Multiple access options for cellular based personal communications

The possible evolution of time division multiple access (TDMA) by, e.g., introducing frequency hopping and/or adaptive channel allocation, is described. The possibilities of direct sequence (DS) code division multiple access (CDMA) are considered. The different multiple access methods are examined. In particular, the concept of hierarchical cell structures is emphasized. The capacity depends on both the cell capacity and the ability to support hierarchical cell structures.