Statistical Analysis of Modulation Selection Strategies in Cognitive Radios

The new upper bound interference temperature (IT) has provided Cognitive Radios (CRs) with new resources of frequency spectrum. The principle is that CRs are allowed to use channels mainly licensed to some Primary Users (PUs) provided that their operation will not violate the IT limit determined by PUs. In this paper, through statistical analysis, the effect of the modulation selection strategies of active CRs on the probability of blocking new CRs in one hand and on the excessive interference created for PUs on the other will be analyzed. The results, as expected, show that when CRs mostly use higher power modulations, both probability of blocking new CRs and interfering with PUs increase. Also, when CRs use the average power instead of maximum power as their metric for avoiding interfering with PUs, their interference with PUs are more likely, although they possibly obtain higher data rates.