A slide presentation of LTE fundamentals

1. UMTS Long Term
Evolution LTE
Reiner
StuhlfauthReiner.Stuhlfauth@rohde-
schwarz.com
Training Centre
Rohde & Schwarz,
Germany
Subject to change - Data without tolerance limits is not binding.
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2011 ROHDE & SCHWARZ GmbH & Co. KG
Test & Measurement Division
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ROHDE & SCHWARZ GmbH & Co. KG, Training Center, Mhldorfstr. 15, 81671 Munich, Germany

2. Overview 3GPP UMTS Evolution
Driven by Data Rate and Latency Requirements
WCDMA HSDPA/HSUPA HSPA+ LTE
384 kbps downlink 14 Mbps peak downlink 28 Mbps peak downlink 100 Mbps peak downlink
128 kbps uplink 5.7 Mbps peak uplink 11 Mbps peak uplink 50 Mbps peak uplink
RoundTripTime~150ms RoundTripTime<100ms RoundTripTime <50 ms RoundTripTime~10 ms
3GPP Release 99/4 3GPP Release 5/6 3GPP Release 7 7 3GPP Release 8 8
3GPP Release 99/4 3GPP Release 5/6
2003/4 2005/6 (HSDPA) 2008/9 2009/10
2007/8 (HSUPA)
Approx. year of specification freezing
November 2012 | LTE Introduction | 3

3. Overview 3GPP UMTS evolution
HSDPA/ LTE and LTE-
WCDMA HSPA+WCDMA
HSUPA HSPA+ advanced
3GPP 3GPP Study3GPP Release 99/4 3GPP Release 73GPP Release 5/6 3GPP Release 8release Item initiated
App. year of 2005/6 (HSDPA)
2008/20092003/4 2010network rollout 2007/8 (HSUPA)
Downlink LTE: 150 Mbps* (peak) 100 Mbps high mobility
HSPA+: 42 Mbps (peak)384 kbps (typ.) 28 Mbps (peak)14 Mbps (peak)data rate 1 Gbps low mobility
Uplink
LTE: 75 Mbps (peak)128 kbps (typ.) 5.7 Mbps (peak) 11 Mbps (peak)data rate
Round
LTE: ~10 ms< 50 ms< 100 ms~ 150 msTrip Time
*based on 2x2 MIMO and 20 MHz operation
November 2012 | LTE Introduction | 4

4. Overview TD-SCDMA evolution towards
LTE TDD
TD-LTE
TD-SCDMA HSDPA HSUPA
HSPA+
3GPP release 3GPP Release 4 3GPP Release 5 3GPP Release 7 3GPP Release 8
Downlink
384/128 kbps (typ.) 2.8 Mbps (peak) 2.8 Mbps (peak)* LTE:100 Mbps(req.)
data rate
Uplink data rate 128 kbps (typ.) 128 kbps (typ.) 2.2 Mbs (peak)* LTE: 50 Mbps (req.)
* Higher data rate with the use of multi carrier possible
November 2012 | LTE Introduction | 5

5. Why LTE?
Ensuring Long Term Competitiveness of UMTS
l LTE is the next UMTS evolution step after HSPA and HSPA+.
l LTE is also referred to as
EUTRA(N) = Evolved UMTS Terrestrial Radio Access (Network).
l Main targets of LTE:
l Peak data rates of 100 Mbps (downlink) and 50 Mbps (uplink)
l Scalable bandwidths up to 20 MHz
l Reduced latency
l Cost efficiency
l Operation in paired (FDD) and unpaired (TDD) spectrum
November 2012 | LTE Introduction | 6

6. Introduction to UMTS LTE: Key
parameters
Frequency
UMTS FDD bands and UMTS TDD bands
Range
1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHzChannel
bandwidth,
6 15 25 50 75 1001 Resource
Resource Resource Resource Resource Resource ResourceBlock=180 kHz
Blocks Blocks Blocks Blocks Blocks Blocks
Modulation Downlink: QPSK, 16QAM, 64QAM
Schemes Uplink: QPSK, 16QAM, 64QAM (optional for handset)
Downlink: OFDMA (Orthogonal Frequency Division Multiple Access)
Multiple Access
Uplink: SC-FDMA (Single Carrier Frequency Division Multiple Access)
Downlink: Wide choice of MIMO configuration options for transmit diversity, spatial
MIMO
multiplexing, and cyclic delay diversity (max. 4 antennas at base station and handset)
technology
Uplink: Multi user collaborative MIMO
Downlink: 150 Mbps (UE category 4, 2x2 MIMO, 20 MHz)
Peak Data Rate 300 Mbps (UE category 5, 4x4 MIMO, 20 MHz)
Uplink: 75 Mbps (20 MHz)

7. LTE/LTE-A Frequency Bands
(FDD)
Uplink (UL) operating band Downlink (DL) operating bandE - UTRA
BS receive UE transmit BS transmit UE receiveOperating Duplex Mode
Band
1 1920 MHz - 1980 MHz 2110 MHz - 2170 MHz FDD
2 1850 MHz - 1910 MHz 1930 MHz - 1990 MHz FDD
3 1710 MHz - 1785 MHz 1805 MHz - 1880 MHz FDD
4 1710 MHz - 1755 MHz 2110 MHz - 2155 MHz FDD
5 824 MHz - 849 MHz 869 MHz - 894MHz FDD
6 830 MHz - 840 MHz 875 MHz - 885 MHz FDD
7 2500 MHz - 2570 MHz 2620 MHz - 2690 MHz FDD
8 880 MHz - 915 MHz 925 MHz - 960 MHz FDD
9 1749.9 MHz - 1784.9 MHz 1844.9 MHz - 1879.9 MHz FDD
10 1710 MHz - 1770 MHz 2110 MHz - 2170 MHz FDD
11 1427.9 MHz - 1452.9 MHz 1475.9 MHz - 1500.9 MHz FDD
12 698 MHz - 716 MHz 728 MHz - 746 MHz FDD
13 777 MHz - 787 MHz 746 MHz - 756 MHz FDD
14 788 MHz - 798 MHz 758 MHz - 768 MHz FDD
17 704 MHz - 716 MHz 734 MHz - 746 MHz FDD
18 815 MHz - 830 MHz 860 MHz - 875 MHz FDD
19 830 MHz - 845 MHz 875 MHz - 890 MHz FDD
20 832 MHz - 862 MHz 791 MHz - 821 MHz FDD
21 1447.9 MHz - 1462.9 MHz 1495.9 MHz - 1510.9 MHz FDD
22 3410 MHz - 3500 MHz 3510 MHz - 3600 MHz FDD
November 2012 | LTE Introduction | 13

8. LTE/LTE-A Frequency Bands
(TDD) Uplink (UL) operating band Downlink (DL) operating band
E - UTRA
BS receive UE transmit BS transmit UE receive
Operating Duplex Mode
Band
33 1900 MHz - 1920 MHz 1900 MHz - 1920 MHz TDD
34 2010 MHz - 2025 MHz 2010 MHz - 2025 MHz TDD
35 1850 MHz - 1910 MHz 1850 MHz - 1910 MHz TDD
36 1930 MHz - 1990 MHz 1930 MHz - 1990 MHz TDD
37 1910 MHz - 1930 MHz 1910 MHz - 1930 MHz TDD
38 2570 MHz - 2620 MHz 2570 MHz - 2620 MHz TDD
39 1880 MHz - 1920 MHz 1880 MHz - 1920 MHz TDD
40 2300 MHz - 2400 MHz 2300 MHz - 2400 MHz TDD
3400 MHz - 3400 MHz -
41 TDD
3600MHz 3600MHz
November 2012 | LTE Introduction | 14

