On the effect of adjacent GSM system to FDSS uplink capacity

One of the main challenges when implementing the future mobile multimedia networks is the cost effective network evolution from second to third-generation systems. This evolution may include the use of different technologies at the same frequency band. In this paper, the performance of the frequency diversity spread spectrum (FDSS) uplink is studied in the case when there is GSM interference sources in the adjacent frequency. A simple analytical method which study the effect of the adjacent GSM on the uplink capacity of the FDSS system is studied assuming collocated base stations of both systems. The FDSS transmitter and receiver models are shown. A model to calculate the interference as a function of the GSM users is presented. Some numerical examples are given. It is noticed that the interference effect is high for frequency separation of 1820 KHz or less. The effect of the GSM system is quasi null when the frequency separation is higher than 2250 KHz.