Embedded coding technique: principles and theoretical studies

The principles of embedded array codes, which employ a combination of forward error correction and detection (FEC/FED) for error control in an ARQ environment, are introduced. In this scheme a concatenated code with an inner code for error correction and an outer code for error detection is used. A retransmission of the erroneous information packets is requested if the outer code decoder detects the presence of any errors after the initial correction has been performed by the inner decoder. The theoretical expressions for the reliability and throughput efficiency of the system are derived. The performance of the system is analysed and compared with that of a conventional array code. It is shown that the embedded scheme yields high reliability over a wide range of input bit error rates. A system of this type has many practical applications in situations where the transmission capacity of the communication channel varies with time; for example, on meteorburst or HF (2-30 MHz) radio links.