De-Noising Scheme for VLC-Based V2V Systems; A Machine Learning Approach

• Core Innovation & Objective • Developed a novel, integrated system architecture combining a modified USRP X310 software-defined radio platform with a custom-designed high-power LED optical transceiver. • Achieved high-speed, low-latency, and highly reliable audio-video transmission over Visible Light Communication (VLC) for intelligent transportation and vehicle-to-vehicle (V2V) applications, particularly in electromagnetically sensitive environments. • Key Technical Breakthroughs • LED Bandwidth Extension: Designed an innovative active pre-equalization circuit (based on a 4th-order high-pass RC bypass and op-amps) that dramatically increased the 3dB modulation bandwidth of a commercial 15W LED from 3 MHz to 120 MHz. • High-Speed Modulation: Successfully implemented 64QAM-OFDM modulation/demodulation using GNU Radio on the USRP, enabling spectrally efficient data transmission. • Advanced Optical Design: Custom-designed optical lenses (transmitter and receiver) and a high-power Bias-T circuit for efficient AC/DC coupling, ensuring the LED operates in its linear region and maximizing optical power transfer. • Stable Link Performance: Incorporated an Automatic Gain Control (AGC) circuit at the receiver, stabilizing the output voltage between 1.2V - 2.0V and maintaining a modulation signal-to-noise ratio (SNR) > 23 dB over varying distances. • Outstanding System Performance • The experimentally demonstrated performance metrics are exceptional for a VLC system: • Peak Data Rate: 500 Mbps • Communication Distance: 0 - 110 meters • Bit Error Rate (BER): As low as 1.74 × 10⁻⁵ (far below the 1 × 10⁻⁴ target) • End-to-End Latency: < 0.1 s • Beam Angle: 11.5° (Transmitter) • Field of View (FOV): ≤ 18° (Receiver) • System Integration and Design • Hardware-Software Co-Design: Seamless integration of the USRP X310 (handling digital baseband processing) with the custom analog optical front-end. • Compact and Practical: The system is designed for external mounting on vehicles, offering a practical solution for real-world deployment. • Simulation-Guided Design: Used LightTools for optical design and Optisystem for communication link simulation to validate the design before implementation. • Significance and Application Value • Solves Critical Challenges: Provides a high-speed, secure, and EMI-free communication alternative to traditional RF in environments like military operations, petroleum facilities, and intelligent transportation systems. • 6G Potential: Serves as a practical reference for the development of VLC as a complementary technology in 6G networks. • Demonstrates Feasibility: Successfully proves the viability of using commercial LEDs and USRP platforms for building high-performance, medium-to-long-range optical communication systems. • This work represents a significant step forward in practical high-speed VLC system design, combining theoretical innovation with robust engineering to achieve state-of-the-art performance. Existing vehicular VLC systems suffer from limited bandwidth, short transmission distances, low data rates, and support only a narrow range of communication services. To address these issues, this paper proposes a vehicle-mounted high-speed LED visible light communication (VLC) system based on Universal Software Radio Peripheral (USRP). Leveraging 64QAM-OFDM digital modulation, an improved USRP X310 hardware platform, and a PC, we establish a novel architecture comprising digital baseband and optical transceiver modules. The baseband module eliminates traditional spectrum-shifting circuits and antennas, retaining only FPGA and ADC/DAC units. Audio/video files undergo 64QAM-OFDM modulation directly on the PC, with modulated signals output via DAC to a custom-designed wide-bandwidth LED transceiver. A broadband hardware equalization network based on a fourth-order RC bypass circuit was designed expands the 3dB bandwidth of high-power LEDs from 3 MHz to 120 MHz. Combined with automatic gain control (AGC), this achieves an optical transceiver with 12–15 W output power, >23 dB optical modulation signal-to-noise ratio (SNR), and stable receiver output voltage (1.2–2.0 V). The resulting compact system delivers low latency, high data rates, and high reliability. Under aligned optical path conditions, the system achieves >1 Mbit/s at 110 m (BER 0.49 × 10⁻⁵, delay 0.009-0.05s) and a peak rate of 500 Mbit/s at 10 m (BER 7.4 × 10⁻⁵), with an 11.5° transmit angle and a receiver field of view (FOV) of less than 18°. This work demonstrates the feasibility of high-power LED-based 64QAM-OFDM communication using USRP X310 for medium- to long-range vehicular links, providing a reference for intelligent transportation systems.

