Intelligent transportation systems (ITS) are designed to enhance road safety and traffic efficiency. Connected autonomous vehicles are a critical component of ITS, and platooning among vehicles can enhance close coordination and improve driving efficiency. This requires high-capacity links, which can be facilitated by light communication. However, due to the small area of optical photodiodes, the light communication link can suffer misalignment, leading to reduced reliability during maneuvering on-road curvatures. Solar panels present a potential solution having a larger receiver area and the ability to convert the optical signal to its electrical equivalent. However, solar panel 3-dB bandwidth for communication is limited to only a few tens of kHz range, resulting in low data throughput. In this work, we develop an analog circuit to enhance the 3-dB bandwidth of solar panel receivers, effectively mitigating misalignment issues by maintaining connectivity even at high orientation. Experimental results demonstrate that the solar receiver can maintain communication despite extreme misalignment of the order of ±50°. Furthermore, the results indicate that the solar panel can still provide connectivity even when 90% of its area is in blockage. Specifically, on the transmitter side, we have employed near-infrared light-emitting diodes (LEDs) to mitigate the glare effect caused by white LEDs. Also, IR LEDs cause less attenuation loss in outdoor environments, thus consuming less power than white LEDs to transmit information. Analytical expressions for designed analog circuitry and the impact of using solar panels in the dead zone are derived, and the comparison results with conventional photodiode is presented. The findings indicate that solar panels, when used as optical receivers, meet the communication requirements for the connected vehicles and effectively address issues such as loss of communication links.

Solar panels, traditionally used for energy harvesting, are emerging as viable optical receivers for visible light communication (VLC). This work investigates the impact of different solar panel configurations—series, parallel, and standalone (single panel)—on their performance as VLC receivers. A series configuration reduces junction capacitance, enhancing bandwidth and response time and making it ideal for high-speed optical communication. However, the increased impedance may affect signal reception efficiency. In contrast, a parallel configuration increases overall capacitance, which can limit bandwidth and slow response time but provide better signal strength. The single-panel configuration offers a balanced approach, ensuring efficient signal reception without additional circuit complexities. Experimental evaluations focus on key communication metrics such as bandwidth and solar panel time response. While the impact on energy harvesting is acknowledged, the primary emphasis is on optimizing signal reception for high-speed VLC applications. Solar panel enabled long distance communication links can enhance mid-haul and front-haul networking, extending connectivity to rural and remote areas.

MOTIVATION: Functionally important 'fold-switching' proteins, which do not obey the classical folding dogma, are now thought to be widespread. Algorithms that can accurately annotate fold-switching proteins from sequence information can help uncover the true extent of the 'metamorphome'. RESULTS: Here, we present Morpheus, a fragment-based classification approach, that works by analysing the diversity of structures within a query protein sequence. Morpheus exhaustively curates and uses fragment structural data from the Protein Data Bank as well as the AlphaFold Protein Structure Database. We employed our algorithm on 57 different proteomes consisting of a total of 601 218 proteins and identified about 10% of these proteins with the ability to fold-switch. Additionally, we provide a web server for Morpheus to test for fold-switching propensities for user-defined sequences (http://mbu.iisc.ac.in/∼anand/morpheus). Besides screening for fold-switching behaviour in proteomes, our work will be useful in de novo design and engineering of such proteins through further experimentation. AVAILABILITY AND IMPLEMENTATION: All codes used for fragment-picking analysis and the proteome-level prediction data for the 57 proteomes are publicly available on Zenodo (https://zenodo.org/records/14837336). The algorithm is also hosted within the web server (http://mbu.iisc.ac.in/∼anand/morpheus).

