Towards the development of a wireless network node lifetime calculation tool

The designers, optimizers and maintenance personnel of a wireless sensor network are frequently challenged by system level energy budget considerations. Minimizing the need for battery replacement is often the design goal while ensuring that a balance is maintained between capability and current consumption in order to address application needs. In this paper, a tool is introduced which can be used to calculate the lifetime of a battery operated wireless node. It allows the user to configure different wireless sensor platforms, select a battery of choice, and specify the application which needs to be executed over the configured hardware. As a result, the tool computes an estimate for the expected lifetime of the wireless sensor node. Furthermore, the tool also provides a detailed overview of the energy consumed by each component during a duty cycle. © 2013 IEEE

Technologies to improve the performance of wireless sensor networks in high-traffic applications

The expansion of wireless sensor networks to advanced areas, including structure health monitoring, multimedia surveillance, and health care monitoring applications, has resulted in new and complex problems. Traditional sensor systems are designed and optimised for extremely low traffic loads. However, it has been witnessed that network performance drops rapidly with the higher traffic loads common in advanced applications. In this thesis, we examine the system characteristics and new system requirements of these advanced sensor network applications. Based on this analysis, we propose an improved architecture for wireless sensor systems to increase the network performance while maintaining compatibility with the essential WSN requirements: low power, low cost, and distributed scalability. We propose a modified architecture deriving from the IEEE 802.15.4 standard, which is shown to significantly increase the network performance in applications generating increased data loads. This is achieved by introducing the possibility of independently allocating the sub-carriers in a distributed manner. As a result, the overall efficiency of the channel contention mechanism will be increased to deliver higher throughput with lower energy consumption. Additionally, we develop the concept of increasing the data transmission efficiency by adapting the spreading code length to the wireless environment. Such a modification will not only be able to deliver higher throughput but also maintain a reliable wireless link in the harsh RF environment. Finally, we propose the use of the battery recovery effect to increase the power efficiency of the system under heavy traffic load conditions. These three innovations minimise the contention window period while maximising the capacity of the available channel, which is shown to increase network performance in terms of energy efficiency, throughput and latency. The proposed system is shown to be backwards compatible and able to satisfy both traditional and advanced applications and is particularly suitable for deployment in harsh RF environments. Experiments and analytic techniques have been described and developed to produce performance metrics for all the proposed techniques