Measurement Survey on the Antenna Configuration Impact on the Spectral Efficiency of MIMO Radio Channels: Analyzed with a Focus on Low-Mobility, Indoor Line-of-Sight Channels

Abstract

Typical, large-scale as well as small-scale, in-room office scenarios are analyzed by broadband measurements with a fast MIMO channel sounder. A strong Line-of-Sight (LOS) signal component was always present, and the antenna arrays were arranged in particular ways to construct LOS channel matrices of different channel eigenvalue profiles. In this context, we particularly aim at investigating the practical relevance of high-rank LOS MIMO channel construction approaches in the presence of multipath signals. Statistical results are presented assuming the positions of transmitter and receiver being spatial random variables. To this end, new and appropriate performance measures are introduced in order to separate variations in receive power from alterations of the channel eigenvalue profile (CEP). Contrarily to widespread assumptions, the results show high spectral efficiencies also in deterministic LOS channels, as suboptimal eigenvalue profiles hardly occurred. This result seem to be widely independent from the antenna arrangement. Additionally, we investigate the impact of the transmission bandwidth on the variations of the spectral efficiency, showing broadband systems to be superior. Finally, we end up in several hints on related aspects of system design.