B3G and MIMO MCCDMA

1
B3G and MIMO MC-CDMA

• Speaker Pei-Yun Tsai
• Advisor Tzi-Dar Chiueh
• 2005/04/25

2
Outline

• Beyond 3G
• Evolution
• Main Features
• Possible Techniques
• MIMO MC-CDMA
• From SISO to MIMO
• Synchronization
• Channel estimation
• MIMO decoding
• Conclusion

3
Beyond 3G
4
Evolution of Mobile Systems
1
2010
5
Main 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 Radio Transmission

• Modulation 2 OFDM
• Robustness against frequency-selective fading
  channels in wide bandwidth
• Efficient spectrum utilization
• Flexibility in subcarrier allocation
• Adaptability in subcarrier modulation
• In 3GPP 4,
• Feasibility study of OFDM

7
Possible Techniques 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 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
Reliable Signal Cancellation
Informative Bit Decision
Combining
Informative Bit Decision
SPIC
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Possible Techniques 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 Radio Transmission

• MIMO comparison8

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Possible Techniques 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 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

13
MIMO MC-CDMA
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Consideration

• MIMO techniques
• STBC
• V-BLAST
• MIMO decoding
• Noise
• Multiple access interference (MAI)
• Inter antenna interference (IAI)

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MIMO MC-CDMA Receiver

• Synchronization blocks are shared.
• JWLS estimation, channel estimation, and
  combining strategies are different from SISO
  version.

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Hardware Requirement

• Derotator x 2
• FFT x 2

• Channel estimation x 4
• Equalizer (FEQ) x 4
• (More complicated)
• Despreading x 4
• SRAM for channel Response x 4
• EQ data delay buffers x 4
• Channel estimates delay buffers x4

• Additional data buffers (N)
• x 2

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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 0
Training symbol 1
Data symbol 0
Data symbol 1
Data symbol 2
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JWLS Estimation (2/2)

• Performance can be improved in the MIMO receiver
  due to increase of SINR.

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Channel Estimation

• Same performance as in the SISO cases at the same
  transmitted power.
• LS channel estimation
• Frequency-domain channel interpolation

MIMO
SISO
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Review of SUD in SISO MC-CDMA

• 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

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MIMO Processing - STBC (1/2)

• Consider SUD
• Apply TORC to reduce MAI, inter-antenna
  interference (IAI), and noise

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MIMO Processing - STBC (2/2)

• Apply MRC.
• Consider orthogonality restoring to reduce MAI.
• Avoid noise enhancement like TORC.

Gk
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Conclusion 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
Reference

• 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 division 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
  Magazine, vol. 1, pp. 40-52, Jan. 2005.
• 8 H. Yang,A road to future broadband
  wireless access MIMO-OFDM-based air
  interface,IEEE Communications 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-CDMA 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.