Abstract

We study the problem of channel pairing and power allocation in a multi-channel, multi-hop relay network to enhance the end-to-end data rate. OFDM-based relays are used as an illustrative example, and the amplify-and-forward and decode-and-forward relaying strategies are considered. Given fixed power allocation to the OFDM subcarriers, we observe that a sorted-SNR subcarrier pairing strategy is data-rate optimal, where each relay pairs its incoming and outgoing subcarriers by their SNR order. For the joint optimization of subcarrier pairing and power allocation, we show that it is optimal to separately consider the two subproblems, for both individual and total power constraints. This separation principle significantly reduces the computational complexity in finding the jointly optimal solution. We further establish the equivalence between sorting SNRs and sorting channel gains in the jointly optimal solution, which allows simple implementation of optimal subcarrier pairing at the relays. Simulation results are presented to demonstrate the performance gain of the jointly optimal solution over some suboptimal alternatives.

Keywords

Orthogonal Frequency Division Multiplex Power Allocation Relay Node Channel Gain Orthogonal Frequency Division Multiplex System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Hottinen, A., Heikkinen, T.: Subchannel assignment in OFDM relay nodes. In: Annual Conf. on Information Sciences and Systems, Princeton, NJ (March 2006)Google Scholar
  2. 2.
    Herdin, M.: A chunk based OFDM amplify-and-forward relaying scheme for 4g mobile radio systems. In: Proc. IEEE Int. Conf. Communications (ICC), vol. 10 (June 2006)Google Scholar
  3. 3.
    Li, Y., Wang, W., Kong, J., Hong, W., Zhang, X., Peng, M.: Power allocation and subcarrier pairing in OFDM-based relaying networks. In: Proc. IEEE Int. Conf. Communications (ICC) (May 2008)Google Scholar
  4. 4.
    Shen, Z., Wang, X., Zhang, H.: Power allocation and subcarrier pairing for OFDM-based AF cooperative diversity systems. In: Proc. IEEE Vehicular Technology Conf, VTC (April 2009)Google Scholar
  5. 5.
    Vandendorpe, L., Duran, R., Louveaux, J., Zaidi, A.: Power allocation for OFDM transmission with DF relaying. In: Proc. IEEE Int. Conf. Communications, ICC (2008)Google Scholar
  6. 6.
    Hammerstrom, I., Wittneben, A.: Power allocation schemes for amplify-and-forward MIMO-OFDM relay links. IEEE Trans. Wireless Commun. 6(8), 2798–2802 (2007)CrossRefGoogle Scholar
  7. 7.
    Hajiaghayi, M., Dong, M., Liang, B.: Using limited feedback in power allocation design for a two-hop relay OFDM system. In: Proc. IEEE Int. Conf. Communications (ICC), vol. 2 (June 2009)Google Scholar
  8. 8.
    Wang, W., Yan, S., Yang, S.: Optimally joint subcarrier matching and power allocation in OFDM multihop system. EURASIP J. Appl. Signal Process, USA (March 2008)Google Scholar
  9. 9.
    Wang, W., Wu, R.: Capacity maximization for OFDM two-hop relay system with separate power constraints. IEEE Trans. Veh. Technol. 58(9), 4943–4954 (2009)CrossRefGoogle Scholar
  10. 10.
    Zhang, X., Gong, Y.: Adaptive power allocation for multi-hop OFDM relaying systems. In: Int. Conf. on Infor., Commun., Signal Processing, ICICS (2007)Google Scholar
  11. 11.
    Zhang, X., Jiao, W., Tao, M.: End-to-end resource allocation in OFDM based linear multi-hop networks. In: Proc. IEEE INFOCOM (2008)Google Scholar
  12. 12.
    Cover, T., El Gamal, A.: Capacity theorems for the relay channel. IEEE Trans. Inform. Theory 25(5), 572–584 (1979)MathSciNetCrossRefMATHGoogle Scholar
  13. 13.
    Laneman, J., Wornell, G., Tse, D.: An efficient protocol for realizing cooperative diversity in wireless networks. In: Proc. IEEE Int. Symp. on Infor. Theory, ISIT (2001)Google Scholar
  14. 14.
    Hasna, M., Alouini, M.-S.: Outage probability of multihop transmission over Nakagami fading channels. IEEE Commun. Lett. 7(5), 216–218 (2003)CrossRefGoogle Scholar
  15. 15.
    Tse, D., Viswanath, P.: Fundamentals of wireless communication. Cambridge University Press, New York (2005)CrossRefMATHGoogle Scholar

Copyright information

© ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering 2012

Authors and Affiliations

  • Mahdi Hajiaghayi
    • 1
  • Min Dong
    • 2
  • Ben Liang
    • 1
  1. 1.Dept. of Electrical and Computer EngineeringUniversity of TorontoCanada
  2. 2.Faculty of Eng. and App. Sci.University of Ontario Institute of TechnologyCanada

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