The future intelligent transport systems (ITSs) promise to improve traffic safety and security along with reducing the driver workload. In this article, we consider a pre-emptive emergency situation, wherein we design a safe-driving maneuver problem for transportation Metaverse (TransVerse) to compensate for driver reaction delay. The proposed scheme balances the risk of collision, and the spectral and computation resources required by the network. This combination of the spectral and computation resources required is also known as utility of the vehicular network. Further, an emergency maneuver is proposed to suggest a lane-changing maneuver based on the safe lane quality index for vehicles in vicinity of the emergency vehicle, also known as collision risk vehicles (CRVs). Moreover, based on the current position of the vehicles and the proposed safe maneuver, we propose a driving mode advisory to the drivers to provide a speed profile and a real-time high-level driving modes advice on acceleration, cruise, and engine brake. We evaluate the performance of the proposed safe-maneuver planning for CRVs in terms of collision probability, velocity, driving mode, and end-to-end lane changing delay. It can be observed that with the use of the proposed scheme, there is no effect on the performance of the high-CRV (HCRV). However, for the second following vehicle (HCRV2), the probability of collision decreases by 34.78%, and the velocity of the vehicle increases by 61.70% with the use of TransVerse. Moreover, a tradeoff between resource allocation and end-to-end delay of the network is also analyzed with and without TransVerse scenario.

In recent years, LiFi has become increasingly pop-ular as an indoor communication technology that utilizes the unlicensed visible light and infra-red spectrum to transmit data. A major challenge of utilizing LiFi is that its area of coverage is limited. Thus, a large number of LiFi access points (APs) is often complemented by deploying a WiFi AP to form a hybrid WiFilLiFi network. However, such deployment does not lead to any additional improvement in the performance of WiFi or LiFi APs. Recent WiFi APs are known to have high overhead due to the requirement of channel state information (CSI), which is essential for utilizing spatial multiplexing. Thus, in this work, we propose a system called WiLiConnect (WiFi-LiFi Connectivity with CSI), which communicates the CSI requirement of the WiFi channel through the LiFi APs, thereby reducing the overhead of WiFi APs. We formulate this problem of load-balancing the overhead of CSI sharing across the LiFi APs, and show that the general problem is NP-Hard. We then propose a round-robin algorithm to solve a special case of the problem, where all the users are assumed to have a single antenna. We further utilize extensive simulation to show that WiLiConnect significantly reduces the overhead of sending CSI. Specifically, WiLiConnect incurs only 0.06% overhead on a WiFi AP having 8 antennas on the total sum rate.

We study the handover (HO) rate and user performance in a large-scale three-dimensional (3-D) unmanned-aerial vehicle (UAV) network, where the UAVs are deployed to provide access to the ground mobile users in a disaster scenario. The 3-D network is modeled as a two-dimensional (2-D) homogeneous marked poisson point process (PPP), in which the marks represent the altitude of the UAVs. Due to the different altitudes marked for the UAVs, irregularly shaped Voronoi cells are formed, which is challenging to analyze. Leveraging the HO rate, we derive the signal-to-interference-plus-noise ratio (SINR) coverage probability and the average throughput experienced by mobile users. Based on the derived framework, we investigate the impact of the intensity of deployment and user speeds on the HO rate and throughput, which enables us to present several key system-design insights for such networks.

Future autonomous driving would require a plethora of networking resources and high-quality vehicular communication links. As these mobile devices are resource-constrained, thus, offloading computer-intensive operations to the mobile edge servers has been a crucial strategy to meet the stringent quality of service (QoS) requirements. However, various types of smart vehicles with distinct capabilities, dynamic demands, and unpredictable topology pose significant challenges in realizing efficient edge computing services. To cope with these challenges, we incorporate a digital twin (DT)-enabled con-nected vehicular network which can facilitate automated resource management to enhance QoS of vehicular users. Specifically, we aim to allocate computation and spectrum resources for a DT-enabled vehicular network along with designing an optimal offloading policy. In addition, a problem to optimize the vehicular network's utility-cost ratio (UCR) is formulated in order to reduce the overall latency, energy consumption, and to improve the throughput. Further, to obtain an optimal resource allocation framework, we propose a three-step iterative algorithm to optimize the bandwidth, prices for latency, energy consumption, and offloading factor iteratively until convergence. The simulations demonstrate that the suggested approach efficiently reduces the task offloading latency as well as decreases the average energy usage for vehicular network, in addition to improving the throughput. Specifically, the utility-to-cost ratio decreases by 85 % and 12.5 % for sparse and dense traffic scenarios, respectively for a vehicle density of 0.137 vehicle/m.

