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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>On the performance of a UAV-based Malaga-distributed FSO/FSO communication system with NOMA</title>
      <link>https://trid.trb.org/View/2549328</link>
      <description><![CDATA[Non-Orthogonal Multiple Access (NOMA) is an efficient communication technique that can offer improved spectral efficiency, ultra-low latency and massive connectivity and its integration with Free Space Optical (FSO) communication can improve the network capacity to a great extent. In this manuscript, an Unmanned Aerial Vehicle (UAV) is employed as a relay in an FSO/FSO downlink network, comprising of two users, user 1, U1 and user 2, U2, using Amplify-and-Forward (AF) protocol. UAVs can prove to be assets in disaster-struck situations (during natural disasters such as earthquakes, floods, etc.), when all terrestrial communication is at halt. The performance of this system is determined in the presence of atmospheric attenuation, Malaga (ℳ) turbulence fading, pointing errors and Angle-of-Arrival (AoA) fluctuations. Heterodyne detection (HD) technique is used for information detection at the users for providing improved sensitivity and Signal-to-Noise Ratio (SNR). The closed-form expressions for Outage Probability (OP), Ergodic Capacity and Bit Error Rate (BER) are derived in terms of Meijer-G function and OP is analyzed with respect to different weather conditions, turbulence levels, pointing error coefficients, NOMA coefficients and Field-of-View (FoV) angles. It is observed that at an SNR of 0 dB, the outage at U1 and U2 is 0.5489 and 0.7423, respectively. A comparison of OP is presented for the cases of HD and Intensity Modulation/Direct Detection (IM/DD) techniques and for NOMA and Orthogonal Multiple Access (OMA) technologies. Ergodic Capacity is analyzed for different turbulence strengths and pointing error values and it can be noticed that it is enhanced by reducing the turbulence strength and pointing error impairment. BER is observed for different modulation schemes and it is found to be 7.7×10−3, 1.9×10−2, 7.9×10−2 and 2.8×10−2, for QPSK, 8-PSK, 16-PSK and 16-QAM, respectively, at an SNR of 30 dB. In addition, BER is analyzed for clear, rainy and foggy weather along with different pointing errors and turbulence regimes. Monte-Carlo simulations are also carried out in order to validate the correctness of the obtained analytical results.]]></description>
      <pubDate>Thu, 29 May 2025 09:22:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2549328</guid>
    </item>
    <item>
      <title>Modelling, Optimisation and Evaluation of Multi-Transmitters FSO Link for Ground to Train Communication</title>
      <link>https://trid.trb.org/View/2526920</link>
      <description><![CDATA[This paper investigates the potential of Free Space Optical (FSO) communication technology for high-speed train (HST) systems by developing mathematical models for G2T-FSO (Ground to Train) communication links across single, curved, and double-curved tracks. The key contribution of this research is the introduction of novel G2T-FSO models, incorporating multiple transmitters (single, double, triple, and quad) and considering different weather conditions (clear, rain, and fog) using NRZ-OOK modulation. The models were evaluated based on key performance metrics, including received power, signal-to-noise ratio (SNR), bit error rate (BER), and eye diagrams. Simulation results reveal that single and dual transmitter links are significantly impacted by geometrical and atmospheric losses, while triple and quad transmitters provide error-free G2T-FSO links with a BER of 10⁻⁹. Under clear weather conditions, communication ranges of up to 680 meters for straight tracks and 618 meters for curved tracks were achieved. These findings highlight that G2T-FSO links deliver superior performance compared to traditional HST communication technologies, offering enhanced range, reliability, and data capacity for high-speed, secure train communication systems.]]></description>
      <pubDate>Fri, 28 Mar 2025 09:12:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2526920</guid>
    </item>
    <item>
      <title>Next Generation Based Vehicular Visible Light Communications: A Novel Transmission Scheme</title>
      <link>https://trid.trb.org/View/2506211</link>
      <description><![CDATA[In this work, to tackle the line-of-sight (LoS) blockage constraint, a new transmission scheme for vehicle-to-vehicle (V2V) visible light communications (VLC) employing optical reflecting intelligent surfaces (RISs) is proposed and analyzed. To this end, the idea is to address the critical V2V-VLC LoS blockage impact concerning mobility scenarios. Moreover, multiple light-emitting diodes (LEDs)/transmitters-based headlights are employed to enhance the transmission propagation paths. Consequently, it significantly improves the overall reliability of the proposed RIS-aided V2V-VLC model. Further, to emphasize the reliability of the proposed V2V-VLC model, comprehensive path loss and energy efficiency modeling are accentuated. For the realistic V2V-VLC findings, modeling of the path loss corresponding to the intermediate communication links, i.e., between transmitter-RIS and RIS-receiver is emphasized. A novel closed-form expression of a lower bound for the required number of RIS elements to attain a targeted energy efficiency is also developed. Further, to mark interesting research insights, the performance of the proposed RIS-aided V2V-VLC scheme is also compared with the existing scheme. Furthermore, considering the key findings, it is observed that the proposed RIS-aided V2V-VLC scheme offers reliable communication despite mobility-concerned blockage. Moreover, the proposed scheme significantly outperforms the existing scheme concerning the targeted energy efficiency for the reasonable number of required RIS reflection elements.]]></description>
