Prof. Dr.-Ing. Werner Henkel, Khaled Shawky Hassan
In this work we look into the problem of inter-user interference in multiuser MIMO systems. We disscuss two different SDMA MIMO schemes. The first scheme, the orthogonal SDMA, completely eliminates the inter-user interferance. It block-diagonalizes the MIMO channel resulting in zero MUI, leaving each user to deal with its own interference. This scheme, however, puts a dimension limitation on the MIMO system such that the total number of transmit antennas are equal to or great than the total number of receive antennas on all users. The other scheme, the MMSE SDMA, iteratively minimizes the mean squared error which contains both, the inter-user interference and inter-symbol interference. We study an algorithm which divides the joint transmit-receive MMSE optimization problem into two sub-problems. It computes the optimum transmit filters with a constraint of total transmit power for all users, and then computes the receive filters from these optimized transmit filters.
[Report] Comparison of MMSE SDMA with Orthogonal SDMA Approach