Glitter and Poverty WiMax - An overview of the current market situation. Wireless technologies: Wi-Fi and WiMAX

- market in the country, the assessment of its current state can be reduced to the phrase "not very good yet, but the situation is getting better." No one had any doubts that this particular wireless communication standard will be the leading one during the next technological cycle. Unless, of course, you urgently need to implement some 5.5 G.

However, this was not always the case. In 2008, when in many regions of the country there were not even 3 G, claimed the role of "next generation wireless communication" WiMax. At that distant time, the standard was the only one capable of providing a mobile access speed of several megabits and implemented in hardware. It should be noted that then the situation with high-speed Internet (and with the Internet in general) was rather sad. At the same time, it was sad not only in the cellular segment, but also in the wired one. There was not even a trace of 50 megabits / s for 600 rubles, for this money you could buy much less. Against this background, proposals from Yota (Skartel LLC) seemed incredible: speeds up to 10 Mbit / s, no traffic threshold, a monthly fee of less than a thousand rubles, the ability to use anywhere in the coverage, no roaming ...

After an excellent start of Iota, the operators of the second echelon reached out: Comstar, Freshtel, Soyuz-Telecom, WiTe. Everyone tried to join WiMax and snatch the subscriber base from cell phones. When the “locomotive” represented by Yota announced its own phone"Yota Cosmos" with unlimited calls within the network and an affordable price, mobile operators are completely sick. It is not surprising - they make a significant part of the proceeds in the capital markets, as the most capacious and solvent ones. Losing them meant getting on a par with Tele 2.

However, Yota plans was not destined to come true. After a while, it was announced that the project for the introduction of native voice communication was stopped. The official reason was the inability to provide acceptable quality, which contains a certain amount of guile - voice requires noticeably less bandwidth than data. Be that as it may, the project was curtailed, and he failed to revive. Around the same time, the triumphal procession WiMax -operators lost their pace, and the previously cheerful players lost their wings and descended to the sinful land.

Why didn't it work Yota and almost everyone else?

There are several reasons for the failure of the standard in general (and Scartela in particular).

First, the company was too diffuse. Instead of focusing exclusively on the Russian market, she decided to go international and started building networks in Nicaragua and Belarus. After a short time I had to leave there. The same goes for the phone. Cosmos and "the first network in Russia LTE "- all the developments were simply thrown out. Net LTE in Kazan it was generally empty, since Scartel did not have the appropriate licenses. One of the results of this policy was the underfunding and delay in the construction / modernization of networks in Russia.

Secondly, an inflexible pricing policy. At the time of launch, only two tariffs were offered: daily (50, and then 90 rubles) and monthly (900 rubles per month). The speed on the tariffs was maximum, so those who needed an inexpensive, not too fast, but stable Internet were not covered by the offer.

Third, the company's networks were heavily overloaded. This was a consequence of the pricing policy, which did not imply any restrictions on traffic or speed. As a result, subscribers rushed to download torrents and watch videos, which "put" a significant number of base stations. Rumors of "a disgustingly working Internet" immediately spread across the network.

Finally, fourthly, the strange coverage policy. The network's subscribers were residents of high-rise buildings in the largest cities. Although, as we mentioned above, wired Internet was not very developed then, providers did not stand still. The speed grew, the price fell, they bought Wi-Fi -routers. As a result, Scartel ceased to be an “operator for everyone” and was ousted from apartments as the main channel. The private sector and cities in the regions (Moscow and Leningrad), marketers diligently did not notice, guided by the saying "There is no life behind the ring road". But it is there that access to the network is much more needed than in the capitals, because in those days, even in high-rise buildings, everything was very bad. Residents of the regions would gladly use Iota as a stationary channel, even with a strong speed limit (2 or even 1 Mbit / s), because at the end of 2013, the Internet in the private sector is not all right.

The rest of the providers have slightly different reasons for closing. For example, Comstar through MGTS was bought by MTS and closed so as not to create competition for the technology LTE. Other operators simply did not have enough money to achieve at least an operational payback. Some did not go further, confining themselves to a couple of cities, since they did not see themselves as a competitor to the “big three”. In general, the reasons were different, but the result was the same - the curtailment or freezing of almost all projects.

We decided to review the proposals WiMax in the country, at the same time seeing how the operators are currently feeling.

Yota

We talked a lot about it in the previous paragraph. To what has been said, it should be added that nothing remained, not only of the original plans, but also of the company itself: its Megaphone. In general, the company fully justified its logo in the form of a man standing upside down.

The official site is still active and offers to connect, but this is unlikely to last long. The pricing policy of Skartel and Megafon is fundamentally different.

Comstar

Another operator that fell under the onslaught of competitors from the world of cellular communications. In 2011, MTS merged COMSTAR-United TeleSystems, and at the end of summer 2012, the network WiMax was finally closed. All clients were redirected to the network LTE:

Unlike the Yota site, where there was no mention of the technology, on the Comstar site everything was preserved in its original form (without the functions of connecting and buying, of course) and you can see "how it was". For example, here are the tariffs:

The operator introduced tariffs with traffic limitation, but with reasonable prices for cost overruns. Apparently, Iota's experience pushed to such a decision.

Soyuz Telecom

The first active operator in our review, although it can only be called an active operator at a stretch. The most recent news is dated 2011, there is no coverage map, and user reviews are extremely negative. Subscribers complain about regularly missing services, irresponsible technical support, lack of any information and long time for equipment repair:

However, not only subscribers have problems, but also official dealers, who also do not know what to do:

At the moment, the discussion of the provider is practicallystopped(all active users switched one way or another). There were rumors about the sale of equipment and the transfer of clients to new operators, but there is no official information on this matter.

The supervisory authority has repeatedly brought the operator to responsibility for failure to comply with license conditions and work without the necessary documents. For example, in March 2012, an unscheduledexaminationRoskomnadzor Administration for the Altai Republic, as a result of which several protocols of administrative violation were issued. The company had problems with the commissioning of SORM, work without registration of RES and permits for radio frequencies. In November 2012, residents of the town of Chusovo, Perm Krai, complained about the lack of the service. Complaintrecognizedlegal, fined the operator 30 thousand rubles and sent the initiated administrative case to the Moscow Arbitration Court. In addition to the cases described, there were several more violations for which the operator was issued fines and warnings.

