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Modulation Options for OFDM-Based Waveforms: Classification, Comparison, and Future Directions

January 2019
IEEE Access PP(99):1-1

DOI:10.1109/ACCESS.2019.2895958

License
CC BY-NC-ND 4.0

Authors:

Ahmad Jaradat

Irbid National University

Jehad M. Hamamreh

Antalya Bilim University

Huseyin Arslan

University of South Florida & Istanbul Medipol University

This paper provides a comparative study on the performance of different modulation options for orthogonal frequency division multiplexing (OFDM) in terms of their spectral efficiency, reliability, peak-to-average power ratio, power efficiency, out-of-band emission, and computational complexity. The modulation candidates are classified into two main categories based on the signal plane dimension they exploit. These categories are: 1) 2-D signal plane category including conventional OFDM with classical fixed or adaptive QAM modulation and OFDM with differential modulation, where information is conveyed in changes between two successive symbols in the same subcarrier or between two consecutive subcarriers in the same OFDM symbol and 2) 3-D signal plane category encompassing: a) index-based OFDM modulation schemes which include: i) spatial modulation OFDM, where information is sent by the indices of antennas along with conventional modulated symbols and ii) OFDM with index modulation, where the subcarriers' indices are used to send additional information; b) number-based OFDM modulation schemes which include OFDM with subcarrier number modulation, in which number of subcarriers is exploited to convey additional information; and c) shape-based OFDM modulation schemes which include OFDM with pulse superposition modulation, where the shape of pulses is introduced as a third new dimension to convey additional information. Based on the provided comparative study, the relationship and interaction between these different modulation options and the requirements of future 5G networks are discussed and explained. This paper is then concluded with some recommendations and future research directions.

SM-OFDM transmitter.

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3-D signal plane of the SM-OFDM scheme.

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3-D signal plane of the OFDM-SNM scheme.

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Conventional Gaussian transmission (upper part of the figure) vs. pulse superposition modulation using Hermite Gaussian pulses (lower part of the figure). It is noticed that four data symbols can be carried by PSM within a duration (or bandwidth) equal to that occupied by two adjacent Gaussian pulses by which only two data symbols can be carried.

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Throughput of the featured modulation options of OFDM.

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Figures - uploaded by Ahmad Jaradat

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Available via license: CC BY-NC-ND 4.0

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