An Algorithm for 2-User Downlink SDMA Beamforming with Limited Feedback for MIMO-OFDM Systems

Recent information theoretic results on MIMO broadcast channels have promoted research attention on devising practical transmit-receive strategies that achieve a reasonable fraction of the broadcast capacity. This paper proposes an algorithm for SDMA weight construction for two users. The weights are chosen to represent a subspace that lies between the dominant signal subspace of one user and the nullspace of the other. This proposal is unique due to its practical considerations - a broadband MIMO broadcast channel employing OFDM, imperfect CSI at the transmitter in the form of codebook based limited feedback, coded BER as a performance metric, and the ability to choose the users for SDMA arbitrarily. Simulation results in an IEEE 802.16e-style setup show that a coded BER within 1-2 dB of the case of perfect CSI can be achieved with a feedback of less than 1 bit per subcarrier. Additionally, maximum ratio combining receivers suffice and they may be oblivious to the multi-user nature of the SDMA transmission.

[1]  Andrea J. Goldsmith,et al.  Duality, achievable rates, and sum-rate capacity of Gaussian MIMO broadcast channels , 2003, IEEE Trans. Inf. Theory.

[2]  Babak Hassibi,et al.  On the capacity of MIMO broadcast channels with partial side information , 2005, IEEE Transactions on Information Theory.

[3]  Shlomo Shamai,et al.  The capacity region of the Gaussian MIMO broadcast channel , 2004, International Symposium onInformation Theory, 2004. ISIT 2004. Proceedings..

[4]  Nihar Jindal,et al.  MIMO broadcast channels with finite rate feedback , 2006, GLOBECOM '05. IEEE Global Telecommunications Conference, 2005..

[5]  Michael D. Zoltowski,et al.  Multiple Antenna Broadcast Channels With Limited Feedback , 2006, 2006 IEEE International Conference on Acoustics Speech and Signal Processing Proceedings.

[6]  R.C. Johnson,et al.  Introduction to adaptive arrays , 1982, Proceedings of the IEEE.

[7]  Khaled Ben Letaief,et al.  A joint-channel diagonalization for multiuser MIMO antenna systems , 2003, IEEE Trans. Wirel. Commun..

[8]  R.W. Heath,et al.  Algorithms for Quantized Precoded MIMO-OFDM Systems , 2005, Conference Record of the Thirty-Ninth Asilomar Conference onSignals, Systems and Computers, 2005..

[9]  Shlomo Shamai,et al.  On the achievable throughput of a multiantenna Gaussian broadcast channel , 2003, IEEE Transactions on Information Theory.

[10]  Michael D. Zoltowski,et al.  Multiple Antenna Broadcast Channels With Shape Feedback and Limited Feedback , 2007, IEEE Transactions on Signal Processing.

[11]  Aylin Yener,et al.  Transceiver optimization for multiuser MIMO systems , 2004, IEEE Transactions on Signal Processing.

[12]  G. Wornell,et al.  MIMO Broadcast Scheduling with Limited Channel State Information , 2005 .

[13]  Babak Hassibi,et al.  On the capacity of MIMO broadcast channels with partial channel state information , 2003 .

[14]  Gregory W. Wornell,et al.  MIMO Broadcast Scheduling with Quantized Channel State Information , 2006, 2006 IEEE International Symposium on Information Theory.

[15]  Robert W. Heath,et al.  Grassmannian beamforming for multiple-input multiple-output wireless systems , 2003, IEEE International Conference on Communications, 2003. ICC '03..

[16]  Holger Boche,et al.  Solution of the multiuser downlink beamforming problem with individual SINR constraints , 2004, IEEE Transactions on Vehicular Technology.