Comprehensive study of device positioning accuracy in LTE networks under non-line-of-sight conditions

Today, the overwhelming radio coverage in megacities is provided by fourth-generation 4G LTE networks in conditions of no direct visibility, therefore, despite the development of fifth-generation 5G NR networks, the task of a comprehensive study of the accuracy of positioning devices in LTE networks remains relevant and in demand. A sufficient number of studies by leading foreign scientific schools are devoted to this issue, but in the domestic segment, as far as the authors know, no works have been published yet that reveal a comprehensive accounting of all factors. The purpose of this study is to develop a methodology for establishing the limits of the accuracy of positioning devices in LTE networks, taking into account the impact of multipath, interference and bandwidth limitations on a typical hexagonal cellular structure of a radio access network fragment in accordance with the recommendations of 3GPP TR 36.942 report. The analysis includes modeling of typical multipath channels (EPA, EVA, ETU) describing operation in conditions of no line of sight, implementation of TOA estimation methods, such as multipath channel error envelope, first peak estimation, average TOA accuracy estimate based on power delay profile and based on time delay error histogram using maximum likelihood method, as well as establishing the Cramer-Rao lower bound of both primary TOA measurements and coordinate estimates resulting from secondary TOA processing using OTDoA method. The obtained results can be used in configuration of existing, as well as in construction of prospective LTE networks and corresponding positioning algorithms to improve the accuracy of geolocation in real operation conditions. The developed methodology can also be used in next-generation 5G/6G networks.