On Codes with Multi-level Error-correction Capabilities

In conventional coding for error control, all the information symbols of a message are regarcred equally significant, and hence codes are devised to provide equal protection for each information symbol against channel errors. are more significant than the other symbols. However, in some occasions, some information symbols in a message As a result, it is desired to devise codes with multi-level error-correcting capabilities. Another situation where codes with multi-level error-correcting capabilities are desired is in broadcast communication systems. An m-user broadcast channel has one input and m outputs. The single input and each output form a I component channel. The component channels may have different noise levels, I and hence the messages transmitted over the component channels require I different levels of protection against errors. In this research, we r investigate block codes with multi-level error-correcting capabilities, I which are also are known as unequal error protection (UEP) codes. structural properties of these codes are derived. Based on these structural properties, two classes of UEP codes are constructed. A subclass of codes