Smart home is getting popular. An essential element of smart home is sensor network to convey environment information to the control station. There have been many communication protocols for this sensor network. One problem of previous protocols is unbalanced energy consumption among sensor nodes. Even though they tried to overcome energy unbalanced consumption, they could not solve this problem satisfactorily yet. In this paper, we find that basic reason for this unbalanced energy consumption is that there is normally one base node. Because of this architectural problem, the nodes around this sink node lose their energy more easily relative to other nodes. So, we propose the sensor network architecture with 2 base stations, and its corresponding communication protocol.