This is presented as a part of fulfilment of M.Tech Seminar at IIT Kharagpur.

1. Long Term Evolution (LTE)
Technology
Presented by
GHANSHYAM MISHRA
11EC63R22
M.Tech,
RF & Microwave Engineering
IIT KHARAGPUR.

2. OUTLINE:
Generation of wireless mobile technologies
Targets for LTE
LTE architecture
LTE enabling technologies:
OFDM
MIMO antenna technology

3. Continued….
Spectrum for LTE deployments
Comparative study of 3GPP LTE and Wi-MAX
LTE network performance
LTE- Advanced
References

4. GENERATION OF WIRELESS
MOBILE COMMUNICATION
GENERATION FEATURES THROUGHPUT TECHNOLOGY
1G Analog 14.4 Kbps(peak) AMPS
2G Digital , Narrowband, 9.6/14.4 Kbps TDMA(IS-136), GSM,
Circuit switched data CDMA (IS-95)
2.5 G Packet switched data 171.2 Kbps(peak) GPRS
20-40 Kbps
3G Digital, broadband 3.1Mbps(peak) CDMA 2000, UMTS
and packet data 500-700Kbps EDGE
3.5 G > 2 Mbps Upto 3.6/7.2/14.4 HSPA
Mbps(peak)
1-3 Mbps
4G Digital broadband 100-300Mbps (peak) WIMAX,LTE-A
packet , all IP , very 3.5 Mbps
high throughput

5. Beyond 3G
 Evolutionary path beyond 3G
◦ – Mobile class targets 100 Mbps with high
mobility
◦ – Local area class targets 1 Gbps with low
mobility
 3GPP is currently developing evolutionary/
revolutionary systems beyond 3G
◦ – 3GPP Long Term Evolution (LTE)
 IEEE 802.16-based WiMAX is also evolving
towards 4G through 802.16m

6. MOTIVATION FOR 3G
EVOLUTION
CURRENT GENERATION SUPER 3G
Voice communication VoIP, high quality video conferencing
SMS, MMS Video messaging
Internet browsing Super-fast internet
Downloadable games Online gaming with mobility
Downloadable video High quality audio & video streaming
No TV service Broadcast TV on-demand
Peer-to-peer messaging Wide-scale distribution of video clips
Mobile payment
File transfer
Many other innovative ideas

7. LTE Targets
 Peak data rate
– 100 Mbps DL/ 50 Mbps UL within 20 MHz
bandwidth.
– Up to 200 active users in a cell (5 MHz)
– Less than 5 ms user-plane latency
 Mobility
– Optimized for 0 ~ 15 km/h.
– 15 ~ 120 km/h supported with high performance.
– Supported up to 350 km/h or even up to 500
km/h.
 Spectrum flexibility: 1.25 ~ 20 MHz
 Reduced capex/opex via simple architecture

8. LTE ARCHITECTURE
 Radio Interfaces
Higher Data Throughput
Lower Latency
More Spectrum Flexibility
Improved CAPEX and OPEX
 IP Core Network
Support of non-3GPP Accesses
Packet Only Support
Improved Security
Greater Device Diversity
 Service Layer
More IMS Applications (MBMS, PSS, mobile TV now IMS
enabled)
Greater session continuity

9. LTE ARCHITECTURE:

10. LTE ARCHITECTURE
 Main logical nodes in EPC are:
PDN Gateway (P-GW)
Serving Gateway (S-GW)
Mobility Management Entity (MME)
 EPC also includes other nodes and functions, such:
Home Subscriber Server (HSS)
Policy Control and Charging Rules Function (PCRF)
 EPS only provides a bearer path of a certain QoS, control of
multimedia applications is provided by the IP Multimedia
Subsystem (IMS), which considered outside of EPS
 E-UTRAN solely contains the evolved base stations, called
eNodeB or eNB

11. LTE Enabling Technologies
 Two main technologies
1.Orthogonal Frequency Division Multiplexing
(OFDM)
2.Multiple-Input Multiple-Output (MIMO)
Antenna technology

