Experimental investigation of multipath richness for multi-element transmit and receive antenna arrays

The multi-element antenna arrays concept with M elements at the mobile station (MS) in combination with N elements at the base station (BS) is experimentally investigated. Forschini (1996) has shown very promising results to improve the spectral efficiency in a rich scattering environment. The performance of the M×N concept is evaluated in terms of the number of independent parallel channels, diversity gain and total capacity in an outdoor to indoor microcellular environment. It is shown that the eigenanalysis provides a tool to describe the effective number of parallel channels in a multi-element array configuration. Practical results on spectral efficiency are presented for different antenna setups applied to different propagation scenarios. Also it is shown that polarization diversity is an attractive solution to achieve decorrelated antenna elements and subsequently provide a more robust system in terms of spectral efficiency within the microcell. Results show that a total capacity of 27.9 b/s/Hz can be achieved for an uncorrelated propagation environment and 17 b/s/Hz for a correlated one with a mean signal to noise ratio (SNR) of 30 dB in the case of a 4×4 antenna set-up