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Pre-Equalized Multi-User OTFS
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- Authors
- Junseok Kim, Chung-Sup Kim, Kwonhue Choi
- Issue Date
- 2026-02
- Citation
- IEEE Transactions on Wireless Communications, v.25, pp.11237-11252
- ISSN
- 1536-1276
- Publisher
- IEEE
- Language
- English
- Type
- Journal Article
- Abstract
- OTFS faces inter-symbol interference (ISI) due to delay and/or Doppler spreads, which requires compensation with an equalizer. In addition, in multiple access scenarios where users traverse distinct channels, OTFS also encounters multi-user interference (MUI). Hence, MUI is more challenging to mitigate than intra-user ISI and becomes more severe in high-mobility scenarios, where OTFS is typically deployed. This paper proposes a novel method called pre-equalized multi-user OTFS (PreEQ-MU-OTFS), which applies pre-equalization at the transmitter, using linear precoders for each user to fundamentally mitigate MUI. Specifically, the precoder is derived by initializing with the modified Wiener filter and employing a single step of iterative minimization. Additionally, the receiver in this method requires only per-user scaling, instead of full equalization. By leveraging the property of OTFS whereby fast-varying channels exhibit nearly time-invariant characteristics in the delay-Doppler (DD) domain, PreEQ-MU-OTFS performs effectively in high-mobility channels. The proposed method demonstrates superior bit error rate (BER) performance compared to conventional post-equalization receivers such as minimum mean square error (MMSE), MMSE-successive interference cancellation (MMSE-SIC), message passing (MP), and maximum-ratio combining (MRC) receivers. This method is validated in realistic channel scenarios with moving reflectors and practical channel aging levels.
- Keyword
- channel aging, linear precoding, multi-user interference, multiple access, OTFS
- KSP Keywords
- Bit Error rate, Channel aging, Fast-varying channels, Inter symbol interference(ISI), Iterative minimization, Linear precoders, MMSE-SIC, Message Passing, Minimum Mean Square Error(MMSE), Modified Wiener filter, Multiuser Interference(MUI)