The platooning of autonomous vehicles on highways is an emerging concept attracting significant interest due to its potential to enhance highway safety by enabling vehicles to closely follow one another, reducing reaction times for accidents, cooperative adaptive cruise control, mitigating human errors, reducing fuel consumption, and improving traffic utility. This paper proposes the integration of vehicular visible light communication (VLC) or radio frequency (RF) based technology over infrastructure-to-vehicle (I2V) and vehicle-to-vehicle (V2V) communication links to support desirable quality of service (QoS) requirements in vehicular platoon networks. We simulate possible integration architectures encompassing RFNLC-based I2V with the RFNLC-based V2V link. The proposed work also explores the benefits and trade-offs of integrating the RFNLC-based I2V with the RFNLC-based V2V, specifically for vehicular platoon networks. We evaluate and compare these proposed architectures in terms of data rate and bit-error-rate (BER) under varying weather conditions. The obtained simulation results demonstrate the potential of this proposed hybrid architecture for I2V and V2V links, which could leverage the strength of standalone RF and VLC technologies. The RF-based I2V and VLC-based V2V hybrid architecture emerge as a standout performer, excelling in terms of communication range and resilience to challenging channel conditions.

Visible light communication (VLC) has enabled the inception of a novel communication technique due to its high bandwidth and resistance to interference from various electromagnetic sources. However, in an indoor VLC system, other users (static as well as dynamic) can act as blockages to the communication link for the desired user. In this paper, we analyze the performance of an indoor VLC system with dynamic human blockages. Specifically, we use the random waypoint (RWP) model to characterize the movement of the blockages. The system performance is analyzed for a 4-LED configuration, where the blockages can pause during the movement for a specific pause time. Further, we developed a model to calculate the blockage probability in a typical indoor space, which is consequently used to calculate the power at the VLC receiver. Additionally, the analysis is extended for multiple blockage scenarios with different pause times. The second-order statistics such as level crossing rate (LCR) and average fade duration (AFD) have been examined to demonstrate the impact of both pause time and the number of blockages on this dynamic time-varying indoor VLC channel. It is observed that a blockage with a longer pause time will have a longer average outage duration (AOD). Finally, the effect of the velocity of blockages on LCR and AFD is also analyzed. We believe that the insights obtained in this paper will be useful to the operator while deploying an indoor VLC communication system in the presence of dynamic blockages.

In view of recent developments in underwater wireless technology and the continuous demand for deep ocean exploration, this study investigates the underwater optical wireless communication system. Underwater wireless optical communication (UWOC) has several benefits over short-distance wireless connectivity due to its significantly higher bandwidth and data rate compared to acoustic communication. This paper presents an analysis of a non-line-of-sight (NLOS) UWOC system configuration using a submerged optical intelligent reflecting surface (OIRS) that is used to support multiple users by allocating different OIRS elements to various users at the receiver end. To increase the average sum rate and preserve user fairness, techniques based on equal mirror assignment (EMA) and distance-based mirror assignment (DMA) are presented. The outcomes are evaluated against conventional orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) schemes for underwater communications.

This paper studies an unmanned aerial vehicle (UAV)-aided downlink sparse code multiple access (SCMA) sys-tem to serve multiple users under finite resources. The objective of this work is to maximize the average sum-rate of UAV-SCMA system by optimizing the three-dimensional (3D) UAV trajectory within the UAV energy and mobility constraints, and the inter-user interference in SCMA. The formulated problem is non-convex in nature, we reformulate it using logarithmic approximation and solve it iteratively. The simulation results validates that the proposed UAV 3D trajectory outperforms the benchmark schemes with around a 20% increase in the overall sum-rate under the available energy budget.

