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TD-LTE Overview
November 2012
Bong Youl (Brian) Cho, 조 봉 열
brian.cho@nsn.com
TTA LTE/MIMO Standards/Technology Training
2 © Nokia Siemens Networks
Contents
• Why TD-LTE?
• NSN with TD-LTE
• TD-LTE technology overview
TTA LTE/MIMO Standards/Technology Training
3 © Nokia Siemens Networks
Why TD-LTE?
TTA LTE/MIMO Standards/Technology Training
4 © Nokia Siemens Networks
Difference b/w 3G-TDD and 4G-TDD
1999 2000 2001 2002 2003 2004 2005
Rel 99
Rel 4
Rel 5
Rel 6
1.28Mcps TDD
HSDPA, IMS
W-CDMA
HSUPA, MBMS, IMS+
2006 2007 2008 2009
Rel 7 HSPA+ (MIMO, HOM etc.)
Rel 8
2010 2011
LTE, SAE
Rel 9
LTE-Advanced Rel 10
GSM/GPRS/EDGE enhancements
Small LTE/SAE enhancements
LTE-Advanced
2012
Rel 11
OFDM기반의 기술 추가 및 MIMO의 본격적인 활용
TTA LTE/MIMO Standards/Technology Training
5 © Nokia Siemens Networks
Global TDD Situation
4+
Frequencies
50+
Countries
60%
World Pops
50%
Land-Mass
2.3 Global
2.6 Global
1.9 Russia, China
2.5 Japan
Informa
Over 50% of operators planning to deploy TD-
LTE
TTA LTE/MIMO Standards/Technology Training
6 © Nokia Siemens Networks
3GPP E-UTRA TDD frequency bands
E-UTRA
Operating
Band
Uplink (UL) operating band
BS receive UE transmit
Downlink (DL) operating band
BS transmit UE receive Duplex
Mode
FUL_low – FUL_high FDL_low – FDL_high
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
41 2496 MHz – 2690 MHz 2496 MHz – 2690 MHz TDD
42 3400 MHz – 3600 MHz 3400 MHz – 3600 MHz TDD
43 3600 MHz – 3800 MHz 3600 MHz – 3800 MHz TDD
44 703 MHz – 803 MHz 703 MHz – 803 MHz TDD
TTA LTE/MIMO Standards/Technology Training
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LTE-FDD, TD-LTE Integration
Standards Integration
Product Integration
Maximized commonality b/w FDD and TDD for high level of integration/interworking
FDD-LTE
TD-LTE
Glo
bal
Ro
am
ing
FDD-LTE & TD-LTE
TD
-LT
E / F
DD
-LT
E
Tra
nsp
are
nt
han
d o
ver
Fully integrated over time
TTA LTE/MIMO Standards/Technology Training
8 © Nokia Siemens Networks
TD-LTE Capacity Similar spectral efficiency for TD-LTE and LTE-FDD
5
10
15
20
25
30
35
FDD 2 x 10MHz TD-LTE 1 x 20MHz TD-LTE 1x20MHz ( FDD 2 x 20MHz )
Mbps
Downlink
Uplink
TD-LTE config.1
• DL/UL = 4/4 timeslots
• Similar DL and UL capacity as in FDD
TD-LTE config.2
• DL/UL = 6/2 timeslots
• Optimized for very asymmetric traffic
FDD-LTE
• DL = 10MHz
• UL = 10MHz
FDD-LTE
• DL = 20MHz
• UL = 20MHz
• Double spectrum
= double capacity
Similar Spectrum Efficiency
DL/UL Ratio
Flexibility
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TD-LTE – a very relevant tool for every operator
TD-LTE Early Market Opportunity
True 4G performance Comparable Performance FDD-LTE
Global & Local Roaming TD-LTE / FDD-LTE / 3GPP / 3GPP2
Affordable Spectrum Sold for 10x less than FDD equivalent
Economy of Scale • LTE Momentum Driving
Common Network Hardware
• Large Operators TD-LTE Opportunities Driving the Device Economy of Scale
Traditional CSP – Augment FDD-LTE
• Increased Capacity (Overlay/Underlay)
• or specific Apps (M2M, Video Broadcast)
Greenfield – TD-LTE main LTE network
Global roaming + potential MVNO capability with other 3GPP/3GPP2 operators for underlay in early deployment stage with transparent
WiMAX CSP – Possible migration path
• Leverage current spectrum asset
• Scope for evolution to TD-LTE when time is right
TTA LTE/MIMO Standards/Technology Training
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TD-LTE Applications Leveraging Flexible DL/UL Ratio
Mobile Reporter
- TD-LTE enable report to leverage the power of now in the field and with HD Quality and instantaneity for live studio-like dialog
- Avoid Complex, Slow & Costly deployment of TV vehicles on site UL Bias Use Case
Surveillance & Video based M2M
UL Bias Use Case
• Spot Coverage of Crowd Based Events/Gathering, Public Safety Incidents / Traffic Monitoring, Hazardous places access, Remote People monitoring, ...