What is the provider's problem? In our opinion, it consisted in an attempt to cover everything at once. The company received a huge number (47 pieces) of licenses that needed to be implemented:

At the same time, they were required to be implemented almost throughout the country. Soyuz-Telecom proudly declared that “The company has 47 licenses for the provision of 5 communication services in 80 regions of Russia, including "Communication services for data transmission for the purpose of transmitting voice information", "Communication services for data transmission, excluding data transmission services for the purpose of voice information transmission" , "Telematic communication services", "Communication services for the provision of communication channels" and "Local telephone communication services, excluding local telephone communication services using payphones and public access facilities." Of course, these plans were not destined to come true without millions of dollars of investment. Most likely, the company's strategy was to quickly recruit the minimum number of customers that would pay off the current activities. The calculation did not come true, the cash flow turned out to be less than required and the operator began to sink. In general, another example of the fact that you need to bite off as much as you can chew.

There was only one tariff, but with the ability to pay for several months and get a discount:

WiTe

Another operator with Napoleonic plans, which were not destined to come true. In 2009, it was promised to launch networks in 25 cities of six federal districts within two years. However, the plans were not destined to come true, and as a result, the network started working in only two cities: Kemerovo and Topki. Most likely, the company simply did not have enough money - the $ 25 million that was planned to be allocated to cover the regions was too small a sum. Despite the losing strategy "all at once", the company escaped the fate of Soyuz-Telecom. Having managed not to get involved in the race to increase its presence, the provider concentrated in one place and managed to survive to this day.

Although work is announced in two cities, the coverage map is shown for only one:

But with the tariffs, the company is all right. The operator did not chase the unification and minimalism that no one needed, but presented a whole line:

The line includes tariffs with or without traffic limitation. In addition, daily rates are available: WHITE DAY for 50 rubles and WHITE EXPRESS for 75 rubles. Everyone is given 2 days to test the network. If the result is not pleasing, the failed subscriber can return the funds paid in advance by returning the equipment.

For the city of Topki, the tariffs are much lower:

The specificity of the tariffs are the terms of use. The fact is that tariffs are tied to the type of equipment, and the name of the equipment is misleading. For example, the "White Fix" tariff is available for the equipment named "Modem", although it is understood as USB- modem and router. But the equipment called "Router" means an external antenna and a high-performance router. The point is most likely that "routers" have a much more sensitive antenna. Since with a large antenna the signal becomes more stable and the access speed increases, tariffs had to be adjusted in the direction of decreasing the traffic threshold or increasing the subscription fee. Otherwise, stationary subscribers will create a heavy load on the base station.

The devices are offered one model per type: modem, router (mobile and stationary), stationary station and external antenna:

Device	price, rub.
Seowon SWU-3220A USB Modem
WiFi router Seowon SWU-8200
Router Seowon SWC-3200
Greenpacket OX 350
External antenna for routers

A set of devices for working in a WiTe network

Reviews about the provider are different. More often, of course, they scold, but in itself this is not an indicator - people scold people much more readily than they praise. People complain about low speed, unstable connection, unavailable technical support. Some of the complaints are really justified - the speed of less than 1 Mbit / s can be considered a problem, but there are also complaints like “I can't watch movies online”. Unfortunately, not all people understand that watching movies online wirelessly without any restrictions is currently possible only with a lot of luck.

FRESHTEL

The only provider that provides services in several cities and somehow develops, and is not on the verge of bankruptcy. The network covers several dozen cities in 12 regions of the country, with most of them located in the Central Federal District. Apparently, the company closely followed the development (more precisely, how they fold) of competitors and learned from their mistakes. Therefore, Freshtel is not only developing nearby regions, but also does not try to compete with providers of wired access in high-rise buildings, concentrating on the private sector. For example, this is how the coverage area in the city of Shakhty looks like:

If you enlarge the map, it will be seen that mainly the services will be provided to residents of the private sector. There are also apartment buildings in the zone, but they are low-rise, so wireless Internet services will also be in demand there. The operator is developing not only small towns, but also regional centers. For example, there is also a network in Samara. Alas, not in all areas:

The full list of presence includes 37 cities:

Some of the cities were launched quite a long time ago, and some quite recently. The last cities, Samara and Togliatti, were connected in the autumn of the outgoing year.

The operator has two tariffs: with a traffic limit of 20 (10) GB and unlimited. They are the same for almost all cities. The first costs 590 rubles, the second - 790 rubles per month. The speed is up to 10 Mbit / s maximum in theory (in practice, everything is much more modest). For a tariff with a traffic limit, after its exhaustion, the speed is limited to 256 kbps. Modestly, but still much better than 64 kbps handouts from cellular operators:

There are a lot of devices: two types of modems, five types of routers, an external unit and four external antennas. The price of modems is higher than the rest: 1890 rubles for the ZTE AX320 USB Dongle and 1990 rubles for the Seowon SWU-3220A USB Dongle. Fortunately, since 11/07/2013 the action "Internet in your pocket for 99 rubles" is taking place, within which modems can be purchased for only 99 rubles. The promotion will continue until the last modems of this type are sold. Promotions are also valid for other devices, but with a time limit:

Separately, it is worth noting the possibility of payment for services. There are several ways to choose from: through terminals, bank cards, electronic money and even Sberbank of Russia:

Such a large number of payment methods suggests that the company understands that it is necessary to fight for the client, and not to force him to personally appear at the office in order to give the company his money.

There are a lot of reviews about the operator and the overwhelming majority of them are negative. A significant part of them is that "they promised 10 Mbit / s, but in reality it is much less." Then the operator for some reason decided not to take into account the experience of Iota and walked along the rake at speeds "up to 10 Mbps." It is clear that the subscriber will be able to see 10 Mbit / s only under the base station, being its only client. Alas, in the pursuit of connections, marketers write numbers in tariffs that are extremely far from reality. Lots of complaints about cut torrents, but here we can understand the provider. Torrents will download any communication channel 100%, wireless connection will not physically pull them. So for the convenience of other users, torrents should be limited. Claims here can be made for not informing subscribers, some of whom are connected precisely for the sake of downloading movies and games from trackers. There are also completely unfounded claims:

I wonder which wireless service provider provides a constant speed of 1 Mbps?

In general, subscribers are indignant and threaten to switch to cellular operators. Their speed is really higher, as well as stability, but for some reason everyone forgets that traffic is strictly limited and after the monthly volume is exhausted, the speed drops to 64Kbps.

In the summer we went on the takeover of Freshtel by TransTelecom, but they never found confirmation.

Was there a chance?

