SERIAL UNEQUAL ERROR-PROTECTION CODES BASED ON TRELLIS-CODED MODULATION

Unequal error-protection (UEP) codes that are designed using trellis-c oded modulation (TCM) are proposed for use with a single data stream c onsisting of information with two levels of importance. To achieve UEP , the proposed scheme encodes the data according to the importance of the information by switching between two codes which use different sig nal constellations. Using simple trellis codes, it is shown that the e rror rate of the important information is lower than the error rate fo r an equivalent equal error-protection scheme.