Özet:

Due to the rapid demand for advanced technologies and information, the radio frequency (RF) bands assigned to wireless mobile communications are rapidly filling, resulting in the approach to the upper boundaries of the RF frequency band. Therefore, it is clear that working on higher frequency bands beyond the potential frequency bands to be determined for the 5th generation (5G) systems will become extremely difficult or impossible. In this case RF technology may be an alternative and it requires research and development work for the development of new optical-based communication technologies parallel to this technology. The most suitable solution to this problem is the visible light communication (VLC), which has a very broad and unregulated frequency band, which stands out as an interesting technology and is continuing to work on intensive research and development. Because a realistic channel model is not achieved near all of the recent studies in the VLC field, only ideal collective white Gauss noise (AWGN) channels have been used. In this context, it is of great importance to identify the actual model of the channel environment that a VLC system will use and to determine the error success of communication through this channel. The main objective of this study is to introduce researchers focused on the subject of wireless mobile communications with the details of this current and interesting field and to present the design of a new and original VLC system that can access high data speeds for optical multi-input multi-output (MIMO) communication-based straight frequency divided reproduction (OFDM). The recommended technique for an optical MIMO system with four-light diot (LED) and four-photo detectors (PD) is shown to provide the highest failure success compared to other MIMO-VLC techniques by examining the failure success through real optical channels modeled with the help of the Zemax software. Rapid development in technology and increasing necessity to reach information instantaneously, drives the radio frequency (RF) band to a bottleneck. It can be seen that, we are gradually approaching to the upper limits of the band at both network access and backhaul levels. Operating beyond that upper limit would be so difficult or may be unfeasible for 5th generation (5G) mobile communication systems. In such case, it is necessary to develop optics based alternative telecommunication systems to RF technology. Visible light communications (VLC) could be the most appropriate and appealing solution for researchers due to its unregulated and very wide frequency band. Yet, there is no appropriate VLC channel model in the literature, only ideal and additive white Gaussian noise (AWGN) channels are assumed in the recent papers. In this context, determination of the real VLC channel models would play a vital role on the bit error rate performance of the communication systems. The main objective of this tutorial paper is, to introduce this unique and interesting topic to the researchers and offer detailed information on a novel VLC system based on multiple-input-multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM). Besides, proposed 4 LEDs and 4 photodiodes (PD) containing MIMO system is analyzed by computer simulations in the presence of real optical channels created by an optical design software Zemax. It has been shown that this scheme provides the best BER performance compared to the other MIMO-VLC systems.

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