5G: Stop, Collaborate & Transition
White Paper /
It won’t be long before we will begin seeing the first real world testing and deployment of 5G networks. While these early individual deployments are planned to be relatively narrow in scope, the full rollout of worldwide 5G will be a wide ranging, transformative global effort requiring significant collaboration between the engineering community, standards bodies, and wireless operators. This InterDigital eBook addresses many questions that have come up about this complexity in recent months and discusses the collaborations and integrations that will need to happen in order for this next transition to take place as smoothly as possible.
It won?t be long before we will begin seeing the first real
world testing and deployment of 5G networks. While
these early individual deployments are planned to be
relatively narrow in scope, the full rollout of worldwide
5G will be a wide ranging, transformative global effort
requiring significant collaboration between the engineering
community, standards bodies, and wireless operators. Many
questions have come up about this complexity in recent
months, so we wanted to take a moment to address some
of them and discuss the collaborations and integrations
that will need to happen in order for this next transition to
take place as smoothly as possible.
What?s the plan for the new 5G
RAN - is it going to be designed
from scratch for NR or will
previous RAN design be re-used?
The 5G RAN will have some significant differences,
but will have parts that are similar to the 4G RAN.
When designing a new system like NR, 3GPP RAN will
always look to reuse as much as possible. However,
given the new requirements and use cases for NR, a
number of significant changes will need to be made. For
example, the 5G RAN will have very tight interworking
with the LTE 4G radio/base stations, so there will be
commonalities in how these systems work together.
Can we leverage the current
network architecture (network
elements, hardware, access/
transport data, switches etc.) to
support 5G/IMT-2020 or do we
have to build it from scratch?
The 5G core network will look much different than the 4G network. It will
have some radical changes to allow for virtualization, network slicing and
a new Quality of Service architecture. However, these changes will allow
much more flexibility in how the network is deployed. Network hardware
will be more generic, and will allow the network to evolve more easily. For
the 5G RAN, more flexibility in deployment is also a consideration, and
will result in architecture changes, but less so than on the core network
side. There are significant hardware upgrades required on the RAN side
in order to deploy NR. For example, the NR air interface physical layer,
including RF and baseband processing, will require hardware upgrades
from existing LTE deployments.
3GPP and IEEE are very
In what sense can they
collaborate to produce
3GPP and IEEE are very different organizations with
different structures and internal procedures, and currently
they have a loose working arrangement that allows for each
to be formally consulted at the proper time and informed
when decisions are made that effect the other. Looking at
the current market, there are a number of companies that
have interests in each of the bodies. Therefore, there are a
number of companies with a strong Wi-Fi interest within
the 3GPP discussions, and companies with a cellular interest
within the IEEE discussions.
Are there any specific
new frequency bands
In short, yes. In 4G the spectrum in use is below 6GHz, while for 5G,
3GPP is looking at frequencies up to 52GHz and in the future, based
on spectrum decisions that will be made in 2019 by the ITU, the
spectrum that will be considered may extend up to 100GHz. While it is
widely acknowledged that it?s important and beneficial to harmonize
the use of frequency bands on a regional and global basis, this is not
always possible. Ultimately, the decisions about what frequency bands
will be allocated are left to national regulators within each country.
However, those decisions are informed by recommendations and
guidelines developed by the ITU through its World Radiocommunication
5. Do you think that
the 5G waveform will
be a composite of the
Although we know that the 5G waveform is based on an older technology
known as orthogonal frequency-division multiplexing (OFDM), significant
design decisions have yet to be made within the standardization process.
Different channel coding schemes and other variations will be made
so that the physical layer will be able to handle the very divergent
requirements of 5G ? especially across multiple carriers and widely
different use cases. For example, the eMBB (enhanced mobile broadband)
use cases require extremely high data rates, the mMTC (massive machine
type communications) use cases may require servicing of many thousands
of devices simultaneously, and URLLC (ultra reliable low latency
communication) use cases require very fast but reliable transmission. Each
of these groups of use cases need to be supported simultaneously in a
particular base station, thus the radio will need to be flexible enough to
handle the demands of each use case at the same time.
