1. Charting the Course
for Mobile Broadband
Heading Towards High-Performance
All-IP with LTE/SAE
2. Executive Summary
Nokia Siemens Networks expects five With a view to taking the next step up
billion people to be connected to the the evolutionary ladder beyond HSPA,
Contents
web and a 100-fold traffic increase in 3GPP Rel8 has standardized a
02 Executive Summary the networks by 2015. Wireless access technology called Long Term Evolution/
to the Internet will be in step with System Architecture Evolution (LTE/
03 Background
wireline access. Access via mobile SAE). It is designed to
04 Market drivers and expectations
phone supporting enhanced data
05 User benefits applications will complement notebook • Make the most of scarce spectrum
06 Operator expectations based usage. Wireless networks will be resources: Deployable in paired and
used to extend broadband penetration
08 System approach unpaired spectrum allocations with
beyond the reach of wireline networks. bandwidths ranging from 1.4 MHz
09 Standardization of the LTE air
More and more user communities will to 20 MHz, LTE/SAE offers up to
interface and enhanced packet enjoy multimedia services, driving total four times the spectral efficiency
system bandwidth demand. This affords of HSDPA Release 6
mobile network operators a business
10 Optimizing total value of • Afford users an experience on
opportunity they can capitalize on by par with today’s best residential
ownership with Nokia Siemens
improving their networks’ performance broadband access: LTE/SAE
Networks´ LTE/SAE and efficiency. delivers peak user data rates
14 Conclusions ranging up to 173 Mbps and
15 Abbreviations reduces latency to as low as 10 ms
• Leverage flat all-IP network
15 References
architecture and a new air interface
to significantly cut per-Mbyte costs,
with later product innovations
improving performance even further:
For instance a 4x4 Multiple Input/
Multiple Output (MIMO) scheme
will boost downlink data rates up
to 326 Mbps
Nokia Siemens Networks takes a cost-
effective approach to introducing LTE/
SAE, enabling GSM-/WCDMA-, CDMA-,
and greenfield network operators to
grow their business and margins in
the fast-approaching era of ubiquitous
mobile broadband.
2 Network Evolution LTE/SAE
3. Background
The Internet has changed many Mobile broadband users will expect
people’s lives in the last decade. services, data rates, VoIP and multimedia
Services delivered across the web capabilities similar to those enjoyed
now supplant many offline processes. by fixed broadband users today, at
The Internet has become a major affordable prices. This is why NGMN
delivery platform for text, music, video, Ltd., a group of globally active mobile
and other multimedia content. All this operators determined to match DSL
has spurred broadband’s growth. With offerings’ performance and cost, has
broadband adoption outpacing cellular raised the bar for the next generation
voice, Nokia Siemens Networks predicts of mobile networks (NGMN) and
that five billion people will enjoy Internet described their requirements in a
access by 2015 and traffic in the white paper [1]. Seeking to satisfy
networks will increase 100-fold. these demands, Nokia Siemens
What’s more, mobile broadband is Networks and its parent companies
tracing mobile telephony’s trajectory, participated in the Long Term Evolution
becoming a widespread service to be (LTE) and System Architecture Evolution
enjoyed by the user anywhere, anytime. (SAE) studies conducted by the Third
Generation Partnership Project (3GPP).
More and more people are embracing LTE/SAE aims to improve performance
mobile broadband and enjoying data- and cost-efficiency with a more efficient
heavy video and other multimedia air interface, more flexible use of radio
content. This coincidental development spectrum, and flat, packet based
presents a promising business network architecture. The ultimate
opportunity for network operators, goal is to enable wireless broadband
who responded by launching HSDPA communication commensurate with
and flat rates in 2006, attracting many DSL in fixed networks.
business users. And while this user
segment may be small compared to The study phase of 3GPP work on
the huge consumer market, overall LTE and SAE ended in mid-2006,
mobile data traffic grew up to 400% transitioning to the specification phase
within 6 months after service for the new radio access system (LTE)
introduction in many networks. and the enhanced packet-based core
network (SAE).
3GPP plans to complete the first set
of specifications by the end of 2008,
enabling friendly user trials in 2009
and the first commercial network
rollouts at the beginning of 2010.
Network Evolution LTE/SAE 3
4. Market drivers and expectations
Evolving user services
Video streaming Video conferencing Real-
time
New services will center on data and
> 5 Mb/s
gaming
m2m:
Audio/video
multimedia communication alongside robot security;
download
video broadcast
or within the context of voice.
