Spectral efficiency of FDMA/TDMA wireless systems with transmit and receive antenna arrays

The ever growing need for higher capacity in wireless systems has fueled the interest in exploiting the spatial dimension-through the use of antennas arrays-to improve the utilization of the available radio spectrum. As a result, a large number of space-time techniques have been proposed wherein arrays are used to mitigate interference and enhance signal levels. More recently, information theory has shown that, with spatial data multiplexing, very large spectral efficiencies can be attained in multipath channels using transmit and receive antenna arrays. In this paper, the system benefit of using transmit and receive arrays in multicell scenarios is evaluated as a function of both the propagation environment and the number of antennas. Our results confirm the potential for very large system spectral efficiencies associated with the use of transmit and receive arrays, in particular in interference-limited rich-multipath conditions wherein the ability to perform interference mitigation-leading to tighter spectral reuse-and spatial data multiplexing grows with the number of antennas. In environments free of multipath, the potential is smaller but still very significant, associated with interference mitigation and signal enhancement only, since spatial data multiplexing is no longer possible.