Analysis of frequency spectrum usage from a cognitive radio perspective

Inefficient usage of the radio frequency spectrum has been identified as one of the major problems to be solved, in a world where new communication systems appear more often lately than ever before. Cognitive Radio (CR) technology promises to be one possible solution to this problem, by allowing access of unlicensed users in licensed bands, based on an opportunistic approach and without interfering with the licensed (primary) user. A first step in order to identify the frequency bands that are more suitable for opportunistic usage is to evaluate the degree in which licensed bands are currently used. Although some measurement campaigns have already been carried out, most of them were done in the USA and only a few in other locations worldwide. This paper presents results of a measurement campaign conducted in Bucharest, Romania, covering the frequency range from 25 MHz up to 3.4 GHz. The measurement results are confronted with the frequency allocation table published by the national authority for communications and an analysis of the obtained data is being made.