Measured capacities at 5.8 GHz of indoor MIMO systems with MIMO interference

The capacity performances of two interfering flat-fading MIMO links are determined based on measured channels. Time-multiplexing of the links (TDMA), that is, when the MIMO links take turns operating without interference, serves as our baseline case. We compare this to the spatial-multiplexed case (SDMA), which allows both MIMO links to operate simultaneously. Under SDMA, both open-loop (no channel state information, CSI, is used at the transmitter) and closed-loop (CSI is used at the transmitter) operation are considered. Using data measured by virtual arrays, we explore the effects of line-of-sight (LOS), element spacing, correlated fading, and interference that has various levels of spatial correlation with the intended signal. Results show the benefit of wider element spacing in the channels without interference, especially when LOS is available, and with correlated interference if stream control is employed. However, wider spacing is hurtful if stream control is lacking.