20120531 nokia siemens networks deployment strategies for heterogeneous networks final
TRANSCRIPT
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
1/16
White paper
Deployment strategies forHeterogeneous Networks
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
2/162 Deployment strategies for Heterogeneous Networks
The growing demand for affordable
mobile broadband connectivity is driving
the development of Heterogeneous
Networks (HetNets). A range of different
Radio Access Technologies (RATs) and
Wi-Fi will all co-exist, and macro cells
will be complemented by a multitude of
smaller cells, such as micro, pico and
femto cells. Such heterogeneous
systems will be significantly more
complex to deploy than todays
networks and therefore require simple
and robust deployment strategies.
The first step is to ensure mobile
broadband (MBB) coverage, which
involves extending existing macro
base stations, for example, using
lower frequency bands such as
UMTS900 and LTE800.
The next step is to increase
capacity using additional spectrum
(such as 2600 MHz), applying
higher sectorization and adding
more macro base stations. This
Executive summary
Contents
Executive Summary 2
Many technology options 3
for operators
Single RAN Macro 5
layer evolution
Outdoor small cell 7
densification
Indoor small cell offload 9
Cost considerations 12
Nokia Siemens Networks 14
supports operators
Abbreviations 15
combined with site renewal,
for example, by upgrading with
Active Antenna Systems (AAS)
will minimize additional site
acquisition/upgrade costs.
Once all these measures have
been exhausted, deploy outdoor
and indoor base stations to
create smaller cells in congested
network areas, for example hot
zones, but ensure that this
network densification is well
integrated and managed with the
existing Single Radio Access
Network (RAN).
This white paper outlines key
deployment strategies for HetNets and
explains how Nokia Siemens Networks
can help operators to address them. It
discusses how to design roadmaps to
expand the macro layer and how to
use outdoor and indoor small cell
layers to handle the increasing traffic.
Existing
networkOutdoor
small cells
Macro
extension
Offload to indoor
Strategic
decisionOptions
Deployment benefit in priority order
(macro, small cells & indoor independently)
Tilt optimizations Minimize interference to increase
capacity at very low cost
MulticarrierEnhance capacity with high
coverage Including refarming
Sectorization increases both coverage and
capacity without macro site densification6-Sectorization
Provides marginal improvements in capacity
and coverage where there is abundant fiberC-RAN
Deployment for capacity enhancements,
especially in high traffic areasWi-Fi
Deployment for indoor coverage and
capacity for large indoor hot zonesPico cluster
Deployment for coverage but focused on capacity
in indoor public and private hot zonesMicro
Similar to micro cells with low backhaul costPico Cluster
Suitable to provide cost-efficient
coverage in large-sized buildingsDAS
Deployment for capacity enhancements,
especially in high traffic areasFemto
Figure 1. Deployment options for Heterogeneous Networks.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
3/16
The reason for Multi-RAT
deployments is simple. Operators
typically already have wide-area GSM
coverage and HSPA in densely
populated urban areas. Theyre
probably deploying LTE in hotspots/
hot zones or in rural areas in order to
exploit the digital dividend, as is the
case in Germany.
The impact of LTE
The prospects for LTE deploymentover the next three years:
Early adopters launched a data-
only service using USB dongles
before the end of 2010.
By mid-2011 the first wave of LTE
smartphones and tablets were
introduced.
Although 2011 and 2012 are the
key years for commercial
launches, many operators do not
intend to launch commercial LTE
services until 2013 or later.
LTE is expected to reach themass-market threshold in 2014,
based on LTE device availability.
LTE coverage will focus on urban
areas to provide highly scalable
infrastructure to support the
exponential growth of mobile
broadband traffic.
A few operators are targeting
aggressive nationwide rollout,
including rural areas that lack the
wireline infrastructure to support
DSL or fiber optic fixed networks.
Many operators are also considering
re-farming existing GSM frequency
bands to HSPA or LTE, so they can
update their equipment gradually
to more spectrally efficient radio
standards. GSM, HSPA and LTE will
continue to coexist and evolve in the
long term for several reasons:
GSM may be the only system
providing ubiquitous voice
coverage and is being used by a
large population of legacy terminal
users, for example, pre-paid
customers, roamers from foreigncountries, or machine-to-machine
(M2M) applications such as
smart metering.
Many technology options for operators
3Deployment strategies for Heterogeneous Networks
Todays smartphones all rely on
HSPA as the underlying MBB
technology.
The schedule for migration towards
LTE-only networks depends on the
LTE terminal penetration rate and
the availability of attractive LTE
terminals (including voice support).
It will take time to achieve mass
market terminal support for new
3GPP releases and features.
It usually takes 15-18 months
from 3GPP release until the first
commercial devices appear, but ittakes around five years for terminal
penetration to exceed 50%.
However, subsidies can speed up
the process significantly.
The evolving roles of small cells
In the early days of GSM and until
recently with HSPA, small cells were
used mainly for fill-in purposes.
