Our environment relies on software simulation to help the designer during the whole development process. The refinement is done starting from the high level design choices down to the target code implementation, debug and performance analysis. In the early stages of the design, high level parameters, like for example the node sleep and activity periods, can be tuned using WS- Net, an event driven wireless network simulator. WSNet uses models for applications, protocols and radio medium communication with a parameterized accuracy. The second step of the sensor network application design takes place after the hardware implementation choices. This second step relies on the WSim cycle accurate hardware platform simulator. WSim is used to debug the application using the real target binary code. Precise performance evaluation, including real-time analysis at the interrupt level, are made possible at this low simulation level. WSim can be connected to WSNet, in place of the application and protocol models used during the high level simulation to achieve a full distributed application simulation. WSNet and WSNet+WSim allow a continuous refinement from high level estimations down to low level real-time validation. We illustrate the complete application design process using a real life demonstrator that implements a hello protocol for dynamic neighborhood discovery in a wireless sensor network environment.

Scalable versus Accurate Physical Layer Modeling in Wireless Network Simulations

In wireless networking, due to the high complexity of analytical and theoretical models, simulations are generally considered as the most convenient methodology for performance evaluation. Nonetheless, the physical complexity of the wireless medium induces a clear tradeoff between accuracy and scalability in a wireless network simulator design. In this paper, we focus on this tradeoff and study the impact of physical layer (PHY) modeling accuracy in the computational cost of simulations. We first discuss the main aspects of the wireless medium and briefly show how they have been handled in existing simulators. Then, we introduce a flexible and modular PHY simulation framework to analyze in more details their influence on the scalability of simulations.

Improving Accuracy in Available Bandwidth Estimation for IEEE 802.11-based Ad Hoc Networks

In this article, we propose a method to enhance accuracy of the available bandwidth estimation in IEEE 802.11-based ad hoc networks. This method combines medium state monitoring, probability of collision estimation and backoff time evaluation, improving the method described in C. Sarr et al., (2005). We evaluate our solution by simulation on different scenarios and compare it with different QoS routing protocols based on different available bandwidth estimation techniques

Worldsens: a fast and accurate development framework for sensor network applications

In this article, we present Worldsens, a fast and accurate development framework for sensor network applications. World-sens offers an integrated platform for the design, development, performance evaluation and profiling of applications. It relies on two simulators, WSNet and WSim, which are used throughout the application design and implementation, from the high level design choices to the implementation validation. WSNet is a modular event-driven wireless network simulator while WSim is a full platform hardware simulator which takes the target binary code as input and uses instruction cycles as time reference. WSNet and WSim can be used in conjunction to offer a distributed simulation of sensor networks with instruction and radio byte accuracy.

Analytical evaluation of virtual infrastructures for data dissemination in wireless sensor networks with mobile sink

In this paper, we address the problem of data dissemination in wireless sensor networks (WSN) with mobile sink(s). In such a context, the difficulty is for sensor nodes to efficiently track the sink and report the requested data to the sink location. As flat architectures and flooding-based protocols do not scale, overlaying a virtual infrastructure over the physical network has often been investigated as an interesting strategy for an efficient data dissemination in wireless sensor networks. This virtual infrastructure acts as a rendez-vous area for queries and data reports. The main contribution of this paper is to make an analytical comparative study of a variety of virtual infrastructure topologies. The communication cost and the path stretch are evaluated both in the worst and average cases. Finally, existing data dissemination protocols are compared on different applications scenarios.

Worldsens: from lab to sensor network application development and deployment

We present Worldsens, a prototyping and development framework for wireless sensor protocols and applications. Our environment relies on two simulators, WSim and WSNet, and proposes a full simulation and performance estimation of embedded platforms with instruction and radio byte accuracy. During this demo, we propose to demonstrate the interest of the two simulators in stand-alone and in cooperative use.

No Administration Protocol (NAP) for IPv6 router auto-configuration

This paper outlines the concept of auto-organisation in IPv6 networks. If the auto-configuration of hosts is defined by IPv6 and mandatory, these mechanisms can not be assimilated to a fully plug and play feature, as IPv6 routers still have to be manually configured. To succeed in new domains such as SOHO, a full auto-configuration feature must be offered. Indeed, the configuration of 64 bits IPv6 prefixes and the numbering of links is not really friendly and is error prone, especially in home networking. This paper tackles the issues that arise, reviews actual solutions, and proposes a totally distributed protocol named NAP for IPv6 routers auto-configuration.

Mitigating Reply Implosions in Query-Based Service Discovery Protocols for Mobile Wireless Ad Hoc Networks

Providing service discovery in an efficient and scalable way in ad hoc networks is a challenging problem, in particular for multihop scenarios, due to the large number of potential participant nodes and the scarce resources in these networks. In this paper, we propose and evaluate an approach to mitigate the reply implosion problem in query-based service discovery protocols for multihop mobile ad hoc networks. Our simulation results show the scalability and efficiency of the proposed solution. We demonstrate that the proposed scheme considerably reduces the number of transmissions without compromising the efficiency of the service discovery in scenarios of pedestrian mobility.