3. 3GPP Evolution
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2G: Started years ago with GSM: Mainly voice
2.5G: Adding Packet Services: GPRS,EDGE
3G: Adding 3G Air Interference: UMTS
3G Architecture:
• Support of 2G/2.5G and 3G Access
• Handover between GSM and UMTS technologies
• 3G Extensions:
• HSDPA/HSPUA
• IP Multi Media Subsystem (IMS)
• Inter-working with WLAN (I-WLAN)
• Beyond 3G:
• Long Term Evolution(LTE)
• Introduced in Release 8 of 3GPP in 2004
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4. Motivation for LTE
• Need for higher data rates
• New air interface defined by 3GPP LTE
• Need for high Qos
• Use of licensed frequencies to guarantee quality of services
• Need for cheaper infrastructure
• Simplify architecture, reduce number of network elements
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5. Requirements to be met by LTE
Fast, Efficient, Cheap, Simple
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Peak Data Rates
Spectrum efficiency
Reduced Latency
Mobility
Spectrum flexibility
Coverage
Low complexity and cost
Interoperability
Simple packet-oriented E-UTRAN architecture
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7. The Next Generation Networks Architecture
• SAE is a study within 3GPP targeting at the evolution
of the overall system architecture.
• Object is “ to develop a framework for an evolution
or migration of the 3GPP system to higher-data-rate,
lower-latency, packet optimized system that supports
multiple radio access technologies.”
• This study includes the version of an all-IP networks.
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8. UMTS 3G
NB: NodeB (base station)
RNC: Radio Network Controller
SGSN: Serving GPRS Support Node
GGSN: Gateway GPRS Support Node
LTE
eNB: Evolved NodeB
P-GW: PDN(Packet Data Network)Gateway
S-GW: Serving Access Gateway
MME: Mobility Management Entity
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9. LTE Architecture
• The architecture evolution of 3GPP LTE, involves the migration
from traditional system to all IP flat network architectures.
• It reduces the number of nodes and distributes the processing
load, therefore it reduces the latency.
• The architecture functionality is split into two parts:
• A radio access network (E-UTRAN)
• A core network (EPC)
E-UTRAN: Evolved Universal Terrestrial Radio Access Network
EPC: Evolved Packet Core
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10. E-UTRAN: Uu
Interface Roles
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Supports all services including real-time multimedia services
It contains new network elements called enhanced NodeBs (eNBs)
The function of eNBs includes all radio interface –related functions
As(Uu)Functions
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Radio Bearer management
Radio Channel
Ciphering
Radio Mobility (HO)
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11. Air Interface
Enabling Technologies
• LTE aims at better spectral flexibility, higher data
rates, low latency and improved coverage.
• To achieve the targets, LTE employs the enabling
technologies:
• OFDMA
• SC-FDMA
• MIMO
• LTE employs OFDMA for downlink and SC-FDMA for
uplink transmission.
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12. Orthogonal Multiple Access Schemes
• Downlink: OFDMA
• The available spectrum is divided into multiple carriers, called sub-carriers,
which are orthogonal to each other.
• sub-carriers are allocated dynamically among the different users.
• Each of these subcarriers is independently modulated by low rate data
stream.
• OFDM has several benefits:
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High spectral efficiency
Robust against frequency- selective and multi- path fading
Supports flexible bandwidth deployment
Facilitates frequency- domain scheduling
Well suited to advanced MIMO techniques
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13. Orthogonal Multiple Access Schemes
• Uplink: SC-FDMA
• SC-FDMA is chosen because it combines the low Peak-to-average Power
Ratio (PAPR) techniques of single-carrier transmission systems, such as
CDMA, with the multipath resistance and flexible frequency allocation of
OFDMA.
SC-FDMA has several benefits:
• Based on OFDMA with DFT precoding
• Common structure of transmission resources compared to downlink
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14. Single-Carrier Frequency Division Multiple Access
(SC-FDMA)
• The incoming bit stream is first converted to single-carrier
symbols.
• Then, data symbols in the time domain are converted to the
frequency domain(Discrete Fourier Transform).
• Then, data symbols mapped to the desired band in the
overall channel bandwidth.
• Now, they back to the time domain using Inverse Fourier
Transform.
• Finally, the Cyclic Prefix is inserted. It’s used for effectively
eliminate Inter Symbol Interference
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15. cyclic prefix refers to the prefixing of
a symbol with a repetition of the
end. Although the receiver is
typically configured to discard the
cyclic prefix samples, the cyclic prefix
serves as a guard interval.
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16. Multiple Antenna Schemes in LTE
• In DL: Tx diversity, Rx diversity, spatial multiplexing supported
(2×2,4×2 configurations).
• In UL: Only 1 Transmitter (antenna selection Tx diversity), Rx
diversity with 2 or 4 antennas at eNB supported.
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17. EPC (Evolved Packet Core)
•
The EPC consist of functional entities:
• MME (Mobile Management Entity)
E-UTRAN
EPC
• Manages mobility, UE identity, and
security parameters
• S-GW (Serving-Gateway)
• Node that terminates interface
toward e-UTRAN
• P-GW (Packet Data Network-Gateways)
• Node that terminates the interface
towards PDN (Packet Data Network)
• PCRF (Policy and charging Rules
Function)
• Controls the charging and the IP
Multimedia Subsystem configuration
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18. Integrated EPC Network Functions
• As mobile operators evolve to LTE, they will benefit from solutions
that can integrate 2G/3G and 4G functions in a single node
providing separate access through a common multimedia core.
• Support for multiple network technologies and the corresponding
multimedia core network functionality in a multi-access, multiservice environment.
GERAN: GSM EDGE Radio Access
Network
IMS: IP Multimedia Subsystem
HSS: Home Subscriber Server
SGSN: Serving GPRS Support Node
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20. SAE (System Architecture Evolution)
Objectives
• New network architecture to support the high- throughput
and low-latency LTE access system
• Simplified network architecture
• All IP network
• Support mobility between multiple heterogeneous access
system
• 2G/3G, LTE, non 3GPP access system such as WLAN, WiMAX
• Inter-3GPP handover
• Inter-3GPP and non-3GPP mobility
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25. Conclusion
• The 3GPP LTE/SAE is a future-oriented radio access
system designed to support huge traffic of future
end user requirements like high speed internet, DVBH
• The 3GPP LTE provides a framework for
standardization in the evolution towards 4G.
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