Figure 1 shows some of these services
Bandwidth
1 Mb/s
Mobile
and their typical bandwidth and network office/e-mail
FTP Multiplayer
Interactive
latency requirements. Services expected games
remote Growth drivers
to become major growth drivers are games
MMS, Video telephony
web-browsing Audio streaming
highlighted. While voice remains the
< 64kb/s
SMS
most popular application for large user Voice telephony
segments, several distinct trends will m2m: remote control
Voice mail
influence mobile communications in the Network
> 1 sec 200 ms 100 ms 20 ms
Latency
years ahead:
Source: IST-2003-507581 WINNER, D1.3 version 1.0, Final usage scenarios. 30/06/2005;
„Parameters for Tele-traffic Characterization in enhanced UMTS2“, University of Beira,
Portugal, 2003
• Common, access-independent
Internet applications will replace
silos for mobile and residential Figure 1: Latency and bandwith requirements for various services
applications
Rising traffic, falling tariffs
• Web2.0 applications empower users The key enabler for these trends to
to participate in communities, and materialize in mobile communications is
will generate content and interact in user gratification, which will depend on:
Overall traffic (voice and data) in mobile
virtual worlds
networks is expected to grow fast.
• Streaming services that deliver • The network’s capacity to support
Data traffic in some European HSPA
individual video content on demand high peak user data rates and high
networks is edging towards exponential
and mobile TV on demand are average data throughput rates
growth. Analysts predict average price
emerging as a favored application • Low user data plane’s and signalling
per MB will decline as voice and
• Mobile, interactive remote channels’ response time, or latency
non-voice services drive traffic growth.
gaming and real-time gaming • Guaranteed radio coverage
A strong trend towards flat-rate pricing
will undoubtedly become a major ensuring full use of services with
is already sweeping the market. Data
industry in its own right acceptable throughput up to the
and multimedia service offerings with
• Mobile office comprising smart cell’s edge
attractive service packages and flat
phones, notebooks, ubiquitous • Service continuity between
rates are key business differentiators.
broadband access and advanced access networks
Voice services, in turn, are fast becoming
security solutions will free business • Competitive prices, with many users
a commodity, and price pressure is
users from their office desk. favoring flat-rate fees for reasons of
bound to rise. This compels operators
transparency and cost control
to respond by offering voice service by
migrating it to packet based VoIP. And
As users discover personal mobile
as flat rates become more popular,
services on par with household-centric
Traffic volume Network cost
operators will have to cut the per MB
(existing technologies) services, they are sure to take advantage
cost of sending data across the network.
of mobile operators’ great strength –
Fair usage policies need to be applied
mobility. The key is to satisfy users’
in order to prevent bandwidth-greedy
expectations of access whenever
Revenue
applications, especially peer-to-peer
and wherever they want it.
Profitability
file sharing, from overloading the
Network cost
network.
(LTE)
Time
Figure 2 shows that in Voice dominated networks the revenue was about
Voice Data
proportional with the traffic volume increase. In Data dominated networks
dominated dominated
offering flat rate or fair usage flat rate tariffs the traffic volume is expected to
rise exponentially; but the revenues will only slightly increase, stay constant,
Price per MByte has to be reduced to remain profitable
or in some markets even decline. In order to stay profitable in the long term
operators are forced to introduce new network technologies offering much lower
costs, which are decoupled from the traffic volume to the greatest possible extent.
Figure 2: Traffic increase requires low cost/bit technologies
4 Network Evolution LTE/SAE
5. User benefits
Advances in technology
Optimizing digital signal processing
algorithms and advances in antenna
technologies will push the air interface’s
spectral efficiency ever closer to its While many consumers have no Figure 3 compares LTE/SAE’s peak
theoretical limits. particular interest in technology, they data rates, average cell throughput,
do expect unimpeded access to the VoIP capacity and latency with earlier
Improved IP transport (pervasive Internet and personalized services, WCDMA/HSPA releases. On the
Gbit Ethernet) and QoS assurance at anytime and in any place. physical layer, LTE/SAE with 2x2
technologies boost packet-centric MIMO delivers peak downlink data
networks’ data and voice performance, Today’s residential broadband access rates ranging up to about 173 Mbps,
efficiency and carrier-grade reliability. shapes consumers’ expectations of and even 326 Mpbs with 4x4 MIMO.
