# Sensor-Based Solid Waste Handling Systems: A Survey
## 5 IoT-Enabled Solid Waste Management Systems
### Network Architecture
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ref.** & **Sensors** & **Radio Technology** & **Wireless Range** & **GPS** & **Energy Harvesting** \\ \hline
[41] & weight sensor:proximity sensor & Zigbee & Short & No & No \\
[42] & level sensor & Not Specified & Not Specified & No & No \\
[43] & Not Specified & Wi-Fi & Short & No & Yes \\
[44] & Ultrasonic sensor, load cell & GSM & long & Yes & No \\
[45] & Ultrasonic sensor & Wi-Fi & short & Yes & No \\
[46] & Ultrasonic sensor & GSM & long & No & No \\
[47] & IR sensor & RF & Short & No & No \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of IoT based solid waste handling systems. Figure 6: A generic IoT architecture for solid waste handling system. the degree of fullness of the trash bin. The network is deployed using low-power radio at the 2.4 GHz band. The collected data are sent to a remote server for the analysis and waste collection route optimization. A smart garbage bin for streets is presented in [46]. This system sends the sensor ID and geolocation of the almost-filled bins to authorized persons. However, the design of the nodes and other technical details were not presented clearly. In [47], an IR sensor-based smart waste management system using IoT is presented. The trash bins' filled levels are sent to an Intel Galileo Gen 2 board through RF modules. This work also presented a comparison with some of the existing systems. Most of the systems discussed here use short-range communication technologies such as Wi-Fi, Zigbee, RF, etc. These short-range communication technologies require repeaters to increase their wireless range and are not suited for the low power consumption nature of IoT nodes. The evolution of low power wide area networks (LPWAN) addresses the above limitations by introducing communication technologies that are capable of transmitting data in long-range with low power consumption. Table 5 shows the features of the most popular LPWAN protocols, such as LoRaWAN, Sigfox, and NB-IoT. The LoRa Alliance maintains LoRaWAN, which is an open specification that primarily serves as a network layer protocol for handling communication between LPWAN gateways and end-node devices [48]. Sigfox [49] is a software-based communication system that manages all networks and computes complexity in the cloud rather than on the devices themselves. When all of this is taken into account, connected devices' energy consumption and prices are reduced considerably. The Third Generation Partnership Project (3 GPP), which is responsible for the standardization of cellular systems, has launched NB-IoT [50] to address the needs of very low data rate devices that must connect to mobile networks and are often powered by batteries. Among the aforementioned LPWAN technologies, LoRaWAN is preferred for the deployment of IoT-based trash bin level monitoring systems because of the following features:  
* LoRaWAN is an open specification, whereas NB-IoT and Sigfox are proprietary network protocols. * LoRaWAN allows the establishment of private networks in which sensor nodes, gateways, and backhaul can be deployed by the user for a specific application. This is in contrast to NB-IoT and Sigfox, where a user needs to pay for connecting their sensor to the networks. * LoRaWAN supports firmware upgrade over the air (FUOTA) that enables the remote firmware update of the multiple devices deployed over the network. * LoRaWAN supports the Adaptive Data Rate mechanism for the optimization of power consumption, airtime, and data rates, whereas NB-IoT and Sigfox do not support this feature. Table 6 shows the summary of the state-of-art, LoRa-enabled. IoT-based trash bin level monitoring systems. Automated waste management systems using sensors to monitor bin state, TensorFlow-based object detection for garbage identification and categorization, and the LoRa communication protocol for long-range, low-power data transmission were presented in [51].