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LoRa does not meet the technical requirements of the Ministry of Industry and Information Technology in Shenzhen?

  • Categories:News Center
  • Time of issue:2021-01-14 09:51
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(Summary description)LoRa is a long-distance, low-power wireless radio frequency communication technology. It is a secure and controllable private Internet of Things (IoT) that users can use unlicensed frequency bands to set up. At the end of last year, following the publication of the "Announcement No. 52 of the Ministry of Industry and Information Technology of the People's Republic of China, 2019" to further regulate the management of micro-power short-range radio transmission equipment, many media speculated that this specification was formulated for LoRa. I am afraid that LoRa will be cool (Editor's note: the meaning is finished, miserable, and dead). But to this day, LoRa is still in rapid development in China.

LoRa does not meet the technical requirements of the Ministry of Industry and Information Technology in Shenzhen?

(Summary description)LoRa is a long-distance, low-power wireless radio frequency communication technology. It is a secure and controllable private Internet of Things (IoT) that users can use unlicensed frequency bands to set up. At the end of last year, following the publication of the "Announcement No. 52 of the Ministry of Industry and Information Technology of the People's Republic of China, 2019" to further regulate the management of micro-power short-range radio transmission equipment, many media speculated that this specification was formulated for LoRa. I am afraid that LoRa will be cool (Editor's note: the meaning is finished, miserable, and dead). But to this day, LoRa is still in rapid development in China.

  • Categories:News Center
  • Author:Zhao Mingcan
  • Origin:
  • Time of issue:2021-01-14 09:51
  • Views:
Information

LoRa is a long-distance, low-power wireless radio frequency communication technology. It is a secure and controllable private Internet of Things (IoT) that users can use unlicensed frequency bands to set up. At the end of last year, following the publication of the "Announcement No. 52 of the Ministry of Industry and Information Technology of the People's Republic of China, 2019" to further regulate the management of micro-power short-range radio transmission equipment, many media speculated that this specification was formulated for LoRa. I am afraid that LoRa will be cool (Editor's note: the meaning is finished, miserable, and dead). But to this day, LoRa is still in rapid development in China.

A few days ago, at the "2020 LoRa Innovation Application Forum", a number of Semtech executives put forward answers to a series of technical questions about LoRa, including the key question of whether LoRa meets the 52nd file of the Ministry of Industry and Information Technology of China.

What is LoRa?

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According to reports, LoRa is a physical layer wireless digital communication modulation technology, called spread spectrum continuous frequency modulation modulation technology (Chirp Modulation). Common wireless digital communication modulation technologies are FSK, ASK, and PSK. Operators' NB-IoT, 4G, 5G, Wi-Fi, Bluetooth, etc., almost all common digital wireless communication technologies use FSK, ASK and PSK are three modulation technologies for communication.

LoRa is just a physical layer modulation technology, and all LoRa chips on the market now only complete simple physical layer work. Other chips on the market such as Wi-Fi, 2G, 3G, NB-IoT, etc., all have their own protocol stack. Figure 1 shows the network layer + data link layer + physical layer in the OSI model.


Figure 1 Schematic diagram of OSI network layering.

What is the networking method of LoRa?

LoRa is only a modulation technology of the physical layer, and its networking mode can be selected according to different applications and requirements. Commonly used in practical applications: point-to-point, star-shaped, tree-shaped, mesh (Mesh) and other networking forms.

As shown in Figure 2, the LoRa ecosystem in foreign countries is mainly LoRaWAN, which is the LPWAN technology used by operators, while the main applications of LoRa in China are private networks and private networks, which are called "Long Wi-Fi". Wi-Fi is exactly the same. Compared with Wi-Fi, LoRa has the characteristics of long working distance, low power consumption, and low transmission rate.


Figure 2 Schematic diagram of LoRa network.

LoRa's network is flexible and convenient: deploy according to demand, plan and deploy the network according to application needs; according to the on-site environment, according to the terminal location, reasonable deployment of gateways and terminal equipment. The expansion of the network is very simple, and the coverage can be enhanced or expanded at any time according to the changes of the node scale.

At the same time, LoRa can be independently networked: individuals, enterprises, or institutions can deploy private/proprietary networks, enterprise networks or industrial networks (unlicensed frequency bands). Most Internet of Things applications are regional. Small-scale networks can solve the problem. Regional LANs are an effective and necessary supplement to the public network.

LoRa radio specification requirements

On November 28, 2019, the Ministry of Industry and Information Technology issued the "Announcement No. 52 of the Ministry of Industry and Information Technology of the People’s Republic of China in 2019" (hereinafter referred to as Announcement No. 52, Reference 1), which further regulates micro-power short-range radio transmission equipment ( Hereinafter referred to as micro-power equipment) management.