In this paper we propose a dual-hop mixed cooperative power line communication (PLC)-visible light communication (VLC) system, in which the VLC system is linked to the PLC backhaul link with the assistance of a decode and forward relay. The performance of the PLC link is evaluated under the effect of log-normal fading, and the link is presumed to be affected by both additive background and impulsive noises. The VLC link's channel characteristics are taken as a function of the position of the end users. The proposed study provides novel closed-form expressions of various statistics of the equivalent end-to-end signal-to-noise ratio of the considered system. Taking these derived entities into account, we also evaluate closed-form expressions of various performance metrics of the proposed system.

The exponential rise in wireless communication demands and allied applications have revitalized academia-industries to develop an efficient and potential solution. Furthermore, the high-pace increasing scarcity of radio spectrum has also alarmed researchers to achieve better Quality of Service (QoS) centric solution. To meet such demands Visible Light Communication (VLC) systems have gained global attention; however, up surging high rate, range and reliability (3R) needs demand better performance. Towards these goals, Multiple Input Multiple Output (MIMO) based VLC systems is an efficient approach; though its efficacy under Multiple Users (MU) conditions remains least explored. Enabling MIMO-MU based VLC can achieve 3R objectives effectively; however, factors like multipath attenuation, interferences and varied impairment-affects makes classical approached confined. The MIMO-MU VLC systems require robust error, noise or interference resilient transmission even under adverse conditions such as non-linear LED, multipath attenuation and interference. Towards these objectives, in this paper a highly robust MIMO-MU VLC system is developed that incorporates an augmented MIMO channel design and combined pre-coding and post equalization schemes. To alleviate major interference probability in MIMO-MU environment, proposed model incorporates time (delay)-multiplexing based data transmission followed by signal adaptive precoding and Volterra Kernel based Hybrid-equalizer. This approach enables interference and noise removal as well as LED non-linearity handling under MIMO-MU VLC communication. The use of a Volterra Kernel based Decision Feedback Equalization with both linear as well as non-linear equalization enables proposed VLC system to exhibit low Bit Error Rate with low modulation index and taps, that optimizes trade-off between performance as well as complexity.

The Visible Light Communication (VLC) has the potential to provide dense and fast connectivity at low cost. In this paper, we propose WSWDC, a novel VLC enabled wireless small-world data center. It employs VLC links to achieve a fully wireless data center network (DCN) across racks for the first time. The using of VLC links eliminates hierarchical switches and inter-rack cables, and thus reducing hardware investment, as well as maintenance cost. More precisely, to simplify the configuration and control operations, we propose three DCN design rationales: (1) fully-wireless, all inter-rack links are wireless; (2) easy-deployable, it is not necessary to change the existing infrastructure inside data center; (3) plug-and-play, no extra centralized control operations are required. Previous proposals, however, cannot achieve the three rationales simultaneously. To this end, we first use regular VLC links to interconnect racks as a regular grid DCN. To further exploiting the benefits of VLC links, a few random VLC links are carefully introduced to update the wireless grid DCN as a wireless small-world DCN. To avoid the potential interference among VLC links, we deploy VLC transceivers at different height on the top of each rack. In this way, VLC links would not interfere with others at each height level. Moreover, we design a greedy but efficient routing method for any pair of racks using their identifiers as inputs. Comprehensive evaluation results indicate that our WSWDC exhibits good network performance.

A new precoding scheme for spectral efficient optical OFDM systems

In visible light communication (VLC) systems, optical diversity improves system performance by utilizing multiple light sources at the transmitter. At the same time, orthogonal data transmission is used to distinguish overlapping optical signals at the photodetector. Based on these concepts, this paper suggests an innovative method to alleviate optical channel blockage by leveraging optical diversity and the orthogonality property; this is achieved by combining a modified version of frequency switching transmit diversity (FSTD) on the transmitter side with select best combining (SBC) on the receiver side in multiple input single output (MISO)-VLC systems. On this basis, the effectiveness of the suggested method is evaluated in free space optical across varying distances and different signal to noise ratio (SNR). The results indicate that the proposed approach outperforms conventional orthogonal techniques in MISO-VLC systems. Specifically, the proposed methodology achieved a bit error rate (BER) of 6.7 × 10−4 at a distance of 40 m with an SNR of 5 dB, whereas the FSTD technique recorded a BER of 1.5 × 10−3 under identical conditions. This superiority is attributed to integrating the SBC technique into the proposed approach, which allows for avoiding paths that lead to destructive interference with the optical signal.

