Initial characterisation or multiple-input multiple-output (MIMO) channels for space-time communication

Previous theoretical studies have demonstrated the substantial capacity or diversity gains possible when multi-element arrays are employed at both a transmitter and receiver. This is only possible when the radio channel exhibits sufficient scattering to induce independent fading at each receive element. An appreciation of both the temporal and spatial variation of such multiple-input, multiple-output (MIMO) channels is therefore required in order to investigate the performance of this architecture in real environments. In this paper we present initial results from indoor MIMO channel measurements taken within the coherence time of the channel. It is shown how capacity analysis of the MIMO channel response matrix alone can be misleading and how the combination of the variation of this with signal to noise ratio in real environments is particularly important.