      <pubDate>Tue, 18 Feb 2025 10:43:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2506211</guid>
    </item>
    <item>
      <title>Free-Space Optical (FSO) Satellite Networks Performance Analysis: Transmission Power, Latency, and Outage Probability</title>
      <link>https://trid.trb.org/View/2384824</link>
      <description><![CDATA[In free-space optical satellite networks (FSOSNs), satellites can have different laser inter-satellite link (LISL) ranges for connectivity. As the LISL range increases, the number of satellites from among all the satellites in the constellation that will be needed on the shortest path between a source and a destination ground station decrease, and thereby the number of the LISLs on the shortest path decreases. Greater LISL ranges can reduce network latency of the path but can also result in an increase in transmission power for satellites on the path. Consequently, this tradeoff between satellite transmission power and network latency should be investigated, and in this work the authors examine it in FSOSNs drawing on the Starlink Phase 1 Version 3 (i.e., the latest version of Starlink's Phase 1) and Kuiper Shell 2 (i.e., Kuiper's biggest shell) constellations for different LISL ranges and different inter-continental connections. The authors use appropriate system models for calculating the average satellite transmission power (i.e., the average of the transmission power of all satellites on the shortest path) and network latency (i.e., the end-to-end latency of the shortest path). The results show that the mean network latency (i.e., the mean of network latency over all time slots) decreases and mean average satellite transmission power (i.e., the mean of average satellite transmission power over all time slots) increases with an increase in LISL range. For the Toronto–Sydney inter-continental connection in an FSOSN with Starlink's Phase 1 Version 3 constellation, when the LISL range is approximately 2,900 km, the mean network latency and mean average satellite transmission power intersect are approximately 135 ms and 380 mW, respectively. For an FSOSN with the Kuiper Shell 2 constellation in this inter-continental connection, this LISL range is around 3,800 km, and the two parameters are approximately 120 ms and 700 mW, respectively. For the Toronto–Istanbul and Toronto–London inter-continental connections, the LISL ranges at the intersection are different and vary from 2,600 km to 3,400 km. Furthermore, the authors analyze outage probability performance of optical uplink/downlink due to atmosphere attenuation and turbulence.]]></description>
      <pubDate>Sun, 30 Jun 2024 16:02:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/2384824</guid>
    </item>
    <item>
      <title>Ship Collision Avoidance Navigation Signal Recognition via Vision Sensing and Machine Forecasting</title>
      <link>https://trid.trb.org/View/2306953</link>
      <description><![CDATA[Ship collision avoidance (SCA) is an important technique in the field of decision-making in marine navigation. Although some promising solutions have been developed recently, there is still the lack of low-cost and reliable sensing equipment. Inspired by the low-cost of camera sensors and the success of machine learning, this paper designs a vision-based method to recognize ships and their micro-features for SCA navigation planning. Firstly, the authors develop a vision-based bearing, distance and velocity model based on a wide-field optical imaging system. Secondly, optical information is used to construct the micro-characteristic imaging model of ship navigation signals. Thirdly, they have solved the problem between a large field-of-view (FOV) and high-resolution imaging in vision-based marine navigation. Finally, an improved Adaboost algorithm is designed for the intelligent recognition of an open-sea target (ship types and light patterns). The proposed method has been verified by extensive experiments in a practical environment, and the results show that it can effectively and efficiently identify the navigation signal of a target ship.]]></description>
      <pubDate>Thu, 22 Feb 2024 11:48:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2306953</guid>
    </item>
    <item>
      <title>Performance analysis of AUV-carried RISs-aided multihop UWOC convergent with RF MRC systems over WGG oceanic turbulence</title>
      <link>https://trid.trb.org/View/2320701</link>