Optical intelligent reflective surface (OIRS) is one of the promising solutions to address the ‘skip-zone’ problem between the base stations and the mobile users. The performance of OIRS can be further complemented by mounting them on unmanned aerial vehicles (UAVs), which are known for their flexibility and maneuverability. The proposed work aims to utilize the OIRS-assisted UAV to improve the performance of optical wireless communication (OWC) systems. In this work, multiple mirror elements of the OIRS are grouped and assigned to the user. Specifically, a novel mirror element assignment scheme is proposed, namely a signal-to-noise ratio (SNR) based mirror assignment (SMA) to achieve maximum user throughput with proportional fairness for each user. The performance of the proposed SMA scheme is compared against the equal mirror assignment (EMA) scheme and well-known conventional bench-mark approaches, e.g., time-division multiple-access (TDMA) and non-orthogonal multiple access (NOMA). The results are reported in terms of average sum rate, fairness, and capacity outage probability. The obtained results show that the proposed SMA scheme outperforms EMA, TDMA, and NOMA schemes.

In order to facilitate low latency vehicle-to-infrastructure (V2I) communication, latency sensitive solutions for resource allocation should be explored. In our paper, we propose a novel wavelength allocation algorithm for a fiber-wireless (FiWi) based V2I communication network. Specifically, we propose a novel approach for wavelength allocation in a time and wavelength division multiplexed passive optical network (TWDM-PON) by utilizing a first-fit bin packing algorithm. The TWDN-PON forms the optical backhaul of our FiWi network. The proposed algorithm is hybrid in nature, i.e., it utilizes both static and dynamic wavelength allocation. Further, the proposed algorithm enables an hourly allocation of wavelength to each optical network unit (ONU), connected to a roadside unit (RSU), whilst reducing the switching between the wavelengths and hence, consequently reducing the latency in the optical link. The proposed bin packing algorithm has been compared with conventional first-fit bin packing algorithm. It has been shown that by utilizing the proposed algorithm, the total number of wavelength switches reduces by 65 in 12 hours duration as well as the latency of the optical network reduces by 40% per ONU when compared with the conventional bin packing algorithm.

This paper presents a bandwidth enhancement circuit that enhances the 3 dB bandwidth of an off-the-shelf solar panel based receiver system for optical wireless communication. Experiment results show enhancement of the 3 dB bandwidth from 163 kHz to 1.62 MHz. A data rate of 1.5 Mbps is achieved with the OOK modulation scheme over the VLC link of 1 m. To the best of our knowledge, this is the highest data rate using solar panel as a receiver with OOK modulation. Low-cost, larger receiving area, ease of integration with other devices make the proposed system an environment-friendly and energy-efficient solution for optical wireless communication.

In this paper, we have determined the optimum pair of light-emitting diode (LED) semiangle and the receiver field-of-view (FOV) in the presence of human blockages for indoor visible light communication (VLC) system. Firstly, we have calculated the optimum value of LED semiangle and the receiver FOV independently, keeping others constant. Secondly, we have jointly optimized both the LED semiangle and the receiver FOV. In the analysis, both LoS and NLoS up to the second-order have been considered. We have also incorporated the reflections from the human body, essentially the skin and the clothes, in the analysis as it impacts the received power. In order to obtain the optimum value of the LED semiangle and the receiver FOV, we have used the quality factor (Q) as a performance metric. In addition, the analytical expression for the achieved quality factor is derived for both single variable and joint optimization formulation. Results shows that with 2 and 5 blockages, the optimum pair using single and joint optimization is (63°, 65°) and (63°, 70°) for a separation distance of $D_{1}=40~{\mathrm cm}$ and (65°, 70°) and (65°, 75°) for $D_{2}=20~{\mathrm cm}$ respectively which provide the highest quality factor with minimum delay spread shown. Furthermore, the optimization analysis can also be mapped to different room sizes and LED placement, with static and dynamic blockages inside the room.

The Light Fidelity (LiFi) and Wireless Fidelity (WiFi) technologies operate in non-overlapping spectrum, thus, a user is capable of receiving data concurrently from both LiFi and WiFi Access points (APs). Therefore, facilitating a link aggregation (LA) enabled heterogeneous LiFi-WiFi network (HLWN). In this paper, we have analysed the performance of LA enabled HLWN by utilizing an LA based on SINR (LA-SINR) algorithm and compared it with the conventional indoor access networks like the hybrid LiFi-WiFi, standalone WiFi and standalone LiFi. Additionally, an intuitive LA for enhancement of QoS (LA-EQoS) algorithm has been proposed to further improve the quality of service (QoS) and average data rate performance of LA enabled HLWN. The simulation results validate that for a predefined QoS requirement, proposed LA-EQoS provides 80% to 100% coverage for more number of users as compared to other networks. Moreover, for a given outage constraint, the maximum QoS offered by LA-EQoS is 1.5 times higher than other networks. 16

