Turbo-coding with staged data transmission and processing

A communications system, comprising:

• a transmitter comprising:
• a turbo-encoder for turbo-encoding source information, said turbo-encoder comprising a parallel concatenation of first and second convolutional codes, the turbo-encoder applying the first convolutional code to the source information to provide a first group of code bits, and applying the second convolutional code to the source information after interleaving the source information to provide a second group of code bits;
• a puncturing unit for puncturing the first and second groups of code bits;
• memory for storing the punctured first and second groups of code bits;
• said transmitter transmitting the first and second groups of non-punctured code bits via a channel to a receiver;
• the receiver comprising:
• memory for storing data samples corresponding to the first and second groups of non-punctured code bits;
• a turbo-decoder for turbo-decoding the data samples corresponding to the first and second groups of code bits in at least two decoding stages and determining whether the transmitted code bits have been received in error;
• upon detection of a transmission error, the turbo-decoder maintaining the data samples corresponding to the first and second groups of non-punctured code bits in memory and requesting transmission of at least a predetermined portion of the stored punctured code bits to the receiver, the turbo-decoder then turbo-decoding in at least two stages by combining the data samples corresponding to the first and second groups of non-punctured code bits with data samples corresponding to the transmitted punctured code bits.