      <description><![CDATA[To establish reliable connection between Internet of Underwater Things (IoUT) devices and terrestrial data centers, this work first proposes a reconfigurable intelligent surface (RIS) aided multihop underwater wireless optical communication (UWOC) convergent with radio frequency (RF) uplink system. Specifically, the RIS carried by an autonomous underwater vehicle (AUV) is introduced into UWOC link to relax the line-of-sight (LOS) requirement and the maximal-ratio combining (MRC) receiver is adopted at the terrestrial data center to mitigate the RF link fading. It is assumed that the underwater thermocline channel is subject to the newly proposed Weibull-generalized gamma (WGG) turbulence distribution and the RF link composite fading follows Fisher-Snedecor F distribution. Additionally, the optical link misalignment is characterized by the zero-boresight pointing errors model. With the decode-and-forward (DF) relaying scheme, the analytical closed-form expressions of the outage probability (OP) and average bit error rate (ABER) of this system are mathematically achieved, and then the impacts of air bubbles, thermohaline gradient, the number of RIS elements, pointing errors, system structure, and the number of receive antennas are further investigated. Meanwhile, the analytical results are verified by Monte Carlo (MC) simulations. Results reveal that this hybrid system performance would degrade with the increased air bubble levels and thermohaline gradients. Notably, RIS can effectively alleviate the impact of underwater turbulence and this effect would be more pronounced as the number of RIS elements increases. This work will benefit the design and research of hybrid UWOC-RF system.]]></description>
      <pubDate>Wed, 24 Jan 2024 09:55:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2320701</guid>
    </item>
    <item>
      <title>Simulation Studies of Link Group in Elastic Optical Networks Used in Internet of Things Solutions</title>
      <link>https://trid.trb.org/View/2255797</link>
      <description><![CDATA[The elastic optical network (EON) solution is the most flexible in terms of allocation of resources for various traffic streams transported in core part (edge-cloud) of Internet of Things (IoT) networks. This paper presents the results of a study on the determination of the occupancy distribution and the loss probability for particular traffic flows offered in EONs supporting IoT systems. The purpose of the research was to determine the impact of: the number of links making up a group, the numbers of frequency slot units (FSUs) in individual EON link, the traffic intensity of individual traffic flows, the capacity of the EON link (number of FSUs) and the number of FSUs requested by different traffic streams. The developed simulation program of link group of EON allows the calculation of the values of the occupancy distribution and loss probability. The results obtained from the simulation are presented on the graphs in the form of points with confidence intervals.]]></description>
      <pubDate>Fri, 29 Sep 2023 10:47:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/2255797</guid>
    </item>
    <item>
      <title>Optical Camera Communication in Vehicular Applications: A Review</title>
      <link>https://trid.trb.org/View/1993864</link>
      <description><![CDATA[Recently, substantial development is observed in the area of Internet of Vehicles owing to the application of wireless communication technologies. Majority of these technologies are based on radio frequency (RF); however, RF spectra are overly congested and regulated, and hence, insufficient to support massive data traffic in the future. In recent times, optical camera communication (OCC) that uses a light-emitting diode (LED) as a transmitter and a camera as a receiver has been deemed an excellent solution for future intelligent transportation systems. As a communication medium, OCC mostly uses visible light, the spectrum of which is vast, completely free, and unregulated. The current outdoor environment is heavily crammed with LED infrastructures, and most vehicles have built-in cameras, rendering OCC immensely promising. OCC is highly secured, supports mobility, and can achieve an excellent bit-error rate. However, the data rate obtained using OCC is not as high as that obtained using other RF-based systems; therefore, its reliability in fast-changing channels is still under research. This review article discusses the applications of the OCC system in vehicle-to-vehicle and vehicle-to-infrastructure (or vice versa) networks; to the best of the authors' knowledge, this is the first extensive review dedicated to the above topic. Herein, the authors provide a general overview of OCC standardization in IEEE and ISO in recent years. Then, the authors explain the general principles of OCC, including channel characteristics, region of interest signaling, and modulation schemes particularly considered in vehicular communications. Additionally, the authors present a comprehensive overview of the effects of mobility, noise, and interference in OCC. Finally, the challenges and future opportunities in OCC are outlined.]]></description>
      <pubDate>Mon, 29 Aug 2022 15:52:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1993864</guid>
    </item>
    <item>
      <title>Orientation of a diffuse reflector for improved coverage in ID-FSOC for vehicular communications</title>
      <link>https://trid.trb.org/View/1982117</link>
