Patent ID: 7162682

Claim:
A method of error control coding and decoding of messages in a packet-based data transmission system, where each message comprises a header, which includes frame length information, a data portion and a frame check sequence, comprising the steps of: at a transmitting device: a) receiving said message including the header, the data portion and the frame check sequence and inserting gaps into the data portion and the frame check sequence of the frame, b) updating the length information of the header to reflect the length of the frame including the gaps and a future outer frame check sequence, c) applying a scrambling algorithm to at least part of the frame, d) applying a forward error correction algorithm to at least part of the frame scrambled in step c) to generate forward error correction data, e) inserting the generated forward error correction data into the gaps, f) generating a scrambled outer frame check sequence and including the scrambled outer frame check sequence in the frame, g) transmitting the scrambled frame with the forward error correction data and the outer frame check sequence, at a receiving device: h) receiving the scrambled frame with the forward error correction data and the scrambled outer frame check sequence, i) checking whether or not the scrambled outer frame check sequence is correct, j) if yes, removing the outer frame check sequence, removing the forward error correction data, descrambling the frame, removing the gaps, and updating the length information of the header to its original value, k) if no, removing the outer frame check sequence, applying an error correction algorithm based on the inserted forward error correction data to at least part of the remainder of the frame, removing the inserted forward error correction data, descrambling the frame, removing the inserted gaps, and updating the length information of the header to its original value.