Having considered the largest federal operators WiMax, we can say that the standard in Russia is rather dead than alive. Cellular players switched to LTE, small locals prefer different variations Wi-Fi. For WiMax there is still not a very large niche of corporate clients who cannot connect to wires for various reasons, but which cannot be connected by Wi-Fi is not possible.

Looking into the past from today's perspective, let us ask ourselves: did you have a chance WiMax? We think so. Small but real. The standard was lucky twice: the first time when a crisis came and mobile operators froze large construction projects. A crisis is not good for most, but not for someone who has money. The cost of equipment, wages, logistics costs - everything is cheaper during a crisis. In addition, contractors have less work to do, which means they can build faster. The second time the standard was lucky when it turned out that 3 full-fledged networks G it is impossible to deploy in some places, and LTE will be launched at all unknown when. At the time of the start of implementation WiMax technologically superior to the then available third-generation networks several times.

Thinking about what needed to be doneknowing the buyoutlooking at all the successful and unsuccessful steps from the standpoint of history is not very correct, but we will try everything. So for development WiMax As a standard, the following steps were required:

Do not scatter efforts across the country, but focus on nearby regions and cities. What's the use of roaming without extra charge between Moscow and Ufa, if the flow of people between them is minimal? But roaming between Moscow and Dolgoprudny would be much more in demand.

Make carpet in capitals first ... Moscow and the corresponding regions are a cash cow for operators. A significant part of the country's population lives here, which is solvent. Belarus is, of course, good, but financially incomparable with Moscow or St. Petersburg.

Collaborate with local players ... One of the obstacles to the development of any wireless technology is the need for infrastructure to the base station. If you intend to make a sufficiently dense coverage, you cannot do without optical networks from the point of attachment. Line construction takes time and money. You can buy a channel from local players, but then they will not be interested in developing the network. But an agency scheme or a full-fledged partnership could have a synergistic effect: the locals would get the opportunity to connect the private sector, and wireless - the necessary network resources and an interest in success. Most importantly, time would be gained and the networks could be deployed much faster.

Combining efforts ... You can learn something together much faster than separately. If all providers WiMax divided the zones of influence, but acted under a single brand (such a model was used by cellular companies at the beginning of the journey), things went much faster. Unfortunately, this scenario is even more fantastic than the previous one.

Greater variety of tariffs ... We have already touched on this topic. The poor tariff line, which does not allow the subscriber to find exactly "his" tariff, pushed a certain number of customers away from the standard. Not everyone needed speeds "up to 10 Mbps" for 900 rubles, someone wanted to spend 300 and be able to use mail, read news and listen to the radio slowly and without restrictions.

The soonest introduction of unlimited voice and the release of inexpensive phones ... Even if the networks WiMax offered a single service in the form of unlimited calls and SMS for a small amount, a lot of people would have connected to them. The experience of Tele2 shows that cheap voice communication is in high demand. Basic services in the form of voice load the station quite a bit (these are not torrents or even web pages), and the price tag of 300 rubles makes such a connection available to the general population.

If these conditions were met, the situation with WiMax would be completely different. Who knows, maybe now we would Discussed not the introduction of LTE, but WiMax-2.

WiMAX is a telecommunications technology designed to provide wireless, universal communication over significant distances for various devices, from workstations and laptop computers to mobile phones. The technology is based on the IEEE 802.16 standard, also called Wireless MAN (in general, WiMAX is a slang name, since it is not a technology, but a forum where Wireless MAN was agreed upon).

The name "WiMAX" was created by the WiMAX Forum, founded in June 2001 to promote and develop WiMAX technology. The designated forum describes WiMAX as "a standard-based technology that provides wireless high-speed network access, an alternative to DSL and leased lines." The maximum speed is 1 Gbps per 1 cell.

Scope of application

WiMAX is suitable for solving the following tasks:

• Connection of Wi-Fi access points between themselves and with other segments of the Internet.
• Provide broadband wireless access as an alternative to DSL and leased lines.
• Provision of high-speed information transfer and telecommunication services.
• Creation of access points not tied to geography.
• Creation of remote monitoring systems, as in the SCADA system.

WiMAX enables high speed Internet access with much greater coverage than Wi-Fi networks. This allows the technology to be used as "trunk channels", the continuation of which are leased lines and DSL, as well as local networks. This approach ultimately allows you to create high-speed scalable networks within cities.

Feasibility of using WiMAX as an access technology

The last mile has always been a pressing problem for communications. Now there are many technologies of the last mile, any telecom operator faces the task of choosing a technology that will optimally deliver any type of traffic to subscribers. There is no universal solution to this problem, each technology has its own field of application, its own advantages and disadvantages. The choice of a specific technological solution is determined by a number of factors, in particular:

• target audience, operator strategy, services currently offered and planned;
• the amount of investments in the development of the network, the payback period of these investments,
• the already existing network infrastructure, the resources necessary to maintain it in an efficient state,
• the time it takes to launch the network and to start providing services.

Each of these factors has its own weight, the choice of a certain technology is made taking into account all of them in a complex.

Fixed and mobile WiMAX options

The entire WiMAX family has a number of advantages, but different versions of it differ significantly. The developers of the standard were looking for the best solutions for both fixed and mobile use, but they failed to combine all the requirements within a single standard. Although some basic requirements are the same, the focus of technologies on different market niches has led to the creation of 2 separate versions of the standard (more precisely, they can be considered 2 different standards).

Each WiMAX specification defines its own operating frequency ranges, radiation power, bandwidth, transmission and access methods, signal coding, signal modulation, principles of radio frequency reuse and other indicators. Therefore, WiMAX systems that are based on the IEEE 802.16 standard, namely versions e and d, are almost incompatible.

The characteristics of each version are as follows:

• 802.16-2004 (also known as 802.16d). Approved 2004. Orthogonal frequency division multiplexing (OFDM) is applied, and fixed access is supported in areas with or no line-of-sight. The user device is a fixed indoor / outdoor modem and PCMCIA cards for notebook computers. In most of the countries, the 5 GHz and 3.5 GHz bands have been allocated for the aforementioned technology. According to the WiMAX Forum, there are already 175 fixed version deployments. Many analysts see it as a competing or complementary technology for broadband wired DSL access.
• 802.16-2005 (aka 802.16e, mobile WiMAX). Approved in 2005. It is a new round of development of fixed access technology. The version is optimized for mobile users and supports a set of specific functions - roaming, handover and idle mode. Scalable OFDM access (SOFDMA) is used, it can work with or without line of sight. The planned frequency ranges for Mobile WiMAX networks are 2.3-2.5, 2.5-2.7 and 3.4-3.8 GHz. Today, several pilot projects have been implemented in the world, and the first in Russia has deployed its network "Scartel". A project called FlyNet (flynet.kz) was implemented in Kazakhstan. 802.16e competitors are all 3rd generation mobile technologies (eg EV-DO and HSDPA).

