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17 pages, 3632 KiB

Open AccessArticle

Wheel-Based MDM-PON System Incorporating OCDMA for Secure Network Resiliency

by Meet Kumari, Vivek Arya and Hamza Mohammed Ridha Al-Khafaji

Photonics 2023, 10(3), 329; https://doi.org/10.3390/photonics10030329 - 19 Mar 2023

Cited by 6 | Viewed by 1480

Wheel-based network resilience passive optical network (PON) based on mode division multiplexing (MDM) can be integrated with optical code division multiple access (OCDMA) schemes efficiently for the fixed and backhaul traffic under normal and break/failure fiber operating conditions. In this work, a bidirectional [...] Read more.

Wheel-based network resilience passive optical network (PON) based on mode division multiplexing (MDM) can be integrated with optical code division multiple access (OCDMA) schemes efficiently for the fixed and backhaul traffic under normal and break/failure fiber operating conditions. In this work, a bidirectional 10/2.5 Gbit/s hybrid MDM-OCDMA-PON system using multi-weight zero cross-correlation (MWZCC) code is proposed. Donut modes 0 and 1 are incorporated by the MDM technique in the proposed system. The benefit of this work is to offer an inexpensive, high-bandwidth and advanced long-haul network with satisfactory resource utilization ability for fiber links with protection against faults and to improve the reliability along with survivability of the network. The simulation results show the successful realization of the multimode fiber (MMF) link at 1.6 km in the uplink and 1.2 km in the downlink directions under an acceptable bit error rate (BER). The minimum accepted received power of −31 dBm in uplink and −27 dBm in downlink over 1 km link at 10/2.5 Gbit/s rate is obtained. Moreover, the minimum received power of −20 dBm in uplink and −30 dBm downlink is achieved by using MWZCC code compared to other codes handling 58 simultaneous end users. Further, the influence of fiber impairments and connected devices on the proposed approach is numerically evaluated. Moreover, it is shown that the wheel based proposed approach performs well than other topologies for the bidirectional network resilience transmission. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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14 pages, 21727 KiB

Open AccessArticle

Multi-User Visible Light Communication and Positioning System Based on Dual-Domain Multiplexing Scheme

by Zhongxu Liu and Changyuan Yu

Photonics 2023, 10(3), 306; https://doi.org/10.3390/photonics10030306 - 13 Mar 2023

Cited by 2 | Viewed by 1199

Abstract

Visible light communication and positioning (VLCP) is a promising candidate for constructing a multi-functional wireless network with large-scale connectivity and centimeter-level positioning. However, there is still a lack of effective methods to offer simultaneous visible light communication (VLC) and visible light positioning (VLP) [...] Read more.

Visible light communication and positioning (VLCP) is a promising candidate for constructing a multi-functional wireless network with large-scale connectivity and centimeter-level positioning. However, there is still a lack of effective methods to offer simultaneous visible light communication (VLC) and visible light positioning (VLP) functions for multiple users. Thus, we propose a multi-user VLCP system based on a dual-domain multiplexing (DDM) scheme, where both the time and code resources are multiplexed to transmit VLCP signals for multiple users simultaneously. In the proposed system, the data of different users are distinguished by using code division multiplexing technology, while the VLCP signals transmitted from different LEDs are separated by adopting time division multiplexing technology. The performances, including bit-error rate and positioning error, are evaluated through both simulation and experimentation to verify the feasibility of the proposed multi-user VLCP system. In the experiment, a VLCP system with four LED transmitters was able to simultaneously support low-speed VLC with free error and accurate VLP with a 2 cm precision for eight users. This offers an effective solution to support a large number of users with simultaneous VLC and VLP functions in the future multi-functional wireless network. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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13 pages, 57000 KiB

Open AccessCommunication

Spin-Orbit Coupling in Quasi-Monochromatic Beams

by Yuriy Egorov and Alexander Rubass

Photonics 2023, 10(3), 305; https://doi.org/10.3390/photonics10030305 - 13 Mar 2023

Cited by 5 | Viewed by 1025

Abstract

We investigate the concept that the value of the spin-orbit coupling is the energy efficiency of energy transfer between orthogonal components. The energy efficiency changes as the beam propagates through the crystal. For a fundamental Gaussian beam, its value cannot exceed 50%, while [...] Read more.

