In this paper, the application of orthogonal frequency division multiplexing (OFDM) over an indoor wireless optical channel is investigated. Previous studies have demonstrated that it can be characterised as almost stationary but with a severe penalty induced by multipath propagation. It is also highly dependent on the spatial distribution of emitters and receivers. OFDM systems have been chosen owing to their capability of supporting high data rates without channel equalisation. They also mitigate the effect of quality fluctuations of the channel induced when the spatial distribution of emitters and receivers varies. We present several results about system performance. Finally, an adaptive OFDM system is proposed to increase data throughput. The obtained results show that a significant throughput is attained over noisy wireless optical channels.

A modified Monte Carlo algorithm for the calculation of the impulse response on infrared wireless indoor channels is presented. As is well known, the characteristics of the room where the IR diffuse channel is implemented can lead to problems in communication, such as a multipath penalty on the maximum baud rate or hidden-station situations. Classical algorithms require large computational effort to calculate the impulse response in an ordinary-size room. Monte Carlo offers the possibility of validating the assumptions made for these classic algorithms (basically, the Lambertian nature of all reflections) with a computational complexity that is determined by the accuracy desired by the user. We have developed a mixed ray-tracing-deterministic algorithm that assures that each ray contributes to the final channel response function as many times as it rebounds with an obstacle. It increases dramatically the number of contributions and reduces, to the same extent, the time required for an accurate simulation. Extensive simulation results are presented and are compared with those of other simulation methods. We demonstrate that the method presented here is much faster than Monte Carlo classical simulation schemes. It can be used as a method of simulation in itself or as a validation algorithm for other comparative studies of pulse broadening.

Recycling behavior is an issue that affects the sustainability of many seasonal destinations. The EU promotes projects such as the UrbanWaste that try to study how to avoid the deplorable consequences on cities of this situation. This project has implemented a gamified application, named WasteApp in several European cities, in order to promote the recycling behavior of tourists. This study aimed to verify if the application can be a successful tool to foster recycling and to improve tourism destination reputation. The results show that tourist satisfaction will be influenced directly by the perceived usefulness of the application, and perceived usefulness by the perceived ease of use, but the expectations of the prizes can be counterproductive if they are not perceived as useful for the promoted behavior. Likewise, the satisfaction of the user will influence the recycling behavior, which at the same time improves the reputation of the destination. Besides, the initiative will be visible through word of mouth that is generated from the perceived usefulness, the user’s satisfaction, and the recycling behavior itself. That is, according to this study a gamified application can contribute to the recycling behavior of tourists and improve the image of the destination that adopts it.

The authors propose an adaptive orthogonal frequency division multiplexing (OFDM) system for communications over the indoor wireless diffuse optical channel. This channel can be characterised as short-term stationary, with severe attenuation and multipath-induced penalty, and high dependence on the space distribution of emitters and receivers. We have chosen OFDM systems because of their capability of supporting high data rates without channel equalisation. They also mitigate the quality of service fluctuations induced when space distribution of emitters and receivers varies. The performance of the new proposed scheme is compared with that of an adaptive system described in a previous work. The obtained results show that a significant increase of the system throughput is attained over noisy wireless optical channels.