Nextivity Cel-Fi RS2 black - intelligent 3G signal amplifier

Surely each of us has repeatedly encountered poor communication quality - a low 3G signal. For some, this problem is uncritical, but there are times when a stable connection is vital. If this is your case, I recommend reading this article.

Coverage in Russia still leaves much to be desired. This is especially true of 3G networks. Even on the streets of the city, the 3G phone does not always catch on, not to mention the offices in high-rise business centers, all kinds of basement and garage rooms and other reinforced concrete structures. The central part of Russia is mostly flat, and outside the city the signal of the operator spreads without significant interference, the only question is the distance to the base station. However, in places with hilly or mountainous terrain or with dense urban development, even the proximity of the BS does not guarantee a sure reception.
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Many work remotely, resting from the city in country houses and in country houses. And in this case, a prerequisite for quiet work is the availability of quality coverage, as well as a stable and fast Internet channel.

In this article I want to introduce you to the Nextivity Cel-Fi RS2 black subscriber terminal. This is a relatively new solution used by major international operators: Vodafone, AT & T, T-Mobile, Orange group, etc., as well as approved and certified in Russia. It serves to increase the zone of confident reception and transmission of voice and data using 3G technology.


Options for improving coverage is not so much known. To begin with, we will look at common solutions so that it becomes clear why there is a need for something new.

Standard Wired 3G Repeater / Amplifier

When using it, firstly, it is necessary to understand the topic in great detail. The fact is that a bidirectional amplifier increases the network noise level (interference), making it difficult for other users to access the network. To minimize this effect, you have to read a lot, google, check. Secondly, it will be necessary to buy the right components - an external and internal antenna, a suitable RF cable, connectors and adapters. Then mount all this, properly orient the antenna, to achieve an acceptable signal level. And, thirdly, there are practically no ready-made kits for sale, and there are no certified solutions either. The reason is that such systems spoil the signal to operators, change the coverage map. Due to the fact that such repeaters have a fixed gain, regardless of the desired signal level and often exceeds the base station. In addition, the signal transmission up (towards the BS) is continuous.



As a result of such installations, worse, the following sad situations arise: those. The operator’s department records the impact of unacceptable radio interference on the base station and initiates a request for verification of the legality of the operation of radio electronic equipment (RES) to the Federal Service for Supervision of Communications, Information Technologies and Mass Communications (Roskomnadzor). The Radio Frequency Center, in turn, conducts search and direction-finding activities, analyzes the electromagnetic environment and identifies that the source of radiation is the repeater. Next, the installation site and the owner of the repeater are determined, and since the latter does not have permission to use radio frequency channels and does not have a certificate of registration of such a repeater, Roskomnadzor issues a decision on an administrative offense in the field of communications. The resolution obliges the perpetrator to pay the fine and take measures to eliminate the violations, which implies a complete disconnection / removal of the repeater.

Operators also have professional repeaters. They require a lot of settings and technical approvals. Their cost is lower than that of the base station, but still these are amounts of the order of 100-300 thousand rubles. Therefore, they put such only on large objects and key customers (who have high monthly charges).

Dance with a tambourine around a 3G modem

Remote directional antenna, focusing antenna, transfer of the modem to the roof (at the cottage), etc. It might look something like this:



Here are some DIY examples.

Judging by the reviews, the focusing of the “at random” signal is almost hopeless. It requires painstaking calculations. And external antennas for a modem, again, are difficult to install and configure. In addition, we obtain only a limited version of the implementation of the method number 1 - exclusively for the Internet. The maximum that can be done is to install a 3G rotor and distribute the Internet via Wi-Fi. But talking on the phone is not talking, and if you have the same bad level of 2G and 3G - this solution will be half-hearted.

However, who cares, the process is described in detail in the links above, and the authors are pleased with the result.

