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MIMO-LTE A relevant Step
towards 4GProf. Dr.-Ing. Thomas Kaiser
CEO
mimoOn GmbH
MobiMedia, August 27-29, 2007
2 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
mimoOn is …
… a supplier of embedded communications software for the next generation of MIMO-based wireless communication standards.
Check www.mimoOn. deSept. 11-14, 2007:
• MIMO-Workshop• MIMO Seminar• LTE Seminar
3 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
Edholm’s law of data rate:
What means “4G” ?
Magic Mobile Future Study: >2 GHz BW in 2020
OFDM will comeMIMO will come
4 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
The Future of MIMO
High-speed mobile access requires “MIMO” …
201520102005200010 kb/s
100 kb/s
1 Mb/s
10 Mb/s
100 Mb/s
1000 Mb/s
GSM
GPRS
EDGE
UMTS
1xEV-DO
HSPA
MIMO-WiMAXMIMO-LTE
MIMO- .16m
MIMO-…
5 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
The History of MIMO
1987 1st MIMO paper (Winters)
1991 1st MIMO patent (Paulraj) 1995 MIMO channel capacity (Telatar, Foschini, Gans)1996 1st MIMO testbed
1999 1st MIMO prototype chip2002 1st MIMO company2005 1st MIMO commerc. chip2006 MIMO breakthrough
6 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
MIMO Principles
Array Gain: +3dB p.D. for SIMO, MISO (PCSI), MIMO (PCSI))Diversity Gain: +XdB for SIMO, MISO, MIMO (CSI helps)Interf. Cancell. Gain: Nulling for SIMO, MISO, MIMO (all PCSI)Multiplexing Gain: for MIMO (CSI helps)
… MISO
… MIMO
… SISO
Challenge: “Gain” Tradeoff’s under Hardware, Regulation, and Standardization Constraints
7 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
Separate Frequency Flat Channels
Tx Rx
8 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
Equivalent Parallel Channels
Equivalent channel
9 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
Open Loop vs. Closed Loop
Tx Rx
Closed Loop: (Diversity order max. )
Challenge: Low rate feedback, high mobility
10 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
MIMO-LTE Transmitter (DL)
# of modulated codewords per
subcarrier
Tx1
# of layers# of Tx
# of subcarriers
one resource block
LayerMapping
LayerMapping
LayerMapping
LayerMapping
common H1
Diversity
Precoder P1
cyclic delay
Precoder P1
cyclic delay
LayerMapping
LayerMapping
LayerMapping
LayerMapping
common HL
Precoder PL
cyclic delay
Precoder PL
cyclic delay
Tx1IFFTaddCP
Tx2IFFTaddCP
Tx3IFFTaddCP
Tx4IFFTaddCP
Tx2 Tx3 Tx4
Diversity
Diversity
Diversity
subcarrier 1
subcarrier K
subcarrier N
11 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
MIMO-LTE Receiver (DL)
# of layers# of Rx# of code-words
(CW) per subcarrier
one resource block
common H1
B1
ReceiveBeamformer
B1
ReceiveBeamformer
Rx1FFTremCP
Rx2FFTremCP
Rx3FFTrem.CP
Rx4FFTrem.CP
(ST)-MIMO Detector
BL
ReceiveBeamformer
BL
ReceiveBeamformer
(ST)-MIMO Detector
common HL
(ST)-MIMO Detector
(ST)-MIMO Detector
(ST)-MIMO Detector
(ST)-MIMO Detector
(ST)-MIMO Detector
Rx1
Rx2
Rx3
Rx4
# of subcarrier
Detection: ~(#CW)2 x MR x
1200 MAC / (0.5ms/7) = (#CW)x
(#CW+MR)x16,8 MMACps
# of subcarrer
(#antennas) x 210 x 11 x 4/(0.5 / 7)ms =
(#antenna) x 630 MMACps
channel update: (once per RB) ~ 1200 / 12 /
0.5ms x MR x MT
2 MAC= 0.2 x MR
x MT2
MMACps
12 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
MIMO-LTE Algorithms
Challenge: MIMO Detector
• No. of Antennas ?
• X-QAM ?
