ISSN : 1796-2021
Volume : 1    Issue : 1    Date : April 2006

Policy Defined Spectrum sharing and medium Access for Cognitive Radios
Lars Berlemann, Stefan Mangold, Guido R. Hiertz and Bernhard H. Walke
Page(s): 1-12
Full Text:
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Spectrum regulation will undergo elementary changes in the near future allowing a less restricted
and more flexible access to radio spectrum. Intelligent radios, socalled cognitive radios, will realize
the dynamic usage of frequency bands on an opportunistic basis, by identifying and using
under-utilized spectrum. Such a flexible spectrum usage requires changes in regulation towards a
more open spectrum. Policies which determine when spectrum is considered as opportunity and
which define the possibilities of using these spectrum opportunities are needed. First, this article
discusses an approach that intends to enable distributed QoS support in open spectrum. This
algorithm is specified as policy in a machine-understandable policy description language, such that
the cognitive radio is capable of reasoning about spectrum usage. Policies that enable a software
defined medium access are the second focus of this article. We discuss a step towards the
realization of such cognitive radios at the example of the well-known Enhanced Distributed Channel
Access of IEEE 802.11e. This channel access protocol is here specified in a machine
understandable policy language, instead of lengthy textual description. Such a machine-
understandable description of the protocol enables cognitive radios to operate in distributed
environments according to the 802.11(e) standard.

Index Terms
Cognitive Radio Networks, EDCA, IEEE 802.11e, Policy Description Language, Spectrum Navigation