Find the weakest link: statistical analysis on wireless sensor network link-quality metrics

Routing protocol plays an important role in data communication. A wireless sensor network (WSN) is usually deployed in scenarios where efficient and energy-aware routing protocols are desired. In wireless sensors, the radio-frequency (RF) modules consume most of the energy. Routing metrics are important in determining paths and maintaining the quality of service in routing protocols. The most efficient metrics need to send packets to maintain link-quality measurement using the RF module. In this article, two prominent link-quality metrics-received signal strength indication (RSSI) and link-quality indication (LQI)-are introduced; the symmetry of RSSI and LQI in two directions has been studied, and relations between the expected transmission count (ETX), RSSI, and LQI as link-quality metrics have been analyzed. The evaluation in this article is based on a series of WSN test beds in real scenarios. The collected data from the test beds show symmetry in the RSSI in both directions as well as a significant correlation between the RSSI and distance, making RSSI a suitable link-quality metric for use in routing protocols for devices that work in limited-resources scenarios.