• Hard/Software ?
13 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
MIMO-LTE Receive Chain Requirements
RF Freq Offs Correction
Cycl Prfx Remove FFT
Freq Offs Estimation
Synchroni-zation
De-mux
Chan Est MIMO Detector
30.72 MCSps(1.47 Gbps)
28.67 MCSps(1.38 Gbps)
16.8 MCSps(538 Mbps)
Rx1
Rx2
Data / Rxbps with Rx=2
50 Mbps(100 Mbps)
Data / Txbps with Tx=2
16.8 MSps(300 Mbps)
100 Msbps(600 Mbps)
100 Mbps
123 MMACps(246 MMACps)
Symbol Demapper
De-Inter-leaver
Channel DecoderM
UX
RF Freq Offs Correction
Cycl Prfx Remove FFT De-
mux
269 - 538 MMACps
Symbol Demapper
De-Inter-leaver
Channel Decoder
76.8 GACSps(153.6 GACSps)
2x12 2x10
9
3
CSps: Complex Sample per secondSbps: soft bits per second
#Rx = 2#Tx = 2
MAC: Multiply AccumulateACS: Add Compare Select
CSps: Complex Sample per secondsbps: soft bits per second MAC: Multiply AccumulateACS: Add Compare Select
631 MMACps(1262 MMACps)
No ML algorithmfor 64QAM
Configuration: 2 Rx, 2 Tx, 64QAM, 100 Mbps data rate, Turbo Coding 1/3,
14 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
Some Results: MIMO-OFDMA
1134
0.20Ratio of Users among CoveredUsers 0.15
0.10
0
4536 9072 13608
Net data rate in kb/s
2x3 MIMO-OFDMAReuse=1, TX=10W, Isolated Cell2MHz BandwidthSpatial Mux with 64 QAM (equiv. 4096 SISO-QAM)12dB better link budget than for SISOIospan Wireless, San Jose Testbed, 2001Thanks to Prof. A. Paulraj (Stanford Univ.)
15 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
Some Results: Cellular MIMO
Challenge: MIMO-Algorithm Design
2
bit
/s/
Hz
0
Peak rate
Mean rate
Cell edge rate
1
SISO 2x2 MIMO
Isolated CellSISO 2x2 MIMO
Interf. Lim. Cell
Sourc
e: 3
G a
mer
icas,
„M
obile
Bro
adban
d:
The
Glo
bal
Evo
lution o
f U
MTS/H
SPA
“, D
ec 1
4,
2006
16 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
MIMO-Femtocell-Scenario
MIMO is well-suited for “contained” environments100 Mbit/s feasible with femtocellsMIMO-Femtocells similar to MIMO-WLAN
17 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
MIMO 2x2 SISO
Source: „Throughput of a MIMO OFDM based WLAN system“, T. Schenk et. al., IEEE SCVT2004, Gent, Belgium, Nov. 2004
MIMO-LTE vs MIMO-WLAN
30 m ~ 100 m2.8 km ~ 7.4 km Coverage
< 5 ms10 msLatency (round trip)
> 200 Mbps100 (DL) / 50 (UL) Mbps
Theoretical peak bit rate in ideal case
Weak supportGood supportQoS
CSMA/CAOFDMAAccess technology
64 /312.5 kHz
128 ~ 2048 /15 kHz
FFT and Subcarrier Spacing
Packet data
Fixed20 MHz
SFBC, SM, Beamforming
OFDM
pre802.11n
Packet data, VoIPServices
Scalable1.25 ~ 20 MHz
System Bandwidth
SFBC, SM, BeamformingMIMO mode
OFDMModulation technique
MIMO preLTE
18 / 18“MIMO-LTE – A relevant step towards 4G”, Thomas Kaiser, MobiMedia, August 27-29, 2007
Conclusion
… to increase user capacity… to increase coverage… to increase cell throughput
MIMO represents an economical way to
“… the potential of using the spatial domain is large and the development of new and even more efficient multi-antenna algorithms is expected to continue in the future.”
Source: 3G americas, „Mobile Broadband: The Global Evolution of UMTS/HSPA“, Dec 14, 2006