LTE is a 4G wireless technology developed by 3GPP to provide high-speed data and media transport, as well as high-capacity voice support into the next decade. It combines OFDM and MIMO to significantly increase peak data rates while improving spectral efficiency and lowering costs. LTE aims to meet carrier needs through flexible scalable bandwidth, support for FDD and TDD spectrum, and simplified network architecture. It is designed to evolve GSM, WCDMA and CDMA networks towards an all-IP packet-switched system.
2. 2
ABSTRACTABSTRACT
LTE is a 4G wireless broadband technology developed byLTE is a 4G wireless broadband technology developed by
Third Generation Partnership Project (3GPP), an industrial trade group.Third Generation Partnership Project (3GPP), an industrial trade group.
The 3GPP Long Term Evolution (LTE) represents a majorThe 3GPP Long Term Evolution (LTE) represents a major
advance in cellular technology. LTE is a natural evolution of 3GPP GSM &advance in cellular technology. LTE is a natural evolution of 3GPP GSM &
WCDMA networks. It is also an evolution candidate for 3GPPs CDMAWCDMA networks. It is also an evolution candidate for 3GPPs CDMA
networks. LTE itself is a new paradigm in access, with a new modulationnetworks. LTE itself is a new paradigm in access, with a new modulation
technique, OFDM (Orthogonal Frequency Division Multiplex), and antennatechnique, OFDM (Orthogonal Frequency Division Multiplex), and antenna
technology, MIMO (Multiple Input Multiple Output). LTE is designed totechnology, MIMO (Multiple Input Multiple Output). LTE is designed to
meet carrier needs for high-speed data and media transport as well asmeet carrier needs for high-speed data and media transport as well as
high-capacity voice support well into the next decade. LTE is wellhigh-capacity voice support well into the next decade. LTE is well
positioned to meet the requirements of next-generation mobile networks.positioned to meet the requirements of next-generation mobile networks.
It will enable operators to offer high performance, mass-market mobileIt will enable operators to offer high performance, mass-market mobile
broadband services, through a combination of high bit-rates and systembroadband services, through a combination of high bit-rates and system
throughput – in both the up-link and down-link – with low latency.throughput – in both the up-link and down-link – with low latency.
LTE infrastructure is designed to be as simple as possibleLTE infrastructure is designed to be as simple as possible
to deploy and operate, through flexible technology that can be deployed into deploy and operate, through flexible technology that can be deployed in
a wide variety of frequency bands. LTE offers scalable bandwidths, froma wide variety of frequency bands. LTE offers scalable bandwidths, from
less than 5MHz up to 20MHz, together with support for both FDD pairedless than 5MHz up to 20MHz, together with support for both FDD paired
and TDD unpaired spectrum. The LTE–SAE architecture reduces theand TDD unpaired spectrum. The LTE–SAE architecture reduces the
number of nodes, supports flexible network configurations and provides anumber of nodes, supports flexible network configurations and provides a
high level of service availability. Furthermore, LTE–SAE will inter-operatehigh level of service availability. Furthermore, LTE–SAE will inter-operate
with GSM, WCDMA/HSPA, TD-SCDMA and CDMA.with GSM, WCDMA/HSPA, TD-SCDMA and CDMA.
3. 33
CONTENTSCONTENTS
Revolution towards LTERevolution towards LTE
What is LTE ?What is LTE ?
Why LTE?Why LTE?
GoalsGoals
3GPP Evolution3GPP Evolution
MotivationMotivation
LTE performance requirementsLTE performance requirements
Key Features of LTEKey Features of LTE
LTE Network ArchitectureLTE Network Architecture
System Architecture Evolution (SAE)System Architecture Evolution (SAE)
LTE Frame StructureLTE Frame Structure
OFDMOFDM
Multiple Antenna TechniquesMultiple Antenna Techniques
Business OpportunitiesBusiness Opportunities
ServicesServices
Is LTE ready ?Is LTE ready ?
Who is committed ?Who is committed ?
LTE vs WiMAXLTE vs WiMAX
ConclusionsConclusions
ReferencesReferences
4. 4
Revolution Towards LTERevolution Towards LTE
Long Term Evolution (LTE) is a 4G wireless broadbandLong Term Evolution (LTE) is a 4G wireless broadband
technology developed by the Third Generation Partnershiptechnology developed by the Third Generation Partnership
Project (3GPP), an industry trade group.Project (3GPP), an industry trade group.
