Maximal Spectral Efficiency of OFDM with Index Modulation under Polynomial Space Complexity



In this letter, we demonstrate a mapper that enables all waveforms of OFDM with Index Modulation (OFDM-IM) while preserving polynomial time and space computational complexities. Enabling all OFDM-IM waveforms maximizes the spectral efficiency (SE) gain over the classic OFDM but, as far as we know, the computational overhead of the resulting mapper remains conjectured as prohibitive across the OFDM-IM literature. We show that the largest number of binomial coefficient calculations performed by the original OFDM-IM mapper is polynomial on the number of subcarriers, even under the setup that maximizes the SE gain over OFDM. Also, such coefficients match the entries of the so-called Pascal’s triangle (PT). Thus, by assisting the OFDM-IM mapper with a PT table, we show that the maximum SE gain over OFDM can be achieved under polynomial (rather than exponential) time and space complexities.


Computational Complexity, Index Modulation, Look-Up Table, OFDM, Pascal’s Triangle, Spectral Efficiency.

Related Project

5G - Components and Services for 5G Networks (5G - Componentes e Serviços para Redes 5G)


IEEE Wireless Communications Letters, January 2020

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Year 2020 : 1 citations

 P. Yang and F. Mu, "Outage Performance of Multi-Carrier Relay Selection for Full-Duplex OFDM with Index Modulation System," in IEEE Communications Letters. doi: 10.1109/LCOMM.2019.2956512