      <description><![CDATA[Even with no line-of-sight (LoS), stations can optically communicate using Indirect line-of-sight diffused-light free-space optical communications (ID-FSOC). A diffuse reflector in the LoS of the stations reflects diffused light to them. But despite having diffused reflections in almost all directions, the orientation of a flat diffuse reflector defines the communications coverage. Therefore, there is a need for a tool that describes the relationship between the orientation of the diffuse reflector, the coverage, and the achievable data rates for the effective deployment of ID-FSOC. In this paper, the authors propose a model of the coverage of a diffuse reflector that can allow us to estimate the achievable data rates as a product of the orientation of the diffuse reflector. They use ground-to-vehicle communications as a demanding example scenario. They also propose RISE, a heuristic algorithm that optimizes the horizontal and vertical tilt angles of the reflector to maximize the achievable data rates. They show that 50% or more of the transmitted power of light is reflected, thereby achieving 1 Gbps or higher data rates across the optical local area network.]]></description>
      <pubDate>Wed, 24 Aug 2022 15:02:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1982117</guid>
    </item>
    <item>
      <title>High-Speed 3D Optical Sensing and Information Processing for Automotive Industry</title>
      <link>https://trid.trb.org/View/1847575</link>
      <description><![CDATA[This paper explains the basic principles behind two platform technologies that my research team has developed in the field of optical metrology and optical information processing: 1) high-speed 3D optical sensing; and 2) real-time 3D video compression and streaming. This paper will discuss how such platform technologies could benefit the automotive industry including in-situ quality control for additive manufacturing and autonomous vehicle systems. We will also discuss some of other applications that we have been working on such as crime scene capture in forensics.]]></description>
      <pubDate>Tue, 26 Oct 2021 14:30:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1847575</guid>
    </item>
    <item>
      <title>Analysis and Experimental Investigation of the Light Dimming Effect on Automotive Visible Light Communications Performances</title>
      <link>https://trid.trb.org/View/1867162</link>
      <description><![CDATA[The use of Visible Light Communications (VLC) in vehicular applications has become a major research area due to its simplicity, high performance to cost ratio, and great deployment potential. In this context, this article provides one of the very few analyses and experimental evaluations concerning the integration of a light dimming function in vehicular VLC systems. For this purpose, a vehicle-to-vehicle VLC prototype has been implemented and used to evaluate the systems’ communication performances in light dimming conditions, while decreasing the duty cycle from 40% to 1%, and increasing the communication range from 1 to 40–50 m. The experimental results showed that in normal lighting conditions, the VLC technology can easily support low duty cycle light dimming for ranges up to 40 m, while maintaining a 10-6 BER. Nevertheless, in strong optical noise conditions, when the system reaches its SNR limit, the communication range can decrease by half, whereas the BER can increase by 2–4 orders of magnitude. This article provides consistent evidence concerning the high potential of the VLC technology to support inter-vehicle communication links, even in light dimming conditions.]]></description>
      <pubDate>Tue, 27 Jul 2021 15:59:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1867162</guid>
    </item>
    <item>
      <title>See-Through a Vehicle: Augmenting Road Safety Information Using Visual Perception and Camera Communication in Vehicles</title>
      <link>https://trid.trb.org/View/1852223</link>
      <description><![CDATA[In this paper, the authors present the design, implementation and evaluation of non-line-of-sight (NLOS) perception to achieve a virtual see-through functionality for road vehicles. In this system, a safety event, such as pedestrian crossing or traffic list status or vehicle merge, that are occluded to a driver due to another vehicle on the driving lane, are perceived and communicated by the occluding vehicle. Each vehicle is equipped with a camera, placed on the dashboard, that perceives the scene in a drivers view. This scene is analyzed and mapped into specific warning codes that are specific to a safety event, and communicated as short packets using visible light communication. The camera in the following vehicle captures this information and generates a recommendation for safety action to the driver by comparing the warning from the packet and from its own scene perception. Through experimental evaluations of a proof-of-concept implementation, the authors show that their system is able to achieve up to 90% accuracy in identifying nine occluded safety events, which correspond to traffic light statuses (red, green, yellow), other vehicles’ lane change behaviors (merge/leave lane left/right), and pedestrian detection.]]></description>
      <pubDate>Tue, 25 May 2021 16:21:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1852223</guid>
    </item>
    <item>
      <title>Channel Modelling and Performance Limits of Vehicular Visible Light Communication Systems</title>
      <link>https://trid.trb.org/View/1737374</link>
