This paper presents a MIMO system scheme which is combined with STBC and V-BLAST. It can balance spatial multiplexing gain and diversity gain. Then, according to theory, a result is provided by a simple simulation analyze. In addition, for the application to ad hoc networks, a CSMA/TDCA protocol, which avoids the collision through a mode of time slot assignment without effecting data transmission, is offered. Finally, a virtual central base station theory, which provides convincing support for applying this combining system to ad hoc networks in the abstract, is proposed.