9. LTE frequency allocation -
FDD
= Uplink frequency = Downlink frequency
November 2012 | LTE Introduction | 16

10. Orthogonal Frequency Division Multiple Access
the modulation scheme for LTE in downlink andOFDM is
uplink (as reference)
Some technical explanation about our physical base: radio
link aspects
November 2012 | LTE Introduction | 17

11. What does it mean to use the radio channel?
Using the radio channel means to deal with aspects like:
C
A
D
B
ReceiverTransmitter
MPP
Time variant channel
Doppler effect
attenuationFrequency selectivity
November 2012 | LTE Introduction | 18

12. Types of degradation in cellular
networks
l Multiple Access Interference (MAI)
l Inter cell interference
l Intra cell interference
l Adjacent channel interference
l Co channel interference
l Fading
l Large scale fading
- Known as log-normal fading or shadowing
- Depends on distance between transmitter and receiver
l Small scale fading - due to Multipath propagation and Doppler shift
- Depends on signal bandwidth, relative velocity, environment
November 2012 | LTE Introduction | 19

13. What is
OFDM?
Single carrier
transmission,
e.g. WCDMA
Broadband, e.g. 5MHz for WCDMA
Orthogonal
Frequency
Division
Multiplex
Several 100 subcarriers, with x kHz spacing
November 2012 | LTE Introduction | 27

14. OFDM signal generation
e.g. QPSK
00 11 01 10 01 01 11 01 > .
h*(sin jwt + cos jwt
)
h*(sin jwt + cos jwt
)
=> S h * (sin.. + cos > )
Frequency
time
OFDM
symbol
duration ? tNovember 2012 | LTE Introduction | 29

15. OFDM
Symbol
OFDM
symbol
duration ? t
November 2012 | LTE Introduction | 33

16. Inter-Carrier-Interference
(ICI) 10
Σ ΜΧ (
φ )
0
-10
-20
-30
xx
S
-40
-50
-60
-70
-1 -0.5 0 0.5 1
f -1 f 0 f 1
ff -2 f 2
ICIProblem of MC - FDM
Overlapp of neighbouring subcarriers
Inter Carrier Interference (ICI).
Solution
"Special" transmit g s (t) and receive filter g r (t) and frequencies f k allows
orthogonalsubcarrier
Orthogonal Frequency Division Multiplex (OFDM)
November 2012 | LTE Introduction | 34

17. Rectangular
Pulse
A(f)
Convolution
sin(x)/x
t
f
? t
? f
time frequency
November 2012 | LTE Introduction | 35

18. Orthogonality
Orthogonality condition: ? f = 1/ ? t
? f
November 2012 | LTE Introduction | 36

19. ISI and ICI due to
channel
Symbol ll-1 l+1
L L
η ( ν )
Receiver DFTn
Window
Delay spread
L L
L L
L L
fade out (ISI)fade in (ISI)
November 2012 | LTE Introduction | 37

20. ISI and ICI: Guard Interval
Symbol ll-1 l+1
L L
η ( ν ) T G > Delay Spread
Receiver DFTn
Window
Delay spread
L L
L L
L L
Guard Interval guarantees the suppression of ISI!
November 2012 | LTE Introduction | 38

21. Guard Interval as Cyclic Prefix
Cyclic Prefix
Symbol ll-1 l+1
L L
η ( ν ) T G > Delay Spread
Receiver DFTn
Window
Delay spread
L L
L L
L L
Cyclic Prefix guarantees the suppression of ISI and ICI!
November 2012 | LTE Introduction | 39

22. Synchronisation
Cyclic Prefix
l + 1OFDM Symbol : l 1 l
CP CPCP CP
Metric
-Search window
~n
November 2012 | LTE Introduction | 40

23. DL CP-OFDM signal generation
chainl OFDM signal generation is based on Inverse Fast Fourier Transform
(IFFT) operation on transmitter side:
N UsefulData QAM OFDM Cyclic prefix1:N N:1symbol IFFT OFDMsource Modulator symbols insertionstreams symbols
Frequency Domain Time Domain
l On receiver side, an FFT operation will be used.
November 2012 | LTE Introduction | 41

24. OFDM: Pros and Cons
Pros:
scalable data rate
efficient use of the available bandwidth
robust against fading
1-tap equalization in frequency domain
Cons:
high crest factor or PAPR. Peak to average power ratio
very sensitive to phase noise, frequency- and clock-offset
guard intervals necessary (ISI, ICI) reduced data rate
November 2012 | LTE Introduction | 42

25. MIMO
Multiple Input Multiple Output
Antennas
November 2012 | LTE Introduction | 43

26. MIMO is defined by the number of Rx / Tx
Antennasand not by the Mode which is
supported
Mode
SISO Typical todays wireless Communication System1 1
Single Input Single Output
Transmit Diversity
MISO l Maximum Ratio Combining (MRC)1 1
l Matrix A also known as STC
Multiple Input Single OutputM l Space Time / Frequency Coding (STC / SFC)
Receive Diversity
SIMO l Maximum Ratio Combining (MRC)1 1
Single Input Multiple Output Receive / Transmit Diversity
M
Spatial Multiplexing (SM) also known as:
l Space Division Multiplex (SDM)
l
MIMO True MIMO
1 1 l Single User MIMO (SU-MIMO)
l Matrix BMultiple Input Multiple OutputM M
Space Division Multiple Access (SDMA) also known as:
l Multi User MIMO (MU MIMO)
l Virtual MIMO
l Collaborative MIMODefinition is seen from Channel
BeamformingMultiple In = Multiple Transmit Antennas
November 2012 | LTE Introduction | 44

27. MIMO modes in
LTE
-Spatial Multiplexing
-Tx diversity
-Multi-User MIMO
-Beamforming
-Rx diversity
Increased
Increased
Throughput per
Throughput at
UEBetter S/N Node B
November 2012 | LTE Introduction | 45

28. RX
Diversity
Maximum Ratio Combining depends on different fading of the
two received signals. In other words decorrelated fading
channels
November 2012 | LTE Introduction | 46

29. TX Diversity: Space Time
Coding
Fading on the air interface
data
The same signal is transmitted at differnet
antennas
space Aim: increase of S/N ratio
increase of throughput*s 1 s 2
Alamouti Coding = diversity gain
Σ 2 = time approaches*s 2 s 1
RX diversity gain with MRRC!
Alamouti Coding -> benefit for mobile communications
November 2012 | LTE Introduction | 47

30. MIMO Spatial
Multiplexing C=B*T*ld(1+S/N)
SISO:
Single Input
Single Output
Higher capacity without additional spectrum!
MIMO: S
T B ld ( 1 + )
?
Χ =
min( N T , N R )
i
N
ii = 1
Multiple Input i
Multiple Output
Increasing
capacity per cell
November 2012 | LTE Introduction | 48

31. The MIMO
promisel Channel capacity grows linearly with antennas
Max Capacity ~ min(N TX , N
RX )
l Assumptions
l Perfect channel knowledge
l Spatially uncorrelated fading
l Reality
l Imperfect channel knowledge
l Correlation ? 0 and rather unknown
November 2012 | LTE Introduction | 49

