The Mars sensor network: efficient, energy aware communications

Data centric sensor networks will play an important role in planetary explorations. In the future JPL envisions sending in-situ missions with distributed instruments and sensors capable to cooperate autonomously and to collect scientific measurements (gases, chemicals, temperature, etc.). A lander or a rover functioning as a base station collects measurements and relays aggregated results to an orbiter. The wireless, multi-hop communication network connecting instruments (sensors) and the rover is functionally similar to the packet radio networks used in other ad hoc networking environments (e.g., automated battlefield, civilian emergencies, group networking, etc.). Thus, it can exploit some of the protocols developed for the latter. This paper proposes a poll-reply scheme in collecting the sensor data. Investigations of this model show an uneven distribution of energy consumption among nodes especially those close to base station. As the energy conservation and the network lifetime are critical issues for these small energy constrained sensor nodes, our paper further presents a clustering assisted, energy aware polling model. Using the passive clustering protocol, the approach provides an efficient forwarding mesh and results in more evenly distributed energy consumption without introducing extra control messages to the network. The network lifetime is prolonged while maintaining connectivity and satisfying latency constraints.