Multiuser Limited Feedback
For multiuser systems, limited feedback methods must be jointly designed with scheduling and multiple access methods to minimize the negative effects due to CSI inaccuracy and the retain feedback efficiency. Presently, we consider a space division multiple access (SDMA) downlink, which supports simultaneous users via their spatial separation and hence requires no additional bandwidth. Our initial results are summarized as follows. First, for SDMA with limited feedback, we have proposed a joint beamforming and scheduling algorithm, which takes into account CSI quantization errors in scheduling. The proposed algorithm is shown to achieve the multiuser diversity gain, thereby ensuring that the sum capacity increases with the number of users double logarithmically. Second, we proposed a threshold-based distributed feedback method that guarantees the average sum feedback rate from all users is upper-bounded by a constant. This solution is particularly attracted for implementing modern communication system such as 3GPP-LTE, where all users share a feedback control channel with a small bandwidth.
Related Publications and Preprints:
[1] K. Huang, R. W. Heath, Jr., and J. G. Andrews, ``Space Division Multiple Access with a Sum Feedback Rate Constraint,'' submitted to IEEE Trans. on Signal Processing, August 2006. Also available on ArXiv
[2] K. Huang, R. W. Heath, Jr., and J. G. Andrews, ``Joint Beamforming and Scheduling for SDMA Systems with Limited Feedback,'' submitted to IEEE Trans. on Communications, June 2006. Also available on ArXiv
[3] K. Huang, R. W. Heath, Jr., and J. G. Andrews, “Space division multiple access with a sum feedback rate constraint,” submitted to IEEE Int. Conf. Acoust., Speech and Sig. Proc. 2007, Sept. 2006.
[4] K. Huang, J. G. Andrews, and R. W. Heath, Jr., “Orthogonal beamforming for SDMA downlink with limited feedback,” submitted to IEEE Int. Conf. Acoust., Speech and Sig. Proc. 2007, Sept. 2006.