12. OFDM
 We have a high rate (hence, large bandwidth) stream of
modulation symbols Xk (ex. QAM)
 Needs to be transmitted on a frequency selective fading
channel
 Stream Xk is divided into N low rate parallel sub-
streams
 Bandwidth of each sub-stream is N times narrower
 Each sub-stream is carried by one subcarrier
 Received must restore each Xk without interference
from current or previously transmitted sub-streams

13. OFDM Concept
 Transmitted OFDM Signal
 Received OFDM Signal

14. OFDM Concept
guard
X1
x
e jω0
Serial to Parallel
X1 XN-1 Tg Tb
x
Add
jω
+ Guard
e 1 xn
1 N −1
 2π kn 
X N-1
x ωk = 2πk/N xn =
N
∑ X k exp 
 N 

e jωN −1 k =0
IFFT
0
1 Unused subcarriers
Xk = 0
time
N-1
frequency
OFDM Symbol
Ts =Tb+ Tg

15. OFDM Concept:
 OFDM modulation using IFFT
 Guard time (cyclic prefix) is added to
protect against inter-symbol interference
 Guard subcarriers to protect against
neighbor channels at both sides
 Some subcarriers are used as pilots for
channel estimation
 After equalization, receiver performs FFT
to retrieve back the stream Xk

16. OFDM ADVANTAGES
 OFDM is spectrally efficient
IFFT/FFT operation ensures that sub-carriers do
not interfere with each other.
 OFDM has an inherent robustness against narrowband
interference.
Narrowband interference will affect at most a
couple of sub channels.
Information from the affected sub channels can
be erased and recovered via the forward error
correction (FEC) codes.
 Equalization is very simple compared to Single-Carrier
systems

17. OFDM ADVANTAGES
 OFDM has excellent robustness in multi-path environments.
Cyclic prefix preserves orthogonality between
sub-carriers.
Cyclic prefix allows the receiver to capture multi-
path energy more efficiently.
 Ability to comply with world-wide regulations:
Bands and tones can be dynamically turned on/off
to comply with changing regulations.
 Coexistence with current and future systems:
Bands and tones can be dynamically turned on/off
for enhanced coexistence with the other devices.

18. MIMO
 Signal transmitted from multiple antennas (Multiple In)
 Signal received by multiple antennas (Multiple Out)
TX RX
M N
antennas antennas
• Receiver combines the received signals and optimally
combine energy from MxN channels
• Two main types of MIMO
 Transmit Diversity
 Spatial Multiplexing

19. MIMO 2X2, Transmit Diversity
 Take M=2 and N=2
 Diversity order 4

20. MIMO 2x2, Spatial Multiplexing
ro = s o g o + s1 g 1
r1 = s o g 2 + s1 g 3
 Purpose is to increase data rate (2x2 gives twice data rate)
 The 4 gains must be known at receiver
 Spatial multiplexing is a transmission technique in MIMO to transmit
independent and separately encoded data signals from each of the
multiple transmit antenna .

21. Spectrum for LTE
deployments
 An operator may introduce LTE in ‘new’ bands where it is
easier to deploy 10 MHz or 20 MHz carriers.
e.g. 2.6 GHz band(IMT Extension band) or Digital Dividend
spectrum700, 800 MHz Or in re-farmed existing mobile
bands e.g. 850, 900, 1700, 1800, 1900, 2100 MHz
 Eventually LTE may be deployed in all of these bands –and
others later
 2.6 GHz (for capacity) and 700/800 MHz (wider coverage,
improved in-building) is a good combination
 LTE offers a choice of carrier bandwidths: 1.4 MHz to 20
MHz; the widest bandwidth will be needed for the highest
speeds

22. Comparative study of 3GPP
LTE and Wi-MAX
 WiMAX (Worldwide Interoperability for
Microwave
Access), is a wireless communication system that can
provide broadband access on a large-scale coverage.
 It enhances the WLAN (IEEE 802.11) by extending
the wireless access to Wide Area Networks and
Metropolitan Area Networks.

