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    Published Date: 8-Sep-2019
5G vs WiFi: Expectation and Reality

Recently, the question of the future of Wi-Fi networks has been increasingly discussed in connection with the expected mass construction of fifth-generation cellular networks. Indeed, why do we need Wi-Fi in a world where cellular networks provide billions of people with high-speed Internet access? Will the 5G family of Wi-Fi standards stop developing? Will technology leave the market by completing its “historical mission”? Everyone who answered these questions in the affirmative is dedicated to this article. Everyone else who understands network technology, we hope, it will also be interesting to read.

Despite the apparent importance and consistency, the questions about the rivalry between Wi-Fi and 5G are based on an artificial opposition of related technologies, but different in application models. Most statements about the fragility of Wi-Fi belong to representatives of mobile operators, at the end of the article we will explain why .

In the meantime, let’s try to dispel two misconceptions together – “5G is much faster than Wi-Fi” and “Wi-Fi will die very soon.” First, let’s go back in time and figure out what 5G is and what Wi-Fi is.

Frequency hunger

By 5G, they mean a new generation of mobile communications standards, which, as many believe, will make a new revolution in telecommunications. Meanwhile, a similar view regarding 4G at the time was perhaps more justified. Compared with 3G 4G, it increased the data transfer speed by an order of magnitude, the technology received a completely new radio interface, a new architecture of the core network and a lot of new opportunities for operators (and, as a result, for subscribers). In the case of 5G, there are many changes and improvements, and some of them are very radical. But there is one important fact that is rarely talked about: based on 5G standards, cellular networks of three different categories will be created. These are 5G networks for traditional scenarios of using a cellular network in the 1-6 GHz bands, networks for continuous coverage of the territory and the Internet of things (IoT) at frequencies below 1 GHz and millimeter-wave networks. And only the first of these three types of 5G will be widely available for ordinary mobile subscribers in the foreseeable future. The other two types will have special usage patterns, which we will also talk about.

But first about the burning issue – about “supersonic speeds” for subscribers. 5G networks operating in more or less familiar frequency ranges from 1 to 6 GHz will be designed for mass servicing of ordinary subscribers. At higher frequencies, it is almost impossible to provide continuous coverage with a limited number of powerful base stations (macro cells). Unfortunately, there are few free frequencies below 6 GHz, and this is a worldwide problem. With 3G and 4G, we have already gone through and continue to go through the conversion of parts of the spectrum, the transfer of various kinds of consumers to other frequency ranges, in the future, frequency re-framing from older standards to newer ones. Obviously, there is no magic new source of free frequencies for 5G in the usual ranges. Actually a large group of new 5G solutions is precisely aimed at mitigating the problem of a lack of frequency resources. The goal of new ideas and technologies in cellular communications is always to increase the capacity and speed of the network without significantly increasing its cost. What exactly can you come up with to approach this goal? And what exactly does 5G offer for this?

Wi-Fi to the rescue

To increase the capacity and speed of the network, new frequencies could be obtained. As already mentioned, by and large, there is nowhere to take them from, so cellular communication is trying to go into the ranges that are occupied by other technologies. In 5G, methods for using Wi-Fi frequencies with cellular communications , which already have a number of implementations in 4G, are further developed . For Wi-Fi in the world, quite large sections of the spectrum (hundreds of megahertz) in the 1-6 GHz band are allocated, and mobile operators have been hunting for them for a long time.

But you simply can’t take these frequencies from public networks, so a family of technologies is being developed that allows using these frequencies simultaneously for Wi-Fi and cellular communications, without significant harm to the quality of Wi-Fi. This is an interesting trend. From the simple reuse of the shared band in LTE-U technology (poorly coordinated and harmful Wi-Fi), the development went first to LAA technology (supported by 3GPP Release 13), using the Listen Before Talk (LBT) principle, and then to the LWA and eLAA standards. They no longer simply determine the method of sharing frequencies, but also describe the direct coordination technique (through integration and data exchange) of Wi-Fi and cellular radio subsystems (supported with Release 13 and 14, respectively). Here the most important trend is the coordination and cooperation of cellular networks and Wi-Fi. Remember him. Will these technologies affect the expected speed and capacity of cellular networks? Of course, with the help of this trend, a certain increase in these parameters can be ensured, but a revolution here should not be expected.

