Wave Propagation Analysis at 433MHz ISM Band for Wireless Sensor Networks

Power efficiency and increased range were key considerations in the design of a wireless sensor network. A ‘set and forget’ strategy is desirable, particularly for low data rate applications. Zigbee and Bluetooth are two standards used for wireless connectivity at 2.4 GHz. However, due to higher path loss at these frequencies, the range of Zigbee and Bluetooth transceivers is quite limited. DASH7 protocol enabled devices operating in the 433MHz ISM band are an alternative for low data rate, long range wireless connectivity. This paper presents the link performance analysis of the DASH7 protocol on off-the-shelf Wizzi sensor kits. Experimental characterization of the link quality was carried out in environments such as tunnel-like corridors, between buildings, grass fields and straight roads. Packet Error Rate (PER), Received Signal Strength Indicator (RSSI) and link asymmetry were measured at different power levels for different separation distances between the devices.