LoRa is technology of wireless communication for IoT

According to IoT Analytics on the second half of 2020 is the most widespread technology of low-power global networks (LPWAN). The LoRa technology is created for the intercomputer (M2M) interaction and represents a combination of a special method of modulation of LoRa and the open protocol of interaction LoRaWAN. This technology of communication is developed for IoT in such a way that can service up to 1 million devices in one network, giving them autonomy up to 10 years from one battery of the AA format.

Specifications

Technical characteristics of LoRa slightly differ depending on the region of application. Also are focused on reliable service of signals and low power consumption

Europe and Russia

LoRaWAN defines ten channels, eight of which have different data transfer rate from 250 bps to 5.5 kbps, one channel LoRa at high data transfer rate of 11 kbps and one channel FSK with a speed of 50 kbps. The maximum power output resolved ETSI (The European institute of telecommunication standards) in Europe is +14 dBm, except for the range of G3 for which the value in +27 dBm is allowed.

Technology

Physical layer

The method of modulation of the same name which was patented by Semtech company is the cornerstone of LoRa technology. This method is based on the principle of expansion of a range and sweep frequency modulation. In the course of transfer data are coded by broadband impulses from decreasing or increasing, in a certain time span, frequency. This solution allows to make the receiver steady against frequency deviations from rated value that reduces quality requirements of the generator and allows to use simple quartz resonators. Due to use of technology of expansion of a range, the LoRa receiver can demodulate a signal which has level on 20 dB of a noise level. The high sensitivity of receivers (-148 dBm) allows to use to apply this technology at long distances, providing small energy consumption and high stability of communication.

LoRaWAN

Main article: LoRaWAN

LoRaWAN is the open protocol of communication which defines system architecture. This protocol provides topology like "star". LoRaWAN was developed for the purpose of the organization of communication between inexpensive devices which can work from batteries (accumulators). For providing the acceptable relation of transmission rate to energy consumption, the protocol provides different classes of nodes. The LoRaWAN protocol defines a specific set of data transfer rates, but implementation of the physical layer of the OSI model will depend on the selected chip.

Network architecture

Unlike a large number of the existing networks using mesh-architecture where nodes of network, for expansion of a covering transfer information from one to another, LoRa – network "star" uses topology. It allows to reduce power consumption of devices (due to lack of need of transfer of packets from other devices) and to simplify architecture of network.

In LoRaWAN network the node contacts not the specific gateway, and transfers data to several gateways. Each gateway sends the received packet from a final node through transport (a cellular network, Wi-Fi, Ethernet or another) on a cloud server. The server manages network, discards excess packets, executes security checks, plans an optimal route of transfer of the confirmatory message and manages data transfer rate. Use of such architecture allows to get rid of the procedure of a handoff when moving mobile sensors within action of network. Nodes in network work in an asynchronous mode and transfer data on a measure of accumulation or on interruption. For access to resources of network the Aloha method is used. Failure from permanent synchronization of devices (as in mesh-or cellular networks) also allows to save battery power. In network with "star" topology it is difficult to organize high capacity of network along with the big area of a covering. In LoRaWAN apply adaptive data transfer rate to implementation of such opportunity and use multichannel multi modem transceivers in gateways that messages could be transferred at the same time on several channels. Critical factors for capacity - the number of simultaneous channels, data transfer rate (time on air), length of payload and how often nodes conduct transfer. As LoRa represents modulation on the basis of expansion of a range, signals practically of an ortogonalna each other when different expansion ratios are used. At change of expansion ratio effective data transfer rate changes too. The gateway uses this property, having an opportunity to receive several different data transfer rates on one channel at the same time. If the node has good connection and is close to the gateway – he can use higher data transfer rate, at the same time time of its stay on air becomes less that opens "window" for transfer from other nodes. The network can be under construction proceeding from necessary capacity, for example it is possible to increase power in network, to determine bigger number of gateways, but to reduce the number of gateways which will be wiretapped by clients and to increase capacity of the channel by 6-8 times.

Central server

The problem of possible collisions at simultaneous data transmission by several points is solved by the central LoRaWAN server of network which selectively sends to nodes (end-node) of network managing commands via gateways, selecting timeslots for transfer and acceptance is individual for each endpoint (end-node). Addressing happens on 32-bit DevAddr unique for each node (end-node).

The central LoRaWAN server of network makes decisions on need of change of data transfer rate points (end-node), the transmitter power, the choice of transmission channel, its beginning and duration, controls a charge of batteries of final nodes (end-node), i.e. completely controls all network and manages each subscriber device separately.

Each LoRaWAN a data packet, sent by a final node, (end-node) incorporates the unique identifier of the AppEUI application belonging to the application on the server of service provider for which it is intended and this identifier is used by the central LoRaWAN server of network for further routing of a packet and its processing by the application on the server (App Server) of service provider.

