Sensor network terminals are installed in large numbers in field, and they transmit data periodically by radio. Such terminals must be miniaturized, and power must be saved so that each device can be operated by battery for several years. As one way to satisfy these two conditions, in this research we propose a terminal design that 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.1. Terminal transmission times are randomized to prevent frequent collisions between specific terminals due to the lack of carrier detection. 2. Since all packet losses due to collision cannot be prevented with (1), data from a number of past transmissions is included in each packet so that a later packet can provide transmission data even if a packet is lost.In this report, we describe the proposed protocol, and evaluate its performance by simulation. Furthermore, we actually prototype the system and evaluate the prototype's performance.