Femtocell - "its" miniature base station

It can be useful in a city where it is necessary to provide an office or any other room with high-quality voice communication. For the 3G Internet, the thing can be said to be useless, because the femtocell itself requires a stable Internet channel of 3-7 Mbit / s. Well, its installation must be coordinated with the operator, and for this you need to be a corporate client. It should be added that the femtocell has a rigid geographic “binding” to a specific address, in connection with which there is no possibility of free movement. And if you have confidential information stored in your local network, the channel to the operator potentially reduces the data security. The advantage of femto cells is the complete absence of the need for a base station signal.



This is where common ways of improving the 3G signal end up. And now, knowing the theory of the question, we can see what kind of device the Nextivity company developed.

Nextivity Cel-Fi RS2 black

In short, this is a wireless two-way amplification system of the 3G signal on the subscriber's side, which does not require tuning, does not interfere with other users and increases the capacity of the cellular network.

Outwardly, it looks like two black boxes, though quite stylish, in the spirit of Apple. The kit consists of receiving and transmitting modules that communicate with each other over Wi-Fi (hence, apparently, the name of the device - Cel-Fi). The receiver, the so-called Window Unit, is installed in the zone with the best level of the 3G signal, most often closer to the window. The transmitter can be attributed to a distance of 25 meters (in open space) and positioned so as to cover the maximum, or simply the problem, zone in the room. Moreover, the task of finding the optimal place is very simple and does not even require a basic knowledge of the theory. Probably easier to see once.



Now let's take a closer look at the principle of operation of the device, applied technologies, characteristics and features.

Equipment

The device comes in a weighty box. You can't call it small and inconspicuous - the dimensions of the receiver are 20x15 cm, the transmitter is slightly smaller. I did not disassemble them, but the feeling that inside the housings of both modules is pretty empty. Alas, with all the manufacturability of antennas, their size matters.



In the box are:

• Device reception "Window Unit"
• Coverage Unit device
• Two identical power adapters
• Installation and Connection Guide

Everything is underlined simply, nothing superfluous.



On the front panel of the "receiver" power indicator and 5 LED indicators of the signal level in green. At first glance, a strange decision - it would be enough to do with one’s usual, with 5 stripes. It is most likely explained by the fact that these blocks stand at decent distances, and in case of changes, it is enough for the user to look from afar and fix the indication.



Below there is a Micro SD slot (apparently, for setting up for an operator, as described below), an SMA port for an external antenna, a power connector, a reset button.



The RS1 model had more slots for hanging on the wall. RS2 doesn't have them. It was decided that this was not entirely correct in terms of the functionality of the built-in antennas. Attaching the device, for example, to a concrete wall, we completely closed the antenna.





On the front panel of the “transmitter” is a numeric green LED that shows numbers from 0 to 9 and helps determine the optimal location of the transmitter relative to the receiver. There is also a red indicator that signals a problem or an incorrect installation of the module, as described below, and a power indicator.







Below the cover device there is a power input and a reset button. Plus, the input micro-USB - apparently, for firmware and debugging.





Both devices are passively cooled. Heat is dissipated through numerous slots in the case. In these slots, probably, dust is perfectly collected.

Power adapters are the same, so do not confuse them.



Operating principle, technology

The windowing, receiving, module is installed in the zone of the most confident reception of the operator's signal - as a rule, on the windowsill. Since The case is half open, it will not be possible to install it outside due to unacceptable temperatures and humidity. But there should not be much difference for the signal. In addition, you can additionally connect an external antenna, but, as I understand it, this is for very neglected cases.



The received signal is transmitted to the device coverage via Wi-Fi. The blocks communicate with each other at a frequency of 5 GHz (the U-NII-1 frequency bands are 5.15-5.25 GHz or 5.25-5.35 GHz and U-NII-2 5.47-5.725 GHz). In this range, while there is no such garbage as in the usual Wi-Fi, but the arrival here of dual-band Wi-Fi can affect the situation. However, the processor algorithm contains a 7-microsecond cycle of checking the frequency freeness in this range, in the case of busy units “jump” to a clean one. if all bands are occupied, the blocks really cannot communicate with each other.