Together with advances in IP Internet access and their perceptions
integration in network equipment and of network performance. Coexistence, interoperability, roaming,
implementation of spectrally efficient and handover between LTE/SAE and
VoIP techniques, this all will soon make This perceived network performance, existing 2G/3G networks and services
the all-IP vision a reality. LTE/SAE in turn, is formed by a blend of the are inherent design goals, so full mobility
enables operators to implement all peak user data rate, average user support is given from day one.
services on a single IP-centric, purely throughput, cell throughput, signaling
packet based network. This will make delays, and user data latency. One
IP applications as genuinely mobile of the keys to differentiating mobile
as voice is in today’s mobile networks. products is boosting perceived mobile
These advances, alongside a simplified broadband performance.
architecture, will also reduce
operational expenditures and,
consequently the network’s lifecycle
costs.
Average cell throughput
(marco cell, 2x20MHz or equivalent) *
Maximum peak data rate *
2x20MHz 1 carrier,
70
350 2x20MHz
Downlink Downlink
60
300 Uplink Uplink
U
50
250 1 carrier,
2x20MHz
Mbps
2x20MHz
200 40
Mbps/cell
4 carriers,
each 2x5MHz
30
150
4 carriers,
20
100 each 2x5MHz
2x5MHz
10
50
2x5MHz
0 0
HSPA R6 HSPAevo LTE LTE HSPA R6 HSPAevo LTE LTE
(2x2 MIMO (2x2 MIMO/ (4x4 MIMO/ Rel8 (2x2/1x2 (4x4/1x4
+ 64QAM) 16 QAM) 64 QAM) (MIMO) MIMO)
Latency (Roundtrip delay) ** VoIP capacity *
80
70
GSM/EDGE
Downlink
60
Uplink
HSPA Rel6
Calls/MHz/Cell
50
40
HSPAevo
(Rel 8) 30
20
min. max.
LTE
10
20
0 40 60 80 100 120 140 160 180 200 ms
0
DSL (~ 20 - 50 ms, depending on operator) HSPA R6 LTE FDD
* LTE values according to Nokia and Nokia Siemens Networks ** Server near RAN
simulations for NGMN performance evaluation report V1.3
(marco cell, full buffer, 500m ISD, pedestrian speed)
Figure 3: Comparison of throughput (maximum, typical) and latency: LTE shows excellent performance
Network Evolution LTE/SAE 5
6. Operator expectations
Major operators formulated their
Competitive Network Cost
Superior User Experience
1 2
expectations for the LTE air interface
performance in a whitepaper [1]:
Peak throughput Latency Cost per MByte
~ 50% • High spectral efficiency (3-4 times
that of HSPA Rel 6 in DL and 2-3
Factor 10 Factor 2-3
times that of HSPA Rel 6 in UL) and
> 70%
cell edge performance
• High peak data rate >100 Mbps in
DL and >50 Mbps in UL for 20 MHz
HSPA LTE HSPA LTE UMTS HSPA I-HSPA LTE
bandwidth
Figure 4: Key building blocks of operator success
• Low latency
(round trip delays below 20 ms)
• Flexible and scalable bandwidth
The user benefits outlined above • Gearing up to re-farm frequency deployable in all IMT2000 spectrum
translate into revenue potential for the bands such as GSM and possibly (450 MHz up to 2.6 GHz) both for
operator. To tap this potential and turn operating in lower frequency bands paired (FDD) and unpaired (TDD)
into profits, operators must optimize to exploit spectrum options and frequency bands
both revenues and costs. And the need to maximize coverage at lower
to improve cost efficiency increases as investment, especially in rural
Network complexity
data traffic rises and per-MB prices drop. areas with lower traffic density.