      <description><![CDATA[Visible light communication (VLC) has been proposed as an alternative or complementary technology to radio frequency vehicular communications. Front and back vehicle lights can serve as wireless transmitters making VLC a natural vehicular connectivity solution. In this paper, the authors evaluate the performance limits of vehicular VLC systems. First, he authors use non-sequential ray tracing to obtain the channel impulse responses (CIRs) for vehicle-to-vehicle (V2V) link in various weather conditions. Based on these CIRs, the authors present a closed-form path loss expression which builds upon the summation of geometrical loss and attenuation loss and takes into account asymmetrical patterns of vehicle light sources and geometry of V2V transmission. The proposed expression is an explicit function of link distance, lateral shift between two vehicles, weather type (quantified by the extinction coefficient), transmitter beam divergence angle and receiver aperture diameter. Then, the authors utilize this expression to determine the maximum achievable link distance of V2V systems for clear, rainy and foggy weather conditions while ensuring a targeted bit error rate.]]></description>
      <pubDate>Wed, 21 Oct 2020 09:52:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1737374</guid>
    </item>
    <item>
      <title>Optimal resource utilisation algorithm for visible light communication-based vehicular ad-hoc networks</title>
      <link>https://trid.trb.org/View/1688023</link>
      <description><![CDATA[With the advent of visible light communication (VLC) and vehicular ad-hoc networks (VANETs), the realisation of the intelligent transportation system (ITS) is becoming a reality. In high-mobility networks such as VANETs packet transmission failure may occur frequently if network lifetime, connectivity, and load balancing are not considered during next-hop link selection. Optimal resource utilisation can address the network lifetime, network connectivity, and network load balancing problems in ITS. This study investigates the problem of optimal resource allocation for VLC-based VANETs. The authors present a multi-objective integer linear programming (ILP) model that optimises resource utilisation in VLC-based VANETs, wherein the objectives are maximising network lifetime, load balancing, and network connectivity. Illustrative numerical results demonstrate that their solution achieves promising results, however, for high vehicle density, the problem is intractable. Therefore, they proposed a heuristic algorithm that addresses the problem when vehicle density is high in a network. They demonstrate the benefits of the proposed algorithm by comparing their solution against optimal resource utilisation unaware strategy, wherein resources are assigned randomly without considering resource optimisation. Their experimental study shows that both the ILP model and the heuristic algorithm increase network performance in terms of maximising network lifetime, connectivity, and load balancing.]]></description>
      <pubDate>Tue, 30 Jun 2020 12:23:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1688023</guid>
    </item>
    <item>
      <title>Effect of injection timing on combustion and soot formation in a direct injection spark ignition engine fueled with butanol</title>
      <link>https://trid.trb.org/View/1625691</link>
      <description><![CDATA[Ever tighter restrictions on pollutant emissions, energy security and a continuous drive for improving fuel economy have extended the range of application for direct injection in spark ignition engines and promoted the use of alternative fuels. Direct injection features higher soot formation compared to external mixture preparation, and therefore, intensive research is performed for understanding the processes related to this pollutant category. This study looked into the effect of injection timing in a wall-guided direct injection spark ignition engine when gasoline was completely replaced with n-butanol. Thermodynamic measurements were coupled with optical investigations that provided improved insight into local distribution of diffusive flames during late combustion stages. These data were correlated with exhaust gas measurements of CO, HC and NOx, as well as opacity. The optimum setting for injection timing was found to be a compromise between intake airflow velocity and piston positioning that influenced wall impingement. Late injection resulted in reduced soot but higher HC emissions, as well as lower performance compared to the optimum point. Early fuel delivery had roughly the same effect on indicated mean effective pressure and stability, with the downside of increased opacity. These observations were detailed with data obtained through cycle-resolved imaging that showed different integral luminosities with respect to injection phasing and confirmed that fuel impingement on the piston crown is the main factor of influence for soot formation. Ultraviolet–visible spectroscopy in the late combustion phase was also applied in repetitive mode in order to provide better insight into cyclic variability of the emission intensity in the range specific for carbonaceous structures.]]></description>
      <pubDate>Wed, 18 Sep 2019 17:16:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1625691</guid>
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