- Leverage HD quality video uplink, responsive service with very long distance remote control capabilities
Transport On-Board Infotainment
DL Bias Use Case
- Layer coverage of transport networks for added capacity and supporting the infotainment nature of the likely applications used during transport
- Leverage Very High Downlink Capacity for fixed line BB like service for supporting more subscribers and high quality and innovative applications
TTA LTE/MIMO Standards/Technology Training
11 © Nokia Siemens Networks
NSN with TD-LTE
TTA LTE/MIMO Standards/Technology Training
12 © Nokia Siemens Networks
Nokia Siemens Networks LTE references 67 commercial LTE customers
61 LTE radio deals (incl. 8 TD-LTE)
32 LTE EPC deals commercially launched networks (incl. 5 TD-LTE)
35
Canada Sweden Sweden Latvia Latvia
Korea
Canada
Russia Denmark Denmark Finland Finland Lithuania
Korea
USA
Poland USA Germany Germany Estonia Estonia South
Korea USA
IMS
France Croatia Austria Slovenia India Singapore Japan
Portugal Italy Azerbaijan Bahrain Australia Japan
UAE Saudi Arabia Saudi Arabia Japan
LTE supplier to the largest operators in Japan and Korea
Brazil
TD-LTE
TD-LTE TD-LTE
TD-LTE
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13 © Nokia Siemens Networks
TD-LTE Developments
Award The Economic Figure of the
Year of the China Information Industry
for NSN innovation & leadership in TD-LTE
China Information Industry Economic Conference
Beijing, Dec 1st 2011
1st TD-LTE Femto cell demo
World’s 1st
1st CMCC/ VDF proof of tech.
