A method of transmitting at least one data stream using superposition coding in a wireless communication system, the method comprising: receiving feedback information from at least two access terminals (ATs); assigning each of the at least two ATs as a first AT or a second AT based on the feedback information, wherein the first AT has a smaller path loss than that of the second AT, and the second AT has a larger path loss than that of the first AT; channel coding the at least one inputted data stream by a channel coding scheme; modulating the at least one data stream using layered modulation scheme; allocating wireless resources to symbols for the first AT and the second AT; and transmitting the symbols to at least one of the first AT and the second AT according to the allocated wireless resources, wherein the layered modulation scheme includes an inner layer and an outer layer, wherein at least one signal modulation constellation of the outer layer is rotated, wherein the first AT and the second AT are indicated by a control channel that is used to carry control information to the at least two ATs, wherein the control information includes a field for indicating a layer number of the layered modulation scheme and a field for indicating power level bits, the layer number corresponding one of the inner layer and the outer layer, wherein the layer number for the first AT is different from the layer number for the second AT, wherein a default transmit power level for each of the at least two ATs is indicated by the layer number for each of the at least two ATs, wherein the power level bits indicate a quantization level in relation to the default transmit power level for each of the at least two ATs. receiving feedback information from at least two access terminals (ATs); assigning each of the at least two ATs as a first AT or a second AT based on the feedback information, wherein the first AT has a smaller path loss than that of the second AT, and the second AT has a larger path loss than that of the first AT; channel coding the at least one inputted data stream by a channel coding scheme; modulating the at least one data stream using layered modulation scheme; allocating wireless resources to symbols for the first AT and the second AT; and transmitting the symbols to at least one of the first AT and the second AT according to the allocated wireless resources, wherein the layered modulation scheme includes an inner layer and an outer layer, wherein at least one signal modulation constellation of the outer layer is rotated, wherein the first AT and the second AT are indicated by a control channel that is used to carry control information to the at least two ATs, wherein the control information includes a field for indicating a layer number of the layered modulation scheme and a field for indicating power level bits, the layer number corresponding one of the inner layer and the outer layer, wherein the layer number for the first AT is different from the layer number for the second AT, wherein a default transmit power level for each of the at least two ATs is indicated by the layer number for each of the at least two ATs, wherein the power level bits indicate a quantization level in relation to the default transmit power level for each of the at least two ATs.