Visible Light Communication (VLC) has emerged as an attractive alternative to radio frequency (RF) communication, due to cost-effectiveness and being license free. It has also proved its applicability in automotive applications, as an alternative and/or a complement to the traditional RF-based communications. We investigate the suitability of VLC in Intelligent Transportation Systems (ITS) and discuss its advantages in terms of safety enhancement and improved efficiency of the ITS. In this thesis, a VLC-based Vehicle-to-Vehicle (V2V) system in practical environments, considering both Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) paths are presented. The thesis investigates robust communication between a Light Emitting Diodes (LEDs) based VLC emitter and Photodiodes (PDs) based VLC receiver. For consideration of a V2V communication system, we consider transmitter on vehicle headlights and receivers on taillight making 2 _ 2 Multiple-Input-Multiple-Output (MIMO) communication link. A closed-form expression of the Channel Impulse Response (CIR) is derived and the effect of various channel parameters is analyzed. Optical-Orthogonal Frequency Division Multiplexing (O-OFDM) with adaptive modulation schemes is proposed for system improvement. Its performance is evaluated in terms of Inter Symbol Interference (ISI) mitigation, and data rate improvement. Moreover, the effect of sunlight on the V2V-VLC Two denoising schemes are proposed and evaluated as a solution to combat the effect of the solar irradiance on the VLC signal. Firstly, we use a differential receiver for denoising purposes followed by k-Nearest Neighbour (kNN) based adaptive _ltering algorithm, which is a supervised Machine Learning (MLE) technique. The shadowing effect is also studied. Moreover, an application of VLC in Foglet based ITS is described. The simulation validation of the VLC-based V2V system is performed under various environmental conditions and scenarios. Obtained results emphasize the suitability of VLC technology for automobile applications,.

This paper investigates the effect of light emitting diodes (LEDs) positioning and allocation in the channel analysis performance for an indoor intra-vehicle visible light communication (VLC) system. The MATLAB simulation results focus on the received power and the signal to noise ratio (SNR) within a sports utility vehicle. Furthermore, this work aims to validate by investigating two different scenarios, one utilizing two sources of power and the other using three sources of power with various locations, how LED’s spatial positioning affects the VLC system and the probability of error. Proving the demand for considering LEDs layout positioning while designing a VLC system.

Visible Light Communication (VLC) is a cutting-edge transmission technique where data is sent by modulating light intensity. Manchester On–Off Keying (OOK) is among the most used modulation techniques in VLC and is normed by IEEE 802.15.7 standard for wireless networks. Various Manchester decoder schemes are documented in the literature, often leveraging minimal two-level analog-to-digital converters followed by straightforward digital logic. These methods often compromise performance for simplicity. However, the VLC applications in fields like automotive and/or aerospace require the maximum performance in terms of bit error rate (BER) with respect to Signal-to-Noise Ratio (SNR), together with a real-time low-latency implementation. In this work, we introduce a high-performance Manchester decoder and detail its implementation in a Field Programmable Gate Array (FPGA). The decoder operates by acquiring a fully resolved signal (12-bit resolution) and by calculating the phase of the transmitted bit. Additionally, the proposed decoder achieves and maintains synchronization with the incoming signal, tolerating frequency shifts and jitter up to 1%. The Manchester decoder was tested in a VLC system with automotive-certified headlamps, realizing an IEEE 802.15.7-compliant link at 100 kb/s. The proposed decoder ensures a BER below 10−2 for SNR &gt; −12 dB and, compared to a standard decoder, achieves the same BER when the input signal has an SNR of 10 dB lower.

Modern hospitals are beginning to adopt E-HEALTH as efficient complements to the traditional healthcare services. To support the E-HEALTH services, a locatable, radiation-free and high-capacity communication system is urgently needed in hospitals. Power line communication (PLC) system can use the ubiquitous power line network to power the light-emitting diode (LED) lights while serving as the backbone network for the indoor visible light communication (VLC) systems naturally. In this paper, an integrated broadband power line and visible light communication systems with OFDM modulation is proposed for the indoor hospital applications. This gives a brand-new solution to replace the conventional wireless communication systems in hospitals.

Facing the current shortage of radio frequency spectrum resources, visible light communications (VLC) technology has been proposed to be a candidate technology in the sixth generation (6G), especially in the application of Intelligent Transportation Systems (ITS). And the propagation characteristics of VLC channel are critical for VLC system design and optimization. Furthermore, the impact of weather conditions on VLC channel cannot be ignored considering the vehicular VLC in ITS. In this paper, we experimentally investigate the impact of different weather types including fog and relative humidity (RH) on VLC in a laboratory atmospheric chamber. To simulate adverse weather conditions, we change the levels of fog density and water vapor introduced into the chamber, respectively. Then we measure the power attenuation and the bit error rate (BER) performance of VLC system under fog and RH conditions. We find that the VLC system will exhibit worse BER performance in the fog impaired channel than RH conditions. Besides, the results show that the bit errors will not happen until the attenuation reaches the threshold, i.e. attenuated by about 60% for both fog and RH conditions in our experiments. After that, the BER will deteriorate badly even up to 20%.

