COMPARISON OF TDMA AND CDMA COMMUNICATION SYSTEMS.

A comparison is made between the capacity regions of time division multiple access (TDMA) and code division multiple access (CDMA) communication systems. The capacity regions for two users are calculated using a real adder channel model with additive white Gaussian noise. Only binary signal sets are considered in the CDMA case, while binary, ternary, and quaternary signals are considered for TDMA. Both discrete and continuous demodulator outputs are considered. A major result is that there exists some rate pairs and signal-to-noise ratios for which reliable communication is possible using binary CDMA but is not possible using any TDMA signaling scheme.