Capacity and power control in spread spectrum macro-diversity radio networks revisited

Macro-diversity - all base stations decode cooperatively each received signal - can mitigate shadow fading, and increase the capacity of a spread-spectrum communication network. Assuming that a terminal´s transmission power contributes to its own interference, the literature determines whether a vector of quality-of-service targets is feasible through a simple formula, which is insensitive to the terminals´ channel gains. Herein, through Banach´ contraction-mapping principle - and without the self-interference approximation - a new low-complexity capacity formula is derived. Through its dependence on relative channel gains, the new formula adapts itself in a sensible manner to special conditions, such as when most terminals can only be heard by a subset of the receivers. Under such conditions, the original may significantly overestimate capacity.