32. Spatial
Multiplexing
Coding Fading on the air interface
data
data
<200%200%100%Throughput:
Spatial Multiplexing: We increase the throughput
but we also increase the interference!
November 2012 | LTE Introduction | 50

33. Introduction - Channel
Model II
Correlation of
propagation
h 11
pathes
h 21
s 1 r 1
h M
R1
h 12
estimatess 2 h 22 r 2
Transmitter Receiverh M
R2
h 1M
h 2M
T
T
N Tx N Rx
h M
sN Tx r NRx
antennas
RMT
antennas
s rH
Rank indicator
Capacity ~ min(N TX , N RX ) max. possible rank!
But effective rank depends on channel, i.e. the
correlation situation of H
November 2012 | LTE Introduction | 51

34. Spatial Multiplexing
prerequisitesDecorrelation is achieved by:
difficultl Decorrelated data content on each spatial stream
l Large antenna spacing Channel
condition
l Environment with a lot of scatters near the antenna
(e.g. MS or indoor operation, but not BS)
Technical
l Precoding assist
But, also possible
that decorrelation
l Cyclic Delay Diversity is not given
November 2012 | LTE Introduction | 52

35. MIMO: channel interference +
precoding
MIMO channel models: different ways to combat against
channel impact:
I.: Receiver cancels impact of channel
II.: Precoding by using codebook. Transmitter assists receiver in
cancellation of channel impact
III.: Precoding at transmitter side to cancel channel impact
November 2012 | LTE Introduction | 53

36. MIMO - work shift to transmitter
Channel ReceiverTransmitter
November 2012 | LTE Introduction | 57

37. MIMO
precodingprecoding
Ant1
Ant2 t
+
1
2 S1
t
+
1
-11precoding
S =0
tt
November 2012 | LTE Introduction | 59

38. MIMO - codebook based
precodingPrecoding
codebook
noise
s r+ RA H
receivertransmitter channel
Precoding Matrix Identifier, PMI
Codebook based precoding creates
some kind of "beamforming lite"
November 2012 | LTE Introduction | 60

39. MIMO: avoid inter-channel interference - future
outlook
e.g. linear precoding:
Y=H*F*S+VV 1,k
+S Link adaptation
H Space timeTransmitter
receiverF
+x k
y k
V M,k
Feedback about H
Idea: F adapts transmitted signal to current channel conditions
November 2012 | LTE Introduction | 61

40. MAS: "Dirty Paper" Coding - future
outlook
l Multiple Antenna Signal Processing: "Known Interference"
l Is like NO interference
l Analogy to writing on "dirty paper" by changing ink color accordingly
"Known"Known"Known"Known
InterferenceInterferenceInterferenceInterference
is Nois Nois Nois No
Interference"Interference"Interference"Interference"
November 2012 | LTE Introduction | 62

41. Spatial
Multiplexing
Codeword Fading on the air interface
data
Codeword
data
Spatial Multiplexing: We like to distinguish the 2 useful
Propagation passes:
How to do that? => one idea is SVD
November 2012 | LTE Introduction | 63

42. Idea of Singular Value
Decomposition MIMOs1 r1
know
r= H s+n s2 r2
channel H
Singular Value
Decomposition
~ ~s1 r1
SISO
wanted ~ ~s2 r2
~ = D s + n~ ~
r
channel D
November 2012 | LTE Introduction | 64

43. MIMO transmission modes
Transmission mode 2
Transmit
diversity PDCCH indication via
DCI format 1 or 1A
Codeword is sent
redundantly over several
streams
1 codeword
PDSCH transmission via
2 Or 4 antenna ports No feedback regarding
antenna selection or
precoding needed
November 2012 | LTE Introduction | 72

44. MIMO transmission
modes
Closed loop MIMO =
UE feedback needed regarding
Transmission mode 6 precoding and antenna
Transmit diversity or Closed loop selection
spatial multiplexing with 1 layer
PDCCH indication via
DCI format 1A
1 codeword PDSCH transmission
via 2 or 4 antenna ports
PDCCH indication via
DCI format 1B
Codeword is split into
1
streams, both streams havecodeword
to be combined
feedback
PDSCH spatial multiplexing, only 1 codeword
November 2012 | LTE Introduction | 76

45. Beamforming
Closed loop precoded
Adaptive Beamforming beamforming
Classic way Kind of MISO with channel
knowledge at transmitter
Antenna weights to adjust beam
Precoding based on feedback
Directional characteristics
No specific antenna
Specific antenna array geometrie array geometrie
Dedicated pilots required Common pilots are sufficient
November 2012 | LTE Introduction | 78

46. Spatial multiplexing vs
beamforming
Spatial multiplexing increases throughput, but looses coverage
November 2012 | LTE Introduction | 79

47. Spatial multiplexing vs
beamforming
Beamforming increases coverage
November 2012 | LTE Introduction | 80

48. System
architectureevolution ,
SAE +IP
multimediasubsystem ,
IMS
November 2012 | LTE Introduction | 81

49. 3 GPP System Architecture
Evolution Signaling interfaces
Data transport interfaces
RAN
Access PDN
directly or via IMS
MME PDNUE Evolved nodeB
IMSS-GW P-GW
PSTNEvolved Packet Core
external
IMS to control
All interfaces are packet switched access + data
transfer
November 2012 | LTE Introduction | 82

50. LTE: EPS
Bearer
E-UTRAN EPC Internet
UE eNB S-GW P-GW Peer
Entity
End-to-end Service
EPS Bearer External Bearer
Radio Bearer S1 Bearer S5/S8 Bearer
Radio S1 S5/S8 Gi
November 2012 | LTE Introduction | 83

51. What is
IMS?A high level
summary
l The success of the internet, using the Internet Protocol (IP) for
providing voice, data and media has been the catalyst for the
convergence of industries, services, networks and business models,
l IP provides a platform for network convergence enabling a
service provider to offer seamless access to any services, How
to merge IPanytime, anywhere, and with any device,
and cellularl 3GPP has taken these developments into account world??
with specification of IMS,
l IMS stands for I P M ultimedia S ubsystem,
l IMS is a global access-independent and standard-based IP
connectivity and service control architecture that enables
various types of multimedia services to end-users using
common internet-based protocols,
l Defines an architecture for the convergence of audio,
video, data and fixed and mobile networks.
November 2012 | LTE Introduction | 84

52. IMS: Reference Model (3GPP/3GPP2)
November 2012 | LTE Introduction | 85

53. IMS simplified
structure
November 2012 | LTE Introduction | 86

54. IMS protocol
structure
user plane
Control plane Voice messaging
video
SIP/SDP IKE RTP MSRP
UDP / TCP / SCTP
IP / IP secLayer 3 control
Layer 1/2Layer 1/2 (other IP CAN)
Mobile com specific protocols IMS specific protocols
November 2012 | LTE Introduction | 87

55. LTE physical
layeraspect
s
November 2012 | LTE Introduction | 88

56. Basic OFDM
parameter LTE
1
φ = 15 κΗζ =
T
F s = N FFT
f
N FFT
Φ σ = 3 . 84 Mcps
256
f
= 2048N FFT
Coded symbol rate= R
Sub-carrier CP
S/P IFFTMapping insertion
N Data symbolsTX
Size-N FFT
November 2012 | LTE Introduction | 89

57. Cyclic prefix
lengthNormal cyclic prefix length: 1st CP is longer
1 2 3 4 5 6 7
1 slot = 0,5msecMismatch in time!
1st Cyclic prefix is longer
1 2 3 4 5 6 7 Normal CP
OFDM OFDM OFDM OFDM OFDM OFDM Extended CPCP CP CP CP CP CPSymbol Symbol Symbol Symbol Symbol Symbol
2 different Cyclic prefix lengths are defined
November 2012 | LTE Introduction | 90

