Download - LTE_Presentation.ppt
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LTE (Long Term Evolution)
Prof. Adel A. Ali
Abdurrahman A. Ashahrani
Hammod Al-Olyani
King Saud University
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Outline
Introduction & Background
What OFDM?
LTE
Conclusion
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First Generation MS
with its large size &
2G with its small size
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Introduction & Background
Analog Mobile Systems (first Generation)
Few users , expensive , large size
Second Generation (GSM)Digital system, more user, almost
voice, improved to supply data (EDGE , GPRS).
Third Generation (UMTS) Voice & data but, cell breathing (CDMA),
improved to increase the speed 7Mbps(HSPDA).
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Cell Breathing
20 Users 10 Users
-10 < C/I < -5 dB
-15 < C/I < -10 dB
-50 < C/I < -15 dB
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What OFDM ?
Subcarriers used.
The subcarriers are orthogonal to eachother and can be overlapped.
Suitable for multipath fading channels
and high data rates
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Ch.1
Ch.2 Ch.3 Ch.4 Ch.5 Ch.6 Ch.7 Ch.8 Ch.9 Ch.10
Ch.3 Ch.5 Ch.7 Ch.9
Ch.2 Ch.4 Ch.6 Ch.8 Ch.10
Ch.1
Conventional multicarrier techniques
Orthogonal multicarrier techniques OFDM
50% bandwidth saving
frequency
frequency
A
B
Traditional FDM Signal and OFDM
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All Sub carrier need to Orthogonal
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OFDM
Sub-carrier
CDMA
Signal
Channel Transfer Function
Frequency
S(f)
CDMA & OFDM in
Frequency-selective Channel
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LTE (Long Term Evaluation)
Supply Bandwidths from 1.25-20 MHz
Subcarriers spacing 15kHz.
Bit rate up to 100Mbps, and by using MIMO the
speed should reach 350Mbps !
SC-FDMA for U.L. & OFDM for D.L.
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20 MHz15 MHz10 MHz5 MHz2.5 MHz1.25 MHzTransmissionBW
0.5 msSub-frame
duration
15 kHzSub-carrier
spacing30.72
MHz
8 3.84
MHz
23.04 MHz
6 3.84
MHz
15.36 MHz
4 3.84
MHz
7.68
MHz
2 3.84
MHz
3.84
MHz
1.92 MHz
1/2 3.84
MHz
Sampling
frequency
204815361024512256128FFT size
4.694.694.694.694.694.69Sho
rtCP
Length
(s)
16.6716.6716.6716.6716.6716.67
Lo
ng
LTE modulation Specification
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LTE Time Line
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Thank you
?