Dimensioning of spread spectrum systems for ISDN

We deal with wireless local loop (WLL) systems using spread spectrum techniques to provide integrated services digital networks (ISDN) local access. We consider the dimensioning of a base station intended to serve various ISDN subscribers. The connection between subscribers and base station is achieved via the atmospheric channel and the transmission technique used is direct sequence spread spectrum (DS-SS). An expression that permits the calculation of the maximum number of users that a base station can serve in providing the desired quality of service (QoS) and the mean traffic per user is derived. Based on this formulation we present numerical results, on the QoS for values of the bit error probability required by an ISDN and the typical mean traffic of this kind of application.