58. Resource block
definition
1 slot = 0,5msec
Resource block
=6 or 7 symbols
In 12 subcarriers
12
subc
arrier
s
Resource element
ULN symb or N symbDL
6 or 7,
Depending on
cyclic prefix
November 2012 | LTE Introduction | 91

59. LTE: new physical channels for data and
control Physical Control Format Indicator Channel PCFICH:
Indicates Format of PDCCH
Physical Downlink Control Channel PDCCH:
Downlink and uplink scheduling decisions
Physical Downlink Shared Channel PDSCH: Downlink data
Physical Hybrid ARQ Indicator Channel PHICH:
ACK/NACK for uplink packets
Physical Uplink Shared Channel PUSCH: Uplink data
Physical Uplink Control Channel PUCCH:
ACK/NACK for downlink packets, scheduling requests, channel quality info
November 2012 | LTE Introduction | 92

60. LTE
Downlink
OFDMA time-frequency multiplexing
frequency
QPSK, 16QAM or 64QAM modulation
UE4
1 resource block =
180 kHz = 12 subcarriers UE5
UE3
UE2
UE6
Subcarrier spacing = 15 kHz time
UE1
1 subframe =
1 slot = 0.5 ms = 1 ms= 1 TTI*=*TTI = transmission time interval
7 OFDM symbols** 1 resource block pair** For normal cyclic prefix duration
November 2012 | LTE Introduction | 93

61. Adaptive modulation and
coding
Transportation block size
FECUser data
Flexible ratio between data and FEC = adaptive coding
November 2012 | LTE Introduction | 97

62. Channel Coding
Performance
November 2012 | LTE Introduction | 98

63. Automatic repeat request, latency
aspects Transport block size = amount of
data bits (excluding redundancy!)
TTI, Transmit Time Interval = time
duration for transmitting 1 transport
block
Transport block
Round
Trip
Time
ACK/NACK
Network UE
Immediate acknowledged or non-acknowledged
feedback of data transmission
November 2012 | LTE Introduction | 99

64. HARQ principle: Stop and
Wait
? t = Round trip time
Data Data Data Data Data Data Data Data Data DataTx
ACK/NACK
Demodulate, decode, descramble,
Rx
FFT operation, check CRC, etc.
process
Processing time for receiver
Described as 1 HARQ process
November 2012 | LTE Introduction | 100

65. HARQ principle:
Multitasking
? t = Round trip time
Data Data Data Data Data Data Data Data Data DataTx
ACK/NACK
Demodulate, decode, descramble,
Rx
FFT operation, check CRC, etc.
process
ACK/NACK
Processing time for receiver
Demodulate, decode, descramble,Rx
FFT operation, check CRC, etc.
process
t
Described as 1 HARQ process
November 2012 | LTE Introduction | 101

66. LTE Round Trip Time
RTTn+4 n+4 n+4
ACK/N
ACKPDCC
H
PHICH
Downlink
HARQData DataUL
Uplink
t=0 t=1 t=2 t=3 t=4 t=5 t=6 t=7 t=8 t=9 t=0 t=1 t=2 t=3 t=4 t=5
1 frame = 10 subframes
8 HARQ processes
RTT = 8 msec
November 2012 | LTE Introduction | 102

67. HARQ principle: Soft
combining
l T i is a e am l o h n e co i g
Reception of first transportation block.
Unfortunately containing transmission errors
November 2012 | LTE Introduction | 103

68. HARQ principle: Soft
combining
l hi i n x m le f cha n l c ing
Reception of retransmitted
transportation block.
Still containing transmission errors
November 2012 | LTE Introduction | 104

69. HARQ principle: Soft
combining1st transmission with puncturing scheme P1
l T i is a e am l o h n e co i g
2nd transmission with puncturing scheme P2
l hi i n x m le f cha n l c ing
Soft Combining = S of transmission 1 and 2
l Thi is an exam le of channel co ing
Final decoding
l This is an example of channel coding
November 2012 | LTE Introduction | 105

70. Hybrid
ARQChase Combining = identical
retransmission Turbo Encoder output (36 bits)
Systematic Bits
Parity 1
Parity 2
Transmitted Bit Rate Matching to 16 bits (Puncturing)
Original Transmission Retransmission
Systematic Bits
Parity 1
Parity 2
Punctured Bit Chase Combining at receiver
Systematic Bits
Parity 1
Parity 2
November 2012 | LTE Introduction | 106

71. Hybrid
ARQIncremental
Redundancy Turbo Encoder output (36 bits)
Systematic Bits
Parity 1
Parity 2
Rate Matching to 16 bits (Puncturing)
Original Transmission Retransmission
Systematic Bits
Parity 1
Parity 2
Punctured Bit Incremental Redundancy Combining at receiver
Systematic Bits
Parity 1
Parity 2
November 2012 | LTE Introduction | 107

72. LTE Physical
Layer:SC-FDMA in
uplink
Single Carrier Frequency
DivisionMultiple
Access
November 2012 | LTE Introduction | 108

73. LTE
Uplink:How to generate an SC-FDMA signal in
theory?
Coded symbol rate= R
Sub-carrier CP
DFT IFFTMapping insertion
N TX symbols
Size-N FFTSize-N TX
LTE provides QPSK,16QAM, and 64QAM as uplink modulation schemes
DFT is first applied to block of N TX modulated data symbols to transform them into
frequency domain
Sub-carrier mapping allows flexible allocation of signal to available sub-carriers
IFFT and cyclic prefix (CP) insertion as in OFDM
Each subcarrier carries a portion of superposed DFT spread data symbols
Can also be seen as " pre-coded OFDM " or " DFT-spread OFDM "
November 2012 | LTE Introduction | 109

74. LTE
Uplink:How does the SC-FDMA signal
look like?
In principle similar to OFDMA, BUT
: In OFDMA, each sub-carrier only carries information related to one
specific symbolIn SC-FDMA, each sub-carrier contains information of ALL transmitted
symbols
November 2012 | LTE Introduction | 110

75. LTE
uplinkSC-FDMA time-frequency
multiplexing1 resource block =
180 kHz = 12 subcarriers Subcarrier spacing = 15 kHz
frequency
UE1 UE2 UE3
1 slot = 0.5 ms =
7 SC-FDMA symbols**
1 subframe =
1 ms= 1 TTI*
UE4 UE5 UE6
*TTI = transmission time interval
** For normal cyclic prefix duration
time QPSK, 16QAM or 64QAM modulation
November 2012 | LTE Introduction | 111

76. LTE
Uplink:baseband signal
generation
UE specific
Scrambling code
Modulation Transform SC-FDMAResource
Scrambling
mapper precoder element mapper signal gen.
Mapping on
physical 1 stream =
Discrete
Ressource, several
FourierAvoid QPSK i.e. subcarriers,
Transformconstant 16 QAM subcarriers based on
sequences 64 QAM not used for Physical
(optional) reference ressource
signals blocks
November 2012 | LTE Introduction | 112

77. LTE Physical
Layer:
Reference signals - general
aspects
Reference signals in
Downlink
Reference signals in
Uplink
November 2012 | LTE Introduction | 113

