Maximum likelihood geolocation in LTE cellular networks using the timing advance parameter

Wireless geo location is an increasingly relevant area of research as cellular technology becomes ever more ubiquitous. In this work we consider the timing advance parameter in Long Term Evolution cellular networks to this end. We also evaluate a previously introduced method of position estimation augmentation called Cellular Synchronization Assisted Refinement (CeSAR). We first develop the concept of geometric dilution of precision and the Cramer-Rao Lower Bound (CRLB) to motivate an intuition for positioning accuracy. We then derive an exact maximum likelihood estimator (MLE) for TA-specific position estimation. While the exact MLE proves to be computationally difficult, it is shown to be equivalent to the MLE in the general case of Gaussian noise. This equivalency is then used to propose an approximate MLE (AMLE). Through simulation, the AMLE is shown to meet the CRLB. Real-world data that includes urban, suburban, line-of-sight, and non-line-of-sight channels are also presented and used to build a realistic model of the TA-specific channel. This model is then used to evaluate the performance of the AMLE and CeSAR in non-line-of-sight and line-of-sight conditions. Our results suggest that the proposed method may be appropriate for meeting the Federal Communication Commission's E-911 requirements.