Overview of AMC LTE feature to enhance DL user througput.

Overview of AMC LTE feature to enhance DL user througput.

1. Overview of AMC in LTE
Gwanmo Ku
Adaptive Signal Processing and Information Theory Research Group
Jun. 15, 2012

2. Outline
LTE Basic
Why LTE
LTE Network / Resources / Frame Structure
LTE in US (Verizon)
AMC in LTE
Why AMC?
Channel Condition : CQI Reporting
MCS associated with CQI
References
2/17

3. LTE Basic
2/11

4. Why LTE?




4/17
Higher Data Rate
QoS
Packet Switch
Optimized System
Continuity of
Competitiveness
of 3G System
High Spectral Efficiency
Very Low Latency
Support of Variable Bandwidth
LTE
(Reference: http://www.3gpp.org/LTE)

5. LTE Network



5/17
 LTE Network











Internet
* EPC : Evolved Packet Core
* E-UTRAN : Evolved Universal Terrestrial Radio Access Network
* UE : User Equipment
* eNB : evolved Node B

6. LTE Resource (Unit)




6/17
 Physical Resource Block (PRB)
 The Smallest User Assignment Resource Unit (12 Sub-carriers)
Frequency
(#Subcarriers)
Time
(# Symbols)
180 KHz
(12 Sub-carriers)
0.5 ms
(6 or 7)
PRB

7. LTE Resource (Parameters)
DL/UL Parameters








Subcarrier Spacing ∆??????=15 ?????????????????? UL/DL, ∆??????
∗
=7.5 ?????????????????? DL only
Parameters used by Verizon in US
7/17
System BW [MHz] 1.4 3 5 10 15 20
# Resource Blocks ??????
???????????? 6 15 25 50 75 100
FFT Size ??????
∆??????=?????????????????????????????? 2048
∆??????=??????.???????????????????????? - 4096*
# Subcarriers per RB ??????
????????????
∆??????=?????????????????????????????? 12
∆??????=??????.???????????????????????? - 24*
# Used Subcarriers ??????
??????
∆??????=?????????????????????????????? 72 180 300 600 900 1200
∆??????=??????.???????????????????????? - 2400*
Sampling Rate [MHz] 30.72
(Reference : 3GPP TS 36.101 V8.15.0 (2011-09))

8. LTE Frame Structure
Frame Structure Type 1 : FDD


Frame Structure Type 2 : TDD

8/17
5ms
Switch
10ms
Switch
(Reference : 3GPP TS 36.211 V8.9.0 (2009-12))

9. LTE Service in US (Verizon)




9/17
 LTE Operating Band (Verizon)





 BW 10 MHz, 600 Sub-carriers (50 PRBs)
MHz 699 716 729 746 756 758 768 777 787 788 798
700 800
750
Band 13 Band 13
Verizon LTE Plan in US
FCC Upper 700 MHz Block C
FDD Uplink FDD Downlink
E-UTRA LTE Band
FCC Band in US
C C
757 776

10. Adaptive Modulation & Coding
2/11

11. Why AMC?


11/17
 Needs in Communication
System Throughput













User Data Rate
User Low BER
Resource Assignment
Adaptive Modulation & Coding
Higher Order Modulation
Larger TBS
Lower Order Modulation
AMC
&
RM

12. Adaptive Modulation & Coding


12/17
 Modulation Order & BER (without channel coding)



 Channel Coding : Better BER
 Rate Change by Rate Matching
 Better Data Rate

BPSK QPSK 16QAM 64QAM
Better Throughput / Data Rate
Bad BER

13. Channel Condition


13/17
 CQI Reporting Process
eNB
UE
DL Reference Signals
CQI Reporting
Scheduling Information
-Allocated Bands
-MCS / TBS
4 bit CQI
Indexing

14. CQI Table


14/17
 4-bit CQI Table
CQI Modulation Spectral Efficiency
0 Out of Range
1
QPSK
0.1523
2 0.2344
3 0.3770
4 0.6016
5 0.8770
6 1.1758
7
16 QAM
1.4766
8 1.9141
9 2.4063
10
64 QAM
2.7305
11 3.3223
12 3.9023
13 4.5234
14 5.1152
15 5.5547
Spectral Efficiency
Throughput
�??????=??????⋅�(�??????�)
��??????�=log
21+�??????� [bps/Hz]
?????? : Practical Attenuation Factor

15. MCS associated with CQI


15/17
 5-bit MCS
MCS CQI Modulation Spectral Efficiency MCS CQI Modulation Spectral Efficiency
0 2
QPSK
0.2344 16 16QAM 2.5684
1 0.3057 17
64 QAM
2.5684
2 3 0.3770 18 10 2.7305
3 0.4893 19 3.0264
4 4 0.6016 20 11 3.3223
5 0.7393 21 3.6123
6 5 0.8770 22 12 3.9023
7 1.0264 23 4.2128
8 6 1.1758 24 13 4.5234
9 1.3262 25 4.8193
10
16 QAM
1.3262 26 14 5.1152
11 7 1.4766 27 5.3349
12 1.6953 28 15 5.5547
13 8 1.9141 29 QPSK
Reserved 14 2.1602 30 16QAM
15 9 2.4063 31 64QAM

16. References
2/11

17. References
•LTE related Webpages
http://www.3gpp.org : 3GPP Standard Web
http://www.fcc.gov/ : FCC
http://wireless.fcc.gov/uls/ : FCC Band License Search
• LTE Standard Docs.
 http://www.3gpp.org/ftp/Specs/latest/Rel-8/36_series/
17/17