Radio waves in the 400- to 900-MHz range may pass through some obstructions, depending on their composition, but will be absorbed or reflected otherwise. This means that the signal can potentially reach as far as the horizon, as long as there are no physical barriers to block it. Elevating LoRa devices—placing them on rooftops or mountaintops, for example—will maximize their range. Other factors, such as antenna gain, will also have a large impact on range.
Range depends on numerous factors—indoor/outdoor gateways, payload of the message, antenna used, etc. On average, in an urban environment with an outdoor gateway, you can expect up to 2- to 3-km-wide coverage, while in the rural areas it can reach beyond 5 to 7 km.
LPAWAN is the communication protocol and system architecture for the network over physical radio layer enabling the long-range communication link. The LPAWAN protocol and network architecture directly influence the power independant lifetime of a node, network capacity, quality of service, security, and the variety of applications served by the network.
Another key feature of LPAWAN is its ability to support bidirectional communication. This means that an end device (sensor) can send a message to the network (i.e., sensor data, occupancy, location) as well as receive messages from the network back to the device. Thanks to this, LoRa devices can be programmed or designed to deliver status indicators to remote locations.
Security has always been an important aspect for any wireless technology. LPAWAN utilizes one layer of security over the data delivery channel and two layers of security over the back notification channel: the first layer of security ensures the network operator doesn’t have access to the end user’s application data and the second layer ensures authenticity of the node in the network. Block cypher encryption is used in both layers.
A very interesting feature of LPAWAN is localization without the need of GPS. This is especially useful for tracking assets and sensors, since it’s very battery-efficient. LPAWAN sensors can support tracking applications by using Differential Time of Arrival techniques to determine approximate location to the nearest city block.
This coarse-grained triangulation can be achieved when a device is transmitting to at least three gateways in a similar manner as GPS receivers. With foreknowledge of each gateway’s physical location and by detecting the difference in time between all of them as the signal arrives, an application can compute the approximate position of the signal’s origin.