“As the Internet of Things has become the third wave of the development of the world’s information industry after computers and the Internet, the boundaries between people and things, and things and things have been continuously extended. The concept of the Internet of Everything has greatly changed people’s existing living environment and habits.
As the Internet of Things has become the third wave of the development of the world’s information industry after computers and the Internet, the boundaries between people and things, and things and things have been continuously extended. The concept of the Internet of Everything has greatly changed people’s existing living environment and habits.
Before the birth of low-power wide area network (LPWAN), IoT scenarios such as smart homes and industrial Internet of Things usually used short-distance communication technologies, such as Wi-Fi, Bluetooth, zigbee, etc.; but for larger-range and long-distance connections, 2G, 3G, 4G, etc. relying on the operator’s network. However, if these wireless communication technologies are distinguished according to the two standards of power consumption and transmission distance, it is found that the technologies that can meet the two characteristics of “low power consumption” and “long distance” at the same time are still lacking. The emergence of LPWAN technology Just make up for this shortcoming.
What is LPWAN?
If you want to transmit information wirelessly over a long distance, you must increase signal power or reduce signal bandwidth. LPWAN, or Low-Power Wide-Area Network, is a long-distance, low-power, low-bandwidth wireless communication network. Most LPWAN technologies can achieve network coverage of several kilometers or even tens of kilometers, solving the problems of high terminal power consumption, massive terminal connections, insufficient wide-area coverage capabilities, and high cost in the Internet of Things industry, and are suitable for large-scale deployment.
LPWAN does not specifically refer to a certain technology, but a combination of various low-power, wide-area network technologies. They generally have the following characteristics:
●Low power consumption: battery life can be as long as 10 years
●Long distance: The coverage is wide, up to tens of kilometers, and the working range in the urban environment is usually more than 2km
●Low data rate: small occupied bandwidth, small amount of transmitted data, low communication frequency
●Insensitive to transmission delay: low requirements for real-time data transmission
●Low cost: Due to the large scale, the deployment cost is low
The above characteristics are the main differences between LPWAN and other wireless network protocols such as Bluetooth, RFID, cellular M2M and ZigBee.
Different technical schools of LPWAN
With the explosive growth of the demand for the Internet of Things, the technical standards of the Internet of Things are constantly escalating, and the competition among the technical genres in LPWAN can be described as extremely fierce.
LPWAN can be divided into two categories: one is LoRa, SigFox and other technologies that work in unlicensed spectrum, which can also be called non-cellular LPWAN; the other is EC-GSM, which uses cellular communication technology based on licensed spectrum and is promoted by 3GPP, LTE Cat.1/0/M1 (eMTC), NB-IoT, etc., can also be called cellular LPWAN. Among the many LPWAN technologies, NB-IoT, eMTC and LoRa are currently the most used and the most controversial. They are often used to compare with each other, but in fact, they are different in technology positioning and application fields.
In the licensed spectrum Internet of Things technology, according to the network rate, high rates can be carried by Cat 4 and above and 5G, low rates can be carried by NB-IoT, and medium rates can be carried by Cat 1 or eMTC.
eMTC is 3GPP’s response to the strong interest in the LPWAN solution, which supports standard LTE connections while preserving resources; NB-IoT is a 3GPP architecture born to challenge the Sigfox and LoRa alliances, which is different from eMTC The point is that it runs outside of the LTE architecture; Cat.1 has been very popular recently, and both it and eMTC can carry the voice after 3G withdrawal, the low-to-medium-rate market, and it lies between the high-speed network (5G and 4G LTE) and low-speed networks. Rate (2G GPRS and NB-IoT) between.
Currently, NB-IoT is mainly promoted in China. This cellular-based narrowband Internet of Things supports software updates to existing cellular infrastructure, such as upgrading existing LTE and GSM base stations. Reusing the existing 2G or 3G spectrum can quickly achieve domestic and international coverage and deployment.
eMTC is an Internet of Things technology based on LTE evolution. It is called Low-Cost MTC in R12 and LTE enhanced MTC in R13. The main features are higher transmission rate, lower delay, support for handover and VoLTE voice communication, and can be applied to scenarios that require higher mobility and transmission rate such as voice calls.
Compared with the two, NB-IoT has a 20dB gain higher than eMTC, which is equivalent to an increase of 100 times the coverage area capacity, and the penetration ability of buildings is also better. It has potential advantages in smart city applications. NB-IoT focuses on small data volume and low-rate applications, and the device power consumption is very small, especially the use of DRX (discontinuous reception) technology, so that the terminal only works when it is needed.
