Radio Resource and Interference Management in Uplink Multi-Cell MU-MIMO Systems with ZF Post-Processing

This paper presents our initial investigations of noise enhancement control when decoding uplink transmissions in multi-cell multiuser multiple- input multiple-output (MU-MIMO) systems with zero- forcing (ZF) post-processing. This problem has been partially addressed within simplified cellular system topologies and with single antenna terminals. However, applying existing solutions directly to a multi cell system is not viable due to the noise enhancement that would heavily affect the inter-cell interference (ICI). Therefore, this paper proposes a cross-layer resource allocation to improve the performance by utilizing a low complexity scheduling (user and antenna selection) and a power allocation method. The proposed scheduling algorithm extends our previous work to a multi cell system where the base and the mobile stations are equipped with multiple antennas. When allocating the power levels to different users in order to manage the multiple access interference (MAI) in MU-MIMO environment, we utilize Newton´s method for resource optimization due to its efficiency in finding the combination of spatial streams and power levels to improve the average bit error rates (BERs) and their statistics for different users. This improvement in BERs is documented in terms of median and average BER performance in the system under study with and without centralized ICI cancelation.