Metrics are investigated to help assess the performance of wireless sensors in buildings. Wireless sensor networks present tremendous opportunities for energy savings and improvement in occupant comfort in buildings by making data about conditions and equipment more readily available. A key barrier to their adoption, however, is the uncertainty among users regarding the reliability of the wireless links through building construction. Tests were carried out that examined three metrics as a function of transmitter-receiver separation distance, transmitter power level, and obstruction type. These tests demonstrated a clear transition from reliable to unreliable communications at different distances. The packet delivery rate showed this transition. While this value is difficult to measure in actual applications, the received signal strength indication correlated well with the drop in packet delivery rate in the relatively noise-free environment used in these tests. The concept of an equivalent distance was introduced to translate the range of reliability in open field operation to that seen in a typical building, thereby providing wireless system designers a rough estimate of the necessary spacing between sensor nodes in building applications. It is anticipated that the availability of clear metrics on the range of wireless sensors in buildings will enable more widespread sensing in buildings for improved control and fault detection.
Citation: Building and Environment
Pub Type: Journals
wireless, sensor networks, building monitoring, reliability, metrics