A multi-beam system is one solution for enlarging the communication capacity by re-using the limited system frequency band, but system resources should be allocated to each user considering the interferences from vicinity beams(users). In addition, in mobile satellite systems, the resource allocation must consider user mobility and the uneven user distribution in the system and each beam. In this paper, we analyze an FDMA based multi-beam satellite system resource allocation scheme that considers both inter-beam interference and user distribution in the system in controlling both forward link power and frequency simultaneously. We confirm that this scheme enhances system capacity relative to the CDMA system, which uses the entire system frequency band.