However, small cells will play a key
role in future operators networks with
the large majority of small cell
deployments supporting the macro
layer to add capacity when and
where required.
The cellular standards already mentioned
will continue to exist alongside local area
technologies such as Wi-Fi. In fact,
offloading data traffic from cellular to
Wi-Fi is highly attractive for operators
from a cost point of view, allowing them
to reduce traffic in their HSPA and LTE
networks and use comparatively
inexpensive backhaul infrastructure.
Offloading will mainly take place in
homes and offices. A mobile operator
that also owns the Wi-Fi access
infrastructure can deliver a seamless
data experience for end users in public
premises. It is also expected that all new
smartphones will have Wi-Fi capabilities.
Many networks will include an overlay of
cells of different sizes. For instance,
outdoor terminals may be served by a
combination of macro, micro and pico
cells. Pico cells may provide both
outdoor and indoor coverage/capacity in
hotspots/hot zones such as train stations
or shopping malls, with a typical cell
radius of up to 200 meters. Femto cells
are used indoors in cells of no more than
10-25m radius. While pico cells are
deployed by an operator, femto cells are
typically user-deployed.
Hot Zone not sized up for a single Pico
Macro layerco-existence
Transport andEPC impact
Backhaulconnectivity
MobilityQoS
O&M
Offloading andlocal routing
Performanceand scalability Ease ofinstallation
100K Small cells underlay challenges
Office
building
85Pico Cells
Pedestrian
Zone
15Pico Cells
Capacity problems in Hot Zones
Denseurban Suburban Rural
Figure 2. Hot zones dene the needs for dif ferent and more holistic small cell capacity solutions.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
4/16
WCDMA/HSPA
LTE
Upgrade to 6-sector
Upgrade to 2ndcarrier
Add HSPA macro sites Add HSPA micro cells
Upgrade to 3rdcarrierExisting macro sites Upgrade to 2ndcarrier
Upgrade to 6-sector
Add LTE micro cells
(new or reused HSPA micro sites)
New LTE RAT
at existing HSPA sites
The take-up time of
LTE strongly depends
on spectrum and LTE
terminal availability
4 Deployment strategies for Heterogeneous Networks
Theres also a distinction between
open and closed subscriber group
(OSG/CSG) femto cells, where
CSG cells serve a constrained
set of users. The trend towards
multi-layer deployments, or small cell
densification, is driven by the need to
provide better (indoor) service quality,
for added capacity in hot zones, and to
respond to heterogeneous traffic
demands, as well as by cost and
energy efficiency considerations. But
how can operators determine the right
expansion roadmap?
In most 3G networks today, operators
are also seeing capacity demand in
some areas growing much more
rapidly than in the rest of their
networks. These former hotspots have
effectively evolved into much larger hot
zones, outdoor and indoor areas that
cannot be covered by a single or a few
Micro/Pico cells. Small cells have a key
role to play in supporting capacity and
better subscriber performance in these
hot zones. Yet the nature of such
dense small cell deployments and the
high volumes of new small cells in
operators networks are bringing their
own challenges. This will mean that
operators will need to revisit the
TCO equation to find a cost effective
approach to small cell underlay for
capacity.
An optimal network expansion
roadmap depends on various
operator location-specific
parameters and assumptions,
such as:
The legacy infrastructure in
terms of sites, base stations and
backhaul.
Availability, or lack, of new sites.
Health regulation in terms of
authorized emitted RF power.
The availability of spectrum and
terminals for specific RATs.
Traffic demand, user mobility and
revenue forecasts for a particular
area and the area parameters.
Cost-related aspects (such as
backhaul infrastructure, site
rental, labor and energy).
General strategic decisions
regarding services to be provided
and the metric to be optimized
(such as ubiquitous connectivity
anytime and for anybody versus
peak data rates for certain
consumers).
Figure 3. Example of wide-area expansion roadmap: multi-RAT (HSPA to LTE) and multi-layer (macro to micro).
Establishing an expansion roadmap
requires a holistic performance
evaluation methodology, detailed
cost models and measurement data.
The impact of the uncertainty inherent
in parameters such as traffic forecasts
can be mitigated by investing in flexible
base stations, where changes can be
made later via a software upgrade.
Figure 3 shows an example of a
derived expansion roadmap by Nokia
Siemens Networks in cooperation with
key customers.
The traffic distribution can vary widely
throughout a given network. This,
combined with the practical deployment
limitations of different upgrade options,
means that operators may pursue
several expansion paths simultaneously.
Operators need an automated process
to identify which parts of the network
need upgrading and to identify the best
solution for now and in the future. In the
long run, many operators will also be
managing networks in which equipment
from different vendors is used in the
same geographical area. In this
case, it is particularly important that all
network management functions are
multi-vendor-capable.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
5/16
Figure 5. Nokia Siemens Networks Single RAN Advanced for the macro cell network.