Re-farming GSM and CDMA
requires a solution suitable for small
Air interface performance The consensus is that the complexity
bandwidth allocations, as operators of system architectures and diversity
and flexibility
probably can not release much of protocols are major cost drivers for
spectrum from the beginning due to networks and terminals. This complexity
Driving down cost per MB entails legacy GSM or CDMA traffic. and diversity can be mastered by:
improving the air interface’s efficiency • Reducing the latency of user data
and applicability by: transmitted over the air interface in • Simplifying the network architecture
order to reduce the overall download with a flat hierarchy and much fewer
• Increasing spectrum efficiency times of Web pages and thus protocol conversions (or content
and cell edge bit rates, and flexibly improve the overall throughput on mappings)
allocating bandwidth by making the the application level • Introducing open, streamlined
most of available spectrum • Supporting fast service access to interfaces and reducing protocol
• Operating in the 3G spectrum – if minimize system load and maximize options
necessary, alongside a 3G system the number of simultaneously • Employing IP-centric communication,
– and in soon-to-be assigned new served users equipment and VoIP throughout the
spectrum
core and radio networks
• Extensively employing low-cost
backhauling such as carrier-grade
Ethernet rather than E1/T1 based
leased lines
• Supporting self-configuring and self-
optimizing network technologies to
reduce installation and management
costs
6 Network Evolution LTE/SAE
7. • Deployment of LTE on existing
Service provisioning Operators expect that this huge
sites and sharing of common
ecosystem can be leveraged for
infrastructure (e.g. antenna masts;
LTE/SAE as most terminals will
Recent surveys indicate that user site infrastructure like power supply,
be UMTS/LTE or GSM/UMTS/LTE
expectations are difficult to predict air conditioning, and security
multimode terminals offering cost
over the long-term. In reality, analysts equipment; feeder cables and even
advantages from the common terminal
expect services to become a short-term antennas)
platform and production quantities.
business offering. This means operators • Sharing of backhauling equipment
need to consider: between LTE/SAE and existing
Interworking with and
network technologies provided
• The means to create highly at the same site migration from non-3GPP
personalized services, and deliver • Common network management
radio access systems
every type of service, including platforms
end-user self-provisioning • Depending on the implementation
• Individual support for every type of Optimal interworking with existing
of existing network elements, the
access based on a common service GSM/WCDMA networks, including
upgradability of their HW platforms to
control and provisioning platform service continuity when roaming
LTE/SAE or even a sharing of parts
• An improved user experience between LTE/SAE and such networks,
of the network element HW platform
for every service offering and is a natural expectation of operators
with existing 2G/3G technologies
diversified offerings, including and inherent design goal for the LTE/
offers opportunities for CAPEX and
flexible service bundling across SAE standard. However, operators of
OPEX savings.
all breeds of access non-3GPP radio access systems, like
• Simple and transparent billing CDMA, also expect an easy evolution
Size of the ecosystem
procedures which foster of their networks to LTE/SAE, in order
subscriber loyalty to benefit from the scale of the 3GPP
Mobile systems based on 3GPP ecosystem representing more than
standards represent with a market 85% market share in the mobile industry.
Asset reuse
share of more than 85% by far the 3GPP acknowledged this need by
greatest ecosystem in the mobile specifying an improved interworking
When introducing new network industry, which provides enormous between LTE/SAE and non-3GPP radio
technologies, operators expect that their cost advantages to operators and access systems. In particular the
existing investment will be protected end users: standard supports seamless mobility
and that deployed infrastructure can be and handover between LTE and
re-used to the greatest possible extend. • A huge variety of different terminals, CDMA2000.
The main focus is thereby directed to starting from simple and cheap
topics representing a major part of voice only terminals up to real
operators’ total cost of ownership, multimedia terminals
such as: • Cost benefits for terminals and
network infrastructure products due
to the huge quantity of produced
products and the amount of different
vendors offering such products.
Network Evolution LTE/SAE 7
8. System approach
Simplified network High-performance
In light of the efforts to standardize LTE/
SAE underway, 3GPP defined the air architecture air interface
interface, network architecture, and
system interfaces. Figure 5 shows
Today’s WCDMA core network The LTE air interface will differ markedly
an LTE/SAE network’s high-level
architecture for the PS domain from legacy technology. Figure 6
architecture. 3GPP standardized a
comprises SGSN and GGSN. summarizes the technologies applied
packet-based network architecture with
The radio network architecture at the LTE air interface.
fully IP-based transmission. LTE/SAE
comprises NodeB and RNC.
will not entail a circuit-switched domain
Advanced applied Orthogonal
anymore; that is, VoIP will serve to
LTE/SAE architecture is streamlined to Frequency Division Multiplexing
implement voice. The IP backbone
optimize network performance, maximize (OFDM) technologies achieve
network will support guaranteed QoS
data throughput, and minimize latency. performance and savings goals
on demand with a very simplified, but
Rather than four nodes in the user data based on low total cost of ownership.
backward compatible QoS concept.
plane (Node B, RNC, SGSN, GGSN),
The goal is to use carrier-grade Ethernet
the LTE architecture will comprise a far Many sub-carriers may be allocated
where possible; in particular to connect
simpler configuration of just eNode B according to carrier bandwidth available
the eNode B, the LTE’s base station.
