## 1 Introduction  
Nowadays, there is a trend in replacing fluorescent and halogen lamps, both indoor and outdoor, by LED-based ones, which are energy efficient and offer extended life cycles and high switching speed. This change also affects street, traffic and car lights (hazard, tail, sidelights, and so forth), opening the opportunity of deploying new communication systems over the fundamentals of Optical Camera Communications (OCC) [1] for a wide range of applications, e.g., in smart cities or V2X networks. OCC is a specific kind of VLC-based technique [2] that uses LED-based devices (such as lamps, or screens) for transmitting data, and image sensors for receiving the signals. OCC deployment is low cost, offers immunity to Radio Frequency (RF) interference, and takes advantage of the fast insertion of deviceswith embedded cameras in day-to-day activities. VLC techniques, including OCC, solve critical issues of the current RF telecommunication implementations: the spectrum saturation and the interferences from widespread RF systems. Due to the use of visible light signals and photoreceivers, there are other interfering sources that should be taken into account during channel characterization and link design stages. Weather conditions, the possible image distortions due to both optical turbulence [3; 4] and lens aberration [5], the solar radiation interference, and other light sources constitute the main problems that outdoor systems need to consider. Some research works modeling the impact of climate conditions on the system's performance have been published. In this sense, the effect of snowfall was simulated in [6], showing that the attenuation and the time variation of the received signal cannot be ignored and depends on the size distribution of the snowflakes due to Fresnel diffraction. In [7], the influence of rainfall in VLC links was analyzed. This work established that the optical transmitted signal is scattered when hits a raindrop, so the received power diminished according to the rain rate (number and size of raindrops). In addition, the attenuation introduced by fog in Free-space optical (FSO) communications was studied in [8], showing that it can be predicted according to visibility scenarios without using heavy computer codes. These channel modeling research works were based on photodiode-based receivers. Nevertheless, in an attempt of characterizing multi-element receivers, such as cameras, [PERSON] et al. [9] studied the effect of distance using a photodiode array and defined the critical distance where the LED generates an image of one pixel only. Moreover, the viewing-angle dependency was characterized in [10] in terms of the Signal-to-Noise ratio (SNR). The study of self-interference in OCC as a performance degradation factor has been addressed in [10; 11]. However, the chromatic effect has not been discussed. In this topic, the characterization of vehicle-to-traffic-light communications assuming that the link is affected only by background solar radiation (for yellow, red and green) and artificial light sources (lighting and advertising) excluding close emitters from the same system was presented in [12]. Some practical issues related to the use of multi-LED transmitters with chromatic modulation were addressed by [13] for OCC, but only the viewing angle distortion was used as a critical parameter. Finally, [PERSON] and [PERSON] [14] presented the effect of mobility on the performance of these systems using photodiodes as receivers. It was shown that the system performance depends on the speed; if the users move faster, the packet loss increases. The application of the Internet of Things (IoT) over a heterogeneous network has become a current trend [15]. This novel network ecosystem uses a large variety of transmission data rate. For slow data rate applications, such as in wireless sensor networks (WSN) which require transferring minimum amounts of data (for example temperature, pressure, humidity, or presence flags), the use of preexisting cameras-based infrastructure is a possible solution.