Reconfigurable intelligent surfaces (RISs) have recently been envisioned to provide an adaptable channel for futuristic wireless communication networks. In this work, we investigate a downlink RIS-aided non-orthogonal multiple access (NOMA) wireless networks, where a RIS is deployed to enhance users’ performance communicating with the base station (BS) in the presence of a non-ideal transceiver. Specifically, closed-form expressions for the outage, spectral efficiency (SE) and energy efficiency (EE) are derived. The results demonstrate that the non-ideal transceiver has a detrimental impact on the performance of the RIS-aided NOMA system. The proposed analysis also shows that for a RIS-aided NOMA system with a non-ideal transceiver, there exists an upper bound on SE that is independent of the transmit power and the number of reflecting elements in the RIS. Additionally, the performance of the NOMA system is compared with its OMA counterpart, where the results show that for a non-ideal transceiver-based system, the RIS-aided NOMA outperforms OMA.

Visible light communication (VLC) has recently emerged as an affordable and scalable technology supporting very high data rates for short range vehicle-to-vehicle (V2V) communication. In this work, we advocate the use of vehicular-VLC (V-VLC) for basic safety messages (BSMs) dissemination in lieu of conventional vehicular radio frequency (V-RF) communication in road intersection applications, where the reception performance is affected by interference from the concurrent transmissions of other vehicles. We make use of stochastic geometry to characterize the interference from the same lane as well as the perpendicular lane for various network configurations, i.e., standalone V-VLC, stand-alone V-RF and hybrid V-VLC/V-RF network. Specifically, by modelling the interfering vehicles’ locations as a spatial Poisson point process (PPP), we are able to capture a static two-dimensional road geometry as well as the impact of interference due to vehicles clustering in the vicinity of road intersection in terms of outage probability and throughput. In addition to above, the performance of spatial ALOHA and carrier sense multiple access with collision avoidance medium access control (CSMA/CA MAC) protocol for standalone V-VLC, standalone V-RF and hybrid V-VLC/V-RF network configuration for relaying BSMs at road intersection is also compared. The performance metrics such as delay outage rate (DOR) and information outage rate (IOR) are utilized to investigate the impact of latency associated with various network configurations. Our numerical results reveal that our proposed hybrid V-VLC/V-RF leads to significant improvement in terms of outage performance, throughput and latency as compared to stand-alone V-VLC or stand-alone V-RF network.

In this paper, we consider a fiber-wireless (FiWi) network consisting of 10-Gigabit-capable passive optical network (XG-PON) and wireless fidelity (WiFi). In order to mitigate the conventional limitations of grid-power supply, an off-grid FiWi network is considered, where the components of the network such as optical network units (ONUs) and IEEE 802.11 access points (APs) are powered using renewable sources of energy such as photovoltaic (PV) panels and wind turbines along with batteries. Depending on the availability of renewable power at different locations, the energy resources available to power ONU-AP may vary. Consequently, we propose a joint energy resource allocation framework to minimize the number of PV panels and batteries required by ONU-AP based on its location as well as throughput requirement of the users. An analytical framework is derived to justify the accuracy of the proposed joint energy resource allocation framework. Further, a socio-economic analysis and trade-off analysis between allocation efficiency and cost is also presented. The results show a good agreement between the analytical and the proposed approach. It has also been observed that location with high renewable energy sources contributes to a significant reduction in the number of PV panels and batteries requirement and, therefore, has lower cost and carbon dioxide (CO2) emissions.