The distance between devices in a closed room can be up to 25 meters, depending on the possible signal loss during the passage of physical barriers (walls / partitions and their structural material). The experience of using people says that in areas where Wi-Fi does not penetrate, and this block does not work and vice versa. For example, a person writes that he placed the transmitter through three walls and about 7.5 meters from the receiver, and the modules did not see each other (there is also no Wi-Fi signal here). But placing it in the living room area, 10 meters, two walls, Wi-Fi coverage, we managed to achieve excellent work Cel-Fi.

The coverage device retransmits and amplifies the received 3G signal from the operator to an area of ​​up to 1,235 sq. M.

It is important that the signal is amplified in both directions - on the subscriber and on the base station.

Cel-Fi has an IntelliBoost Baseband processor installed. This is a specialized processor developed by Nextivity to optimize the reception and transmission of 3G-signal indoors. IntelliBoost has advanced filtering, signal equalization and echo cancellation. The processor is fast enough to provide high speed data transfer and a wide distribution of the 3G signal in the building. Cel-Fi allows you to simultaneously support up to 30 voice and 6 date sessions. IntelliBoost controls real-time gain by automatically adjusting parameters without adversely affecting the macro network. Cel-Fi RS2 supports the function of power control on the lines up and down, as well as automatic shutdown of the transmitter in the absence of subscriber equipment activity within the coverage area of ​​the subscriber terminal. Here, for clarity, measurements of the work of this function from one of the Russian operators:





The built-in Cel-Fi software is protected by a manufacturer code and is pre-configured to work with one of the authorized networks of cellular operators in Russia: MTS, MegaFon, VimpelCom, Rostelecom. You can create a firmware for any operator “on the lap”, but the protection will not allow you to fill the firmware into the device’s memory. You can reflash the device for another operator in the authorized center.

The Cel-Fi device does not require activation and registration of the IMSI-list of subscribers, as well as permits from the mobile operator. Cel-Fi RS2 has all the necessary permissions for installation and indoor use.

Specifications and features

• Processor: Nextivity's IntelliBoost Baseband II with the transfer of unmodulated signals, a high-tech algorithm for the suppression of echo signals and frequency-selective filtering.
• Cellular standard supported: UMTS 2100 MHz.
• Operating band: 5 GHz, in accordance with ETSI EN301 893 V1.5.1.
• Gain: up to 100 dB (up to 20 meters between the receiving device and the coating device).
• Maximum EIRP : downlink - (14.7 dBm on the downlink and up to 25.7 dBm on the uplink).
• Sensitivity WU: 104-106 dBm. If the signal is present at this value, then WU will receive-process-amplify and transmit the signal to the CU. For a weaker signal, you can install an external antenna. The antenna must be selected depending on the technical conditions: omnidirectional, directional: panel, parabolic.
• Working height: from -60 to 3050 m. I do not know what caused such restrictions, but the depth allows installing the device also in the subway or in mountainous areas, not higher and not lower than people usually live. The ability to use claims more than 99.9%. For extreme conditions, I believe, there are other, specialized solutions.
• Dimensions (width × depth × height): Reception device (Window Unit) 144 × 146 × 212 mm. Coating Unit 146 × 59 × 158.5 mm.
• Harm to health: complies with the WEEE 2002/96 / EC Health and Environmental Protection Regulations). The maximum power of the studied signal is 295 mW. This is less than the peak power of an ordinary mobile phone. Those. with a far greater distance from a person, there is no dangerous exposure at all.
• Power consumption: less than 12 watts per device.
• Operating temperature: 0-40 degrees, humidity 5-95% without condensation. This eliminates the installation of Cel-Fi on the street or even on the balcony.
• Recommended retail price - 19990 r.

The rest of the technical specifications, which are of interest mainly to specialists (compliance with standards, noise immunity, certification, etc.), can be found in the documentation for the device.

Algorithm Features

• the automatic gain control algorithm (AGC) continuously monitors signal loss from the base station and transmits power to ensure maximum gain.
• Uplink Gain Optimization to reduce noise at the base station input.
• automatic transmitter disconnection in the absence of subscriber equipment activity in the coverage area of ​​the subscriber terminal.
• the system is turned off by the operator’s network command or upon detection of a malfunction (the option is of higher priority for the operators).

