Common downlink frame for differing coding rates

A method of organizing a plurality of data cells into a fixed size frame for transmission in the downlink of a processing satellite to at least one of a plurality of earth terminals, comprising the steps of:

• determining an inner coding rate for a first set of data cells;
• forming a group of codewords by applying an outer code to said set of data cells, such that the said group of codewords being proportional to said inner coding rate;
• entering said group of codewords row wise into an interleaving array;
• and
• applying an inner code column wise to said group of codewords, thereby forming a fixed size frame.

A data communication system for transmitting a fixed size frame in a downlink from a processing satellite to at least one of a plurality of earth terminals, comprising:

• a means for determining an inner coding rate for downlinking a set of data cells to a first earth terminal, said inner coding rate being based on a characteristic of said first earth terminal;
• a first encoder for forming a group of codewords by applying an outer code to said set of data cells, such that the group of codewords being proportional to said inner coding rate;
• a means for entering said group of codewords row wise into an interleaver array;
• and
• a second encoder for applying an inner code column wise to said group of codewords, thereby forming a fixed size frame.