A new transmission strategy that consists of a spatial scheduling algorithm and two precoding algorithms is developed for multicarrier multiuser (MU) multiple-input-multiple-output (MIMO) systems. The scheduling algorithm, which is called efficient multicarrier ProSched (EMC-ProSched), adopts a novel and effective scheduling metric for each user and can efficiently search for a suitable group of users to be served at the same time on the same frequency. Two precoding techniques are then designed to handle different antenna configurations. For the case where the number of transmit antennas at the base station (BS) is not smaller than the total number of receive antennas at the user terminals (UTs), the linear-precoding-based geometric mean decomposition (LP-GMD) algorithm is proposed. It suppresses the MU interference (MUI) and enables an effective implementation of the same modulation and coding scheme (MCS) on all spatial streams of each user. Consequently, smaller signaling overhead is required compared with the case where a different MCS is applied on each spatial stream. When the total number of receive antennas at the UTs exceeds the number of transmit antennas at the BS, we propose the low-complexity coordinated beamforming (LoCCoBF) algorithm to accomplish the goal of the MUI mitigation and to achieve a high capacity. A system-level simulator with a link-to-system interface is further developed under the framework of the IEEE 802.11ac standard to evaluate the performance of the proposed transmission strategy. The simulation results indicate that a promising performance can be achieved by employing the proposed transmission strategy.

In this work, a novel linear precoding algorithm, called linear precoding-based geometric mean decomposition (LP-GMD), is proposed for the downlink of multi-user (MU) multiple-input multiple-output (MIMO) systems. The proposed scheme suppresses the multi-user interference (MUI) at the BS. Then it uses the GMD to decompose the equivalent single-user MIMO channel into multiple parallel sub-channels that have the same effective signal to interference plus noise ratio (SINR), which allows the use of the same modulation and coding scheme (MCS) for different spatial streams of each user. A system-level simulator is then set up based on the IEEE 802.11ac standard. The simulation results indicate that the proposed algorithm provides a significant gain as compared to conventional linear precoding algorithms such as block diagonalization (BD) and regularized block diagonalization (RBD).

A transmission strategy that consists of a spatial scheduling algorithm and a precoding algorithm is developed for multi-carrier (MC) multi-user (MU) multiple-input multiple-output (MIMO) systems. The scheduling algorithm, called efficient multi-carrier ProSched (EMC-ProSched), adopts a novel scheduling metric that is able to efficiently perform the user selection for a multi-carrier system. The precoding algorithm, called low complexity coordinated beamforming (LoCCoBF), is developed to achieve a high capacity in the scenarios where the number of the transmit antennas at the base station is smaller or equal to the total number of receive antennas at the user terminals with a low complexity. A system-level simulator is then developed based on the IEEE 802.11ac standard and the simulation results indicate that a promising performance can be achieved by employing the proposed transmission strategy.