5G Growth Hormones

If there are not enough frequencies, you need to increase the spectral efficiency- in the same frequency band transmit more data in one channel. Here 5G is better than 4G due to updates in the modulation and coding schemes of the signal, but no radical progress can be expected. Modern modulation systems are already close to physical limits and the practically achievable spectral efficiency of cellular communications in a single channel cannot be radically increased. By the way, in the transition from 3G to 4G, the increase in the spectral efficiency of a single channel was more significant than expected in the transition to 5G. Nevertheless, there is still a significant potential for increasing the efficiency of using the frequency band for the provision of services, but it is realized by more complex means. This is the distribution of the frequency resource between network services, more efficient division of the resource between the upstream and downstream data transmission channel, self-organization of the network, resource recombination and cell coordination, improved support for multi-frequency (carrier aggregation), etc. All this will be actively used in 5G and will have a positive effect, but most of these approaches are already present and developing in the fourth generation.

If it is impossible to radically improve the efficiency of using a single channel, it is logical to try to organize simultaneous exchange of different data streams between the network and the subscriber or subscribers in the same frequency band. In other words, it is necessary to increase the level of reuse of the frequency resource. To do this, data channels operating in the same frequency must be isolated from each other in order to avoid mutual interference. There are several approaches to solving this problem, mainly used for a long time in existing cellular networks and further developed in 5G.

The growth in the capacity of cellular networks has always been ensured by a combination of the three factors listed above: the expansion of the spectrum used, the increase in spectral efficiency and the increase in the frequency reuse level. Over the past two decades, the focus has been on reuse techniques and they have contributed a major increase to capacity expansion. According to various estimates, over the entire period of the existence of cellular communications, the capacity due to the frequency resource has grown 3-4 times, due to the increase in spectral efficiency by 5-6 times, and due to improved use of frequencies – by 40-60 times.

All of the above can give a significant increase in the capacity of 5G cellular networks operating in standard frequency ranges compared to 4G, but cannot give any breakthrough growth in the communication speed available to an individual subscriber. The concepts of capacity and data rate in a cellular network are closely related, but not equivalent. The increase in the number of subscribers that the network can serve without loss of quality does not mean that the network will work much faster for each individual subscriber in real conditions.

It must be emphasized that to get a significant effect from the innovations described above, you will have to install more base stations, connect them to packet data networks with increased bandwidth, use much more complex and expensive antenna systems and get more spectrum. No magic very large investments are needed and they usually invest wherever there is a business. For mobile operators, it is not yet clear why to invest huge amounts of money in the mass segment of 5G networks with continuous coverage and high capacity.

Network for IoT and Superior 4G

Let us briefly dwell on other types of 5G networks. The most important of these is the inter-machine communication network or IoT (Internet Of Things). Here 5G has great advantages over previous generations of cellular communications. This is, first of all, a low level of delay (an order of magnitude lower than in 4G) and the ability to serve a very large number of subscribers in the coverage area of ​​one cell. 5G standards include communication protocols of the LPWA category (Low Power Wide Area), which are designed for low-speed, low-intensity communication of a very large number of subscribers at a very low level of power consumption of modems. Thanks to the architecture and parameters of 5G, it is possible to build not only sensor networks (combining different sensors and actuators, for example, urban systems), but also highly reliable vehicle control systems (cars and drones) and various robots and robotic complexes. IoT 5G networks will mainly be built at frequencies below 1 GHz, where the area covered by the signal of one cell is much larger than at higher frequencies. At the same time, high-speed communication at these 5G frequencies for ordinary subscribers is unlikely to be available, due to lack of spectrum and because Massive MIMO at frequencies below 1 GHz is difficult to use due to the large size of the antennas.

The third type of 5G network is designed to provide subscribers with very high speed communications. This is about peak speeds of up to tens of gigabits per second. These are networks in the high-frequency ranges with wavelengths less than one centimeter (millimeter ranges) that have never been used for cellular communications before. The reason for deciding to include these ranges in the 5G standard is that they have very large unallocated spectral regions (many hundreds of megahertz).

A lot of people who argue about a significant increase in communication speed in 5G do not fully realize that ultrahigh speeds will be available only in millimeter-band networks. The signals of these frequencies are distributed in such a way that direct visibility between the antennas of the transmitter and receiver is almost always necessary for communication (that is, the signal practically does not go around obstacles), and the allowed (and technically available) radiation power is very small. This means that in the conditions of the city to build a field of continuous coverage in the millimeter range, you need to install a huge number of small cells.

