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The sharply growing demand for increased transmission capacity and bandwidth in last meter and last mile access networks together with the commercialization of fifth generation (5G) wireless systems has been opening up new opportunities for non-radio frequency (RF)-based wireless technologies. Visible light communications (VLC) technology is a potential candidate for access networking in 5G, which offers a higher spectral efficiency than RF-based Femtocell networks by three orders of magnitude. This paper proposes an all wireless optical bidirectional VLC multiple access scheme for pure VLC network access points in terminals. Centralized coordination is adopted to reduce the system complexity. And reservation of resource is introduced to guarantee collision avoidance during data frame transmission. The proposed multiple access scheme introduces special system parameters to achieve the balance of system throughput and access latency. The feasibility of the proposed scheme is verified by both theoretical analysis and experimental investigation. We show that the proposed scheme is suitable for a bidirectional pure VLC access network and can be used as a supplement in the IEEE 802.11 bb for 5G+bidirectional VLC application scenarios.

We propose an analog pre-distortion waveform shaping scheme based on a high-speed VLC scheme, which generates a non-return-to-zero switch keying (NRZ-OOK) modulated signal shaped by a pre-distortion waveform shaping module through a field-programmable gate array (FPGA) and emitted from the transmitter. Experimental results show that this simple system can fully preserve frequency components, extend system bandwidth up to 250Mhz, and improve the system performance at a communication distance of 3m and LED power of 0.02W.

We propose an adaptive seamless vertical handover scheme for hybrid visible light communication-infrared (VLC-IR) networks in ship cabins based on Sarsa-lambda reinforcement learning algorithm. Compared with the Q-learning and Sarsa, the proposed algorithm surpasses the average downlink data rate by 13% and 14%, respectively. Moreover, the proposed algorithm outperforms the average downlink data rate of immediate handover and dwell handover schemes by 57% and 22%, respectively when the user device movement speed is 1 m/s.

We propose an artificial neural network-embedded visible light positioning (VLP) scheme based on a conventional monitoring system in which the transmitter and receiver comprise a single illuminating LED and two standard surveillance cameras, respectively. Experimental results show that this simple system achieved millimeter-level positioning accuracy and exhibited good antitilt ability and robustness. The VLP system achieved high-precision three-dimensional positioning with a mean positioning error (MPE) of 0.76 cm, even if the object was inclined at different angles. Moreover, the MPEs of the single-light system were only 0.65 and 0.67 cm when the tilt angle was 15 deg and −15 deg, respectively. This scheme is a low-cost solution for accurate positioning that could be applied in marine vessel operations, mining operations, shopping center, supermarket, factories, and warehouses where monitoring systems presently exist.

Key elements in developing a successful universal college student transit pass program (U-Pass program) are investigated from the perspectives of three involved parties of interest: transit agencies, university administrations, and students. By collecting information from online surveys, case examples, literature, and other useful online resources, a generalized procedure of a U-Pass program is proposed, broken down into three phases: planning, launching, and implementation. In each phase, key elements and actions that lead to successful programs are investigated from the perspectives of the three involved parties. The roles of the three parties as well as how they interact with each other are also examined. Furthermore, some of the underlying factors that lead to program success are explored in the context of different built environment settings. As a benchmark study, this paper extends work from a Transit Cooperative Research Program synthesis to gain insight into how U-Pass programs have been planned, launched, and implemented. The research findings could assist responsible transit agencies and educational institutions in enhancing their current U-Pass programs or launching new programs in the future.

A degenerated MAC layer feedback-repeat reliable transmission scheme was proposed and experimentally demonstrated for LiFi networking with B5G/6G. The experimental results of end-to-end packet loss ratio precedes 1/10000 (equals to 99.999% reliability).

An experiment-data-driven channel-modeling method based on bidirectional long short-term memory is proposed for visible light communication channels. The resulting mean absolute error is stable in a small range, reaching 0.009 without occupying spectrum resources.

Experimental demonstration of a practical multiple access scheme for VLC networking with both optical downlink and uplink. System normalized throughput and user access delay were measured to be feasible for bidirectional VLC networking applications scenario.

