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B3G and MIMO MC-CDMA B3G and MIMO MC-CDMA
Speaker : Pei-Yun TsaiAdvisor : Tzi-Dar Chiueh
2005/04/25
2
OutlineOutline
• Beyond 3G– Evolution– Main Features– Possible Techniques
• MIMO MC-CDMA – From SISO to MIMO– Synchronization– Channel estimation– MIMO decoding
• Conclusion
Beyond 3GBeyond 3G
4
Evolution of Mobile SystemsEvolution of Mobile Systems
[1]
2010
5
Main Features of B3GMain Features of B3G
• Frequency efficiency up to 10 b/s/Hz [2] • Flexible radio resource management [2]
– Enlarge the coverage– Improve system efficiency
• Supporting IPv6 multimedia services with [2]– Low transmission power (10dB lower than 3G)– Eb/N0 less than 3dB at bit error rate of 10-6 for 100 Mb/s.
• Supporting vehicular speed of 250 km/hr [2]• Entirely packet-switch services [3]
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Possible Techniques –Possible Techniques – Radio Transmission Radio Transmission
• Modulation [2] – OFDM– Robustness against frequency-selective fading channels in wid
e bandwidth– Efficient spectrum utilization– Flexibility in subcarrier allocation– Adaptability in subcarrier modulation
• In 3GPP [4],– Feasibility study of OFDM
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Possible Techniques –Possible Techniques – Radio Transmission Radio Transmission
• Multiple access scheme [5] – CDMA– Greater coverage with fewer cell sites – Better frequency reuse– Higher capacity
• In IMT-2000 family, four out of five systems use CDMA techniques.
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Possible Techniques –Possible Techniques – Radio Transmission Radio Transmission
• Advanced detection techniques [6] – Multiuser detection (MUD) techniques
• MAI• Near-far effect
– Linear receiver• MMSE
– Interference canceller (Widely considered)
• Parallel IC (PIC)• Successive IC (SIC)• Selective PIC (SPIC)
– Turbo MUD– Adaptive detector
Received Signal
Combining
Informative Bit
Decision
> Threshold
Reliable Signal
Cancellation
Combining
Informative Bit
DecisionSPIC
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Possible Techniques –Possible Techniques – Radio Transmission Radio Transmission
• MIMO techniques [8]– Providing spatial diversity
• STBC– Achieve better QoS for average data rate
• STTC– High complexity
– Increase frequency efficiency• BLAST
– The number of receive antennas is greater than or equal to the number of independent transmit signals.
– Poor detection performance over spatially correlated channel.– Exploit knowledge of channel to provide capacity gain
• SVD
• MIMO may be implemented in HSDPA.
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Possible Techniques –Possible Techniques – Radio Transmission Radio Transmission
• MIMO comparison[8]
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Possible Techniques –Possible Techniques – Link Layer Link Layer
• Adaptive modulation and coding techniques (AMC) [6]– Adapt transmission parameters to take advantage of
channel conditions.– Increase spectral efficiency.– Also power level, spreading factors, signal bandwidth, and
etc. can be adjusted.
• Considered in HSDPA and GPRS.
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Possible Techniques –Possible Techniques – Resource Management Resource Management
• Radio resource management (RRM)– Admission control (AC)
• Reject new connection if causing unacceptable degradation– Power control
• Minimize power consumption– Scheduling
• Priority-based management
MIMO MC-CDMAMIMO MC-CDMA
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ConsiderationConsideration
• MIMO techniques– STBC– V-BLAST
• MIMO decoding– Noise– Multiple access interference (MAI)– Inter antenna interference (IAI)
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MIMO MC-CDMA ReceiverMIMO MC-CDMA Receiver
• Synchronization blocks are shared.• JWLS estimation, channel estimation, and
combining strategies are different from SISO version.
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Hardware RequirementHardware Requirement
• Derotator x 2• FFT x 2• Channel estimation x 4• Equalizer (FEQ) x 4 (More complicated)• Despreading x 4• SRAM for channel Respon
se x 4• EQ data delay buffers x 4• Channel estimates delay b
uffers x4• Additional data buffers (N) x 2
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JWLS Estimation (1/2)JWLS Estimation (1/2)
• Estimation for residual CFO and TFO– Alternative pilot data are transmitted by antenna 1.– Simple solution: using pilot data separated by 2 symbols
Antenna 0 Antenna 1
Training symbol 0Training symbol 1Data symbol 0Data symbol 1
AWGNICIHAHAZ kkkkik ,10,00,
AWGNICIeHAHAZk
NN
jkkkkik
T
)(
22
,10,002, )(
...)|||(|||)(
222
,102
,002*
,2,
k
NN
jkkkikik
T
eHHAZZ
Data symbol 2
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JWLS Estimation (2/2)JWLS Estimation (2/2)
• Performance can be improved in the MIMO receiver due to increase of SINR.
