一种正交频分复用系统多径时延估计模型与算法

Multipath Delay Estimation Model and Algorithm in OFDM Systems

针对正交频分复用(OFDM)系统的时延(the time of arrival,TOA)估计未充分利用OFDM信号的时频特性及其精度较低的问题,根据OFDM信号的时频特性提出一种基于频域相偏的多径时延估计模型(Multipath Delay Estimation Based on Frequency Domain Phase-offset,FDP-MDE).并在此基础上,结合LTE(Long Term Evolution)系统的实际特点提出一种分组联合时延估计算法(Grouped Joint Time Delay Estimation,GJ-TDE).该算法首先将OFDM系统的时域接收信号转换为频域信号,然后对频域信号采样分成多组低维的接收数据矩阵并利用各采样数据矩阵组分级估计时延,最后取各时延估计值的平均作为定位时延值.仿真结果表明:在信噪比(SNR)为0dB、采样间隔为8的条件下,GJ-TDE算法的均方根误差(RMSE)比基于时域同步的Mensing算法降低了5.503 4m.

The precision of the TOA （the time of arrival） estimation is low because it underutilizes the time-frequency characteristics in OFDM （orthogonal frequency division multiplexing） systems. To solve this problem, in this paper, a FDP-MDE （multipath delay estimation based on frequency domain phase off- set） model was proposed. Besides, a GJ-TDE （grouped joint time delay estimation） algorithm was pro- posed according to the actual features of the LTE system. First, the time domain signal was converted into the frequency domain signal. Then, it was sampled into the low-dimensional received signal matrix groups, which were used to estimate the time delay. Finally, the mean of all the delay estimation was taken as positioning. The simulation results show that the root mean square error （RMSE） of the GJ-TDE algorithm is 5. 503 4 m smaller than that of the synchronization Mensing algorithm when the $NR is 0 dB and the sampling interval is 8.