Abstract: Interferences and collisions among the signals of different beacons，to indoor location system with the decentralized architecture for wireless sensor networks，become the one of the important factors that decreases location accuracy.In this paper，an improved method to generate the random-delay-time is presented，and it can reduce the radio frequency collisions according to the relationship between beacon numbers and characteristic of radio frequency.In addition，serious interferences are decreased by using decreased-weight method at the same coverage of ultrasound from deferent neighbor beacons.To obtain the high location accuracy，an algorithm is also proposed to choice the proper distance information.

Key words: Wireless Sensor Network（WSN）, Time Difference of Arrival（TDOA）, indoor location, radio frequency, ultrasound

摘要： 在无中心构架的无线传感器网络室内定位系统中，参考节点间的信号相互之间存在的干扰和冲突成为影响定位精度的重要因素之一。文中根据随机延迟时间与参考节点数量及射频发射特点之间的关系，改进了可以减少射频信号冲突的随机延迟方法。另外，设计了参考节点间的监听并加权递减的方法，有效地减少了邻居节点间超声波在同一覆盖区出现严重干扰的现象。同时，为了提高待测节点的位置计算精度，设计了合理的距离信息选择算法。

关键词: 无线传感器网络, 到达时间差, 室内定位, 射频, 超声波