on the capacity of cooperative communication in correlated fading channels

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on the capacity of cooperative communication in
correlated fading channels

• presenter guchun zhang
• co-authors dr. Xiaohong Peng
• dr. Xuanye Gu (BT)

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contents

• cooperative system description
• correlation consideration
• system capacity formulation in correlation
  scenario
• modelling of spatial correlated fading channels
• simulation results
• conclusions

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a 3-node cooperative system
phase i
phase ii

• one source node, one relay node,
• and one destination node
• concerned mac-layer protocols 1
• fixed amplify-forward and selection
  decode-forward

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correlation scenario

• correlation occurs in phase i only
• capacity of correlated system, modified from 1
• source-destination channel dominates in both
  protocols

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correlated fading channels i

• correlation between source-destination channel
  and source-relay channel
• asymmetric system in terms of fading coefficients
• channel modelling, based on 2
• H channel matrix in correlation scenario
• HIND independent and nonidentically distributed
  channel matrix

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correlated fading channels ii

• the columns of UR and UT correspond to the
  eigenvectors of EHH and EHH, respectively.
• UT111 here.
• the variances of the entries in HIND are the
  eigenvalues of the covariance matrix, Q, of H,
  which can be modelled as, in this case,
• s standard deviation ß amplitude of
  correlation coefficient ? angle of correlation
  coefficient

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correlated fading channels iii

• through the standard process of calculating
  eigenvalues, the eigenvalues of Q are found as
• the relative eigenvectors are

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correlated fading channels iv

• present var(chn_cor) with respect to ß and
  var(chn_uncor) as
• better channel with no correlation effect remains
  better in correlation scenario
• better channel degraded, worse channel improved
  by correlation with same amount, ?
• higher ß, higher ?

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simulations

• var(chn_cor) used in simulations
• results presented using outage capacity
• simulation configurations

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simulation results i

• lts-d bettergt - capacity degradation

fixed amplify-forward
selection decode-forward
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simulation results ii

• lts-r bettergt - capacity improvement

fixed amplify-forward
selection decode-forward
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conclusions

• modelling of an asymmetric cooperative system
• better channel with no correlation effect remains
  better in correlation scenario
• better channel degraded, worse channel improved
  by correlation with same amount
• channel capacity can be improved by correlation
  if the quality of the source-destination channel
  becomes better due to correlation

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major references

• J. N. Laneman, D. N. C. Tse, and G. W. Wornell,
  Cooperative diversity in wireless networks
  efficient protocols and outage behavior, IEEE
  Trans. Inform. Theory, vol. 50, pp. 3062-3080,
  Dec. 2004.
• A. M. Tulino, A. Lozano, and S. Verdú, Impact of
  antenna correlation on the capacity of
  multiantenna channels, IEEE Trans. Inform.
  Theory, vol. 51, pp. 2491-2509, July 2005.

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question time
thank You