100% pass MIIT lab test
E2E call with throughput >80Mbps end-to-end
2.3GHz
MIIT field trial test
IOT with UE vendors (incl. Altair, Sequans, HiSilicon, Innofidei, Qualcomm)
1st TD-LTE demo in India & Russia
1st Taiwan-Mainland TD-LTE live HD video
1st TD LTE-TD SCDMA video call controlled by IMS
1st TD-LTE – TD-SCDMA concurrent mode
World’s 1st
1st TD-LTE trial network parallel connecting to CMCC, Shanghai Expo
1st TD-LTE Open Lab
World’s 1st
Simultaneous multiple UE TD-LTE connection
World’s 1st
3GPP R8 TD-LTE E2E L3 call with comm. EPC
3GPP R8 TD-LTE call & HO
World’s 1st
World’s 1st
TD-LTE drive tour at ITU Geneva
World’s 1st
Leading vendor in MIT 2.6 GHz field trial
Successful trials in India and Russia
3 Large scale trials slots in CMCC large field trial
2010 2009 2012
First 1.3Gbps demo for LTE-A with CMCC
First to finish CMCC Ph1 large scale testing (97%)
2011
Progress
• Demos since 2009
• Commercial deals since 2011
• Significant deployments 2012
• 7 commercial deals to date
(leading)
We are here
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NSN extends TD-LTE speed record in China
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TD-LTE technology overview
TTA LTE/MIMO Standards/Technology Training
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Duplexing
• FDD
• TDD
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Duplexing – cont’d
TTA LTE/MIMO Standards/Technology Training
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LTE FDD vs TD-LTE
Same RF Structure, Same Resource Block => Same RF Power/Time/Bandwidth Density
Same Power Transmitted during the Same amount of time as FDD-LTE
LTE FDD
10MHz
10W
5W
5MHz
5MHz
10ms
10ms
TD-LTE
DL
DL Single UL Frame Resource Block
5ms
Power
Time
Spectrum
1/5 W
UL
UL
1/5 W
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3GPP LTE FDD vs. LTE TDD High degree of commonality
Features LTE FDD LTE TDD
Frame structure 1ms sub-frame 1ms sub-frame
Switching points N/A 5ms periodicity and 10 ms periodicity
BS Synchronization Asynchronous/Synchronous Synchronous
DL Control Channel Can schedule 1 DL and 1 UL
sub-frame at a time
Can schedule 1 DL and multiple
UL sub-frame at a time
UL Control Channel Single ACK/NAK corresponding
to 1 DL sub-frame
Multiple ACK/NAK corresponding
to multiple DL sub-frame
PRACH 0,1,2,3 0,1,2,3,4 (Short RACH)
Special slot usage N/A DwPTS: RS, Data and Control
UpPTS: SRS and Short RACH
Numerology, Coding, Multiple
Access, MIMO support, RS
etc.
Same Same
HARQ Timing N=8 stop-and-wait protocol
DL: Async, UL: Sync
TBD
DL: Async, UL: Sync
High Degree of Commonality
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LTE FDD vs. TDD performance comparison
FDD-LTE TD-LTE
Negligible advantage (No need of switching) Spectral Efficiency
DL/UL Balancing TD-LTE can adapt to DL/UL traffic ratio
(typical of internet traffic) Fix bandwidth for DL & UL
(typical of voice traffic)
Real Life Performance
Latency Dedicated UL/DL pipes (no need to “wait” for
UL or DL slot)
Comparable Subscriber Experience
Slightly longer latency
Coverage
Spectrum Flexibility
New Spectrum Pricing Because of higher demand FDD has so far
sold for higher $/MHz TDD Spectrum had traditionally auctioned for
lower $/MHz
Coexistence Coexistence requirement for adjacent
frequency in the same geographic area
+
+
+
+
+
Better in big-sized cells + Paired-band is not needed, no duplexing gap +
TTA LTE/MIMO Standards/Technology Training
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Frame Structure
#0 #1 #2 #3 #19
One slot, Tslot = 15360Ts = 0.5 ms
One radio frame, Tf = 307200Ts=10 ms
#18
One subframe
Type 2 for TDD
Type 1 for FDD
One slot,
Tslot=15360Ts
GP UpPTSDwPTS
One radio frame, Tf = 307200Ts = 10 ms
One half-frame, 153600Ts = 5 ms
30720Ts
One subframe,
30720Ts
GP UpPTSDwPTS
Subframe #2 Subframe #3 Subframe #4Subframe #0 Subframe #5 Subframe #7 Subframe #8 Subframe #9
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Frame Structure: FDD/TDD
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TD-LTE: UL/DL configurations
Configuration Switch-point periodicity Subframe number
0 1 2 3 4 5 6 7 8 9
0 5 ms D S U U U D S U U U
1 5 ms D S U U D D S U U D
2 5 ms D S U D D D S U D D
3 10 ms D S U U U D D D D D
4 10 ms D S U U D D D D D D