Publicly available estimates show that for large cities the number of cells will need to be increased 500-1000 times, compared with the number of cells sufficient to form coverage in standard ranges. Unfortunately, even this will not ensure continuity of communication (the subscriber is unsuccessful enough to turn around to block the signal from the base station). There is no other practical way to create a continuous cover (except for projects using drones and balloons). That is, the 5G millimeter-wave network with continuous coverage in the city will turn out to be very expensive, it is almost impossible to reuse the existing infrastructure and it is poorly suited for ordinary subscribers who move freely in the coverage area. In addition, there is no subscriber equipment for communication in the millimeter range, suitable for embedding in standard smartphones and tablets, and in the near future they are unlikely to appear. For the above reasons, this type of network will be used in the medium term to solve various tasks of transmitting data to stationary (for example, houses) or regularly moving (trains, cars, city transport) objects, as well as for organizing individual hotspots, but not for ordinary ones mobile subscribers.

These are far from all 5G features, but an intermediate conclusion can already be formulated. In the medium term (we would estimate it at 5-7 years, but this is a subjective assessment), subscribers will not receive any revolutionary effect from the construction of 5G networks. Their user experience with the advent of smartphones and 5G-enabled coverage areas will improve due to a higher and more stable network performance and a higher data transfer speed available to them. During this period, 5G networks will be perceived by subscribers, rather, as an improved 4G. The data transfer rate when covering 5G and a device supporting it (we are not talking about the pace of appearance of 5G devices on the market) will usually be higher, but will remain in the same order of magnitude. If now in ideal conditions you can see peak speeds above 100-150 Mbps in commercial LTE networks,

5G in buildings

Above we considered cellular networks outdoors. The indoor situation has a number of features. It is there that most of the traffic is consumed, including mobile. Therefore, it is important for mobile operators to provide high-quality coverage and high network bandwidth in urban buildings. Since the most probable spectral regions available for 5G communication will be located in the vicinity of 3-4 GHz, macro-cells located on the street will not be able to form high-quality coverage inside urban buildings due to the strong absorption of the radio signal at these frequencies in the walls. Therefore, the 5G signal will have to come from antennas located directly in buildings. Indoors, the use of high-order MIMO, as a rule, does not have technical and economic meaning, therefore, indoor 5G will use small cells and antenna systems similar to those used today for 4G indoor networks. For this reason, the data transfer speeds that will be available in rooms of 5G subscribers at frequencies below 6 GHz will be the same order that can be obtained today in 4G indoor networks.

Currently, most of the traffic consumed by users of smartphones and tablets is not created on cellular networks, but on Wi-Fi networks. For example, according to Mediascope in Russia, 78% of mobile device traffic goes through Wi-Fi and only 22% through cellular networks. And this traffic is mainly consumed indoors. To change the situation, it is necessary not only that the cellular network provides a higher data transfer rate than Wi-Fi (this is often the case now), but also that this speed is available in public places, and in the homes and apartments of subscribers. Solving this problem for 5G will require a huge investment in the construction of indoor networks, including in residential buildings.

Wi-Fi is no worse than 5G and that’s why

Now, after a brief educational program about 5G, consider the main issue. And how is Wi-Fi different from 4 / 5G and how is it, in fact, worse or better than cellular? The idea of ​​Wi-Fi as a technology is largely shaped by the experience of using existing public networks, which are arranged very primitively. Meanwhile, modern Wi-Fi is capable in the field of data transmission of practically everything that cellular networks are capable of. Wi-Fi fully supports mobility, allowing you to build continuous coverage areas and serve moving subscribers, service classes, automatic network authorization, advanced data protection, automatic roaming between Wi-Fi networks of different operators.Moreover, both the 3GPP cellular standards and the IEEE Wi-Fi standards provide many means for sharing and coordinating the work of Wi-Fi and 4 / 5G. These are the previously mentioned technologies of the LAA / LWA families, and Wi-Fi Calling, and roaming between cellular networks and Wi-Fi networks with automatic network selection. From the point of view of the Wi-Fi data transfer method, both 4G and 5G are very close, since the standards of the 802.11 family use the OFDM modulation method, and in modern versions – OFDMA, which is almost similar to that used in 4 / 5G cellular networks. There are many features and differences, but fundamentally the methods and available modulation and encoding levels of Wi-Fi and 4 / 5G are close (much closer than 3G and 4G to each other), which means that the spectral efficiency in a single channel is similar.

