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Relay Techniques for MIMO Wireless Networks with Multiple Source and Destination Pairs

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A multiple-input multiple-output (MIMO) relay network comprises source, relay, and destination nodes, each of which is equipped with multiple antennas. In a previous work, we proposed a MIMO relay scheme for a relay network with a single source and destination pair in which each of the multiple relay nodes performs QR decompositions of the backward and forward channel matrices in conjunction with phase control (QR-P-QR). In this paper, we extend this scheme to a MIMO relay network employing multiple source and destination pairs. Towards this goal, we use a group nulling approach to decompose a multiple S-D MIMO relay channel into parallel independent S-D MIMO relay channels, and then apply the QR-P-QR scheme to each of the decomposed MIMO relay links. We analytically show the logarithmic capacity scaling of the proposed relay scheme. Numerical examples confirm that the proposed relay scheme offers higher capacity than existing relay schemes.



  1. 1.

    Gastpar M, Vetterli M: On the capacity of wireless networks: the relay case. Proceedings of the 21st Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM '02), June 2002, New York, NY, USA 3: 1577–1586.

  2. 2.

    Telatar IE: Capacity of multi-antenna Gaussian channels. European Transactions on Telecommunications 1999,10(6):585–595. 10.1002/ett.4460100604

  3. 3.

    Foschini GJ, Gans MJ: On limits of wireless communications in a fading environment when using multiple antennas. Wireless Personal Communications 1998,6(3):311–335. 10.1023/A:1008889222784

  4. 4.

    Raleigh GG, Cioffi JM: Spatio-temporal coding for wireless communication. IEEE Transactions on Communications 1998,46(3):357–366. 10.1109/26.662641

  5. 5.

    Winters JH: On the capacity of radio communication systems with diversity in a Rayleigh fading environment. IEEE Journal on Selected Areas in Communications 1987,5(5):871–878. 10.1109/JSAC.1987.1146600

  6. 6.

    Goldsmith A, Jafar SA, Jindal N, Vishwanath S: Capacity limits of MIMO channels. IEEE Journal on Selected Areas in Communications 2003,21(5):684–702. 10.1109/JSAC.2003.810294

  7. 7.

    Caire G, Shamai S: On the achievable throughput of a multiantenna Gaussian broadcast channel. IEEE Transactions on Information Theory 2003,49(7):1691–1706. 10.1109/TIT.2003.813523

  8. 8.

    Vishwanath S, Jindal N, Goldsmith A: Duality, achievable rates, and sum-rate capacity of Gaussian MIMO broadcast channels. IEEE Transactions on Information Theory 2003,49(10):2658–2668. 10.1109/TIT.2003.817421

  9. 9.

    Yu W, Cioffi JM: Sum capacity of Gaussian vector broadcast channels. IEEE Transactions on Information Theory 2004,50(9):1875–1892. 10.1109/TIT.2004.833336

  10. 10.

    Bölcskei H, Nabar RU, Oyman Ö, Paulraj AJ: Capacity scaling laws in MIMO relay networks. IEEE Transactions on Wireless Communications 2006,5(6):1433–1444.

  11. 11.

    Nabar RU, Oyman Ö, Bölcskei H, Paulraj AJ: Capacity scaling laws in MIMO wireless networks. Proceedings of Allerton Conference on Communication, Control, and Computing, October 2003, Monticello, Ill, USA 378–389.

  12. 12.

    Shi H, Abe T, Asai T, Yoshino H: A relaying scheme using QR decomposition with phase control for MIMO wireless networks. Proceedings of IEEE International Conference on Communications (ICC '05), May 2005, Seoul, Korea 4: 2705–2711.

  13. 13.

    Cover TM, Thomas JA: Elements of Information Theory. John Wiley & Sons, New York, NY, USA; 1991.

  14. 14.

    Choi L-U, Murch RD: A transmit preprocessing technique for multiuser MIMO systems using a decomposition approach. IEEE Transactions on Wireless Communications 2004,3(1):20–24. 10.1109/TWC.2003.821148

  15. 15.

    Bölcskei H, Nabar RU: Realizing MIMO gains without user cooperation in large single-antenna wireless networks. Proceedings of IEEE International Symposium on Information Theory, June-July 2004, Chicago, Ill, USA 18.

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Correspondence to Tetsushi Abe.

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  • Destination Node
  • Relay Node
  • Relay Network
  • Destination Pair
  • Logarithmic Capacity