5 10 ms D S U D D D D D D D
6 5 ms D S U U U D S U U D
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TD-LTE: UL/DL configurations
TTA LTE/MIMO Standards/Technology Training
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* assuming Normal CP
TD-LTE: Special subframe config for max cell range
TTA LTE/MIMO Standards/Technology Training
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Mapping of control channels to TDD config #1
<cf> FDD LTE
TTA LTE/MIMO Standards/Technology Training
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Coexistence among neighboring TDD systems
TTA LTE/MIMO Standards/Technology Training
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Typical RF interference scenario for a TDD
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Coexistence b/w TD-SCDMA and TD-LTE
TTA LTE/MIMO Standards/Technology Training
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Coexistence b/w WiMAX (16e) and TD-LTE
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System Information
• Master information block (MIB) includes the following information:
– Downlink cell bandwidth [4 bit]
– System Frame Number (SFN) except two LBSs
– Etc…
• LTE defines different SIBs:
– SIB1 includes info mainly related to whether an UE is allowed to camp on the cell. This includes info
about the operator(s) and about the cell (e.g. PLMN identity list, tracking area code, cell identity,
minimum required Rx level in the cell, etc), DL-UL subframe configuration in TDD case, and the
scheduling of the remaining SIBs. SIB1 is transmitted every 80ms.
– SIB2 includes info that UEs need in order to be able to access the cell. This includes info about the UL
cell BW, random access parameters, and UL power control parameters. SIBs also includes radio
resource configuration of common channels (RACH, BCCH, PCCH, PRACH, PDSCH, PUSCH,
PUCCH, and SRS).
– SIB3-4 mainly includes info related to cell-reselection.
– SIB5-8 include neighbor-cell-related info. (E-UTRAN, UTRAN, GERAN, cdma2000)
– SIB9 contains a home eNB identifier
– SIB10/11 contains ETWS (Earthquake and Tsunami Warning System) notification
– SIB12: CMAS
– SIB13: eMBMS
– More to be added
• MIB mapped to PBCH, Other SIBs mapped to PDSCH
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Coexistence b/w TDD and FDD
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MIMO Spatial Multiplexing (SM)
Multiple Input Multiple Output (MIMO)
Multiple antennas at both transmitter and receiver
MIMO uses multipath to advantage to “multiply data rate” • Transmits different data along different paths (simplified view)
• MxN MIMO can multiply data rate by M or N (whichever is less) if there is enough multipath. – Best in urban high-multipath environment (and indoors)
– Less effective in suburban and rural low-multipath environments
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How can we get multiplexing?
Simple concept
(1) Transmit “one” data in one link (1 Tx & 1 Rx antenna)
(2) Transmit “two” data in two links far away from each other (1 Tx & 1 Rx antenna, respectively)
(3) Transmit “two” data in one link (1 Tx & 1 Rx antenna) ??
(4) Transmit “two” data in one link (2 Tx & 2 Rx antenna) ??
(4) is just the special case of (2)!!
Simple linear algebra – Matrix (행렬)
– Rank
Favorable channel condition for MIMO SM? – Rich scattering (i.e. multipath) for high rank
– High SINR for reliable decoding
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SVD MIMO as a closed-loop MIMO
?
• In CL-SU-MIMO, SVD-MIMO is the optimum
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MIMO Channel Decomposition
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x~x
V VH U UH
y
minn
1 1~w
min
~nw
Pre-processing Post-processing Channel
),0(~,, 0 r
rt
n
nnNΝCC Iwyx
wHxy
y~
With number of transmitting antenna=nt and receiving antenna=nr,
MIMO Channel Decomposition
TTA LTE/MIMO Standards/Technology Training
38 © Nokia Siemens Networks
wxDy ~~~
wUxD
wxVUDVU
wxUDVU
wHxU
yUy
H
HH
HH
H
H
~
)~(
)(
)(
~
Channel Diagonalization
TTA LTE/MIMO Standards/Technology Training
39 © Nokia Siemens Networks
Codebook for Precoding – 2 ports
• For transmission on two antenna ports, , the precoding matrix shall be selected from Table 6.3.4.2.3-1 or a subset thereof.
