Iterative signal detection under timing errors for optical wireless links with high mobility

M. T. Dabiri, S. Khankalantary, H. Safi, Md J. Piran, I. S. Ansari, D. Y. Suh, M. Uysal

Research output: Contribution to journalArticlepeer-review


In this paper, the problem of timing error for freespace optical links with high mobility is investigated. In particular, we consider a real scenario in which the sampling clock offset is randomly changing and, in addition, the receiver has no information about the instantaneous channel coefficient as well as instantaneous timing error. Moreover, we consider a general case with signal dependent noise. For the considered scenario, for a conventional receiverwith one sampler, we propose an iterative detectionmethod based on the expectation-maximization (EM) algorithm. In the presence of large values of sampling clock offset, shifted error is the dominant error. Hence, in order to reduce the impact of shifted error probability, we propose an iterative data detection method for a receiver which utilizes two shifted samplers. The proposed iterative detection method only requires a series of simple addition and multiplication operation and does not require to solve any integral equations. A set of simulation results are provided to study the system performance for the proposed detectionmethods. Simulation results demonstrate that for a receiver with two samplers, by using the proposedEM-based detector,we can achieve bit error rate performance very close to the ideal receiver that perfectly knows the instantaneous channel coefficient and sampling clock offset.

Original languageEnglish (US)
Pages (from-to)11710-11720
Number of pages11
JournalIEEE Transactions on Vehicular Technology
Issue number11
StatePublished - Nov 1 2021


  • Atmospheric turbulence
  • Blind data detection
  • Differential signaling
  • Free-space optics
  • Synchronization

ASJC Scopus subject areas

  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Computer Networks and Communications
  • Automotive Engineering


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