A study on adaptive modulation of data spread OFDM

An adaptive sub-carrier modulation in OFDM transmission is an effective scheme in order to increase transmission rate because it is possible for OFDM to determine a modulation scheme of each sub-carrier independently according to its channel state information. However, in this case, it is necessary to transmit allocation information of modulation from the transmitter to the receiver and this leads to degradation of performance. In this paper, an adaptive modulation scheme for OFDM that makes possible less information transmission from the transmitter to the receiver for allocation information is proposed. Moreover, sub-carrier power control is combined in order to improve performance further. As the result of theoretical analysis and simulation, better performance of the proposed scheme was confirmed.