Opportunist radio

1. Introduction

In the early 2000, some measurements have been done by the Shared spectrum company showing that some spectrum bands are over-exploited whereas some bands remains under-used. To equilibrate the use of the spectrum in the classical frequency bands, the concept of opportunist radio has emerged. The idea is that an opportunist system is able to sense the occupancy of the spectrum in its neighborhood, and to establish a communication in the free bands.

The opportunist radio is a concept derived from the concept of Cognitive radio. The cognitive part of an opportunist system is the capability to detect and exploit the free bands. Note that the IEEE international conference DySPAN is dedicated to this issue.

2. Numerical dividend

The first studies have been done about an opportunist usage of the UHF bands because of the numerical dividend. The numerical dividend is the set of frequency bands that will be released with the end of the diffusion of the analog TV. These studies have been legitimated with the FCC note [1] proposing to authorize opportunist radio to works in the UHF bands. In Europe, this kind of usage is still in discussion by the ERO TG4 group.
In the US, the IEEE 802.22 WG is in charge of proposing a standard for broadband communications in the UHF bands.


The main issues of opportunist access to UHF bands are the detection of NTSC signals in the US and DVB signals in Europe, and the detection of PMR systems (such as microphones). The studies objectives are to propose a global spectrum sharing solution based on a cognitive bloc that ensure an interference noise level controlled.

3. Opportunist access to whole spectrum resources

Others initiatives have started to study the opportunist spectrum access to the whole spectrum. The normalization group IEEE P1900 works on this topic. The IST project ORACLE also deals with this issue.

4. External links

• Shared spectrum company
• DySPAN
• ORACLE IST Project
• IST Projects dedicated website

References:

[1] FCC 2003. Facilitating Opportunities for Flexible, Efficient, and Reliable spectrum Use Employing Cognitive Radio Technologies. FCC Document ET Docket No. 03-108, Dec. 2003