In this paper, a novel method is introduced to enhance the performance of vehicle-to-vehicle (V2V) visible light communication (VLC) by employing different transmitter (Tx) light-emitting diode (LED) array arrangements with different LED orientations. Improving the signal-to-noise ratio (SNR) is crucial for V2V VLC systems to provide long communication ranges. For this purpose, six transmitter configurations are proposed: single-LED transmitters, as well as 3 × 3 square-, single hexagonal-, octagonal-, 5 × 5 square-, and honeycomb hexagonal-shaped LED arrays. Indoor VLC studies using LED arrays offer a uniform SNR, while outdoor studies focus on optimizing the receiver side to enhance system performance. This paper optimizes system performance by increasing the SNR and communication range of V2V VLC systems by changing the geometry of the Tx LED array and LED orientations. A V2V VLC system using on–off keying (OOK) is modeled in MATLAB, and the SNR and bit error rate (BER) are simulated for different Tx configurations. Our results show that the honeycomb hexagonal transmitter design provides a 19% improvement in system performance with a spacing of 1 cm, and maintains a 16% improvement when the array size is reduced by a factor of 100, making it smaller than one of the smallest industrial headlight modules.

Inter-symbol interference (ISI) in visible light communication (VLC) systems has been considered as a major problem that seriously deteriorates system performance. A series of equalization algorithms have been widely investigated and utilized to eliminate ISI and improve the system performance. In this paper, we propose a novel algorithm called scalar modified cascaded multi-modulus algorithm (S-MCMMA) used in VLC system with PAM modulation. Furthermore, we experimentally demonstrate a red LED based PAM VLC system employing hardware pre-equalization technology and S-MCMMA equalization. A data rate of 525-Mbit/s for 8-PAM is successfully achieved in 1-m indoor free space transmission with the bit error rate (BER) below the 7 % forward error correction (FEC) limit of 3.8 × 10−3. Compared to the LMS equalization, the performance of S-MCMMA behaves quite similar (with a slight of advantage of S-MCMMA). However, the scheme is blind post-equalization without any training sequence aided thus higher bandwidth efficiency is achieved.

This paper analyzes the performance of a dual-hop hybrid radio frequency - visible light communications (VLCs) system. VLC exploits high frequencies for signal propagation for short-range and is highly susceptible to blockages. Hence, in this work, the sensitivity of the VLC toward the blockages is explored. This study examines outdoor-indoor communication for an urban scenario featuring an office environment. The VLC system is designed by considering multiple VLC access points serving the end users in the presence of human blockages. Selection combining is employed to select the access point which offers the maximum instantaneous signal-to-noise ratio at the user. To capture the outdoor scenario, path loss modeling is conducted to account for signal attenuation from outdoor to indoor spaces. The outdoor scenario is modeled using Nakagami-m fading channels while VLC is employed for the indoor scenario. System performance is assessed in closed-form expression for outage probability and the symbol error rate for binary phase shift keying and quadrature amplitude modulation. A deep learning-based approach detects the symbols by tracking dynamic changes in the channel. Simulation results corroborate the correctness of derived analytical expressions and reveal that blockages significantly impact both single and multiple LED based communication channels.

In this paper, we propose to apply the chaotic sequences to identify the users in high data rate visible light communication (VLC) system, and present a novel Logistics Iterative-chaotic-map-with-infinite-collapses Over Sampled Chaotic Map (L-I-OSCM) to generate the chaotic sequences. Specifically, we present a novel L-I-OSCM mapping scheme to improve the randomness of the chaotic sequences, with which the generated chaotic sequences have the property of having more complex and disordered phase space, being more sensitive to the initial value and having better randomness. Numerical analysis is performed to analyze and verify the better performance of L-I-OSCM scheme, and the property of chaotic sequences generated from different mapping patterns is compared. Since the chaotic sequences are noise-like and sensitive to the initial value, the access security is enhanced in L-I-OSCM chaos-based code division multiple access (C-CDMA) VLC system. Simulations are then provided to verify the effectiveness of the L-I-OSCM mapping C-CDMA VLC system, and the results demonstrate that both the bit error rate (BER) and the security performances are improved.