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RA4120-30A - LTE RPESSLTE – EPS Overview
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Nokia Siemens Networks Academy
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Module Objectives
After completing this module, the participant should be able to:
• List the LTE/SAE main requirements
• Underline the LTE/SAE key features
• Review the 3GPP specification work concerning LTE/SAE.
• Describe the LTE Network Architecture
• List the key functionalities of the evolved NB
• Understand the protocol stack implemented on EUTRAN interfaces
• Identify the LTE Terminals categories
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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The way to the Long-Term Evolution (LTE): a 3GPP driven initiative
• LTE is 3GPP system for the years 2010 to 2020 & beyond.
• It shall especially compete with WiMAX 802.16e/m
• It must keep the support for high & highest mobility users
like in GSM/UMTS networks
• The architectural changes are big compared to UMTS
• LTE commercial launch has started early 2010.
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What are the LTE challenges?
• Best price, transparent flat rate
• Full Internet
• Click-bang responsiveness
• reduce cost per bit
• provide high data rate
• provide low latency
The Users’ expectation… ..leads to the operator’s challenges
Price per Mbyte has to be reduced to remain profitable
User experience will have an impact on ARPU
LTE: lower cost per bit and improved end user experience
UMTS HSPA I-HSPA LTE
Cost per MByte
HSPA LTE HSPA LTE
Throughput Latency
Fact
or 1
0
Factor 2-3
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LTE = Long Term Evolution
• Peak data rates of 303 Mbps / 75 Mbps
• Low latency 10-20 msEnhanced consumer experience
• Scalable bandwidth of 1.4 – 20 MHz
Easy to introduce on any frequency band
• OFDM technology
• Flat, scalable IP based architecture
Decreased cost / GB
• Next step for GSM/WCDMA/HSPA and CDMA
A true global roaming technology
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Schedule for 3GPP releases
• Next step for GSM/WCDMA/HSPA and cdma2000
A true global roaming technology
year
3GPP Rel. 99/43GPP Rel. 99/4 Rel. 5Rel. 5 Rel. 6Rel. 6 Rel. 7Rel. 7
2007200520032000 2008
HSDPAIMS
HSUPAMBMS
WLAN IW
HSPA+LTE Studies
Specification:
2009
• LTE have been developed by the same standardization organization. The target has been simple multimode implementation and backwards compatibility.
• HSPA and LTE have in common:
– Sampling rate using the same clocking frequency
– Same kind of Turbo coding
• The harmonization of these parameters is important as sampling and Turbo decoding are typically done on hardware due to high processing requirements.
• WiMAX and LTE do not have such harmonization.
Rel. 8Rel. 8
LTE & EPC
Rel. 9Rel. 9
LTE-Astudies
LTE-A: LTE-Advanced
Rel. 10Rel. 10
LTE-AUMTS/
WCDMA
2011
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Comparison of Throughput and Latency (1/2)
HSPA R6
Max. peak data rate
Mb
ps
Evolved HSPA (Rel. 7/8, 2x2 MIMO)
LTE 2x20 MHz (2x2 MIMO)
LTE 2x20 MHz (4x4 MIMO)
Downlink
Uplink
350
300
250
200
150
100
50
0HSPAevo
(Rel8)
LTE
* Server near RAN
Latency (Rountrip delay)*
DSL (~20-50 ms, depending on operator)
0 20 40 60 80 100 120 140 160 180 200
GSM/EDGE
HSPARel6
min max
ms
Enhanced consumer experience:- drives subscriber uptake
- allow for new applications
- provide additional revenue streams
• Peak data rates of 303 Mbps / 75 Mbps
• Low latency 10-20 ms
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Scalable bandwidth
• Scalable bandwidth of 1.4 – 20 MHz
Easy to introduce on any frequency band: Frequency Refarming(Cost efficient deployment on lower frequency bands supported)
Scalable Bandwidth
Urban
2006 2008 2010 2012 2014 2016 2018 2020
Rural
2006 2008 2010 2012 2014 2016 2018 2020
or
2.6 GHz
2.1 GHz
2.6 GHz
2.1 GHz
LTE
UMTS
UMTS
LTE
900 MHz
900 MHz GSM
or
GSM UMTS
LTE
LTE
LTE
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0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
HSPA R6 HSPA R6 +UE
equalizer
HSPA R7 WiMAX LTE R8
bp
s/H
z/c
ell
DownlinkUplink
Increased Spectral Efficiency
• All cases assume 2-antenna terminal reception
• HSPA R7, WiMAX and LTE assume 2-antenna BTS transmission (2x2 MIMO)
ITU contribution from WiMAX Forum shows
DL 1.3 & UL 0.8 bps/Hz/cell
Reference:
- HSPA R6 and LTE R8 from 3GPP R1-071960
- HSPA R6 equalizer from 3GPP R1-063335
- HSPA R7 and WiMAX from NSN/Nokia simulations
• OFDMA technology increases Spectral efficiency
LTE efficiency is 3 x HSPA R6 in downlinkHSPA R7 and WiMAX have Similar Spectral Efficiency
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Reduced Network Complexity
• Flat, scalable IP based architecture
Flat Architecture: 2 nodes architectureIP based Interfaces
Access Core Control
Evolved Node B Gateway
IMS HLR/HSS
Flat, IP based architecture
Internet
MME
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LTE/SAE Requirements Summary
