Autonomous Vehicle Engineering - March 2021 - 26

Connected Vehicle

Rohde & Schwarz

Network and satellite emulators
such as the Rohde & Schwarz
CMX, CMW and SMB series
used in combination, provide
the toolset to test TCUs in a
controlled and repeatable
environment.

like Wi-Fi/Bluetooth. GNSS simulators, by comparison, can emulate satellite constellations with GPS,
GLONASS, GALILEO, BEIDOU, and QZSS/SBAS
configurations conveniently in a lab environment.
These two types of emulators give users the ease of
testing complex scenarios conveniently in a lab environment. They also provide them with the toolset
to create repeatable tests - often next to impossible
in drive tests where engineers are dependent on live
cellular networks and GNSS signals. The focus is on
protocol stack verification, end-to-end throughput,
user experience, coexistence and interference testing.
Engineers can configure the network emulators to
test user applications with various modulation schemes
and scheduling configurations. Infotainment apps
running on the head unit also use the connectivity path
provided by the TCU to the cloud services. From a user
experience perspective, it is critical to test end-to-end
connectivity between the apps hosted in the cloud and
application clients installed on the head unit.

Protecting from attack

Security analysis is another key area that must be
addressed during the testing phase. Endpoint geolocation, domain name lookup, traffic analysis of encrypted
and unencrypted data, digital certificate analysis, keyword
search and port scanning are some topics that must be
considered while designing the strategy to test TCUs.
While the TCU provides the much-needed connectivity to the vehicle, it can also be the prime target for an
external security attack. PEN, or penetration testing, is
often used to stress-test connected systems to look for
possible security breaches and expose the points that
are vulnerable to a cybersecurity attack. This is critical
for connected as well as autonomous vehicles.
It is vital to create stressful conditions for the TCU
during the testing phase. This makes it essential to test

26 March 2021	

not only in ideal conditions but also test the TCU in
RF faded environments and in presence of interference from other radio frequencies. The coexistence
of multiple wireless technologies inside the TCU as
well as inside the vehicle is something that must be
considered during design and validation.
The vehicle can drive in various weather environments, subjecting the TCU to extreme temperatures. It
is not uncommon to see test engineers considering the
temperature range of -40-deg C to 85-deg C, to test automotive parts. TCU is no exception; the unit can be placed
inside a temperature-controlled chamber to verify that it
works as expected across a wide range of temperatures.

Production tests, TCU future

The focus in the production environment is quite
different than that of feature verification and integration
testing. Automated production line testing is essential,
with the goal to achieve close to zero downtime. Testing
both multiple devices and multiple technologies simultaneously is desirable. The devices are set in factory test
mode (FTM) and testing is geared towards improving
the efficiency on the production line. Automated setups
control multiple RF testers; it is quite common to
consider integrating robotic arms in production settings.
TCU design is evolving at a rapid pace. As cellular
networks across the world move from LTE to 5G
New Radio networks, the TCU needs to be 5G ready.
Development teams should consider software-defined radios along with appropriate RF front end and
antennas that support the 5G frequency range that the
local regulators and cellular operators plan to deploy.
Using this approach allows OEMs to upgrade the TCU
from 4G to 5G simply via software upgrades.
OEMs might consider charging the end customer
for swapping the old 4G TCU with the 5G NR TCU
hardware. Alternatively, this could be done for free if
the OEM sees possibilities of discovering alternative
revenue streams. Such decisions need to align with the
overarching business strategy. ■
Nikhil Kumar recently joined Lucid Motors as senior technical
program manager. He wrote this article in late 2020 while
technical program manager for automotive connectivity at
Rohde & Schwarz.

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Autonomous Vehicle Engineering - March 2021

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