###### Abstract
In [34], an analytical daylight noise model based on a modified Blackbody radiation model is proposed to capture the effect of ambient light noise and conduct an in-depth study on the impact of daylight on system performance. This study also proposes a selective combining receiver to improve the BER at the expense of a slight increase in the cost and complexity of the receiver. In [35], the replacement of the traditional photodiode receiver with an imaging receiver is analyzed, showing that this replacement leads to improved performance with an increased SNR. In [36], an indoor cellular VLC system is proposed with hexagonal LED arrays to enhance the BER. In [37], an indoor VLC system is analyzed. The system has sixteen LEDs on the ceiling that are used as transmitters. The paper aims to improve SNR uniformity throughout the room without increasing the number of transmitters on the ceiling. Instead, it considers altering the lamp arrangement and evaluates the uniformity of light and SNR distribution throughout the room. In this paper, a V2V VLC system using on-off keying (OOK) is modeled in MATLAB, and the SNR and BER are simulated for different Tx configurations. The Pulse Position Modulation (PPM) and Non-Return-to-Zero (NRZ) modulation techniques are complex modulation methods preferred in certain applications [38; 39]. PPM is used especially in applications requiring energy efficiency and low noise sensitivity, while NRZ offers the advantage of low cost in data transmission. However, the reason we preferred OOK modulation in this study is the simplicity, applicability, and widespread use of this modulation method in LED-based communication systems. OOK modulation offers the advantages of low complexity and easy implementation, making it ideal for performing a basic performance analysis of different geometric LED arrays. Therefore, PPM and NRZ modulations were not needed in our study. Unlike most V2V VLC studies that are focused on the receiver side, by proposing six different transmitter LED array configurations to increase the SNR, this paper aims to optimize the transmitter side to improve the SNR of a V2V VLC system using OOK. The use of various arrangements of LED arrays is considered in the literature for indoor VLC to achieve light and SNR uniformity. However, this paper evaluates the enhancement in the SNR and, hence, the communication range that LED array transmitters of various geometries can achieve. In addition, we adjust the orientations of the LEDs to ensure that every configuration illuminates approximately the same area. This approach allows us to exploit the smaller FOV of each LED in the array transmitters to increase the SNR and, hence, the communication range. Our results show that the LED arrays outperform single-LED transmitters, offering a higher SNR due to the smaller FOV of their elements. Additionally, it is demonstrated that different geometries of arrays achieve varying levels of improvement. In particular, the honeycomb hexagonal array provides the furthest communication distance, achieving a 19% increase compared to the single-LED transmitter. The remainder of this paper is organized as follows: Section 2 presents the theoretical background of calculating the SNR. Section 3 presents the geometry of the proposed V2V communication system, MATLAB [40] simulation parameters, and modeling of the square-, single hexagonal-, octagonal-, and honeycomb hexagonal-shaped LED array transmitter (Tx) configurations. Section 4 compares the irradiance distributions of the proposed LED arrays at a 1 m distance. Section 5 evaluates the SNR performance across different design parameters and compares the SNR results of the proposed transmitters. Section 6 presents a discussion, and Section 7 outlines the theoretical and practical implications of the study. Finally, Section 8 concludes the paper.