Understanding of Announcement 52:

1. Limited to small-scale networking applications such as buildings, residential communities and villages

LoRa is classified as a transmission method of LPWAN, which can achieve a transmission distance of 1~10KM on open ground. According to Announcement No. 52, in the frequency range of 470~510MHz, the long-distance characteristics of LoRa will be limited to a certain range, which means that LoRa will not be covered by the operator's network in China during this frequency. But if necessary, LoRa can still connect to the Internet with other communication methods (such as 4G, etc.), connecting multiple LoRa small networks into interconnected IoT applications (Figure 3).


Figure 3 Schematic diagram of the network structure of LoRa combined with the public network in a small area.

The technical indicators of this announcement clearly require the range of areas that can be used (such as smart manufacturing management system solutions applied to construction buildings, smart construction site management systems applied to residential communities, smart homes applied to construction buildings, and smart agriculture applied to villages. Article provisions).

2. Single channel transmission at any time

All the chips released by Semtech, which is currently leading the LoRa technology, support a single channel to send data. Therefore, the chip functions meet the requirement of single channel transmission at any time.

3. Civilian metering equipment should have interference avoidance functions such as "search before launch" and cannot be adjusted or closed by the user

Semtech’s LoRa chip itself already provides the channel activity detection (CAD) function, which has provided a good technical basis for interference avoidance functions such as "search before launch". At the same time, the LoRa chip has a frequency hopping function, and interference can also be avoided through frequency hopping. In addition, the LoRa gateway chip also enables channels and data rates that are orthogonal to each other, providing additional robustness in avoiding interference.

In addition, interference avoidance functions such as "search before launch" can reduce the probability of data collision and improve the reliability of the communication system. On the other hand, the reduction of collision probability can reduce the probability of retransmission, thereby reducing power consumption. Starting from the application requirements, most applications hope to improve the performance of the system through interference avoidance functions such as "search before launch", so this rule should not be regarded as a restriction.

4. If the frequency used is the same as the frequency of local sound and TV broadcasting stations, it cannot be used locally; if it interferes with the reception of local sound and TV broadcasting, it should be stopped immediately, and the interference can be eliminated or adjusted to a non-interference frequency before restarting. use

This requirement applies to all micro-power devices. The third point of Announcement No. 52 clearly defines the regulations for the reasonable use of frequency band resources by devices in the ISM frequency band (Figure 4). Since the frequencies of TV and broadcasting stations in various places are basically fixed, as long as they avoid such frequencies when they are deployed and used, the announcement requirements can be met.

Semtech's LoRa chip has the functions of "search before launch" and frequency hopping. It can detect whether there is a local broadcast signal on the current frequency before transmitting the signal, and perform frequency hopping processing if a local broadcast signal is found.

In view of China's specific national conditions, the LoRa Alliance proposes standards for multiple sets of communication channels, which can be selected according to the fixed frequency of the local radio station.

5. Transmission power limit: 50mW (erp). Transmitting power spectral density limit: 50mW/200kHz(erp) for occupied bandwidth less than or equal to 200kHz; 10mW/100kHz(erp) for occupied bandwidth 200~500kHz

For networking in buildings, residential communities, etc., due to the short distance, even if the transmission power is low, it can still meet the communication needs. If it is a smart agriculture application within a village, the signal attenuation is relatively insignificant because the village is relatively empty, and even a lower transmission power can still cover a larger area.

erp 50mW is already a large output power, which is equivalent to 50mW output power connected to a 2dBi antenna. Since the node size in indoor applications is relatively small now, and many small-size antenna gains are around -3dBi, the output power of the LoRa node can reach 22dBm, which still meets the above specifications.

6. Duration of single launch: no more than 1 second

The spreading factor parameter of LoRa has the characteristics that a small spreading factor has a faster data rate, and a larger spreading factor has a stronger anti-interference ability. The spreading factors of LoRa and the corresponding data loads are shown in Table 1.


Table 1 LoRa spreading factor and load specification table (B refers to byte group).

Table 2 is based on LoRa commonly used parameters (Bandwidth=125kHz, Preamble=8, Coding rate=4/5) and a set of theoretical transmission time and data length relationship (unit: ms) in the recessive header mode.


Table 2 Transmission time (ms)-data payload (B is byte).

It can be seen from Table 2 that under the settings of Bandwidth=125kHz, Preamble=8, and Coding rate=4/5, 169.22ms, 297.47ms, 533.5ms, and 985.09ms are used to transmit 100Bytes data, which are all less than the 1s limit. Although the transmission time is longer for SF11 and SF12, shorter data packets can still be transmitted within the limit of <1s, and if the bandwidth and other parameters are changed, SF12 can be used to transmit longer data packets. LoRa is a narrowband technology. For example, applications such as smart homes and smart communities require the transmission of as little data as possible regardless of application requirements or power consumption requirements, so the duration of a single transmission will not exceed 1s.

Generally, in smart buildings and smart home applications, the SF7 125kHz setting is used. At this time, the flight time of a communication packet is generally less than 100mS.

7. Occupied bandwidth: not more than 500kHz

The LoRa chip supports a variety of bandwidth settings up to the 500kHz limit.

