TR2006-102

Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks


    •  Mehta, N.B., Molisch, A.F., Greenstein, L.J., "Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks", IEEE Transactions on Wireless Communications, Vol. 5, No. 12, pp. 3394-3399, December 2006.
      BibTeX TR2006-102 PDF
      • @article{Mehta2006dec,
      • author = {Mehta, N.B. and Molisch, A.F. and Greenstein, L.J.},
      • title = {Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks},
      • journal = {IEEE Transactions on Wireless Communications},
      • year = 2006,
      • volume = 5,
      • number = 12,
      • pages = {3394--3399},
      • month = dec,
      • issn = {1536-1276},
      • url = {https://www.merl.com/publications/TR2006-102}
      • }
  • Research Area:

    Communications

Abstract:

The orthogonality factor (OF) quantifies the loss of orthogonality between the signals transmitted simultaneously on a wideband code division multiple access (WCDMA) downlink due to multipath dispersion. It is one of the fundamental parameters that determines the signal-to-interference-plus-noise ratio at the output of the Rake receiver and, consequently, it has a significant impact on downlink system capacity. The OF depends greatly on the delay profile of the multipath channel between the mobile and its serving base station; this profile varies considerably from one location in the cell to another. In this paper, we study how the statistical properties of the small-scale-fading-averaged OF vary over the entire macrocellular area. We use an ensemble of channel profiles at different locations in a cell generated from an implementation of the comprehensive COST259 channel model, which incorporates results from several experimental investigations. We show that the small-scale-fading-averaged OF is itself a random variable whose statistics depend on the mobile's distance from its serving base station. The large observed variance of the OF indicates that using a single value for all users in downlink capacity analyses and simulations, as has been the practice, may lead to erroneous conclusions. Finally, we propose a simple model that closely matches the statistics of the OF as a function of mobile-to-base distance, thus obviating the need to set up the complicated channel model every time OF values are to be generated.

 

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    •  NEWS    IEEE Transactions on Wireless Communications: 5 publications by Jinyun Zhang and others
      Date: December 1, 2006
      Where: IEEE Transactions on Wireless Communications
      MERL Contact: Jinyun Zhang
      Brief
      • The articles "Channel Statistics-Based RF Pre-Processing with Antenna Selection" by Sudarshan, P., Mehta, N.B., Molisch, A.F. and Zhang, J., "Macrocell-Wide Behavior of the Orthogonality Factor in WCDMA Downlinks" by Mehta, N.B., Molisch, A.F. and Greenstein, L.J., "Keyhole Effect in MIMO Wireless Channels: Measurements and Theory" by Almers, P., Tufvesson, F. and Molisch, A.F., "The COST 259 Directional Channel Model - Part 11: Macrocells" by Asplund, H., Glazunov, A.A., Molisch, A.F., Pedersen, K.I. and Steinbauer, M. and "The COST259 Directional Channel Model - Part I: Overview and Methodology" by Molisch, A.F., Asplund, H., Heddergott, R., Steinbauer, M. and Zwick, T. were published in IEEE Transactions on Wireless Communications.
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