# Energy Efficiency of IoT Networks for Environmental Parameters of Bulgarian Cities  
[PERSON]  
1 Faculty of Technics and Technologies, Trakia University, 38 Graf Ignatiev Str.,  
Yambol, 8602 Stara Zagora, Bulgaria; [EMAIL_ADDRESS] (A.T.);  
[EMAIL_ADDRESS] (V.S.) [PERSON]  
2 Department of Automatics and Mechatronics, Ruse University, \"[PERSON]\" Ruse 8 Studentska Str.,  
7017 Ruse, Bulgaria; [EMAIL_ADDRESS] (Correspondence: [EMAIL_ADDRESS] 2  
in the city in order to reduce noise and the amount of harmful substances. In the same way, recommendations can be generated for production enterprises in the city to reduce harmful emissions and waste products resulting from the production they perform. The ultimate goal to be achieved is to create healthy living conditions for the population and protect the environment by developing and implementing an integrated approach and measures to avoid air and water pollutants and high noise levels by preventing or reducing these harmful effects. In recent years, measures have been adopted in Bulgaria to measure the levels of harmful emissions, noise and pollutants from transport and industrial enterprises in urban environments. These measures are in line with the requirements of the European Union to ensure a healthy living environment in cities. The potential applications of IoT in this regard are diverse. The European Commission's IoT documents include the so-called smart city, defined as \"a place where traditional networks and services become more efficient by using digital and telecommunications technologies for the benefit of residents and businesses\" [3]. Updating the map for noise in settlements in Bulgaria is related to the fulfillment of the requirements of the Environmental Noise Protection Act (EPAA) (Promulgated, SG No. 74 of 13 September 2005) and Directive 2002/49/EC for the assessment and management of environmental noise. According to these requirements, it is the duty of every agglomeration with a population of over 100,000 inhabitants to update its noise map. In the larger cities of the Republic of Bulgaria such measures to ensure low levels of harmful emissions, reduce noise levels, and ensure comfort in urban environments have been taken [4]. The measures are also supported by companies offering mobile services [5; 6]. The following are provided [5]: intelligent parking systems, which show drivers the nearest free parking space and navigate them to it; intelligent lighting, providing greater security for citizens as well as saving on electricity costs for municipalities; air quality control; effective management of garbage containers; remote and intelligent metering of water meters, electricity meters and other measuring devices for households. Measurements are based on automatic specialized stations, as well as by measuring with portable measuring instruments. The trend is to expand networks for automatic measurement and storage. For this purpose, it is necessary to select the appropriate technology for the wireless transmission of sensor data. A review of the available literature sources [1; 4; 6] shows that in Bulgaria there is a need to create new and expand existing wireless sensor networks to measure the levels of pollutants in the environment. There is little research on the energy efficiency of this type of network. Building modern systems based on IoT is associated with a number of challenges. One of the most important among them is the need for wireless technology, which will serve to build connectivity between the individual components of a new technology. There are various standards for wireless communication. Several of them are widely used and applicable to objects and devices with extremely low power. They can be IP-compatible or non-IP-compliant. Most of the wireless standards applicable to low-power devices are characterized by having a short range [7; 8]. These standards are suitable for use in the construction of WSN, of course, taking into account their advantages and limitations.