With India committing to net-zero emissions by 2070, region-specific, long-term capacity expansion planning has become essential to facilitate a sustainable and economically viable energy transition. This study focuses on the western regional grid of India - one of the country’s five interconnected power regions - to explore least-cost, low-carbon transition pathways using the open-source modeling platform Switch 2.0.7. A total of 71 future scenarios are simulated to evaluate alternative energy-mix strategies for 2050 under varying policy constraints, thermal phase-out levels, and solar penetration levels. The study investigates whether full decarbonization is achievable without nuclear additions and, if not, identifies the minimum nuclear and battery energy storage system (BESS) requirements to ensure zero unserved load. Results indicate that a 75% reduction in existing thermal capacity is feasible with minimal nuclear expansion, while the most robust scenario includes 11.26 GW of new nuclear capacity and 152.4 GW of energy storage. To enable this transition, an estimated annual investment equivalent to 2.5% of the combined GDP of the region’s states will be required over the next 25 years. These findings offer critical insights for policymakers, emphasizing the importance of strategic, region-specific planning and investment to meet India’s long-term climate goals.

This paper investigates low-carbon and zero-carbon alternative energy transition scenarios based on the eastern region of India to reduce the high dependency on coal. This subnational model emphasizes different decarbonization scenarios based on various technical and economical parameters and constraints. In this study, leastcost scenarios are developed by customizing various parameters specific to this coal-rich region. Switch, an opensource energy modelling platform, is used in this study to develop the scenarios for different target years. When demand-side flexibility (DSF) is included in the formulated scenarios, the requirement for overall installed capacity for the target years is also reduced. The storage requirement also depends on the capacity addition of alternative resources across different target years. By 2050, under the renewable energy sources with nuclear along with DSF applications (DSFRN) scenario, the storage requirement is reduced by 80 % with the integration of DSF. Under the thermal mix with nuclear along with DSF application (DSFTMN) scenario, this requirement is reduced by 59 %. The land requirements for the capacity addition of solar, wind, and nuclear energy collectively under the DSFTMN and DSFRN scenarios are 2.64 % and 2.69 %, respectively. Carbon emissions are also reduced by 93 % and 96 % under the TMN and DSFTMN scenarios, respectively, compared to the regular as usual (RA) scenario by 2050.

In this work, we propose a dynamic field-of-view (FoV) visible light communication (VLC) receiver system to mitigate inter-cell interference (ICI) in multi-cell indoor environments. Twisted nematic liquid crystal (TN-LC) cells are employed as tunable optical filters that can switch between ON and OFF states, enabling dynamic adjustment of the receiver's FoV (12 degrees - 41 degrees) based on its position. This adaptive FoV capability effectively suppresses unwanted ICI and significantly enhances the signal-to-interference-plus-noise ratio (SINR). Furthermore, with the proposed receiver architecture, the average SINR is maintained at 51 dB, while the maximum SINR reaches up to 79 dB.

The integration of reconfigurable intelligent surfaces (RIS) into the receiver section of indoor visible light communication (VLC) systems is still in its early stages. Although amplification in the optical domain is achievable using liquid crystal (LC)-based RIS, the lack of a precise and adaptable channel model hinders its effective design and application. In this study, we demonstrate how a liquid crystal-based RIS can be integrated with the receiving unit of an indoor VLC system and highlighted its role as an optical amplifier controlled by external voltage. We also identified the shortcomings of the existing VLC channel model with tunable LC receivers and proposed a robust analytical framework to more accurately estimate signal strength. Furthermore, the impact of external tuning voltage on the transmission coefficient and amplification gain factor of the LC cell is analyzed in detail.

