Software Defined Visible Light Communication Demonstrator(SILENCE)

 

Aware of the impact that standard based systems can have in the introduction and commercialization of new solutions, a team in CTTC has developed one of the world’s first prototype using VLC technology based on the standard IEEE 802.15.7. This system is conceived as a prototyping platform useful to investigate novel communication algorithms or to improve the performance of a VLC system and foster the creation of new standard compliant VLC applications. 

The development of this platform has been done using the concept of Software Defined Radio (SDR), where the signal processing functions are performed in a general purpose processor (GPP), while the  signal acquisition and conversion (A/D, D/A) are performed in a programmable hardware. 

 The use of the SDR concept is aligned with the aforementioned objectives because it provides the system with a high degree of flexibility and modularity regarding a pure hardware (HW) based implementation. This feature allows the platform to evolve and cope with future enhancements without requiring a long development time. Furthermore, this software based solution provides a user friendly environment for researchers, accelerating the transition from simulation to demonstration.

Under the SDR approach, the architecture of the demonstrator is divided into two subsystems: the hardware and the software subsystem. The hardware subsystem is formed by the opto-electronic devices, the analog circuitry needed to control and to condition the signal originated or directed to the opto-electronic devices and Universal Series Radio Peripheral (USRP) platforms.

 Silence block diagram

The software subsystem is composed by the personal computers (PC), where the signal processing is run by the help of a custom object-oriented framework based on a collection of open source libraries. The following figure illustrates the concept of software define radio visible light system (SDR-VLC) used in the development of our demonstrator.