35 Gbps - as Megafon and Huawei set a 5G speed record
Operators and equipment manufacturers are confidently moving towards 5G, increasing and increasing speed. A year ago, it was 1 Gbit / s, last September Megafon and Nokia demonstrated prototypes of BS and 5G devices with a maximum speed of 5 Gbit / s, and on June 1 of this year, within the framework of the St. Petersburg Megafon Economic Forum, Huawei achieved a maximum speed of 35 Gbit / sec, setting a record for the speed of the mobile Internet. Already on the day of this event, news agencies replicated photos from the event and were noisy about the achieved speed. And today we reveal interesting technical details of the record.
The introduction of the next generation of mobile communications is expected in 2020 (this is fully consistent with the assessment of "new mobile communications technology every 10 years"). As it gets closer to “hour X,” the 5G standard is becoming more pronounced. At the same time, operators and equipment manufacturers are experimenting with frequencies and communication channels, determining the direction of further movement. How successful these experiments are, show the data transfer rates demonstrated in the framework of the regular tests.
About a year ago, MegaFon, along with Huawei, demonstrated a data transfer rate of 1 Gbit / s. This result was obtained by transmitting data on several frequencies simultaneously (using three carriers), which, in turn, was made possible by refarming - the use of frequencies that were originally intended for another technology.
')
Refarming is an inevitable phenomenon in the course of the evolution of communication standards, since the frequency range has long been painted between consumers. From a technical point of view, refarming allows you to optimize the use of the spectrum: with the development of technology, it is possible to “shove” much more data into the same frequency band (it is enough to compare GSM, 2G and subsequent standards). In some countries, refarming can be limited by legislative restrictions, since when allocating frequencies, not only the main user is fixed, but also the communication standard that will be used at this frequency. In Russia, for a number of bands transferred for mobile communication, the principle of technological neutrality has already been adopted, meaning that any generation of a communication standard can be used in a range.
As part of the experiment, Megafon and Huawei involved the frequency of 1800 MHz, which was previously used for GSM networks.
However, experiments continue. The solution, demonstrated this year at the St. Petersburg Economic Forum, instead of aggregating frequencies from different bands, uses for communication between the prototype base station and the subscriber terminal one but very wide frequency band - 2 GHz - in the 70 GHz band (this is one of the possible frequencies of the future 5G standard ). During testing, it was possible to achieve a data transfer rate of 35 Gb / s, which is an absolute record for mobile data transfer.
Although at this stage we talked about testing wireless communication between a stationary prototype base station and a conditionally stationary prototype subscriber device (it was installed on the MegaFon booth and was not mixed up), the development process has to take into account the mobility of subscribers. For this purpose, the fifth generation provides for bimforming, a dynamic change in the directivity pattern of a phased antenna array in the direction of the largest accumulation of subscriber terminals. Megaphone briefly told about the features of this technology.
If you don’t go into technical details, bimforming requires the creation of a complex antenna, but it allows you to partially correct the situation “communication does not work in a crowd” - the base station will simply reorganize the radiation pattern to better cover the direction in which more devices are located.
In the experiment Megafon crowd with subscriber devices was not just a single emitter and complex antenna shape, which forms several beams - two parallel and one at an angle. Yes, the lilac plate with the company logo on the floor is not part of the design, it is a reflector for radio waves:
Nothing supernatural in it, it's just a plate of steel:
The transmission was carried out in the TDD mode - two-way communication with time separation of the receiver and transmitter signals.
As mentioned above, the new standards allow for more information to be transmitted. Perhaps this is also due to the development of computing power of mobile devices, which allows the use of more cunning modulation. In the experiment of Megafon and Huawei, quadrature modulation of 64-QAM was used.
Simplified QAM is a way to transmit several bytes of data in one clock cycle. This is achieved, firstly, due to the fact that not only the signal level changes, but also its phase. And secondly, the amplitude and phase of the signal have several levels. The easiest way is to show this gif:
We see 16 states obtained by a combination of different phase shifts and signal amplitudes. They can put all possible combinations of 4 bits, so for one signal state we can transmit 4 bits at once.
The picture illustrates 16-QAM, but in 64-QAM everything is the same, simply there are more possible states - 64, which means we can transmit not 4, but 6 bits.
It is worth noting that the high carrier frequency, although it allows transmitting a large amount of data, is very easily muffled by any objects on the way.
It is enough to bring the hand to the radiator and the speed on the graph immediately drops. At the same time, we see the signal constellation beginning to crumble - an analogue of the eye diagrams for 64-QAM (well, strictly speaking, not only for it):
The signal constellation allows you to see the "quality" of the transmission and at the same time notice some problems (more details can be found here )
Test zones 5G MegaFon intends to deploy as early as next year during the World Cup. According to the established tradition, new mobile communication standards are being tested during major international events.
