Performance of multi-mode transmission with finite rate feedback in MIMO broadcast systems

This paper investigates the performance of adaptive transmission mode selection by user scheduling using zero-forcing beamforming (ZFBF) and finite-rate feedback (FRF). ZFBF is quite promising for multiple-input multiple-output (MIMO) broadcast systems, due to its simplicty. ZFBF can be utilized in compound with FRF, where the quantised channel direction information (CDI) of each user is fedback to the base station, and utilized to reduce the inter-user interference. User selection plays an important role in enhancing the performance of ZFBF systems. Recent progress on user scheduling in conjunction with multi-mode transmission schemes form the resulting investigations in this paper. This paper analyses an enhanced multi-mode transmission scheme along with proposed improvements on rate approximations at the user-side and shows promising results via monte-carlo simulations.