The document presents a technical study on Long Term Evolution (LTE), detailing its architecture, physical layer, and features such as single-carrier frequency division multiple access (SC-FDMA) and cognitive radio for resource management. It outlines the requirements for LTE and introduces LTE Advanced, which aims to fulfill the International Mobile Telecommunications (IMT) Advanced standards for 4G technology. Additionally, the document discusses channel-dependent scheduling and multiple antenna schemes to enhance performance and throughput in LTE networks.

1. 3GPP – Long Term Evolution – A Technical
Study
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Mr. Vishal Pawar
MITSOT

2. Main Topics
• Introduction to LTE
• LTE Network Architecture
• LTE Physical Layer
• SC-FDMA
• Channel Dependent Scheduling
• Cognitive Radio for LTE RRM
• Multiple antenna schemes in LTE
• LTE-Advanced
• Conclusion
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3. Introduction to LTE
• 3GPP Long Term Evolution - the next generation of wireless cellular
technology beyond 3G
• Initiative taken by the 3rd Generation Partnership Project in 2004
• Introduced in Release 8 of 3GPP
• Mobile systems likely to be deployed by 2010
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4. Requirements to be met by LTE
Fast, Efficient, Cheap, Simple
• 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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5. LTE Network Architecture
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• Simple Architecture
• Flat IP-Based Architecture
• Reduction in latency and cost
• Split between
EPC and E-UTRAN
• Compatibility with 3GPP and
non-3GPP technologies
• eNB-radio interface-related
functions
• MME-manages mobility, UE
identity and security
parameters
• S-GW-node that terminates
the interface towards E-
UTRAN

6. LTE Network Architecture
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7. June 26 2009 7

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9. LTE Frame Structure
• LTE Frame Structure
Type I (FDD)
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10. LTE Frame Structure
Type II (TDD)
June 26 2009 MITSOT_MCNE_LTE 10

11. Single-Carrier Frequency Division Multiple
Access (SC-FDMA)
• Motivation for SC-FDMA
• SC-FDMA utilizes single carrier modulation at the transmitter and
frequency domain equalization at the receiver.
• It has the best of both worlds - the low PAPR of single carrier
systems and the multipath resistance and channel dependent
subcarrier allocation features of OFDM.
• Same complexity and performance as OFDMA
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12. The “SC”-”FDMA” System
DFT-Spread OFDMA – Mapping of spread
symbols , not original symbols to subcarriers!!!
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13. Subcarrier Mapping Schemes
• Localized (LFDMA)
• Distributed (DFDMA)
• Interleaved (IFDMA)
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14. Frequency and Time Domain Representation
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Frequency Time

15. Time domain signals of LFDMA, DFDMA and
IFDMA[20]
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16. PAPR characteristics of an SC-FDMA signal [20]
Comparison of the CCDF of PAPR for LFDMA, DFDMA, IFDMA and
OFDMA
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17. Effect of roll-off factor, alpha on the PAPR[20]
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18. Why does SC-FDMA have a low PAPR?
• OFDMA
• Parallel Transmission
• Multi carrier structure
• Increase in M =>
high PAPR
• SC-FDMA
• Serial Transmission
• Each symbol
represented by a
wide signal – DFT spreads
symbols over all subcarriers
• PAPR not affected by
increase in M
Both occupy the same bandwidth with same symbol durations
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19. SC-FDMA in comparison with OFDMA and DS-
CDMA/FDE
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DS-CDMA/FDE

20. Channel Dependent Scheduling
• Channel is highly frequency
selective
• Resources in deep fade for
one user could be excellent for
another user
• Frequency selectivity of the
channel can be exploited by
using CDS to maximize
throughput
• LFDMA – frequency selective
diversity
• IFDMA – Multi user diversity
(inherently frequency diversity
is obtained)
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21. Cognitive RRM in LTE
• Link adaptation possible as network segments in LTE adapt to the
environmental changes
• System can learn from solutions that were provided in the past
• Faster response, improved performance, intelligent system
• Decisions reg. apt BW,DSA,APA and AM
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22. Cognitive Features to enhance RRM in LTE
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23. Enhanced context acquisition mechanism
architecture for cognitive intra-cell RRM
MITSOT_MCNE_LTE 23

24. Multiple Antenna Schemes in LTE
• In DL : Tx diversity, Rx diversity, Spatial multiplexing (2x2,4x2
configurations – SU-MIMO and MU-MIMO) supported
• In UL : Only 1 Transmitter (antenna selection Tx diversity ), MU-
MIMO possible, Rx diversity with 2 or 4 antennas at eNB supported
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25. LTE Advanced
• LTE doesn’t fulfill the requirements of IMT-Advanced
• 3GPP has also started work on LTE-Advanced, an evolution of LTE,
as a proposal to ITU-R for the development of IMT Advanced.
• LTE Advanced is envisioned to be the “first true 4G technology”.
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26. Requirements of LTE Advanced
• Peak data rates – 1Gbps in DL and 500 Mbps in UL
• Cell edge user data rates twice as high and average user throughput
thrice as high as in LTE
• Peak spectrum efficiency DL: 30 bps/Hz, UL: 15 bps/Hz
• Operate in flexible spectrum allocations up to 100 MHz and support
spectrum aggregation (as BW in DL >>20 MHz)
• An LTE-Advanced capable network must appear as a LTE network
for the LTE UEs
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27. Technological proposals for LTE Advanced
• Larger BW can be used for
high date rates and more
coverage at cell edges
• Advanced repeater structures
• Relaying for adaptive coding
based on link quality
MITSOT_MCNE_LTE 27
Carrier aggregation and
Spectrum aggregation

28. Thank You !
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