Effects of channel SNR in mobile cognitive radios and coexisting deployment of cognitive wireless sensor networks

In this paper, we describe the cognitive radios sharing the spectrum with licensed users and its effects on operational coexistence with unlicensed users. Due to the unlicensed spectrum band growing needs and usage by many IEEE 802.11 protocols, normal wireless radio operation sees high interference leading to high error rates on operational environments. We study the licensed bands and the characteristics of the unlicensed bands in general and more specific to radio characterization of individual radios and cognitive deployment of sensor networks and its effect on lifetime. The cognitive radio signals detection algorithm for this probabilistic model for the unlicensed users, uses a mobility model which takes into account the threshold variable ratio E_b/N_o and also calculates the lower-bound of the combined value of secondary user interference for overlapping frequencies with the primary user. By using simulation, we detect the primary user when the radio frequencies are known a priori and compare it when the frequencies are unknown. In our analysis we exploit the similarity measure seen at each sub-channel frequency, which are due to multiple paths of the same reflected signal by maximizing the correlated information of the correlation matrix. For the general case the co-variance matrix for blind source separation, we use ICA de-correlation methods and show that cognitive radio can efficiently identify users in complex situations. The effects of large deployment and cognitive sensor network are studied for a family of 802.15.4 radios adapting to power-aware algorithms.