RF architecture for wireless sensor network coverage improvement

In this paper, we describe an RF architecture to Improve coverage and performance of a wireless sensor network. We consider IEEE 802.15.4 ZigBee devices to realize a building automation and energy management system. ZigBee operates typically at 2.4 GHz and may suffer of coverage problems in harsh propagation environments as in large buildings. In order to improve performance, we propose the use of lower frequencies. In particular, the 800 MHz and 400 MHz spectrum can be considered still fulfilling European frequency allocation norms. We describe the design of the required RF front-end. An hardware prototype has been realized. We show that it can be used as a plug-in module for existing ZigBee devices operating at 800 MHz that enables the transmission at 400 MHz and 800 MHz in a selective mode.