and the SAE Gateway (SAE GW). The in the downlink. The uplink employs
SAE GW consists of two logical user a single carrier FDMA technology
plane entities, the Serving Gateway (SC-FDMA) to preclude high peak-
Service Control and Data Bases and PDN Gateway. The Serving Gateway to-average power ratios, thereby
provides the user plane anchor that streamlining the RF design and
manages mobility between GSM and extending the battery life of the
IMS PCRF HSS/AAA
WCDMA/HSPA access systems terminals.
standardized according to LTE and
Access Core Switching & Transport
3GPP. The PDN Gateway interworks Advanced scheduling in the time and
with the Internet or intranets and the frequency domain, MIMO antenna
user plane anchor to enable mobility technology, Hybrid Automatic Repeat
MME
between LTE and non-3GPP based Request (HARQ) and higher order
SAE
access systems such as CDMA modulation (up to 64 QAM), combined
GW
Internet
networks. It also provides policy control with fast link adaptation methods and
Serving GW PDN (HA)
eNode B
and charging functions. For roaming a short Transmit Time Interval (TTI)
purposes, the Serving Gateway resides of 1 ms, maximize spectral efficiency.
in the visited network, and the PDN
Gateway in the home network. In principle, operators need not acquire
Figure 5: LTE/SAE target architecture
new spectrum. The LTE air interface is
The interface between Serving GW designed to operate in the same spectrum
and PDN Gateway is standardized as and in parallel with the legacy
to support roaming scenarios; but both WCDMA/HSPA air interface, for example
functionalities can be implemented on on a separate carrier. The system’s
the same physical platform. flexible spectrum allocation (including
scalable bandwidth) allows carriers to
The signaling protocols of the control be spread across any suitable spectrum
plane will be handled by the Mobility licensed for 2G or 3G operation.
Management Entity (MME).
Deployable in spectrum bands with
Because the access network operates bandwidths of 1.4, 3, 5, 10, 15, and
without a central controller (BSC, RNC), 20 MHz, LTE offers unique spectrum
base stations (eNode B) interconnect flexibility. The small 1.4 and 3.0 MHz
via standardized interfaces to exchange bandwidths are optimized for GSM and
control and user information. They also CDMA re-farming, where operators
connect directly to the core network. might not initially be able to free up
more bandwidth.
This approach entails fewer interfaces
and minimal complexity caused by LTE air interface is designed for
protocol conversion and content deployment in paired (FDD Mode) and
mapping. unpaired (TDD mode) spectrum bands.
The initial deployments outside China
are expected to be for FDD mode in
paired spectrum.
8 Network Evolution LTE/SAE
9. 64 QAM Fast Link Adaptation
scalable Hybrid ARQ
Modulation
1 2
NACK ACK
DL: OFDMA UL: SC-FDMA 1
Combined Available bandwidth
decoding
Sub-carriers
2
Rx Buffer
Short TTI =1 ms ...
Transmission time interval
OFDM
symbols
Frequency
...
Guard
RX
TX intervals
Advanced Scheduling Time
MIMO Time & Frequency
Channel RX
TX (Frequency Selective Scheduling)
Figure 6: The beauties of LTE
Channel only changes amplitude and phase of sub-carriers
Standardization of the
LTE air interface and
enhanced packet system
3GPP (3rd Generation Partnership Now 3GPP working groups are working
program) is standardizing the LTE/SAE hard on finishing all protocol (stage 3)
system for their Release 8. and performance specifications.
Their RAN working groups started LTE/ It is expected that all LTE/SAE
SAE standardization in December 2004 specifications will be finished by
with a feasibility study for an evolved end of 2008, the specification of the
UTRAN and the System Architecture physical layer of the air interface
Evolution (SAE) for the all IP based, (forming the basis of the chip design)
flat core network architecture. This for the FDD mode of operation by
was transformed into the Work Item mid-2008 already.
phase in June 2006. In December
2007 all LTE functional specifications
(stage 2) were finished. SAE functional
specifications reached major milestones,
both for interworking to 3GPP and
CDMA networks.
