Multiple-input multiple-output (MIMO) mobile ad hoc networks have been receiving increased attention in both commercial and military applications. Just as in cellular networks, MIMO technologies can benefit ad hoc networks by providing the diversity and capacity advantages as well as the spatial degree of freedom in designing the media access control (MAC) protocol. However, one fundamental issue of MIMO mobile ad hoc networks is how to accurately model the impact of spatial/temporal channel correlation in the mobile-to-mobile communications environment. In such a channel, line-of-sight (LOS) components and different scattering environments will affect both ergodic capacity and average capacity fading duration of the MIMO system. In this paper, based on the double-ring scattering model with LOS components we suggest a sum-of-sinusoids MIMO mobile-to-mobile channel simulation method, which can characterize the spatial/temporal channel correlation and Rician fading effect. Our numerical results show the ergodicity of our proposed channel model, correctness of the analytical channel correlation, effect of spatial correlation on channel capacity, impact of the number of antennas and scatterers on capacity, capacity distribution, and level crossing rate (LCR) and average fading duration (AFD) of MIMO Rician channel capacity. We also show the impacts of Rician factor K on channel capacity, probability density function (PDF), LCR, and AFD.