Maximum Eigenmode Beamforming with Unbalanced MIMO Configurations

For a multiple-input multiple-output (MIMO) system, a balanced configuration with equal number of antennas at the transmitter and receiver sides is an optimal solution in theory. However, a bulky mobile unit with multiple antennas is always something the researchers want to avoid. On the other hand, a base station usually has more space for more antennas. Thus an unbalanced configuration with unequal numbers of antennas at the transmitter and receiver sides is preferable in practice.In this project, the researchers will investigate unbalanced configurations together with a low-cost maximum eigenmode beamforming (MEB) strategy that can deliver performance close to optimal balanced configurations. Multi-user concurrent transmission and multi-user detection are key techniques to achieve this goal. They will develop analysis techniques to quantify the difference between the optimal and sub-optimal options. They will study the impacts of non-ideal factors such as the correlation among the antennas in a mobile unit and the inaccuracy in channel state information.The researchers will investigate efficient detection algorithms the MEB strategy. This involves a joint strategy to handle multiple-access interference, inter-symbol interference and cross-antenna interference. They will explore low complexity realization techniques that are suitable for practical use.In summary, the researchers plan to develop a framework that can deliver near optimal multi-user MIMO performance while avoid using too many antennas at each mobile unit. This can remove a major obstacle in the application of the MIMO principle.