Experts have suggested that Microchip's LoRa solution can easily create a stable, long-range wireless communication environment.

At the e4ds news webinar in March, Microchip's Senior Director of Wireless Communication Solutions, Ki-Beom Kim, presented on 'LoRa Solutions: Long-Range Wireless Communication Technology and Applications in Various IoT Fields.'

The lecture on that day introduced the concepts of LoRa and LoRaWAN, cases of LoRa being applied in various IoT fields, and the wireless communication performance of Microchip's LoRa solution in the field was revealed.

LoRa stands for 'Long Range' and refers to the technology itself or the LoRaWAN network protocol. It enables long-distance communication of up to 5km in urban areas and up to 15km in suburban areas.

LoRa is a wireless communication method that sacrifices data transmission rate to gain communication range. It spreads the transmitted data and despreads it at the receiving end to increase reception sensitivity and extend the communication range. Spreading data reduces the data rate.

LoRa is increasingly applicable to security, logistics, parking management, facilities, building management, environmental monitoring, leak management, and home care. For example, it is used in door locks in smart homes and is also responsible for various monitoring in smart farms. On the other hand, when LoRa is applied in areas with shadows, interference or collisions become a problem, so appropriate channel distribution and output control are required.

There are three factors that determine the distance and data transmission speed in LoRa settings: △Spreading Factor (SF), △Bandwidth (BW), and △Forward Error Correction (FEC) Code Rate (CR).

SF (Spreading Factor) adjusts data spread information. The more data is spread, the greater the spreading gain, which increases the reception sensitivity and communication distance.

Bandwidth (BW) controls the width of the communication channel. As the channel width becomes narrower, the reception sensitivity increases, but the transmission time increases. It can be set to 125 kHz, 250 kHz, and 500 kHz, and 125 kHz bandwidth is used domestically.

Lastly, Forward Error Correction (FEC) Code Rate (CR) increases the communication distance by enabling error detection and seeding when overlapping data transmission. Code Rate sets the degree of overlap, usually 4/5 is used. IEEE 802.15.4 is a low-power wireless communication technology characterized by low data transmission rates. It is widely used as a lower layer of communication protocols such as Zigbee, Wi-Thon, and MyWi. It is a message encryption function for security, and protects messages by encrypting and decrypting transmitted messages with an encryption key distributed to each node.

'LoRaWAN' is a network protocol defined by the LoRa Alliance. There are four layers: end devices, network servers, and application servers.

LoRa messages sent to the end device are received by the gateway and transmitted to the network server. LoRa wireless communication occurs between the end device and the network, and the gateway network server and application server sections are standard IP communication sections.

The message transmitted from the end device to the server is called an uplink message, and the opposite is called a downlink. The transmission method varies depending on class A, B, and C. A has a large delay, but is the most advantageous in terms of power consumption. B is possible for a certain period of time, and C is possible continuously. Since LoRa has a long communication distance, multiple gateways can simultaneously receive data transmitted by end devices.

■ Microchip provides full stack LoRa solution

MiWi (Microchip wireless) is Microchip's wireless network protocol stack. It supports both 2.4Ghz and 6 sub bands. It features low power consumption and light weight, and has the advantage of being freely usable without a separate license.

Among the main functions of MiWi, △'Active Scan' is a function that collects information on other MiWi networks existing in each channel. It helps select a channel with smooth communication by screening by PAN, signal strength, etc. △'Energy Scan' is used when measuring the channel status before data transmission or when creating a network by measuring the noise level of the channel. △'Frequency Agility' is a function that moves the entire network to another channel if the currently used channel is congested. △'Network Freezer' is a function that quickly recovers the network by saving the existing network information and immediately restoring the communication status when the power is cut off, etc.

Senior Kim introduced ICs and modules as Microchip's LoRa solutions. "Microchip's LoRa ICs enable flexible design and are low-priced, and the modules have obtained major national wireless certifications such as the FCC and are effective in shortening the period," he claimed.

The dual SAM R34 is a SiP solution with an integrated 48MHz Cortex M0+ MCU and transceiver. It comes with a certified design package and LoRaWAN stack, and also provides Microchip’s Studio capabilities. It also includes various peripherals such as ADC.

The LoRa transceiver supports from 137MHz to 1020MHz, with a maximum radio output of 20dBm and a receiver sensitivity of -148dBm. The current consumption in ultra-low backup mode is 790nA, which is the lowest in the industry. The WLR089 is an already certified module, which reduces verification time. Precisely matched antennas ensure safe wireless performance.

The LoRa evaluation board can be used for performance testing as well as for product design with the accompanying circuit diagram, and an onboard debugger is included, eliminating the need for a separate debug tool.

LoRa software provided by Microchip was also introduced. LoRa P2P & MiWi and LoRaWAN implement apps with APIs. With the LoRaWAN stack, protocols such as MiWi can be built more flexibly and applied to various applications.

Microchip presented field test cases of LoRa solutions in urban and suburban areas. In the suburban area of Bibongsan, 15km communication was possible without any problems, and in the urban area of Gasan-dong, Seoul, due to various obstacles, the measurement range was about 6km. The LoRa IoT system demo consists of a LoRa network, gateway, cloud service, and visualization.