Adaptive radiofrequency resource management for MIMO MCCDMA on antenna selection

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Adaptive radio-frequency resource management for
MIMO MC-CDMA on antenna selection

• Jingxu Han and Mqhele E Dlodlo
• Department of Electrical Engineering
• University of Cape Town

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What is MIMO?

• MIMO (Multiple Input Multiple Output) is a new
  wireless technology conceived in the mid 90s
• Greatly improves the reliability, range and
  robustness of existing wireless communication
  systems
• Can provide high data rate (channel capacity)
  high QoS (low bit error rate)
• Selected for many standards, such as W-CDMA

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Introduction of MC CDMA

• Multi-carriers CDMA (MC CDMA) is a multiple
  access technology used in wireless communication
  systems based on OFDM
• a strong candidate as an access technique for
  downlink of broadband cellular systems
• Obtains benefits from both MC and CDMA
  techniques high spectral efficiency, robustness
  in frequency selective channels

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Combination of MIMO MC-CDMA systems

• A promising technology for 4G wireless
  communication since
• 1 high date rate
• 2 high Qos
• 3 multiple users communication
• 4 high spectral efficiency

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Why antenna selection?

• An inherent drawback for multiple antenna system
  is the increased hardware complexity due to the
  requirement for radio-frequency chain.
• Corresponding to power amplifiers, mixers analog
  to digital converter ect.
• An ideal approach to reduce the complexity of a
  multiple antennas system while maintaining the
  advantages

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Ideas behind antenna selection

• Choose a subset of best performance antennas
  either in transmission and/ or reception to feed
  to the RF chain for signal processing
• Existing algorithms
• 1) maximum signal to noise ratio
• 2) maximum channel mean
• 3) minimum instantaneous probability of error

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Proposing algorithm

• An improved low complexity algorithm proposed
  based on maximum ratio method
• the method is simplified to choose the best
  performance antenna from all the possible
  antennas, then choose the best performance
  antenna from the rest possible antennas instead
  of calculate Frobenius norm for all the possible
  antennas

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Complexity comparison

• For instance selecting 2 antennas out of 10
  antennas
• Old algorithm calculation complexity is 45
• Correspondingly the novel one is 19

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Adaptive RF management

• Aim to flexibly manage RF resource for MIMO
  MC-CDMA systems based on antenna selection
• 1) Set target bit error rate
• 2) find out minimum number of antennas to feed RF
  need
• 3) adaptive increasing the number of antennas on
  increment of users or interferences

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Simulation results
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Conclusion

• A novel transmission adaptive technique for MIMO
  MC-CDMA system as an aim to flexibly manage radio
  frequency resource based on antenna selection is
  presented
• The simulation results, depending on both numbers
  of users and signal to noise ratio (SNR) value,
  show significant gains compared to fixed systems
  for a predefined target bit error rate (BER)

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Future work

• Performance investigation for the real MIMO
  channels are needed
• Effective feedback path is necessary to insure
  the system, and performance over fast fading
  channel is also an interesting topic.

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• Thanks
• Questions?