The authors propose two link-layer reliable broadcast protocols for wireless sensor networks based on IEEE 802.15.5. They compare them in terms of energy consumption. By including both positive and negative acknowledgement, their second proposed scheme can effectively reduce the number of unnecessary error control messages and, thereby, significantly reducing the unnecessary power consumption relative to the first scheme. Also, they provide an analytical framework for the evaluation of different reliable broadcast techniques. Simulation results show that Scheme 2 achieves energy savings of up to about 85% compared to Scheme 1.