It must be emphasized that Wi-Fi is developing in parallel with cellular networks, but always ahead of cellular standards in terms of supported data rates over short distances. Over the past 10 years, as in mobile communications, there has been one big change in the generation of Wi-Fi standards. Modern 802.11ac has virtually replaced 802.11n (adopted in September 2009) from the product lines of equipment manufacturers. But if in mobile communications the replacement of standards is accompanied by significant and expensive infrastructure transformations due to limited or absent backward compatibility between generations of communications, then Wi-Fi is developing much more smoothly. 802.11ac is fully backward compatible with 802.11n and does not require major conversions to use it on existing networks. Since 802. 11ac is the de facto standard for today, it is logical to compare its parameters with the parameters of 4G networks available now. IEEE uses the approach of introducing standards “in waves” (however, like 3GPP) and 802.11ac has already passed the first wave stage (Wave 1) and is now at the Wave 2 stage. The standard provides for the use of Multi User MIMO (which was previously not the case in Wi-Fi was), and the peak speed of the physical channel (PHY rate) available at this stage is 2.34 Gbps using three spatial streams and a frequency band of 160 MHz (four streams can theoretically be used). The real peak peak data rate at this channel speed can be around 1.5 Gbps. 802.11ac Wave 1 offered channel / real speeds up to 1.3 / 0.8 Gbps, and the “old man” 802.11n in the 40 MHz band up to 450/300 Mbps with three streams. The full implementation of the IEEE 802.11ac specification expected in the near future will allow using up to eight spatial streams, receiving a physical channel of up to 6.77 Gbps and achievable peak data rates of up to 4.5 Gbps. In existing high-quality Wi-Fi networks (there are such ones), one can observe peak speeds of 100-150 Mbps when using mobile devices and higher than 200 Mbps when using modern laptops, even on the equipment of the latest versions of the outdated 802.11n standard. Replacing 802.11ac, the new 802.11ax standard (the first approved version is expected in 2019) will add about 40% of the spectral efficiency in a single channel and a fourfold increase in the overall efficiency of using the available frequency band. There is also the standard 802.11ad, which, like the millimeter “part” of 5G, Designed for high-speed communications at ultra-high frequencies (in this case, 60 GHz). This standard defines a peak channel bandwidth of 7 Gbps and supports bimforming. Unlike the millimeter portion of 5G, for 802.11ad there are already a number of mass-produced chipsets for creating subscriber devices. It is being replaced by the new 802.11ay standard, with theoretical peak PHY rates of up to 44 Gbps in one stream, which will add to the millimeter Wi-Fi Multi User MIMO with support for four streams (that is, theoretical physical bandwidth when using four streams and full bandwidth frequencies up to 176 Gbps), aggregation of channels, and significantly increase the working distance between the client device and the access point (up to hundreds of meters). Finally, to complete the 5G analogy, I’ll mention another new 802 standard. 11ah (which also has the official name Wi-Fi HaLow, which for some reason is pronounced “HayLow”), which describes the connection for IoT in the 900 MHz band. Moreover, in this standard, as in 5G, everything is in order with delays and power consumption. It is clearly seen that the ideology of the development of IEEE standards is close to 3GPP andThe three types of networks described above are also being formed in the Wi-Fi world.

Looking at these numbers, it is logical to ask a question – why, in fact, it is believed that “5G is faster”? The theoretically achievable maximum data transfer rates in 5G networks and Wi-Fi networks are quite comparable. From a technical point of view, 5G will not be faster than Wi-Fi (in fact, in the new Wi-Fi standards for 5 GHz, peak speeds can be higher than in 5G standard ranges, depending on the available frequency resource, and in millimeter ranges will be much above). But in fact, this is not so important. The main difference between cellular networks and Wi-Fi is not in data transfer speed, but in usage models. Now we are ready to formulate it more precisely.

Why Wifi

Cellular networks are designed for mass service of a huge number of subscribers, and in their design they carry an inherited load of those same basic services. Cellular operators are forced to build their infrastructures in such a way as to provide the most uniform user experience, support for all standards and, if possible, all frequency ranges wherever there is network coverage, in any conditions, in a clean field and in conditions of dense urban development, in buildings and outdoors in the air. 5G, by the way, is for the first time trying to systematically move away from this ideology, to rethink it architecturally, offering to build networks of the type that is required (recall three types) exactly where they are in demand.

To this day, Wi-Fi was originally a technology built around only one basic service — data transmission — and focused almost exclusively on areas where there are compactly many relatively inactive subscribers, mainly indoors. At the same time, the set of additional services for Wi-Fi is very different from cellular networks, largely due to the lack of the need for an agreement and the availability of a SIM card. Many of them are available only in such networks: display of advertising when connected, hyperlocal advertising and analytics, short-term paid access for tourists with instant activation. In addition, due to the neutrality of Wi-Fi in relation to mobile networks, traffic offloading, Wi-Fi Calling and international roaming are possible for subscribers of all mobile operators and any Wi-Fi operators.

