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Interleave.Division Multiple-Access(IDMA)iS an efficient multiple access technique tOimprove high spectrum efficiency for cellular communications.In this paper IDM-based modulation(called layered modulation(LM))is proposed for OFDM systems.The idea of LM is to multiplexmultiple parallel layers of data streams by performing repetition and layer-specific interleaver oneach layer.Since LM code bits are fully distributed in time-frequency plane,by the aid 0flow-complexity chip-by-chip interference cancellation time-frequency diversity Can be wellexploited in LM.Applying LM to 3GPP LTE downlink,we compare LM to M-PSK/QAMmodulation.Numerical results show that the LM Can achieve superior performance overM-PSK/QAM.The performance gain over QPSK,8PSK and 16QAM is 1.1dB,2.2dB and 0.6dB,respectively.