Introduction :Introduction :
Although 3G technologies deliver significantly higher bit ratesAlthough 3G technologies deliver significantly higher bit rates
than 2G technologies, there is still a great opportunity forthan 2G technologies, there is still a great opportunity for
wireless service providers to capitalize on the ever- increasingwireless service providers to capitalize on the ever- increasing
demand for “Wireless Broadband” and take advantage of thedemand for “Wireless Broadband” and take advantage of the
technology innovation that improves the economics of deployingtechnology innovation that improves the economics of deploying
mobile broadband networks.mobile broadband networks.
5. 5
What is LTE ?What is LTE ?
LTE is a natural evolution of 3GPP GSM & WCDMA networks. It is alsoLTE is a natural evolution of 3GPP GSM & WCDMA networks. It is also
an evolution candidate for 3GPPs CDMA networks. LTE itself is a newan evolution candidate for 3GPPs CDMA networks. LTE itself is a new
paradigm in access, with a new modulation technique, OFDM (Orthogonalparadigm in access, with a new modulation technique, OFDM (Orthogonal
Frequency Division Multiplex), & antenna technology, MIMO (Multiple InputFrequency Division Multiplex), & antenna technology, MIMO (Multiple Input
Multiple Output). LTE is designed to meet carrier needs for high-speed dataMultiple Output). LTE is designed to meet carrier needs for high-speed data
and media transport as well as high-capacity voice support well into theand media transport as well as high-capacity voice support well into the
next decade.next decade.
Why LTE ?Why LTE ?
LTE , combining OFDM & MIMO, will provide on 2 to 5 times greaterLTE , combining OFDM & MIMO, will provide on 2 to 5 times greater
spectral efficiency than most advanced 3G networks, reducing the cost perspectral efficiency than most advanced 3G networks, reducing the cost per
bit & allowing better economics for operators & end users. In addition tobit & allowing better economics for operators & end users. In addition to
enabling fixed to mobile migrations of Internet applications such as Voiceenabling fixed to mobile migrations of Internet applications such as Voice
over IP (VoIP), video streaming, music downloading, mobile TV & manyover IP (VoIP), video streaming, music downloading, mobile TV & many
others, LTE networks also provide the capacity to support an explosion inothers, LTE networks also provide the capacity to support an explosion in
demand for connectivity from a new generation of consumer devicesdemand for connectivity from a new generation of consumer devices
tailored to those new mobile applicationstailored to those new mobile applications
6. 66
GOALS of LTEGOALS of LTE
GoalsGoals includeinclude
Significantly increase peak data rates, scaledSignificantly increase peak data rates, scaled
linearly according to spectrum allocationlinearly according to spectrum allocation
improving spectral efficiencyimproving spectral efficiency
lowering costslowering costs
improving servicesimproving services
making use of new spectrum opportunitiesmaking use of new spectrum opportunities
Improved quality of serviceImproved quality of service
better integration with other open standardsbetter integration with other open standards
7. 77
3GPP Evolution3GPP Evolution
Release 99 (2000): UMTS/WCDMARelease 99 (2000): UMTS/WCDMA
Release 5 (2002) : HSDPARelease 5 (2002) : HSDPA
Release 6 (2005) : HSUPA, MBMS (MultimediaRelease 6 (2005) : HSUPA, MBMS (Multimedia
Broadcast/Multicast Services)Broadcast/Multicast Services)
Release 7 (2007) : DL MIMO, IMS (IP Multimedia Subsystem),Release 7 (2007) : DL MIMO, IMS (IP Multimedia Subsystem),
optimized real-time services (VoIP, gaming, push-to-talk).optimized real-time services (VoIP, gaming, push-to-talk).
Release 8(2009?) :LTE (Long Term Evolution)Release 8(2009?) :LTE (Long Term Evolution)
Long Term Evolution (LTE)Long Term Evolution (LTE)
3GPP work on the Evolution of the 3G Mobile System started in3GPP work on the Evolution of the 3G Mobile System started in
November 2004.November 2004.
Currently, standardization in progress in the form of Rel-8.Currently, standardization in progress in the form of Rel-8.
Specifications scheduled to be finalized by the end of mid 2008.Specifications scheduled to be finalized by the end of mid 2008.
