Skip to main content

Optimal and Suboptimal Finger Selection Algorithms for MMSE Rake Receivers in Impulse Radio Ultra-Wideband Systems

Abstract

The problem of choosing the optimal multipath components to be employed at a minimum mean square error (MMSE) selective Rake receiver is considered for an impulse radio ultra-wideband system. First, the optimal finger selection problem is formulated as an integer programming problem with a nonconvex objective function. Then, the objective function is approximated by a convex function and the integer programming problem is solved by means of constraint relaxation techniques. The proposed algorithms are suboptimal due to the approximate objective function and the constraint relaxation steps. However, they perform better than the conventional finger selection algorithm, which is suboptimal since it ignores the correlation between multipath components, and they can get quite close to the optimal scheme that cannot be implemented in practice due to its complexity. In addition to the convex relaxation techniques, a genetic-algorithm- (GA-) based approach is proposed, which does not need any approximations or integer relaxations. This iterative algorithm is based on the direct evaluation of the objective function, and can achieve near-optimal performance with a reasonable number of iterations. Simulation results are presented to compare the performance of the proposed finger selection algorithms with that of the conventional and the optimal schemes.

[123456789101112131415161718192021222324252627282930]

References

  1. 1.

    U. S. Federal Communications Commission, FCC 02-48: First Report and Order

  2. 2.

    Win MZ, Scholtz RA: Impulse radio: how it works. IEEE Communications Letters 1998,2(2):36-38. 10.1109/4234.660796

    Article  Google Scholar 

  3. 3.

    Win MZ, Scholtz RA: Ultra-wide bandwidth time-hopping spread-spectrum impulse radio for wireless multiple-access communications. IEEE Transactions on Communications 2000,48(4):679-691. 10.1109/26.843135

    Article  Google Scholar 

  4. 4.

    Ramirez Mireless F: On the performance of ultra-wideband signals in Gaussian noise and dense multipath. IEEE Transactions on Vehicular Technology 2001,50(1):244-249. 10.1109/25.917932

    Article  Google Scholar 

  5. 5.

    Scholtz RA: Multiple access with time-hopping impulse modulation. Proceedings of the IEEE Military Communications Conference (MILCOM '93), October 1993, Boston, Mass, USA 2: 447-450.

    Article  Google Scholar 

  6. 6.

    Cassioli D, Win MZ, Molisch AF: The ultra-wide bandwidth indoor channel: from statistical model to simulations. IEEE Journal on Selected Areas in Communications 2002,20(6):1247-1257. 10.1109/JSAC.2002.801228

    Article  Google Scholar 

  7. 7.

    Cassioli D, Win MZ, Vatalaro F, Molisch AF: Performance of low-complexity RAKE reception in a realistic UWB channel. Proceedings of the IEEE International Conference on Communications (ICC '02), April-May 2002, New York, NY, USA 2: 763-767.

    Article  Google Scholar 

  8. 8.

    Win MZ, Winters JH: Analysis of hybrid selection/maximal-ratio combining of diversity branches with unequal SNR in Rayleigh fading. Proceedings of the IEEE 49th Vehicular Technology Conference (VTC '99), May 1999, Houston, Tex, USA 1: 215-220.

    Google Scholar 

  9. 9.

    Kong N, Milstein LB: Combined average SNR of a generalized diversity selection combining scheme. Proceedings of the IEEE International Conference on Communications (ICC '98), June 1998, Atlanta, Ga, USA 3: 1556-1560.

    Google Scholar 

  10. 10.

    Yue L: Analysis of generalized selection combining techniques. Proceedings of the IEEE 51st Vehicular Technology Conference (VTC '00), May 2000, Tokyo, Japan 2: 1191-1195.

    Google Scholar 

  11. 11.

    Sui H, Masry E, Rao BD, Yoon YC: CDMA downlink chip-level MMSE equalization and finger placement. Proceedings of the 37th Asilomar Conference on Signals, Systems, and Computers, November 2003, Pacific Grove, Calif, USA 1: 1161-1165.

    Google Scholar 

  12. 12.

    Sui H, Masry E, Rao BD: RAKE finger placement for CDMA downlink equalization. Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing, March 2005, Philadelphia, Pa, USA 3: 905-908.

    Google Scholar 

  13. 13.

    Zhiwei L, Premkumar AB, Madhukumar AS: Matching pursuit-based tap selection technique for UWB channel equalization. IEEE Communications Letters 2005,9(9):835-837. 10.1109/LCOMM.2005.1506719

    Article  Google Scholar 

  14. 14.