In this paper, an artificial neural network (ANN) based high-precision positioning system using triple-LED and security camera is proposed, which achieves a mean positioning error (MPE) of 0.87 cm in a space of 1 m x 1 m x 1 m.

This paper proposes a reinforcement-learning-based resource allocation algorithm in multi-model optical networks, which is designed based on n-dimensional matrix diagram. Simulation results show that the proposed algorithm can efficiently optimize resource allocation.

We experimentally demonstrated a 180 Mbps real-time visible light communication link with a low-cost and low-complexity adder-circuit-based feed forward equalizer with achieved extremely low bit error rate at 2.8710-6 over 2.3 m transmission distance.

Adverse weather has been recognized as an important factor to affect travelers’ activity plans in departure time, transport mode, route taken, or cancellation. In the storm, road waterlogging degrades the capacity of road networks and the service quality of transit systems, which further may affect the supply and demand for transit. Based on a typical case in Shanghai that commuters have no easy access to metro service, this paper aims to explore how transit passengers adapt to different situations in the storm and what emergency plans should be taken accordingly. Derived from the revealed preference (RP) and stated preference (SP) survey results for experienced transit commuters, a nested logit (NL) model was developed to describe the travel behavior of transit commuters. Six alternatives, Direct Bus, Bus + Bus, Metro, Bus + Metro, Taxi, and Cancel Trip, and three storm scenarios were set for transit commuters in this case. Estimated parameters indicate that, in storm weather, crowdedness is less considered by transit commuters, and transfer times, walking time, in-vehicle time, and waiting time have negative effects on the selection of the corresponding alternative, whereas the impact of taxi fare is positive since the higher fare is usually accompanied by worse weather and traffic condition. Sensitivity analysis shows that walking time to metro station, in-vehicle time, and waiting time at a bus stop are the most critical factors leading to transit ridership reduction in the storm. According to this, three possible plans for the transit operator, shuttle bus to the metro station (P1), information announcement (P2), and route adjustment (P3), are simulated and compared. We recommend adopting P2, P2 + P3, and P1 + P2 + P3 in turn with the increase of road waterlogging. These findings have important practical implications for developing transit emergency management plans and serve as references for the transit agencies and operators.

We demonstrated an outdoor 70 m duplex portable visible-light-communication (VLC) system. Reliable communications above 8 Mbps is achieved using joint scrambler and filter scheme under the effect of solar irradiance with a bit-error-rate of 3.2×10-6.

In this paper, we report on a non-directed line-of-sight (ND-LOS) visible light communication (VLC) system using an automated rotating photodetector array receiver with a wide field-of-view, which is more flexible in practical applications. The geometry of ND-LOS propagation model is numerically analyzed using Monte Carlo method. We experimentally demonstrate a 180 Mbps real-time on-off keying ND-LOS VLC link with a bit error rate of less than 2.87 ×10−6 over a transmission distance of 2.3 m, which employs a single white phosphorous light-emitting diode with a transmit power of 1 W.

Ultraviolet is a vital spectrum in wireless optical communication. There are a lot of studies have been done in wireless ultraviolet communication. However, Ultraviolet communication networking mainly focuses on self-organizing networks and multi-hop networks. We proposed a new multi-access scheme of star topology network for confidential communications in semi-open spaces on the surface of ships. We verified the feasibility of the scheme through theoretical analysis and system simulation. It is proved that the scheme is suitable for ultraviolet communication and has better performance in a multi-user network. This scheme could be a sub-scheme for the next generation communication network combined with ultraviolet light communication.

In this paper, a topology discovery mechanism for Visible Light Communication (VLC) networking is proposed, which is essential to the control and management of the LiFi networks. In our mechanism, the Access Points (APs) in the LiFi network respond to the changes of network topology. The terminals collect their topology-related information, and then deliver the information to the APs during their transmission opportunities. The APs regularly update the topology information and upload the information to the Internet in time. A VLC networking system is designed and examined by the experimental results of the simulation mechanism in static and dynamic scenarios.