Radio frequency
(Multiband & RAT agnostic)
Baseband
(Multi-RAT)
Shared antenna
Shared multi-radio RF
Multi-band
load balancing
Multi-band carrier
aggregation
Shared backhaul
5
The number of RATs and frequency
variants increases the complexity of
mobile networks. Operators will
typically have three RATs (GSM,
HSPA and LTE) and up to five
frequency variants running in parallel,
as illustrated in Figure 4.
At the same time, network operation
must be simplified and the base
station site solution must be compact.
These requirements can all be
tackled with single RAN base
stations. Single RAN brings benefits
in terms of common antennas and
backhaul transmission between
multiple RATs. Single RAN Advanced
from Nokia Siemens Networks
provides the most compact macro
site solution with future-proof
evolution by software upgrades.
A multi-carrier upgrade is a simple
and cost-efficient method for
upgrading the macro network where
spectrum is available. Refarming part
of the 2G spectrum, such as 850/900
MHz to HSPA enables better MBB
coverage, especially indoors. It also
allows micro/pico cells to be deployed
on the existing 3G spectrum, such as
2100 MHz.
New LTE bands such as 700, 800,
AWS and 2600 MHz are available,
including re-farming the 1800 MHz
band from GSM to LTE. Many
networks were designed based on
voice coverage and with the increase
in data rates the coverage area may
shrink owing to power limitations in
user devices. Therefore, macro site
upgrades may require additional
densification, increased base station
output power or further cell-splitting
or sectorization.
Higher order sectorization can be
deployed in both the horizontal plane
by increasing the number of
antennas/sectors and/or in the
vertical plane by introducing AAS. An
example of sectorization is shown inFigure 6.
Single RAN Macro layer evolution
Figure 4. Typical future single RAN configuration in Europe.
2600 MHz
800 MHz
2100 MHz
1800 MHz
900 MHz
LTE 20 MHz
HSPA 15 MHz
GSM + LTE 10-20 MHz
GSM + HSPA 5 MHz
LTE 10 MHz
Deployment strategies for Heterogeneous Networks
Figure 6. Different sectorization options.
3 sector layout - 3x1 6 sector layout - 6x1 6 sector layout - 3x2
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
6/166 Deployment strategies for Heterogeneous Networks
Many operators are facing challenges
such as lack of new site locations,
challenging operating frequencies with
limited coverage and performance and
ever-growing demand for a high-quality
end-user experience. With multi-
sectorization, operators can improve
their rollout and meet the challenge of
traffic growth by providing more coverage
and more capacity simultaneously, as
well as improving end-user service
quality without having to invest heavily in
new base station sites. Deploying multi-
sectorization will also reduce the need
for new macro sites.
Nokia Siemens Networks provides site
solutions for multi-sectorization
increasing mobile broadband capacity
and coverage as follows:
Up to 80% more capacity for 6x1
deployment (compared to 3x1).
Up to 65% more capacity for 3x2
deployment (compared to 3x1).
Up to 40% increased coverage.
Antenna tilt optimization is a cost-efficient
way to increase the signal-to-interference
noise ratio (SINR) in the macro network.
A typical initial deployment was focused
on coverage and now that capacity is the
limiting factor the antenna tilt can be
optimized in many networks. Figure 7
shows an example of full-scale network
antenna tilt optimization were the median
gain was ~2dB compared to the
deployed network. The tilt settings can
be tuned either by mechanical tilt (on-site
modifications) or by electrical tilt (remote
modifications), which will be used by self-
optimization functions.
C-RAN, also known as Cloud-RAN,
is a scaleable radio-over-fiber-based
centralized network architecture.
With a centralized architecture,
baseband pooling can provide energy
savings for operators and advanced
multi-cell techniques can be introduced
(such as CoMP and joint multi-cell RRM).
However, it provides only marginal
capacity and coverage improvements.
The key pre-requisite for C-RANis an abundance of high-speed
fiber connections.
Figure 7. Example of full-scale HSPA network SINR improvement by tilt optimization.
0
0.2
0.4
0.5
0.8
0.1
0.3
0.7
0.6
1.0
0.9
-5-10 0 5 10
SINR (dB)
15 20 25
Optimized tilt settting
Non-optimized tilt setting
CDF
The macro network still has great
potential for improving both network
coverage and capacity. Recommendedupgrades are summarized in Table 1.
These macro cell enhancements will
delay the need to deploy small cells.
Table 1. Macro cell deployment recommendations.
Macro cell Recommendations
extensions
Tilt optimization Antenna tilt should be optimized based on the current deployment.
This is one of the most cost-efcient ways of optimizing the
macro network.
Multi carrier Refarm spectrum for improved coverage. Use
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
7/16
Figure 8. An example of a full-scale European metropolitan network upgrade.
0
50
100
200
150
250
Macro upgrades
Microcells
Two-carrier Macro upgrades
Two-carrier Micros
#
ofcells
0 2 4 6
Traffic volume multiplier
Number of micro and macro cells, inband micro deployment
7Deployment strategies for Heterogeneous Networks
When traffic increases in mobile
networks, macro cell network capacity
can be increased by the methods
explained in the previous chapter.