1. Simplify the RAN:- Reduce the number of different types of RAN nodes, and their complexity.
- Minimize the number of RAN interface types.
• Increase throughput: Peak data rates of UL/DL 50/100 Mbps
• Reduce latency (prerequisite for CS replacement).
• Improve spectrum efficiency: Capacity 2-4 x higher than with Release 6 HSPA
• Frequency flexibility & bandwidth scalability: Frequency Refarming
• Migrate to a PS only domain in the core network: CSFB for initial phase
• Provide efficient support for a variety of different services. Traditional CS services will be supported via VoIP, etc: EPS bearers for IMS based Voice
• Minimise the presence of single points of failure in the network above the eNBs S1-Flex interface
• Support for inter-working with existing 3G system & non-3GPP specified systems.
• Operation in FDD & TDD modes
• Improved terminal power efficiency
A more detailed list of the requirements and objectives for LTE can be found in TR 25.913.
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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Evolved Packet Core (EPC)LTE Radio
Access Network (EUTRAN)
MME
ServingGW
PDNGW
Packet Data
Network
SAE-GW
eNode-B
LTE Radio Interface Key Features
LTE Radio Interface Key Features
• Retransmission Handling (HARQ/ARQ)
• Spectrum Flexibility
• FDD & TDD modes
• Multi-Antenna Transmission
• Frequency and time Domain scheduling
• Uplink (UL) Power Control
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Evolved Packet Core (EPC)LTE Radio
Access Network (EUTRAN)
MME
ServingGW
PDNGW
Packet Data
Network
SAE-GW
eNode-B
EUTRAN Key Features
EUTRAN Key Features:
• Evolved NodeB
• IP transport layer
• UL/DL resource scheduling
• QoS Awareness
• Self-configuration
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Evolved Packet Core (EPC)LTE Radio
Access Network (EUTRAN)
MME
ServingGW
PDNGW
Packet Data
Network
SAE-GW
eNode-B
EPC Key Features
EPC Key Features:
• IP transport layer
• QoS Awareness
• Packet Switched Domain only
• 3GPP (GTP) or IETF (MIPv6) option
• Prepare to connect to non-3GPP access networks
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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Standardisation around LTE
Next Generation Mobile Networks. Is a group of mobile operators, to provide a coherent vision for technology evolution beyond 3G for the competitive delivery of broadband wireless services.
More in www.ngmn.org
Collaboration agreement established in December 1998. The collaboration agreement brings together a number of telecommunications standards bodies: ARIB, CCSA, ETSI, ATIS, TTA, and TTC.
