How does LoRa achieve positioning? LoRa uses Time Difference of Arrival (TDOA) to achieve geographical positioning.
A technology based on LORA positioning, including an information transmission system, a network transmission system and an information processing system, characterized in that the output end of the information transmission system is connected to the input end of the network transmission system, and the output end of the network transmission system Connected to the input end of the information processing system, the information transmission system includes Beacon beacon, GPS satellite, base signal tower, LORA tag and LORA area network, the input end of the Beacon beacon, GPS satellite and base signal tower The input end of the LORA tag is connected to the input end of the LORA tag. The output end of the LORA tag is connected to the input end of the LORA area network. The network transmission system includes a LORA gateway, a network connection and a wide area network. The output end of the LORA gateway is connected to the input end of the network connection. end connection. The arrangement of Beacon beacons, GPS satellites and base signal towers in the present invention makes the system more accurate in positioning personnel and has a wider scope of application, thereby ensuring the accuracy of personnel positioning.
1. LoRa positioning principle
To understand how LoRa positioning works, it is necessary to look at the data transmission steps from the end node to the server. The premise of LoRa positioning is that all base stations or gateways share a common time base, which is very important.
When any LoRaWAN terminal device sends a data packet, it will be received by all gateways within the network range, and each packet will be reported to the network server. All gateways are the same, they receive signals at all data rates on all channels all the time. This means there is no overhead on LoRa end devices as they do not need to scan and connect to a specific gateway. The sensor simply wakes up, sends a packet, and all gateways within the network range can receive it.
All gateways send the same packets they receive to the network server, capturing high-precision arrival times using specialized hardware and software built into the latest generation of gateways. Algorithms on the network server side compare arrival time, signal strength, signal-to-noise ratio and other parameters to calculate the most likely location of the end node. In the future, we look forward to hybrid data fusion technology and map matching enhancement to improve arrival time differences and improve positioning accuracy.
In order for the geolocation to be more accurate, at least three gateways are required to receive the packets. More gateways and a denser network will improve positioning accuracy and capacity. This is because when more gateways receive the same packet, the server algorithm gets more information, thus improving geolocation accuracy.
A new generation of hardware is needed inside the LoRa gateway to calculate some parameters used in geolocation, such as high-precision arrival time. Semtech created a reference design for the new version of the gateway in early 2016, which was successfully implemented in many gateways. The reference design includes the required high-quality timestamping capabilities and is available to authorized gateway partners. This ensures that multiple vendor deployments work consistently to provide high-quality timestamps, enabling the highest quality geolocation services.
It’s important to note that geolocation relies entirely on gateway and network technology, so once the gateway is upgraded, geolocation functionality will be available to all devices
Semtech also provides a geolocation solver program. The general solver is not a dedicated application and is independent of the end node, which provides a good start for LoRa geolocation services. Additionally, an API has been defined that allows system integrators to use third-party solving algorithms that may improve the available position accuracy. Through this open model, Semtech encourages innovation and development of solution technology to ensure continuous improvement of LoRaWAN-based geolocation.
When a packet reaches the gateway, it does not know which end device the packet came from. Therefore, the gateway timestamps each received packet and forwards it to the server. Because access to geolocation services is valuable, these timestamps are protected via encryption in the gateway. The timestamp is transmitted to the network server and Semtech authorizes the decryption function to the network service provider. The web server provider can decrypt the data depending on the service level subscribed to.
One of the biggest difficulties in providing good location is reducing multipath transmission. As shown in the figure below, some data packets go directly to the gateway, some data packets do not but have a reflected signal, and other data packets have both situations. Reducing multipath transmission by using more packet transmissions can be through more channels, more gateways, more antennas, and using machine learning or statistical techniques.
The technology based on LORA positioning includes an information transmission system, a network transmission system and an information processing system. It is characterized in that the output end of the information transmission system is connected to the input end of the network transmission system, and the output end of the network transmission system is connected to the information processing system. The input end of the processing system is connected. The information sending system includes Beacon beacon, GPS satellite, base signal tower, LORA tag and LORA area network. The input end of the Beacon beacon, GPS satellite and base signal tower is connected with LORA. The input end of the tag is connected, and the output end of the LORA tag is connected to the input end of the LORA area network;
The network transmission system includes a LORA gateway, a network connection and a wide area network. The output end of the LORA gateway is connected to the input end of the network connection. The output end of the network connection is connected to the input end of the wide area network. The information processing system includes a management system. Server, cloud network server, management client and mobile management client;
2. Controllable parameters of LoRa positioning
Frequency diversity:
By repeatedly sending a message on all available channels, geolocation results improved by 50% on average. A static end node working on an 8-channel network will improve its results by 50% by sending 8 packets on 8 different channels.
The shape of the deployment gateway mesh. The impact of gateway deployment grid is about 25%. A long fine mesh will perform 25% worse than a square mesh. Therefore, network deployment should focus as much as possible on deploying gateways in a square pattern.
Gateway Diversity:
Generally speaking, the more gateways receiving the signal, the more accurate the results. However, beyond 6 gateways, the geolocation improvements start to become less noticeable. At 3 to 4 gateways, there is about a 25% improvement, and beyond 4 gateways the geographical location improvement starts to decrease.
Antenna diversity affects the weakest signals the most. So if a device is in a position with good reception on 3 gateways, adding a weak 4th gateway, the antenna diversity will usually change the packets received on the 4th gateway from unavailable to available. In this case, it can provide a 25% location improvement.
1. The output end of the LORA area network is connected to the input end of the LORA gateway, and the output end of the wide area network is connected to the input end of the management server, cloud network server, management client and mobile management client respectively.
2. A technology based on LORA positioning according to claim 1, characterized in that the output terminals of the Beacon beacon, GPS satellite, base signal tower and the input terminal of the LORA tag are all wirelessly connected.
3. A technology based on LORA positioning according to claim 1, characterized in that the LORA tag is worn on the wrist of the human body.
4. A technology based on LORA positioning according to claim 1, characterized in that the output end of the LORA gateway and the input end of the network connection are wireless network connections.
5. A technology based on LORA positioning according to claim 1, characterized in that the output end of the management client is connected to the input end of the cloud network server.
6. A technology based on LORA positioning according to claim 1, characterized in that the mobile management client is a touch screen mobile phone.
7. A technology based on LORA positioning according to claim 1, characterized in that the information processing system is provided with a monitoring center, and the output end of the monitoring center is connected to the input end of the management server.
Keywords: lora