design products & applications – August 2019

16 dpaonthenet.net

Feature: What is 5G?

measurement system, governed by the

Fraunhofer distance that describes the

boundary between near field and far

field. Measurements like modulation

quality, transmit power and receiver

sensitivity need to be made in far field,

where the wave propagation can be de-

scribed as plane wave. The far-field dis-

tance depends on the wavelength and

the dimensions of the antenna aperture

under test.

The larger far-field distances associated

with higher frequencies would require a

very large test chamber, maybe 10 me-

tres or longer, for 5G OTA testing. The

latest Compact Antenna Test Range

(CATR) chambers are an example of the

new generation of laboratory equipment

that is emerging to help overcome these

challenges.

In addition, the temperature sensitivi-

ty of the amplifiers and phase shifters

used for beam forming and steering is

also critical and must be tested. Rapidly

heating or cooling a large test chamber

is impractical, so Rohde & Schwarz has

developed a solution for isolating the en-

vironment around the DUT allowing the

temperature to be varied without affect-

ing the radiation parameters.

Moreover, proper beam-forming opera-

tion can only be verified by performing

tests in three dimensions, which requires

a repeatable 3D positioning mechanism

and a suitable means of recording the

position of the DUT accurately for each

procedure.

New use cases, new priorities

Currently, Release 15 of the 5G specifica-

tion defined by 3GPP, the standards-mak-

ing body, provides the foundation for cur-

rent networks to support 5G enhanced

Mobile Broadband (eMBB) services. The

full diversity of 5G services depends on

additional network capabilities, namely

massive Machine-Type Communications

(mMTC) and Ultra-Reliable Low-Laten-

cy Communication (URLLC), which will

be supported in later SA deployments.

These will allow the more advanced ser-

vices that we expect to see emerging in

sectors such as Industry 4.0, e-health,

autonomous driving, and others.

Already industry-specific groups are

forming, such as the 5G Automotive

Association (5GAA) and the 5G Alliance

for Connected Industry and Automa-

tion (5GACIA), comprising chip makers,

solution integrators, and telecom opera-

tors interested in developing new ideas

that will leverage 5G for automotive and

industrial purposes. The emergence of

these bodies will undoubtedly produce

additional new proposals that will ulti-

mately change the standards as they

apply to 5G infrastructures, devices, ap-

plications, and services.

With these use cases, and others such

as e-health, will come demands for ad-

ditional testing to cover aspects that

influence safety and security, such as

reliability, deterministic low latency, au-

thentication, and encryption.

Because the wide range of 5G services

will place differing requirements on as-

pects such as bandwidth, data volume,

and response time, ensuring Quality of

Service (QoS) is critical if network re-

sources are to be managed efficient-

ly. Ultimately, user perception will be

governed by the Quality of Experience

(QoE). Defining suitable metrics and

determining acceptable thresholds for

each will be far more complex and chal-

lenging than for previous generations,

given the large numbers of devices such

as IoT sensors and connected cars, and

the wide variety of services, that are ex-

pected to take advantage of 5G’s mMTC

and URLCC capabilities.

Make it happen

Until now the 3GPP has had its hands

full developing the specifications to the

extent needed for today’s early commer-

cial deployments to go ahead. In fact,

the current Release 15 of the 5G speci-

fications has been subdivided into three

major parts to support development and

facilitate this. The first “early drop” was

released in December 2017 focusing on

the physical layer, and a second drop

arrived in the middle of 2018 to address

signalling aspects. The third “late drop”

came in June 2019 and defined addition-

al specifications on lower priority archi-

tecture aspects.

While Release 15 aimed to put in place

the fundamentals of the new radio, de-

scribing all the technology details, Re-

lease 16 focuses on the verticals. The

work items we expect to see discussed

here should include the specifications

for URLLC, such as standalone indus-

trial networks, and other new features

and services such as cellular vehi-

cle-to-everything (C-V2X) communica-

tion, 5G broadcast, positioning support

and 5G radio operation in unlicensed

bands. The work items for this release

are currently being defined. As these

become clearer, the industry can work

harder to realise even more of 5G’s po-

tential to touch and change every aspect

of our lives.

http://www.rohde-schwarz.com

About the author:

Reiner Stuhlfauth,

Technology Manager

Wireless, Rohde &

Schwarz

Reiner is responsible

for teaching and

promoting mobile

communication

technology, especially

cellular standards

like: GSM, (E) GPRS,

UMTS, HSPA, LTE,

LTE-Advanced and

5G NR, but also non-

cellular technologies

such as WLAN and

Bluetooth. He is also

involved in a number

of projects concerning

5G. In his role, he links

development and

sales organisations

to coordinate

implementation of

technical features into

Rohde & Schwarz

instruments and

interactively discusses

new requirements

with Rohde & Schwarz

customers. Reiner

is one of a group of

authors within R&S

who have published

a technology book

on 5G NR: “5G New

Radio – Fundamentals,

procedures, testing

aspects”.