Typical mass Wi-Fi equipment that meets the standards has significant restrictions on the radiation power and is designed to serve subscribers located at a short distance. It’s easy to see that Wi-Fi is by its nature a niche technology. Due to this, Wi-Fi from the point of view of architecture is much simpler than cellular networks. The most significant simplification is the lack of a single centralized core network in the Wi-Fi ideology, which in the case of cellular communications is not only necessarily present, but also very complex. Each Wi-Fi segment can be built independently, using solutions for processing and routing traffic “in place” and at the same time be controlled centrally by one operator. As a communication environment that provides network unity of such a system, the Internet is perfectly suitable. Another difference is that the ranges in which Wi-Fi operates either do not require licenses and permissions, or have a significantly simplified licensing procedure and lower cost of a frequency resource, compared to frequencies for cellular communications. Due to this Wi-Fi network is much cheaper per unit per subscriber in the coverage area. No matter how the cellular technology changes, the fundamental difference between it and Wi-Fi remains precisely the unit cost of the infrastructure, which allows serving a certain number of subscribers with a given level of service in a given area. Due to this Wi-Fi network is much cheaper per unit per subscriber in the coverage area. No matter how the cellular technology changes, the fundamental difference between it and Wi-Fi remains precisely the unit cost of the infrastructure, which allows serving a certain number of subscribers with a given level of service in a given area. Due to this Wi-Fi network is much cheaper per unit per subscriber in the coverage area. No matter how the cellular technology changes, the fundamental difference between it and Wi-Fi remains precisely the unit cost of the infrastructure, which allows serving a certain number of subscribers with a given level of service in a given area.Wi-Fi is always cheaper.

On the other hand, if you try to build solutions using Wi-Fi to create continuous coverage, service a large number of subscribers outdoors with a single level of service and centralized management of the subscriber base, the result will be worse than in the case of cellular networks, the economic efficiency and quality of which Outperform Wi-Fi far beyond buildings. It should also be remembered that Wi-Fi frequencies are weaker protected than cellular frequencies, and the likelihood of interference in them is much higher. This is not very important in rooms where the situation is usually under the control of the owner, but creates big problems outside the buildings.

Peace as an alternative to war

Cellular operators are worried about the presence of public Wi-Fi networks not at all because their level of quality, usability and security is lower than that of cellular communications, but because they are free. Since mobile operators have never learned to earn seriously on anything other than traffic, the availability of a free, albeit less qualitative alternative to their networks is unacceptable to them. The market has long been offering an alternative to the enmity between cellular communications and Wi-Fi, which consists in downloading traffic of cellular subscribers to the Wi-Fi network (Wi-Fi Offload) in an automatic, transparent mode for the user. The subscriber may not even know through which network his traffic is currently running, since all services (voice communication, data transfer and all types of messaging services) work without any differences. There are many types and technologies of Wi-Fi Offload (for example, Now Wi-Fi Calling is actively developing, which, in fact, belongs to the Offload category), as well as advanced methods of cooperation and coordination of cellular and Wi-Fi networks (some of which are mentioned above in the text), and increasingly cellular and Wi-Fi operators in they are used all over the world. With the advent of modern and high-quality segments of Wi-Fi networks, they become a natural alternative to building or expanding your own infrastructure with increasing traffic or changing generations of the network, or they can limit investment by creating smaller cellular networks.

To build a high-quality Wi-Fi network in an area where there are many subscribers, you need to invest substantial funds (which, although much lower than the corresponding costs of mobile operators, are also quite material). To invest, you need to have a business case. That is, be able to make money on this network. But practically no one can make money on public free Wi-Fi networks. As a result, public Wi-Fi networks for the most part are built with a direct customer and external financing to solve any problems (convenience for visitors, safety, etc.), except for commercial ones. So, such networks are designed to minimize all costs while maintaining the minimum acceptable quality and do not take into account the needs of mobile operators. The experience accumulated over time using such “cheap” networks, in turn, led to the formation of a stereotype of low Wi-Fi quality as technology. In fact, with proper use and quality design, construction and operation, Wi-Fi can provide a user experience no worse than 4G or 5G, but for less money and only where it is advisable to use it. The experience accumulated over time using such “cheap” networks, in turn, led to the formation of a stereotype of low Wi-Fi quality as technology. In fact, with proper use and quality design, construction and operation, Wi-Fi can provide a user experience no worse than 4G or 5G, but for less money and only where it is advisable to use it. The experience accumulated over time using such “cheap” networks, in turn, led to the formation of a stereotype of low Wi-Fi quality as technology.

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