A spectrally efficient OFDM-based modulation scheme for future wireless systems

Abstract

A novel modulation technique termed as orthogonal frequency division multiplexing with subcarrier power modulation (OFDM-SPM) for efficient data transmission in wireless communication systems is proposed. OFDM-SPM uses the power of each subcarrier in an OFDM block as a third dimension to carry data, where different power levels correspond to different bits. In this paper, the concept of OFDM-SPM is applied to conventional OFDM using binary phase shift keying (BPSK) symbol modulation over an additive white Gaussian noise channel (AWGN). The system and its validity as a future adopted modulation technique is investigated, where a general overview of the system is given. Simulation results regarding the bit error rate (BER) and the throughput of the system are displayed, and the merits of this scheme are discussed. Results show that compared to other proposed modulation techniques which add a third dimension to carry data, OFDM-SPM vastly improves spectral efficiency, where it is capable of doubling the spectral efficiency in addition to reducing the transmission power of the system by half. Although this results in a degradation in the system bit error rate performance, the scheme suggests that this can be overcome by reallocating the saved power to the transmitted OFDM subcarriers.