In this paper, we propose an efficient Channel Time Allocation (CTA) method for multi-hop communications in IEEE 802.15.3 high-rate WPAN mesh networks. The proposed CTA allocation method allows sufficient CTA allocations for devices and child PicoNet Coordinators (PNC) while considering the fairness between these devices. In this method, the child PNCs are granted larger CTA allocations than DEVs taking into consideration the dynamicity of the superframe length. Additionally, it ensures minimized delay between CTAs granted to isochronous streams of a device in subsequent superframes. We evaluate the performance of the proposed technique via simulations. The proposed technique achieves good satisfaction for a maximum number of devices.