78. LTE Reference signals in UL and DL
overview
l i nk U plown i nkD
Downlink reference signals:
Uplink reference signals:
Primary synchronisation signal
Random Access Preamble
Secondary synchronisation signal
Uplink demodulation reference signal
Cell specific reference signals
Sounding reference signal
UE specific reference signals
= based on pseudo random bit sequences
= based on Zhadoff-Chu sequences
MBMS specific reference signals
= only used for special applications
November 2012 | LTE Introduction | 114

79. Downlink Reference
Signals Cell-specific reference signal
R 0 R 0
One
antenna
port R 0R 0
freque
ncy
R 0R 0
R 0 R 0
l = 0 l = 6 l = 0 l = 6
time
Cell specific reference signals
Pseudo random bit sequence, based on physical cell ID
Staggered in frequency + time
Distributed over channel bandwidth, always sent
November 2012 | LTE Introduction | 115

80. MIMO channel estimation due to reference
signals Estimate h 11
h 11
Estimate h 21
h 12
h 21 Estimate h 22h 22
Estimate h 12
Antenna 1 Antenna 2
November 2012 | LTE Introduction | 116

81. MIMO in LTE
(DL)Reference Symbols /
Pilots Antenna 0R0
R1 Antenna 1
R1 R3 R0 R1 R2 R0
R2 Antenna 2
R3 Antenna 3
R0 R2 R1 R0 R3 R1
12
subcar
riers Different Tx antennas
R1 R3 R0 R1 R2 R0
Can be recognized
separately
R0 R2 R1 R0 R3 R1
1 subframe
November 2012 | LTE Introduction | 117

82. Cell recognition due to physical cell
identityCell specific reference signals depend on N cell ID
ceenreferCell ficspe pec i
cific s eNodeB 2Cell
refer
enc
e
Physical Cell
eNodeB 1,
identity B
Physical
Cell
Neighbour cells should have different
identity A
physical layer cell identities to be distinguished
November 2012 | LTE Introduction | 118

83. LTE
Uplink:Reference
Signals
2 different purposes:
1. Uplink channel estimation for uplink coherent
demodulation/detection
(reference symbol on 4th SC-FDMA symbol)
2. Channel sounding: uplink channel-quality estimation for
better scheduling decisions
(position tbd)
November 2012 | LTE Introduction | 119

84. LTE Uplink: Reference Signals when
PUSCH time0123456 0123456 0123456 0123456
Allocated
bandwidth
Example
structure
SRS bandwidth configurationfrequency
Allocation for PUSCH
Demodulation Reference Signal: Uplink channel estimation for uplink coherent
demodulation/detection
Sounding Reference Signal SRS: Channel sounding: uplink channel-quality estimation for
better scheduling decisions
November 2012 | LTE Introduction | 120

85. Sounding reference
signalFrequency selective channel
allcoated bandwidth
eNodeB configures the UE when and where to send
sounding reference signals
Sounding reference signals in uplink may assist the eNodeB to investigate
frequency selectivity
=> Maybe change frequency scheduling
November 2012 | LTE Introduction | 121

86. Security
aspects
power
control
random
access
Handover
aspects
November 2012 | LTE Introduction | 122

87. LTE security aspects:
USIMModell of UMTS Subscriber Identity Module, USIM
Statements from TS 33.401:
A Rel-99 or later USIM shall be sufficient for accessing E-UTRAN
Access to E-UTRAN with a 2G SIM shall not be granted.
November 2012 | LTE Introduction | 123

88. LTE fundamentals
Downlink power allocation (1 RB)
For PDSCH power in samePDSCH power to RS, where NO referenceCell-specific PDCCH power
symbol as reference signal ansignals are present, is UE specific andreference signal depending
additional cell specific offsetsignaled by higher layers as P A ( ? A ).power (RS power), on ? B / ? A
is applied, that is signaled bysignaled in SIB Type 2
higher layers as P B ( ? B ).
[Power]
-50.00 dBm
P A = -4.77 dB
2011 ¸
Rohde&S
chwarz y]-54.77 dBm cen
quP B = 3 (-3.98 dB)
re
[F-58.75 dBm
rrie
ar
bc
Su
[Time]1311 127 9 103 5 6 81 2 40
OFDM symbols
PDSCH - Physical Downlink Shared Channel PDCCH - Physical Downlink Control Channel
November 2012 | LTE Introduction | 126

89. RACH Preamble (RAP)
l RACH Preamble consists of
- CAZAC (Zadoff / Chu Sequence) in TDD/FDD -> orthogonality
- Cyclic Prefix Easy processing in frequency domain
- Guard Time Avoids Interference by no UL-Synchronization
l Different formats for different cell sizes: 0-3 (FDD: 1,2,3 Subframes), 4 (TDD: 1
Symbol)
November 2012 | LTE Introduction | 132

90. LTE Protocol
Architecture
November 2012 | LTE Introduction | 133

91. EUTRAN stack: protocol layers
overviewMM ESM User plane
Radio Resource Control
RRC
Packet Data Convergence
PDCP
Contr
ol &
Meas
urem
ents
Radio Bearer
Radio Link Control
RLC
Logical channels
Medium Access Control
MAC
Transport channels
PHYSICAL LAYER
November 2012 | LTE Introduction | 134

92. LTE -
channels
November 2012 | LTE Introduction | 135

93. Control
plane
Broadcast
Paging
RRC connection setup
Radio Bearer Control
Mobility functions
UE measurement control >
EPS bearer management
Authentication
ECM_IDLE mobility handling
Paging origination in ECM_IDLE
Security control >
EPS = Evolved packet system
RRC = Radio Resource Control
NAS = Non Access Stratum
ECM = EPS Connection Management
November 2012 | LTE Introduction | 136

94. EPS Bearer Service
Architecture
E-UTRAN EPC Internet
UE eNB S-GW P-GW Peer
Entity
End-to-end Service
EPS Bearer External Bearer
Radio Bearer S1 Bearer S5/S8 Bearer
Radio S1 S5/S8 Gi
November 2012 | LTE Introduction | 137

95. LTE TDD and FDD
mode ofoperation
November 2012 | LTE Introduction | 138

96. TDD versus FDD
Downlink
Guard band needed
Uplink
Independent
resources in uplink +
downlink
Down- and Uplink
No duplexerTiming and UL/DL
neededconfiguration
needed
November 2012 | LTE Introduction | 139

97. Paired spectrum not always available -> use TDD mode
November 2012 | LTE Introduction | 140

98. General comments
What is called "Advantages of TDD vs. FDD
mode"
l Data traffic,
l Asymmetric setting between downlink and uplink possible,
depending on the situation,
See interference aspects:
UL - DL and inter-cell
l Channel estimation,
l Channel characteristic for downlink and uplink same,
In principle yes:
But hardware influence!
And: Timing delay UL and DL
l Design,
l No duplexer required, simplifies RF design and reduce costs.
But most UEs will be dual-
mode: FDD and TDD!
November 2012 | LTE Introduction | 141

99. LTE TDD mode - overview
7 different UL/DL configurations are defined
Characteristics + differences of UL/DL configurations:
Number of subframes dedicated to Tx and Rx
Number of Hybrid Automatic Repeat Request, HARQ processes
HARQ process timing: time between first transmission and retransmission
Scheduling timing: What is the time between PDCCH and PUSCH?
9 different configurations for the "special subframe" are defined
Definition of how long are the DL and UL pilot signals and how much
control information can be sent on it. -> also has an impact on cell size
Differences between Uplink and Downlink in TD-LTE
Characteristic of HARQ: Synchronuous or asynchronuous
Number of Hybrid Automatic Repeat Request, HARQ processes
HARQ process timing: time between first transmission and
retransmission
November 2012 | LTE Introduction | 143

