One of the fundamental operations in the wireless network is broadcasting, which is widely used to disseminate information throughout the network. Flooding is a simple method to realize broadcasting. However, flooding will incur a large number of redundant retransmissions, leading to low transmission efficiency. In this paper, we propose an optimized broadcast protocol (OBP) to improve the transmission efficiency. In OBP, each node calculates the retransmission locations based on a hexagon ring pattern in order to minimize the number of retransmissions. Only the nodes nearest to the calculated locations need to retransmit the packet. As shown by analysis, the transmission efficiency bound of OBP is 0.55, which approximates the theoretical optimal bound 0.61 by a ratio of 90%. We also compare OBP with a related protocol called OFP in terms of transmission efficiency and reachability.