On the other hand, because NB-IoT is a narrowband Internet of Things, although its low-speed characteristics can meet some of the 2G market, it is difficult to meet the needs of 2G/3G voice calls, medium-rate, mobile connections, etc., eMTC/Cat with higher data rates .1 is more suitable for this field. In terms of cost, NB-IoT simplifies radio frequency hardware, simplifies protocols, and reduces baseband complexity, thereby reducing overall component costs. Chip solutions using eMTC/Cat.1 are usually more expensive.
LPWAN technologies that use unlicensed frequency bands include Sigfox, LoRa, Weightless, etc. Due to the use of publicly unlicensed frequency bands, the entry barrier is low, the construction is simple, and the commercialization process is relatively fast.
LoRa is a physical layer of wireless digital communication modulation technology, called spread spectrum continuous frequency modulation modulation technology (Chirp Modulation), its biggest feature is based on the free frequency band of Sub-1GHz, under the same power consumption, compared with the traditional radio frequency communication distance extended 3-5 times, up to 1-20km.
The LoRa terminal can be powered by batteries or other energy harvesting methods, and the battery life can reach 3-10 years. At the same time, the lower data rate of 0.3-50kbps also extends battery life and increases network capacity, realizing the unification of low power consumption and long distance.
LoRa signals are also very penetrating to buildings. Application scenarios include low-power and low-cost sensors in smart agriculture; battery equipment tracking and status monitoring in industrial automation; logistics tracking or positioning. LoRa communication is compared to NB when moving at high speeds. -IoT is more stable.
Although SigFox also uses unlicensed spectrum, it has a strong ecosystem among foreign operators. Its promotion in Europe is very successful. It also has its own base stations worldwide. It currently has networks in nearly 60 countries/regions around the world.
SigFox works in the ISM frequency bands of 868MHz and 902MHz and consumes very narrow bandwidth or power consumption. Therefore, it is suitable for systems that only need to send a small amount of infrequent data bursts, such as parking sensors, water meters and smart trash cans. The disadvantage is that it will be severely restricted when data is sent back to the sensor/device (downlink capability), and there will also be signal interference issues.
Both LoRa and Sigfox have the characteristics of long distance and low power consumption, which can extend battery life and realize large-scale information transmission, and both use the unlicensed Sub-1GHz ISM frequency band without additional licensing fees. Both LoRa and Sigfox have a limit on the number of daily transmissions, which are suitable for use in areas where there is no need for real-time communication.
Ingenu (previously known as On-Ramp Wireless) has developed a two-way solution based on years of research and realized a proprietary direct sequence spread spectrum modulation technology called RPMA (Random Phase Multiple Access), the design purpose of RPMA It provides high-capacity, safe and wide-range interconnection solutions in the 2.4GHz frequency band.
In the United States, a single RPMA access point can cover an area of 176 square meters, which is much larger than the Sigfox and LoRa standards. It has minimal overhead, low latency and broadcast functions, and can send commands to a large number of devices at the same time. However, the hardware, software and other functions are limited to those provided by the company, and it is necessary to build its own public and private networks dedicated to machine-to-machine communication.
Link Labs is a member of the LoRa Alliance, so it uses LoRa chips. However, Link Labs did not use LoRaWAN, but built a proprietary MAC layer (software) on top of Semtech’s chip called Symphony Link.
Compared with LoRaWAN, Symphony Link adds some important connection features, including guaranteed message reception, wireless firmware upgrades, deletion of duty cycle limits, repeater functions, and dynamic range.
Weightless SIG (Special Interest Group) was established in 2008 with a mission to standardize LPWAN technology. Weightless SIG is the only truly open standard that can operate in the sub-1GHz unlicensed spectrum. There are three versions of Weightless that can be used for different purposes:
Weightless-W: Take advantage of white space (local spectrum that is not used in the licensed TV band)
Weightless-N: License-free spectrum narrowband protocol born from NWave technology
Weightless-P: A two-way protocol born of M2COMM Platanus technology
Among them, Weightless-N and Weightless-P are more popular because of the shorter battery life of Weightless-W.
Nwave’s Weightless-N is very similar in function to SigFox, but has a better MAC layer implementation. It claims to use “advanced demodulation technology” to enable its network to coexist with other radio technologies without generating additional noise. Like SigFox, it is most suitable for sensor-based networks, temperature readings, tank level monitoring, smart metering and other such applications.
The Weightless-P standard uses FDMA + TDMA modulation (larger than SigFox but smaller than LoRa) in the 12.5 kHz narrowband. It also has an adaptive data rate, similar to Symphony Link (200 bps to 100 kbps). The sensitivity is very high, -134 dBm at 625 bps, and supports PSK and GMSK modulation. For private networks, more complex use cases and situations where controlling uplink data and downlink data is very important, Weightless-P makes sense. The Weightless-P development kit has only just begun to go on the market.