Macro cell evolution may still not
be sufficient to provide the required
capacity and coverage enhancements.
Adding more macro sites is expensive,
and it may be a more cost-effective
option to deploy small cells to add
capacity with limited spectrum and
non-uniform traffic demand in hot
zones/spots.
Macro vs micro cells
deployment
Figure 8 shows an example of a
European metropolitan network
upgrade with a deployment of 3G
micro cell and additional macro cell
carriers. The example compares
the number of new macro cells the
operator would need to deploy with
the number of micro cells. The most
efficient deployment of micro cell
versus additional macro carriersdepends on the spectrum availability
and traffic density.
At low to medium traffic density the
network needs the same amount of
microcells regardless of the microcell
carrier frequency. However more
macro cells are needed in the in-band
micro cell deployment. Single carrier
in-band 3G micro deployment is not
feasible for high traffic volumes,
because it requires the deployment of
an excessive number of micro cells.
An out-band micro cell solution gives a
balanced performance and even two-
carrier in-band (or out-band if spectrum
allows) micro is a viable solution.
Furthermore, as the data rate
increases, the coverage area for
each cell may shrink. The link budget
for todays deployment is typicallydesigned for voice data rates in HSPA
and most operators reuse their macro
sites in LTE deployment. Therefore, the
initial deployment of micro cells will be
most efficient at the macro cell edges,
while any further deployment of micro
cells should be positioned based on
traffic density.
Outdoor small cell densication
Table 2. Micro/Pico cell deployment recommendations.
Medium trafc density High trafc density e.g. Hot zones
Suburban/urban areas Dense urban areas
1-2 HSPA carriers Use all carriers for macro. Single macro carrier deployment
1 LTE carrier Eventually consider in-band and out-band micro/pico cell
deployment of micro/pico cells. deployment (when applicable).
3 HSPA carriers Use all but one carrier for Use all but one or two carriers for
2 LTE carriers macro and eventually consider macro and consider (dual) out-band
single out-band micro/pico cell micro/pico cell deployment.
deployment.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
8/168 Deployment strategies for Heterogeneous Networks
In-band versus
out-band deployment
In the performance analysis, we see a
breakeven of in-band vs. out-band
deployment of around five micro cells per
macro site depending on the traffic load.
An in-band solution is more attractive,
with a lower number of micro cells.
Meanwhile out-band performs better with
a high micro cell density. The out-band
deployment is a cost efficient way of
increasing network capacity and
coverage if spectrum is available.
Efficiency is highly dependent on site and
backhaul costs. The in-band deployment
increases network capacity and coverage
and is recommended if spectrum is
limited and macro networks are fully
developed. The cost efficiency is lower
than with out-band micros. The typical
evolution is to start with in-band micro
cells. When the micro cell density
increases and it can carry enough traffic,
the frequency could be fully dedicated to
micro/pico cells.
TX power recommendation
for 3G micro cell deployment
The larger the area of 3G micro
dominance, the more user equipment it
attracts. The dominance area depends on
the transmission (TX) power and the
uplink/downlink (UL/DL) bias of the micro
cell or on the cell selection parameters.
For high traffic volumes the microcells DL
direction may become congested. In this
case its better to provide an additional
micro-carrier than to reduce the micro TXpower. Reducing TX power in outdoor
micro cells together with increased data
rates increases the probability of
coverage holes. Site densification
reduces user equipment TX power rapidly
and reduces the UL interference. For UL-
limited network performance there is no
reason to reduce the microcells TX
power. A microcell TX power of 37dBm
(5W) is recommended for coverage and
some selected hotspots, while 30dBm
(1W) is sufficient for capacity extension in
hotspot/ hot zones areas. Bias in cellselection can be used if microcell
shrinking is desired.
UL vs DL trafc load driving
network upgrade
Some networks are DL performance-
limited while others are UL performance-
limited. The breakeven for UL/DL traffic
load is ~1:5. The ideal network upgrade
depends on which link is currently limiting
the performance. UL performance
limitations often result from a tight link
budget. In this case, additional macro
carriers will not improve the performance
while micro/pico cell deployment at the
cell edges has the biggest impact.
In contrast, a DL-limited network will
immediately gain from the addition of
more macro carriers, since a significant
part of the UL traffic comes from
smartphone signaling. Once traffic grows
further, it is expected that the UL signaling
overhead will not grow at the same rate
as data traffic. The ratio of UL signaling
and downlink traffic will decrease as a
result and growth will arise mainly from
DL traffic growth and increase the UL
performance. Furthermore, UL inference
will be further reduced by 3GPP features
such as CPC in Release 7 and HS-
RACH/HS-FACH in Release 8. The best
solution therefore depends on spectrum
availability, as well as traffic distribution,
macro network layout and long-term
traffic evolution.
