###### Abstract  
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 \(\times\) 3 square-, single hexagonal-, octagonal-, 5 \(\times\) 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. vehicle-to-vehicle communication; visible light communication; signal-to-noise ratio; bit error rate; maximum communication range; light-emitting diode arrays; field of view +
Footnote †: journal: Sensor and Actuator Networks  
urban canyons and tunnels [7; 22]. Moreover, V2V VLC offers the potential for high data rate transmission and low latency, which are crucial for real-time applications in intelligent transportation systems (ITS) [8; 23; 24]. Technological advancements in V2V VLC are drawing significant attention within the automotive industry. Numerous studies in the literature [25; 26; 27] have explored the application of VLC utilizing photodetectors instead of camera systems for automotive purposes. These studies highlight the potential of leveraging existing lighting infrastructure for communication. Additionally, this technology allows automotive companies to integrate V2V communication with minimal alterations into existing vehicle designs, primarily through minor modifications to current lighting systems [28; 29]. The deployment of LEDs in vehicle headlights and taillights for communication purposes is particularly promising, as it represents a potential technology to enhance vehicle safety. However, increasing the signal-to-noise ratio (SNR) to provide a long communication range in a V2V VLC system is a challenge. To solve this problem, many studies have been conducted in the literature, with most studies focusing on improving V2V VLC systems by optimizing the receiver (Rx) side. In [30], the misalignment effect in V2V VLC systems is evaluated with an experimental demonstration of a 75 m link. This paper also confirms that the optical filters and narrow field of view (FOV) obtained with optical lenses can significantly optimize a VLC receiver. In [31], a novel concept that uses LED current overdriving is introduced to increase the instantaneous optical irradiance and, in turn, the communication range. In [32], it is discussed that the high mobility of vehicles necessitates an adaptive physical layer (PHY) design for reliable and rate-optimal communication. This paper proposes a novel low-complexity, location-aware adaptive PHY design that attains reliable, rate-optimal vehicular VLC without a feedback channel. In [33], the achievable transmission distance for a targeted data rate while satisfying a bit error rate (BER) value is determined for different weather conditions. This study presents numerical results for clear, rainy, and foggy weather conditions and quantifies degradation from adverse weather conditions.