In order to analyze and design mobile communication systems having multiple transmit and receive antennas, a statistical multiple-input-multiple-output channel model that characterizes the received signal in both spatial and temporal domains is needed. In this work, we derive a correlation function that takes into account both the time lag, the base station antenna separation, and the mobile terminal antenna separation. The mobile terminal is assumed to be surrounded by a ring of scatterers. The properties of the space-time correlation function in some practical cases are also analyzed.