23. Parameter WiMAX LTE
Duplex method TDD FDD and TDD
Bandwidth 5 and 10 MHz 1.25, 3, 5, 10, 15 & 20 MHz
Frame size 5 ms 10 ms with 10 sub-frames
Multiplex Access DL OFDMA OFDMA
Multiplex Access UL OFDMA SC-FDMA
Scheduling speed Every frame (5 ms) Every sub-frame (1 ms)
Subcarrier spacing 10.9 kHz 15 kHz
Maximum DL Data rate 46 Mbps (10 MHz band) 50 Mbps (10 MHz band)
(SISO)
Modulation QPSK, 16QAM, 64 QAM QPSK, 16QAM, 64 QAM
Diversity MIMO up to 2x2 MIMO up to 4x4
TD & SM TD & SM

24. Advantages/disadvantages for WiMAX and LTE
Parameter/Criterion WiMAX(+/-) LTE (+/-)
Availability ++ -
Migration costs - ++
Frequency band options + ++
Peak data rates + ++
Adaptive antenna systems + ++
UL performances + ++
DL performances + ++
Mobility + ++
Radio access modes + ++
(TDD&FDD)
QoS provisioning ++ ++

25. LTE network deployments
April 7, 2010:
The number of
mobile operators
who have
committed to
deploy LTE
advanced mobile
broadband systems
has more than
doubled in the past
year. There are
now 64 operators
committed to LTE
network
deployments in 31
countries,
according to the
Global mobile
Suppliers
Association (GSA)

26. LTE commercial networks
-performance
 Signals Research Group conducted the first ever extensive
independent drive test evaluation of a commercial LTE network,
assessing the performance of the Telia SoneraLTE networks in
Stockholm and Oslo, and reported to GSA:
 “While still in its infancy, commercial LTE networks in Stockholm and
Oslo already outperform many fixed broadband connections, offering
average data rates of 16.8Mbps (peak = 50Mbps) and 32.1Mbps
(peak = 85Mbps) in 10MHz and 20MHz, respectively. Measured data
rates would have been even higher if it had not been for the stringent
test methodology, which focused almost entirely on vehicular testing.”
Signals Research Group, LLC “Signals Ahead,” March 2010

27. LTE: some industry
forecasts
 Maravedis: The number of LTE subscribers worldwide will
pass 200 million in 2015
 Strategy Analytics: the global LTE handset market will
reach 150 million sales units by 2013
 ABI Research: by 2013 operators will spend over $8.6
billion on LTE base stations infrastructure
 IDC: Spending on LTE equipment will exceed
WiMAXequipment spend by end 2011, with worldwide
LTE infrastructure revenues approaching USD 8 billion by
2014
 Global mobile Suppliers Association (GSA): up to 22 LTE
networks are anticipated to be in commercial service by
end 2010, and at least 45 by end 2012
 Gartner: long Term Evolution will be the dominant next-
generation mobile broadband technology

28. FUTURE OF LTE
LTE-Advanced (LTE-A)
 LTE-A shall have same or better performance
than LTE
 Peak data rate (peak spectrum efficiency)
Downlink: 1 Gbps, Uplink: 500 Mbps
 Peak spectrum efficiency
Downlink: 30 bps/Hz, Uplink: 15 bps/Hz
 Same requirements as LTE for mobility,
coverage, synchronization, spectrum flexibility
etc

29. References:
[1] Erik Dahlman, Stefan Parkvall, Johan Sköld, Per Beming, "3G Evolution –
HSPA and LTE for Mobile Broadband", 2nd edition, Academic Press, 2008,
ISBN 978-0-12-374538-5.
[2] K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems: From
OFDM and MC-CDMA to LTE and WiMAX, 2nd Edition, John Wiley & Sons,
2008, ISBN 978-0-470-99821-2.
[3] H. Ekström, A. Furuskär, J. Karlsson, M. Meyer, S. Parkvall, J. Torsner, and
M. Wahlqvist, "Technical Solutions for the 3G Long-Term Evolution," IEEE
Commun. Mag., vol. 44, no. 3, March 2006, pp. 38–45.
[4] “The Long Term Evolution of 3G” on Ericsson Review no.2, 2005.
[5] www.3gpp.org

30. THANK YOU