Space, polarization, and angle diversity for cellular base stations operating in urban environments

Cellular telephone systems offer high reliability in favorable environments such as open rural areas. However, in urban areas and in rough terrain mobile and personal terminals experience multipath fading. Diversity techniques are used at the base station to overcome multipath fading. Although space diversity is the most common form of antenna diversity, it is the least attractive because it requires a second antenna widely separated from the first, as well as associated cable runs and installation costs. Interest has focused on polarization diversity that uses a single dual polarized antenna in place of two space diversity antennas. Angle diversity is also effective, but is not commonly employed. No direct, simultaneous comparisons of space, polarization, and angle diversity have been reported. Virginia Tech, sponsored by Metawave, is performing measurements of the three diversities under identical conditions. The measurements and results are described.