Evaluation Engineering - 22

SOFTWARE

MEETING 5G CHALLENGES FROM CODE
GENERATION TO SPECTRUM CONGESTION
By Rick Nelson, Interim Chief Editor
5G research spans the gamut from
algorithm development to carrieracceptance test, as explained in a special
report in our December issue.1 In that
article, industry experts including Ken
Karnofsky, senior strategist, MathWorks,
commented on trends in 5G technology
and the challenges 5G presents. In a follow-up phone conversation, Karnofsky
elaborated on topics including automatic
code generation, helping engineering
teams obtain the necessary skills and
tools to meet 5G challenges, math-based
visualization of propagation characteristics, scatterers in multipath environments, and issues related to spectrum
congestion and coexistence.
Rick Nelson: In our December special report on 5G, you commented, "Currently,
the entire signal chain, from RF to
baseband, can be implemented in a
single programmable device or module. However, most engineering teams
do not have incumbent engineers with
the expertise to design and integrate
these devices into a complete system."
Are these devices FPGAs?
Ken Karnofsky: It depends on whether
the design is for a base station or mobile
phone. Ultimately in many cases, once devices get into full production, they will
become ASICs. In the early stage of basestation design there is a significant FPGA
component. For handsets and mobile devices FPGAs can be used in emulators or
prototyping systems, but of course the
ultimate final product is going to be an
ASIC in that case.
RN: So, you can develop an algorithm
in MATLAB and translate that to one
of the FPGA design tools?
KK: Yes, that is certainly one aspect of
what we offer. The system architect will be

EVALUATION ENGINEERING FEBRUARY 2020

working with a floating-point algorithm
where they are not really concerned about
the constraints of the physical device, but
they want to understand the behavior and
they might also simulate algorithms in
the context of an end-to-end signal chain
that could include RF impairments or
aspects of the antenna characteristics,
which are becoming more important
with MIMO systems in 5G. Then often
a couple of things can happen. For developing prototype systems there's definitely growing interest in automatically
creating those prototype systems from
the models, which would involve converting the abstract floating-point model to
something that represents the fixed-point
hardware. Some of the architecture could
be implemented in hardware, and the
last stage is generating the code for the
implementation.
As the state-of-the-art for more production-system ASICs or FPGAs, we are
seeing that automatic code generation is
being adopted by some companies-it's
more of a leading-edge type of process for
particular IP blocks or algorithms within
the system. But by and large the overall
system is often hand-coded in VHDL or
Verilog. I am not aware of anyone who
is automating the implementation of an
entire baseband modem-that's a tall order and is somewhere in our future-but
for specific algorithms, we are definitely
seeing more automatic code generation.
RN: What are the advantages of hand
coding?
KK: There are established workflows,
such as verification workflows, and existing tools and skill sets. Adopting a
different methodology is something of
a challenge and is not done lightly, even
when there are compelling advantages for
doing so. But also, there are aspects of the
chip design that really have to do more

with memory management and other
types of components that to date have
not really been a MathWorks focus. We
are starting to introduce capabilities for
modeling those parts of the systems, but
automating the implementation is still in
the future.
RN: You have mentioned that engineering teams may lack needed expertise for
5G. How does MathWorks help with
this-with training or by building more
capabilities into the tools?
KK: Some of both. One aspect we are
seeing as 5G comes online is that there
is a real need and demand for educating
the engineering workforce, which may
be familiar with LTE or other aspects
of communication, but which is new to
5G. And some aspects of 5G in terms of
the flexibility of the standard add a lot of
complexity. And there are some new concepts that are of strong interest every time
we engage with the customer. We've produced a short video series that we call "5G
Explained"-it's a series of about 10 videos
on various aspects of the 5G physical layer.
And when we look at where people go on
our website for information on wireless
topics, the series has climbed into the top
five pages-so there is clearly an interest in
that topic, and we see it when we present
that material at specific customer sites.
Usually, we get a full room of people who
are interested in 5G as well.
So that is one aspect. The other aspect
is more about system modeling where
the baseband meets the RF and antenna
system. So that would involve beamforming architectures, using more digital
algorithms like digital predistortion to
compensate for impairments or nonlinearities in the power amplifiers, and the
large bandwidths that are necessary to get
the 5G data rates. These factors are really
causing a rethinking and rearchitecting

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