Network Evolution LTE/SAE 9
10. Optimizing total value of
ownership with Nokia
Siemens Networks´ LTE/SAE
LTE/SAE will provide a mobile multimedia For many years, Nokia Siemens
network that delivers broadband wireless Networks and its parent companies
services with fixed-line quality and the have driven radio access and network
cost efficiency of IP technologies. Nokia technology innovation by:
Siemens Networks leverages leading
architectural and systems expertise to • Participating in international
allow operators to seamlessly evolve research programs
their networks to LTE/SAE. • Pursuing many joint research
activities in these areas with diverse
Nokia Siemens Networks has ample industry and academic partners
experience in implementing and • Driving 3GPP’s efforts to
upgrading complex system architectures. standardize LTE/SAE
The company is committed to enabling
smooth migration, and is preparing its The world’s first live demonstrations of
products to accommodate LTE/SAE the LTE air interface’s capabilities at
technology. The track record of Nokia the 3G World Congress in Hong Kong
Siemens Networks in efficient system in December 2006 and 3GSM World
migration includes: Congress in Barcelona in February
2007 underscore Nokia Siemens
• Easy introduction of EDGE Networks’ leadership in LTE/SAE.
without system downtime In this demonstration (refer to figure 7)
• HSPA (HSDPA and HSUPA), where a High Definition Television (HDTV)
a software download upgrades the video was sent with a peak data rate of
entire installed base 160 Mbps over an air interface based on
• Combined 2G/3G networks enabling the preliminary LTE specifications and
smooth migration from 2G to 3G and handed over in real time to an HSPDA
ensuring cost-efficient operations air interface.
• The SGSN and GGSN for the packet
core, which today can handle both
2G and 3G traffic
Multimode UE Access Core Services
MIMO
Video application
IMS
eNode B IPv6 (IMS-controlled
(control node and AS)
video supervision)
Access Gateway
(packet core)
Video application
IMS client Video application
HSPA luB
(Real-time video
Node B IPv6
streaming – HDTV)
Figure 7: Nokia Siemens Networks` LTE demonstrator: First live NGMN air interface
– with applications and interworking with legacy 3G system – service continuity in one equipment
10 Network Evolution LTE/SAE
11. Further Nokia Siemens Networks initiated
together with Nokia and six other vendors Nokia Siemens Networks drives LSTI.
Schedule & Program Office Activities:
and operators the so-called LTE-SAE
Trial Initiative (LSTI). The goal is to early
2007 2010
2008 2009
demonstrate the capabilities of LTE/
SAE through performing a series of Test of OFDM Air Interface
Proof of Concept
joint tests including radio transmission
performance tests, early interoperability Test of basic functions
tests, field tests and full customer trials
Interoperability
IODT
(refer to figure 8). By giving early feed-
back about the LTE-SAE
IOT
performance and interoperability to
standardization and industry, the time Trials
Friendly customer trials
for commercial product availability is
expected to be significantly reduced.
PR
In the meantime further operators, Public Relation work
terminal- and chipset vendors joined
the group, which is open to any
organisation that is committed to
actively contribute to above goals. Figure 8: LSTI program and schedule
The first proof of concept tests on An operator’s strategy for gaining the
physical layer performance of the LTE competitive edge in mobile broadband
eNB Site: HHI Building
air interface (performed independently builds on three fundamental insights:
by several companies) where already
finished by the end of 2007 and • The key to sustaining fast subscriber
successfully demonstrated that the growth is being part of a large
physical layer of the LTE air interface ecosystem that accommodates
300 m
specifications can be implemented and many different – as well as the
fulfils the performance expectations. latest – user devices, as is evident
from the recent churn from
In December 2007 Nokia Siemens CDMA to GSM networks. GSM/
Networks demonstrated LTE in a multi- WCDMA is by far the largest
user field trial under realistic urban mobile communications ecosystem
MIMO/SIMO
deployment scenarios in the center of worldwide.
120 Mbps
Germany’s capital Berlin, reaching with • Once traffic attains critical volume,
600 m
100 Mbps
a 2x2 MIMO antenna system peak there is only one way to achieve
80 Mbps
data rates of up to 173 Mbps and still cost-efficient scale network capacity
60 Mbps
more than 100 Megabits per second – via flat network architecture and
40 Mbps over distances of several hundred Ethernet based transport network.
meters (refer to figure 9). This trial Until now, fixed broadband networks
20 Mbps
900 m
DLink also successfully demonstrated that provided the blueprint; now I-HSPA
future LTE networks can run on (Internet-HSPA) introduces flat
existing base station sites. architecture to cellular networks.
Figure 9: Nokia Siemens Networks multi-user LTE field trial in the
centre of Berlin • Ubiquitous mobile broadband
demands optimum use of scarce
spectrum resources, cost-efficient
networks, and high network
performance as perceived by users.
