Experimental evaluations on carrier aggregation and multi-user MIMO associated with EVD-based CSI feedback for LTE-Advanced downlink

This paper presents laboratory experimental results on 4-by-2 multi-user (MU)-MIMO multiplexing with two mobile stations (MSs) in the LTE-Advanced downlink in combination with carrier aggregation (CA) using 5 component carriers (CCs). Extended channel state information (CSI) feedback functionality based on eigenvalue decomposition (EVD) is implemented into real-time experimental equipment based on the LTE-Advanced radio interface to support MU-MIMO operations applying minimum mean square error (MMSE)-based precoding. Laboratory experiments are conducted assuming a multi-path fading environment based on different antenna configurations. The experimental results show that 4-by-2 MU-MIMO with two data streams per MS achieves a peak throughput of greater than 950 Mbps, i.e., nearly 1 Gbps, in a correlated antenna configuration scenario when the maximum Doppler frequency is 10 Hz and the propagation channel model with the root mean squared delay spread is 0.3 μsec. The results also show that, high throughput performance such as greater than 750 Mbps for 4-by-2 MU-MIMO with two data streams per MS is achieved even in a non-correlated antenna configuration scenario although the environment is limited to low mobility and a small delay spread.