100. LTE TDD: frame structure
type 2
Used
Always Always Optionally
Alwaysfor UL used as
DL UL DLor DL special
subframe
Subframe# 0 Subframe# 2 Subframe # 3 Subframe#4 Subframe #5 Subframe #7 Subframe #8 Subframe #9
One subframe,
DwPTS GP UpPTSDwPTS GP UpPTS
DwPTS = PDCCH, P-Sync, Reference symbol, User Data
GP = main Guard Period for TDD operation
UpPTS = PRACH, sounding reference signal
November 2012 | LTE Introduction | 144

101. LTE Rel9 /
LTE-Rel 10 (= LTE-
Advanced)
Technology
Outlook
Reiner
StuhlfauthReiner.Stuhlfauth@rohde-
schwarz.com
Training Centre
Rohde & Schwarz,
Germany

102. Technology evolution path
2005/2006 2009/2010 2011/20122007/2008 2013/2014
EDGE, 200 kHz EDGEevo VAMOSGSM/
DL: 473 kbps DL: 1.9 Mbps Double Speech
GPRS
UL: 473 kbps UL: 947 kbps Capacity
HSDPA, 5 MHzUMTS HSPA+, R7 HSPA+, R8 HSPA+, R9 HSPA+, R10
DL: 14.4 MbpsDL: 2.0 Mbps DL: 28.0 Mbps DL: 42.0 Mbps DL: 84 Mbps DL: 84 Mbps
UL: 2.0 MbpsUL: 2.0 Mbps UL: 11.5 Mbps UL: 11.5 Mbps UL: 23 Mbps UL: 23 Mbps
HSPA, 5 MHz
DL: 14.4 Mbps
UL: 5.76 Mbps
LTE (4x4), R8+R9, 20MHz LTE-Advanced R10
DL: 300 Mbps DL: 1 Gbps (low mobility)
UL: 75 Mbps UL: 500 Mbps
1xEV-DO, Rev. 0 1xEV-DO, Rev. A 1xEV-DO, Rev. B
DO-Advancedcdma 1.25 MHz 1.25 MHz 5.0 MHz
DL: 32 Mbps and beyond
2000 DL: 2.4 Mbps DL: 3.1 Mbps DL: 14.7 Mbps
UL: 12.4 Mbps and beyond
UL: 153 kbps UL: 1.8 Mbps UL: 4.9 Mbps
Fixed WiMAX Mobile WiMAX, 802.16e Advanced Mobile
scalable bandwidth Up to 20 MHz WiMAX, 802.16m
1.25 > 28 MHz DL: 75 Mbps (2x2) DL: up to 1 Gbps (low mobility)
typical up to 15 Mbps UL: 28 Mbps (1x2) UL: up to 100 Mbps
November 2012 | LTE Introduction | 157

103. The LTE evolution Rel-9
eICIC
enhancements
Relaying
Rel-10In-device
Diverse Data co-existence
Application CoMP
Rel-11
Relaying
eICIC
eMBMS
SONenhancements
enhancements
MIMO 8x8 MIMO 4x4Carrier Enhanced
Aggregation SC-FDMA
Public Warning
Positioning Home eNodeBSystem
Self Organizing
NetworkseMBMS
ULDL
Multi carrier /
DL ULDual Layer Multi-RAT
Beamforming Base Stations
LTE Release 8
FDD / TDD
November 2012 | LTE Introduction | 159

104. Location based services
The idea is not new, > so what to discuss?
Satellite based services
Location
controller
Network based services
Who will do the measurements? The UE or the network? = "assisted"
Who will do the calculation? The UE or the network? = "based"
So what is new?
Several ideas are defined and hybrid mode is possible as well,
Various methods can be combined.
November 2012 | LTE Introduction | 169

105. Measurements for
positioning
l lUE-assisted measurements. eNB-assisted measurements.
l lReference Signal Received eNB Rx - Tx time difference.
Power l TADV - Timing Advance.
(RSRP) and Reference Signal - For positioning Type 1 is of
Received Quality (RSRQ). relevance.
l RSTD - Reference Signal Time l AoA - Angle of Arrival.
Difference. l UTDOA - Uplink Time Difference
l UE Rx-Tx time difference. of Arrival.
TADV (Timing Advance)
= eNB Rx-Tx time difference + UE Rx-Tx time difference
Neighbor cell j = (T eNB-RX - T eNB-TX ) + (T UE-RX - T
UE-TX )
UL radio frame #i
RSTD - Relative time difference
between a subframe received from
neighbor cell j and corresponding
subframe from serving cell i:
T SubframeRxj - T SubframeRxi
DL radio frame #i UL radio frame #i
DL radio frame #i
Serving cell i
eNB Rx-Tx time difference is defined
UE Rx-Tx time difference is defined as T eNB-RX - T eNB-TX , where T eNB-RX is
the
RSRP, RSRQ are
as T UE-RX - T UE-TX , where T UE-RX is
the
received timing of uplink radio frame #imeasured on reference
received timing of downlink radio frame
and T eNB-TX the transmit timing ofsignals of serving cell i
#i from the serving cell i and T UE-TX the
downlink radio frame #i.
transmit timing of uplink radio frame #i.
Source: see TS 36.214 Physical Layer measurements for detailed definitions
November 2012 | LTE Introduction | 170

106. E-UTRAN UE Positioning Architecture
l In contrast to GERAN and UTRAN, the E-UTRAN positioning
capabilities are intended to be forward compatible to other access
types (e.g. WLAN) and other positioning methods (e.g. RAT uplink
measurements).
l Supports user plane solutions, e.g. OMA SUPL 2.0
UE = User Equipment
SUPL* = Secure User Plane Location
OMA* = Open Mobile Alliance
SET = SUPL enabled terminal
SLP = SUPL locaiton platform
E-SMLC = Evolved Serving Mobile
Location Center
MME = Mobility Management Entity
RAT = Radio Access Technology
*www.openmobilealliance.org/technical/release_program/supl_v2_0.aspx
Source: 3GPP TS 36.305November 2012 | LTE Introduction | 171

107. GNSS positioning methods supported
l Autonomeous GNSS
l Assisted GNSS (A-GNSS)
l The network assists the UE GNSS receiver to
improve the performance in several aspects:
- Reduce UE GNSS start-up and acquisition times
- Increase UE GNSS sensitivity
- Allow UE to consume less handset power
l UE Assisted
- UE transmits GNSS measurement results to E-SMLC where the position calculation
takes place
l UE Based
- UE performs GNSS measurements and position calculation, suppported by data >
- > assisting the measurements, e.g. with reference time, visible satellite list etc.
- > providing means for position calculation, e.g. reference position, satellite ephemeris, etc.
Source: 3GPP TS 36.305November 2012 | LTE Introduction | 172

108. GPS and GLONASS satellite
orbits
GPS:
26 Satellites
Orbital radius 26560 km
GLONASS:
26 Satellites
Orbital radius 25510 km
November 2012 | LTE Introduction | 173

109. Why is GNSS not
sufficent?
Critical scenario Very critical scenario GPS Satellites visibility (Urban)
l Global navigation satellite systems (GNSSs) have restricted
performance in certain environments
l Often less than four satellites visible: critical situation for GNSS
positioning
support required (Assisted GNSS)
alternative required (Mobile radio positioning)
Reference [DLR]
November 2012 | LTE Introduction | 174

