A research team at the Communications Research Centre Canada (CRC), in partnership with Defence Research and Development Canada (DRDC), is working to develop an improved tactical radio communications system to meet current and future military requirements.

Known as the High Capacity Tactical Communications Network (HCTCN), this experimental system aims to provide several key improvements while optimizing the flow of data and voice information within bandwidth-constrained wireless networks.

"The Canadian military is always striving to exploit new technologies to meet the challenges of modern day operations," explained Joe Schlesak, the research manager leading the development of the HCTCN system. "The ability to effectively exchange information between the various mobile units is a critical issue for any tactical military operation. The increasing demand for data transmission to support situational awareness is rapidly exceeding the capabilities of the currently deployed low-bandwidth wireless networks, which use relatively low bit rate waveforms for transmission."

At the heart of CRC's experimental system is the development of a high data rate Very High Frequency (VHF) waveform, using advanced signal processing techniques. The higher data rates have allowed the introduction of network-centric capabilities, and the efficient integration of voice and data within bandwidth-constrained tactical communications systems.

By using a high data rate modem (64 kbps), the HCTCN demonstrator has introduced several new capabilities to the tactical network. In voice communication, in addition to the existing all-informed capability, the use of the Internet Protocol allowed for the possibility of selecting the called party(ies): point-to-point, point-to-multipoint, and conferencing capabilities were demonstrated. In addition, the new system allows for call pre-emption, where a higher ranking officer can interrupt an ongoing point-to-point call.

The HCTCN also aims to address the critical issue of reliability, for use in a military context. In consumer WiFi networks known as "hotspots," like those found in Internet cafés and airports, all nodes link into a base station. The reliability of such a system is inadequate for military use, since if the base station stops functioning the entire network goes down.

The HCTCN provides greatly improved reliability through the use of a mobile ad-hoc networking (MANET) topology, where each radio becomes like a router, directing information packets to where they need to go. This means that it functions without being linked to a base station, thereby allowing for direct communication between two radios, and relaying. The latter capability is critical in the case where two radios are unable to communicate directly, due to distance, an obstacle between two nodes, and other factors. The ad-hoc nature of the network allows for survivability; if a commander radio becomes unusable, a second-in-command radio automatically takes over.

The HCTCN experimental system developed by CRC researchers has identified some practical challenges in the networking of low-bandwidth radio networks. These challenges have created opportunities for designing new, optimized network protocols for bandwidth-restricted, error-prone radio networks. Ongoing work is being conducted with international collaboration to address these challenges.

In addition to its tangible experimental system, CRC is also working to influence the development of a NATO standard for high-data-rate VHF radio communications. Through its partnerships, CRC plans to license and transfer the technology to Canadian industry.

For more information about CRC's military wireless R&D, please visit: http://crc.ca/en/html/crc/home/research/wireless/mil_wireless