Approaching the 5G standard - aggregation and refarming
The introduction of the next generation of mobile communications is expected in 2020 (this is fully consistent with the assessment of "new mobile communications technology every 10 years"). As it gets closer to “hour X,” the 5G standard is becoming more pronounced. At the same time, operators and equipment manufacturers are experimenting with frequencies and communication channels, determining the direction of further movement. How successful these experiments are, show the data transfer rates demonstrated in the framework of the regular tests.
About a year ago, MegaFon, along with Huawei, demonstrated a data transfer rate of 1 Gbit / s. This result was obtained by transmitting data on several frequencies simultaneously (using three carriers), which, in turn, was made possible by refarming - the use of frequencies that were originally intended for another technology.
')
Refarming is an inevitable phenomenon in the course of the evolution of communication standards, since the frequency range has long been painted between consumers. From a technical point of view, refarming allows you to optimize the use of the spectrum: with the development of technology, it is possible to “shove” much more data into the same frequency band (it is enough to compare GSM, 2G and subsequent standards). In some countries, refarming can be limited by legislative restrictions, since when allocating frequencies, not only the main user is fixed, but also the communication standard that will be used at this frequency. In Russia, for a number of bands transferred for mobile communication, the principle of technological neutrality has already been adopted, meaning that any generation of a communication standard can be used in a range.
As part of the experiment, Megafon and Huawei involved the frequency of 1800 MHz, which was previously used for GSM networks.
New experiment - bimforming
However, experiments continue. The solution, demonstrated this year at the St. Petersburg Economic Forum, instead of aggregating frequencies from different bands, uses for communication between the prototype base station and the subscriber terminal one but very wide frequency band - 2 GHz - in the 70 GHz band (this is one of the possible frequencies of the future 5G standard ). During testing, it was possible to achieve a data transfer rate of 35 Gb / s, which is an absolute record for mobile data transfer.
Although at this stage we talked about testing wireless communication between a stationary prototype base station and a conditionally stationary prototype subscriber device (it was installed on the MegaFon booth and was not mixed up), the development process has to take into account the mobility of subscribers. For this purpose, the fifth generation provides for bimforming, a dynamic change in the directivity pattern of a phased antenna array in the direction of the largest accumulation of subscriber terminals. Megaphone briefly told about the features of this technology.
If you don’t go into technical details, bimforming requires the creation of a complex antenna, but it allows you to partially correct the situation “communication does not work in a crowd” - the base station will simply reorganize the radiation pattern to better cover the direction in which more devices are located.
In the experiment Megafon crowd with subscriber devices was not just a single emitter and complex antenna shape, which forms several beams - two parallel and one at an angle. Yes, the lilac plate with the company logo on the floor is not part of the design, it is a reflector for radio waves:
Nothing supernatural in it, it's just a plate of steel:
The transmission was carried out in the TDD mode - two-way communication with time separation of the receiver and transmitter signals.
In a nutshell about QAM
As mentioned above, the new standards allow for more information to be transmitted. Perhaps this is also due to the development of computing power of mobile devices, which allows the use of more cunning modulation. In the experiment of Megafon and Huawei, quadrature modulation of 64-QAM was used.
Simplified QAM is a way to transmit several bytes of data in one clock cycle. This is achieved, firstly, due to the fact that not only the signal level changes, but also its phase. And secondly, the amplitude and phase of the signal have several levels. The easiest way is to show this gif:
We see 16 states obtained by a combination of different phase shifts and signal amplitudes. They can put all possible combinations of 4 bits, so for one signal state we can transmit 4 bits at once.
The picture illustrates 16-QAM, but in 64-QAM everything is the same, simply there are more possible states - 64, which means we can transmit not 4, but 6 bits.
A spoon of tar
It is worth noting that the high carrier frequency, although it allows transmitting a large amount of data, is very easily muffled by any objects on the way.
It is enough to bring the hand to the radiator and the speed on the graph immediately drops. At the same time, we see the signal constellation beginning to crumble - an analogue of the eye diagrams for 64-QAM (well, strictly speaking, not only for it):
The signal constellation allows you to see the "quality" of the transmission and at the same time notice some problems (more details can be found here )
When will subscribers try 5G?
Test zones 5G MegaFon intends to deploy as early as next year during the World Cup. According to the established tradition, new mobile communication standards are being tested during major international events.
Source: https://habr.com/ru/post/337204/
All Articles