We propose a Visible light positioning (VLP) system which can satisfy the requirements in the places where monitors are required to grasp the location of multiple people or vehicles, such as unmanned supermarkets, warehouses, factories, and other large buildings with safety issues. Which means when the security cameras capturing images, the coordinates of the objects can be obtained and displayed at the same time. This novel Multiple Input Multiple Output (MIMO) VLP system which can monitor multiple objects at the same time provides accurate and high-speed multiple objects indoor positioning based on the Space Division Multiple (SDM), Wavelength Division Multiplexing (WDM) and the under-sampled phase shift ON-OFF keying (UPSOOK). The experimental results show that the proposed system achieves accuracy of 10cm with the range of tilting angle degree is 0° to 45°. The result means the system does well in robustness and accuracy.

A digital predistortion waveform shaping scheme combined with a blue filter is proposed to optimize both the rise and fall times of a light-emitting diode (LED) and the optical receiver current of the signal of the real-time visible light communication (VLC) system. The proposed scheme is implemented on a field-programmable gate array (FPGA) and a digital-to-analog converter based test bed, which is flexible and reconfigurable by programming the FPGA to match different LED characteristics and varied data rates. A 262-Mb/s non-return-to-zero on-off keying modulation based real-time VLC link with a bit error rate of less than 1.0 × 10-6 is achieved over a transmission distance of 5.0 m, which uses a single white phosphorous LED with a limited power of 0.1 W.

A support vector machine (SVM)-based data detection for 8-superposed pulse amplitude modulation and direct-current-biased optical orthogonal frequency division multiplexing in visible light communication is proposed and experimentally demonstrated. In this work, the SVM detector contains multiple binary classifiers with different classification strategies. The separating hyperplane of each SVM is constructed by means of the training data. The experiment results presented that the SVM detection offers improved bit error rate performance compared with the traditional direct decision method.

With the rapid growth of global network traffic, more and more high-capacity network services are required. Traditional wavelength division multiplexing (WDM) networks are inadequate in terms of service scheduling and network management, so optical transport networks (OTN) have been proposed. OTN offers electric-layer switching ability to support finer granularity and higher spectrum efficiency. In OTN, we need to realize routing, modulation, wavelength, and port assignment (RMWPA) for supporting optical-electric (O/E) conversion (i.e., O/E port). Efficient RMWPA will significantly reduce the cost of operators. In this paper, we explore multi-modal information from OTN, and image the topology and routes to capture the information of the OTN and services. We design a cost-efficient RMWPA (CE-RMWPA) algorithm based on reinforcement learning to realize RMWPA for reducing cost in OTN. The proposed algorithm can interact with the OTN environment and learn how to make improved decisions based on the environment’s feedback. Simulative results demonstrate that the CE-RMWPA algorithm can achieve the optimization of RMWPA for reducing cost.

Introduction Mobility limitation can hinder one's access to goods and services that may lead to poor health outcomes, especially among older adults who do not drive. Existing literature on older adults' mobility limitations has majorly focused on single transportation mode (e.g., walking, public transit), and little is known about the differences in trip purposes and all-mode transportation patterns between driving older adults and non-driving counterparts especially in suburban and rural areas with more aging population. Methods 502 individuals aged 65 and older were included in our study drawn from a transportation survey conducted in Washington County, Wisconsin. Binary and ordered logistic regression analyses were conducted to determine whether older adults’ driving status was significantly associated with their trip purposes and trip frequency by various modes, while controlling for covariates including socio-demographic characteristics. Results A larger percentage of non-driving older adults compared to driving counterparts needed to make maintenance trips (e.g., medical or dental appointments, food pantry) but a smaller percentage for leisure trips (e.g., socializing, movies/art/theater). However, there was no difference in subsistence trips (e.g., worship, work) between drivers and non-drivers. While making more trips via dependent modes (e.g., riding with family or friends, public transit), non-driving older adults traveled less frequently than older drivers overall, because they made fewer trips via independent modes (e.g., driving, walking). Conclusions The findings indicate that non-driving older adults are in greater need for medical care or food assistance, as well as having greater limitations in mobility and dependency on others for trips. In addition, further analyses in this study suggest improvement of alternative transportation services (e.g., advanced vehicle scheduling methods, inter-county transit service collaboration), usage of assistive technology, and education about transportation services to help improve mobility among non-driving older adults in suburban and rural areas.