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MEMS-based Free Space Optical Networks

Atakora, Michael O.
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1640077509247131

Abstract Details

2022, Doctor of Philosophy (PhD), Ohio University, Electrical Engineering & Computer Science (Engineering and Technology).
Integrating highly directional optical radios into next generation wireless systems is increasingly gaining traction due to the potential benefits to be derived from the several terahertz (THz) of spatially reusable spectrum available. In this dissertation, we explore three main research problems within the domain of laser-based free space optical networks and which fall under the broader areas of optimal multicast, neighbor discovery and link quality indication. For the optimal multicast problem, we show that the static version of this problem is an abstraction of the minimum weight set cover problem which is known to be NP-hard. A computationally cheap greedy local optimum heuristic is then proposed which has a time complexity of O(N) compared to the O(N^2) time complexity of the well known O(log N) approximation algorithm to the set cover problem. We then proceed to the version of the optimal multicast problem in mobile scenarios, and show that it is an abstraction of the time dependent prize collecting traveling salesman problem which is NP-hard. In formulating our problem, we develop a novel prize assignment strategy that guarantees the selection of mutually disjoint multicast sets. Due to the problem being NP-hard, we provide several potential heuristics for multicast in mobile scenarios. We evaluate the performance of these multicast algorithms in delay tolerant networking conditions, and in a typical 5G backhaul network. For the multicast problem, we assumed that nodes knew the transceiver orientations of recipients via the dissemination of coordinates obtained via the global positioning system (GPS) over a low rate omnidirectional radio frequency (RF) channel. However, in delay averse and high throughput self configuring networks, nodes might not possess GPS capabilities. In addition, they might not have a control channel. Agile neighbor discovery in such situations is then of critical importance. Given an optical wireless network with MicroElectroMechanical Systems (MEMS)-based receivers, we explore the use of adaptive combinatorial group testing and contour tracing to achieve extremely fast neighbor discovery latencies. We cast the neighbor discovery problem as a combinatorial group testing problem to which we propose the use of adaptive hierarchical boolean combinatorial group testing algorithms that are practical and efficient. Compared to Raster and Lissajous pattern-based scanning, we report 99.92% and 87% reduction in latency, respectively, for an array of 10^6 micromirrors (approximately XGA resolution). We then proceed to develop a pattern based algorithm which leverages on both group testing and contour tracing to significantly reduce discovery latencies. Compared to hierarchical group testing algorithms and the Moore-neighbor contour tracing algorithm, we report 63.4% and 4.91% reduction in latency, respectively, for an array of 10^6 micromirrors. Finally, we explore link quality indication for network topology control in MEMS based FSO networks. In the area of optical link quality indication, our proposed metric effectively encapsulates possible channel impairment sources such as atmospheric attenuation, scintillation induced fading and misalignment in a single metric.
Harsha Chenji (Advisor)
218 p.
Computer Engineering; Computer Science; Electrical Engineering
free space optics; FSO; neighbor discovery; multicast; MEMS; link quality indication

Recommended Citations

Citations

  • Atakora, M. O. (2022). MEMS-based Free Space Optical Networks [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1640077509247131

    APA Style (7th edition)

  • Atakora, Michael. MEMS-based Free Space Optical Networks. 2022. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1640077509247131.

    MLA Style (8th edition)

  • Atakora, Michael. "MEMS-based Free Space Optical Networks." Doctoral dissertation, Ohio University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1640077509247131

    Chicago Manual of Style (17th edition)

ohiou1640077509247131
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This open access ETD is published by Ohio University and OhioLINK.