Abstract: This experiment analyzes the properties of RSSI for indoor 3D space WSN positioning system with the reference node upside down on the ceiling. Experimental results show that, compared to the reference node fixed in a horizontal plane, placing the reference node upside down on the ceiling has better concentration of the RSSI. It is possible to further improve the concentration of the RSSI by adjusting the transmission power of the sensing node according to the size of the three-dimensional indoor space. It can be judged by the standard deviation whether someone or obstacle is around the node. RSSI-based ranging technology is feasible in the indoor three-dimensional space positioning system.

Key words: Received Signal Strength Indication（RSSI）, ceiling, transmission power, indoor positioning system, three-dimensional space, wireless sensor network

摘要： 实验分析了参考节点倒置在天花板时室内三维空间无线传感器网络定位系统RSSI的性质。实验结果表明：相比于参考节点固定在水平面，将参考节点固定在天花板，RSSI有更好的集中性；根据室内三维空间的大小调整传感节点的发射功率，可以进一步提高RSSI的集中性；人员在发射节点附近会对RSSI产生影响，通过标准差大小可以判断节点附近是否有人或障碍物；在室内三维空间定位系统中采用基于RSSI的测距技术是可行的。

关键词: 接收的信号强度指标（RSSI）, 天花板, 发射功率, 室内定位, 三维空间, 无线传感器网络