The recent release of the IEEE 802.11bb-2023 global light communication standard opens up exciting opportunities for LiFi-enabled devices to work seamlessly with RF technology. In this study, we extend our previously reported research on freeform-based angle diversity receiver by using it for a multiuser indoor hybrid LiFi-RF framework. The network performances have been investigated in terms of throughput, packet loss ratio and latency. The off-axis quadrilateral field of view of the freeform-based receiver offers excellent resilience against inter-channel interference. The result shows, nearly 300 Mbps average user throughput when 10 users are in motion inside the indoor environment. Moreover, exemplary improvement in overall system throughput has been observed compared to state-of-the-art research in the presence of light-path blockage.

This paper argues that a fit-for-purpose model and datasets are necessary to generate transition pathways for the electricity generation sector at the subnational level. We present the methodology, data, and results focusing at a sub-national level, the state of West Bengal in India. The approach can be generalized for any region with necessary customization. By utilizing high-resolution spatio-temporal input datasets, this study proposes a power sector capacity expansion model to compute three sets of transitional scenarios and one set of the current-as-usual scenario. These scenarios consider sub-national energy carrier-resource constraints and are solved to identify the most economically cost efficient future transition pathway for the electricity sector in West Bengal. Based on the least-cost solution, computations determine the optimal energy mix, operations, investments, and emissions for alternative scenarios. The results show that integrating demand-side flexibility (DSF) as a balancing option can lead to transformative outcomes. Compared to the current capacity expansion trend (ScenCA), adopting a thermal mix renewable scenario with intraday load-shifting (ScenTMDSF) could reduce 77% of CO2 emissions by 2040. This does not necessitate early retirement of existing thermal power plants, total investment increases by 13% compared to ScenCA. Without DSF as a balancing option, an additional 26% investment is required compared to the current-as-usual scenario for 2040. Transitioning to 100% renewable energy (ScenREN) requires 30% more investment, early retirement of 5.34 GW of thermal capacity, and nearly 2.7 times more storage battery capacity. These numbers help in understanding the magnitude of the financial resource and kind of technological need for the developing countries not only from the point of view of equitable climate action from burden sharing and just transition principles but also provides practical example of need for redirecting global capital for creating global good through subnational scale actions.

We report the effect of integrating metasurface-aided reconfigurable intelligent surfaces (RISs) on the signal-tointerference-plus-noise ratio (SINR) and data rate of a multi-cell visible light communication (VLC) system. RIS has been deployed in the channel between transmitter and receiver to redirect the reflected light in the desired directions, even in the absence of line-of-sight (LoS) links. Results show that the introduction of RIS has improved average SINR but reduced average illumination level compared to a no-RIS system. As the quantity of RIS increases, a discernible improvement in the maximum SINR value is observed. Here, three different receiver geometries, namely, a photodiode (PD), freeform diversity receiver (FDR), and modified FDR (MFDR), have been adopted. The impact of individual receivers has been reported in the presence of light path blockage. MFDR geometry is found to be most suitable with more coverage probability compared to the other two receivers. With (40 cm x 24 cm) RIS area, during blockage, MFDR maintains an average SINR of 21.95 dB, which is 97.29% and 14.24% greater than PD and FDR, respectively. (c) 2024 Optica Publishing Group

