The medium access control being the main source of energy wastage in wireless sensor networks, energy-efficiency is always kept in mind while designing the communication stack. Especially, versatile preamble-sampling MAC protocols emerged to offer a suitable solution over multiple deployment characteristics. For instance, some works have targeted burst transmissions while others have focused on long-term energy-efficiency for mostly sleeping wireless sensors. In this paper, we observe to what extent versatility applies to dynamic scenarios in which communications do not respect specific paradigms. We show that preamble-sampling protocols lack an optimal configuration for antagonist traffic patterns. We therefore introduce an auto-adaptive algorithm that can adjust its sampling period and preamble length. Our solution is based on a link-by-link negotiation in order to establish energy-efficient communications over certain paths toward the sink station. This mechanism, auto-adapting to the current network traffic, can be used in combination with various preamble-sampling MAC layers, and works for every traffic pattern, being especially energy-efficient during burst transmissions. We particularly studied its association with X-MAC, and observed that energy savings are not accomplished to the cost of reliability.

Abstract In the past few years, the concept of pervasive connectivity has become of crucial importance. New protocols have therefore been standardized to enable IPv6 mobility, such as the Network Mobility Basic Support (NEMO BS) protocol. This protocol is particularly suited for providing a global IPv6 connectivity in intelligent transportation systems. Yet, despite its popularity and maturity, it still suffers from various limitations which prevent its adoption in large‐scale commercial deployments. Among these are operator specific issues such as the lack of practical and efficient bootstrapping procedure. Also, a global connectivity enables the provision of value‐added services whose attractiveness mainly depends on their ease of configuration. In this paper, we focus on solutions to address both the bootstrapping of NEMO BS and service discovery in a mobile environment. By investigating various bootstrapping proposals, we advocate the use of a standardized solution extended with the missing pieces to operate in a NEMO BS environment. We also expose how operator services could be exported and announced in the mobile subnet. Authentication and authorization to access these services are also investigated. Experiments on a prototype show that our proposal brings the missing blocks towards the deployment of network mobility service in intelligent transportation systems. Copyright © 2009 John Wiley & Sons, Ltd.

In this paper, we briefly describe an interactive roulette game enabled over a wireless sensor network platform. It basically consists in a train speeding in one way (the spinning roulette) and in a message hopping along some deployed sensors in the other way (the wheeling ball). This demonstration aims at illustrating in an interactive manner the high radio channel randomness in dense wireless sensor networks, as well as its impact on the communication protocols.

Wireless sensor networks operate in constrained environments. In addition to the limitations in terms of energy, memory and computation, the use of mobile sensors has recently been contemplated. However, only a few medium access control protocols consider the dynamic of such scenarios. In this paper, we present potential problems that could arise with nowadays protocols operating in mobile environments. We particularly focus on the synchronization issues between fixed and mobile sensors, as well as congestion in dense networks. For that purpose, we introduce Machiavel, a new method to access the medium. Machiavel allows mobile sensors to capture the channel even in networks with high contention, while guaranteeing the synchronization with their peers. An evaluation by simulation demonstrates the benefits of our contribution compared to the B-MAC protocol.

The Network Mobility Basic Support (NEMO BS) protocol is the IETF standard to manage the mobility of entire IPv6 networks. One of the typical applications of this protocol is to deploy NEMO BS in transportations such as train or bus. As a result, passengers can benefit from global and permanent IPv6 connectivity with legacy IPv6 terminals equipped with a common wireless technology such as Wi-Fi. However, a mobile network is generally managed by a single mobile router which carries out all operations related to mobility and packet forwarding. In this article, we present a new proposal which enables the cooperation of multiple mobile routers to improve the bandwidth, network coverage and reliability of a mobile network. In addition, a dynamic load sharing mechanism between all available mobile routers is supported. This solution mainly relies on Neighbor Discovery and has been experimented on a real testbed.