Time Delay Estimation Based on Multi-band Multi-carrier Signal in Multipath Environments

The matched filter is the most common approach for time delay estimation and ranging in positioning systems. The accuracy is mainly determined by the signal bandwidth and multipath propagation condition. Instead of occupying an enormous signal bandwidth, aggregating multiple signal bands, which are transmitted either simultaneously or sequentially from the same transmitter, can still provide a very high time resolution due to its large virtual signal bandwidth. This paper discusses time delay estimation based on multiband signals, considering precision, range ambiguity and resistance to multipath. Combining carrier phases from different bands, which are physically not perturbed by a sampling frequency offset, can also mitigate the bias of time delay estimation due to the sampling frequency error. Simulation results show that using two groups of multiband signals, which are sparsely placed in the signal spectrum, can significantly improve the accuracy of time delay estimation in the presence of multipath and sampling frequency offset.