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Sensors 2018, 18(4), 1280;

OFDM with Index Modulation for Asynchronous mMTC Networks

Department of Electrical and Electronics Engineering, Istanbul Medipol University, 34810 Istanbul, Turkey
Department of Electrical Engineering, University of South Florida, Tampa, FL 33620, USA
Author to whom correspondence should be addressed.
Received: 1 March 2018 / Revised: 13 April 2018 / Accepted: 19 April 2018 / Published: 21 April 2018
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One of the critical missions for next-generation wireless communication systems is to fulfill the high demand for massive Machine-Type Communications (mMTC). In mMTC systems, a sporadic transmission is performed between machine users and base station (BS). Lack of coordination between the users and BS in time destroys orthogonality between the subcarriers, and causes inter-carrier interference (ICI). Therefore, providing services to asynchronous massive machine users is a major challenge for Orthogonal Frequency Division Multiplexing (OFDM). In this study, OFDM with index modulation (OFDM-IM) is proposed as an eligible solution to alleviate ICI caused by asynchronous transmission in uncoordinated mMTC networks. In OFDM-IM, data transmission is performed not only by modulated subcarriers but also by the indices of active subcarriers. Unlike classical OFDM, fractional subcarrier activation leads to less ICI in OFDM-IM technology. A novel subcarrier mapping scheme (SMS) named as Inner Subcarrier Activation is proposed to further alleviate adjacent user interference in asynchronous OFDM-IM-based systems. ISA reduces inter-user interference since it gives more activation priority to inner subcarriers compared with the existing SMS-s. The superiority of the proposed SMS is shown through both theoretical analysis and computer-based simulations in comparison to existing mapping schemes for asynchronous systems. View Full-Text
Keywords: asynchronous transmission; massive Machine-Type Communication (mMTC); Orthogonal Frequency Division Multiplexing (OFDM); OFDM with Index Modulation (OFDM-IM) asynchronous transmission; massive Machine-Type Communication (mMTC); Orthogonal Frequency Division Multiplexing (OFDM); OFDM with Index Modulation (OFDM-IM)

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Doğan, S.; Tusha, A.; Arslan, H. OFDM with Index Modulation for Asynchronous mMTC Networks. Sensors 2018, 18, 1280.

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