Ability to use in:

• apartments
• offices
• cottages
• remote country cottage complexes
• business centers
• supermarkets
• storage, basement and parking areas
• industrial sites
• cafes and restaurants
• Other facilities with unstable and weak 3G (UMTS) signal level

Enable and configure

I plan to make a separate article with detailed testing of the device in different conditions, so I will describe now only a brief experience of the application.

I put the WU on the windowsill, where the phone shows 2-3 sticks.





According to the instructions, CU and WU must be distributed in such a way as to achieve the maximum numerical value on the CU screen.





It is quite inconvenient to carry the transmitter around the office because of the need to look for an outlet each time or to carry the extension cord. I would add a small backup battery, as they do in some electronic watches, so that you can turn off the power for a while and transfer it to another place without turning off the device. But in general, it is not critical.



I managed to find a place in the office where CU showed 8. The phones in the vicinity immediately gave out all the sticks of the 3G signal. Before inclusion in this place were floating 1-2 divisions.

Measurements made on the phone using Speedtest (download / upload / ping time):

• Cel-Fi off: 820/45/311
• Cel-Fi enabled, phone near CU: 2455/823/132
• Cel-Fi is on, the phone is about 7 meters from CU: 1617/729/61
• Wi-Fi for comparison: 19020/15934/8

Naturally, the quality of voice communication in this case also improves, echo disappears, delays, noise, interference.

In our office, I was not able to connect WU and CU even on 2 adjacent floors. Apparently, the problem is in the materials of interfloor floors. There was also a place where the 3G signal was weak even when running Cel-Fi. But in order to check how and what influences the signal level and draw conclusions, I am going to conduct detailed tests.At the same time, I’ll check a problem place known to me, where a phone without a repeater constantly jumps between 2G and 3G, periodically skipping incoming calls.

I have pictures with visualization of measurements for a 3-storey building.

3G standard coverage 3G



coverage with Nextivity Cel-Fi RS2 black



findings

To consider the Cel-Fi device in terms of "exactly help / not help" is not entirely correct. Of course, we must try.

However, even what I saw during a quick test is impressive. The 3G signal reaches its maximum, the data transfer rate increases markedly.

An important advantage can be saving battery power in the phone: Cel-Fi controls the power level between the operator’s base station and user devices in order to extend the battery life of subscriber devices.

There are also significant advantages of using Cel-Fi for mobile operators: increasing network capacity, increasing traffic, reducing the number of disconnections and, as a result, increasing user loyalty and reducing the load on technical support.

useful links

1. Description and documentation on the website of the official representative in Russia
2. Nextivity Coverage Tester ( Android)
3. MDMA (Mobile Data Monitoring Application)
4. Mobile Review (Cel-Fi RS2 white single band)
5. Nextivity

For reference, the company Nextivity was founded in 2006. Headquartered in San Diego (California). Nextivity Inc. He is a designer and developer of closed carrier-grade cellular systems, as well as their underlying software. The experience of the team includes participation in more than twenty start-up projects and cooperation with major companies such as Qualcomm, Broadcom, HP, Motorola and Intel. Headquarters in San Diego maintains sales and technical support offices worldwide through partners. Since July 2009, deliveries of Cel-Fi systems to operators in Europe, North America, Asia, the Middle East and Africa have amounted to tens of thousands of sets.

Chronology of the release and sales of products of the company Nextivity model Cel-Fi RS

Cel-Fi RS1 UMTS 2100 support (discontinued):



Cel-Fi RS2 white (single band) UMTS 2100 support (sales in Russia until the end of 2012):



Cel-Fi RS2 black (single band) UMTS 2100 support (sold in Russia since 2013):



Cel-Fi RS2 dual band UMTS 900/2100 support (sold in Russia since 2013):



Cel-Fi RS3 UMTS 900/2100, LTE support (expected in Russia in 2014):