In the ever-evolving landscape of wireless communication, multi-user multiple-input multiple-output (MU-MIMO) systems have emerged as a promising technology to enhance data rates and reliability. However, the non-linear behavior of power amplifiers (PAs) in these systems can cause a significant degradation in the performance of linear precoding schemes, such as the zero-forcing (ZF) precoder, which are designed to manage interference between user equipments (UEs).
To mitigate this issue, digital pre-distortion (DPD) modules are often employed to linearize the PAs. Nevertheless, using perfect DPD modules can be quite costly and may lead to substantial power consumption. This has led researchers Juan Vidal Alegría, Ashkan Sheikhi, and Ove Edfors to explore an alternative approach: characterizing non-linearity-aware ZF (NLA-ZF) precoding schemes.
NLA-ZF precoding schemes are essentially linear precoders that achieve perfect interference cancellation in the presence of PA non-linearity by leveraging knowledge of this non-linear response. The researchers have provided initial iterative solutions that enable achieving NLA-ZF (up to an adjustable tolerance) in a two-UE downlink MU-MIMO scenario. In this scenario, the base station (BS) has an even number of antennas, and each antenna is connected to a PA exhibiting third-order memory-less non-linear behavior.
The proposed approach by Alegría, Sheikhi, and Edfors holds significant potential for performance gains, particularly in scenarios with substantial residual interference. This research not only sheds light on the intricate interplay between PA non-linearities and precoding schemes but also paves the way for more efficient and cost-effective solutions in MU-MIMO systems. As the demand for high-speed, reliable wireless communication continues to grow, such advancements are crucial in shaping the future of the telecommunication industry.
