Policy Defined Spectrum sharing and medium Access for Cognitive Radios

Abstract

Spectrum regulation will undergo elementary changes in the near future allowing a less restricted and more flexible access to radio spectrum. Intelligent radios, so- called 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.