
A legacy 2G celullar system monitors the fill levels of waste containers in Lisbon. With a new LoRa system, this waste management network would be integrated with networks of other services like fire departments or healthcare.
Waste Disposal Management and Container Fill Level Tracking

Underground containers were equipped with ultrasound waste-level measurement sensors from IoTsens. The sensors have a reading range of up to seven meters and cost 300 euros.
Testing Sensor Connection Capabilities of LoRaWAN in the Most Challenging Use Case
IoTsens sensors were selected for the higher reading range that is required in unterground containers. Experiments with probes revealed that the connection to the LoRa Network from underground containers is more difficult as the signals have to pass through the surrounding steel construction and pavement.
The metal construction and surrounding pavement of underground waste containers in Lisbon can disrupt the transmission of information from the sensors to the LoRa gateway.
Testing Sensor Connection Capabilities of LoRaWAN in the Most Challenging Use Case
IoTsens sensors were selected for the higher reading range that is required in unterground containers. Experiments with probes revealed that the connection to the LoRa Network from underground containers is more difficult as the signals have to pass through the surrounding steel construction and pavement.
The metal construction and surrounding pavement of underground waste containers in Lisbon can disrupt the transmission of information from the sensors to the LoRa gateway.

Underground containers were equipped with ultrasound waste-level measurement sensors from IoTsens. The sensors have a reading range of up to seven meters and cost 300 euros.

Replacing the 2G Legacy System
Lisbon has a system for garbage truck route optimization and contrainer fill level tracking for both underground and regular waste containers. This system is based on 2G cellular technology. Waste management was regarded as the most challenging use case to implement LoRa technology and selected for network implementation testing. Sensor placement on the underground containers re-used existing drill holes from previous vendors.
Replacing the 2G Legacy System
Lisbon has a system for garbage truck route optimization and contrainer fill level tracking for both underground and regular waste containers. This system is based on 2G cellular technology. Waste management was regarded as the most challenging use case to implement LoRa technology and selected for network implementation testing. Sensor placement on the underground containers re-used existing drill holes from previous vendors.


Striving to Implement an Easy to Install Solution
The attenuation of the surrounding metal construction and pavement is so large that the current service provider had to modify the containers. Holes for external antennas were drilled to enable signal transmission from the sensors (black sensor, top left). These kind of adaptations disable the watertightness of the containers. The future LoRa solution is planned to avoid requiring any further modifications. Transition between vendors is expected to simplify based on the implementation of a common network standard.
Striving to Implement an Easy to Install Solution
The attenuation of the surrounding metal construction and pavement is so large that the current service provider had to modify the containers. Holes for external antennas were drilled to enable signal transmission from the sensors (black sensor, top left). These kind of adaptations disable the watertightness of the containers. The future LoRa solution is planned to avoid requiring any further modifications. Transition between vendors is expected to simplify based on the implementation of a common network standard.


The Cyclea (blue) and Iglô (green) are the containers used in Lisbon for recycleable waste and glass. Ultrasound sensors were deployed on the inside, measuring the distance between the top of the container and the waste, indicating the fill level.
Simulating Government Procurement for Sensors
Finding the Ideal Sensor for Each Individual Use Case
Different sensors were purchased by the research group to simulate the process of government procurement. The sensors for the overground use case do not require such a high reading range as those chosen for the underground containers. Since a reading range of less than two meters is required based on the container height, Dingtek702 sensors were selected.
Simulating Government Procurement for Sensors
Finding the Ideal Sensor for Each Individual Use Case
Different sensors were purchased by the research group to simulate the process of government procurement. The sensors for the overground use case do not require such a high reading range as those chosen for the underground containers. Since a reading range of less than two meters is required based on the container height, Dingtek702 sensors were selected.

The Cyclea (blue) and Iglô (green) are the containers used in Lisbon for recycleable waste and glass. Ultrasound sensors were deployed on the inside, measuring the distance between the top of the container and the waste, indicating the fill level.

