Flexible LED Index Modulation for MIMO Optical Wireless Communications

Anil Yesilkaya, Ardimas Andi Purwita, Erdal Panayirci, H. Vincent Poor, Harald Haas

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


The limited bandwidth of optical wireless communication (OWC) front-end devices motivates the use of multipleinput- multiple-output (MIMO) techniques to enhance data rates. It is known that very high multiplexing gains can be achieved by spatial multiplexing (SMX) at the cost of prohibitive detection complexity. Alternatively, in spatial modulation (SM), a single light emitting diode (LED) is activated per time instance where information is carried by both the signal and the LED index. Since only one LED is active, both the transmitter (TX) and receiver (RX) complexity reduce significantly while retaining the information transmission in the spatial domain. However, this simplified TX utilization approach leads SM to suffer from significant spectral efficiency losses compared to SMX. In this paper, we propose a technique that benefits from the advantages of both systems. Accordingly, the proposed flexible LED index modulation (FLIM) technique harnesses the inactive state of the LEDs as a transmit symbol. Therefore, the number of active LEDs changes in each transmission, unlike conventional techniques. Moreover, the system complexity is reduced by employing a linear minimum mean squared error (MMSE) equalizer and an angle perturbed receiver. Numerical results show that FLIM outperforms the reference systems by at least 6 dB in the low and medium/high spectral efficiency regions.

Original languageEnglish (US)
Article number9322528
JournalProceedings - IEEE Global Communications Conference, GLOBECOM
StatePublished - 2020
Externally publishedYes
Event2020 IEEE Global Communications Conference, GLOBECOM 2020 - Virtual, Taipei, Taiwan, Province of China
Duration: Dec 7 2020Dec 11 2020

All Science Journal Classification (ASJC) codes

  • Artificial Intelligence
  • Computer Networks and Communications
  • Hardware and Architecture
  • Signal Processing


  • minimum mean square equalizer (MMSE)
  • multiple-input-multiple-output (MIMO)
  • Optical wireless communications (OWC)
  • spatial modulation (SM)


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