In this letter, we tackle the channel contention and hidden terminal problems of asynchronous duty-cycle MAC protocols under heavy traffic scenario. To resolve the problems, we design a queue-based burst transmission MAC protocol (Q-BT), which couples burst (and fast) transmission and asynchronous duty-cycle features together by using queue length information. We evaluate its performance in a multihop testbed, which shows that our proposal improves packet reception ratio and duty-cycle performance by 70.2% and 59.1%, respectively, at a maximum compared to BoX-MAC (i.e., the default MAC in TinyOS).