Lora and LoRaWAN Technology Overview

1. Introduction

The purpose of this article is to provide a guided technical overview of Lora and LoRaWAN technologies. Low-Power wide area network (Lpwan) supports the vast majority of IoT devices that are expected to be hundreds of millions of orders of magnitude. LoRaWAN optimizes the battery life, capacity, range, and overhead of Lpwan in a bottom-up manner at design time. This paper gives an overview of the LoRaWAN norms in different regions, and compares several competing technologies in the Lpwan field at a relatively high level. 2. What is Lora

Lora is a physical layer or wireless modulation that is used to create long-distance communication connections. Many traditional wireless systems use frequency shift keying (FSK) modulation as a physical layer because it is a very efficient way to gain low power consumption. Lora based on chirp FM spread Spectrum modulation, it maintains the same low-power characteristics as FSK modulation, it is important to increase the communication distance. Linear FM spread spectrum is used in military and aeronautical communications in dozens of years, thanks to its long-distance communication capability and anti-jamming robustness, Lora is the first commercial area of this technology for low-power applications.

Long Distance (LoRa)
The strength of Lora technology is remote technology. A single base station or gateway can cover the entire city or hundreds of square kilometres. The farthest distance depends on the environment or the obstacles within a given distance, but the Lora and LoRaWAN link budgets are superior to any other standard communication technology. The link budget, usually given by DB, is the primary factor in determining the range of communications in a particular environment. The following figure is an overlay of the application of Lora technology. The entire city is easily covered under the premise of a minimum number of base stations.
3. Where Lpwan fit

A technology that does not serve all IoT scenarios. WiFi and Btle are widely adopted standards, which mainly serve the connection between personal devices and other related applications. Cellular technology is better suited for devices that require high data-bandwidth power supplies. Lpwan provides years of battery life and is designed to serve sensors in different environments that require a small amount of data to be sent dozens of times per hour over a long distance.

key factors of Lpwan Network architecture communication distance low power consumption or battery life disturbance Robust network capacity (maximum number of nodes allowed in network) network encryption single or dual communication application services Diversity 4. What is LoRaWAN?

LoRaWAN defines the communication protocol and system architecture of a network when a long-distance communication link is enabled to Lora the physical layer. Protocol and network architecture have a decisive impact on the diversity of battery life, network capacity, service quality, encryption and application services of the nodes.

Network Architecture
Many of the networks that have been deployed use the mesh network architecture. In a mesh network, the independent terminal node can relay the information of other nodes to enlarge the range of communication and network coverage. Increasing the range also increases complexity, reduces network capacity and battery life, because nodes need to receive and relay information about other nodes, but that information has nothing to do with itself. Long-distance star architectures are most beneficial for extending battery life when using long-distance connections.

In a LoRaWAN network, nodes do not associate specific gateways. Instead, the data transfer of a node is usually received by multiple gateways. Each gateway will transfer packets received from the terminal node to the cloud network server via many backhaul (cellular, Ethernet, satellite, or WiFi). The large computation and the high complexity operation are pushed to the network server, which manages the whole network and filters the mass of receiving packets, completes the encryption check, dispatches the best gateway to complete the response, adjusts the data rate and so on. If a node is hand-held or mobile and does not need to be handed over from one gateway to another, this is a vital feature that allows asset tracking to apply--iot to a major application.

Battery Life
When the nodes in the LoRaWAN network are ready to send the data, the communication between them is asynchronous, whether it is an event-driven or a scheduler. This type of protocol can refer to the Aloha approach. In a mesh network or a synchronous network, such as a cellular network, nodes need to wake themselves up frequently to maintain synchronization with the network and to check messages. This synchronization consumes a lot of energy and is the first driver of a lower battery life. In recent studies and comparisons completed by GSMA, LoRaWAN is 3 to 5 times times the battery life of all other technologies.