1,0p )(iW
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Codebook for Precoding – 4 ports
• The quantity denotes the matrix defined by the columns given by the set from the expression where I is the 4x4 identity matrix and the vector is given by Table 6.3.4.2.3-2.
}{snW }{s
nHn
Hnnn uuuuIW 2
nu
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3GPP Release 8 DL transmission modes Two approaches to multi-antenna transmission
MCS
CQI
PMI
Rank CQI
MCS
PMI
Rank
PDSCH Channel estimation based on common reference signal (CRS)
MIMO Beamforming
PDSCH Channel estimation based on dedicated reference signal (DRS)
CRS DRS
SRS
Closed loop, codebook precoding (TM4) Open loop, non-codebook precoding (TM7)
If UE uses multiple receive antennas, it also has to transmit SRS on multiple antennas in order for UL measurements to fully reflect DL channel state
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• Diversity
– Same data on all the pipes (mode 2)
Increased coverage and link quality
– But, the all pipes can be combined to make a kind-of beamforming
• MIMO
– Different data streams on different pipes (mode 4)
Increased spectral efficiency (increased overall throughput)
Power is split among the data streams
• Beamforming
– Data stream on only the strongest pipe (mode 7)
Utilize different amplitude/phase at all pipes to optimally match per-UE radio condition
Increased coverage and signal SNR
Multi-Antenna Technology Summary
TTA LTE/MIMO Standards/Technology Training
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3GPP Release 9/10 DL transmission modes Enhanced beamforming: dual-layer beamforming (TM8) Multi-layer (TM9)
With cross polar antennas in mind TDD operators have been eager to extend Rel8 Beamforming to support two streams.
Spatial multiplexing supported
- Up to 2 layers per user (SU-MIMO)
- Up to 4 layer in total (MU-MIMO)
CRS based PMI and rank reporting supported for beamforming
- Similar feedback schemes as for Rel-8 SU-MIMO (tx-mode 4)
- TxD CQI also supported
- One CRS per polarization via sector beam virtualization (as in Rel-9)
CQI
PMI
Rank
MCS
Rank
PDSCH Channel estimation based on DRS
DRS
SRS
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PDSCH Transmission Modes
Mode Details
1 Single-antenna transmission
2 Transmit diversity
3 Open-loop codebook-based precoding in the case of more than one layer, transmit diversity in the case of rank-one transmission
4 Closed-loop codebook-based precoding
5 Multi-user-MIMO version of transmission mode 4
6 Special case of closed-loop codebook-based precoding limited to single-layer transmission
7 Release-8 non-codebook-based precoding supporting only single-layer transmission
8 Release-9 non-codebook-based precoding supporting up to two layers
9 Release-10 non-codebook-based precoding supporting up to eight layers
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Cell-Specific RS Mapping
Normal CP Extended CP
1 Tx ant 4.76% 5.56%
2 Tx ant 9.52% 11.11%
4 Tx ant 14.29% 15.87% 0l
0R
0R
0R
0R
6l 0l
0R
0R
0R
0R
6l
On
e an
ten
na
po
rtT
wo
an
ten
na
po
rts
Resource element (k,l)
Not used for transmission on this antenna port
Reference symbols on this antenna port
0l
0R
0R
0R
0R
6l 0l
0R
0R
0R
0R
6l 0l
1R
1R
1R
1R
6l 0l
1R
1R
1R
1R
6l
0l
0R
0R
0R
0R
6l 0l
0R
0R
0R
0R
6l 0l
1R
1R
1R
1R
6l 0l
1R
1R
1R
1R
6l
Fo
ur
ante
