Patent ID: 6263466
Filing Date: 2001-07-17
Classification: H03M,H04B,H04L,Y02D

Abstract:
A data communication system for a communication network comprising a constellation of low-Earth orbit (LEO) satellites and ground terminals for sending data packets to and receiving data packets from the low-Earth orbit satellites forming said constellation, said data packets including header databits and payload databits, said header databits including information regarding the destination of the payload databits, said data communication system comprising:a forward error correction (FEC) coding system located in said ground terminals for: (i) separately outer FEC encoding the header and payload databits of said data packets; (ii) separately inner FEC encoding said outer encoded header and payload codewords to produce concatenated coded header and payload codewords; (iii) mixing said concatenated coded header and payload codewords to produce concatenated coded data packets; and (iv) transmitting said concatenated coded data packets to one of said low-Earth orbit satellites;an FEC decoding system located in said low-Earth orbit satellites for: (i) receiving said concatenated coded data packets; (ii) demixing said concatenated coded data packets to recover said concatenated coded header and payload codewords; (iii) decoding said concatenated coded header codewords to recover said outer encoded header codewords; (iv) outer decoding said header codewords to recover said header databits; (v) separating said concatenated coded payload codewords to recover concatenated coded payload codewords intended for the satellite receiving said concatenated coded data packets; (vi) decoding said concatenated coded payload codewords intended for the satellite receiving said concatenated coded data packets, but not other concatenated coded payload codewords, to recover outer encoded receiving satellite payload codewords; (vii) outer decoding said receiving satellite payload codewords to recover said receiving satellite payload databits; and (viii) making a hard decision on the bits of said other concatenated coded payload codewords;an FEC coding system located in said low-Earth orbit satellites for: (i) receiving from other satellites data packets comprising header databits and concatenated coded payload codewords intended for one of said ground terminals; (ii) re-outer FEC encoding the header databits received from other satellites; (iii) re-inner FEC encoding said re-outer encoded header codewords to produce re-concatenated coded header codewords; (iv) mixing said re-concatenated coded header codewords and said concatenated coded payload codewords intended for one of said ground terminals to produce re-concatenated coded data packets; and (v) transmitting said re-concatenated coded data packets to one of said ground terminals; andan FEC decoding system located in said ground terminals for: (i) receiving said re-concatenated coded data packets; (ii) demixing said re-concatenated coded data packets to recover said re-concatenated coded header codewords and said concatenated coded payload codewords; (iii) separately inner decoding said re-concatenated coded header codewords and said concatenated coded payload codewords to recover said re-outer encoded header and outer encoded payload codewords; and (iv) separately outer decoding said header and payload codewords to recover said header and payload databits.