Delay-Tolerant, Low-Power Protocols for Large Security-Critical Wireless Sensor Networks

This paper reports the analysis, implementation, and experimental testing of a delay-tolerant and energy-aware protocol for a wireless sensor node, oriented to security applications. The solution proposed takes advantages from different domains considering as a guideline the low power consumption and facing the problems of seamless and lossy connectivity offered by the wireless medium along with very limited resources offered by a wireless network node. The paper is organized as follows: first we give an overview on delay-tolerant wireless sensor networking (DTN); then we perform a simulation-based comparative analysis of state-of-the-art DTN approaches and illustrate the improvement offered by the proposed protocol; finally we present experimental data gathered from the implementation of the proposed protocol on a proprietary hardware node. 1. Introduction In recent years, wireless sensor networks (WSN) research has grown exponentially spreading through several fields of science, from circuit design to algorithm design, antenna design, and protocol design. The main constraints that a generic WSN node has to deal with can be summarized by its limited computing resources and its energy consumption requirements. While the computing resources and corresponding consumed energy tend to grow with silicon technology improvements, available energy budget does not advance very fast with battery technology or can even be bounded in other cases (i.e., energy scavenged from the environment). Power management must therefore be taken into account at every level of the design of any WSN. In security-critical applications, the deployment of large networks faces—among others—the implications of delay variability on the correct operation of security algorithms. This paper illustrates the results of an industrial work on the analysis, optimization, implementation, and experimental testing of a dedicated protocol featuring delay tolerance and energy efficiency for large WSNs in the security application domain. This paper is organized as follows: in Section 2 we present an overview on wireless sensor networking with particular regard to delay-tolerant networking (DTN) and specifically to the DTN logical link control (LLC) layer, with the aim of stating general and direct hints for the protocol design. Section 3 illustrates a dedicated DTN simulation framework and presents simulation results on existing widely used protocols compared with the newly proposed protocol. Section 4 presents the test methodology and the experimental results on a working application of the new