Zone deployment of small cells
Deploying small outdoor cells in clusters
can further enhance performance,
reduce TCO, and simplify the backhaulfor small cells. A zone topology deploying
small cells is composed of two key
elements access points and a zone
controller. The zone deploymentenables operators to deliver wireless
broadband access outdoors at street
level using clusters of coordinated small
cells or indoor clusters, for example in
hot zones like shopping malls or
airports, see Figure 9.
The zone architecture can use wireless
Near Line of Sight (NLOS) backhaul to
cost-effectively deliver outdoor street-
level deployments and place the access
point deep into a hot zone for better
performance with only one connection tothe Evolved Packet Core (EPC) for up to
100 access points. The radio
deployment aspects of the access
points remains unchanged, but the
backhaul for the zone deployment
significantly reduces the TCO.
The zone and local controller
architecture further allow interference
and scheduling to be coordinated within
the zone. Even if the same spectrum is
used for the macro network and zone-
deployed cells, the interference isreduced from the macro network, raising
the customer experience. Furthermore,
this hides the access point architecture
from the macro network and thus eases
interworking and management. Also,
thanks to IP offloading and zone level
mobility, it significantly reduces the
EPC cost of extensive small cell
deployments. Finally, with up to
100 access points being managed as
one entity plus Self-Organizing
Networks (SON) for heterogeneous
networks, the operations andmaintenance (O&M) impact and
complexity are reduced significantly.
APAP AP
APAP
APAP
EPC
ZONE
Controller
Traffic offload
Figure 9. Small Cell Zone architecture and deployment.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
9/16
In high-traffic density areas the
recommended first step for macro layercapacity enhancement is to deploy
outdoor out-band lower power micro/
pico cells. However, in dense traffic
hotspots such as train stations,
airports, shopping malls, and office
buildings, indoor cells provide an
additional option to offload traffic using
small nodes such as femto cells, pico
clusters, distributed antennas, or Wi-Fi.
Figure 10 shows an example of typical
spectrum allocation in such dense
traffic hotspots.
The indoor offload potential is quite
significant, since more than 80% of
global wireless data traffic will be
generated indoors and most of all new
smartphones and laptops are equipped
with Wi-Fi and cellular data
connectivity. The indoor offload will
connect users to the nearest
connectivity node, reducing
interference and transmission power,
increasing capacity and reducing
battery consumption.
Load-based traffic steering between
the macro, micro, pico clusters and
femto layers will be needed in order to
use the available spectrum efficiently.
Furthermore, automatic authentication
is needed for Wi-Fi offload to reach
its full potential, because manual
authentication will prevent some
users from going through the process
of registration.
Figure 11 shows an example of indoor
data offloading to either femto or Wi-Ficells in a macro and micro overlaid
network based on the spectrum
allocation in Figure 10. It shows that
fewer Wi-Fi nodes are needed to
provide the same performance as
femto nodes, since there is additional
spectrum available for Wi-Fi.
Indoor small cell ofoad
9Deployment strategies for Heterogeneous Networks
Spectrum allocation
21xx MHz 21xx MHz 21xx MHz 2400 MHz
5 MHz 5 MHz 5 MHz 20 MHz
Macro MacroOut-band
FemtoIndoor WiFi
Out-band
Micro
Figure 10. An example of 3G spectrum allocation including indoor offload.
30 Micros 30 Micros
+ 50 WiFi
30 Micros
+ 100 WiFi
30 Micros
+ 500 Femto
30 Micros
+ 1000 Femto
NetworkOutage%
Indoor
Outdoor
Macro-Micro-Indoor Deployment
Figure 11. Example of network performance in a traffic hot spot equipped with a macro network,
30 outdoor micro cells and further femto/Wi-Fi indoor offload.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
10/1610 Deployment strategies for Heterogeneous Networks
Indoor ofoad by femto cells
Femto cells were originally designed
for voice coverage but they also have
the potential to provide indoor data
offload. Femto cells for voice
coverage are expected to have limited
appeal in Europe, where customers
are reluctant to pay for network
coverage deficiencies. In the short
term, HSPA femto cells will dominate
the markets as LTE femto cells are
not required until LTE voice terminals
achieve mass market status.
The deployment of femto cells has
the same challenges as outdoor small
cell deployments. In-band deployment
provides the best performance for
limited spectrum or a low number
of femto cells, while femto cells
perform better deployed out-band
in large-scale deployments as outdoor
small cells.
The challenges of femto deployment
become even more pronounced
when a femto cell is configured with
a CSG identity. A user that is not part
of the CSG group will connect to
the micro of macro network and
experience/cause significant
interference problems as normal
mobility is overruled by the subscriber
group admissions.
The optimum performance will be
achieved by configuring all femto cells
as open subscriber groups (OSG).
However, femto cells provide excellent
voice coverage extensions and the
low transmission power and building
attenuation isolate the femto cells very
well from the macro cells.
