In certain applications such as transmissions from spacecraft visiting distant planets, it is not sufficient to merely have codes that detect transmission errors when they arise; correction is required. Another example of a need for error-correcting codes is in live streaming video, where the frames are transmitted in sequence and displayed immediately. If a particular frame is distorted during transmission, then it must either be fixed by the receiver right then or else must be discarded completely (which however would result in image flicker or jitter for the viewer). Asking the source to resend a frame is not an option.

Therefore, in such cases as the above, given restrictions of distance, limited bandwidth or time, and other problems, it is extremely difficult to ask for a re-transmission of the data even if an error is detected. Therefore, a better protocol is needed where any errors that...