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Optical OTFS is Capable of Improving the Bandwidth-, Power- and Energy-Efficiency of Optical OFDM
- Source :
- IEEE Transactions on Communications; February 2024, Vol. 72 Issue: 2 p938-953, 16p
- Publication Year :
- 2024
-
Abstract
- We demonstrate that the proposed optical orthogonal time frequency space (O-OTFS) is capable of improving the bandwidth-/power-/energy-efficiencies of optical orthogonal frequency-division multiplexing (O-OFDM). The bandwidth-efficiency is improved because only a single cyclic prefix (CP) is needed for an entire O-OTFS frame. The power-efficiency is enhanced thanks to the diversity gain achieved by its symplectic finite Fourier transform (SFFT), which also leads to a reduced peak-to-average power ratio (PAPR), hence improving its energy-efficiency. These features are facilitated by the proposed layered asymmetrically clipped O-OTFS (LACO-OTFS), which is capable of removing the direct current (DC) bias while retaining the full optical throughput. Nonetheless, there exists an inherent trade-off, where increasing the O-OTFS frame size leads to a commensurately reduced CP percentage at the cost of an increased PAPR. In order to mitigate this, we propose to perform discrete Fourier transform based spreading (DFT-S) in the delay-Doppler (DD)-domain. Furthermore, we demonstrate that regardless of the choice of domain in which the information is modulated (i.e. O-OFDM/O-OTFS with/without DFT-S), the frequency-selectivity of the quasi-static but dispersive optical channel can always be equalized by single-tap frequency-domain equalization (FDE). Moreover, the channel estimation techniques are conceived to operate in the time-/frequency-/DD-domains for both O-OFDM and O-OTFS. Our simulation results demonstrate that for a multi-user optical wireless system associated with <inline-formula> <tex-math notation="LaTeX">$M=64$ </tex-math></inline-formula> subcarriers and the OTFS frame length of <inline-formula> <tex-math notation="LaTeX">$N=64$ </tex-math></inline-formula>, LACO-OTFS is capable of achieving a 7 dB power-efficiency gain over LACO-OFDM, where the CP overhead is reduced by a factor of <inline-formula> <tex-math notation="LaTeX">$N=64$ </tex-math></inline-formula>. DFT-S-LACO-OTFS is also capable of providing a 7 dB power-efficiency gain over DFT-S-LACO-OFDM, where the low PAPR of single-carrier transmission is retained.
Details
- Language :
- English
- ISSN :
- 00906778 and 15580857
- Volume :
- 72
- Issue :
- 2
- Database :
- Supplemental Index
- Journal :
- IEEE Transactions on Communications
- Publication Type :
- Periodical
- Accession number :
- ejs65561810
- Full Text :
- https://doi.org/10.1109/TCOMM.2023.3326494