More in www.3gpp.org
LTE/SAE Trial Initiative. Is was founded in may 2007 by a group of leading telecommunications companies.Its aim is to prove the potential and benefits that the LTE technology can offer. More in http://www.lstiforum.com/
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From 3GPP Specs into Commercial Launch
• Historically, 1.25-1.5 years from the specs approval until backwards compatibility (ASN.1) with HSDPA and HSUPA
• Historically, 1.25-1.5 years from the backwards compatibility until commercial launch with HSDPA & HSUPA
• LTE backwards compatibility: 03/2009. First commercial launch: 12/2009
2003 2004 2005 2006 2007
1 2 3
1 2 3
1.5 years 1.5 years
1.25 years 1.25 years
1 = Specs approved
2 = Backwards compatibility
3 = 1st commercial launch
HSDPA
HSUPA
2008 2009 2010
1 2 31.25 years 0.75 years
LTE
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• End 2004 3GPP workshop on UTRAN Long Term Evolution• Beginning 2005 Study item started• December 2005 Multiple Access selected• March 2006 Functionality split between radio and core• September 2006 Study item closed & approval of the work items• December 2007 1st version of all radio specs approved • December 2008 3GPP REL. 8: content Finalized and specification frozen
3GPP LTE Specification Work
20082004 2005 2006 2007
Multiple Access Decision
RAN/CN functional split
PDCP moved from CN to EUTRAN
FDD/TDD Frame Structure Alignment
LTE Workshop
Start of the Study
Close Study and Start Work Item
1st full set of specifications
LTE R8 Content Finalized
Standardization
Technology
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• March 2009 Protocol Freezing (Backwards compatibility starts)
• December 2009 3GPP R9 was frozen
• On December 14, 2009, the world's first publicly available LTE service was opened by TeliaSonera in the two Scandinavian capitals Stockholm and Oslo.
• On September 21, 2010, MetroPCS began to roll out its LTE network in Las Vegas, Nevada
• March 2011 3GPP Release 10 was frozen.
3GPP LTE Specification Work & early deployments
20122008 2009 20010 2011
TeliaSonera launched first commercial LTE network in Sweden and Norway
Metro PCS initiates LTE deployment in the US
3GPP R8 ASN.1 Code Frozen
3GPP R9 was frozen
3GPP R10 was Frozen (LTE-Advanced)
Standardization
Deployments
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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Network Architecture Evolution
SAE GWGGSN
SGSN
RNC
Node B (NB)
Direct tunnel
GGSN
SGSN
I-HSPA
MME/SGSN
HSPA R7 HSPA R7 LTE R8
Node B + RNC
Functionality
Evolved Node B (eNB)
GGSN
SGSN
RNC
Node B (NB)
HSPA
HSPA R6
LTE
User plane
Control Plane
• Flat architecture: single network element in user plane in radio network and core network
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Evolved Packet System (EPS) Architecture - Subsystems
• The EPS architecture goal is to optimize the system for packet data transfer.
• There are no circuit switched components. The EPS architecture is made up of:
– EPC: Evolved Packet Core, also referred as SAE
– eUTRAN: Radio Access Network, also referred as LTE
LTE or eUTRAN SAE or EPC
EPS Architecture
• EPC provides access to external packet IP networks and performs a number of CN related functions (e.g. QoS, security, mobility and terminal context management) for idle and active terminals
• eUTRAN performs all radio interface related functions
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LTE/SAE Network Elements
Main references to architecture in 3GPP specs.: TS23.401,TS23.402,TS36.300
LTE-UE
Evolved UTRAN (E-UTRAN)
MME S10
S6a
ServingGateway
S1-U
S11
PDNGateway
PDN
Evolved Packet Core (EPC)
S1-MME
PCRFS7 Rx+
SGiS5/S8
Evolved Node B(eNB)
X2
LTE-Uu
HSS
Mobility Management
Entity Policy & Charging Rule
Function
SAEGateway
eNB
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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Inter-cell RRM: HO, load balancing between cells
Radio Bearer Control: setup , modifications and release of Radio Resources
Connection Mgt. Control: UE State Management,MME-UE Connection
Radio Admission Control
eNode B Meas. collection and evaluation
Dynamic Resource Allocation (Scheduler)
eNB Functions
IP Header Compression/ de-compression
Access Layer Security: ciphering and integrity protection on the radio interface
MME Selection at Attach of the UE
User Data Routing to the SAE GW
Transmission of Paging Msg coming from MME
Transmission of Broadcast Info (e.g. System info, MBMS)
• Only network element defined as part of eUTRAN.
• Replaces the old Node B / RNC combination from 3G.
• Terminates the complete radio interface including physical layer.
• Provides all radio management functions
• To enable efficient inter-cell radio management for cells not attached to the same eNB, there is a inter-eNB interface X2 specified. It will allow to coordinate inter-eNB handovers without direct involvement of EPC during this process.
