Low-power and lossy networks built in industrial environments may be required to handle large amounts of wireless communication traffic. The IEEE 802.15.4e TSCH MAC protocol (TSCH) is widely used in this environment. TSCH uses slotted time and channel hopping. In the TSCH network, a slotframe composed of a timeslot offset and channel offset operates repeatedly. Each node in the network operates according to the cells allocated in the slotframe, and the performance of the TSCH network is very different depending on the method of scheduling these cells. We propose an improved link-based autonomous cell scheduling scheme for TSCH, called IM-LAS, which makes the size of the slotframe different for each wireless link and activates a cell without additional communication overhead when there is a traffic request. In the experiment using hardware devices, IM-LAS showed better performance with up to 43% higher PDR and 67% lower latency than ALICE, and up to 83% higher PDR and 92% lower latency than Orchestra in high-traffic environments.