OTFS channel estimation and detection for channels with very large delay spread

Preety Priya, Yi Hong, Emanuele Viterbo

Research output: Contribution to journalArticleResearchpeer-review

Abstract

In low latency applications and in general, for overspread channels, channel delay spread is a large percentage of the transmission frame duration. In this paper, we consider OTFS in an <italic>overspread</italic> channel exhibiting a delay spread that exceeds the block duration in a frame, where traditional channel estimation (CE) fails. We propose a two-stage CE method based on a delay-Doppler (DD) training frame, consisting of a dual chirp converted from time domain and a higher power pilot. The first stage employs a DD domain embedded pilot CE to estimate the aliased delays (due to modulo operation) and Doppler shifts, followed by identifying all the underspread paths not coinciding with any overspread path. The second stage utilizes time domain dual chirp correlation to estimate the actual delays and Doppler shifts of the remaining paths. This stage also resolves ambiguity in estimating delays and Doppler shifts for paths sharing same aliased delay. Furthermore, we present a modified low-complexity maximum ratio combining (MRC) detection algorithm for OTFS in overspread channels. Finally, we evaluate performance of OTFS using the proposed CE and the modified MRC detection in terms of normalized mean square error (NMSE) and bit error rate (BER).

Original languageEnglish
Number of pages11
JournalIEEE Transactions on Wireless Communications
DOIs
Publication statusAccepted/In press - 16 Apr 2024

Keywords

  • Channel estimation
  • channel estimation
  • Chirp
  • correlation
  • Delays
  • Doppler shift
  • dual chirp
  • MRC detection
  • OTFS
  • overspread delay
  • Training
  • Vectors
  • Wireless communication

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