Indoor ofoad by Distributed
Antenna Systems (DAS)
Distributed antennas inside stadiums,
office buildings or shopping malls
provide a good supplement to indoor
small cells. DAS provide very good
indoor coverage as the transmit power
is higher than that of femto cells and
Wi-Fi. However, DAS is more
expensive than femto cells and Wi-Fi
for providing large-scale data offload
and thus the recommendation is acombination of DAS for indoor
coverage and femto cells or Wi-Fi for
high data offload. Upgrading installed
DAS systems to LTE and/or new
frequency bands may limit MIMO
capabilities to keep costs low.
However, even non-MIMO-capable
LTE DAS deployments will provide
good indoor coverage and superior
date rates.
Indoor ofoad by Wi-Fi
Wi-Fi is an important local area
technology option for heterogeneous
networks, complementing mobile
technologies to improve performance
from the user perspective and offload
capacity. One of the criteria for Wi-Fi to
become a successful part of the mobile
network is the automatic attachment/
authentication procedure that enables
seamless Wi-Fi/mobile access and a
better user experience. Such automatic
attachment and authentication is
supported by Nokia Siemens Networks
Smart WLAN Connectivity solution,
called SWLANC.
The use of Wi-Fi technology is the
preferred means of offloading data from
macro cells for users at home or in the
office. Smartphones should use Wi-Fi
where possible. For public Wi-Fi
deployment, careful selection is crucial
for effective offload while providing the
best user experience. Outdoor Wi-Fi
deployment has limited potential where
mature macro networks are already
installed. It also requires careful planning
to limit interference sources from the
unlicensed spectrum. Furthermore,
many DSL lines are limited to less than
10 Mbps, which is slower than a typical
LTE macro cell.
The total Wi-Fi offload potential is ~40%
(0.8 x 0.8 x 0.8 x 0.8) assuming:
~80% of all traffic is generated
indoors.
~80% of total global handset traffic is
generated by smartphones.
~80% of all smartphone users have
Wi-Fi available.
~80% of all smartphone users
connect to the Wi-Fi (capture rate).
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
11/1611Deployment strategies for Heterogeneous Networks
Indoor coverage and capacity
with Pico Cluster (Fig.12)
Many indoor public or enterprise areas
are evolving into hot zones, and a new
approach that marries the benefits and
simplicity of Wi-Fi with robustness and
guaranteed QoE of 3GPP Micro/Picos
will be required.
Nokia Siemens Networks Flexi Zone is
such a solution and takes into account
the future need for very high celldensity with a Pico cluster of Multi-RAT
to leverage the installed Ethernet
network as backhaul. It aggregates
connected access points and local
break out to limit network impact and
provide local routing to enterprise LAN
servers if required. To achieve even
more cost-effective deployments,
SON principles are used to simplify
O&M. Interference management
techniques are used to ensure
scalability (low impact/fast deployment
of new Pico) and allow operators tocost effectively support the growth in
demand in indoor locations.
Recommendations
Indoor Wi-Fi deployment achieves
the lowest cost, lowest energy
consumption, and best network
performance in a high-traffic urban
environment. An out-band indoor femto
cell deployment requires more access
points to provide the same
performance, since it shares the
spectrum with the micro cell layer.
However, an indoor femto deployment
can provide significantly higher
average user equipment throughput
performance compared to indoor Wi-Fi
deployment, thanks to the higher
number of access points. DAS is a
good supplement to femto cells and
Wi-Fi for indoor coverage in large
indoor traffic hot spots. The summary
of the indoor offload recommendation
can be seen in Table 3.
Figure 12. Example Pico Cluster indoor deployment.
Ofoad Recommendations
technology
Wi-Fi Deployment for capacity enhancements, especially in high trafc
areas. Indoor deployment preferred to manage interference.
3G/4G Pico Deployment for coverage but focused on capacity in indoor public
Cluster in and private hot zones. High number of cells deployed with easy,
or out of band low impact and fast scalabil ity.
DAS Suitable to provide cost-efcient coverage in large-sized buildings.
Less cost-efcient for capacity-driven scenarios and small
buildings compared to femto cells/WiFi.
Femto Deployment for capacity enhancements, especially in high trafc
out-band areas. High number of cells deployed.
Femto Deployment for coverage and low/medium capacity
in-band enhancements. Large-scale deployment causes interference
with macro cells.
Table 3. Cost-efficient indoor offload recommendation in traffic hot spot areas.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
12/1612 Deployment strategies for Heterogeneous Networks
Total Cost of Ownership (TCO) is one
of the most important deciding factors
when choosing a network deployment
path. However, the TCO in each case
depends on the operators current
installed base, its spectrum situation
and user equipment penetration. The
different deployment paths have been
analyzed from a TCO perspective to
outline the key TCO trends.
The target of a TCO calculation is to
aggregate all the costs that occur over
the entire lifetime of a technical solution
(in this case complete network evolution
scenarios over 5 to 10 years) in a single
figure. The comparison of TCO values
for different network evolution scenarios
then allows the business value to
operators of the different deployment
options to be evaluated. The underlying
assumption for a fair comparison is that
the different network evolution scenarios
perform the same way and satisfy the
same traffic requirements. They are
then called ISO-performance scenarios.
