Empirical evaluation of OI-MAC: Direct interconnection between wireless sensor networks for collaborative monitoring

Cooperation between co-located Wireless Sensor Networks (WSNs) has the potential to present new opportunities for novel applications and provide network performance improvements. The traditional interconnection approach for WSNs is based on a backbone network such as the Internet, but this may have intermittent or unavailable connectivity in remote locations. To address this, Opportunistic Direct Interconnection (ODI) has been proposed to allow distinct and independent WSNs to communicate directly with neighbouring networks, and OI-MAC is a link-layer protocol which implements this functionality. However, OI-MAC has not been experimentally validated, instead with analysis performed through simulation. In this paper, we present a practical implementation of OI-MAC using two separate multi-hop networks with 6 sensor nodes in each. We validate its effective operation through experimentally obtained timing diagrams, sensor data output, and energy consumption. Results show successful cross-network packet communication, while networks remain independent by maintaining individual configurations and communication channels. Furthermore, we show that the process of discovering neighbouring networks has an insignificant impact on energy consumption.