In order to accommodate high data traffic, the co-deployment of heterogeneous networks like light fidelity (Li-Fi) and wireless fidelity (Wi-Fi) can offer supplementary small-cell layers of support and bring about a paradigm shift in achievable system throughput and quality of service. However, dense deployment of Li-Fi access points(APs) in an indoor arena often leads to co-channel-interference (CCI) that can be fruitfully diminished by adopting a customized optical front-end called freeform diversity receiver (FDR). With regard to multi-user association, this work judiciously imparts the motivation behind the adoption of FDR in a hybrid Li-Fi Wi-Fi network (HLWNet). Based on different mobility scenarios and blockage conditions the performance of the proposed HLWNet has been evaluated. A Li-Fi channel model with FDR and a rule-based resource allocation algorithm (RBRA) has been proposed for the purpose. Nevertheless, the network data quality of the multi-user system has been estimated in terms of packet loss, latency, and fairness index. Unlike the existing optimal resource allocation (ORA), the RBRA demonstrates superior network performance. Additionally, the execution time in the RBRA is reduced by a factor of 89 compared to the optimal resource allocation algorithm. Simulation results show a satisfactory fairness index of more than 0.85 and latency within 2.1 ms for a 10-user association inside an indoor environment of 25m2 floor area. In the absence of LOS blockage, the system throughput exhibits minimal variation, staying consistent for both methods with less than a 2% difference. However, significant improvement in average user throughput and effective system throughput has been observed compared to the existing studies. Despite line-of-sight (LOS) blockage, the proposed system with RBRA consistently maintains throughput within the range of 2.01 Gbps to 2.55 Gbps. The average user throughput, varying from 182 Mbps to 480 Mbps, is contingent upon the number of associated users, which ranges from 4 to 14.

The several advantages of visible light communication (VLC) have made it a potentially competent candidate for future communication technology. The reliability of the VLC system depends on the line-of-sight (LOS) links. However, surrounding environments pose unique challenges, frequently causing LOS blockages. The reconfigurable intelligent surfaces (RIS) also known as intelligent reflecting surfaces (IRS) is a collection of tunable passive elements that have proven their ability in RF communication to manipulate and control the transmitted/reflected RF signals by changing the orientation or phases of RIS. RIS is anticipated to play a crucial role in enhancing VLC by shadowing compensation, extending coverage by controlling the beam directions and improving communication reliability by mitigating interferences. This work delves into the emerging field of reconfigurable intelligent surfaces (RIS) and their transformative role in multi-cell indoor visible light communication (VLC) systems. A RIS-based indoor multi-cell system model is developed for the purpose of mitigating inter-channel interference (ICI) issues during LOS blockages. The SINR performance of the proposed system is estimated for four different scenarios. Results show that the integration of RIS in between VLC channels can enhance the detector’s received power up to 27 times compared to the power received from the LOS and NLOS channels. Moreover, incorporating RIS has raised the average SINR value by 25% during no blockage and more than 70.4% during the blockage.

Abstract In recent time of looming radio frequency (RF) spectrum crisis, visible light communication using lighting infrastructure emerged as a potential alternative at an indoor environment. This paper addresses the setback associated with ambient light interference in an indoor Visible Light Communication (VLC) system to ensure joint communication and illumination performance inside an office room. A novel VLC architecture with suitable white light emitting diode (WLED) luminaire arrangement is presented to minimize the dispersion of signal to interference plus noise ratio (SINR) across the room. Luminaires are categorized in two groups viz. data transmitting illuminants and illuminants for lighting purpose. The first group is dedicated to transmit data as well as serves the purpose of illumination. The other set creates only ambient illumination to achieve quality lighting attributes. The proposed forward error corrected receiver configuration discards the ambient light noise originated by the illuminants that serve the ambient illumination. Tail biting convolutional encoder and viterbi decoder are used at the encoding section of the transmitter and decoding section of the receiver respectively to improve bit error rate. Results obtained through MATLAB simulation shows better average bit error rate (BER) in the order of 10 −8 measured at uniformly distributed 25 grid points over the working plane. At the same time achieved average horizontal illuminance with good uniformity comply with ISO recommendation.

A Li-Fi receiver front-end is proposed using monolithic-freeform-Fresnel profile. The modified design replaces four orthogonally oriented optical front-end into a single unit and exhibits 81 dB average SINR with more than 25% reduction in dimension.

