An opportunistic cognitive radio communication through the exploitation of the small-scale fading mechanisms of the LTE mobile channel

Abstract

In recent years, the cognitive radio technology has attracted the attention of all the players in the telecommunication field (i.e., researchers, industry, service providers, and regulatory agencies) as a way of facing the spectrum scarcity. In this regard, and after having reviewed the vast activity linked to this concept it is quite easy to realize that the spectrum sensing task turns out to be the keystone of this technology. However, nowadays it is still unclear which is (are) going to be the globally recommended technique(s) for carrying out this procedure. So, and aiming at finding an alternative to the technical impediments behind the spectrum sensing task, this research work proposes that the advanced knowledge that is already being collected at the modern primary networks be used in benefit of the cognitive radios. Here, the 3GPP LTE network has been adopted as the primary system providing the information that the cognitive radio transceiver will be using for co-transmitting opportunistically (i.e., at specific moments) through the licensed radio resources, being the secondary access based on a novel model which proposes to overlay the secondary transmission whenever extreme channel conditions be found in the radio link of a particular primary user.

Channel Measurement and Modeling in Complex Environments

“…Time variance of the channel : since the received multipath components (MPs) are highly dependent not only on the signal frequency but also on the position of the antenna [12], the significant time variation may occur due to: (i) the relative motion between the transmitter and the receiver, which results in the random frequency modulation because of the Doppler shift f d . The Doppler shift can be positive or negative depends on the mobile receiver is moving towards or away from the transmitter; (ii) the movement of surrounding objects in the propagation environment.…”