    Fishler E, Poor HV: On the tradeoff between two types of processing gain. IEEE Transactions on Communications 2005,53(10):1744-1753. 10.1109/TCOMM.2005.855001

    MathSciNet  Article  Google Scholar 

  15. 15.

    Gezici S, Kobayashi H, Poor HV, Molisch AF: Performance evaluation of impulse radio UWB systems with pulse-based polarity randomization in asynchronous multiuser environments. Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC '04), March 2004, Atlanta, Ga, USA 2: 908-913.

    Google Scholar 

  16. 16.

    Nakache Y-P, Molisch AF: Spectral shape of UWB signals - influence of modulation format, multiple access scheme and pulse shape. Proceedings of the IEEE 57th Vehicular Technology Conference (VTC '03), April 2003, Jeju, Korea 4: 2510-2514.

    Google Scholar 

  17. 17.

    Lee D, Milstein LB: Comparison of multicarrier DS-CDMA broadcast systems in a multipath fading channel. IEEE Transactions on Communications 1999,47(12):1897-1904. 10.1109/26.809710

    Article  Google Scholar 

  18. 18.

    Xu W, Milstein LB: On the performance of multicarrier RAKE systems. IEEE Transactions on Communications 2001,49(10):1812-1823. 10.1109/26.957403

    MATH  Article  Google Scholar 

  19. 19.

    Gezici S, Kobayashi H, Poor HV, Molisch AF: Performance evaluation of impulse radio UWB systems with pulse-based polarity randomization. IEEE Transactions on Signal Processing 2005,53(7):2537-2549.

    MathSciNet  Article  Google Scholar 

  20. 20.

    Gezici S, Kobayashi H, Poor HV, Molisch AF: Optimal and suboptimal linear receivers for time-hopping impulse radio systems. Proceedings of the IEEE Conference on Ultra Wideband Systems and Technologies (UWBST '04), May 2004, Kyoto, Japan

    Google Scholar 

  21. 21.

    Molisch AF, Nakache Y-P, Orlik P, et al.: An efficient low-cost time-hopping impulse radio for high data rate transmission. Proceedings of the IEEE 6th International Symposium on Wireless Personal Multimedia Communications (WPMC '03), October 2003, Yokosuka, Kanagawa, Japan

    Google Scholar 

  22. 22.

    Verdú S: Multiuser Detection. Cambridge University Press, Cambridge, UK; 1998.

    Google Scholar 

  23. 23.

    Boyd S, Vandenberghe L: Convex Optimization. Cambridge University Press, Cambridge, UK; 2004.

    Google Scholar 

  24. 24.

    Nesterov Y, Nemirovskii A: Interior-Point Polynomial Methods in Convex Programming. SIAM, Philadelphia, Pa, USA; 1994.

    Google Scholar 

  25. 25.

    Haupt RL, Haupt SE: Practical Genetic Algorithms. John Wiley & Sons, New York, NY, USA; 1998.

    Google Scholar 

  26. 26.

    Goldberg DE: Genetic Algorithms in Search, Optimization, and Machine Learning. Addison-Wesley, Reading, Mass, USA; 1989.

    Google Scholar 

  27. 27.

    Mitchell M: An Introduction to Genetic Algorithms. MIT Press, Cambridge, Mass, USA; 1996.

    Google Scholar 

  28. 28.

    Juntti MJ, Schlösser T, Lilleberg JO: Genetic algorithms for multiuser detection in synchronous CDMA. Proceedings of the IEEE International Symposium on Information Theory, June-July 1997, Ulm, Germany 492.

    Google Scholar 

  29. 29.

    Ergün C, Hacioglu K: Multiuser detection using a genetic algorithm in CDMA communications systems. IEEE Transactions on Communications 2000,48(8):1374-1383. 10.1109/26.864174

    Article  Google Scholar 

  30. 30.

    Yen K, Hanzo L: Genetic-algorithm-assisted multiuser detection in asynchronous CDMA communications. IEEE Transactions on Vehicular Technology 2004,53(5):1413-1422. 10.1109/TVT.2004.832412

    Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Sinan Gezici.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Gezici, S., Chiang, M., Poor, H.V. et al. Optimal and Suboptimal Finger Selection Algorithms for MMSE Rake Receivers in Impulse Radio Ultra-Wideband Systems. J Wireless Com Network 2006, 084249 (2006). https://doi.org/10.1155/WCN/2006/84249

Download citation

Keywords

  • Minimum Mean Square Error
  • Relaxation Technique
  • Integer Programming Problem
  • Convex Relaxation
  • Rake Receiver