...)|||(|||)(
222
,102
,002*
,2,
k
NN
jkkkikik
T
eHHAZZ
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Channel EstimationChannel Estimation
• Same performance as in the SISO cases at the same transmitted power.– LS channel estimation– Frequency-domain channel interpolation
0,
1010000, ikkkkkik vHAHAZ
1,
1110101, ikkkkkik vHAHAZ
0
01,
0,00
0
01,
0,00
22ˆ
k
ikikk
k
ikikk
A
vvH
A
ZZH
k
kk
k
kk A
vH
A
ZH ˆ
01,
10100001, ikkkkkik vHAHAZ
11,
11101011, ikkkkkik vHAHAZ
MIMOSISO
kkkk vHAZ
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Review of SUD in SISO MC-Review of SUD in SISO MC-CDMACDMA
• Single user detection [9]– MRC : maximize SNR
– EGC : no optimization
– ORC : reduce MAI
– MMSEC (per subcarrier): reduce MAI and noise
– TORC : combine EGC and ORC
*kk HG
||
*
k
kk H
HG
2
*
|| k
kk
H
HG
)/(|| 22
*
usk
kk
NEH
HG
thresholdH
thresholdH
HH
HHG
k
k
kk
kkk
||
||
||/
||/2*
*
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MIMO Processing MIMO Processing - STBC (1/2)- STBC (1/2)
• Consider SUD– Apply TORC to reduce MAI, inter-antenna interference
(IAI), and noise0,,
10,,
00,
0, ik
uLlukku
ulukkuik vdHcdHcZ
11,
*,
10,
*,
00,
01, ik
ulukku
uLlukkuik vdHcdHcZ
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MIMO Processing MIMO Processing - STBC (2/2)- STBC (2/2)
• Apply MRC.
• Consider orthogonality restoring to reduce MAI.
• Avoid noise enhancement like TORC.
termnoisedcHHZHZHWu
lukukkikkikkik ,,201200*0
1,100
,*000
, )|||(|)()(
termnoisedccWcHH
du
lukuk
kikk
kkk
l
,,,00,,0201200,0
)|||(|
1ˆ
Gk
thresholdHH
HH
thresholdHHHH
G
kkkk
kkkk
k201200
201200
201200201200
||||)|||(|
1
||||||||
1
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Conclusion and Future WorkConclusion and Future Work
• The current status of B3G is introduced. – Possible features and techniques are discussed.
• Our MIMO MC-CDMA is examined. – Consider the hardware requirement, the synchronization
block the channel estimation block and MIMO decoding.
• Future work --– BER comparison between the SISO MC-CDMA and MIMO
MC-CDMA.
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ReferenceReference
[1] B. Li and et al., ’’Recent advances on TD-SCDMA in China,’’ IEEE Communications Magazine, vol. 1, pp. 30-37, Jan. 2005.
[2] P. Zhang and e. al., ’’A vision from the future: beyond 3G TDD,’’ IEEE Communications Magazine, vol. 1, pp. 38-44. Jan. 2005.
[3] http://users.ece.gatech.edu/~jxie/4G/[4] 3GPP, Technical Specification Group Radio Access Network, Feasibility study for orthogoanl frequency d
ivision multiplexing (OFDM) for UTRAN Enhancement, TR 25.892, V6.0.0 (2004-06).[5] A. Jamalipour and et al., ’’ A tutorial on multiple access technologies for beyond 3G mobile networks,
’’ IEEE Communications Magazine, vol. 2, pp.110-117, Feb. 2005.[6] R. Fantacci and et al., ’’Perspectives for present and future CDMA-based communications systems,’
’ IEEE Communications Magazine, vol. 2, pp. 95-100, Feb. 2005.[7] K. Zheng and et al.,’’TD-CDM-OFDM: evolution of TD-SCDMA toward 4G,’’IEEE Communications Ma
gazine, vol. 1, pp. 40-52, Jan. 2005.[8] H. Yang,’’A road to future broadband wireless access: MIMO-OFDM-based air interface,’’IEEE Com
munications Magazine, vol. 1, pp. 53-60, Jan. 2005.[9] R. Le Gouable and M. Helard,’’Performance of single and multi-user detection techniques for a MC-C
DMA system over channel model used for HIPERLAN2,’’ IEEE International Symposium on2000 IEEE Sixth Spread Spectrum Techniques and Applications, Parsippany,New Jersey, Sep. 2000, pp. 718-722.