Combined CDMA with TDMA increases the capacity of a cellular communication system

The authors present a novel cell structure that combines the qualities of code division multiple access (CDMA) and time division multiple access (TDMA) to reduce cochannel interferences. The cell consists of a centrally located base station with eight surrounding corner antennas. The mobiles and antennas operate in a TDMA mode and the communication channels employ spread spectrum direct sequence modulation. TDMA combined with the spatial separation of the cell antennas reduces the carrier-to-interference ratio and thereby increases the cell capacity. The capability and cochannel interference for both forward and reverse link of the proposed system are computed and compared with that of the traditional CDMA cellular system. The results show that the capacity of the proposed system in the forward link is increased by an average factor of three over the traditional CDMA cellular system. For the reverse link the capacities of the systems are comparable