Target deployment in 2010.Target deployment in 2010.
8. 88
MotivationMotivation
Need for higher data rates and greater spectral efficiencyNeed for higher data rates and greater spectral efficiency
Can be achieved with HSDPA/HSUPACan be achieved with HSDPA/HSUPA
and/or new air interface defined by 3GPP LTEand/or new air interface defined by 3GPP LTE
Need for Packet Switched optimized systemNeed for Packet Switched optimized system
Evolve UMTS towards packet only systemEvolve UMTS towards packet only system
Need for high quality of servicesNeed for high quality of services
Use of licensed frequencies to guarantee quality of servicesUse of licensed frequencies to guarantee quality of services
Always-on experience (reduce control plane latencyAlways-on experience (reduce control plane latency
significantly)significantly)
Reduce round trip delayReduce round trip delay
Need for cheaper infrastructureNeed for cheaper infrastructure
Simplify architecture, reduce number of network elementsSimplify architecture, reduce number of network elements
9. 99
LTE performanceLTE performance
requirementsrequirements
Data Rate:Data Rate:
Instantaneous downlink peak data rate of 100Mbit/s in a 20MHzInstantaneous downlink peak data rate of 100Mbit/s in a 20MHz
downlink spectrum (i.e. 5 bit/s/Hz)downlink spectrum (i.e. 5 bit/s/Hz)
Instantaneous uplink peak data rate of 50Mbit/s in a 20MHzInstantaneous uplink peak data rate of 50Mbit/s in a 20MHz
uplink spectrum (i.e. 2.5 bit/s/Hz)uplink spectrum (i.e. 2.5 bit/s/Hz)
Cell rangeCell range
5 km - optimal size5 km - optimal size
30km sizes with reasonable performance30km sizes with reasonable performance
up to 100 km cell sizes supported with acceptable performanceup to 100 km cell sizes supported with acceptable performance
Cell capacityCell capacity
up to 200 active users per cell(5 MHz) (i.e., 200 active dataup to 200 active users per cell(5 MHz) (i.e., 200 active data
clients)clients)
10. 1010
LTE performance requirementsLTE performance requirements
(contd…)(contd…)
MobilityMobility
Optimized for low mobility(0-15km/h) but supports high speedOptimized for low mobility(0-15km/h) but supports high speed
LatencyLatency
user plane < 5msuser plane < 5ms
control plane < 50 mscontrol plane < 50 ms
Improved spectrum efficiencyImproved spectrum efficiency
Cost-effective migration from Release 6 Universal Terrestrial Radio AccessCost-effective migration from Release 6 Universal Terrestrial Radio Access
(UTRA) radio interface and architecture(UTRA) radio interface and architecture
Improved broadcastingImproved broadcasting
IP-optimizedIP-optimized
Scalable bandwidth of 20MHz, 15MHz, 10MHz, 5MHz and <5MHzScalable bandwidth of 20MHz, 15MHz, 10MHz, 5MHz and <5MHz
Co-existence with legacy standards (users can transparently start a call orCo-existence with legacy standards (users can transparently start a call or
transfer of data in an area using an LTE standard, and, when there is notransfer of data in an area using an LTE standard, and, when there is no
coverage, continue the operation without any action on their part usingcoverage, continue the operation without any action on their part using
GSM/GPRS or W-CDMA-based UMTS)GSM/GPRS or W-CDMA-based UMTS)
11. 1111
Key Features of LTEKey Features of LTE
Multiple access schemeMultiple access scheme
Downlink: OFDMADownlink: OFDMA
Uplink: Single Carrier FDMA (SC-FDMA)Uplink: Single Carrier FDMA (SC-FDMA)
Adaptive modulation and codingAdaptive modulation and coding
DL modulations: QPSK, 16QAM, and 64QAMDL modulations: QPSK, 16QAM, and 64QAM
UL modulations: QPSK and 16QAMUL modulations: QPSK and 16QAM
Rel-6 Turbo code: Coding rate of 1/3, two 8-state constituent encoders, and aRel-6 Turbo code: Coding rate of 1/3, two 8-state constituent encoders, and a
contention- free internal interleaver.contention- free internal interleaver.
