The bus goes wireless: Routing-free data collection with QoS guarantees in sensor networks

Abstract

Abstract-We present the low-power wireless bus (LWB), a new communication paradigm for QoS-aware data collection in lowpower sensor networks. The LWB maps all communication onto network floods by using Glossy, an efficient flooding architecture for wireless sensor networks. Therefore, unlike current solutions, the LWB requires no information of the network topology, and inherently supports networks with mobile nodes and multiple data sinks. A LWB prototype implemented in Contiki guarantees bounded end-to-end communication delay and duplicate-free, inorder packet delivery-key QoS requirements in many control and mission-critical applications. Experiments on two testbeds demonstrate that the LWB prototype outperforms state-of-theart data collection and link layer protocols, in terms of reliability and energy efficiency. For instance, we measure an average radio duty cycle of 1.69 % and an overall data yield of 99.97 % in a typical data collection scenario with 85 sensor nodes on Twist. I. INTRODUCTIONProviding and analyzing Quality of Service (QoS) guarantees are key factors in making low-power wireless networks viable for a variety of applications, including safety-critical alarm systems, real-time control for factory automation, and mission-critical patient monitoring. These applications rely on a data collection service that provides bounded end-to-end delays, highly reliable packet delivery, and energy efficiency to achieve system lifetimes of several years. However, current solutions often fall short of these requirements, especially in multi-hop networks involving mobile nodes and multiple sinks.A major obstacle in current solutions is their strong dependency on the network topology. To cope with the multi-hop nature of low-power wireless networks, they let nodes continuously collect information about link qualities and neighboring nodes, serving, for example, as input to routing and TDMA scheduling algorithms [11], [15]. Keeping such network state up-to-date in a wireless environment, where channel conditions change frequently [27], consumes significant bandwidth and energy. Node mobility compounds the problem as network state becomes quickly outdated [9]. Moreover, many existing solutions use multiple protocols concurrently, which can lead to unintended interactions that impair system performance and cause failures difficult to find and fix [8], [25], or they employ cross-layer designs, which often increase complexity and thus hamper analysis of the provided QoS guarantees [26].To tackle the issues above, we adopt a clean-slate design and rethink the entire networking stack. In particular, we propose the low-power wireless bus (LWB), a novel communication paradigm for data collection with QoS guarantees.