Broadband Measurement Analysis of Indoor Space-time Channels

Multiple-Input-Multiple-Output (MIMO) models often assume no correlation between the elements of the channel matrix. This assumption gives an indication on the upper bound of the channel capacity. However, in practice the channel capacity could decrease when the channels are correlated. In this paper, data measured using a 4x4 MIMO test-bed is processed to extract the spatial correlation in an office environment. In addition, probability density functions of signal strenghts, signal phases, and delay-spreads are measured. The test-bed that has been used is capable of simultaneously capturing 4 receive signals at 5.8 GHz (ISM band of IEEE 802.11a). The bandwidth of the signal is 20 MHz. A detailed description of the test-bed can be found at [1]. In section I, a model for the channel matrix correlation is introduced. This model is used to study the effect of correlation on capacity. In sections II and III the measurement set-up and results are presented.