LTE is used in 4G Technology. Different physical layer techniques used in LTE are described in this presentation. Majorly OFDM, MIMO and Carrier Aggregation are mentioned in this presentation. It was presented at IIT Patna.

1. LTE AND ITS
EVOLUTION
By
Jeevan Prakash-Mtech(1311EE05)

2. Motivation for LTE
 Need to ensure the continuity of
competitiveness of the 3G system for the
future.
 User demand for higher data rates and quality
of service.
 Packet switch optimized system.
 Continued demand for cost reduction(CAPEX
and OPEX)
 Low complexity.

3. LTE Overview
Fig1: GSM to LTE
Fig: Circuit and
packet domains

4. LTE evolution
Fig3: LTE and its Evolution

5. Transmission Technologies
 Downlink --- OFDMA
 Uplink--- SC-FDMA
Fig4: OFDMA and SCFDMA

6. Channel Dependent Scheduling
 Channel-dependent scheduling in a mobile-
communication system deals with the question of how
to share, between different users (different terminals),
the radio resource(s) available in the system to achieve
as efficient resource utilization as possible.
Fig5: Downlink
channel-dependent
scheduling in the
time and frequency
domains

7. ICIC-InterCell Interference
Coordination
 LTE is designed for frequency reuse 1 (To
maximize spectrum efficiency), which means
that all the neighbor cells are using same
frequency channels and therefore there is no
cell-planning to deal with the interference
issues.
 There is a high probability that a resource
block scheduled to cell edge user, is also
being transmitted by neighbor cell, resulting in
high interference, eventually low throughput or
call drops. Fig6: ICIC

8. ICIC- Cont.
 The LTE specification includes several
messages that can be communicated between
eNodeBs using the X2 interface.
Fig7: X2 and s1 interface

9. Hybrid ARQ
 Hybrid automatic repeat request (hybrid ARQ
or HARQ) is a combination of high-rate
forward error-correcting coding and ARQ error-
control.
 In practice, incorrectly received coded data
blocks are often stored at the receiver rather
than discarded, and when the retransmitted
block is received, the two blocks are
combined. This is called Hybrid ARQ with soft
combining

10. Multi Antenna Support
 MIMO is used to increase the overall bitrate.
Fig8: Multiple antennas

11. Spectrum Flexibility
 LTE supports both FDD and TDD within a single
radio-access technology, leading to a minimum
of deviation between FDD and TDD for LTE-
based radio access.
 Half-duplex FDD reduces terminal complexity as
no duplex filter is needed in the terminal.
Fig9:
Frequency-
and time-
division
duplex

12.  Increased peak data rate, DL 3 Gbps, UL 1.5
Gbps
 Higher spectral efficiency, from a maximum of
16bps/Hz in R8 to 30 bps/Hz in R10
 Increased number of simultaneously active
subscribers
 Improved performance at cell edges, e.g. for
DL 2x2 MIMO at least 2.40 bps/Hz/cell.

13. Multi Antenna Transmission

14. Carrier Aggregation
 To increase the capacity-increase the bandwidth
 Bandwidth can be extended by carrier aggregation
 Multiple component carriers are aggregated and jointly
used for transmission to/from a single terminal
Fig10: Carrier
aggregation

15. Cont..
 Using contiguous component carriers within
the same operating frequency band called
intra-band contiguous.
Fig11: Carrier aggregation-intra and inter bands

16. Relaying
 Relaying implies that the terminal
communicates with the network via a relay
node that is wirelessly connected to a donor
cell using the LTE radio-interface technology.
Fig12: Example of
Relaying

18. References
 4G LTE/LTE ADVANCED FOR MOBILE
BROADBAND by Erik Dahlman, Stefan Parkvall,
and Johan Sköld, Elsevier press,2011
 http://www.3gpp.org/technologies/keywords-
acronyms/100-the-evolved-packet-core
 http://www.3gpp.org/technologies/keywords-
acronyms/98-lte
 http://www.3gpp.org/technologies/keywords-
acronyms/97-lte-advanced
 http://3gppltee.blogspot.in/2012/09/what-is-icic-
inter-cell-interference.html

19. Thank you