Energy efficiency is a major concern for mesh nodes with limited power supply. So STDMA (spatial time division multiple access) is applied to reduce node’s power consumption in mesh networks. However, the energy cost was still high for solar panel applying with STDMA, due to the fixed slots and numerous start times of nodes. A VF-STDMA (variable frame in STDMA) is proposed based on STDMA protocol. The VF-STDMA dynamically changes the frame size and assigns timeslots to each link according