Nature has no bad laws. Generation 5, or what will work after LTE?

Hello! Telecom direction is one of the main ones for Technoserv, and therefore they decided to discuss today the current trends of the telecom and its trends.

Not so long ago, the development of a whole family of technologies and corresponding standards for fifth-generation mobile communication networks, known in scientific circles as IMT-2020, and in broader ones - as 5G, began. However, over the past quarter century, not a single independent cellular network with an operating frequency above 2.1 GHz was commercially successful and was not economically viable.

So what happens in 5G - prospects, technologies, hopes, promises, achievements - and what will we be waiting for in the end after LTE? We deal with all these questions below.

Holographic perspectives

Today, the development of the 5G networks promised by 2020 is largely associated with work in the radio frequency bands up to 80 GHz, namely: 24.25--27.5 GHz; 31.8--33.4 GHz; 37--40.5 GHz; 40.5--42.5 GHz; 45.5--50.2 GHz; 50.4--52.6 GHz; 66--76 GHz and 81--86 GHz. April 3, 2017 may go down in history as the day when the world's first holographic video call was made using 5G networks operating in the 28 GHz band (that is, almost on millimeter waves). Operators Verizon and KT Corporation made this video call. According to various sources, during the demonstration, a KT employee held a hangout with a Verizon employee who appeared as a hologram on a monitor in the building of KT headquarters. According to statements in the press, “this was the first successful interworking data exchange in 5G networks in the world”. KT is developing the technology of online holographic calls as one of the flagship multimedia services based on 5G networks and also intends to launch 360-degree online broadcasting into virtual reality.

It is hard to argue with the fact that the hopes of all progressive mankind are connected with holographic services now, but I remember that 20 years ago we were already lured by “killer video calls” on 3G networks. The latter did not become something outstanding, but the 3G networks (after a long modernization) became famous simply by transferring data. As Stanislaw Jerzy Lec once noted, in reality everything is not as it really is. Therefore, if we translate the above news into a technical language, then contrary to what might have seemed, in fact, that hologram was most likely transmitted via a transcontinental fiber optic channel, at both ends of which 28 GHz radio interfaces were organized. That, in general, does not prove anything special, if not to talk about the location of these radio interfaces, the length, the presence of other subscribers in the network, etc.

Higher and higher

Recall also that almost 20 years ago a wave of LMDS (26--28 GHz) and MVDS (40.5--43.5 GHz) networks was rising, which broke not only about the manufacturers' unwillingness to organize high-speed data transfer. The history of WiMAX networks operating in the 3.5 GHz band did not end with anything outstanding. There were a number of unsuccessful projects, which were mainly engaged in not “recognized mobile operators”, but those who dared to get around them somewhere. However, it did not go around, and all revenues remained with mobile operators.

So what's happening with 5G now? Equipment vendors display fireworks achievements. Here, Ericsson and SoftBank are testing a network at 28 GHz. Telenor and Huawei demonstrated a pre-5G network operating in the E-band (71--76 / 81--86 GHz) with a peak data transfer rate of 70 Gbit / s. The United States Federal Communications Commission (FCC) is considering the possibility of allocating 28, 37, 39 and 64--71 GHz for 5G. It seems that we will soon live ... At the same time, the FCC will receive its next billions from radio frequency auctions.

Physics against

What does physics tell us? She is, as usual, against us. The range of action is rapidly reduced with increasing carrier frequency, and even atmospheric losses contribute to it. The actual range of 200 m for 28 GHz sounded by the companies mentioned above at even higher frequencies will turn into tens of meters and less (and, as practice shows, in real urban conditions everything works much worse than in the laboratory). That is, in fact, 5G networks will be good in a large or small room where there is no Wi-Fi / abvgdeo yet ... and there are no wired channels. It seems that in order to create the Internet of things, the “things” themselves will have to be “pulled out” closer to the base stations, and it is desirable to have direct visibility so as not to install millions of base stations interconnected by 100 Gb / s optical transport.

And, perhaps, everything is much simpler, and the ultra-high-frequency 5G is just the last hope for the next super-profits of the suppliers of mobile communication equipment? And if suddenly it will be possible to draw operators into the game, then life has again been successful for many years to come. And for good reason the deployment of the 5G infrastructure has just been enthusiastically picked up by the Moscow government. In fact, significant investments are needed for its creation, and each base station must be connected exclusively by a high-speed channel (besides, a serious struggle has developed in the cities for laying cables into a very expensive land), therefore, mobile operators will be willing to participate in this process. still a lot. It is possible that they will even soon create some kind of innovative paving slabs with a built-in 5G base station, which will make it possible to easily solve telecommunication problems in any urban development.

Glitter and poverty of brilliant demonstrations

However, in 5G it is not forbidden to apply to low radio bands. That's just Nokia announced the successful implementation of a call on the LTE network operating at 600 MHz. The company used a 20 MHz radio channel and commercially available equipment, including LTE eNodeB and a test terminal. A maximum throughput of 387 Mbps has been achieved. These tests, by the way, coincided with the completion of the auction held by the FCC for the allocation of frequencies in the 600 MHz range for use by mobile operators. Physics is an ally here, and therefore it is expected that the 600 MHz range will significantly improve the LTE coverage outside the city, primarily due to the larger cell size. At the same time, this range can be used to improve user experience in urban areas - by increasing capacity and actually improving the quality of indoor coverage, not to mention radio technology for the Internet of things. In general, this will definitely work.

And all the brilliant demonstrations of recent months in the 5G region with gigabits and dozens of gigabits in the forward and reverse channels, most of which are carried out at 28 GHz, 38 GHz, 60 GHz carrier frequencies, by definition mean work indoors with effective micro / nano / radii pico / femtocell on the order of tens to hundreds of meters and in direct visibility. Even the use of new methods to improve spectral efficiency up to the theoretical limit, such as Polar OFDM or Sparce Codes, as well as class 8 x 8 MIMO matrices, is not able to compensate for the propagation characteristics of radio waves in the millimeter range. In addition, once again we recall that any femtocell network infrastructure does require the provision of each 5G hot-spot with an individual fiber-optic communication channel with a very high bandwidth.

When it comes to the most effective and economical coverage of open spaces, roads, infrastructure elements and the interior of buildings, you have to turn to the good old range below 6 GHz. The empirical evidence of this thesis is the sad and well-known, but carefully ignored by some marketers market fact - over the past quarter century, no independent cellular network with a working frequency above 2.1 GHz (this is the upper limit for 3G / WCDMA networks) has not had commercial success and wealthy was not. On the contrary, when LTE networks were allowed to use the 1800 MHz, 900 MHz and lower bands, they literally conquered the world in just a few years.

But maybe this is the very “homemade truth” about the future of 5G? People, beware ...

Authors publication:
Alexander GOLYSHKO, Systems Analyst, Technoserv Group of Companies
Vitaly SHUB, Deputy General Director, Telecom business area, IPG Photonics Russia (IRE-Polyus)

The article was published in the journal "X" .