In practice, as a rule, services of service provider are provided by producer of terminal units (end-node) which supports service for data processing where packets from the LoRaWAN server of network for work with these data to end users are routed. ^[1]

Classes of devices

The end devices servicing different applications can impose different requirements. For optimization of profiles of applications classes of devices are used.

Classes set a necessary ratio between delays on the descending line and battery life.

• Bidirectional terminal units (class A): terminal units of a class A allow bidirectional communication at which transfer of the uplink channel of each end device alternates two short receive windows on the descending line. The slot for transfer is planned by the end device proceeding from own communication requirements, but can slightly move on time proceeding from access as ALOHA. Transactions of class A have the lowest power. Transfer on a downside channel from the server is possible only after the following planned air "up".

• Bidirectional terminal units (class B): in addition to accidental windows there are additional, planned in certain time, receive windows "down". The device for an exit to communication in due time receives special, synchronized on time, the beacon of the gateway also listens to air in the planned time.

• Bidirectional terminal units (class C): End devices listen to air all the time, receive windows are closed only on transmission time.

Security in network

In IoT tough security is necessary. For accomplishment of these requirements two security levels are used: level of network and level of the application. Network security guarantees authenticity of a node in network while the security level of applications guarantees that the operator of network has data access no appendix of the end user.

LoRa application

Smart city

Main article: Smart cities (Smart cities)

The LoRa system can well be suitable for an ecosystem of the smart cities, so the city is an accurate geographical zone. Though the choice of specific implementation often depends on topology, density of building and solvency of the population. LoRa networks due to work in not licensed range can offer big flexibility and smaller cost of deployment and ownership in comparison with cellular networks. Distinguishers of solutions for the smart city is that final application are not demanded permanent broadband connection and big time on air. Such level of requirements will well be approved with LoRa opportunities. Within the smart city of the solution LoRa can collect data on climate and air quality, for example, for making decision on need of processing of roads with reagents. Monitoring of fullness of trash cans can serve as other scenario. Sensors of humidity of the soil can be used for timely inclusion of watering of plants in parks. Except LoRa sensors it is possible to use for activation of street lighting, in the system of information messages about arrival time of transport. LoRa allows to deploy those solutions which local authorities consider necessary, and due to technology flexibility of LoRaWAN, connection it is possible to implement in any place where there is an access to a data network.

Tracking of assets

Market development of IoT of devices led to the fact that except direct tracking of the position information of an object that was implemented on means of cellular and satellite networks, became possible to collect object state-of-health data (temperature, speed, data on specific objects in a load). Wide circulation of LPWAN of networks becomes serious break as such monitoring. In the course of tracking of assets the continuity of tracking, even is important at cross-border movement with respect thereto technology should be global and easily developed in different areas and the states. At the same time the industry of logistics does not require the large volume of transmitted data with respect thereto application of LoRa is the suitable solution as allows to deploy the energy efficient solution. Besides, at the expense of high capacity LoRa can effectively be used in big warehouse complexes which process tens of thousands of departures a day.

Smart buildings

Main article: Smart house (Smart home)

At an initial stage smart buildings included separate solutions of Internet of Things and implemented generally solutions for energy saving. With development of IoT technologies serious asset management, including monitoring of all life support systems, predictive technical equipment maintenance, control of state of environment in workplaces became possible. By 2020 many organizations begin to understand that the smart building is advantage not only in economy of funds for operation, but even means for attraction and deduction of personnel. For the millenials who got used automation everywhere give preference in the work choice to those organizations which will organize a convenient and attractive working environment, and with respect thereto smart buildings become a part of our life. The applications providing free sharing of jobs the individual microclimate and ecology, maintenance of purity require more active implementation of Internet of Things. The research of IoT Berg Insight analytical company announces that for the end of 2018 the size of the market of solutions for smart buildings was 151 million items of equipment. It is expected that the annual average gain (CAGR) till 2022 will make 33%. And the number of the installed devices will reach 483 million. In 2018 the number of the devices connected through cellular networks did not exceed 4.5 million and according to forecasts will not exceed 19.4 million in 2022. The IoT Analytics company says that smart buildings take the 3rd place (12%) after the smart cities (23%) and industrial solutions (17%) on number among implementable IoT of solutions in the world.

New projects of Internet of Things appear everywhere, however we noted that projects on subjects of the smart city and smart buildings grew more, than others

As of the middle of 2020 of LoRa from 105 million devices the most widespread LPWAN technology. The solutions Lora are applied in service of the HVAC systems and electronics, in electricity metering and water supply, control of the environment, management of supply of electricity, forecast cleaning of premises.

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