The main difference between the two technologies is that fixed WiMAX serves only "static" subscribers, while WiMAX mobile works with users traveling at a maximum speed of 150 km / h. Mobility implies the presence of roaming, as well as "seamless" switching between base stations during the movement of the subscriber (similar to cellular networks). In special cases, mobile WiMAX can be used for servicing fixed users.

Broadband access

Many telecommunications companies are betting heavily on the use of WiMAX for high-speed services. There are reasons for this.

First, 802.16 technologies make it possible to more efficiently (in relation to wired technologies) not only provide new customers with access to the network, but also expand the range of services and cover new territories.

Second, in many ways, wireless technologies are easier to use than traditional wired links. WiMAX networks are easy to deploy and scale easily as needed. This factor turns out to be useful when you need to deploy a large network in a short time. Thus, WiMAX was used to access the Network of the surviving part of the victims of the tsunami that happened in December 2004 in Indonesia. The entire communication infrastructure of the affected region was out of order and it was necessary to promptly restore communication services throughout this region.

In sum, all these advantages allow to reduce the prices for high-speed Internet access services for both enterprises and individuals.

User equipment

Equipment for WiMAX use is supplied by several manufacturers, it can be installed both indoors (devices having the size of a conventional DSL modem) and outdoors. Equipment that is designed to be placed indoors and does not require installation skills is, of course, more convenient, but it can work at much shorter distances from the base station than external professionally installed devices. Therefore, the equipment that is installed indoors requires a much larger investment in network infrastructure, since it implies the use of a much larger number of access points.

With the advent of mobile WiMAX, more and more emphasis is placed on the development of mobile devices - special handsets (similar to a regular mobile smartphone) and computer peripherals (in particular, USB radio modules, as well as a PC card).

Basic concepts

WiMAX networks generally consist of the following basic parts: base stations and subscriber stations, and equipment that connects base stations with each other, as well as with the Internet and with a service provider.

To connect the subscriber station to the base station, a high-frequency range of radio waves of 1.5-11 GHz is used. The information exchange rate can in ideal conditions reach 70 Mbps, providing a line of sight between the receiver and the base station is not required.

WiMAX is used to solve the problem of the "last mile" and access to the network of district networks and office networks.

Between base stations, connections are established (line of sight) using the frequency range 10-66 GHz, while the highest information exchange rate is 140 Mbit / s. At the same time, at least one base station is connected to the provider's network using a classic wired connection. But the more BSs are connected to provider networks, the faster data is transmitted and the higher the overall reliability of the network.

The structure of IEEE 802.16 networks is similar to that of traditional GSM networks (base stations operate at distances of up to tens of kilometers, their installation does not require the construction of towers - they can be installed on the roofs of houses, observing the conditions of line of sight between these stations).

MAC / link layer

In Wi-Fi networks, all user stations seeking to transmit data through a specific access point (AP) compete for its "attention". This approach may lead to a situation in which for more distant stations the connection will be cut off constantly in favor of stations that are closer. This situation makes it difficult to use Voice over IP (VoIP) services, which are highly dependent on uninterrupted connections.

With regards to 802.16 networks, MAC uses a scheduling algorithm. Each user station has only to connect to the access point, and a dedicated slot will be created for it on the access point, which is not available to other users.

If you don't know what WiMAX is and how it works, then you really have lost a lot.

It is a very high quality communication technology (stands for) that provides wireless communication.

Content:

You may have heard of such concepts as GSM, UMTS and so on.

So, here we are talking about the same technology that is actively used in a variety of devices and systems. It can be seen in workstations, PCs and mobile phones.

At the same time, it is quite fast and mobile, but an ideal balance has been found between these two characteristics. Figure 1 illustrates this in the graph.

In other words, WMAX provides both information transfer and telephony services.

There are other solutions to this problem in the world, but this technology is the simplest and most convenient of them.

And now we will be in more detail review the various features and operating principles of the Wireless MAX.

A brief history of the development of communication technologies

To better understand how WMAX works, you need to understand how it came about. So here's to you a small excursion into history:

AMPS comes first, a standard that allows you to communicate with other callers using a simple receiver. This is the first generation. The techniques used in it have long been abandoned.

Then GSM appears which we all use to make mobile phone calls. Also, at the same time, CDMA appears, which has already made it possible to receive Internet services. This is the second generation.

Combination of GSM and CDMA allowed to create GPRS, and then and. Surely, many of us remember how in the mid-2000s we began to go to various sites from our cellular devices. It was a real sensation then, but the pages were highly compressed and adapted for such phones. Over time, we began to see pages as they appear on computers. This is due to the fact that heavily revised versions of GPRS and CDMA have appeared - HSUPA, CDMA 2000 1x and later CDMA EVDO.

So, Wireless MAX can be attributed to the third generation. Together with it, LTE appears.

As for the history of the technology we are considering itself, there everything developed as follows:

• In 2004, the very first version appears. Its main feature was that the signal was transmitted over distances of up to 50 km. But the transmitting and receiving devices themselves were rather cumbersome and inconvenient. It was very difficult to move them.
• MobileWiMAX appears in 2005, which is used to this day. The word "Mobile" in the name indicates not that this concept is used in mobile phones, but that the technology itself has become more mobile. This means that transmitting and receiving devices are more mobile - easier to move and manage.
• Over time, developers come up with preWiMAX which operates at frequencies of 6 GHz or so. MobileWiMAX operates at 2-5 GHz. At the same time, in preWiMAX, any interference, for example, buildings, is unacceptable between the transmitting and receiving devices. They must be visible to each other.

For comparison: GSM networks operate at 0.8-1.9 GHz and CDMA at 0.45 GHz. Therefore, they are somewhat more mobile - devices do not need to be in line of sight.

Nevertheless, Wireless MAX gained immense popularity and is used very actively today. This is due to the purpose and characteristics.

Difference with Wi-Fi and 3G

Important! ComparisonWiMAX with3 G or evenWi- Fi is completely incorrect. They are designed for different needs and belong to different branches of technical activity. You can compare them only in terms of speed, bandwidth and some other characteristics. But they are still not used in the same places.

