Impact On Performance
The spatial correlation (i.e., the eigenvalue spread in or ) has an impact on the performance of a multiantenna system. This impact can be analyzed mathematically by majorization of vectors with eigenvalues.
In information theory, the ergodic channel capacity represents the amount of information that can be transmitted reliably. Intuitively, the channel capacity is always degraded by receive-side spatial correlation as it decreases the number of (strong) spatial directions that the signal is received from. This makes it harder to perform diversity combining.
The impact of transmit-side spatial correlation depends on the channel knowledge. If the transmitter is perfectly informed or is uninformed, then the more spatial correlation there is the less the channel capacity. However, if the transmitter has statistical knowledge (i.e., knows and ) it is the other way around – spatial correlation improves the channel capacity since the dominating effect is that the channel uncertainty decreases.
The ergodic channel capacity measures the theoretical performance, but similar results have been proved for more practical performance measures as the error rate.
Read more about this topic: Spatial Correlation
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