Full understanding of LoRa and LoRaWAN

While telecoms operators have the most prominent advantage of building and managing such a large-scale network, a long-range, high-capacity system is needed to consolidate the position in the battery-powered wireless terminal-dependent market segments – wireless sensor networks, smart cities, smart grids, smart homes, security devices and industrial controls. For the IoT (Internet of things) , only the use of a broad range of technologies will make it possible to bring the number of battery-powered wireless nodes to the projected scale.

LoRa（Long range） has received increasing attention in recent years as a long-range communication technology for Low Power Wide Area Networks (LPWAN).

LoRa Technology

LoRa is one of the LPWAN communication technologies, an ultra-long range wireless transmission solution based on spread spectrum technology adopted and promoted by Semtech company in the United States.

It is the physical layer or wireless modulation used to establish long distance communication links. Many conventional wireless systems use Frequency Shift Keying (FSK) modulation as the physical layer because it is a very effective modulation for achieving low power consumption.

LoRa is based on linear FM spread spectrum modulation, which maintains the same low power characteristics as FSK modulation but significantly increases the communication distance.

The LoRa technology itself has a very high receiver sensitivity (RSSI) and a very high signal-to-noise ratio (SNR). In addition, it uses frequency hopping technology, which is frequency-shift keyed by pseudo-random code sequences, to extend the spectrum by constantly hopping the carrier frequency and preventing fixed-frequency interference.

At present, LoRa mainly operates in global free frequency bands, including 433, 868, 915 MHz, etc..

Features of LoRa:

• Long transmission distance
• Low power consumption
• Multiple nodes in the network

LoRa Network Architecture

In a mesh network, individual end nodes forward information from other nodes to increase the communication range of the network and the size of the network area. While this increases range, it also increases complexity, reduces network capacity, and decreases battery life as nodes receive and forward information from other nodes that may not be relevant to them. The long range star architecture makes the most sense to preserve battery life when implementing long range connectivity.

If the gateway is installed in an existing mobile location with a transmit power of 20dBm, (100mW), it can cover around 2km in a highly built-up urban environment and up to 10km in a less dense suburban area. The gateway/concentrator also contains the MAC layer protocol, which is transparent to the higher layers.

The schematic diagram of the mesh topology is as follows:

 These are the four main elements of the LoRa network : End Nodes, gateways（Concentrator）,Network server, and application server. 

The LoRaWAN network architecture is a typical mesh topology in which the LoRa gateway is a transparent transmission relay that connects end devices to a back-end central server. The end devices use a single hop to communicate with one or more gateways. All nodes communicate with the gateways in both directions.

LoRa end devices

The end nodes of LoRa may be various devices such as water and gas meters, smoke alarms, pet trackers, etc. These nodes are first connected to the LoRa gateway through LoRa wireless communication, and then through 3G network or Ethernet network, they are connected to the network server. The gateway communicates with the network server through TCP/IP protocol.

LoRa Device Classes

LoRa network classifies end devices into three classes A/B/C:

Class A: Bidirectional communication end devices. This class of end devices allows bi-directional communication, and each end device uplink transmission is accompanied by two downlink receive windows. The transmission time slots of the end devices are based on their own communication requirements, which are fine-tuned based on the ALOHA protocol.

Class B: LoRa devices are battery-powered and, while similar in operation to Class A, consume more power than Class A. The LoRa gateway and the end devices intermittently open a connection window to communicate data with each other with some periodic synchronisation.

Class C: Bidirectional communication end devices with a maximum reception window. End devices in this class keep the receive window open continuously and only close it during transmission.

LoRa Alliance

The LoRa Alliance is an open, non-profit organisation founded in March 2015 under the leadership of Semtech, with Actility (France), AUGTEK (China) and KPN (Royal Dutch Telecom) as founding members. In less than a year, the alliance has developed more than 150 member companies, including IBM, Cisco, Orange and other heavyweight manufacturers.

Each link in the industrial chain (terminal hardware manufacturers, chip manufacturers, module gateway manufacturers, software vendors, system integrators, network operators) has a large number of enterprises, and the openness of this technology and the fullness of competition and co-operation have all contributed to the rapid development and ecological prosperity of LoRa.

LoRaWAN Protocol

LoRaWAN is a Low Power Wide Area Network (LPWAN) standard based on the open source MAC layer protocol introduced by the LoRa Alliance. This technology provides local, national or global networking for battery-powered wireless devices.LoRaWAN targets some of the core requirements in the Internet of Things, such as secure two-way communication, mobile communication and services such as static location identification. The technology enables seamless interoperability between smart devices without the need for complex local configurations, giving users, developers and enterprises in the IoT space free operating privileges.