Sensor network terminals are installed in large numbers in the field and transmit data periodically by radio. Such terminals must be miniaturized, and save power so that each device can operate by battery for several years. As one way to satisfy these two conditions, in this research we propose a terminal design which eliminates the receiver circuit. Because there is no receiver circuit, circuitry can be miniaturized, and power can be saved because there is no need to consume power to receive signals. However, the terminals cannot perform carrier detection and reception acknowledgement because there is no receiver circuit. We propose following two new protocols to solve this problem. © 2010 IEEE.