Cognitive radios are able to dynamically allocate and exploit spectral resources to optimize wireless communication networks' capacity and/or the quality of service (QoS). Although this dynamic spectrum management is not allowed in France yet, this paradigm is seen by many stakeholders as an efficient means to de-saturate the crowded radio spectrum.
In the U.S., unlicensed opportunistic spectrum usage has been authorized in the free channels of the television spectrum (the Television White Space – TVWS) by the Federal Communications Commission (FCC). The service envisioned by the FCC is a long-range WIFI system, called super-WIFI.
Ongoing studies have been evaluating whether a similar paradigm could be applied in Europe, for instance in the framework of the SE43 group of the European Conference of Postal and Telecommunications Administrations (CEPT). The technology developed by Leti can be applied in both Europe and the U.S.
The STCS department’s cognitive radio research focuses on two fundamental issues related to dynamic spectrum access (DSA). These are free-channel detection and flexible high-spectrum-efficiency communication systems with a low power leakage in the adjacent channels, known as adjacent channel leakage ratio (ACLR). Many applications are envisioned because the radio propagation at TVWS frequencies (470 to 780MHz) – the so-called “golden frequencies” – is excellent for outdoor or outdoor/indoor applications.
This is a key asset in comparison to typical WIFI frequencies (2.4 or 5.4GHz) that opens the way to new application opportunities: home networking, campus networks, intelligent cities, public safety, etc. Leti’s TVWS experiments will validate the low ACLR radio for urban and indoor-to-outdoor scenarios, in order to quantify the improvements in terms of system capacity and coexistence with incumbent radio systems.
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