Abstract: This paper studies capacity of CDMA or FDMA/TDMA for multi-beam geostationary earth orbit (GEO) satellite communication systems. Relation is derived between outage probability of the required SNR and the number
of users support at a given power control error (PCE) level and voice activity factor. An expression of capacity of multi-beam GEO CDMA system is then obtained. Numerical results show that capacity is sensitive to system
parameters such as PCE. Using power and continuous phase modulation (CPM), capacity of FDMA/TDMA system is obtained according to the spectral efficiency of CPM. Comparison between CDMA and FDMA/TDMA shows that
capacity of FDMA/TDMA system is larger than CDMA in multi-beam GEO systems.

Key words: multi-beam GEO satellite communication, CDMA, FDMA, power control error (PCE)