Measure, Simulation and Spectral Efficiency Analysis for MIMO Channels in Indoor Environments over the 2GHz Band

Abstract

The space-time wireless communication systems will use the advantages of the MIMO (Multiple Input Multiple Output) channels. Precedent studies have focused less attention on the capacity analysis considering correlated indoor channels under different frequency bands and polarizations. In practice, there is certain correlation degree between the different propagation sub-channels, which makes interesting to evaluate the impact that this correlation has on the system performance under different frequency bands and polarizations.

The paper shows a detail study around of real MIMO channel and its spectral efficiency behavior when change both the number of antenna elements and SNR (Signal to Noise Ratio). The results showed in the paper demonstrate that to increase the diversity order could not be a good technique to improve the performance of the MIMO systems in some highly correlated cases when picocells or indoor environments are considered. Besides, increasing the number of array antenna elements, both in the transmitter and receiver side, does not offer linear capacity increases under correlated cases. The results derived from a frequency measurement campaigns performed between 2 and 2.6 GHz show polarization dependence and less frequency band dependence in the MIMO channel correlation matrix for indoor environments.

In other hand, under the WSS (Wide Sense Stationary) channel condition and guaranteeing a minimum SNR level, remarkable changes on the capacity probability distribution function shape, and on the cumulative distribution function of the MIMO system eigenvalues, were observed in different correlated cases.