Research Activities

CMOS Cognitive Radio

To avoid interference, radio communication is subject to regulations, which assign dedicated parts of the radio frequency spectrum to dedicated services. Due to this static frequency planning, large parts of the spectrum remain temporarily locally unused. To better exploit the scarce available spectrum, new radio devices could monitor the locally available spectrum, and use unused or "white space", but “step aside” if traditional radio services enter the picture. This requires a smart agile radio transmitter/receiver, aware of its radio environment, referred to as a “Cognitive Radio”.

Cognitive radio requires a very flexible radio, a kind of "software radio" with highly flexible hardware programmable by software. However, state-of-the-art radio functionality is still largely defined in hardware and is highly dedicated for one specific radio standard, optimized for cost and power consumption, but certainly not for flexibility. In this project we aim at a highly flexible cognitive/software-defined radio transmitter in CMOS. An agile radio transmitter is difficult because the transmitter should not cause interference in other frequency bands, while traditional fixed-frequency band-pass filters cannot be used (are not programmable). In recent publications, a new multiphase multipath radio transmitter architecture without any dedicated filters has been proposed, which only causes very low interference. In this project we want to explore the application of this technique to cognitive radio. The key focus points will be the (digital) generation of multi-phase signals, the Digital to Analog conversion and ways to minimize the power dissipation of the architecture.