WLC06-1: Capacity Measurements in a Multicell MIMO System

In future wireless networks, cooperation between the base stations may reduce the effects of intercell interference and enhance the capacity per cell. In this paper, the potential of such cooperation is evaluated using measurements of the information-theoretic channel capacity at 5.2 GHz in 4 overlapping urban macrocells with 5 users. In each link, a 10-transmit 16-receive antenna configuration is used. Results for individual links between terminals and base stations, valid for 60% of the scenarios, indicate that the direct signal has a significant impact on the channel structure. The direct signal contributes two spatial degrees of freedom due to the polarization. Rich scattering is observed when the direct signal is blocked. Results for the multiuser multicell scenario demonstrate for the first time experimentally that the intercell interference leads to an enhanced rank of the joint multiuser multicell channel matrix. Compared to a conventional cellular system, where a fixed assignment of different radio resources is used in adjacent cells in order to avoid the interference, it is better to exploit the interference by cooperation. This enhances the spectral efficiency by a factor of five in our measurement scenario.