Tower of vision: Russia has learned how to determine geolocation without GPS

Russian engineers have developed a way to determine the coordinates of mobile devices without using satellite navigation. The method of specialists from the Moscow Institute of Physics and Technology (MIPT) calculates the location based on the parameters of the base station signals, which the terminals measure normally. During the automotive tests, the developers obtained an accuracy of 3 to 20 m. No additional equipment is required for the operation of the system. Experts believe that the technology can become a backup way of positioning where GLONASS and GPS signals are unavailable or unstable. However, the effectiveness of the method directly depends on the density of the cellular network coverage.

Determining coordinates based on signal strength

Specialists from the Moscow Institute of Physics and Technology have developed a new technique that allows you to determine the coordinates of a mobile phone without using satellite systems such as GLONASS or GPS. At the same time, the technology provides comparable accuracy. The standard data exchanged between the devices and the base stations is sufficient for its operation. Basic calculations are made based on the signal strength of the mobile network. This approach makes it possible to calculate the geolocation of a moving object.

"The mobile terminal continuously measures the signal parameters from base stations, which is a standard function that works regardless of the availability of satellite signals," said Grigory Seregin, director of the Research Center for Mobile Communication Components and Manufacturing Technologies at MIPT. — We conducted long-term experimental studies when driving a modem in a car and showed that these measurements are enough to build a model of radio wave propagation and determine the coordinates of an object with an accuracy of 3 to 20 meters, which is comparable to the results of satellite navigation systems even without a SIM card installed. In fact, we use the existing infrastructure of communication networks as a navigation one.

The key parameter in the operation is the power of the received cell tower reference signal (RSRP). Unlike the indicators characterizing the quality of a radio channel, it is directly related to the level of the received signal and therefore can be used to build a model of radio wave propagation. This parameter is selected as the source data for calculating coordinates.

Technology implementation

Since the signal strength depends not only on the distance to the transmitter, but also on the characteristics of a particular tower and propagation conditions, calibration is performed for each signal source: an individual attenuation model is built and the characteristic measurement error is estimated.

— During operation, the terminal simultaneously receives RSRP values from several stationary sources with known coordinates. The algorithm compares them with the calculated model and uses mathematical methods to determine the most likely position of the object. At the same time, the algorithm is able to automatically reduce the impact of abnormal measurements and unstable sources on the data," said Ekaterina Yuneva, CEO of MIPT Telecom.

The approach combines receiving information from a cellular network, analyzing radio signal parameters, and calculating object coordinates in real time. The work shows that the standard measurements of a mobile terminal can be used as a basis for positioning tasks and creates the basis for the development of alternative navigation technologies based on the existing infrastructure of communication networks.

The topic of coordinates: which countries have their own GPS analogues

And what are the prospects for modern satellite global positioning systems?

In the future, the development can be used to determine the location of people and various types of land transport, according to its authors. Possible scenarios include tracking railway trains, trucks on long—distance routes, unmanned vehicles, as well as quarry and other equipment at mining enterprises.

According to Denis Kuskov, CEO of the information and analytical agency TelecomDaily, the proposed technology may well replace satellite navigation where there is no access to it.

— The best option for geolocation is GPS and GLONASS, which determine it with an accuracy of several meters. The method of determining coordinates based on the location of base stations used to work with a higher error. But since in some cases it is impossible to use satellites, we have to invent something new. And the ability to measure the coordinates of a moving object expands the capabilities of this technology," said Denis Kuskov.

The main value of the approach lies in the stability of navigation, according to Oleg Yablokov, NTI expert on wireless communications. The satellite signal disappears in tunnels, deep quarries and dense urban areas, it can be silenced or replaced. The cellular network often continues to work in such conditions, and a smartphone or modem is constantly measuring its signal. To determine the coordinates, it will be enough to programmatically process the already available data, without installing additional equipment. The predictive algorithm allows you to get a continuous track of movement between individual measurements, which is especially important for transport.

— Location detection over a cellular network has been known for a long time, and its main limitation is related to accuracy. It depends on the density of base stations: there are many in the city, and noticeably fewer on long-distance routes and in remote areas. Therefore, in the coming years, it is logical to consider this method as a backup channel complementing satellite navigation and inertial sensors," Oleg Yablokov said.

In his opinion, the most interesting application is in mining enterprises, where they are increasingly deploying their own LTE networks with dense and controlled coverage. The next step should be field testing with an assessment of accuracy in real-world operating conditions.