Announcement No. 52 helps the development of LoRa ecology in China:

The announcement regulates the technical parameters of LoRa and provides a good environment for the long-term development of LoRa technology;
There are laws to follow, announcements provide a basis for standardizing industry market behavior, determining legal boundaries, and reducing the risk of corporate violations;
This announcement is a comprehensive specification of the production, import, sales and use of micro-power equipment. Therefore, the official announcement of the announcement is a reassurance for the industry from the policy level. No matter how much the impact on itself is, all companies at least Obtain the definite definition of legality and illegality, then you can conduct business in the legal category.
LoRa communication security

To analyze whether a piece of data is safe from a technical perspective, it can be analyzed through four aspects: the radio frequency physical layer, the data transmission process, the security encryption algorithm, and the application layer.

From the analysis of the entity layer, the security of the data is mainly reflected in the strong concealment of the signal. Strong concealment is also called Low Probability of Intercept (LPI), that is, it is not easy to be detected and has little interference to various narrowband communication systems. As shown in Figure 5, the data before spreading is higher than the noise base, and the signal is very easy to detect. When the signal is spread spectrum, the signal is completely under the noise floor and cannot be detected by energy intensity. This is also the reason why the military, communications and other industries have been using spread spectrum technology as a means of communication.


Figure 5 Concealment analysis of spread spectrum technology.

Compared with the communication rate, the spread spectrum signal is expanded in a relatively wide frequency band, and the power in the unit frequency band is very small, and the signal is submerged in noise, which is generally not easy to be found and has better concealment. Furthermore, since the spread spectrum signal has a very low power spectral density, it has little interference with various narrowband communication systems used. In terms of security, LoRa technology also inherits the advantages of spread spectrum technology, and it is difficult for general equipment to detect and interfere with LoRa signals.

Among all the Internet of Things communication technologies, LoRa technology can demodulate 20dB under noise (Figure 6), while other Internet of Things communication technologies must have a certain intensity higher than the noise to achieve demodulation.


Figure 6 LoRa modulation anti-noise characteristic diagram.

Waveforms of other IoT communication technologies can be captured by devices such as spectrum analyzers. Similarly, these communications materials may also be disturbed or forged. The LoRa technology has better concealment and anti-interference characteristics, and has strong physical layer security characteristics.

From the analysis of the data transmission process, the data of the terminal equipment using public network technology first arrives at the base station, then reaches the mobile switching center, and finally reaches the operator’s cloud, and then the final data is forwarded to the client application or the customer’s cloud. The data needs to be sent to the operator’s cloud first and then sent directly to the client. The LoRa data of the private network is collected and calculated directly locally, and the data will not even leave the scope of the park. The farther the data is transmitted, the more the number of transfers, the higher the security risk, and the use of private network technology data can be completely stored locally, and the data is always in your own hands. Many government and enterprise networks realize network security through the isolation of internal and external networks. If a private network is used, it can directly connect to the internal network of the original government and enterprise, and the security level is very high. From the analysis of the data transmission process (network layer analysis), the LoRa private network/private network has high security characteristics.

From the analysis of data encryption methods, the public network represented by mobile cellular network technology uses the same encryption method for convenience and efficiency, so it is easy to break. Because of the universality of the public network, it is impossible to do too many customized services for security, and it must balance security and performance. Private networks are completely different. They can be armed into "armored vehicles" according to the needs of customers. Data security encryption algorithms can do their best. For security, data rates can be sacrificed, or costs can be sacrificed. This is what public networks do. Not available. LoRa technology is only a physical layer transparent transmission technology. Users can set up their own security engine at the link layer of the network layer, which can carry out the deepest customization, and can also add a hardware encryption chip, which can be analyzed from the data encryption method. See that the safety of LoRa can be strongly guaranteed.

From the analysis of the application layer, users can encrypt according to actual application requirements. Because LoRa has strong flexibility on the networking, the security management methods on the application side can cooperate with the network layer and encryption algorithms to realize the entire application. Overall safety.

In summary, LoRa meets all the requirements of the Ministry of Industry and Information Technology Announcement No. 52:

Limited to small-scale networking applications such as buildings, residential communities and villages;
Transmit on a single channel at any time;
Civilian metering equipment should have anti-interference function;
Avoid interfering with local radio and television stations;
Comply with the emission power limit and emission power spectral density limit;
The duration of a single launch does not exceed 1 second;
The occupied bandwidth is not more than 500kHz.
LoRa is safe. For the physical layer, the LoRa CSS technology can demodulate 20dB below the noise, and it is difficult for ordinary equipment to detect and interfere with LoRa signals. For the network layer, LoRa collects, processes and stores data locally. The data is under the complete control of the network owner and will not leave the private network. For the application layer, the application layer security management can cooperate with the network layer to realize the overall security of the application layer. For Chinese customers who use the LoRaWAN protocol, the LoRaWAN protocol provides strong end-to-end security through encryption at the network layer and application layer.

Xinxie Technology Shenzhen CO. Ltd.

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