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]

6

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

7

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.

8

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

9

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.

10

Possible Techniques –Possible Techniques – Radio Transmission Radio Transmission

• MIMO comparison[8]

11

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.

12

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

14

ConsiderationConsideration

• MIMO techniques– STBC– V-BLAST

• MIMO decoding– Noise– Multiple access interference (MAI)– Inter antenna interference (IAI)

15

MIMO MC-CDMA ReceiverMIMO MC-CDMA Receiver

• Synchronization blocks are shared.• JWLS estimation, channel estimation, and

combining strategies are different from SISO version.

16

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

17

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

18

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

19

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

20

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*

*

21

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

22

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

23

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.

24

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.