Technical Note: Novel method for water vapour monitoring using wireless communication networks measurements

摘要

We propose a new technique that overcomes the obstacles of the existingmethods for monitoring near-surface water vapour, by estimating humidityfrom data collected through existing wireless communication networks.Weather conditions and atmospheric phenomena affect the electromagneticchannel, causing attenuations to the radio signals. Thus, wirelesscommunication networks are in effect built-in environmental monitoringfacilities. The wireless microwave links, used in these networks, are widelydeployed by cellular providers for backhaul communication between basestations, a few tens of meters above ground level. As a result, if allavailable measurements are used, the proposed method can provide moistureobservations with high spatial resolution and potentially high temporalresolution. Further, the implementation cost is minimal, since the data usedare already collected and saved by the cellular operators. In addition –many of these links are installed in areas where access is difficult such asorographic terrain and complex topography. As such, our method enablesmeasurements in places that have been hard to measure in the past, or havenever been measured before. The technique is restricted to weatherconditions which exclude rain, fog or clouds along the propagation path.Strong winds that may cause movement of the link transmitter or receiver (orboth) may also interfere with the ability to conduct accurate measurements.We present results from real-data measurements taken from two microwavelinks used in a backhaul cellular network that show convincing correlationto surface station humidity measurements. The measurements were taken dailyin two sites, one in northern Israel (28 measurements), the other in centralIsrael (29 measurements). The correlation between the microwave linkmeasurements and the humidity gauges were 0.9 and 0.82 for the north andcentral sites, respectively. The Root Mean Square Differences (RMSD) were1.8 g/m3 and 3.4 g/m3 for the northern andcentral site measurements, respectively.