Universal frequency reuse: the CDMA advantage in capacity for digital cellular radio

Summary form only given, as follows. Interference among simultaneous users presents the primary limitation on capacity of all multiple access communication systems. In frequency-division-multiple-access (FDMA) and time-division-multiple-access (TDMA) cellular systems, interference is controlled by assigning disjoint frequency or time slots to all users in the same cell and disjoint frequency bands to adjacent cells, but to increase capacity, frequency bands are reused for sufficiently separated cells. These techniques lead to a hard limit on capacity and a tradeoff between frequency reuse and the C/I levels which can be tolerated. With direct sequence spread spectrum CDMA, frequency reuse is universal, with the same band utilized by all users over all cells with all user signals appearing as noise to all other users' receivers, progressively more attenuated with the distances involved. Careful analyses of both forward and reverse link interference lead to capacity estimates considerably higher than those for FDMA and TDMA systems, as well as a soft capacity limit unattainable with the more conventional systems.