1. A method of determining a signal to interference target ratio for operation of the outer loop of a power control system of a mobile communications system with a cellular infrastructure, wherein the ratio is determined based on a signal received from one of a base station and a mobile station of the mobile communications system, the method comprising: estimating the desired signal to interference ratio of the received signal; estimating the following statistical moments of the desired signal to interference ratio: typical deviation of the slow or lognormal fading component, typical deviation of the Gaussian distribution describing the joint statistical variation of all interfering signals, and, in the case of a direct beam existing between the emitter and the receiver, the Rice factor, comprising the quotient of the deterministic component and the random component of the desired signal; based on the estimated statistical moments and on a specification of the outage probability, calculating the margin of the desired signal to interference ratio by the Newton-Raphson iteration method; and determining the desired signal to interference target ration for the outer loop based on the calculated margin.