Impact of Channel Prediction on the Performance of MIMO E-SDM Systems in Actual Dynamic Channels

By transmitting orthogonal eigenbeams and controlling transmit data resource allocation, the Multiple-Input Multiple-Output (MIMO) system using an Eigenbeam-Space Division Multiplexing (ESDM) technique, namely MIMO E-SDM system, performs very well and is considered as one of the promising candidates for future high-rate wireless communications [1–3]. However, the system performance may be degraded due to the processing delay at both the transmitter (TX) and the receiver (RX) in dynamic channels. Considering the delay in the channels, an effective approach in adaptive systems is to predict the channel values at the future data transmission time. We have proposed some channel prediction methods [4,5], and simulation results based on Jakes channel model [6] showed that MIMO ESDM systems using the methods outperformed the conventional unpredicted system in Rayleigh fading environments. In actual communications, scatterers may not be uniformly distributed around the RX and/or the TX, and MIMO systems may be used in Rician fading environments. Also, mutual coupling between antenna elements, which affects the MIMO system performance, could not be ignored. Therefore, more investigations into the system performance using the proposed methods in realistic cases are necessary. Most of the MIMO measurement campaigns have been conducted in time-invariant (i.e., Doppler frequency of 0 Hz) fading environments until now. However, due to mobile terminals’ and/or scatterers’ motion there will be time-varying fading in actual environments. So, measurement campaigns for such environments are very important. Unfortunately, to the best of our knowledge, just a few MIMO measurement campaigns assuming the environments have been conducted [7]. We conducted MIMO measurement campaigns in indoor time-varying fading environments. Based on the measured data, we evaluated the impact of the channel predictions on the performance of the 2×2 MIMO E-SDM system in actual dynamic channels.