Effects of PA Nonlinearity and Dynamic Range in Spatially Multiplexed Precoded MIMO Systems

In this paper, we study the effects of nonlinear distortion caused by RF power amplifiers (PAs) to the performance of singular value decomposition-based linear precoding and spatial multiplexing (SM). The goal is to define the requirements of the individual PAs in SM multiple-input multiple-output (MIMO) systems to enable rank N transmission. The distortion of the independent data streams are shown to be coupled in PA output. Polynomial PA model and antenna array factor are used to model the antenna patterns of the distortion components and it is shown that part of the distortion can be canceled by beamforming them to unharmful directions. The effects in 16x4 MIMO system with 64-QAM modulated signals are demonstrated by simulating error vector magnitude of individual data streams in System Vue simulation environment. It is concluded that the signal dynamics between the streams should be taken into account when designing PAs for future telecommunication systems.