The effect of antenna correlation on the Multiple-Input Multiple-Output (MIMO) channel capacity in the real propagation environment is a topic of interest. In this paper, we present the results of a measurement campaign conducted in an indoor Line-Of-Sight (LOS) office environment. Channel responses were taken with varying distance in a static indoor environment. Results showed measurements with high received Signal-to-Noise Ratio (SNR) and a high level of correlation among the antenna elements. Further analysis of the results showed that MIMO systems can achieve sufficient channel capacity compared to the Single-Input Single-Output (SISO) system, despite high antenna correlation. Theoretical analysis reveals that when the SNR is sufficiently high, the loss in channel capacity due to high antenna correlation is relatively low. Therefore it is shown that in the indoor LOS environment, MIMO systems can be sufficiently efficient because the MIMO channel is more robust to antenna correlation when the SNR is high.