Evolved Node B (eNB)
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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LTE Radio Interface & the X2 Interface
LTE-Uu interface• Air interface of LTE
• Based on OFDMA in DL & SC-FDMA in UL
• FDD & TDD duplex methods
• Scalable bandwidth: 1.4MHz - 20 MHz
X2 interface• Inter eNB interface
• X2AP: special signalling protocol (Application Part)
• Functionalities:
– In inter- eNB HO to facilitate Handover and provide data forwarding.
– In RRM to provide e.g. load information to neighbouring eNBs to facilitate interference management.
– Logical interface: doesn’t need direct site-to-site connection, i.e. can be routed via CN as well
(E)-RRC(E)-RRC User PDUsUser PDUs User PDUsUser PDUs
PDCPPDCP
..
RLCRLC
MACMAC
LTE-L1 (FDD/TDD-OFDMA/SC-FDMA)LTE-L1 (FDD/TDD-OFDMA/SC-FDMA)
TS 36.300
eNB
LTE-Uu
eNB
X2
User PDUsUser PDUs
GTP-UGTP-U
UDPUDP
IPIP
L1/L2L1/L2
TS 36.424
X2-UP(User Plane)X2-CP
(Control Plane)
X2-APX2-AP
SCTPSCTP
IPIP
L1/L2L1/L2TS 36.421
TS 36.422
TS 36.423
TS 36.421
TS 36.420
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S1-MME & S1-U Interfaces
MME
ServingGateway
S1-MME(Control Plane)
S1-U(User Plane)
NAS ProtocolsNAS Protocols
S1-APS1-AP
SCTPSCTP
IPIP
L1/L2L1/L2
User PDUsUser PDUs
GTP-UGTP-U
UDPUDP
IPIP
L1/L2L1/L2
TS 36.411
TS 36.411
TS 36.412
TS 36.413
TS 36.414
TS 36.410
eNB
S1 interface is divided into two parts:
S1-MME interface
• Control Plane interface between eNB & MME
• S1AP:S1 Application Protocol
• MME & UE will exchange NAS signaling via eNB through this interface ( i.e.
authentication, tracking area updates)
• S1 Flex: an eNB is allowed to connect to a maximum of 16 MME. (LTE2, RL20)
S1-U interface
• User plane interface between eNB & Serving Gateway.
• Pure user data interface (U=User plane)
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Terminals
• LTE Summary
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Class 1 Class 2 Class 3 Class 4 Class 5
10/5 Mbps 50/25 Mbps 100/50 Mbps 150/50 Mbps 300/75 MbpsPeak rate DL/UL
20 MHzRF bandwidth 20 MHz 20 MHz 20 MHz 20 MHz
64QAMModulation DL 64QAM 64QAM 64QAM 64QAM
16QAMModulation UL 16QAM 64QAM 16QAM 16QAM
YesRx diversity Yes YesYes Yes
1-4 TxBTS Tx diversity
OptionalMIMO DL 2x2 4x42x2 2x2
1-4 Tx 1-4 Tx 1-4 Tx 1-4 Tx
LTE UE Categories
• All categories support 20 MHz
• 64QAM mandatory in downlink, but not in uplink
(except Class 5)
• 2x2 MIMO mandatory in other classes except Class 1
Power Class
Tx Power (dBm)
Tolerance (dB)
1 [+30]
2 [+27]
3 +23 +/-2 dB
4 [+21]
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Module Contents
• LTE Requirements
• LTE Key Features
• LTE Standardization
• LTE Architecture
• Evolved NB functionalities
• EUTRAN Interfaces
• LTE Summary
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LTE: What is new?
• new radio transmission schemes:
– OFDMA in DL
– SC-FDMA in UL
– MIMO Multiple Antenna Technology
• New radio protocol architecture:
– Complexity reduction
– Focus on shared channel operation, no dedicated channels anymore
• new network architecture:
– More functionality in the base station (eNodeB)
– Focus on PS domain
– Flat architecture (2-nodes)
– All-IP
• Important for Radio Planning
– Frequency Reuse 1▪ No need for Frequency Planning
– No need to define neighbour lists in LTE
OFDMA: Orthogonal Frequency Division Multiple Access
SC-FDMA: Single Carrier Frequency Division Multiple Access
PS: Packet Switched