110. Cell ID
l Not new, other definition: Cell of Origin (COO).
l UE position is estimated with the knowledge of the geographical
coordinates of its serving eNB.
l Position accuracy = One whole cell .
November 2012 | LTE Introduction | 175

111. Enhanced-Cell ID (E-
CID)
l UE positioning compared to CID is specified more
accurately using additional UE and/or E UTRAN radio
measurements:
l E-CID with distance from serving eNB position accuracy: a circle.
- Distance calculated by measuring RSRP / TOA / TADV (RTT).
l E-CID with distances from 3 eNB-s position accuracy: a point.
- Distance calculated by measuring RSRP / TOA / TADV (RTT).
l E-CID with Angels of Arrival position accuracy: a point.
- AOA are measured for at least 2, better 3 eNB's.
RSRP - Reference Signal Received Power
TOA - Time of Arrival
November 2012 | LTE Introduction | 176TADV - Timing Advance
RTT - Round Trip Time

112. Angle of Arrival
(AOA)
l AoA = Estimated angle of a UE with respect to a reference
direction (= geographical North), positive in a counter-
clockwise direction, as seen from an eNB.
l Determined at eNB antenna based
on a received UL signal (SRS).
l Measurement at eNB:
l eNB uses antenna array to estimate
direction i.e. Angle of Arrival (AOA).
l The larger the array, the more
accurate is the estimated AOA.
l eNB reports AOA to LS.
l Advantage: No synchronization
between eNB's.
l Drawback: costly antenna arrays.
November 2012 | LTE Introduction | 177

113. OTDOA - Observed Time Difference of Arrival
l UE position is estimated based on measuring TDOA of
Positioning Reference Signals (PRS) embedded into overall
DL signal received from different eNB's.
l Each TDOA measurement describes a hyperbola (line of constant
difference 2a), the two focus points of which (F1, F2) are the two
measured eNB-s (PRS sources), and along which the UE may be
located.
l UE's position = intersection of hyperbolas for at least 3 pairs of
eNB's.
November 2012 | LTE Introduction | 178

114. Positioning Reference Signals (PRS) for OTDOA
Definition
l Cell-specific reference signals (CRS) are not sufficient for
positioning, introduction of positioning reference signals
(PRS) for antenna port 6.
l SINR for synchronization
and reference signals of
neighboring cells needs to
be at least -6 dB.
l PRS is a pseudo-random
QPSK sequence similar
to CRS; PRS pattern:
l Diagonal pattern with time
varying frequency shift.
l PRS mapped around CRS to avoid collisions;
never overlaps with PDCCH; example shows
CRS mapping for usage of 4 antenna ports.
November 2012 | LTE Introduction | 179

115. Observed Time
difference
Observed Time
Difference of Arrival
OTDOA
If network is synchronised,
UE can measure time difference
November 2012 | LTE Introduction | 180

116. Public Warning System
(PWS)
l Extend the Warning System support of the E-UTRA/E-UTRAN
beyond that introduced in the Release 8 ETWS (Earthquake and
Tsunami Warning System) by providing
l E-UTRA/E-UTRAN support for multiple parallel Warning Notifications
l E-UTRAN support for replacing and canceling a Warning Notification
l E-UTRAN support for repeating the Warning Notification with a repetition
period as short as 2 seconds and as long as 24 hours
l E-UTRA support for more generic "PWS" indication in the Paging
Indication
l The requirement is to extend the UE RRC ETWS broadcast
reception mechanism and the associated paging mechanism to
accommodate reception of CMAS (Commercial Mobile Alert
System) alerts contained in a CBS message.
l New: TS 22.268 Public Warning System (PWS) Requirements
(Release 9)
November 2012 | LTE Introduction | 182

117. IMT - International Mobile
Communication
l IMT-2000
l Was the framework for the third Generation mobile communication
systems, i.e. 3GPP-UMTS and 3GPP2-C2K
l Focus was on high performance transmission schemes:
Link Level Efficiency
l Originally created to harmonize 3G mobile systems and to increase
opportunities for worldwide interoperability, the IMT-2000 family of
standards now supports four different access technologies, including
OFDMA (WiMAX), FDMA, TDMA and CDMA (WCDMA).
l IMT-Advanced
l Basis of (really) broadband mobile communication
l Focus on System Level Efficiency (e.g. cognitive network
systems)
l Vision 2010 - 2015
November 2012 | LTE Introduction | 183

118. IMT
Spectrum
MHz
MHz
Next possible spectrum
allocation at WRC 2015! MHz
MHz
November 2012 | LTE Introduction | 184

119. LTE-Advanced
Possible technology
features
Relaying Wider bandwidth
technology support
CooperativeEnhanced MIMO
base stationsschemes for DL and UL
Interference management Cognitive radio
methods methods
Radio network evolution Further enhanced
MBMS
November 2012 | LTE Introduction | 185

120. Bandwidth extension with Carrier
aggregation
November 2012 | LTE Introduction | 186

121. LTE-Advanced
Carrier
Aggregation
Contiguous carrier aggregation
Non-contiguous carrier aggregation
November 2012 | LTE Introduction | 187

122. Aggregation
l Contiguous
l Intra-Band
l Non-Contiguous
l Intra (Single) -Band
l Inter (Multi) -Band
l Combination
l Up to 5 Rel-8 CC and 100 MHz
l Theoretically all CC-BW combinations possible (e.g. 5+10+20 etc)
November 2012 | LTE Introduction | 188

123. Overview
l Carrier Aggregation (CA)
enables to aggregate up to 5 different
cells (component carriers CC), so that a
maximum system bandwidth of 100 MHz
can be supported (LTE-Advanced
requirement).
l Each CC = Rel-8 autonomous cell
Cell 2Cell 1
- Backwards compatibility
l CC-Set is UE specific
- Registration Primary (P)CC UE1 UE4 UE3 U3 UE4 U2
- Additional BW Secondary (S)CC-s 1-4
l CC2
Network perspective CC1
- Same single RLC-connection for one UE
(independent on the CC-s) UE1 UE2
CC2 CC1
- Many CC (starting at MAC scheduler) UE3
operating the UE
l For TDD
- Same UL/DL configuration for all CC-s UE4
November 2012 | LTE Introduction | 189

124. Deployment scenarios
3) Improve coverage
l #1: Contiguous frequency aggregation
- Co-located & Same coverage
- Same f
l #2: Discontiguous frequency aggregation
- Co-located & Similar coverage
- Different f
l #3: Discontiguous frequency aggregation
- Co-Located & Different coverage
- Different f
- Antenna direction for CC2 to cover blank spots
l #4: Remote radio heads
- Not co-located
- Intelligence in central eNB, radio heads = only transmission
antennas
- Cover spots with more traffic
- Is the transmission of each radio head within the cell the
same?
l #5:Frequency-selective repeaters
- Combination #2 & #4
- Different f
- Extend the coverage of the 2nd CC with Relays
November 2012 | LTE Introduction | 190

125. Physical channel arrangement in
downlink
Each component
carrier transmits P- Each component
SCH and S-SCH, carrier transmits
Like Rel.8 PBCH,
Like Rel.8
November 2012 | LTE Introduction | 191

126. Carrier aggregation: control signals + scheduling
Each CC has
its own control
channels,
like Rel.8
Femto cells:
Risk of interference!
-> main component
carrier will send
all control information.
November 2012 | LTE Introduction | 193

