基于RSSI的定位，已知发射节点的发射信号强度, 接收节点根据接收信号的强度, 计算出传播损耗, 利用理论的或经验的信号传播模型将传播损耗转化为距离, 然后再计算出节点的位置-RSSI-based positioning, known to launch the node transmission signal strength, the receiving node according to received signal strength, transmission loss calcula