Center for Embedded Network Sensing

Wireless sensor networks will allow fine-grained monitoring in a wide range of environment (indoor and outdoor). Many of these environments, present very harsh conditions for wireless communication using low-power radios, including multipath/fading effects, reflections from obstacles, and attenuation from foliage. In this work, we introduce scale, a network wireless measurement tool that uses packet delivery as the basic application-level metric. Scale facilitates the gathering of packet delivery statistics using the same hardware platform and in the same environment targeted for deployment. Using up to 55 nodes, we were able to measure and study the connectivity conditions of two hardware platforms, mica 1 and 2 motes, in three different environments: an outdoor habitat reserve, an urban outdoor environment in a university campus, and an office building, under systematically varied conditions. Among other things, we found that there is no clear correlation between packet delivery and distance in an area of more than 50% of the communication range, temporal variations of packet delivery are correlated with mean reception rate of each link, and the percentage of asymmetric links varies from 5% to 30%...