What does every engineer need to know about 5G?

Over the past few years, researchers have worked hard to study new concepts and technologies to answer the question: “What is 5G?”

The 3GPP [3rd Generation Partnership Project] Consortium develops and publishes agreed specifications defining wireless standards. He has already scheduled the 5G schedule, and the first definition phase for 5G called New Radio [NR] [new radio] was adopted in early December 2017.


Fig. 1 - the first specification of the NR technology for 5G was approved at the end of 2017, planned updates are planned for 2018

Although the first phase of the NR will differ from the LTE protocol widely used in today's mobile communication, there are similarities between them. The brightest differences between LTE and NR are the bandwidth and the operating frequency. In addition, NR adds new features in radiation concentration, both in analog and digital communications. The table compares the key LTE and NR specifications.

	LTE	NR phase 1
Operating frequency	Up to 6 GHz	Up to 52 GHz
The width of the line	Up to 20 MHz	Up to 100 MHz at a frequency of <6 GHz, up to 1 GHz at a frequency of> 6 GHz
Carrier Consolidation	Up to 32	Up to 16
Analog beam concentration (dynamic)	Not supported	Supported by
Digital beam concentration	Up to 8 layers	Up to 12 layers
Channel coding	Data: turbo coding, control: convolutional coding	Data: LDPC, control: polar coding
Subcarrier	15 kHz	15, 30, 60, 120, 240 kHz
Self-contained subframe	Not supported	Available
Spectrum workload	90% of channel width	Up to 98% of channel width

In order to be in time for the tight deadlines for the implementation of 5G, a step-by-step implementation plan was proposed. The plan consists of two versions of NR: autonomous and embedded. The embedded version will work with LTE eNB as the primary and with the second auxiliary cell NR gNBs (equivalent to eNB in ​​5G NR) connected to the EPC. This version of the standard was approved in December 2017. The diagram shows how it will look like:


Fig. 2

The built-in version 5G NR will make it possible to use the existing infrastructure for the initial introduction of 5G technology. The standalone version is designed to be bottom-up compatible with future versions of wireless standards. Autonomous networks can coexist with combined and work simultaneously. The exact date of the presentation of the autonomous technology has not yet been assigned, but such a scheme was taken into account when developing the first phase of NR. The offline case diagram is shown below:


Fig. 3 ( source )

In addition to participating in a consortium on standardization, Verizon and Korea Telecom (KT) are looking for ways to commercialize technologies prior to 5G. Verizon is trying to deploy permanent wireless access based on the 5G Technical Forum (Verizon 5GTF or V5GTF) in the winter of 2017. V5GTF will operate at 28 GHz and be used to deliver high-speed Internet in “last mile” cases, but will not cover mobile communications. KT, on the other hand, is trying to deploy the prior 5G technology for use in the Winter Olympics. The specifications for these plans have not yet been published.

When discussing 5G, the working frequency caused a heated debate, and now clarity is beginning to appear on this issue. The table provides a summary of the frequencies under consideration based on participation in 3GP.

The importance of millimeter waves

It is important to note that frequencies up to 6 GHz will still play an important role in 5G technology. Companies are looking for ways to increase bandwidth up to five times compared to what is available in LTE. The frequencies listed in the table are a large part of the frequencies considered, but this is not a complete list. For example, T-Mobile plans to use a spectrum in the region of 600 MHz to introduce 5G in the USA.

And although the millimeter frequencies for the first phase of the NR are better defined, depending on the region of implementation, the standard will require several ranges. For example, Chinese regulators have offered the ranges of 24.75-27.5 and 37-42.5 GHz. The FCC in the United States offered 28 GHz and 2 bands from 37–40 GHz. Europeans said that 28 GHz will not work, and they concentrate on the spectrum of 24-27 GHz, as well as 38-39 GHz. Korea and Japan are leaning towards 28 GHz.

A good first step towards understanding the 5G commercialization process will be a clear understanding of the communication standard, but other difficulties will affect the speed of deployment of the technology - both in the development of components and in system design, as well as testing and validating devices. The addition of technologies such as beam concentration requires a change in radio frequency integrated circuits such as amplifiers and transceivers. To minimize system losses, antenna arrays are increasingly integrated into a single chip or module in amplifiers and transceivers. As a result, engineers are no longer able to test these devices using cable tests. Wireless testing that was previously considered invalid becomes mandatory.

Upcoming difficulties with tests and measurements

NR, especially for millimeter waves, is much more complex than LTE. Most of the existing test equipment is not designed to work with a combination of higher carrier frequencies, wider throughput channels and wireless measurements. In fact, even the simplest measurement tasks such as power measurement will have to be rethought in the 5G case, because there is no clear definition and agreement throughout the industry about what it means to get calibrated wireless measurements.

And although the standardization process of the first and second levels of communication is rapidly approaching completion, many problems remain unresolved. So far, 5G has opened a new era in wireless communications and it is clear that this is only the beginning. In the industry of developing, testing and measuring radio frequency integrated circuits, it is time to take advantage of the experience of researchers in the field of wireless technologies and to innovate so that 5G can be implemented at a commercial level.