nn
a p
ort
s
0l 6l 0l
2R
6l 0l 6l 0l 6l
2R
2R
2R
3R
3R
3R
3R
even-numbered slots odd-numbered slots
Antenna port 0
even-numbered slots odd-numbered slots
Antenna port 1
even-numbered slots odd-numbered slots
Antenna port 2
even-numbered slots odd-numbered slots
Antenna port 3
RS Overhead
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UE-specific RS (R5) on top of CRS
• UE-specific RS (antenna port 5)
– 12 symbols per RB pair
• DL CQI estimation is always based on cell-specific RS (common RS)
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New DM-RS for scalability
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• Diversity
– Same data on all the pipes (mode 2)
Increased coverage and link quality
– But, the all pipes can be combined to make a kind-of beamforming
• MIMO
– Different data streams on different pipes (mode 4)
Increased spectral efficiency (increased overall throughput)
Power is split among the data streams
• Beamforming
– Data stream on only the strongest pipe (mode 7)
Utilize different amplitude/phase at all pipes to optimally match per-UE radio condition
Increased coverage and signal SNR
– Not any more focusing on the strongest pipe in transmission mode 8 in R9 and mode 9 in R10
Multi-Antenna Technology Summary
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LTE FDD vs TD-LTE link budget comparison (700MHz example)
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3GPP Defined LTE CA Band Combinations
Release 10 • Band1 + Band5 LG U+
Release 11 Work Items • LTE_CA_B1_B7: LTE Advanced Carrier Aggregation of Band 1 and Band 7
• LTE_CA_B1_B18: LTE Advanced Carrier Aggregation of Band 1 and Band 18
• LTE_CA_B1_B19: LTE Advanced Carrier Aggregation of Band 1 and Band 19
• LTE_CA_B1_B21: LTE Advanced Carrier Aggregation of Band 1 and Band 21
• LTE_CA_B2_B17: LTE Advanced Carrier Aggregation of Band 2 and Band 17
• LTE_CA_B3_B5: LTE Advanced Carrier Aggregation of Band 3 and Band 5 SK Telecom
• LTE_CA_B3_B7: LTE-Advanced Carrier Aggregation of Band 3 and Band 7
• LTE_CA_B3_B8: LTE-Advanced Carrier Aggregation of Band 3 and Band 8 KT
• LTE_CA_B3_B20: LTE Advanced Carrier Aggregation of Band 3 and Band 20
• LTE_CA_B4_B5: LTE Advanced Carrier Aggregation of Band 4 and Band 5
• LTE_CA_B4_B7: LTE Advanced Carrier Aggregation of Band 4 and Band 7
• LTE_CA_B4_B12: LTE Advanced Carrier Aggregation of Band 4 and Band 12
• LTE_CA_B4_B13: LTE Advanced Carrier Aggregation of Band 4 and Band 13
• LTE_CA_B4_B17: LTE Advanced Carrier Aggregation of Band 4 and Band 17
• LTE_CA_B5_B12: LTE Advanced Carrier Aggregation of Band 5 and Band 12
• LTE_CA_B5_B17: LTE Advanced Carrier Aggregation of Band 5 and Band 17
• LTE_CA_B7_B20: LTE Advanced Carrier Aggregation of Band 7 and Band 30
• LTE_CA_B8_B20: LTE Advanced Carrier Aggregation of Band 8 and Band 20
• LTE_CA_B11_B18: LTE Advanced Carrier Aggregation of Band 11 and Band 18
• LTE_CA_B7: LTE Advanced Carrier Aggregation in Band 7
• LTE_CA_B25: LTE Advanced Carrier Aggregation Intra-Band, Non-Contiguous in Band 25
• LTE_CA_B38: LTE Advanced Carrier Aggregation in Band 38
• LTE_CA_B41: LTE Advanced Carrier Aggregation in Band 41
* CA Band Combination은 사업자의 요구에 따라 지속적으로 늘어남
CA for TD-LTE
Carrier aggregation is supported for both FDD and TDD, although all component carriers need to have the same duplex scheme.
