This paper proposes the Virtual Time-slot Allocation (VTSA) scheme for throughput enhancement to realize a Gbps-order wireless personal area network (WPAN) system in the millimeter-wave realistic residential multipath environment. In the conventional time division multiple access (TDMA) WPAN system, the network controller, known as the piconet coordinator (PNC) allocates time-slots for devices in the network to establish communication links, one time-slot for one communication link. In this paper, the proposed VTSA scheme enables a single time-slot to be reused for multiple communication links simultaneously, thus significantly increase system throughput. However, this causes co-channel interference (CCI) among the communication links occupying the same time-slot. The proposed VTSA scheme is therefore designed to optimize the throughput-CCI tradeoff, taking advantage on the large path loss among communication links, a unique characteristic in the millimeter-wave band. The proposed scheme is a cross layer design involving the medium access control (MAC) layer and the physical (PHY) layer. The MAC layer is responsible for executing the VTSA algorithm, a protocol that manages the rules and procedures for throughput-CCI tradeoff in reusing the time-slots. Two time-slot reuse methods are proposed and compared in this paper, namely the minimum-CCI slotting method and the random slotting method. The PHY layer is responsible for constantly measuring and reporting the CCI due to time-slot reuse in different millimeter-wave channel conditions. As a result, it is found that the VTSA scheme is capable of increasing the system throughput as much as approximately 30% in the additive white Gaussian noise (AWGN), line-of-sight (LOS) and non-line-of-sight (NLOS) multipath channel. It is also found that the minimum-CCI slotting method has 10% better performance as compared to the random slotting method.