To be more specific, then Wireless MAX is only used on citywide wireless networks called WMAN.

An approximate visual representation of such networks can be seen in Figure 2.

As you can see, the Internet signal does not get from one device to another, but. Other buildings receive its signal thanks to appropriate devices.

In principle, the picture is the same as in Wi-Fi, but the tasks performed in Wimax are completely different. This technology enables the transmission of huge data streams in cities.

Wi-Fi, on the other hand, transmits information over short distances.

The same goes for 3G. This technology also has large transmitters, but the signal from them goes to smartphones, tablets and other devices with SIM cards that can pick up such a signal. But in Worldwide Interoperability for Microwave Access Internet is caught by special receivers.

Learn more about where it is used

So, the technology under consideration is used to transmit the Internet signal throughout the city. That is, you can transmit such a signal to a building that is at a great distance.

More specifically, Wimax suitable for such tasks:

1 Alternative to leased lines as well as DSL. These are usually wired technologies, which in most cases are used to provide telephone communications. So, Wireless MAX can replace them, and without using wires.

2 Data transfer and Internet sharing. This refers to the standard user access to the worldwide network for work, study, watching videos, being on social networks, and so on. Although Wimax has too many resources for such tasks.

3 Connection of access points, as well as the creation of such. In this case, the access points will not be tied to a physical location (like a router). In terms of connectivity, you can take, for example, multiple Wi-Fi devices and connect them to different network segments or to each other. This is useful when their range is not sufficient for communication.

4 Monitoring systems, within the framework of which there is monitoring of any parameters of the networks and their control. Large firms always have such systems.

But in general, Worldwide Interoperability for Microwave Access Is an extremely high-speed and versatile technology, so it is not surprising that more and more people are using it now.

Key features of the Wireless MAX

Here list of features of this technology:

• several antennas are used to receive and transmit a signal;
• to convert a digital signal to analog, the Fourier formula is applied(the better the signal, the more);
• thanks to TDD there is no need to perform an unnecessary operation in the form of a choice of frequency for receiving and transmitting;
• at the moment work regulated by the IEEE 802.16 standard;
• thanks to some technologies, it is possible to work even in densely built-up areas;
• the cost of equipment is higher than with Wi-Fi, and even more so 3G.

Of course, this is far from all that could be said, but even from this it is clear that WMAX has a huge number of advantages over other communication technologies.

The IEEE 802.16-2004 standard considered in the article is an extension of the basic IEEE 802.16 standard, which describes operation in the 10… 66 GHz range. The IEEE 802.16-2004 standard provides for operation in the 2 ... 11 GHz range, as well as broader capabilities both at the physical layer and at the access control level.

Introduction

WiMAX (Worldwide Interoperability for Microwave Access) refers to a carrier-grade technology that is based on the IEEE 802.16 family of standards, developed by the International Institute of Electrical and Electronic Engineers (IEEE). The IEEE 802.16 standards define the physical and access control layers for metropolitan fixed wireless broadband access systems.

The main parameters of the IEEE 802.16 and IEEE 802.16-2004 standards are presented in table. one .

Table 1. Basic parameters of IEEE 802.16 and IEEE 802.16-2004 standards

Description of the standard

At the physical layer, the IEEE 802.16-2004 standard defines three data transmission methods: single carrier modulation (SC), orthogonal frequency division multiplexing (OFDM), and OFDMA.

The WirelessMAN-OFDM physical layer specification is the most interesting from the point of view of practical implementation. It is based on OFDM technology, which significantly expands the capabilities of the equipment, in particular, it allows you to operate at relatively high frequencies in the absence of line of sight. In addition, it includes support for an “one-to-one” topology (mesh), in which subscriber devices can simultaneously function as base stations, which greatly simplifies network deployment and helps to overcome line-of-sight problems.

OFDM modulation

When generating the OFDM signal, the digital data stream is divided into several substreams, and each subcarrier is associated with its own data substream. The amplitude and phase of the subcarrier are calculated based on the selected modulation scheme. According to the standard, individual subcarriers can be modulated using Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), or Quadrature Amplitude Shift Keying (QAM) of the order of 16 or 64. Bit to phase plane mapping options for each type of keying are shown in Fig. 1. At the transmitter, the amplitude as a function of phase is converted to a function of time using the inverse fast Fourier transform (IFFT). The receiver uses Fast Fourier Transform (FFT) to convert the signal amplitude as a function of time to a function of frequency.

Rice. 1. Options for displaying bits on the phase plane

The use of Fourier transform allows you to divide the frequency range into subcarriers, the spectra of which overlap, but remain orthogonal. The orthogonality of the subcarriers means that each of them contains an integer number of wobbles per symbol period. As seen from Fig. 2, the spectral trace of any of the subcarriers has a zero value for the "center" frequency of the adjacent trace. It is this feature of the subcarrier spectrum that ensures the absence of interference between them.

Rice. 2. Orthogonal subcarriers

One of the main advantages of OFDM is its robustness to multipath effects. The effect is caused by the fact that the emitted signal, reflected from obstacles, arrives at the receiving antenna in different ways (Fig. 3), causing intersymbol distortion. This type of interference is typical for cities with multi-storey buildings due to multiple reflections of the radio signal from buildings and other structures. To avoid intersymbol distortion, a guard interval called a cyclic prefix is ​​inserted in front of each OFDM symbol. The cyclic prefix is ​​a fragment of the useful signal, which ensures that the orthogonality of the subcarriers is preserved (but only if the reflected signal in multipath propagation is delayed by no more than the duration of the cyclic prefix). In addition, the cyclic prefix allows you to select the window for the Fourier transform anywhere in the symbol's time interval (Fig. 4).

Rice. 3. Illustration of the effect of multipath propagation

Rice. 4. Multipath OFDM symbol processing

Anti-interference coding

Multipath propagation of a radio signal can lead to attenuation or even complete suppression of some subcarriers due to interference of the direct and delayed signals. To solve this problem, error-correcting coding is used. In the IEEE 802.16-2004 standard, both traditional technologies of error-correcting coding and relatively new methods are provided. The traditional ones are convolutional coding with Viterbi decoding and Reed-Solomon codes. The relatively new ones are block and convolutional turbo codes. Data interleaving is used to increase the coding efficiency without reducing the code rate. Interleaving improves coding efficiency because error packets are broken up into smaller chunks that the coding system can handle.

