Incorporation of uplink channel state information into an end-to-end coded satellite communication system

Satellite communications systems employing forward error correction (FEC) codes are simplified when the code is applied at the source´s transmitter and removed at the end user´s receiver (end-to-end coding), avoiding decoding and re-encoding on board the satellite. Channel capacity can be approached when channel state information from the uplink is incorporated into the soft information input to the downlink decoder. For fading channels, the channel state information is time-varying and must be updated frequently. This paper will describe techniques for both measuring and incorporating practical, bandwidth efficient uplink channel state information in an end-to-end coded satellite communications system. Link performance with and without channel state information will be compared. A technique for estimating channel state information will also be analyzed.