Bandwidth scalability for efficient operation in differently sized allocatedBandwidth scalability for efficient operation in differently sized allocated
spectrum bandsspectrum bands
Possible support for operating as single frequency network (SFN) to supportPossible support for operating as single frequency network (SFN) to support
MBMSMBMS
12. 1212
Key Features of LTEKey Features of LTE
(contd.)(contd.)
Multiple Antenna (MIMO) technology for enhanced data rate andMultiple Antenna (MIMO) technology for enhanced data rate and
performance.performance.
ARQ within RLC sub layer and Hybrid ARQ within MAC sub layer.ARQ within RLC sub layer and Hybrid ARQ within MAC sub layer.
Power control and link adaptationPower control and link adaptation
Implicit support for interference coordinationImplicit support for interference coordination
Support for both FDD and TDDSupport for both FDD and TDD
Channel dependent scheduling & link adaptation for enhanced performance.Channel dependent scheduling & link adaptation for enhanced performance.
Reduced radio-access-network nodes to reduce cost, protocol-relatedReduced radio-access-network nodes to reduce cost, protocol-related
processing time & call set-up timeprocessing time & call set-up time
14. 1414
System Architecture Evolution(SAE)System Architecture Evolution(SAE)
System Architecture Evolution (aka SAE) is theSystem Architecture Evolution (aka SAE) is the
core network architecture of 3GPP's future LTEcore network architecture of 3GPP's future LTE
wireless communication standard.wireless communication standard.
SAE is the evolution of the GPRS Core Network,SAE is the evolution of the GPRS Core Network,
with some differences.with some differences.
The main principles and objectives of the LTE-SAEThe main principles and objectives of the LTE-SAE
architecture include :architecture include :
A common anchor point and gateway (GW) node for all access technologiesA common anchor point and gateway (GW) node for all access technologies
IP-based protocols on all interfaces;IP-based protocols on all interfaces;
Simplified network architectureSimplified network architecture
All IP networkAll IP network
All services are via Packet Switched domainAll services are via Packet Switched domain
Support mobility between heterogeneous RATs, including legacy systems asSupport mobility between heterogeneous RATs, including legacy systems as
GPRS, but also non-3GPP systems (say WiMAX)GPRS, but also non-3GPP systems (say WiMAX)
Support for multiple, heterogeneous RATs, including legacy systems asSupport for multiple, heterogeneous RATs, including legacy systems as
GPRS, but also non-3GPP systems (say WiMAX)GPRS, but also non-3GPP systems (say WiMAX)
15. 1515
OFDMOFDM
LTE uses OFDM for the downlink – that is, from the base station to the terminal. OFDMLTE uses OFDM for the downlink – that is, from the base station to the terminal. OFDM
meets the LTE requirement for spectrum flexibility and enables cost-efficient solutionsmeets the LTE requirement for spectrum flexibility and enables cost-efficient solutions
for very wide carriers with high peak rates. OFDM uses a large number of narrow sub-for very wide carriers with high peak rates. OFDM uses a large number of narrow sub-
carriers for multi-carrier transmission.carriers for multi-carrier transmission.
The basic LTE downlink physical resource can be seen as a time-frequency grid. In theThe basic LTE downlink physical resource can be seen as a time-frequency grid. In the
frequency domain, the spacing between the subcarriers, Δf, is 15kHz. In addition, thefrequency domain, the spacing between the subcarriers, Δf, is 15kHz. In addition, the
OFDM symbol duration time is 1/Δf + cyclic prefix. The cyclic prefix is used toOFDM symbol duration time is 1/Δf + cyclic prefix. The cyclic prefix is used to
maintain orthogonality between the sub-carriers even for a time-dispersive radiomaintain orthogonality between the sub-carriers even for a time-dispersive radio
channel.channel.
One resource element carries QPSK, 16QAM or 64QAM. With 64QAM, each resourceOne resource element carries QPSK, 16QAM or 64QAM. With 64QAM, each resource
element carries six bits.element carries six bits.
The OFDM symbols are grouped into resource blocks. The resource blocks have aThe OFDM symbols are grouped into resource blocks. The resource blocks have a
total size of 180kHz in the frequency domain and 0.5ms in the time domain. Each 1mstotal size of 180kHz in the frequency domain and 0.5ms in the time domain. Each 1ms
Transmission Time Interval (TTI) consists of two slots (Tslot).Transmission Time Interval (TTI) consists of two slots (Tslot).
