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JTRS MOVING CLOSER TO VISION OF COGNITIVE RADIO
By Kris Osborn, US Army

04 May 12. The Joint Program Executive Office for Joint Tactical Radio Systems, or JTRS, is moving closer to its vision of Cognitive Radio, a concept engineered to allow a family of software-programmable radios to better use portions of the available spectrum, service officials said.

Cognitive Radio allows JTRS radios to more efficiently draw upon high-bandwidth waveforms, ensure maximum interoperability among deployed forces and preserve the security of combat-relevant voice, data, images and video transmitted across the force in real time.

A principle advantage of the JTRS family of radios, which have progressed substantially over more than a decade of technological development, is that they create and sustain secure, mobile, ad-hoc “terrestrial” and “aerial-tier” networks able to safely transmit vital, combat-relevant information across large distances. JTRS radios are engineered to accomplish this by being able to move information across deployed forces potentially located in austere, forward-positioned environments without needing a “fixed” infrastructure such as cell towers or satellite networks.

Each radio functions as a “node” or “router” on the network, extending its reach and mobility across a range of potentially uneven terrain and tactical, combat environments. Security methods such as anti-jam capability and encryption of IP or internet protocol packets of information sent wirelessly through high-bandwidth waveforms such as Soldier Radio Waveform and Wideband Networking Waveforms are a fundamental element of this equation and a huge priority in the development of JTRS radios.

“With more radios vying for increasing scarce spectrum space, there’s a growing need for cognitive radios that use computer intelligence to automatically and invisibly adapt themselves to user needs and band conditions. Cognitive radio is an umbrella term for an array of different technologies that allow radios to achieve various levels of self-configuration, including automatic operating mode selection, optimal power output and dynamic spectrum access for interference management,” said Brig. Gen. Michael Williamson, joint program executive officer, JTRS.

Cognitive Radio helps bring this to fruition by facilitating what JTRS engineers call Dynamic Spectrum Access, or DSA, described essentially as the ability of the radio to locate and use the available spectrum by automatically changing its transmission or reception parameters, Williamson explained.

“DSA allows a JTRS device to sense the available spectrum, discover unused frequencies and adapt to the radio frequency environment, maintaining reliable communications with other DSA-enabled JTRS devices,” he said.

In this respect, the concept of Cognitive Radio envisions a “self-healing,” and “self-adapting” two-way radio able to more efficiently and effectively use limited spectrum while ensuring interoperability and security, he added.

“Cognitive attributes of spectrum ‘sharing’ and ‘agility’ are key to the future. Cognitive Radios are capable of dynamic spectrum utilization that takes advantage of unused channel occupancy or so-called ‘White spaces’. The challenge is to be able to utilize these channels when they are not occupied and to exit the channel without harm to the channelowner when he turns on. Spectrum sensing is a critical function for future radio systems and JTRS is the platform to deliver capability to the warfighter,” Williamson said.

Both SRW and WNW are high-bandwidth waveforms because they draw upon a larger portion of the available spectrum to more quickly and efficiently transmit information when compared with legacy waveforms; SRW is designed to efficiently use spectrum in 1.2-Megahertz bandwidth allotments. WNW can also support 1.2-Megahertz allotments, but it operates more efficiently and effectively at 3 or 5-Megahertz bandwidth allotments (up to 30 Megahertz

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