# Streetlight Control System Based on Wireless Communication over DALI Protocol
## 2 Related Works  
Many works deal with the smart control of outdoor lighting systems to solve specific problems. On the one hand, they do so by using new technologies such as LED technology. On the other hand, the most innovative approach may be to use a remote control based on wireless communication and on control over smart ballasts. Several scientific studies have taken advantage of WSNs for public lighting systems. A ZigBee-based wireless control system is presented in [12]. Its aim is to overcome the disadvantages of a control group base by designing a public lighting control system that is able to control each luminaire individually. This study considers communication systems such as those based on power line communication (PLC) and ZigBee, and describe and compare their features. Finally, ZigBee is chosen due to the inconveniences of PLC, such as the price of the devices and the lack of communication when a short-circuit problem appears. Its system allows the user to control and monitor the state of the lighting; however, energy efficiency is not taken into account. Just maintenance and the removal of cables from the streets are taken into account to protect individuals from electric shocks.  
Another more complex example of the application of WSNs to public lighting is found in [13]. A system is developed that consists of sensor nodes placed at each side of the street, with a receiver node at the main transformation station to which each luminaire belongs. Information from the receiver nodes is sent to the control center through GPRS. The system also has individual or group regulation, which saves up to 60% in energy consumption. A significant breakthrough of these systems is the combined use of identification addresses for the individual nodes, together with a geographic information system (GIS) that enables the graphic viewing of the location of any individual node. As a result, it is possible to know the location and state of each lamp. A simple but effective routing protocol is proposed in a later study [14] that makes it unnecessary to take the network topology into account, which is convenient due to the characteristics of public lighting.  
Another proposal [15] lists the main characteristics of a WSN that may be used in a control system for public lighting. Among these characteristics, we find the ability to manage common operations in public lighting, such as turning off/on or regulation (dimming) and network functions such as neighbor discovery, pairing, and network formation. 6 LoWPAN(tm) is used instead of ZigBee due to the disadvantages of the latter's routing protocol (high end-to-end delay, low packet delivery ratio) and the easy adaptation of 6 LoWPAN, which does not define the routing protocols for a specific system.  
Other more current examples of the application of WSN to public lighting can be found in [16], in which the authors analyze the use of solar energy and propose a stand-alone streetlight system using a ZigBee network supplied by solar PV panels. Using part of the previous work, in [17], the authors present a fully controlled street lighting \"_isle_\" with a WIMAX connection. Lastly, we point out [18], which presents a streetlight control system based on wireless communication using LED technology. However, the authors do not use any standard protocol to control the lamps.  
Other perspectives have been considered for the use of the DALI protocol in public lighting and its integration with WSNs. In fact, the NumeLiTe Project [19; 20] used the DALI protocol for street lighting applications, but the manufacturers did not take this into account and the project was finally used just for indoor lighting and not for public lighting systems. Another work developed a DALI-protocol-based electronic ballast for sending commands through radio waves with a ZigBee module [21].