In E-UTRA, downlink modulation schemes QPSK, 16QAM, and 64QAM are available.In E-UTRA, downlink modulation schemes QPSK, 16QAM, and 64QAM are available.
16. 1616
Multiple AntennaMultiple Antenna
TechniquesTechniques
MIMO employs multiple transmit and receive antennas to substantiallyMIMO employs multiple transmit and receive antennas to substantially
enhance the air interface.enhance the air interface.
It uses space-time coding of the same data stream mapped onto multipleIt uses space-time coding of the same data stream mapped onto multiple
transmit antennas, which is an improvement over traditional receptiontransmit antennas, which is an improvement over traditional reception
diversity schemes where only a single transmit antenna is deployed todiversity schemes where only a single transmit antenna is deployed to
extend the coverage of the cell.extend the coverage of the cell.
MIMO processing also exploits spatial multiplexing, allowing different dataMIMO processing also exploits spatial multiplexing, allowing different data
streams to be transmitted simultaneously from the different transmitstreams to be transmitted simultaneously from the different transmit
antennas, to increase the end-user data rate and cell capacity.antennas, to increase the end-user data rate and cell capacity.
In addition, when knowledge of the radio channel is available at theIn addition, when knowledge of the radio channel is available at the
transmitter (e.g. via feedback information from the receiver), MIMO can alsotransmitter (e.g. via feedback information from the receiver), MIMO can also
implement beam-forming to further increase available data rates andimplement beam-forming to further increase available data rates and
spectrum efficiencyspectrum efficiency
17. 1717
Advanced Antenna TechniquesAdvanced Antenna Techniques
Single data stream / userSingle data stream / user
Beam-formingBeam-forming
Coverage, longer battery lifeCoverage, longer battery life
Spatial Division Multiple Access (SDMA)Spatial Division Multiple Access (SDMA)
Multiple users in same radio resourceMultiple users in same radio resource
Multiple data stream / user DiversityMultiple data stream / user Diversity
Link robustnessLink robustness
Spatial multiplexingSpatial multiplexing
Spectral efficiency, high data rate supportSpectral efficiency, high data rate support
18. 1818
Business opportunities
LTE provides 2 to 5 times greater spectral efficiency than most advanced 3G
networks, reducing the cost per bit and allowing better economics for operators and
end users.
It is affordable mass market wireless broadband services -boosting Operator
profitability.
Faster downloads, video sharing, true Mobile TV with more channels and better
quality.
Increased peak data rates, with the potential for100 Mbps peak downstream and
50 Mbps peak upstream, reduced latency, scalable bandwidth capacity, and
backwards compatibility with existing GSM and WCDMA-HSPA and HSPA+
systems.
Future developments could yield peak throughput of the order of 300 Mbps
20. 2020
Is LTE ready?
Standards are complete (Release 8 –
March 2009)
LTE has global acceptance by
leading operators worldwide
On December 15th2009,
TeliaSonera launched the world’s
first commercial LTE services, in
Sweden and Norway
Spectrum is available to support
initial system deployments
LTE performance consistently meets
or exceeds expectations
Several trials and commercial
deployments on-going throughout the
world
110 operators in 48
countries are investing in
LTE
80 firm network
deployment commitments
30 “pre-commitment”
trials, studies
21. 2121
Who is committed?
80 LTE network commitments in 33 countries
Up to 22 LTE networks in service by end 2010
Up to 45 LTE networks in service by end 2012
30 additional pre-commitment LTE trials
22. 2222
LTE vs WiMAXLTE vs WiMAX
First, both are 4G technologies designed to move data rather than voice and both areFirst, both are 4G technologies designed to move data rather than voice and both are
IP networks based on OFDM technology.IP networks based on OFDM technology.
WiMAX is based on a IEEE standard (802.16), and like that other popular IEEE effort,WiMAX is based on a IEEE standard (802.16), and like that other popular IEEE effort,
Wi-Fi, it’s an open standard that was debated by a large community of engineersWi-Fi, it’s an open standard that was debated by a large community of engineers
before getting ratified. In fact, we’re still waiting on the 802.16m standard for fasterbefore getting ratified. In fact, we’re still waiting on the 802.16m standard for faster
mobile WiMAX to be ratified. The level of openness means WiMAX equipment ismobile WiMAX to be ratified. The level of openness means WiMAX equipment is
standard and therefore cheaper to buy — sometimes half the cost and sometimesstandard and therefore cheaper to buy — sometimes half the cost and sometimes
even less. Depending on the spectrum allotted for WiMAX deployments and how theeven less. Depending on the spectrum allotted for WiMAX deployments and how the
network is configured, this can mean a WiMAX network is cheaper to build.network is configured, this can mean a WiMAX network is cheaper to build.
