Implications of link range and (In)stability on sensor network architecture.

In this work, we consider sensor networks used for scientific instrumentation, where we have a set of nodes collecting data and relaying the same to a central base node. From the point of view of deploying such networks,we re-look at the design choices available for the network architecture and protocol design. A design choice which has not received in-depth attention thus far is the use of external antennas for improving the communication range. We present extensive measurements to quantify the use of external antennas. We show that this is a simple yet effective mechanism, in many cases allowing the use of just a single-hop network architecture. Such an approach of course, also greatly simplifies protocol design. Related to the range studies, we also look at the time variability of RSSI and the packet error rate. We find variability at time scales as small as a single packet and also at several hours. Given this, we argue that dynamic metric based routing becomes highly questionable, and a centralized protocol design becomes a serious alternative.