A UE of a wireless communication network first receives a modulation and coding scheme index IMCS for demodulating a physical layer data channel of the network. The UE then demodulates the physical layer data channel with a non-square quadrature amplitude modulation (NS-QAM) having a modulation order and code rate corresponding to a spectral efficiency (SPEFF) substantially equal to a SPEFF of a square QAM (S-QAM) SPEFF indicted by the IMCS, where the NS-QAM has an effective channel code rate no larger than the code rate for which the UE may skip decoding a transport block in an initial received transmission.