How MTS using a solar-powered repeater launched 3G and LTE in the mountains

How to conduct communication of the third and fourth generation to where only 2G is running, due to the fact that the mountains interfere with the direct visibility of the base stations, and there is no necessary power capacity to install additional BS? Our expert Konstantin Kilber will talk about the relevant experience of the MTS company - using the example of installing an active repeater for a radio relay line in a small village in the Republic of Adygea in 2015. So, we give the floor to our specialist.

We faced a difficult task: to ensure the maximum throughput rate from the base station in the village of Guzeripl, the Republic of Adygea. This is a place at the foot of the Main Caucasus Range, at an altitude of 670 meters above sea level, with a population of just over 100 people.

The main problem was the mountains - they interfered with the direct visibility of radio relay stations (RRC), which are the transport component for base stations. Previously, a passive repeater was built (without active equipment): two radio relay antennas connected by a waveguide. The signal from the radio relay station (PPC 1) comes to one antenna, through the waveguide the signal enters the second antenna, then the signal goes to the second part of the radio relay station (PPC 2). The capacity of the radio-relay line with a passive repeater was no more than 30 Mbit / s, which is very small for modern communications. In this situation, only 2G base station can work, but with 3G and LTE, difficulties already arise.

To remedy the situation, we needed an active solar-powered repeater, since with the power in the mountains is a big problem. What is an active repeater? In fact, these are two transceivers with the help of which the capacity of a radio relay line is increased. By increasing the speed (bandwidth), we can use the Internet and watch videos. This is how the installation of the repeater to the network looks like.

It is an active repeater design of two solar panels, two batteries of 12 volts and two antennas, a transceiver unit and a compact box, inside which are controllers and batteries. An external power supply is not required to active repeaters, which allows them to be placed where there are problems with power supply and where it is unprofitable to draw a new power line. The device consumes only 5 watts. It turns out that the battery even without charging can work for half a month. The device has a controller that ensures that the battery does not overcharge (it makes it cut off) or does not go into a deep charge. The sun came out - went charge. This allows you to save the battery from failure. It turns out that there are two independent power supply systems that work in parallel. The vitality of the device is very good.

If we talk about panel antennas, then it is desirable that they be of good quality. There are several types of antennas, in particular, a polycrystal and a single crystal. The most productive - single-crystal. They are a bit more expensive, but their efficiency is higher, about 22%. They need perpendicular direction of sunlight. With diffused light, their performance decreases, and charging is not as intense as with direct rays.

As a result, after installing the active repeater, the bandwidth in Guzeripl grew 10 times - from 30 Mbit / s to 300 Mbit / s. Residents were, of course, very happy. This made it possible to connect the category of "VIP-clients" - who need access to the Internet at high speed.

Another distinctive feature of the active repeater - its installation does not require large human resources. Although you only need to understand that they are installed, as a rule, in poorly populated places, so it is important to take care of the anti-vandal arrangement. Of course, not at all to be saved from vandals. Even well-protected base stations are cracked, what to say about the active repeater. In the village of Guzeripl we set up a small turret (16m) and fenced it with an iron fence with barbed wire.

If we talk about the reliability of active repeaters, then it suffices to say that we installed our equipment on June 1, 2015, and it still works without complaints. They survived both winter and summer, spring and autumn - and the emergency recovery team never went there. This means that, firstly, the engineers did everything qualitatively, and secondly, the equipment proved its reliability, and thirdly, no hacks occurred.

If we talk about the shortcomings of the device, they are few. For example, it does not support remote parameter control. That is, you can not see remotely - the repeater is working or not. We have to judge by speed - if it “fell” or the connection disappeared altogether, then the active repeater failed. Another disadvantage is the possible "pollution" of the panels. Or from dirt, or from sticking of snow. That is, it is still impossible to completely leave such equipment unattended - at least once every three months you need to visit, wipe the panels and look at the general physical condition. But there are definitely more advantages. Especially payback, given that we do not need to pull power lines - and this pleasure is very expensive.

Installation of active repeaters

There are two ways to mount. The first option is the installation of a square or triangular iron construction 1-2 m high on a reinforced concrete base. Equipment and antennas are placed on a metal structure. This method is more economical.

The second option involves the construction of the tower in places where it is difficult to achieve direct visibility due to topography or vegetation. Here is a look at a small amateur video from the installation of a repeater in the village of Guzeripl.

For greater reliability of the network, we are doing parallel and active repeater, and passive. It turns out that the radio-relay station operates on two RRL trunks. When everything works properly, the network works through an active repeater, and the second passive - in reserve. If for some reason the active repeater fails, the signal goes to the parallel trunk - where the passive repeater works. In the case of a transition to a backup trunk, the transmission rate naturally drops from 300 Mbit / s to 30 Mbit / s until the active repeater is restored. By the way, our emergency recovery team has all the spare parts (spare parts) for repairing repeaters. Up to the solar panels, the transceiver itself and the batteries. As a rule, apart from the transceiver and the battery, there is nothing to break down. Solar panels have a mean time to failure of more than 20 years.

Having received a positive experience, we decided to continue to implement active repeaters. We bought about 20 sets, 6 of them have already been launched: in the Krasnodar Territory and in the Republic of North Ossetia - Alania. Ahead of the launch of other kits.