一种TOA联合同步与定位的CWLS算法

Constrained weighted least squares algorithm for TOA-based joint synchronization and localization

在基于到达时间定位中,针对目标节点与传感器锚节点之间存在时钟偏差而导致定位性能下降的问题,提出了一种时钟同步与目标定位联合估计算法。该算法通过引入辅助变量将非线性量测方程伪线性化,并建立代价函数;然后利用变量之间的关系构造约束条件,将原定位问题转换为约束加权最小二乘问题;最后利用拉格朗日乘子法得到目标位置和时钟偏差的闭式解。理论分析和仿真实验表明,所提算法的定位性能逼近克拉美罗界,优于现有算法。

The asynchronous problem between source node and sensor anchors seriously reduces the positioning accuracy in time-of-arrival(TOA) based localization. To solve this problem,a novel algorithm for jointly estimating the clock bias and the position of a source node is developed in this paper. By introducing an intermediate variable,the proposed method first converts the nonlinear TOA equations into pseudo-linear ones,on the basis of which a cost function is constructed. Then,utilizing the relationship between the unknowns and the intermediate variable as the constraint condition,a constrained weighted least squares problem is formulated. Finally,by solving the problem with the technique of Lagrange multipliers,the closed-form solution is obtained. Theoretical analysis and simulation results indicate that our algorithm can reach the Cramer-Rao Lower Bound(CRLB) and perform better than the existing methods.