The prospect of utilizing freeform optics to develop a more compact and smaller VLC receiver front-end is explored in this study for a multi-cell indoor environment. A novel freeform surface element (FSE) has been fabricated by an ultra-precision single-point diamond turning (SPDT) machine and characterized by the mechanical and optical profiler to investigate its potential use inside a freeform diversity receiver. A 9 dB increment in average signal-to-interference-plus -noise-ratio (SINR) is observed after third iteration while the form error reduces to 1.92 mu m. The communication functionality of the fabricated FSE is also validated experimentally. The average SINR over the communication floor is computed as 109.29 dB. The fabricated freeform element is further modified to a freeform Fresnel profile for more compactness. The result shows, a substantial decrease in receiver height (2.314 mm) is possible using the proposed approach. Moreover, different fabrication challenges related with freeform Fresnel have been identified and discussed to set the future research pathway.

We report the design of a modified angular diversity receiver (ADR) with reduced size and improved communication performance for indoor VLC applications. The proposed design has four freeform and one spherical lens mounted on five co-planer photodiodes. An extended polynomial surface is used to determine the slope of the freeform lens with a quadrilateral off-axis field of view (FoV) (28° × 28°). Four identically designed freeform lenses are placed in a 2×2 format keeping 90° angular separation. Due to the orthogonal slope alignment of the proposed structure, the angular diversity is established. The distinct off-axis FoV of the freeform lenses introduce an uncorrelated channel gain in a multiple-input multiple-output (MIMO) VLC framework. A spherical lens with a narrow FoV (~15°) is also placed at the middle of quadrupole freeform lenses to ensure high SINR of 156 dB when the receiver approaches to the nadir of any transmitter. The compact physical dimension of the designed receiver structure (11.2 mm × 11.2 mm × 6.1 mm) is highly advantageous to facilitate VLC at any handheld gadget. Considering a square indoor environment (5m × 5m × 3m), an excellent average SINR performance of 95.7 dB is observed over the communication floor.

This paper introduces a novel and promising design of a freeform diversity receiver (FDR) to reduce the interchannel interference (ICI) of multi-cell visible light communication (VLC) system. Based on the potential of rotationally non-symmetric freeform optics, we have established the design of an off-axis VLC receiver frontend. In this study, we have performed the detailed design of the freeform surface profiles and have analysed the corresponding fabrication tolerances. Nonetheless, the communication performance of the VLC system using the proposed design has been evaluated with the help of Monte-Carlo based ray-tracing technique. Results show that the system with the proposed FDR significantly outperforms the existing state-of-the-art multi-cell VLC receivers in terms of signal-to-interference-plus-noise ratio (SINR). The spatial SINR ranges from 98 dB to 137 dB while 120.5 dB average SINR is attained over the communication floor. This compact size receiver (15.12 mm x 15.12 mm x 6.76 mm) with substantial wireless reception reliability has prospective future applications in the emerging field of visible light communication and its counterpart Li-Fi.

To achieve improved communication and illumination performances of a multi‐cell indoor visible light communication system, the selection of transmitter configuration and receiver's field of view (FoV) play a critical role. Based on multiple criteria decision modeling, a design‐centric methodology is proposed in this paper to determine the optimal transmitter configuration and receiver's FoV under lighting constraints. These optimal parameter selections are instrumental to obtain a highly uncorrelated channel, thus significantly mitigate both co‐channel interference from the neighboring transmitter and intersymbol interference due to multipath reflection. The implication for the optimum selection is explored using two communication (P‾sig,P‾intf) and two lighting (Eavg, UO) performance indicating metrics. For a typical indoor scenario, three different transmitter arrangements with varying half‐power beam‐width are considered as alternatives. Furthermore, the signal to interference plus noise ratio (SINR) is tested over the communication floor (CF) by a simple receiver structure with a single photodiode. Incorporating the optimal transmitter configuration and receiver's FoV, 36.13 dB average SINR and 345 lx average horizontal illuminance is achieved. Analytically obtained SINR is also validated using a commercial ray tracing optical software for different positions over the CF. In comparison with the state of the art non‐optimal and sub‐optimal solutions, the proposed scheme, without real‐time computational complexity exhibits noteworthy improvement in SINR performance at expense of a trivial drop in overall uniformity of horizontal illuminance.