Overground Container Sensors
Surface-level containers were equipped with Dingtek702 ultrasound waste-level measurement sensors. These sensors have a reading range of up to four meters and cost 70 euros. All deployed waste sensors in both testing scenarios were attached using metal structural support. Even though metal has a negative effect on the transmission strength and thus signal quality from the sensor to the LoRa gateway, the waste management environment exposes the sensors to external forces during waste pick-up for example. Robust structural support is the only practical solution but also causes an inevitable impact on the signal quallity.
Overground Container Sensors
Surface-level containers were equipped with Dingtek702 ultrasound waste-level measurement sensors. These sensors have a reading range of up to four meters and cost 70 euros. All deployed waste sensors in both testing scenarios were attached using metal structural support. Even though metal has a negative effect on the transmission strength and thus signal quality from the sensor to the LoRa gateway, the waste management environment exposes the sensors to external forces during waste pick-up for example. Robust structural support is the only practical solution but also causes an inevitable impact on the signal quallity.


Sensor Mounting
Dingtek702 Sensors were mounted in the containers for recycleable waste and for glass waste. Similar to the deployment of the IoTsens sensors, the research group attached the sensors in the same location in which the previous vendor had deployed their own sensors.
Sensor Mounting
Dingtek702 Sensors were mounted in the containers for recycleable waste and for glass waste. Similar to the deployment of the IoTsens sensors, the research group attached the sensors in the same location in which the previous vendor had deployed their own sensors.

Field Trial for Sensor and LoRa Communication Implementation

Sensors were attached to underground containers (RU) at the three locations of ISEL, Spacio Shopping and Belém in Lisbon to test the capabilites of LoRa technology in short (100m), medium (1km), and long-range (5km) communications respectively.
Limit Testing for LoRaWAN in Lisbon
LoRaWAN technology and LoRa gateways were chosen because of their low energy consumption. In field trials, the research from FIT/ISEL aimed to test the quality and limitations of the communication from the sensors to gateways over various distances.
Limit Testing for LoRaWAN in Lisbon
LoRaWAN technology and LoRa gateways were chosen because of their low energy consumption. In field trials, the research from FIT/ISEL aimed to test the quality and limitations of the communication from the sensors to gateways over various distances.

Sensors were attached to underground containers (RU) at the three locations of ISEL, Spacio Shopping and Belém in Lisbon to test the capabilites of LoRa technology in short (100m), medium (1km), and long-range (5km) communications respectively.

Verifying the Capacity of LoRa in Challenging Use Cases
Two LoRa gateways were deployed in Lisbon to test the signal strength received from the installed Dingtek702 and IoTsens sensors. The gateways were sold by different manufacturers. One gateway was mounted at ISEL and one at Amoreiras, at altitudes of 100 and 175 meters above sea level respectively. Sensors were installed at distances of 100 meters, 1km and 5km from the gateways. Expectations prior to the trials were that communication at short range would most likely work, long range was unlikely to work, and the capacity of medium range was uncertain.
Verifying the Capacity of LoRa in Challenging Use Cases
Two LoRa gateways were deployed in Lisbon to test the signal strength received from the installed Dingtek702 and IoTsens sensors. The gateways were sold by different manufacturers. One gateway was mounted at ISEL and one at Amoreiras, at altitudes of 100 and 175 meters above sea level respectively. Sensors were installed at distances of 100 meters, 1km and 5km from the gateways. Expectations prior to the trials were that communication at short range would most likely work, long range was unlikely to work, and the capacity of medium range was uncertain.


Radio Coverage
The research aimed to determine necessary radio coverage of the network for both surface-level and underground waste containers and the number of gateways that would have to be deployed for a city-wide LoRa-coverage based on the test results. As waste management was regarded as the most difficult use case based on the metallic surrounding and structural support, other network applications of different public services with fewer disruptions would also be able to communicate with the gateways.
Radio Coverage
The research aimed to determine necessary radio coverage of the network for both surface-level and underground waste containers and the number of gateways that would have to be deployed for a city-wide LoRa-coverage based on the test results. As waste management was regarded as the most difficult use case based on the metallic surrounding and structural support, other network applications of different public services with fewer disruptions would also be able to communicate with the gateways.

