I. Introduction
WIRELESS personal area networks (WPANs) feature multi-users coexisting in a small area. Due to the short distance, users can communicate with each other directly in a peer-to-peer fashion without involving a relay node. In addition, due to the short distance, nodes may have harmful interference with each other. However, from a system point of view, having the nodes access the channel one at a time in a serial time-division multiple access (TDMA) manner may be a waste of resources due to the long waiting time each user experiences. The total network throughput may be decreased for not utilizing spectrum spatial reuse. The performance degradation can be significant when it comes to the millimeter-wave-based WPANs, since at the 60-GHz band, oxygen absorption peaks, and the transmission range is short; therefore, there is a lot of room for spectrum spatial reuse. To make efficient use of the radio spectrum, a rigorous treatment of the subject is necessary. This motivates the study of finding an optimal schedule for the maximum network throughput.