A multiple-input, multiple-output (MIMO) communication system is configured to utilize a variable slot structure. The system includes multiple terminals and at least one base station configured to communicate with the terminals. The base station is operative to determine mobilities for respective ones of the terminals, to arrange the terminals into groups based on the determined mobilities, and to utilize at least first and second different slot structures for communicating with the terminals of at least respective first and second ones of the groups. The system may be, for example, a multi-user MIMO system in which the multiple terminals comprise autonomous single-antenna terminals.