We investigate the concept that the value of the spin-orbit coupling is the energy efficiency of energy transfer between orthogonal components. The energy efficiency changes as the beam propagates through the crystal. For a fundamental Gaussian beam, its value cannot exceed 50%, while the energy efficiency for Hermite–Gaussian and Laguerre–Gaussian beams of higher orders of the complex argument can reach a value close to 100%. For Hermite–Gauss and Laguerre–Gauss beams of higher orders of real argument, the maximum energy efficiency can only slightly exceed 50%. It is shown that zero-order Bessel–Gauss beams are able to achieve an energy efficiency close to 100% when generating an axial vortex in the orthogonal component in both monochromatic and polychromatic light, while for a polychromatic Laguerre–Gauss or Hermite–Gauss beam of a complex argument, the energy efficiency reduced to a value not exceeding 50%. The spin angular momentum is compensated by changing the orbital angular momentum of the entire beam, which occurs as a result of the difference in the topological charge of the orthogonally polarized component by 2 units. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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17 pages, 15922 KiB

Open AccessArticle

Link-Blockage Model and AP-Placement Scheme for No-Blockage Link between AGV and AP in Logistics–Warehousing VLC Network

by Guiyu Gong, Chaoqin Gan, Yong Fang, Yifan Zhu and Qiuyue Hu

Photonics 2023, 10(1), 31; https://doi.org/10.3390/photonics10010031 - 27 Dec 2022

Viewed by 1112

Abstract

In this paper, the blockage problem of the optical link between AGV (autonomous ground vehicles) and AP (access point) in the logistics–warehousing VLC (visible light communication) network is analyzed. First, based on the random geometric model, a link-blockage model is proposed. Given the [...] Read more.

In this paper, the blockage problem of the optical link between AGV (autonomous ground vehicles) and AP (access point) in the logistics–warehousing VLC (visible light communication) network is analyzed. First, based on the random geometric model, a link-blockage model is proposed. Given the position of AGV, AP and obstacle, the blockage state of the VLC link between AGV and AP can be obtained through this model. Then, an AP-placement scheme based on the link-blockage model is proposed. Under this AP placement, AGVs in any position have a reliable link that is not affected by obstacles. During the movement of AGV, the VLC link of AGV will not be interrupted by a random blockage. Finally, the effectiveness of the link-blockage model is demonstrated by the shadow method. In this paper, the link outage probability and the data rate under different AP heights, AP spacings and the number of obstacles are simulated. Simulation results show that the VLC link can keep uninterrupted under the AP placement proposed in this paper. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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13 pages, 7865 KiB

Open AccessArticle

DNN-Based Physical-Layer Network Coding for Visible Light Communications

by Xuesong Wang, Runxin Zhang, Xinyan Xie and Lu Lu

Photonics 2023, 10(1), 23; https://doi.org/10.3390/photonics10010023 - 26 Dec 2022

Cited by 1 | Viewed by 1506

Abstract

The key difference between visible light communication (VLC) and radio frequency (RF) communication is the former’s line-of-sight (LOS) transmission nature, and hence a relay node has to be adopted for VLC to extend its coverage. Physical-layer network coding (PNC) has the advantage of [...] Read more.