Typically the TCO is calculated as the
sum of three components: capital
expenditure (CAPEX), implementation
expenditure (IMPEX) and operational
expenditure (OPEX). CAPEX and
IMPEX are one-off costs, while OPEX is
a recurring cost that must be specified
for a certain period of time. In this case
its the time taken for the network to
evolve. The deployment options already
described now have very different
characteristics regarding their cost
structure. These are:
Macro network extension
Multicarrier
If spectrum is available, adding more
carriers to already existing macro sites
provides easy and low-cost capacity
enhancements at macro sites. The main
cost is in CAPEX and IMPEX
(equipment and deployment), OPEX for
the base station increases only slightly
(electricity, O&M, backhaul). Howeverdedicating spectrum to micro cells can
provide an even bigger increase in
capacity. Therefore traffic growth and
Cost considerations
traffic hot spots play an important role
in any site evolution strategy.
Furthermore, refarming of spectrum is
a cost-efficient way to increase both
coverage and capacity. The most
cost-efficient approach is to deploy the
lower spectrum initially for coverage
and deploy the higher spectrum later
for macro or micro cells, depending
on the traffic density and spectrum
availability. LTE deployment should
be co-sited with HSPA sites to
minimize deployment costs. A new
site will have significantly higher cost
compared to the already existing
infrastructure at an existing site,
plus the site acquisition cost.
Sectorization
Sectorization in the vertical or
horizontal plane provides a simple yet
cost-efficient way to increase capacity
in the macro network. The main portion
of the cost is CAPEX and IMPEX
(equipment, antennas and deployment)
but OPEX is also raised owing to
higher electricity costs, backhaul and
additional site rent for new antennas.
Six sectorization is most efficient for
uniform traffic distribution and may
not be the best option in localized
areas of high traffic or in very dense
urban deployments where vertical
sectorization by Active Antenna
System (AAS) would be more
beneficial.
Tilt optimization
A very cost-efficient method for SINR
optimization and thereby increases
network capacity. Tilt optimization
should always be pursued before any
further optimizations.
C-RAN
Is expected to save money at macro
sites, since there is less equipment
on-site (with the baseband pooled at a
central location). Compared to legacy
base station deployments, additional
infrastructure such as shelters, power
supplies and so on can all be saved.But it also gives rise to additional costs
for building and operating the hotel
location for the centralized baseband
systems. C-RAN is only affordable if
operators have abundant legacy fiber
and the techniques are mature enough
for high-speed fiber connection
(~10Gbps) and advanced multi-cell joint
processing. OPEX may be lower thanks
to lower energy consumption.
Outdoor small cell
Micro/Pico cell deployment is a
cost-efficient way of increasing network
capacity and coverage. The realizationof outdoor small cells by micro base
stations means CAPEX for compact
micro equipment, but OPEX is very
significant for backhaul and site rental.
Also IMPEX for site acquisition and
deployment (including a power supply)
are relevant cost factors. Micro cells
should be deployed in dedicated
spectrum if available. In-band
deployment of micro cells may be more
expensive for high-traffic-density areas if
the spectrum is not already deployed on
the macro layer, since both layers wouldneed to be deployed. However, for
low/medium traffic-density-areas or
already-deployed macro spectrum,
in-band deployment is the preferred
cost solution.
Outdoor pico cluster
For outdoor hot zones, future
multi-RAT pico cluster solutions can
provide a very cost-effective approach
compared to other traditional solutions
and cell site splitting. For example,
Nokia Siemens Networks Flexi Zone
features a zone architecture that,
together with other innovations, helps
to reduce TCO by simplifying backhaul,
managing inter-intra layer interference
and limit the amount of spectrum
planning. This results in virtually
unlimited scalability, with limited impact
on the EPC and with local break out to
simplify installation and operations.
A pico cluster solution provides
up to 50% TCO benefit when addingcapacity compared to macro cell splitting
or the traditional micro/pico approach.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
13/1613Deployment strategies for Heterogeneous Networks
Indoor ofoading
Wi-Fi is always a low-cost supplement
to macro and micro/pico cell
deployments, since the spectrum is
freely available. However, the cost of
Wi-Fi depends on the particular
scenario with regard to backhaul and
site acquisition. Wi-Fi and femto cells
have very similar TCO performance,
with similar CAPEX and almost identical
installation and operational costs.
The decision on Wi-Fi versus femto
should be based on the spectrum
situation and a combined Wi-Fi/femto
deployment would provide the best
performance and operability in most
cases, since it would serve all user
equipment. Both Wi-Fi and femto cells
offer big benefits for residential and
office installations, while public
installations should be based on the
traffic density and the available
spectrum. The underlying assumption
for residential and office scenarios is
that backhaul at the deployment
locations can be reused without
incurring site costs. The cost in offices
is assumed to be about four or five
times higher than the cost in a
residential scenario.
Future Multi-RAT Pico cluster solutions
such as Nokia Siemens Networks Flexi
Zone, will provide a best-of-both-
worlds approach with Wi-Fi and HSPA/
LTE support, and a cost effective and
scalable solution for indoor coverage
and capacity deployments.
