0. Applications of MIMO 최 수 용 csyong@yonsei.ac.kr
연세대학교 전기전자공학과

1. Vertical/Horizontal MIMO
Vertical Encoded 2x2 MIMO System
= Single CodeWord MIMO (SCW MIMO)
Horizontal Encoded 2x2 MIMO System
= Multiple Codeword MIMO (MCW MIMO) : MU-MIMO
같은 FEC 및 modulation
Uplink? Downlink?
Antenna 마다 다른 FEC 및 modulation

2. SFBC
STBC (Space Time Block Code)
SFBC (Space Frequency Block Code)

3. Cyclic Delay Diversity (CDD)
3GPP Release 8 LTE 표준
채널의 심한 변화
Scattered frequency selective fading
주파수 영역에서 인터리빙
주파수 코딩 이득 증대
Burst frequency selective fading

4. 다중반사파에대한이동통신기술의진화

5. AMS (Adaptive MIMO Switching)
CQI (Channel Quality Index) : AMC
PMI (Precoding Mapping Index) : Precoder
RI (Rank Index) : Number of stream

6. MIMO 기법 Open/closed loop MIMO
Multicell MIMO, COMP(cooperative multi-point Tx & Rx) – LTE-A

7. R8 LTE MIMO Design Principles
Anti-fading: TD(Transmit diversity) (and SM)
Enhance spectral efficiency: SM (TD and BF)
Enhance SNR: BF (and codebook-based precoding)
Channel adaptive: CL precoding, Rank adaptation

8. R8 LTE MIMO Summary (Precoding vector switching)
(Time switched transmit diversity)
(Frequency switched transmit diversity)
(Demodulation)

9. LTE 물리채널별 MIMO 기술 Physical channel Usage Tx Diversity SM-MIMO CDD
Reference Signal X
Primary, & Secondary Synch Signal
Physical Broadcasting Channel
System information (Master information Block) O
Physical Control Format Indication Channel
Control Format Indicator( Subframe마다 전송, OFDM symbol 수)
Physical Downlink Control Channel
자원할당, HARQ 및 scheduling 정보
Physical Multicast Channel
방송형 data
Physical Downlink Shared Channel
Downlink user data

10. LTE DL Reference Signals Mapping

11. SFBC+FSTD
When the pilot density is same for data transmitted on four antennas
When the pilot density for data transmitted on different antennas is not same, e.g. pilot density on group 1 (antenna 1 and 2) is not same with that on group 2 (antenna 3 and 4)
When the pilot density is all different for antenna 1,2, 3 and 4

12. DL Physical Channel Processing
Scrambling of coded bits in each of the code words to be transmitted on a physical channel
Modulation of scrambled bits to generate complex-valued modulation symbols
Mapping of the complex-valued modulation symbols onto one or several transmission layers
Precoding of the complex-valued modulation symbols on each layer for transmission on the antenna ports
Mapping of complex-valued modulation symbols for each antenna port to resource elements
Generation of complex-valued time-domain OFDM signal for each antenna port
*3GPP TS , Evolved Universal Terrestrial Radio Access (E-UTRA); physical Channels and Modulation, V8.6.0, March 2009

13. Layer Mapping for SM

14. Precoding for large-delay CDD

15. RI, PMI, CQI Rank Indication (RI) Precoder Matrix Indication (PMI)
Inform about the channel rank or, expressed differently, the number of layers
Precoder Matrix Indication (PMI)
Provides a precoder matrix that should, preferably, used for DL transmission
The reported precoder matrix should be determined assuming the number of layers indicated by RI
PMI is reported only in CL mode. In OL mode, the network instead selects the precoder matrix to use according to a pre-defined rule.
Network has 2 choices:
The network may follow the recommendation from UE, in which case it only has to confirm with 1 bit indicator in DL scheduling assignment.
The network may select a different precoder. Then the precoder information needs to be explicitly included in DL scheduling assignment.
Channel Quality Indication (CQI)
A set of pre-defined MCS combinations

16. 7 Tx modes are possible in PDSCH
Transmission Mode 1
한 개의 안테나를 통한 전송
Transmission Mode 2
Tx Antenna Diversity
Alamouti Coding
SFBC for 2 Tx antenna
FSTD for 4 Tx antenna
Transmission Mode 3
Open loop SM-MIMO
Transmission Mode 4
Closed loop SM-MIMO
CQI, PMI, RI feedback from UE
Transmission Mode 5
MU-MIMO
Transmission Mode 6
Closed loop Beam Forming
Closed loop rank 1 precoding
Transmission Mode 7
Open loop Beam Forming
UE-specific Reference signal

17. 7 Tx modes are possible in PDSCH
Mode 1 : Single-antenna port; port 0
DL transmissions using a single Tx antenna at eNB :일반적인 SIMO 전송
Mode 2: Transmit diversity
DL transmission using Alamouti-like transmit diversity schemes (SFBC)
The number of layer is equal to the number of antenna ports

18. 7 Tx modes are possible in PDSCH
Mode 3: Open loop spatial multiplexing
Transmit different streams of data simultaneously on the same RB(s) by exploiting the spatial dimension of the radio channel. These data streams belong to the same user
Up to 2 codewords transmissions with “no PMI feedback”
Exploits CDD in DL transmissions
Up to 4 layers and 4 antennas

19. 7 Tx modes are possible in PDSCH
Mode 4: Closed loop spatial multiplexing (SU-MIMO)
Transmit different streams of data simultaneously on the same RB(s) by exploiting the spatial dimension of the radio channel. These data streams belong to the same user.
Up to 2 codewords transmissions with “RI and PMI feedback”
Exploits CDD in DL transmissions
Up to 4 layer and 4 antennas

20. 7 Tx modes are possible in PDSCH
Mode 5: Multi-user MIMO (MU-MIMO)
Transmit different streams of data simultaneously on the same RB(s) by exploiting the spatial dimension of the radio channel. These data streams belong to different users.
Also known as downlink SDMA
Single codewords and single Layer per user (UE reports only PMI, no RI is reported)
Up to 4 Tx antennas at eNB

21. 7 Tx modes are possible in PDSCH
Mode 6: Closed loop Rank=1 precoding
Same as Mode 4 with Rank restriction 1
No Rank reports are required
Mode 7: Single antenna port; port5
Same as Mode 1 using UE-specific Reference Signals instead of Cell-specific Reference Signals (with the help of sounding reference signal)