Efficient combination of multi-user MIMO THP and user selection based on spatial orthogonality

This paper proposes an efficient method for combing multi-user MIMO (MU-MIMO) employing Tomlinson Harashima precoding (THP) with semiorthogonal user selection (SUS). Although the ordering of MU-MIMO THP and SUS create space diversity benefit and multi-user diversity benefit, respectively, a significant computational effort is required, which is expected to be relaxed while retaining the system level performance. The proposed method is inspired by the fact that the ordering calculations of MU-MIMO THP and SUS are commonly based on the spatial orthogonality. If that is the case, the result of the ordering of SUS is fully reused for the ordering of MU-MIMO THP, which can eliminate the calculation process of the ordering of MU-MIMO THP. The effectiveness of the proposed method is demonstrated in comparison with the traditional method with the ordering of MU-MIMO THP by means of computer simulations.