Network Evolution LTE/SAE 11
12. • Operators running 2G networks
Nokia Siemens Networks is committed Nokia Siemens Networks provides all
(GSM/GPRS) can introduce LTE/
to providing a smooth evolutionary products of a mobile network end-to-end
SAE directly or via one of the above
path for every operator, following a solution using innovative technologies
WCDMA/HSPA paths, depending
roadmap that factors each operator’s and future-proof platforms:
on their timetables for introducing
installed base and strategy into the
mobile broadband services and
equation (see figure 10). • Nokia Siemens Networks designs
the spectrum they have available. innovative base stations enabling
Because LTE supports bands as
• 3G operators who have deployed operators to flexibly upgrade to future
small as 1.4 MHz, spectrum may be
I-HSPA have flat network radio standards while reusing legacy
re-farmed smoothly and gradually
architecture similar to LTE/SAE in modules and without adding to the
from GSM to LTE.
place, and can thus cost-efficiently footprint. This affords operators total
• CDMA operators can introduce LTE/
introduce LTE/SAE. investment protection. One example
SAE networks directly or follow one
• 3G operators with a deployed is the innovative Flexi-Multimode
of the above paths. GSM/EDGE
WCDMA/HSPA network can BTS platform, designed to support
may be a good choice for strategies
migrate directly to LTE/SAE. different radio standards and being
more immediately focused on voice
Migrating to the flat network SW upgradable to LTE. It is modular,
centric business. The same applies
architecture of Internet High with the flexibility required to upgrade a
to Greenfield operators. Operators
Speed Packet Access (I-HSPA) 2G/3G site to support LTE. To this end,
opting to take the I-HSPA path
may also be beneficial because it shares LTE-ready equipment in the
can capitalize on the ecosystem
it accommodates LTE/SAE’s flat RF chain – the antenna, the feeder, as
of HSPA terminals, benefit from
IP-based network architecture while well as – given deployment in the same
the flat architecture today, and
supporting legacy WCDMA/HSPA spectrum – RF modules. Different radio
quickly optimize mobile broadband
handsets. The operator can thus standards supported at the same site
performance.
enjoy the transport and network can also share the backhaul system.
• Operators with TD-SCDMA
scaling benefits immediately and Dedicated but identical hardware
networks, which are currently
easily upgrade the network to LTE/ baseband and control modules serve
deployed in China only, will probably
SAE later. to run the different radio standards
migrate directly to LTE, preferably smoothly and independently. All this
using the TDD mode of LTE. minimizes the operator’s spare parts
inventory, logistics costs and
installation efforts.
GSM/WCDMA Enabling flat broadband architecture
handset base
LTE
I-HSPA
WCDMA/
HSPA
GSM/
TD-SCDMA
(E)GPRS
CDMA
Figure 10: The architectural evolution of existing 2G/3G networks to LTE
12 Network Evolution LTE/SAE
13. RAN Evolved Packet Core (EPC)
GSM
SGSN/MME
PCRF
BSC
BTS
SGSN SAE Gateway
WCDMA
Serving Content
PDN
RNC
and service
GW GW
NodeB networks
LTE
Control plane
HSS
MME User plane
eNodeB
Figure 11: 3GPP Rel8 LTE/SAE network architecture (simplified)
• PS domain network nodes connect The Nokia Siemens Networks’ LTE/
multiple access technologies and SAE solution enables operators to cost-
interfaces to service control and efficiently introduce and run LTE/SAE:
database functions. The SGSN and
GGSN will evolve to serve as the • No additional site preparations
SAE network’s MME and SAE GW. required: Nokia Siemens Networks’
Operators may also install SGSN- BTS platforms enable LTE radios to
and MME-functions on separate be easily added to legacy equipment
physical nodes without enlarging the footprint
(refer to figure 11). • Flexible approach: If necessary,
• A powerful means of migrating operators may run LTE alongside
all services, the IP Multimedia GSM/EDGE, WCDMA/HSPA or
Subsystem (IMS), provides other radio access systems such
common service control. as CDMA, WLAN or WiMAX
• The Nokia Siemens Networks’ • Painless migration: LTE/SAE fully
network management system supports security, roaming, QoS,
supports common operational and similar features
procedures. • Reusable infrastructure: Current
2G/3G applications may be used
These products feature high again in LTE
performance technologies that
configure and adapt flexibly to suit
deployment requirements. They
also bring to the table all the benefits
of reliable carrier-grade systems.
