Dynamic Spectrum Access
by Stefan Mangold, Swisscom Innovations, Berne, Switzerland 

Abstract:

Radio spectrum is today not efficiently utilized because of complicated radio
regulation processes. Access to radio spectrum is frustratingly difficult. The
access is restricted by an old radio regulatory regime that emerged over the
last 100 years. Large parts of our radio spectrum are allocated to licensed
radio services. As a result, open access to most of the radio spectrum is only
allowed with very low transmission powers, in a so-called underlay approach,
as for example used by Ultra Wideband. The overlay approach, i.e., the free
access to open spectrum, is generally not permitted.

Only some small fractions of the radio spectrum, the unlicensed bands, are
openly available, under certain limitations.  The relatively new research
direction carved as Dynamic Spectrum Access is an attempt to change this. With
dynamic spectrum access, so-called cognitive radios coordinate the usage of
radio spectrum without involvement of restrictive radio regulation. They
operate in spectrum when it is not used by licensed radio systems, and
therefore share spectrum with radio systems that have priority access. This is
referred to as vertical sharing. Unused radio spectrum is called a spectrum
opportunity.

In the vertical sharing scenario, cognitive radios adapt their transmission
schemes such that they fit into the identified spectrum usage patterns of the
incumbent radio systems. Note that cognitive radio refers not only to the
radio technology: It also requires a revolutionary change in how our spectrum
will be regulated.

We briefly summarize the major aspects and motivation of dynamic spectrum
access.

Biography:
---------
Stefan Mangold is Focus Topic Leader and Head of Center of Competence Lowest
Cost Networks at Swisscom Innovations, Berne, Switzerland. Before joining
Swisscom in April 2005, Stefan worked with Philips Research U.S.A., and
ComNets RWTH Aachen University, Germany. Stefan received his Masters and his
Dr.-Ing. degree in Electrical Engineering/Telecommunications in 1997 and 2003,
respectively, both from RWTH Aachen University, Germany.