If you're a regular user of a wireless phone, chances are you've experienced the frustration of a "lost" call or a conversation with poor reception. What you might not realize is the connection between your phone's signal and an important area of advanced communications research known as "radio propagation".

Radio propagation research focuses on the interaction between radio waves and the physical media in which they travel (see below for further details). This is the scientific concept behind the functionality of wireless phones, as well as countless other wireless communications technologies. Over the past two decades, the demand for and dependency on such wireless products, services and networks have grown astronomically. According to the Canadian Wireless Telecommunications Association (CWTA), Canadian wireless phone subscribers numbered 19.5 million at September 30, 2007, representing a national wireless penetration rate of more than 60 per cent.

As traffic load in wireless networks increases, there is a need to improve how the radio spectrum is used by these technologies. The Communications Research Centre Canada (CRC) is exploring ways to improve system reliability and techniques to overcome adverse propagation effects.

CRC is a long-time leader in radio propagation research. As it joins Defence Research and Development Canada (DRDC) in celebrating "60 Years of Defence Science in Canada", it is noteworthy to recognize that CRC's beginnings in radio propagation date back to grassroots R&D efforts.

A Snapshot of History

Canada had a modest start in propagation research, made by the National Research Council (NRC) during the 1930s. Wartime requirements for communications resulted in a substantial expansion and acceleration of that work. Commissioned by the Royal Canadian Navy in support of its anti-submarine campaign, an ionospheric sounder was installed in Chelsea, Quebec, in 1941, to study the conditions affecting the transmission of radio waves.

When the war concluded in 1945, the importance of propagation research for peacetime communications was recognized, but its close ties to operational needs made a long-term future within NRC unlikely. A small unit known as the Radio Propagation Laboratory (RPL) continued the work, and was moved to a building on the Prescott Highway just outside of Ottawa in 1947. Following the formation of the Defence Research Board (DRB), the RPL became an integral part of that organization.

The CRC would later evolve from the Defence Research Telecommunications Establishment (DRTE), which existed from 1951-1969 as part of the DRB. In 1969, the federal government established a Department of Communications. The DRTE in its entirety was transferred to the new department's research branch, and renamed the Communications Research Centre Canada.

What is CRC doing today?

With nearly 40 years of experience, CRC has inspired a number of applications for communication systems design and spectrum management and is recognized today as one of the world's leading radio propagation research organizations. CRC's R&D program has been translated into many successful commercial applications, such as the design of cell phone systems and broadcasting networks. Through its technology transfer program, CRC has licensed various elements of its Intellectual Property (IP) to major companies such as CTS International (France), LS Telcom (Germany), and Fox Broadcasting, and to many Canadian SMEs. Among other major users are Industry Canada (for spectrum management and licensing), DND, and the Swiss Federal Office of Telecommunications.

One of the most successful CRC-developed applications is CRC-PREDICT, a unique software package for estimating radio signal strengths on terrestrial paths at VHF and UHF (30 MHz to 3 GHz). CRC-PREDICT accounts for terrain and obstructions (foliage, buildings, etc.) on transmission paths, and is considered to be one of the most accurate prediction models available for these applications. It has been successfully licensed in Canada and worldwide for a number of applications, including land mobile planning, broadcasting and broadcast licensing, point-to-point relays and interference studies.

CRC-PREDICT is an excellent tool for service providers implementing a large-scale application, such as a cell phone company that needs to determine the best location for its base stations. CRC's Broadcast Technology branch has also incorporated the algorithm into several software suites developed mainly for broadcasting applications. Another recent example of CRC-PREDICT in action is an interference assessment conducted by a Montréal-based company. By using CRC-PREDICT as the engine in its in-house models, the company was able to generate detailed estimates of the likelihood of interference to television broadcast services from windmill-energy farms, an issue of concern to Radio-Canada and other service providers.

CRC also has an extensive record of research in Earth-space (satellite) propagation, dating from pioneering work on the fading experienced on paths at very low elevation angles (an early DND concern for Arctic communications with geostationary satellites). One recent project involved evaluation of the severe propagation impairments that occur in tropical climates, due to large storms and heavy rainfall. This study was performed in collaboration with research partners in France, Italy and Brazil, and was funded by the European Space Agency. Perhaps surprisingly, CRC has performed a variety of tropical propagation studies on behalf of several clients, including DND, Industry Canada and CIDA, and has a good reputation in such endeavours. Just as for terrestrial services, mobility is a requirement for many satellite applications. Fisheye photographs (see figure) are used to quantify the probability that a path to the satellite will be available for mobile system users in different environments (urban, rural, etc.).

CRC also plays a government-mandated role in the provision of information required for spectrum management. Some of the R&D results have influenced spectrum policy actions and have been adopted in standards venues on the world stage, such as the International Telecommunication Union (ITU).

As wireless products, services and networks become increasingly interwoven in the social and economic fabric of Canada and around the globe, it is clear that the demand for R&D efforts that advance these developments will only increase with time. With its rich history of radio propagation research, CRC is a uniquely-placed organization that will continue to contribute its capabilities to the Canadian industry, government and research partners the world over.