Disclosed are techniques related to wireless communication system in which multi-level encoded modulation (MLCM) is applied to non-coherent communication. In the proposed techniques, a small fraction of differential phase rotations or bits participating in differential symbol coding are protected with strong codes while other complementary differential phase rotations or bits are protected with weaker codes. Compared to conventional non-coherent communication techniques in which a uniform protection is applied to any fraction of differential phase rotation or any bit of a differential symbol, the proposed MLCM approach enables more spectrally efficient scheme.