Unequal error protection of data using trellis-coded modulation

A coding scheme that can provide different levels of error protection for different sets of bits in a transmitted symbol using trellis-coded modulation is presented. The scheme uses simple trellis code with 4-16 stages that are coupled with quadrature amplitude modulated (QAM) and asymmetrical QAM constellations. It has been found that the scheme can provide various levels of error protection for different sets of bits against channel impairments without much added complexity compared to the conventional trellis-coded modulation. The scheme also provides a design flexibility so that it is easily modified to accommodate different needs for error protection in various data transmission systems. A detailed design procedure and the performances of several unequal error protection codes are presented