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



    Hello! The Telecom direction is one of the main for Technoserv, and therefore decided to discuss today about 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 the scientific community as IMT-2020, and in wider ones as 5G, began. However, over the past quarter century, not a single independent cellular network with an operating frequency above 2.1 GHz has had commercial success and has not been economically sound.


    So what happens in 5G - prospects, technologies, hopes, promises, achievements - and what will happen after LTE? We deal with all these issues below.



    Holographic perspectives


    Today, the development of 5G networks promised by 2020 is largely associated with operation in the radio frequency ranges 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 (i.e., practically on millimeter waves). This call was made by Verizon and KT Corporation. According to various sources, during the demonstration, a KT employee held a video call with a Verizon employee who appeared as a hologram on a monitor in the KT headquarters building. According to the press, “this was the first successful inter-network data exchange in 5G networks.”




    It is difficult to argue that it is with the holographic services that the hopes of all progressive mankind are connected now, but, remember, about 20 years ago, we were already lured by “killer video calls” on 3G networks. The latter did not become something outstanding, but 3G networks (after a long modernization) became famous simply by transferring data. As Stanislav Jerzy Lets once remarked, in reality, everything is not as it really is. Therefore, if we translate the above news into a technical language, then contrary to what it might seem, in fact the very hologram was most likely transmitted via a transcontinental fiber-optic channel, at both ends of which radio interfaces of the 28 GHz band were organized. Which, in general, doesn’t prove anything special, if we don’t talk about the location of these radio interfaces, the length,


    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 was not only broken by the manufacturers' unwillingness to organize high-speed data transmission. The stories with WiMAX networks operating in the 3.5 GHz band did not end with anything outstanding either. There were a number of unsuccessful projects, which were mainly carried out not by “recognized mobile operators”, but by those who dared to circumvent them somewhere. However, he did not go around, and all the income remained with the mobile operators.


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


    Physics vs


    And what does physics tell us? She, as usual, is against us. The range decreases rapidly with increasing carrier frequency, and even atmospheric losses contribute. The real range of 200 meters voiced by the companies mentioned above for 28 GHz at even higher frequencies will turn into tens of meters or less (and, as practice shows, in real city 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 / update ... and no wired channels. It seems that to create the Internet of things, the “things” themselves will have to be “pulled out” closer to the base stations, moreover, it is desirable for direct visibility so as not to install millions of base stations interconnected by optical transport at 100 Gbit / s.


    And, perhaps, everything is much simpler, and the microwave 5G is just the last hope for the next super-profit of mobile equipment suppliers? And if you suddenly manage to draw the operators into the game, then life again succeeded for many years to come. And for good reason the deployment of 5G infrastructure has just been enthusiastically picked up by the Moscow government. In fact, considerable investments are needed for its creation, and each base station must be connected exclusively with a high-speed channel (in addition, a serious struggle has begun in the cities for laying cables in very expensive land), so mobile operators wishing to participate in this process for money will appear still a lot. Perhaps soon they will even create some innovative paving slabs with an integrated 5G base station,


    Shine and poverty of brilliant demonstrations


    However, in 5G it is not forbidden to refer to low radio bands. Just now, 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 was achieved. These tests, by the way, coincided in time with the end of the auction held by the FCC for frequency distribution in the 600 MHz band for use by mobile operators. Physics is an ally here, and therefore it is expected that the 600 MHz range will significantly improve LTE coverage in the countryside, 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 real improvement in the quality of coverage in the premises, not to mention radio technologies for the Internet of things. In general, it will definitely work.


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




    When it comes to the most efficient and economical coverage of open spaces, roads, infrastructure and the inside of buildings, you have to turn to the good old range below 6 GHz. An empirical proof of this thesis is a sad and well-known, but carefully ignored by some marketers market fact - over the past quarter century, not a single independent cellular network with an operating frequency above 2.1 GHz (this is the upper limit for 3G / WCDMA networks) has been commercially successful not wealthy. On the contrary, when LTE networks were allowed to use the 1800 MHz, 900 MHz and lower bands, they conquered the world in just a few years.


    And maybe this is the very “home truth” about the future of 5G? People, be careful ...


    Authors of the publication:
    Alexander GOLYSHKO, Systems Analyst, GK
    Tekhnoserv Vitaly SHUB, Deputy General Director, Telecom Business Area, IPG Photonics Russia (NTO IRE-Polyus)


    The article was published in the IKS journal .


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