This study evaluated a potential transition of India’s power sector to 100% wind and solar energy sources. Applying a macro-energy IDEEA (Indian Zero Carbon Energy Pathways) model to 32 regions and 114 locations of potential installation of wind energy and 60 locations of solar energy, we evaluated a 100% renewable power system in India as a concept. We considered 153 scenarios with varying sets of generating and balancing technologies to evaluate each intermittent energy source separately and their complementarity. Our analysis confirms the potential technical feasibility and long-term reliability of a 100% renewable system for India, even with solar and wind energy only. Such a dual energy source system can potentially deliver fivefold the annual demand of 2019. The robust, reliable supply can be achieved in the long term, as verified by 41 years of weather data. The required expansion of energy storage and the grid will depend on the wind and solar energy structure and the types of generating technologies. Solar energy mostly requires intraday balancing that can be achieved through storage or demand-side flexibility. Wind energy is more seasonal and spatially scattered, and benefits from the long-distance grid expansion for balancing. The complementarity of the two resources on a spatial scale reduces requirements for energy storage. The demand-side flexibility is the key in developing low-cost supply with minimum curtailments. This can be potentially achieved with the proposed two-level electricity market where electricity prices reflect variability of the supply. A modelled experiment with price signals demonstrates how balancing capacity depends on the price levels of guaranteed and flexible types of loads, and therefore, can be defined by the market.

We propose a multi-parameter optimized hemispheric angle diversity receiver (HADR) for multiple-input multiple-output (MIMO) indoor visible light communication (VLC) system. Compared with the existing angle diversity receiver the proposed optimal HADR exhibits two main advantages. The fluctuation in spatial signal to interference plus noise ratio (SINR) is significantly reduced irrespective of random rotation angle (RRA) of the circular structure and helps to improve the mobility inside the indoor environment. On the other hand, average SINR over the communication floor is considerably increased by negating the co-channel interference (CCI). Both theoretical analysis and computer simulation is presented to establish the communication performance of the proposed HADR. Result shows 45.17% reduction in spatial SINR fluctuation with a consistency factor of 0.978 by incorporating optimal field of view (FOV) and inclination angle. Simultaneously excellent average SINR of 48.81 dB is obtained.

In an indoor space, visible light communication (VLC) can form a promising enhancement of future illumination infrastructures with communication functionalities. This illumination infrastructure consumes 20% of the total energy consumption in the world. In this perspective, daylight integration with indoor VLC system is a promising area of research to conserve a considerable amount of energy. This paper deals with the design and practical realization of an energy‐efficient indoor VLC system through daylight integration. Dimming control mechanism using continuous current reduction topology is adopted to design the transmitter section of the VLC system. Thrust has been given to accomplish the required communication performance in terms of the bit error rate and illumination performance in terms of average horizontal illuminance and short‐term flicker severity. Both the communication and illumination performances have been evaluated under five different daylight conditions. At maximum ambient daylight condition, 37.29% of total energy has been saved, while the bit error rate lies in the order of 10 −10 . Simultaneously, satisfactory illumination performance in accordance with international guidelines has been achieved.

In an office space, an LED-based lighting system allows you to perform the function of a data transmitter. This article discusses the cost-effective design and development of a data-enabled LED driver that can transmit data along with its receiving part. In addition, this paper clearly outlines the application of the proposed VLC system in an office environment where ambient light interference is a severe issue of concern. The result shows satisfactory lighting characteristics in general for this area in terms of average horizontal illuminance and illuminance uniformity. At the same time, to evaluate real-time and static communication performance, Arduino interfaced MATLAB Simulink model is developed, which shows good communication performance in terms of BER (10–7) even in presence of ambient light noise with 6 dB signal to interference plus noise ratio. Our designed system is also flexible to work as a standalone lighting system, whenever data communication is not required.