IEEE 802.15.4 is a global standard designed for the low power consumption, low cost, and low data rate. Thus, this standard is advantageous to implement Ubiquitous Sensor Network (USN). However, researchers do not have been studied to employ cooperative communication in this system. Cooperative relaying system has been shown to help the destination to get the spatial diversity. It is possible to more reliable transmit and to reduce the consumption energy. It is useful for battery powered nodes. Therefore, the authors propose the IEEE 802.15.4 utilizing cooperative communication system that can efficiently transmit and save energy. They call this system as ZigBee-based cooperative communications.