More and more, users demand that wireless technologies provide high availability, ubiquitous communications over large areas. This becomes increasingly difficult as the distance between end users grows, as is the case for many military operations. They require reliable, strategic and tactical long-range communications even in the most challenging environments where difficult terrain is the norm.  

Delivering this wireless capability can be very challenging. To help overcome the challenges, the Wireless Applications and Systems Research group (WASR) of the Communications Research Centre (CRC) has been working with the Director Land Command Systems Program Management 3 (DLCSPM 3) of the Department of National Defence (DND) on the use of aerostats to enhance wireless communications. Essentially, an aerostat is a lighter-than-air object that can be raised significantly above ground while remaining in a relatively fixed position. It can then be used to greatly improve the line-of-sight coverage of a base station radio to a number of end users located at ground level.

"The Canadian Military continuously searches for new technologies that can lead to innovative approaches for modern day operations. In the area of wireless communications, the aerostat is one of these technologies that is showing promise," explains Cy Aiken, Senior Systems Engineer of DLCSPM.

Researchers conducted the first phase of this study at Canadian Forces Base Suffield, Alberta in December 2008, where DND launched an aerostat for the first time. They chose a rapidly deployable 17-meter long tethered balloon. Researchers raised the aerostat to 180 meters above ground level while it carried a variety of wireless technologies in a payload container suspended beneath the balloon.

WASR evaluated one of these technologies, an 802.16-based broadband wireless fixed WiMAX system. CRC researchers integrated a WiMAX base station and omni-directional antenna into the aerostat payload. Once the aerostat was raised, they conducted a series of tests at ground level using up to 10 subscriber units that communicated with one another via the base station on the aerostat. Researchers were particularly interested in the increased range among subscriber units as a result of the elevated base station on the aerostat, the increased throughput amongst users as a result of improved line-of-sight conditions, and improved coverage ubiquity.

The preliminary results of this work indicate that aerostats may indeed be a viable technology to improve wireless communications for military operations. WASR will continue to work with DLCSPM in this promising area.

For more information contact Joe Fournier, Senior Research Engineer, Wireless Applications and Systems Research, at 613-949-0175 or joe.fournier@crc.gc.ca.

This diagram highlights the improved coverage resulting from the aerostat. The yellow area indicates the predicted coverage of a base station located approximately 30 meters above ground level using a sophisticated RF planning tool. The green area illustrates the coverage improvement achieved by raising the base station to 180 meters above ground level using an aerostat. The improvement is significant, with up to 50 kilometers more range in some directions.