Network Capacity
In order for the star network to be available at a distance, the gateway must have a very high capacity or be able to receive data from a very large number of nodes. The high network capacity of the LoRaWAN network relies on the use of adaptive data rates and the use of a multi-channel Multimode transceiver at the gateway, so that synchronization messages on multiple channels can be received. The most important factor influencing the effective capacity is the number of channels, data rate, net load length and node transmission frequency. Because Lora is based on spread spectrum modulation, when different extension factors are used, the signals are orthogonal to each other. When the extension factor changes, the effective data rate also changes. Gateways take advantage of this property to receive multiple different data rates simultaneously in the same channel. If a node has a good connection and is close to the gateway, it is not necessary to always use the lowest data rate and occupy a higher spectrum than the spectrum it needs. By increasing the data rate, data is shortened in the air, potentially raising the space for other nodes to transmit data. The adaptive data rate also optimizes the battery life of the node. For the adaptive rate to take effect, you need to peer up and down links. These features allow the LoRaWAN network to have a very high capacity and make the network more reliable. A network can deploy the least needed infrastructure, and if more capacity is needed, the gateway can be increased to 6 to 8 times times larger capacity. Other Lpwan do not have lorawan reliability, because the technical tradeoffs limit the downward link capacity or the downward link distance from the up link to the wrong distance.

Device Type-not all nodes are born equal
Terminal equipment services have different applications and have different requirements. In order to optimize the terminal application scenario, LoRaWAN utilizes different types of equipment. Device types weigh Network down-link communication latency and battery life. Downlink latency is an important factor in the application of a control or execution type.

Two-way terminal equipment (Class A): A class of terminal equipment allows two-way communication, each terminal uplink transmission followed by two short downlink receiving window. The transmission time slot scheduling of terminal equipment is based on its own communication demand and a small variable (Aloha type protocol) based on stochastic time basis. The Class A equipment runs in the lowest power consumption terminal system, the application only needs downlink communication from the server, which is located after an uplink transmission which has been sent by the terminal device. Downlink traffic from the server at any other time has to wait until the next scheduled uplink transmission.

Two-way terminal equipment (class B) with scheduling receive slots: In addition to the random receive window of Class A devices, Class B devices open additional receive Windows during the scheduled time. It receives a time synchronous broadcast from the gateway for the terminal device to open its receiving window at the scheduled time. It allows the server to wait until the terminal device is listening.

Two-way terminal (Class C) with a maximum receiving time slot: The Class C device has an almost continuously open receive window, which closes the window only when it is transferred.

Encrypt
For any Lpwan, the combination of encryption is extremely important. LoRaWAN uses two layers of encryption: The network layer and the application layer. The network layer encryption ensures that the nodes are authenticated in the network, and the application layer encryption ensures that the node network operation does not access the end user's application data. Use an IEEE EU164 discriminator for AES encryption when key exchange is used.

Each technology option has a trade-off, but LoRaWAN can be widely applied to many IoT applications in the network architecture, device type, encryption, capacity and optimization for mobile addressing.

The LoRaWAN specification is slightly different in different regions, based on the frequency bands and regulatory requirements that are allowed in different regions. European and North American LoRaWAN norms have been developed, but other regions are still developed by the Technical Committee. Join the Lora Alliance as a contributor and participate in the technical Committee's access to Asia's key corporate solutions. 5. Lpwan Technology Option Comparison

There are many activities in the IoT field that compare Lpwan options, not just technical comparisons but also business model observations. The Lpwan network is being deployed because of strong business reasons to support immediate deployment, and the cost of deploying on an unauthorized channel is far less than the 3G software update. The questions to be answered before comparing the different Lpwan technologies are: to build a large and diverse application of flexible communication protocols whether encryption technology, scope, capacity, dual-channel communication, anti-jamming robust network deployment overhead, terminal node BOM cost, Battery cost flexible business model required for ecosystem solutions Availability of terminal products to ensure the strength of the ROI ecosystem deployed by the network to ensure the long-term and quality of the solution-