Signal ProcessingAn iterative space subchannel allocation algorithm for multiuser MIMO/OFDM systems

In multiuser multiple-input multiple-output/orthogonal frequency-division multiplexing (MIMO/OFDM) systems, the EigenValue Decomposition (EVD) method was proposed to construct a number of parallel spatial channels. The beamforming technique which only exploits the spatial subchannel related to the largest eigenvalue is usually adopted in many papers to deal with adaptive resource allocation. Although these previous studies could maximise the received signal-to-noise ratio (SNR), they could not get the maximum system throughput. In this paper, all the spatial subchannel are investigated. With the goal of maximising the overall system throughput, we derive a simple effective criterion of subcarrier allocation and introduce an adaptive resource allocation algorithm. The proposed algorithm could get higher system throughput especially at high SNR, that is the spectral efficiency is improved about 3 bit/s/Hz at 14 dB. At the same time, in order to decrease the computational complexity, a time-frequency blockwise loading design is suggested. In practical channel with partial channel state information (CSI), a modified algorithm based on mean feedback model is proposed. The simulation results show that under imperfect CSI, the modified algorithm could achieve optimum system throughput while guaranteeing prescribed error performance. On the other hand, in comparison to perfect CSI, the system throughput decreases. Copyright © 2008 John Wiley & Sons, Ltd.

[1]  Edgar Bolinth,et al.  A blockwise loading algorithm for the adaptive modulation technique in OFDM systems , 2001, IEEE 54th Vehicular Technology Conference. VTC Fall 2001. Proceedings (Cat. No.01CH37211).

[2]  Khaled Ben Letaief,et al.  An efficient resource-allocation scheme for spatial multiuser access in MIMO/OFDM systems , 2005, IEEE Transactions on Communications.

[3]  Mohammad Ali Khalighi,et al.  Water filling capacity of Rayleigh MIMO channels , 2001, 12th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications. PIMRC 2001. Proceedings (Cat. No.01TH8598).

[4]  Zhigang Cao,et al.  Spatial multiuser access with MIMO smart antennas for OFDM systems , 2001, IEEE 54th Vehicular Technology Conference. VTC Fall 2001. Proceedings (Cat. No.01CH37211).

[5]  Andrea J. Goldsmith,et al.  Variable-rate variable-power MQAM for fading channels , 1997, IEEE Trans. Commun..

[6]  Upamanyu Madhow,et al.  Space-Time transmit precoding with imperfect feedback , 2001, IEEE Trans. Inf. Theory.

[7]  Zhigang Cao,et al.  Dynamic resource allocation with adaptive beamforming for MIMO/OFDM systems under perfect and imperfect CSI , 2004, 2004 IEEE Wireless Communications and Networking Conference (IEEE Cat. No.04TH8733).

[8]  Björn E. Ottersten,et al.  Power allocation and bit loading for spatial multiplexing in MIMO systems , 2003, 2003 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2003. Proceedings. (ICASSP '03)..

[9]  Yanhui Lu,et al.  Dynamic Spatial Subcarrier and Power Allocation for Multiuser MIMO-OFDM System , 2007, 2007 International Conference on Wireless Communications, Networking and Mobile Computing.

[10]  John M. Cioffi,et al.  Spatio-temporal coding for wireless communication , 1998, IEEE Trans. Commun..

[11]  M. J. Gans,et al.  On Limits of Wireless Communications in a Fading Environment when Using Multiple Antennas , 1998, Wirel. Pers. Commun..

[12]  Khaled Ben Letaief,et al.  Adaptive antennas at the mobile and base stations in an OFDM/TDMA system , 2001, IEEE Trans. Commun..

[13]  Ying-Chang Liang,et al.  Transmit Optimization for MIMO-OFDM With Delay-Constrained and No-Delay-Constrained Traffic , 2006, IEEE Transactions on Signal Processing.

[14]  J.A.C. Bingham,et al.  Multicarrier modulation for data transmission: an idea whose time has come , 1990, IEEE Communications Magazine.

[15]  Georgios B. Giannakis,et al.  Optimal transmitter eigen-beamforming and space time block coding based on channel mean , 2002, 2002 IEEE International Conference on Acoustics, Speech, and Signal Processing.