In the case of TDD, the uplink–downlink configuration should be the same across component carriers.
The special subframe configuration can be different for the different components carriers though, as long as the resulting downlink–uplink switch time is sufficiently large.
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HARQ Retransmission Timing
• Acknowledgement of a transport block in subframe n is transmitted in subframe n + k , where k ≧ 4 and is selected such that n + k is an uplink subframe
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HARQ Acknowledgement Bundling
• For DL transmissions, there are some configurations where DL-SCH receipt in multiple DL subframes needs to be acknowledged in a single UL subframe
– Multiplexing
Independent acknowledgements for each of the received transport blocks are fed back to the eNodeB. This allows independent retransmission of erroneous transport blocks. However, it also implies that multiple bits need to be transmitted from the terminal.
– Bundling of acknowledgements
The outcome of the decoding of DL transport blocks from multiple DL subframes can be combined into a single hybrid-ARQ acknowledgement transmitted in UL. Only if both of the DL transmissions in subframes 0 and 3 in the example below are correctly decoded will a positive acknowledgement be transmitted in UL subframe 7.
The downlink assignment index in the scheduling assignment on the PDCCH is used to avoid confusion
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UL Grant Timing
• For TDD configurations 1–6, the uplink transmission occurs in subframe n + k , where k is the smallest value larger than or equal to 4 such that subframe n + k is an uplink subframe.
• For TDD configuration 0 there are more UL subframes than DL subframes, which calls for the possibility to schedule transmissions in multiple UL subframes from a single DL subframe. For DL-UL configuration 0, the index field specifies which UL subframe(s) a grant received in a DL subframe applies to.
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Random Access
• Short PRACH preamble (format 4) only for TD-LTE (to utilize UpPTS in small cells)
• For TDD, multiple random-access regions can be configured in a single subframe.
The reason is the smaller number of uplink subframes per radio frame in TDD. To
maintain the same random-access capacity as in FDD, frequency-domain
multiplexing is sometimes necessary.
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Better Utilization of SRS
• SRS (Sounding Reference Signal)
– SRS can be used for both DL beamforming and UL CAS
• Calibration needed for channel reciprocity
Model to illustrate the impact from RF units to channel reciprocity (capital letters indentify matrixes)
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FDD-TDD Handover
FDD - TDD mobility
• Network controlled
• Event triggered based on DL measurement RSRP and RSRQ
• Inter frequency measurements triggered by events A1/A2
• Configurable thresholds for
coverage based (A5),
best cell based (A3) handover
MME S-GW
TTA LTE/MIMO Standards/Technology Training
57 © Nokia Siemens Networks
TD-LTE is IMT-Advanced approved too!
TTA LTE/MIMO Standards/Technology Training
58 © Nokia Siemens Networks
TD-LTE is IMT-Advanced approved too!
TTA LTE/MIMO Standards/Technology Training
59 © Nokia Siemens Networks
TD-LTE Summary
• Market potential
• High level of commonality b/w FDD LTE and TD-LTE
• Slight difference in frame structure (FDD vs. TDD)
• Time synchronized network
• Need to ensure coexistence b/w neighboring TDD systems
• Better beamforming performance with channel reciprocity
• Smaller link budget which fits to capacity networks
• Flexible DL/UL capacity for various applications
TTA LTE/MIMO Standards/Technology Training
60 © Nokia Siemens Networks
Thank you !
www.nokiasiemensnetworks.com
Nokia Siemens Networks
20F, Meritz Tower, 825-2
Yeoksam-Dong, Kangnam-Gu
Seoul 135-080, Korea
Bong Youl (Brian) Cho Lead Product Manager Korea, Ph.D.
LTE Business Line, MBB
brian.cho@nsn.com
Mobile 010-4309-4129
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