High reuse efficiency of radio resources in urban microcellular systems

A new microcell configuration scheme in urban areas is proposed in order to increase the reuse efficiency of radio resources. Multiple directional-beam antennas lined up along a street form a cigar-shaped cell. Antennas are located at intersection and are directed along the intersecting streets. Two antennas facing each other form a microzone and, therefore, a cigar-shaped cell consists of multiple microzones in a line. Each microzone is protected against cochannel interference from neighboring microzones by confinement of transmitted signals to a microzone using down-tilting of antenna beams. Therefore, a radio channel which is occupied in one microzone can be used in adjacent microzones. An increase in system capacity is achieved by the high reuse efficiency of radio resources. The proposed system increases system capacity up to 560% with a call blocking probability of 1% when compared with a conventional system. In addition, a macrodiversity scheme using two antennas in a microzone improves the call quality on the reverse link