The key difference between visible light communication (VLC) and radio frequency (RF) communication is the former’s line-of-sight (LOS) transmission nature, and hence a relay node has to be adopted for VLC to extend its coverage. Physical-layer network coding (PNC) has the advantage of doubling the throughput of a two-way relay network (TWRN), where two end nodes exchange information via the help of a relay, compared with the conventional store-and-forward routing strategy. Although PNC has been studied for VLC in the literature, the state-of-the-art schemes are highly inefficient, requiring tight phase synchronization between the two end nodes, and hence difficult to realize. This paper proposes the application of a deep neural network (DNN) to a PNC VLC system, named DP-VLC, that enables misaligned phases and can deal with the light channel gains and noises in a satisfactory manner without introducing additional computation complexities. We implement DP-VLC using the universal software radio peripheral (USRP) software radio platform and a self-developed VLC optical front-end using commercial off-the-shelf (COTS) light-emitting diodes (LEDs) and photo-diodes (PDs). We find that irregular constellations generated by DP-PNC can be transmitted and recovered in a 1.5 m VLC link effectively. Experimental results show that our DP-PNC prototype performs better than conventional PNC VLC system when the signal-interference-to-noise ratio (SINR) of received optical signals is larger than 13.63 dB and can achieve a throughput of up to 77.38 Mbps in a 20 MHz channel under PNC scheme when the SINR is 22.86 dB. More importantly, we find that DP-VLC performs even better than fixed-constellation PNC system in the saturated SINR regime (e.g., 20–25 dB) where non-linear effects may happen compared with moderate SINR regimes (e.g., 10–20 dB), showing its adaptability to unpredictable impairments in optical links. Our first attempt at realizing DNN-based optical PNC in a TWRN has paved the way for future PNC-enhanced VLC systems. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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12 pages, 5088 KiB

Open AccessArticle

Support Vector Machine-Based Soft Decision for Consecutive-Symbol-Expanded 4-Dimensional Constellation in Underwater Visible Light Communication System

by Wenqing Niu, Jifan Cai, Zhiteng Luo, Jianyang Shi and Nan Chi

Photonics 2022, 9(11), 804; https://doi.org/10.3390/photonics9110804 - 26 Oct 2022

Cited by 1 | Viewed by 1476

Abstract

Nowadays, underwater visible light communication (UVLC) has become one of the key technologies for high-speed underwater wireless communication. Because of the limited modulation bandwidth and nonlinearity of the optoelectronic devices in the UVLC system, the combination of inter-symbol interference and nonlinear impairment will [...] Read more.

Nowadays, underwater visible light communication (UVLC) has become one of the key technologies for high-speed underwater wireless communication. Because of the limited modulation bandwidth and nonlinearity of the optoelectronic devices in the UVLC system, the combination of inter-symbol interference and nonlinear impairment will inevitably degrade the transmission performance. Advanced digital signal processing methods including equalization and decoding are required. In the past few years, Support vector machine (SVM) has been widely investigated in quadrature amplitude modulation (QAM) for soft decision in the decoding process. However, previous works only consider 2-dimensional (2-D) separate symbol, ignoring the correlation between consecutive symbols. In this paper, we propose to use SVM for soft decision with a 4-dimensional (4-D) constellation by concatenating two consecutive symbols. To deal with the increasing computational complexity in the SVM training phase, bit-based binary SVM multi-class strategy and an edge-detection-based data pre-processing method are employed. In this paper, we demonstrate a carrierless amplitude and phase (CAP) 16-QAM UVLC system. Experimental results indicate that the performance is greatly improved when using consecutive-symbol-expanded 4-D constellation with SVM for soft decision. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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17 pages, 3749 KiB

Open AccessArticle

Cross-Domain Resource Allocation Scheme with Unified Control Architecture in Software Defined Optical Access Network

by Bowen Bao, Qiuyan Yao, Chao Li, Zhengjie Sun, Xiangyue Li, Wei Bai, Hui Yang, Sheng Liu and Yunbo Li

Photonics 2022, 9(10), 740; https://doi.org/10.3390/photonics9100740 - 08 Oct 2022

Cited by 1 | Viewed by 1385

Abstract

With the rapid development of communication and the rise of new network services, the resource provisioning of the optical access network becomes more significant than before, especially under the multiple-domain networking situation with the requirement of cross-domain service support. For the sake of [...] Read more.

