On closed loop transmit diversity for HSDPA - using an orthogonality matrix for system level evaluations

The paper studies closed loop (CL) transmit diversity in combination with high speed downlink packet access (HSDPA). A potential problem with this combination is the reduced interference predictability which affects scheduling and link adaptation. To study this, the orthogonality factor (OF), which is used to model the intra-cell interference for single antenna transmission and reception, is augmented by an orthogonality matrix (OM), which is used for dynamic system level evaluations. The results indicate that the reduced predictability may decrease system performance in terms of cell throughput by approximately one third for a system employing multiuser diversity in a dispersive environment. However, by scheduling multiple users in a certain proposed way, interference fluctuations may be reduced, and results show that the performance may be improved. A simple spatial channel model is used so that the impact of fading correlation is considered as well.

[1]  Larry J. Greenstein,et al.  Analysis and results for the orthogonality factor in WCDMA downlinks , 2002, Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367).

[2]  R. Michael Buehrer,et al.  The impact of multiuser diversity on space-time block coding , 2003, IEEE Communications Letters.

[3]  Preben Mogensen,et al.  Network Performance of Transmit and Receive Diversity in HSDPA under Different Packet Scheduling Strategies , 2003 .

[4]  P.E. Mogensen,et al.  Network performance of transmit and receive antenna diversity in HSDPA under different packet scheduling strategies , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[5]  P.E. Mogensen,et al.  Interaction of transmit diversity and proportional fair scheduling , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[6]  Antti Toskala,et al.  WCDMA for UMTS: Radio Access for Third Generation Mobile Communications , 2000 .

[7]  Stefan Parkvall,et al.  The high speed packet data evolution of WCDMA , 2001, 12th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications. PIMRC 2001. Proceedings (Cat. No.01TH8598).

[8]  Stefan Parkvall,et al.  Impacts of higher order modulation on HS-DSCH system performance , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[9]  David Tse,et al.  Opportunistic beamforming using dumb antennas , 2002, IEEE Trans. Inf. Theory.

[10]  Antti Toskala,et al.  Wcdma for Umts , 2002 .

[11]  Klaus I. Pedersen,et al.  Effects of Other-Sector Interference Variation on Detection, Link Adaptation and Scheduling in HSDPA , 2004 .