127. LTE-Advanced
Carrier Aggregation -
Scheduling Non-Contiguous spectrum allocationContiguous
l There is one transport block
RLC transmission buffer
(in absence of spatial
Dynamic
multiplexing) and one HARQ switching
entity per scheduled
component carrier (from the Channel Channel Channel Channel
coding coding coding coding
UE perspective),
l A UE may receive multiple HARQ HARQ HARQ HARQ
component carriers
simultaneously, Data Data Data Data
mod. mod. mod. mod.
l Two different approaches are
discussed how to inform the Mapping Mapping Mapping Mapping
UE about the scheduling for
each band, e.g. 20 MHz
l Separate PDCCH for each carrier,
l Common PDCCH for multiple carrier,
[frequency in MHz]
November 2012 | LTE Introduction | 194

128. LTE-
AdvancedCarrier Aggregation - Common and Separate
PDCCH? l Based on RAN WG1#58 the following isup to 3 (4) symbols
1 subframe = 1 msper subframe
considered being supported for LTE-Time 1 slot = 0.5 ms
Advanced,Freque
ncy l Variant I PDCCH on a component carrier
PDCCHPDCCH PDCCH PDCCH
assigns PDSCH resources on the same
PDSCH PDSCH PDSCH PDSCH
component carrier (and PUSCH resources on
a single linked UL component carrier)
- No carrier indicator field, i.e. Rel-8 PDCCH
structure (same coding, same CCE-basedPDSCH PDSCH PDSCH PDSCH
resource mapping) and DCI formatsPDCCHPDCCH PDCCH PDCCH
l Variant II PDCCH on a component carrier
can assign PDSCH or PUSCH resources in
one of multiple component carriers using the
carrier indicator field
PDSCH PDSCH PDSCH PDSCH
- Rel-8 DCI formats extended with 1 to 3 bit carrierPDCCHPDCCH PDCCH PDCCH
indicator field
- Reusing Rel-8 PDCCH structure (same coding, same
CCE-based resource mapping)
- Solutions to PCFICH detection errors on the component
Variant (I) Variant (II) Variant (III) PDSCH to be studied
Variant (IV)carrier carrying
l In both cases, limiting the number of blind
decoding is desirable,
November 2012 | LTE Introduction | 195

129. Carrier aggregation
activation
1. Establish SRB
3. Network
Activates PCC
=UL + DL
2. UE sends
Capability information
to the network
4.Network
Add secondary CC
November 2012 | LTE Introduction | 196

130. Carrier aggregation activation -
mobility 1. UE has
EUTRAN connection
active
2. Secondary CC is
added
3. Secondary CC is
removed
4. UE and network perform
Handover on primary CC
3. Secondary CC is
Added in target cell
November 2012 | LTE Introduction | 197

131. DL MIMO
Extension up to
8x8 Codeword to layer mapping for spatial multiplexing
l Max number of transport blocks: 2 Number
Number Codeword-to-layer mapping
of code
l Number of MCS fields of layers i = 0 , 1 , K M symb layer
1words
l one for each transport block
x ( 0 ) ( i ) = d ( 0 ) ( 2 i )
l ACK/NACK feedback x ( 1 ) ( i ) = d ( 0 ) ( 2 i + 1 )
l 1 bit per transport block for evaluation M symb = M symb 2 = M symb 3layer ( 0 ) ( 1 )
5 2
as a baseline x ( i ) = d ( 3 i )( 2 ) ( 1 )
x ( 3 ) ( i ) = d ( 1 ) ( 3 i + 1
)
l x ( 4 ) ( i ) = d ( 1 ) ( 3 i +
2 )Closed-loop precoding supported
l Rely on precoded dedicated x ( 0 ) ( i ) = d ( 0 ) ( 3
i )x ( 1 ) ( i ) = d ( 0 ) ( 3 i + 1
)demodulation RS (decision on DL RS) x ( 2 ) ( i ) = d ( 0 ) ( 3 i +
2 )
l M symb = M symb 3 = M symb 3layer ( 0 ) ( 1 )
Conclusion on the codeword-to- 6 2
x ( i ) = d ( 3 i )( 3 ) ( 1 )
layer mapping: x ( 4 ) ( i ) = d ( 1 ) ( 3 i + 1
)x ( 5 ) ( i ) = d ( 1 ) ( 3 i +
2 )l DL spatial multiplexing of up to eight
x ( 0 ) ( i ) = d ( 0 ) ( 3
i )layers is considered for LTE-Advanced, x ( 1 ) ( i ) = d ( 0 ) ( 3 i + 1
)l x ( 2 ) ( i ) = d ( 0 ) ( 3 i +
2 )Up to 4 layers, reuse LTE codeword-to- M symb = M symb 3 = M symb 4layer ( 0 ) ( 1 )
7 2
layer mapping, x ( 3 ) ( i ) = d ( 1 ) ( 4 i )
x ( 4 ) ( i ) = d ( 1 ) ( 4 i + 1 )
l Above 4 layers mapping - see table x ( 5 ) ( i ) = d ( 1 ) ( 4 i + 2 )
x ( 6 ) ( i ) = d ( 1 ) ( 4 i + 3 )
l Discussion on control signaling x ( 0 ) ( i ) = d ( 0 ) ( 4 i )
details ongoing x ( 1 ) ( i ) = d ( 0 ) ( 4 i + 1 )
x ( 2 ) ( i ) = d ( 0 ) ( 4 i + 2 )
x ( 3 ) ( i ) = d ( 0 ) ( 4 i + 3 )
M symb = M symb 4 = M symb 4layer ( 0 ) ( 1 )
8 2
x ( 4 ) ( i ) = d ( 1 ) ( 4 i )
x ( 5 ) ( i ) = d ( 1 ) ( 4 i + 1 )
x ( 6 ) ( i ) = d ( 1 ) ( 4 i + 2 )
x ( 7 ) ( i ) = d ( 1 ) ( 4 i + 3 )
November 2012 | LTE Introduction | 198

132. LTE-
AdvancedEnhanced uplink SC-
FDMA
l The uplink
transmission
scheme remains
SC-FDMA.
l The transmission of
the physical uplink
shared channel
(PUSCH) uses DFT
precoding.
l Two enhancements:
l Control-data
decoupling
l Non-contiguous
data transmission
November 2012 | LTE Introduction | 199

133. Significant step towards 4G:
Relaying ?
Source: TTA's workshop for the future of IMT-Advanced technologies, June 2008
November 2012 | LTE Introduction | 200

134. Radio Relaying
approach
No Improvement of SNR resp. CINR
Source: TTA's workshop for the future of IMT-Advanced technologies, June 2008
November 2012 | LTE Introduction | 201

135. L1/L2 Relaying
approach
Source: TTA's workshop for the future of IMT-Advanced technologies, June 2008
November 2012 | LTE Introduction | 202

136. LTE-Advanced
Coordinated Multipoint Tx/Rx (CoMP)
CoMP
Coordination between cells
November 2012 | LTE Introduction | 203

137. Present Thrust- Spectrum Efficiency
Momentary snapshot of frequency spectrum allocation
Why not use this
part of the spectrum?
l FCC Measurements:- Temporal and geographical variations in the utilization of the assigned
spectrum range from 15% to 85%.
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138. ODMA - some
ideas.
BTS
Mobile devices behave as
relay station
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139. There will be enough topics
for future trainings
Thank you for your attention!
Comments and questions
welcome!
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