Recent Publications
2024
Safi, Hossein; Dabiri, Mohammad Taghi; Cheng, Julian; Tavakkolnia, Iman; Haas, Harald
CubeSat-Enabled Free-Space Optics: Joint Data Communication and Fine Beam Tracking Miscellaneous
2024, (Version Number: 1).
Abstract | Links | BibTeX | Tags: electronic engineering, FOS: Computer and information sciences, FOS: Electrical engineering, information engineering, Information Theory (cs.IT), LRDC, Signal Processing (eess.SP)
@misc{safi_cubesat-enabled_2024-1,
title = {CubeSat-Enabled Free-Space Optics: Joint Data Communication and Fine Beam Tracking},
author = {Hossein Safi and Mohammad Taghi Dabiri and Julian Cheng and Iman Tavakkolnia and Harald Haas},
url = {https://arxiv.org/abs/2406.18598},
doi = {10.48550/ARXIV.2406.18598},
year = {2024},
date = {2024-01-01},
urldate = {2024-10-30},
publisher = {arXiv},
abstract = {The integration of CubeSats with Free Space Optical (FSO) links accelerates a major advancement in high-throughput, low-Earth orbit communication systems. However, CubeSats face challenges such as size, weight, and power (SWaP) limitations, as well as vibrations that cause fluctuations in the angle-of-arrival (AoA) of the optical beam at the receiver. These practical challenges make establishing CubeSat-assisted FSO links complicated. To mitigate AoA fluctuations, we expand the receiver's field of view and track the location of the focused beam spot using an array of avalanche photodiodes at the receiver. Initially, we model the optical channel between the transmitter and the detector array. Furthermore, to reduce the computational load of maximum likelihood sequence detection, which is infeasible for CubeSats due to SWaP constraints, we propose a sub-optimal blind sequence data detection approach that relies on the generalized likelihood ratio test (GLRT) criterion. We also utilize combining methods such as equal gain combining (EGC) and maximal ratio combining (MRC) for data detection, benchmarking their performance against the GLRT-based method. Numerical results demonstrate that the proposed low-complexity GLRT-based method outperforms the combining methods, achieving performance close to that of the ideal receiver.},
note = {Version Number: 1},
keywords = {electronic engineering, FOS: Computer and information sciences, FOS: Electrical engineering, information engineering, Information Theory (cs.IT), LRDC, Signal Processing (eess.SP)},
pubstate = {published},
tppubtype = {misc}
}
The integration of CubeSats with Free Space Optical (FSO) links accelerates a major advancement in high-throughput, low-Earth orbit communication systems. However, CubeSats face challenges such as size, weight, and power (SWaP) limitations, as well as vibrations that cause fluctuations in the angle-of-arrival (AoA) of the optical beam at the receiver. These practical challenges make establishing CubeSat-assisted FSO links complicated. To mitigate AoA fluctuations, we expand the receiver's field of view and track the location of the focused beam spot using an array of avalanche photodiodes at the receiver. Initially, we model the optical channel between the transmitter and the detector array. Furthermore, to reduce the computational load of maximum likelihood sequence detection, which is infeasible for CubeSats due to SWaP constraints, we propose a sub-optimal blind sequence data detection approach that relies on the generalized likelihood ratio test (GLRT) criterion. We also utilize combining methods such as equal gain combining (EGC) and maximal ratio combining (MRC) for data detection, benchmarking their performance against the GLRT-based method. Numerical results demonstrate that the proposed low-complexity GLRT-based method outperforms the combining methods, achieving performance close to that of the ideal receiver.
Kazemi, Hossein; Sarbazi, Elham; Crisp, Michael; El-Gorashi, Taisir E. H.; Elmirghani, Jaafar M. H.; Penty, Richard V.; White, Ian H.; Safari, Majid; Haas, Harald
A Novel Terabit Grid-of-Beam Optical Wireless Multi-User Access Network With Beam Clustering Miscellaneous
2024, (Version Number: 1).
Abstract | Links | BibTeX | Tags: electronic engineering, FOS: Electrical engineering, information engineering, LRDC, Signal Processing (eess.SP)
@misc{kazemi_novel_2024b,
title = {A Novel Terabit Grid-of-Beam Optical Wireless Multi-User Access Network With Beam Clustering},
author = {Hossein Kazemi and Elham Sarbazi and Michael Crisp and Taisir E. H. El-Gorashi and Jaafar M. H. Elmirghani and Richard V. Penty and Ian H. White and Majid Safari and Harald Haas},
url = {https://arxiv.org/abs/2404.04443},
doi = {10.48550/ARXIV.2404.04443},
year = {2024},
date = {2024-01-01},
urldate = {2024-10-30},
publisher = {arXiv},
abstract = {In this paper, we put forward a proof of concept for sixth generation (6G) Terabit infrared (IR) laser-based indoor optical wireless networks. We propose a novel double-tier access point (AP) architecture based on an array of arrays of vertical cavity surface emitting lasers (VCSELs) to provide a seamless grid-of-beam coverage with multi-Gb/s per beam. We present systematic design and thorough analytical modeling of the AP architecture, which are then applied to downlink system modeling using non-imaging angle diversity receivers (ADRs). We propose static beam clustering with coordinated multi-beam joint transmission (CoMB-JT) for network interference management and devise various clustering strategies to address inter-beam interference (IBI) and inter-cluster interference (ICI). Non-orthogonal multiple access (NOMA) and orthogonal frequency division multiple access (OFDMA) schemes are also adopted to handle intra-cluster interference, and the resulting signal-to-interference-plus-noise ratio (SINR) and achievable data rate are derived. The network performance is studied in terms of spatial distributions and statistics of the downlink SINR and data rate through extensive computer simulations. The results demonstrate that data rates up to 15 Gb/s are achieved within the coverage area and a properly devised clustering strikes a balance between the sum rate and fairness depending on the number of users.},
note = {Version Number: 1},
keywords = {electronic engineering, FOS: Electrical engineering, information engineering, LRDC, Signal Processing (eess.SP)},
pubstate = {published},
tppubtype = {misc}
}
In this paper, we put forward a proof of concept for sixth generation (6G) Terabit infrared (IR) laser-based indoor optical wireless networks. We propose a novel double-tier access point (AP) architecture based on an array of arrays of vertical cavity surface emitting lasers (VCSELs) to provide a seamless grid-of-beam coverage with multi-Gb/s per beam. We present systematic design and thorough analytical modeling of the AP architecture, which are then applied to downlink system modeling using non-imaging angle diversity receivers (ADRs). We propose static beam clustering with coordinated multi-beam joint transmission (CoMB-JT) for network interference management and devise various clustering strategies to address inter-beam interference (IBI) and inter-cluster interference (ICI). Non-orthogonal multiple access (NOMA) and orthogonal frequency division multiple access (OFDMA) schemes are also adopted to handle intra-cluster interference, and the resulting signal-to-interference-plus-noise ratio (SINR) and achievable data rate are derived. The network performance is studied in terms of spatial distributions and statistics of the downlink SINR and data rate through extensive computer simulations. The results demonstrate that data rates up to 15 Gb/s are achieved within the coverage area and a properly devised clustering strikes a balance between the sum rate and fairness depending on the number of users.