Multi-site MIMO (Multiple Input Multiple Output) is a key technology that will enable next generation cellular networks to achieve high throughput in cell edge areas. However, a multi-site single-user MIMO system is subject to performance degradation in terms of cell throughput due to the expense of additional assignments of radio resources to cell edge user equipment. This paper presents a BS-cooperation scheduling scheme for a multi-site single-user MIMO cellular system. The proposed BS-cooperation scheduling scheme aims to maintain cell throughput while improving cell edge user throughput. The proposed scheme employs two policies with respect to the assignment of radio resource to the user equipment with multi-site connection. One is to control the opportunities for radio resource assignment to user equipment with a multi-site connection to avoid the excessive assignment of radio resources and to maintain cell throughput. The other policy governs the decision as to whether the user equipment operates with a multi-site connection or not, making it possible for the multi-site connection to contribute to the improvement in user throughput in the cell edge areas. The simulation results show that the proposed scheme is effective from the perspective of both cell throughput and cell edge user throughput.