This approach ensures cost-effective
network migration, early system
availability and stability, and protects
investments in the overall LTE/SAE
solution.
Network Evolution LTE/SAE 13
14. Conclusions
The evolving mobile broadband business LTE/SAE charts a natural evolutionary
opportunity calls for high performance course for 2G/3G operators because
all-IP mobile broadband networks. it offers:
The motivations, requirements and the
solution based on the LTE/SAE standard • Investment protection by reusing
have been discussed. Several user sites and network elements to the
studies lead to the conclusion that maximum
traffic in mobile networks will snowball • A superior user experience
in the years ahead. The driving forces enhanced by high throughput and
behind this growth are: low latency, offering rich potential
for subscriber uptake
• Broadband Internet access offering • Low cost per MB courtesy of a flat,
a DSL-like user experience IP-based network architecture and
• On demand video content and high spectral efficiency, enabling
Web2.0 applications operators to cost-efficiently
• Fixed voice substitution introduce flat rates
• Service convergence across • Scalable bandwidth ranging
multiple access technologies from 1.4 up to 20 MHz, enabling
operators to exploit lower and
While WCDMA/HSPA has made other economically-attractive
significant strides towards efficient frequency bands where relatively
mobile data and multimedia information little spectrum is available, achieving
exchange, LTE/SAE will provide nationwide coverage at far lower
extended network performance and costs
reduced cost per MB that are able
to deliver on the promise of future As an industry pacemaker, Nokia
broadband mobile wireless Siemens Networks has a clear vision
communications. and strategy for implementing LTE/
SAE. Geared to reuse as many system
components as possible, Nokia Siemens
Networks’ LTE/SAE solution will
enable early migration to flat network
architecture, optionally with I-HSPA as
an intermediate step. Complying fully
with the 3GPP LTE/SAE standard, this
high performance mobile broadband
network will be reliable and interoperable.
By enabling its smooth, early introduction,
Nokia Siemens Networks will optimize
the LTE/SAE solution’s total value of
ownership.
14 Network Evolution LTE/SAE
15. Abbreviations
3GPP Third Generation LSTI LTE-SAE Trial Initiative
Partnership Project m2m Machine-to-Machine
AAA Authentication, MGW Media Gateway
Authorization, Accounting MIMO Multiple Input / Multiple
aGW Access Gateway Output
AS Application Server MME Mobility Management Entity
ASN Access Service Network NGMN Next Generation of Mobile
BS Base Station Networks
BSC Base Station Controller OFDM Orthogonal Frequency
BSS Base Station Subsystem Division Multiplexing
BTS Base Transceiver Station PCF Policy Control Function
CDMA Code Division Multiple PCRF Policy and Charging Rule
Access Function
DSL Digital Subscriber Line PDN-GW Packet Data Network
EDGE Enhanced Data rates Gateway
for GSM Evolution PDSN Packet Data Serving Node
EGPRS Enhanced General Packet PS Packet-switched
Radio Service PSTN Public Switched
eNode B enhanced Node B Telephone Network
ePDG Evolved Packet Data QAM Quadrature Amplitude
Gateway Modulation
FDMA Frequency Division Multiple QoS Quality of service
Access RAN Radio Access Network
FMC Fixed Mobile Convergence RF Radio Frequency
FTP File Transfer Protocol RNC Radio Network Controller
GGSN Gateway GPRS Service SAE System Architecture
Node Evolution
GSM Global System for Mobile SAE GW System Architecture
Communications Evolution Gateway
HA Home Agent SC-FDMA Single Carrier Frequency
HLR Home Location Register Multiple Access
HSDPA High-Speed Downlink SGSN Service GPRS Service
Packet Access Node
HSPA High-Speed Packet Access SMS Short Message Service
HSUPA High-Speed Uplink Packet UE User Equipment
Access UL Uplink
HDTV High-Definition Television UMTS Universal Mobile
HSS Home Subscriber Server Telecommunications
I-HSPA Internet High-Speed Packet System
Access VoIP Voice over IP
IMS IP Multimedia Subsystem WCDMA Wideband Code Division
IP Internet Protocol Multiple Access
ISD Inter Site Distance
LTE Long-Term Evolution
References
[1] NGMN white paper version 3.0:
Next Generation Mobile Networks Beyond HSPA and EVDO
http://www.ngmn.org/fileadmin/content/documents/downloads/
White_Paper_-_Beyond_HSPA_and_EVDO.pdf
Network Evolution LTE/SAE 15
