The main use of wireless sensor networks (WSNs) is to collect information for many different applications such as environment and habitat monitoring, military purposes, structures protection and many other applications. The sensor nodes used in the network can sense and transmit the data wirelessly. The primary benefit of WSNs is that it enables information gathering without direct human efforts. In addition, these sensors are usually battery-powered and, in most cases, it is not practical to recharge or to replace the batteries of these sensors after deployment (unattended scenario). Therefore, it is important to prolong the lifetime of the WSN and to ensure that the application can last as long as possible. IEEE 802.15.4 standard is one of the prominent protocols for WSNs. However, it assumes that the sensor nodes operate in an attended scenario. In this research, we seek to implement IEEE 802.15.4 in an unattended scenario. Therefore, to achieve that, cluster head rotation is needed to avoid the problem single point of failure (i.e. when the battery of the cluster head is depleted, all the nodes in the cluster will not be able to forward their data any more). To maintain the features of this protocol while implementing it in an unattended scenario, we propose to use a long fixed hyperframe for periodic setup phase. This hyperframe contains smaller variable superframes. In this way, some applications used in an unattended scenario may exploit the characteristics of IEEE 802.15.4 standard. © 2011 IEEE.