On the Statistics of Cognitive Radio Capacity in Shadowing and Fast Fading Environments (Journal Version)

In this paper we consider the capacity of the cognitive radio channel in different fading environments under a low interference regime. First we derive the probability that the low interference regime holds under shadow fading as well as Rayleigh and Rician fast fading conditions. We demonstrate that this is the dominant case, especially in practical cognitive radio deployment scenarios. The capacity of the cognitive radio channel depends critically on a power loss parameter, $\alpha$, which governs how much transmit power the cognitive radio dedicates to relaying the primary message. We derive a simple, accurate approximation to $\alpha$ in Rayleigh and Rician fading environments which gives considerable insight into system capacity. We also investigate the effects of system parameters and propagation environment on $\alpha$ and the cognitive radio capacity. In all cases, the use of the approximation is shown to be extremely accurate.Comment: Submitted to the IEEE Transactions on Wireless Commun. The conference version of this paper appears in Proc. IEEE CrownCom, 200

On the Statistics of Cognitive Radio Capacity in Shadowing and Fast Fading Environments

In this paper we consider the capacity of the cognitive radio (CR) channel in a fading environment under a “low interference regime”. This capacity depends critically on a power loss parameter, alpha, which governs how much transmit power the CR dedicates to relaying the primary message. We derive a simple, accurate approximation to alpha which gives considerable insight into system capacity. We also investigate the effects of system parameters and propagation environment on alpha and the CR capacity. In all cases, the use of the approximation is shown to be extremely accurate. Finally, we derive the probability that the “low interference regime” holds and demonstrate that this is the dominant case, especially in practical CR deployment scenarios

Modelo de propagación para un entorno urbano que identifica las oportunidades espectrales para redes móviles de radio cognitiva

El pronóstico de ocupación del espectro radioeléctrico es útil en el diseño de sistemas inalámbricos que aprovechan las oportunidades en el espectro como la radio cognitiva. En este documento se propone el desarrollo de un modelo de propagación, que a través del pronóstico de la potencia recibida, identifica las oportunidades espectrales en canales de una red móvil celular para un entorno urbano. El modelo propuesto integra un modelo de propagación a gran escala con un modelo neuronal wavelet, que combina las pérdidas promedio con las pérdidas instantáneas. Los resultados del modelo, obtenidos a través de simulaciones, son consistentes con el comportamiento observado en experimentos de este tipo de sistemas inalámbricos.Abstract. The forecast of the radioelectric spectrum occupancy is useful for wireless systems designs that take advantage of spectrum opportunities, such as cognitive radio. In this document the development of a propagation model is proposed, that through the forecasting of received power, identifies the spectral opportunities in channels of a cellular mobile network for an urban environment. The proposed model integrates a large-scale propagation model with a wavelet neural model, which combines the average losses with the instantaneous losses. The results of this model, which are obtained through simulations, are consistent with the behavior observed experimentally of this class of wireless systems.Doctorad