Flexibility

An important feature of the physical layer is the ability to select the bandwidth for the channel bandwidth. The standard allows for bandwidth selection in steps of 1.25 MHz to 20 MHz with many options in between to make more efficient use of the RF spectrum. In addition, the standard includes an adaptive signal-code structure, that is, the system adjusts to the channel characteristics at each moment of time, "pumping" the speed into noise immunity and vice versa. In accordance with the standard, depending on the signal-to-noise ratio (S / N), the system chooses a modulation method that can provide stable operation (Fig. 5).

Rice. 5. Preferred modulation method depending on signal-to-noise ratio

Additional physical layer tools to improve the efficiency of radio spectrum utilization are channel quality measurement and automatic signal power control.

Access method

The IEEE 802.16-2004 standard uses time division multiple access (TDMA) technology, according to which the base station allocates time slots to subscriber stations so that they can transmit data in a specific order, rather than randomly.

Two technologies are used to implement full duplex communication: downstream and upstream time division duplex (TDD) and frequency division duplex (FDD).

Data protection

In accordance with the standard, all traffic transmitted over the network is encrypted to prevent unauthorized access and protect user data. The base station (BS) WiMAX is a modular construct in which, if necessary, you can install several modules with their own types of interfaces, but the administrative software for network management must be supported. This software provides centralized management of the entire network. The logical addition of subscriber sets to the existing network is also carried out through this administrative function.

A subscriber station (SS) is a device that has a unique serial number, MAC address, and a digital signature X.509, on the basis of which the SS is authenticated at the BS. Moreover, according to the standard, the validity period of the digital signature of the AU is 10 years. After installing the speaker at the client and turning on the power, the speaker is authorized at the base station using a certain frequency of the radio signal, after which the base station, based on the above identification data, transmits the configuration file to the subscriber using the TFTP protocol. This configuration file contains information about the sub-band of data transmission (reception), the type of traffic and the available bandwidth, the schedule for the distribution of keys for traffic encryption and other information necessary for the operation of the AS. The required file with configuration data is created automatically after the administrator of the AC system enters the subscriber base, with the assignment of certain access parameters to the latter.

After the configuration procedure, the AU authentication at the base station is as follows:

• The subscriber station sends an authorization request, which contains the X.509 certificate, a description of the supported encryption methods and additional information.
• The base station, in response to an authorization request (if the request is valid), sends a response containing an authentication key encrypted with the subscriber's public key, a 4-bit key to determine the sequence required to determine the next authorization key, and the key lifetime ...
• During the operation of the AS, after a period of time determined by the system administrator, repeated authorization and authentication takes place, and in case of successful passing of authentication and authorization, the data flow is not interrupted.

The standard uses the PKM (Privacy Key Management) protocol, according to which several types of keys are defined for encrypting the transmitted information:

• Authorization Key (AK) - the key used to authorize the AK at the base station;
• Traffi c Encryption Key (TEK) - a key used to encrypt traffic;
• Key Encryption Key (KEK) is a key used to encrypt the keys transmitted over the air.
• According to the standard, two keys are used simultaneously at each moment of time, with overlapping lifetimes. This measure is necessary in an environment with packet loss (and in the air they are inevitable) and ensures the continuity of the network. There are a large number of dynamically changing keys, which are quite long, and secure connections are established using a digital signature. According to the standard, encryption is performed in accordance with the 3-DES algorithm, and encryption cannot be disabled. Encryption is optionally provided using the more reliable AES algorithm.

Development of WiMAX equipment based on "systems on a chip"

Modern trends in the development of the telecommunications market dictate the development of so-called "systems on a chip". System-on-a-chip devices are generally understood to mean devices on a single chip of which one or more processors, a certain amount of memory, a number of peripheral devices and interfaces are integrated - that is, the maximum that is necessary to solve the tasks set for the system. The development of "systems on a chip" involves the optimization of the developed circuitry, which directly affects the power consumption, chip area and, as a consequence, cost.

Currently, the world's leading manufacturers have focused on the development of "systems on a chip", which integrate the main functions of the physical and MAC layers of the WiMAX standard. The first samples developed based on the IEEE 802.16-2004 specification were presented by Fijitsu, Intel, Sequans Communications, Wavesat and PicoChip. The solutions proposed by these companies use OFDM modulation with 256 subcarriers at the physical layer and a basic coding scheme in which convolutional coding and Viterbi decoding are used for the inner code, and Reed-Solomon codes for the outer one.

Functionally, WiMAX equipment is divided into basic and subscriber equipment. The first generation of chips for base stations has a lower level of integration than for subscriber stations. To implement the base station MAC protocol, an increase in the performance of these solutions is required. For this purpose, external processors are used to execute the upper layer of the MAC protocol. Thus, WiMAX chipsets implement the physical layer functions and the lower layer functions of the MAC protocol.

Subscriber equipment

For developers of WiMAX subscriber equipment, the most promising are "systems on a chip" from four manufacturers: Fujitsu, Intel, Sequans and Wavesat.

Intel was the first to offer developers a PRO / Wireless 5116 "system-on-a-chip" for WiMAX subscriber stations, in which the functions of both physical and MAC layers were integrated. The MB87M3400 chip from Fujitsu is designed for a wider range of applications and allows you to develop both basic and consumer equipment. Sequans has developed separate SQN1010 and SQN2010 chips for base and subscriber equipment, respectively.

Systems on a chip from Fujitsu, Intel and Sequans fully implement MAC functionality for WiMAX subscriber stations. Another approach to development was proposed by Wavesat, releasing two microcircuits: the DM256 OFDM modem (which implements the functions of the physical layer) and the MC336 (which is a computing core that implements the lower layer of the MAC protocol). Fujitsu, Intel, and Sequans do not need an additional external processor to develop a system-on-a-chip subscriber modem from Fujitsu, Intel and Sequans.

The characteristics of the considered chips, determined by the type of duplex, channel width, and other parameters, are very different. The Fujitsu MB87M3400 solution requires two chips for full duplex operation. The Sequans SQN1010 is the first system-on-a-chip to support full duplex operation. Wavesat's DM256 / MC336 solution also enables full-duplex operation based on a single DM256 OFDM modem chip.

Microcircuits from Fujitsu and Sequans allow organizing channels with a width of up to 20 and 28 MHz, respectively, while the maximum channel width for Intel and Wavesat chips is 10 MHz with intermediate values ​​of 3.5 and 7 MHz.

The radio interface of the considered "systems on a chip" contains ADC / DAC units for direct analog connection with an external transceiver. Table 2 presents the main parameters of solutions for the development of WiMAX subscriber equipment.

