What is LoRa ?
“LoRa stands for Long Range Radio. It is the wireless technology mainly targetted for M2M and IoT networks “
History of LoRa The technology behind LoRa™ was developed by Cycleo, a French company acquired by Semtech in 2012. LoRa™ is proprietary, but it appears to use some sort of "simpler" CSS (Chirp Spread Spectrum) pulsed FM "sweeping frequency" modulation rather than DSSS (Direct Sequence SS) or FHSS (Frequency Hopping SS)
There are several key elements of the LoRa wireless system. Some of its key features include the following:
Long range: 15 - 20 km.
Millions of nodes
Long battery life: in excess of ten years
LoRa technology consists of several elements:
RF interface / physical layer : The LoRa physical layer governs the aspects of the RF signal that is transmitted between the nodes or endpoints, i.e. the sensors and the LoRa gateway where signals are received. It governs aspects of the signal including the frequencies, modulation format, power levels, signaling between the transmitting and receiving elements, and other related topics. Read more about the LoRa physical layer.
LoRa network architecture: Apart from the RF elements of the LoRa wireless system, there are other elements of the network architecture, including the overall system architecture, backhaul, server and the application computers. Read more about the LoRa network architecture.
LoRa frequency bands :
The LoRa wireless system makes use of the unlicensed frequencies that are available worldwide. The most widely used frequencies / bands are:
• 868 MHz for Europe
• 915 MHz for North America
• 433 MHz band for Asia
Using lower frequencies than those of the 2.4 or 5.8 GHz ISM bands enables much better coverage to be achieved especially when the nodes are within buildings.
Although the sub-1GHz ISM bands are normally used, the technology is essentially frequency agnostic and can be used on most frequencies without fundamental adjustment.
LoRaWAN™ defines the communication protocol and system architecture for the network while the LoRa® physical layer enables the long-range communication link. The protocol and network architecture have the most influence in determining the battery lifetime of a node, the network capacity, the quality of service, the security, and the variety of applications served by the network.
Network Architecture Many existing deployed networks utilize a mesh network architecture. In a mesh network, the individual end-nodes forward the information of other nodes to increase the communication range and cell size of the network. While this increases the range, it also adds complexity, reduces network capacity, and reduces battery lifetime as nodes receive and forward information from other nodes that is likely irrelevant for them. Long range star architecture makes the most sense for preserving battery lifetime when long-range connectivity can be achieved.
In a LoRaWAN™ network nodes are not associated with a specific gateway. Instead, data transmitted by a node is typically received by multiple gateways. Each gateway will forward the received packet from the end-node to the cloud-based network server via some backhaul (either cellular, Ethernet, satellite, or Wi-Fi). The intelligence and complexity is pushed to the network server, which manages the network and will filter redundant received packets, perform security checks, schedule acknowledgments through the optimal gateway, and perform adaptive data rate, etc. If a node is mobile or moving there is no handover needed from gateway to gateway, which is a critical feature to enable asset tracking applications–a major target application vertical for IoT.
The LoRaWAN™ specification varies slightly from region to region based on the different regional spectrum allocations and regulatory requirements. The LoRaWAN™ specification for Europe and North America are defined, but other regions are still being defined by the technical committee. Joining the LoRa® Alliance as a contributor member and participating in the technical committee can have significant advantages to companies targeting solutions for the Asia market.