Cooperative diversity techniques have been proposed to improve the performance of modern wireless mesh networks. The increased demand for bandwidth has led to the employment of frequencies above 10 GHz, where the dominant fading mechanism is rain attenuation. The rain attenuation induced on a microwave path is usually modelled as a lognormal random variable. In this paper, the outage performance analysis of a cooperative diversity system operating at frequencies above 10 GHz is presented, employing spatially correlated lognormal fading channels. The final destination node combines the direct link signal with a signal received through a regenerative (decode-and-forward) relay using selection combining. Various multiple-access protocols are considered, while energy and spectral efficiency are investigated. Extended numerical results present the impact of various operational, geometrical and geographical on the system performance. Finally, comparison with an effective direct link highlights the gain of cooperative diversity techniques.