Multi-user MIMO in LTE: An exclusive low complex QRM-MLD detector with 2x2 antenna configuration

Multi-user multiple input and multiple output (MU-MIMO) is one of the key techniques in 3GPP Long-Term Evolution (LTE), which enhances the overall system capacity in the downlink. In order to reduce the effect of inter-user-interference in this system, it is necessary to utilize an efficient detection method at the user equipment (UE) that besides its feasibility at high data rate transmission systems such as LTE, must have a low computational complexity to be implemented into a small-sized UE. This paper proposes a new low complex detector for 2x2 MU-MIMO receiver in LTE downlink exclusively, which is based on the QRM-MLD algorithm. We will see that this presented method achieves an identical BER performance to that of the conventional QRM-MLD, however leads to at least 75% reduction in the complexity with respect to the conventional method, and furthermore, it avoids the unnecessary actions those exist in QRM-MLD while detecting each co-scheduled UE's signal in MU-MIMO LTE. Hence, it would be preferred from hardware implementation point of view.