Table 2. The main parameters of solutions for the development of WiMAX subscriber equipment

Base stations

Let's consider the options for the development of WiMAX base stations based on well-known chips. Fujitsu has developed the MB87M3400 chip for both base and subscriber stations. However, unlike Intel's solution, the Fujitsu chip has an interface for an external processor. To implement full duplex mode, two chips are required, one of which performs the functions of the physical layer and the lower layer of the MAC protocol, and the second is an external processor (third party) for implementing the upper layer of the MAC protocol. For base station development, Fujitsu provides a full duplex development kit with the Freescale MPC8560 processor, but does not provide software for the upper layer of the MAC protocol.

PicoChip offers a PC102 / PC8520 solution built on its two parallel PC102 processors. The company provides software that implements the physical layer and functions of the lower layer of the MAC protocol on PC102 chips. Like Fujitsu, PicoChip uses a Freescale MPC8565 processor to implement the upper layer MAC protocol in its development kit. However, unlike Fujitsu, PicoChip licensed its software for the upper layer MAC protocol. Since the PC102 / PC8520 solution does not include encryption-decryption functions, an external processor must be used to perform them.

The SQN2010 base station development chip from Sequans is the first system-on-a-chip to feature full duplex. The SQN2010 implements all the physical and MAC layer functions required for full duplex base station operation. The SQN2010 chip differs from the SQN1010 in the presence of a second central processor that implements the upper layer of the MAC protocol. The SQN1010 chip has a PCI interface for connecting an external processor.

Wavesat's DM256 / MC336 solution can also be used to develop base stations. This solution supports full-duplex operation, but it should be noted that it requires an external processor to implement encryption-decryption functions. Like Fujitsu, Wavesat does not provide the upper layer MAC software needed to design base stations.

Of the four solutions described, only PicoChip PC102 chips do not integrate ADC / DAC functions. Therefore, designs that use an analog radio interface will additionally require ADC / DAC devices. The main parameters of the considered solutions for the development of base stations are presented in table. 3.

Table 3. The main parameters of the considered solutions for the development of base stations WiMAX

Choosing a chip manufacturer for WiMAX systems development is an important strategic decision. Fast and efficient system development requires the most complete software and hardware support and tools for development and debugging. The availability of debugging kits allows you to significantly increase the speed and reduce the cost of developing WiMAX equipment, which is one of the main criteria when choosing a particular product.

Deployment of WiMAX systems

The construction of a fixed wireless access network involves the use of three types of equipment - base stations, subscriber stations and equipment for organizing communication between base stations. Both narrow directional antennas and antennas with a wider coverage sector, up to omnidirectional ones, will find application in WiMAX-based access networks.

Network topology

For a point-to-point connection (Fig. 6a), two antennas directed at each other are used; this is how, for example, radio relay transmission lines are built, in which the distance between adjacent relay towers can be tens of kilometers. In a point-to-multipoint topology (Fig. 6b), a base station with an omnidirectional or sector antenna is placed in the center of the cell, and all subscribers served by it are equipped with directional antennas focused on it.

Rice. 6. Possible WiMAX network topologies

Another type of communication will be obtained using only omnidirectional antennas. In this case, it will be possible to connect "everyone to everyone", or "multipoint-multipoint" (mesh) (Fig. 6c).

A WiMAX base station is a modular solution that can be supplemented as needed with various blocks, for example, modules for communication with the provider's backbone network. In the minimum configuration, a radio interface module and a wired network connection module are installed.

Frequency range

When choosing WiMAX equipment, in addition to its technical characteristics and price, an important and often decisive factor is such a factor as the difficulties specific to Russia in obtaining frequency permits. The fact is that there are practically no “license-free” bands in Russia. For different types of equipment, there is a different procedure for obtaining frequency permits. To work in any bands, telecom operators must obtain sufficiently complex and multi-level permissions of both frequency services and communication supervision services.

Obviously, in our country, the main factor affecting the speed of implementation of WiMAX systems is spectrum regulation, since the development of the WiMAX services market directly depends on the allocation of the necessary frequency resource to operators. Today, the most promising from the point of view of the future development of WiMAX technology are the ranges in the 2.4, 3.5 and 5.6 GHz region.

It should be borne in mind that the propagation of radio waves in different parts of the spectrum has its own characteristics, which largely determine the range of the equipment, as well as resistance to multipath.

General approaches to choosing a WiMAX system

Before considering available WiMAX systems, the following system issues need to be addressed:

• Frequency range selection.
• Determination of the required frequency resource.
• Development of procedures for the allocation and assignment of radio frequencies.
• Elaboration of legislative issues.
• Before proceeding to the consideration of specific systems, it is advisable to consider the general questions of the choice of systems, which will help to discard clearly unacceptable options at the preliminary stage of the analysis. Let us formulate the criteria that should be followed when choosing equipment for fixed WiMAX wireless access:
• The equipment should be manufactured by a specialized company with experience in the design and manufacture of wireless equipment, which is some guarantee of quality.
• The technical specifications of the equipment provided by the manufacturer must be complete enough to make it possible to draw conclusions about its capabilities. The presentation of such characteristics speaks of the professionalism of the employees and, to a certain extent, ensures that we are talking about the original product, and not about the resale of a little-known brand under the brand name of the seller.
• It is desirable that the base station has the ability to sectorize and gradually increase performance, for which it must be able to connect an external antenna. Then, at the first stage, one base station with an omnidirectional antenna is enough, at the next - two, with antennas with a pattern width of 180 °, and so on.
• The equipment must be certified.
• It should be possible to obtain permission to use frequencies in the ranges used by the equipment.
• The system must have an acceptable cost, and the minimum cost of subscriber equipment is primarily important.

Conclusion

It is obvious that today WiMAX is one of the most advanced and promising technologies for wireless data transmission. By joining the efforts of equipment manufacturers and telecom operators, WiMAX can become a real replacement for DSL and cable connections, providing subscribers with the necessary service in large cities and in the periphery.

Literature

1. www.wimaxforum.org
2. Wide-band Orthogonal Frequency Division Multiplexing (W-OFDM), www.wi-lan.com
3. Marchenko S. Sources of vulnerabilities in wireless networks // ADE. 2004. No. 13.
4. IEEE Std 802.16 ™ -2004 IEEE Standard for Local and metropolitan area networks. Part 16: Air Interface for Fixed Broadband Wireless Access Systems, www. ieee. org.
5. Vlasov V. A. Frequency regulation and information security for Wi-Fi and WiMAX equipment, // "Bulletin of communications". 2005. No. 9.
6. Bob Wheeler. How to choose the best SoC for your WiMAX design // Wireless Net DesignLine. Oct 17, 2005.
7. Pisarev Yu. Choice of a fixed wireless access system: an attempt at a systematic approach // "Information telecommunication networks" (Kazakhstan). 2003. No. 4.

