A Quantitative Analysis of Spectral Occupancy Measurements for Cognitive Radio

Abstract

Cognitive radio (CR) is viewed as a possible solution to the problem of radio spectrum congestion. The CR technique utilizes a temporarily unoccupied licensed band. Before investigating the technical and political implications of CR, it is necessary to know to what extent the licensed bands are temporally unoccupied. This paper describes a spectral occupancy measurement campaign conducted in the frequency range between 806 MHz and 2750 MHz in urban Auckland, New Zealand. The purpose of the measurement is to identify potential spectral opportunities for CR.Statistical analysis of the measurement results are presented in the form of noise distributions, signal amplitude probability distributions, and spectral occupancy rates as percentages of time. These analyses indicate that, on average, the actual spectral usage in this band is only about 6.2%. Point-to-point links and some mobile uplink channels are identified as the most probable candidates for future CR operations. These results suggest that CR could bring significant gains in spectral usage. These results also imply that, in order to provide a reliable detection of the primary signal, cooperative sensing techniques may be necessary to mitigate various wireless channel effects.

Space-dimension models of spectrum usage for cognitive radio networks

“…Note that the models of Sections IV-B1 and IV-B2 are particular cases of the model of Section IV-B3, with (11) reducing to (9) for K = 1 and α < 1, and (7) for K = 1 and α = 1. Thus, the validation of the general form of (11) also validates the particular cases of (7) and (9). Fig.…”

“…Measurements were performed over a set of strategically selected locations in a urban environment (see Fig. 2), including an outdoor high point in a building rooftop with direct line-of-sight to several transmitters a few tens or hundreds of meters apart (location 1), indoor environments (location 2), and additional outdoor locations in narrow streets (locations 3-7), between buildings (locations [8][9][10] and open areas (locations [11][12]. For more details, the reader is referred to [45].…”

Spectrum occupancy investigation: Measurements in South Africa

“…A comparison is made against the reported average occupancy of bands used for television broadcasting as well as those used for mobile cellular communications in Chicago, Vienna (Virginia) and Dublin (Ireland) [5,10,6]. The values presented in Table 3 Certain observations can be made from Table 3 It must be noted that regulatory policy surrounding frequency planning differs amongst these locations.…”

Fundamental limits on time delay estimation in dispersed spectrum cognitive radio systems

“…The studies in [7] and [14] are based on the fact that the available bandwidth is in the form of a single piece (i.e., the whole bandwidth). Since the available bandwidths in dynamic spectrum access systems are commonly dispersed [15], a single cognitive radio user can transmit and receive over multiple dispersed bands. Such systems are referred to as dispersed spectrum utilization systems and are developed in the context of time delay estimation in this study.…”