Development of SDR-based network positioning technology. LTE reference signals generation

Abstract

An analysis of the state of the problem of building prototypes of fourth and fifth generation network positioning technology, using the approach of model-based design and software-defined radio SDR (Software-Defined Radio) according to open foreign sources showed the high actuality and relevance of this direction. At the same time, insufficient attention is paid to this area of research and development in native sources. This paper proposes the layout of the developed SDR demonstrator of network positioning technology. The task of developing the demonstrator is to substantiate technical solutions to improve the accuracy of determining the location of devices in modern and future communication networks in the absence of signals from the global navigation satellite system. The purpose of using SDR technology for network positioning tasks is to get the opportunity to improve the developed technical solutions in the process of their actual operation. Developed demonstrator includes the following subsystems: a subsystem of eNB base station prototype with known coordinates that implements the generation and transmission of reference signals of the LTE standard; prototype of the user equipment UE, which implements the reception and processing of the reference signals of the LTE standard, as well as the primary processing of measurements using the reference signals of the LTE standard; eNB base station prototype synchronization subsystem, which implements the distribution of a timestamp signal; the SDR demonstrator control subsystem, which implements the control of the procedures for collecting primary measurements of network positioning and their secondary processing with the resulting estimate of the coordinates of the user equipment UE. Also, this article describes the results of software-hardware implementation and experimental testing of the LTE reference signal generator on USRP SDR devices in Matlab environment. The procedure for generating reference signals is uniquely determined by the cell identifier, and the generator itself is an integral part of the layout of the SDR network positioning technology being developed. Experimental testing of the reference signal generator in laboratory conditions using objective control tools showed correct determination of the group identificator and cell identificator within group, which uniquely determine initialized cell identifier.