Recommendations
The financial impact of the
deployment options mentioned was
investigated in different real-network
scenarios with operators. Although
the conditions in different networks
vary quite significantly, some general
results and recommendation could
be derived. The preferred
deployment solution from both a
performance and cost perspective is
a combination of a perfect macro cell
deployment for coverage and high
mobility users, outdoor micro/pico
cell deployment for dense traffic
areas and indoor offload for
extremely dense traffic areas with
low mobility. The recommendations
are summarized in Figure 13.
Macro
Extension
Offload to
Indoor
C-RAN
Cost Savings
Can provide Opex benefits when compared to
legacy RAN and assuming extensive fibre. But
modern distributed RAN is more profitable today.
Wi-Fi Offload
Enhanced Capacity
at lower cost
Provides significant outage and capacity enhance-
ments especially in high traffic areas. Depending on
the scenario the cost for Wi -Fi is very low.
Multicarrier
Enhanced
Capacity, High
Profitability
Provides easy and low cost capacity
enhancement at macro site. However
dedicating spectrum to micro can provide even
higher capacity increase.
Pico Cluster
Enhanced Capacity
at lower cost
Provides significant outage and capacity
enhancements especially in high traffic areas.
Provides cost efficient deployment.
6-Sectorization
Enhanced
Capacity, High
Profitability
In general very efficient for capacity increase but
not a viable option if high traffic ares are very
localized or in very dense urban deployments.
Femto
Enhanced Capacity
at lower cost
Provides outage and coverage/capacity
enhancements. Large deployment density causes
interference challenges with macro.
Tilt Optimization
Enhanced
Coverage
Though impact of antenna tilting was overestimated
in statistical propagation models it is still a cost
efficient method of SINR optimization in general.
DAS
Enhanced Coverage
at lower cost
Suitable to provide cost-efficient coverage in large
-sized buildings. Less cost-efficient for capacity
driven scenarios and small buildings.
Outdoor
Small Cells
Micro
Enhanced
Coverage and
Capacity
Cost efficient means to increase network capacity
and coverage. Inband deployment if spectrum is
limited otherwise outband deployment.
Pico Cluster
Enhanced
Coverage and
Capacity
Cost efficient means to increase network capacity
and coverage.
Fully recommended
Recommended except certain scenarios
Partly recommended
Figure 13. Deployment cost considerations.
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
14/16
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
15/1615Deployment strategies for Heterogeneous Networks
Abbreviations
3GPP Third Generation partnership Project
AAS Active Antenna Systems
AWS Advanced Wireless Services
CAPEX Capital Expenditure
C-RAN Cloud RAN
CSG Closed Subscriber Group
DAS Distributed Antenna Systems
DL Downlink
DSL Digital Subscriber lines
EPC Evolved Packet Core
FACH Forward Access Channel
HetNets Heterogeneous Networks
HSPA High Speed Package Access
IMPEX Implementation expenditure
LTE Long Term Evolution
M2M Machine to Machine
MBB Mobile Broadband
MIMO Multiple input multiple output
NLOS Non line of Sight
OPEX Operational Expenditure
OSG Open Subscriber Group
QoE Quality of Experience
RACH Random Access Channel
RAN Radio Access Network
RAT Radio Access Technology
SINR Signal to Interference and Noise Ratio
SON Self Organizing Networks
TCO Total cost of Ownership
UL Uplink
Wi-Fi 802.11xx
-
8/11/2019 20120531 Nokia Siemens Networks Deployment Strategies for Heterogeneous Networks Final
16/16
Copyright 2012 Nokia Siemens Networks.All rights reserved.
A license is hereby granted to download and print acopy of this document for personal use only. No otherlicense to any other intellectual property rights is grantedherein. Unless expressly permitted herein, reproduction,transfer, distribution or storage of part or all of thecontents in any form without the prior written permission
of Nokia Siemens Networks is prohibited.
The content of this document is provided AS IS,without warranties of any kind with regards its accuracyor reliability, and specifically excluding all implied
warranties, for example of merchantability, fitness forpurpose, title and non-infringement. In no event shallNokia Siemens Networks be liable for any special,indirect or consequential damages, or any damageswhatsoever resulting form loss of use, data or profits,arising out of or in connection with the use of thedocument. Nokia Siemens Networks reserves the rightto revise the document or withdraw it at any time withoutprior notice.
Nokia is a registered trademark of Nokia Corporation,Siemens is a registered trademark of Siemens AG.The wave logo is a trademark of Nokia SiemensNetworks Oy. Other company and product namesmentioned in this document may be trademarks of theirrespective owners, and they are mentioned foridentification purposes only.
Nokia Siemens Networks Corporation
P.O. Box.1
FI-020022 NOKIA SIEMENS NETWORKS
Finland
Visiting address
Karaportti 3, ESPOO, Finland
Switchboard +358 71 400 4000