Will the various 5G technologies using
unlicensed 5 GHz spectrum continue to have
their own market segments, or will there
necessarily be winners and losers? Also, 70%
of traffic is on Wi-Fi. Will this continue up to
2020 and beyond? Why or why not?
There will be a significant amount of traffic in unlicensed
spectrum for the foreseeable future. Wi-Fi provides a way
for cheap, basic and nomadic coverage, while cellular
focuses on guarantees for quality of service for mobile
users. Certain use cases will naturally be solved by cellular
approaches using licensed spectrum, while others will
be solved with unlicensed approaches in the 5GHz band
and elsewhere. For example, internet access within the
home will continue to be done most cost effectively by
Wi-Fi. However, there will continue to be a use by cellular
operators to enhance the data rates by using License
Assisted Access (LAA) service in 5G, or a service like
LTE-WLAN Aggregation (LWA) with Wi-Fi access points.
Is there any ITU-R study
to allow mobile operators
to share spectrum
dynamically on demand?
ITU-R working party 1B is working on two new reports: ?Regulatory
tools to support enhanced shared use of the spectrum? and ?Spectrum
management principles, challenges and issues related to dynamic
access to frequency bands.? When completed, these reports will provide
operators with more tools and principles to share spectrum more
dynamically in a regulated manner. Additionally, ITU-R working party 5A
is writing a report specific to sharing with Wi-Fi in the 5 GHz band called
?Study of proposed additional mitigation techniques to facilitate sharing
between RLAN systems and incumbent services.?
If a mobile operator has a green
field deployment opportunity,
would they use LAA, LWA or
Multefire to complement a 4G/5G
Mobile operators will use different strategies depending
on their existing deployments and spectrum availability.
For example, an aspiring mobile operator that does not
have any licensed spectrum would need to deploy either
Multefire or Wi-Fi to serve its customers in unlicensed
spectrum. For operators having existing 4G deployments
and licensed spectrum, they can choose between LAA or
LWA for incorporating unlicensed spectrum. The choice
between these two technologies may depend on a number
of factors, such as whether or not the operator has an
existing Wi-Fi network deployment.
Different RATs have different
benefits that satisfy the different
use cases and requirements
outlined in IMT-2020. When
deciding which RAT each user
equipment/station (UE/STA) will
utilize, where do you think that
network handoff will take place?
A number of decisions in this area haven?t been made yet since we are
early in development of 5G, but one of the aspects of the new core
network is that the interfaces between the core network and the RAN are
planned to be RAT agnostic. This means that the interface between the
core network and RAN for Wi-Fi data and regular cellular data will be the
same. If fully envisioned, this will allow for RAN network control of all of
the connections and which RATs are best to be utilized for a particular
UE/STA. In 4G, the coordination of Wi-Fi and LTE evolved over time with
some UE/STA involvement and some with RAN network involvement. We
believe that all networks in 5G cellular systems will function this way.
How will interference avoidance be
implemented in Wi-Fi with LTE?
What is the progress on defining
test cases so that LTE in unlicensed
band does not degrade Wi-Fi?
Coexistence between LTE eNB and Wi-Fi AP has been studied by
both 3GPP and IEEE/Wi-Fi proponents. The LBT (listen before talk)
mechanism/procedure has been adapted and implemented in a physical
layer for LTE operation as a means for coexistence in unlicensed spectrum,
complying as well with the power density limits by implementing an
appropriate interlaced radio block allocation rule.
In 3GPP RAN4 radio and base station requirements, a specific study is
ongoing for defining appropriate test cases for coexistence of LTE Base
stations with Wi-Fi Access points. The study is scheduled to finish in late
2017 and will lead to a set of agreed test cases.
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