Array processing for wireless communications

By equipping the base stations of a wireless network with antenna arrays, it is possible to more fully exploit the spatial dimension in a wireless communication system. Multiple antennas can provide a processing gain to increase the base station range and improve coverage. Also, by exploiting the spatial selectivity of an antenna array, interference may be reduced which in turn can be traded for increased capacity of the system. A wide range of wireless communication systems may benefit from spatial processing including high mobility cellular systems, low mobility short range systems, wireless local loop applications, satellite communications and wireless LAN. By employing an array of antennas, it is possible to multiplex channels in the spatial dimension just as in the frequency and time dimension. This is often referred to as spatial division multiple access (SDMA). To increase system capacity, spatially selective reception as well as spatially selective transmission must be achieved. Herein, we present some different approaches and techniques for spatial/temporal processing. Critical aspects of SDMA for both high mobility cellular systems and low mobility or movable systems are reviewed and the potential benefits examined