SPECTRUM OCCUPANCY MEASUREMENTS BASED ON ITU-R SM.2256-1 RECOMMENDATIONS IN THE CONTEXT OF COGINITIVE RADIO
The recent popularity of wireless communication, has made the demand for radio spectrum to increase tremendously. Currently, most of the prime radio spectrum bands like the Ultra High Frequency (UHF) TV band are unavailable for any new applications. However, spectrum occupancy measurements done in a number of countries have shown low occupancy in the said bands. It is thus imperative, that if new approaches for accessing the radio spectrum are formulated and adopted, new applications could be accommodated in the existing prime radio spectrum bands. One such approach is the use of the cognitive radio. In Kenya, spectrum occupancy measurements have not exhaustively been done, and hence information on spectrum occupancy, which is a key enabler of cognitive radio, is not readily available.
This paper therefore presents results of spectrum occupancy measurements, carried out in an urban and a rural area in Kenya, in the UHF TV frequency band 470 MHz -694 MHz, in the context of cognitive radio. The spectrum occupancy measurements were carried out, and evaluated in accordance with the ITU-R SM.2256-1 recommendations, to allow results comparison from similar measurements carried out elsewhere. The choice of this band, is due to its good signal propagation characteristics.
An active UHF omnidirectional antenna, in conjunction with a 9 KHz -3.2 GHz spectrum analyzer, were used to collect the spectrum occupancy data over a period of 12 hours, which was then processed in a MATLAB software.
The results obtained from the aforementioned measurement area, showed an average spectrum occupancy of 49.6 % in the urban area and 26.3 % in the rural area. Thus, about 50 % of the spectrum in this band is unutilized in the urban area, and 74 % in the rural area, and hence, could be used for cognitive radio applications, to ease the spectrum scarcity. The results obtained in this study, is in line with similar results presented in the literature.