The unequal error protection of multilevel coded modulation based on capacity rule in Rayleigh fading channels is investigated.After the unequal error protection of multilevel coded modulation is discussed in detail
a non-uniform signal constellation applied to 8ASK modulation is designed.Both theoretical analysis and computer simulation show that non-uniform signal constellation can improve unequal error protection ability of multilevel coded modulation system.It improves transmission quality in Rayleigh fading environment and saves bandwidth at the same time.