Patent ID: 7920503

Claim:
A method for transmitting packets to mobile stations in a forward link of a multibeam satellite communication system, comprising the steps of: a multicarrier satellite system using a packet-switching method, wherein downlink beams of a satellite share a same orthogonal spreading code for transmitting packets to the mobile stations among beams by synchronizing and transmitting signals of all beams, and wherein downlink beams of the satellite have a frame structure that shares the orthogonal spreading codes among users, a) generating downlink beam signals by using an identical structure for frames transmitted through the downlink beams and an identical pseudo-noise (PN) scrambling code for generating downlink beam signals; and b) synchronizing transmission timing of frames, symbols and spread chips on the downlink beam signals wherein signals in the frame are transmitted by a plurality of subcarriers in the frequency domain, wherein part of the subcarriers in the frame are pilot subcarriers for transmitting pilot signals, which are separated from each other with a frequency spacing over the whole subcarriers so that the mobile station easily performs the channel estimation on a frequency-selective fading channel, wherein the pilot signals transmitted at the pilot subcarriers are signals obtained by spreading a predetermined pilot symbol sequence with an orthogonal pilot spreading code unique to each downlink beam; and wherein if the number of pilot spreading codes is less than the number of downlink beams, the same pilot spreading code is reused in downlink beams spaced apart in a predetermined distance and according to a predetermined reuse pattern for transmitting packets to mobile stations in the forward link of the multibeam satellite communication system.