无线传感器网络节点通信与定位综合信号设计

Node communication and localization integration signal design in wireless sensor network

针对无线传感器网络中依赖于接收信号强度指示(RSSI)的极大似然定位算法易受环境噪声影响的问题,设计传感器节点的通信与定位一体化信号。对锚节点的激励信号设置较小的载波频偏并设计激励信号,将传输的数字序列与距离信息调制到一个信号星座图中,未知节点通过对信号的信息解调可以初步计算未知节点与锚节点间的距离。未知节点将初步的估计距离信息发送给锚节点来调节信号频偏,再次精细距离的测量准确度,最后采用极大似然法直接计算未知节点的位置。该方法是在一体化的通信信号中解调数字序列和距离信息,避免再将信号强度转化为距离的过程。仿真结果表明:节点的通信与定位综合信号可以一定程度上提高定位准确度,在不同的节点数、锚节点数、通信半径和信噪比下定位误差分别为22.44%、21.15%、19.18%和21.79%,可为节点定位提供一个简便的计算方案。

In order to solve the problem that the maximum likelihood localization algorithm, which depends on received signal strength indication(RSSI), is easily affected by environmental noise in wireless sensor network(WSN), communication and localization integration signal for sensor nodes is designed. A small carrier frequency offset is set for the excitation signal of the anchor node, and the excitation signal is designed to modulate the transmitted digital sequence and distance information into a signal constellation. The unknown node can calculate the distance between the unknown node and the anchor node from the signal informationdemodulation. The unknown node sends the preliminary estimated distance information to anchor nodesfor adjusting the frequency offset, which refines the measurement accuracy of the distance. Finally, the maximum likelihood method is used to calculate the position of the unknown node directly. The method demodulates digital sequence and distance information in the integrated communication signal to avoid the process of converting signal strength into the distance. The simulation results show that the integrated signal of communication and localization can improve the positioning accuracy to a certain extent, which provides a simple calculation scheme for node localization. Under different node number, anchor node number,communication radius and signal-to-noise ratio, positioning errors are 22.44%, 21.15%, 19.18% and 21.79%respectively.