As for speeds, LTE will be faster than the current generation of WiMAX, but 802.16mAs for speeds, LTE will be faster than the current generation of WiMAX, but 802.16m
that should be ratified in 2009 is fairly similar in speeds.that should be ratified in 2009 is fairly similar in speeds.
However, LTE will take time to roll out, with deployments reaching mass adoption byHowever, LTE will take time to roll out, with deployments reaching mass adoption by
2012 . WiMAX is out now, and more networks should be available later this year.2012 . WiMAX is out now, and more networks should be available later this year.
The crucial difference is that, unlike WiMAX, which requires a new network to be built,The crucial difference is that, unlike WiMAX, which requires a new network to be built,
LTE runs on an evolution of the existing UMTS infrastructure already used by over 80LTE runs on an evolution of the existing UMTS infrastructure already used by over 80
per cent of mobile subscribers globally. This means that even though developmentper cent of mobile subscribers globally. This means that even though development
and deployment of the LTE standard may lag Mobile WiMAX, it has a crucialand deployment of the LTE standard may lag Mobile WiMAX, it has a crucial
incumbent advantage.incumbent advantage.
23. 2323
ConclusionsConclusions
Thus we Studied 3GPP LTE as :Thus we Studied 3GPP LTE as :
LTE is a highly optimized, spectrally efficient, mobile OFDMA solutionLTE is a highly optimized, spectrally efficient, mobile OFDMA solution
built from the ground up for mobility, and it allows operators to offerbuilt from the ground up for mobility, and it allows operators to offer
advanced services and higher performance for new and wideradvanced services and higher performance for new and wider
bandwidths.bandwidths.
LTE is based on a flattened IP-based network architecture thatLTE is based on a flattened IP-based network architecture that
improves network latency, and is designed to interoperate on andimproves network latency, and is designed to interoperate on and
ensure service continuity with existing 3GPP networks. LTEensure service continuity with existing 3GPP networks. LTE
leverages the benefits of existing 3G technologies and enhancesleverages the benefits of existing 3G technologies and enhances
them further with additional antenna techniques such as higher-orderthem further with additional antenna techniques such as higher-order
MIMO.MIMO.
24. 2424
ReferencesReferences
http://www.3gpp.org/http://www.3gpp.org/
Towards 4G IP-based Wireless Systems,Tony Ottosson Anders Ahl´en2 AnnaTowards 4G IP-based Wireless Systems,Tony Ottosson Anders Ahl´en2 Anna
Brunstrom, Mikael Sternad and Arne Svensson,Brunstrom, Mikael Sternad and Arne Svensson,
http://db.s2.chalmers.se/download/publications/ottosson_1007.pdfhttp://db.s2.chalmers.se/download/publications/ottosson_1007.pdf
The 3G Long-Term Evolution – Radio Interface Concepts and PerformanceThe 3G Long-Term Evolution – Radio Interface Concepts and Performance
EvaluationEvaluation
http://www.ericsson.com/technology/http://www.ericsson.com/technology/
White Paper by NORTEL -Long-Term Evolution (LTE): The vision beyond 3GWhite Paper by NORTEL -Long-Term Evolution (LTE): The vision beyond 3G
http://www.nortel.com/solutions/wireless/collateral/nn114882.pdfhttp://www.nortel.com/solutions/wireless/collateral/nn114882.pdf
[Long Term Evolution (LTE): an introduction, October 2007 Ericsson White[Long Term Evolution (LTE): an introduction, October 2007 Ericsson White
Paper]Paper]
www.gsacom.com
unite.nokiasiemensnetworks.com/lte
Technical Overview of 3GPP Long Term Evolution (LTE) Hyung G. MyungTechnical Overview of 3GPP Long Term Evolution (LTE) Hyung G. Myung
http://hgmyung.googlepages.com/3gppLTE.pdfhttp://hgmyung.googlepages.com/3gppLTE.pdf