Indoor MIMO channel measurements using dual polarized patch antennas

A mobile 4×4 multiple input multiple output (MIMO) system containing dual polarized patch antennas is used to perform wireless measurement campaigns on nonline of sight (NLOS) channels in an indoor office setting. The MIMO system uses orthogonal 500 kchips/s Walsh coded signals that are filtered and simultaneously transmitted at 916 MHz. The patch antennas have high isolation between their two ports and are used at both transmitter and receiver stations. The complex MIMO channel matrices obtained in the campaigns were used to calculate the theoretical capacity for a 4×4 system. Our mean measured capacity for the campaign is 21.3 bits/use and the 90^th percentile channel capacity is 19.5 bits/use. These values are slightly higher than those (mean of 21.1 bits/use and 90^th percentile channel capacity of 18.9 bits/use) obtained for an identical campaign which used single polarized whip antennas.