Today, WiMAX wireless communication technology is the most advanced of all existing ones. Appearing back in 2003, it was aimed at satisfying the broadcast market.

Around the world, a large number of operators have started building wireless networks. Such networks now exist in the USA, Japan, Korea, Russia and many others. Taking into account the words of leading analysts in the field of communications, then WiMAX will soon have more than 100 million network users.

Today we can safely say that WiMAX has no alternative technology, which makes it an advanced product. In this article, we will take a closer look at the features of this technology, its advantages and disadvantages.

What it is?

"WiMAX" ("International Interaction for Microwave Access") is a technology developed in 2003 to provide wireless connectivity for workstations, desktops, laptop computers and mobile devices. Based on the "IEEE 802.16" communication standard.

What tasks does WiMAX solve:

• providing broadband communications instead of leased lines and "DSL / ADSL";
• provision of remote monitoring systems;
• creation of remote access points that are not tied to geographic location;
• provision of Wi-Fi access points and their connection with each other, as well as other zones of the Internet network.

I would also like to briefly talk about the main stages of the development of this technology:

Scope and feasibility of application

Today developers all over the world face the acute problem of the "last mile" (the channel that connects the user's terminal equipment with the provider's access point). Fortunately, there are now many varieties of last mile technology that make it easy for any provider to choose this technology.

Today the problem of the last mile does not have a clear and universal solution. Absolutely every existing technology has its own area of ​​application, pros and cons.

A large number of factors can influence the choice of a certain technology, and here are the main ones:

• way to achieve the set goals, efficient use of resources, target audience,
• allocation of investments that will subsequently go to the development of the network;
• availability and operability of the existing network infrastructure, as well as certain resources that will be used to support the technical operation of the network.

Each of the above factors plays a special role in the selection of a technological solution.

I would also like to note, comparing Wi-Fi and WiMAX, that the latter allows users to access the Internet at a fairly high speed. The coverage of WiMAX networks is much greater than that of Wi-Fi.

video: WiMax technology

Technology options

The entire family of WiMAX technology has a fairly wide range of advantages, which have certain differences from each other. Developers of WiMAX technology tried to find the most appropriate option for mobile and fixed use.

However, it is worth noting the fact that the combination of requirements within the framework of one standard is still an unsolved problem. The standard requirements are completely similar to each other, but at the same time, each technology has a specific focus on different areas of the market. Therefore, this was the impetus for creating two separate versions of the standard.

Photo: IEEE 802.16 e and d technology

Each WiMAX specification has its own technical characteristics: radiated power, frequencies, access and transmission, reuse of radio frequencies. And it is precisely because of these features of the WiMAX systems, based on the IEEE 802.16 e and d standards, that they have practically no compatibility.

• 802.16-2004 - Was approved in 2004. During operation, frequency multiplexing is used. In addition, there is support for the so-called fixed access in those areas where there is no line of sight. In most cases, the frequencies used are 3.5 and 5 GHz.
• 802.16-2005 - was approved in 2005. The new version is a big step in the evolution of fixed access. The new version received support for mobile subscribers, and its distinguishing feature is the support of a number of special functions, such as: "Idle mode", "Handover".

Distinctive features between the two specifications are that only static subscribers work due to fixed WiMAX (802.16-2004), and when 802.16-2005 (mobile WiMAX) work, subscribers who move at speeds of up to 110 kilometers per hour work.

I would also like to note that due to mobility, all roaming functions and the so-called "seamless connection" between the main workstations are provided while the subscriber is on the move. There are also exceptional cases when 802.16-2005 can be used quite well when serving static subscribers.

I would also like to note that most companies give their preference to WiMAX, providing high-speed communication services.

And there are reasons for this:

• first of all, 802.16 is effective from an economic point of view when providing its customers with access to the network, as well as expanding services and covering new territories;
• secondly, it is ease of use, in contrast to wired channels. WiMAX and Wi-Fi are fairly easy to use, deploy, and of course scale up. Quite a convenient way to create a large enough network in the shortest possible time.

WiMAX subscriber equipment

Currently, equipment for using WiMAX networks can be installed indoors (such devices are usually no larger than traditional DSL modems) and outdoors (laptop-sized devices).

Indoor devices are more convenient to use, but can only work at short distances from the base station.

Because of this, equipment that is installed indoors requires a larger investment, since a large number of access points will be required to ensure quality work.

Working principle and concepts

WiMAX consists of the following elements: stations (base and client), equipment that is a link between stations, an Internet network. For the connection between the base station and the client, frequencies from 2 to 11 GHz are used.

Line-of-sight is usually established between base stations and an operating frequency range of 10 to 66 GHz is used. The line of sight between workstations and the frequency range allow for data exchange rates of up to 120 Mbps. But at the same time, one of the workstations must be connected to the provider's network using the standard wired connection method.

IEEE 802.16 standards have a GSM network structure. The range of base stations in several kilometers and the construction of any additional towers that amplify the signal is absolutely not required.

Modes

The wimax 802.16e-2005 standard includes all versions that were released earlier:

MAC / link layer

In 802.16 MAC networks, a so-called scheduling algorithm is used. The principle of operation of this algorithm is based on the following: absolutely any client station can connect to the access point, and after connecting, a separate slot will be automatically created for it directly on the access point. In addition, other users cannot influence this and thus it excludes a disconnection.

WiMAX Architecture

At the WiMAX Forum, an architecture specification was created, thanks to which it is possible to define a huge number of nuances of work. This number includes the distribution of network addresses, interaction with other networks, authentication.

I would like to note that the network architecture is not strictly tied to a particular configuration, therefore, a fairly high flexibility and scalability is provided.

Advantages and disadvantages

The benefits include:

The disadvantages include I am:

• shortage of frequency devices;
• unpreparedness of the legislative base;
• difficulties in the implementation of new technology, which is why at the moment there is no possibility of providing high-quality communication at a low cost.

In this article, we took a closer look at WiMAX. It's safe to say that WiMAX is currently the leading wireless technology. Today it has gained quite wide popularity in the modern world.