Research Results Guide Public Tender Rules in Smart Lisbon Network Establishment

Signals transmitted from the underground container at Spacio Shopping (medium range, 1 km) to the gateway at ISEL indicate a decreasing reading distance based on filling level, ADR (Adaptive Data Rate) optimizing transmission rate by changing to different spread factors (SF10 to SF12) over time.
LoRa Transmission Successfully Received from Underground Containers at Short and Medium Distance
The Gateways at ISEL received transmission from both sensors in underground containers deployed within short and medium distance. The gateway at Amoreiras did not receive any transmission from the sensors at a long distance. Midway through the trial period, the gateway at ISEL malfunctioned and had to be replaced.
The readings indicate a reliable transmission of data from the sensor in the underground container that corresponds with filling level increasing as indicated by the decrease in distance between the sensor and the waste until this was reset by emptying the container. The high frequency of the readings at spread factor 12 indicates frequent messages being sent from the sensor to the gateway.
The changing spread factor indicates an automatic optimization of the relationship between the signal transmission rate, duty cycle and energy consumption. Lower spreading factors require low amounts of attenuation, however the attenuation caused by the metal surroundings of the underground containers is high, requiring a higher spreading factor.
LoRa Transmission Successfully Received from Underground Containers at Short and Medium Distance
The Gateways at ISEL received transmission from both sensors in underground containers deployed within short and medium distance. The gateway at Amoreiras did not receive any transmission from the sensors at a long distance. Midway through the trial period, the gateway at ISEL malfunctioned and had to be replaced.
The readings indicate a reliable transmission of data from the sensor in the underground container that corresponds with filling level increasing as indicated by the decrease in distance between the sensor and the waste until this was reset by emptying the container. The high frequency of the readings at spread factor 12 indicates frequent messages being sent from the sensor to the gateway.
The changing spread factor indicates an automatic optimization of the relationship between the signal transmission rate, duty cycle and energy consumption. Lower spreading factors require low amounts of attenuation, however the attenuation caused by the metal surroundings of the underground containers is high, requiring a higher spreading factor.

Signals transmitted from the underground container at Spacio Shopping (medium range, 1 km) to the gateway at ISEL indicate a decreasing reading distance based on filling level, ADR (Adaptive Data Rate) optimizing transmission rate by changing to different spread factors (SF10 to SF12) over time.

LoRa probes were used to determine the signal interference from the container material on both overground and underground containers.
Research Insights Guide Lisbon Towards an Open LoRa Network
Based on the research by FIT/ISEL, guidelines for public tender rules and the eventual implementation of a city-wide LoRa network were developed. The minimum guidelines finalized by FIT/ISEL were as follows:
- Implementation of at least 15 LoRa-gateways
- 90 % surface radio coverage at an RSSI (received signal strength indicator) above 115 dBm and a Signal-to-Noise Ratio of 5 dB
- 24 Messages sent per day and device.
- Network Service-Level-Agreements
- Provision of an open network server
Implementation and service provision based on these guidelines began in 2021 and is currently being deployed.
LoRa probes were able to record the transmission interference caused by the material of both overground and underground waste containers as an important metric to define network requirements. It was found that the material of the overground containers had no significant impact on transmission, yielding similar RSSI values on the inside and outside of the container. On underground containers, the RSSI measured on the outside was around 20 dBm higher than on the inside, indicating a significant impact of antenna placement for these containers.
Research Insights Guide Lisbon Towards an Open LoRa Network
Based on the research by FIT/ISEL, guidelines for public tender rules and the eventual implementation of a city-wide LoRa network were developed. The minimum guidelines finalized by FIT/ISEL were as follows:
- Implementation of at least 15 LoRa-gateways
- 90 % surface radio coverage at an RSSI (received signal strength indicator) above 115 dBm and a Signal-to-Noise Ratio of 5 dB
- 24 Messages sent per day and device.
- Network Service-Level-Agreements
- Provision of an open network server
Implementation and service provision based on these guidelines began in 2021 and is currently being deployed.
LoRa probes were able to record the transmission interference caused by the material of both overground and underground waste containers as an important metric to define network requirements. It was found that the material of the overground containers had no significant impact on transmission, yielding similar RSSI values on the inside and outside of the container. On underground containers, the RSSI measured on the outside was around 20 dBm higher than on the inside, indicating a significant impact of antenna placement for these containers.

LoRa probes were used to determine the signal interference from the container material on both overground and underground containers.