Channel Models for Mobile-to-Mobile Cooperative Communication Systems: A State of the Art Review

This article provides a tutorial survey on channel models for mobile-to-mobile (M2M) cooperative communication systems. The spotlight is on nongeometrical stochastic channel models assuming non-line-of-sight (NLOS) and line-of-sight (LOS) propagation conditions. Furthermore, the studied systems range from very simple configurations, such as a single relay dual-hop arrangement with no direct link between the source mobile station and the destination mobile station, to quite demanding situations characterized by dual-hop multirelay configurations, where the direct link is unobstructed. It has been shown that M2M cooperative channels are strongly dependent on the systems' topology. They can exhibit more severe fading than classical Rayleigh channels with completely different first- and second-order envelope statistics.