With the rapid development of communication and the rise of new network services, the resource provisioning of the optical access network becomes more significant than before, especially under the multiple-domain networking situation with the requirement of cross-domain service support. For the sake of high resource utilization to establish more connections of services, this paper proposes a cross-domain resource allocation (CDRA) scheme in a software-defined optical access network to meet the huge bandwidth supporting the requirement of new network services. To achieve this purpose, the global evaluation strategy with the consideration of the traffic situation in each node in its domain is presented in the CDRA scheme, and its interaction process makes decisions for comprehensive optimal resource allocation by integrating radio resources and optical aggregation resources of the entire access network. Furthermore, to manage the resources among multiple domains and support the interaction process of the CDRA scheme, a cross-domain unified control architecture is firstly upgraded by using software-defined networking technology, which includes the further design of CDRA function modules with the global evaluation strategy. The simulation results verify the feasibility of the upgraded architecture and further show that the proposed CDRA scheme can effectively decrease the blocking probability with a 29.35% improvement, balance the network load, and enhance the utilization of network resources of the network. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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13 pages, 1663 KiB

Open AccessArticle

Partial-Failure Segregated Spectrum Assignment for Multicast Traffic in Flex-Grid Optical Networks

by Yang Qiu

Photonics 2022, 9(7), 488; https://doi.org/10.3390/photonics9070488 - 12 Jul 2022

Viewed by 1178

Abstract

In this paper, we propose a new algorithm called the partial-failure segregated multicasting routing and spectrum assignment (PFS MRSA) algorithm to improve the service blocking performance of the multicast transmission in flex-grid optical networks (FGONs). By segregating one failure destination leaf-node from a [...] Read more.

In this paper, we propose a new algorithm called the partial-failure segregated multicasting routing and spectrum assignment (PFS MRSA) algorithm to improve the service blocking performance of the multicast transmission in flex-grid optical networks (FGONs). By segregating one failure destination leaf-node from a blocked multicast request and accommodating the failure destination leaf-node and the remaining multicast request independently, the success probability of accommodating the originally blocked multicast request can be greatly increased. In this way, the proposed PFS MRSA algorithm can effectively reduce the service blocking probability for the multicast services in FGONs. Simulation results show that the proposed PFS MRSA algorithm achieves significant reduction in service blocking probability when compared with the conventional MRSA algorithms, and such reduction can even reach 100% in some scenarios with low traffic load. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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Review

Jump to: Research

24 pages, 24727 KiB

Open AccessReview

Photonic Integrated Circuits for Passive Optical Networks: Outlook and Case Study of Integrated Quasi-Coherent Receiver

by Francisco Rodrigues, Carla Rodrigues, João Santos, Cláudio Rodrigues and António Teixeira

Photonics 2023, 10(2), 182; https://doi.org/10.3390/photonics10020182 - 08 Feb 2023

Cited by 1 | Viewed by 3139

Abstract

Photonic Integrated Circuits (PICs) are taking a major role in the telecommunications and datacenter markets. The increased complexity of coexisting and fast evolving standards for Passive Optical Networks (PONs) suggests the introduction of PICs will be the next step in PON related optoelectronics. [...] Read more.

Photonic Integrated Circuits (PICs) are taking a major role in the telecommunications and datacenter markets. The increased complexity of coexisting and fast evolving standards for Passive Optical Networks (PONs) suggests the introduction of PICs will be the next step in PON related optoelectronics. The PICs ecosystem has greatly matured in the past years, becoming a solution that can cope with the requirements of industry and academia, and presenting the flexibility of combining multiple platforms available towards viable commercial solutions. In this review, the evolution of PONs and PICs is presented, with a focus on the optoelectronic integration of PICs for PONs and coherent PONs. To demonstrate the potential of PICs and their combination with electronics, a quasi-coherent receiver based on co-hosted PIC and Application Specific Integrated Circuit (ASIC) is presented and characterized. Full article

(This article belongs to the Special Issue Advances in Optical Communication and Network)

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