====== Work Summary =====
The emergence of the internet of things (IoT) imposes meeting several harsh requirements simultaneously such as high spectral efﬁciency, low-complexity, and sufﬁcient transmission reliability. In this paper, we present a two-dimensional modulation format termed orthogonal frequency division multiplexing with subcarrier power modulation and differential phase-shift keying (OFDM-SPM-DPSK) where the power of the subcarriers in an OFDM block is explored as a second dimension for sending data, without devoting any bandwidth solely for this purpose. In this design, two streams of data are modulated separately; where a stream of data is sent through the classical symbol constellations of DPSK, and a second stream is conveyed through the power subcarriers’ levels. The proposed design results in doubling the spectral efﬁciency and ensures low design complexity due to its non-coherence. Moreover, due to its 2-D format, this modulation setup offers ﬂexibility regarding the usage of the transmit power where, for the same transmission compared to OFDM, half the power can be saved. This saved power can be reassigned to the transmit subcarriers for enhancing the system’s reliability. Particularly, in this manuscript, we treat a speciﬁc problem regarding the reassignment of the power to the transmit subcarriers where we show that the proposed OFDM-SPM-DPSK can be used to achieve the performance of coherent OFDM-BPSK, under proper reassignment mechanism.