An improved approach, called receiver only synchronization (ROS), relative to timing synch protocol for sensor networks (TPSN) was devised based on a two-way timing message exchange mechanism between two nodes. In ROS, all the nodes in their transmission range overhear the messages and adjust their clock parameters without having to communicate by themselves, hence saving a lot of energy. In this paper, we are proving that in ROS, one-way timing message transmission from the root node to the neighboring nodes located within its transmission range is superior to the two-way timing message exchange. Also, we are showing that choosing the more accurate model instead of the linear regression model yields further performance gains for the clock parameters estimation.