An intelligent reflecting surface (IRS) comprises of an array of discrete reflective elements (REs) possessing re-configurable scattering properties. IRS has the capability to beamform and relays the received radio signal from the transmitter to the desired receiver. This has made the IRS a promising candidate technology for the beyond fifth-generation (5G) cellular standards. In this work, the performance of an IRS-assisted wireless communication system is investigated and compared with the full-duplex (FD) relay-assisted system in the presence of non-ideal transmitters. Specifically, the performance is compared in terms of channel capacity and energy efficiency (EE). The results show that the IRS can never achieve more capacity than the ideal FD relaying, in the presence of a non-ideal transmitter, irrespective of the placement of IRS and relay. Further increasing the number of REs, the capacity saturates with an upper bound that equals to the capacity provided by the relay-assisted system. However, increasing the number of REs results in the reduction of the EE for IRS-assisted systems, which are otherwise known to be highly energy-efficient.

Light fidelity (LiFi) is an emerging communication technology that utilizes light intensity modulation in order to transfer data from light-emitting diode (LED) to users. Due to the vast visible light spectrum, LiFi can support high data rates; however, its coverage is limited. In contrast to LiFi, WiFi works in radio frequency and is capable of providing ubiquitous coverage with limited data rates. Since the spectrum of LiFi does not overlap with WiFi, both can co-exist to form a hybrid LiFi and WiFi network. The advantage of hybrid LiFi and WiFi network is that it provides high data rates and better connectivity. The performance of a hybrid LiFi and WiFi network significantly depends upon the load balancing strategies. Therefore, in this paper, gradient descent-based reinforcement learning (RL) has been proposed to determine an optimal access point (AP) assignment policy that aims to maximize the average network throughput while ensuring user's satisfaction. The performance of the proposed method is then compared against conventional signal strength strategy (SSS); the results are presented in terms of the average network throughput, user satisfaction, and outage probability. Based on the results, it was observed that the proposed RL method provides a significant improvement in all the performance metrics over the SSS based method.

Unmanned aerial vehicles (UAVs) have the potential of being used as flying base stations to facilitate a disaster-resilient communication network. However, the optimal placement of UAVs over a disaster-affected area must be aware of the mobility of the ground users. Hence, in this paper, we propose a ground user mobility aware multi-UAV placement strategy for disaster-resilient communication network. We formulate an optimization problem to maximize the number of ground users covered by the UAVs, while also taking into account the UAV flight time constraint. Specifically, in this work, the emergency first responders (EFRs) are considered as the ground users and their mobility is modeled in the disaster-affected area. We analyze single-UAV and multi-UAV scenarios in terms of average covered users and average coverage time. We observe that there exists a trade-off between the average number of covered users and average coverage time.

Energy efficiency (EE) and spectral efficiency (SE) are among the key performance metrics for any wireless standards. In this work, we study the trade-off between EE-SE for supporting the downlink data rate as well as opportunistically harvesting the ambient radio frequency (RF) energy. The goal is to maximize EE while maintaining the requisite data rate for the downlink. We consider a case of downlink full duplex multi-input single-output (MISO) system where the transmitter having multiple antennas is transmitting to a user equipped with single antenna. At the transmitter, few antennas are reserved for selfenergy recycling (S-ER) while the remaining antennas are utilized for information transmission. S-ER enhances the EE of the system at the expense of SE due to loss in the array gain. In order to improve the SE, we incorporate the adaptive S-ER scheme which utilizes selection of antennas corresponding to higher gains for information transmission. This compensates the loss in the SE along with the increase in EE of the system. Both linear and nonlinear transmitter cases have been considered for analyzing the trade-off and the simulation results are shown by obtaining the outage probability.

This paper proposes a framework to analyze the viability of network-assisted Device-to-Device (D2D) communication in an indoor propagation environment using location awareness. Based on the past location information of the users a probability model is developed. The model helps to evaluate the probability of a user's location on a specific indoor site at a given time of the day. Further, leveraging this location information, a heterogeneous framework is considered where user devices are capable of supporting cellular, as well as D2D communication. In order to quantify the performance, the proposed D2D+cellular framework is compared with the conventional cellular framework, and the gains are measured in terms of spectral efficiency and amount of energy saved. It is shown, on opting D2D over cellular for indoor communication it is possible to achieve an average spectral efficiency gain of 10.45 bits/s/Hz as well as an average energy saving of 59%. Further, it is also observed that there exists a critical point beyond which D2D ceases to be beneficial over conventional cellular communication.