Enhanced index modulation aided orthogonal time frequency space with variable active grids and multiple constellations

Zhang, K, Jiang, X-Q, Hai, H, Qiu, R and Mumtaz, S ORCID: https://orcid.org/0000-0001-6364-6149, 2024. Enhanced index modulation aided orthogonal time frequency space with variable active grids and multiple constellations. IEEE Transactions on Vehicular Technology. ISSN 0018-9545

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Abstract

Present orthogonal time frequency space modulation with index modulation (OTFS-IM) techniques activate a given number of grids in the delay-Doppler (DD) domain and employ fixed constellation as changing them would result in ambiguous detection. Motivated by this, we propose a novel enhanced OTFS with index modulation (E-OTFS-IM) scheme which permits changing the number of active grids conveying modulation symbols from any constellation. The proposed E-OTFS-IM scheme alleviates ambiguous detection by jointly mapping information to grid activation pattern in DD domain and 2D modulation symbols. We also propose an efficient encoding method for E-OTFS-IM. In addition, an updated message passing (MP) detection suitable for E-OTFS-IM as well as its low-complexity improvement are developed. We derive a average bit error probability (ABEP) upper bound for our proposed E-OTFS-IM scheme employing the maximum likelihood detector. Additionally, we also propose an enhanced scheme named E-OTFS-IM with in-phase/quadrature (E-OTFS-IM-IQ) to further improve the spectral efficiency and reliability. In E-OTFS-IM-IQ, the principle of E-OTFS-IM is extended to in-phase and quadrature branches independently. The efficient encoding method and MP detector for this modified scheme is also introduced. Simulation results confirm that the derived ABEP upper bound is tight in the high signal-to-noise ratio region, and show that our proposed E-OTFS-IM improves the performance of conventional OTFS and OTFS-IM. The results also indicate the proposed E-OTFS-IM-IQ achieves better bit error rate performance than E-OTFS-IM.

Item Type:	Journal article
Publication Title:	IEEE Transactions on Vehicular Technology
Creators:	Zhang, K., Jiang, X.-Q., Hai, H., Qiu, R. and Mumtaz, S.
Publisher:	Institute of Electrical and Electronics Engineers (IEEE)
Date:	7 March 2024
ISSN:	0018-9545
Identifiers:	Number Type 10.1109/tvt.2024.3373591 DOI 1872879 Other
Rights:	© 2024 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
Divisions:	Schools > School of Science and Technology
Record created by:	Jeremy Silvester
Date Added:	27 Mar 2024 09:13
Last Modified:	27 Mar 2024 09:13
URI:	https://irep.ntu.ac.uk/id/eprint/51165

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