LPWAN technology deployment status of different factions
According to the IoT and LPWAN deployment tracking report released by the research institute Ovum in the fourth quarter of 2019, including licensed spectrum and unlicensed spectrum, the total number of announced LPWAN deployments worldwide has reached 501.
LoRa for unlicensed spectrum is still the most used technology in existing networks, and it occupies a dominant position in commercial existing network deployments, accounting for almost one-third of the market share (about 30.3%). However, NB-IoT has gradually approached, ranking second, with 89 commercial networks as of the end of the third quarter of 2019.
Despite the growth in licensed spectrum LPWAN deployment, LoRa is expected to maintain its leading position. LoRa chipset provider Semtech stated in a briefing at the end of last year that it now has 14 national public LoRa networks in 10 countries/regions, and there are 50,000 LoRa technology developers worldwide. The technology has more than 100 million terminal nodes (including private networks) and is supported by 120 service providers worldwide.
In terms of licensed spectrum technology, many CSPs are now adopting dual technology strategies, while providing NB-IoT and LTE-M networks. But in terms of network deployment, NB-IoT is still far ahead of LTE-M, and the number of commercial network deployments is three times that of LTE-M. The lower module cost makes NB-IoT (or indeed 2G or 3G cellular networks) a more attractive solution.
NB-IoT or LTE-M Internet of Things roaming has important advantages for asset tracking and other applications, because asset tracking may require network connections across multiple countries/regions, but the problem of LPWAN roaming in licensed spectrum has always restricted the development of the market. The inability to roam means that the deployment of licensed spectrum LPWAN IoT terminal equipment in multiple countries/regions requires multiple contracts with different operators and may need to deal with multiple different management systems. However, this situation has also changed in recent years.
Who will win in China?
In China, the dispute over various LPWAN technologies can be simply seen as a competition between licensed spectrum (represented by NB-IoT) and unlicensed spectrum (represented by LoRa). Although both parties indicated that they serve different markets and there is no competition, In the emerging field of the Internet of Things where a communication standard has not yet been selected, they are striving for it.
On December 13, 2017, the Radio Regulatory Bureau of the Ministry of Industry and Information Technology issued the “Technical Requirements for Micropower Short-Range Radio Transmission Equipment (Draft for Comment)”. At the same time, my country completed the complete submission of IMT-2020 (5G) candidate technical solutions, including NB-IoT The technology is officially included in the 5G candidate technology set.
LoRa does not have an authorized frequency band in my country, and in November 2019, the Ministry of Industry and Information Technology of the People’s Republic of China issued the “Announcement No. 52 of the Ministry of Industry and Information Technology of the People’s Republic of China” to further regulate the management of micro-power short-range radio transmission equipment. Many people interpret that LoRa will be fully replaced by NB-IoT in China. For this reason, the chip manufacturer Semetech specially issued an article to interpret this announcement, stating that LoRa meets all the requirements of the Ministry of Industry and Information Technology Announcement No. 52. (For detailed interpretation, please refer to the article “About LoRa and Ministry of Industry and Information Technology Document No. 52, this article answers all questions” https://www.eet-china.com/news/202007311648.html)
In terms of chip development and supply, Semetch (International) AG is a Swiss company headquartered in Rapperswil, Switzerland. The manufacturing, assembly and agency distribution of LoRa chips are carried out in Asia. In addition, Semtech has licensed certain manufacturing rights for its LoRa technology to certain semiconductor companies in Europe and Asia.
There are no restrictions on the NB-IoT chip, and everyone can do it. Currently, it is mainly LED by companies such as Huawei HiSilicon, Ziguang Zhanrui, and MediaTek. Due to the aura of the national Internet of Things strategy, since the establishment of the 2017 standard, operators have successively issued subsidy policies for NB-IoT modules. At the beginning of April this year, China Telecom announced the results of the 2020 NB-IoT IoT module centralized procurement project. The average price of the winning bid was 14.5 yuan, of which the lowest price was 13.47 yuan and the highest price was 14.8 yuan. In July, some module manufacturers even quoted a price of 9.9 yuan.
The rapidly growing network market size is the main reason for the decline in the price of NB-IoT modules. When operator subsidies stimulate more operators to join, the scale of the supply side becomes larger, and the price of upstream chips will first come down, and then downstream will also lower prices. In this regard, it is more beneficial to the popularization of NB-IoT and speeding up the transfer of 2G users. However, if end users blindly demand lower prices, manufacturers in certain links of the supply chain may not be able to make money, and there will be a situation in which “the NB-IoT camp has not started to fight against the unlicensed spectrum, and the NB-IoT camp will kill a group of teammates first in a price war.” .
Compared with eMTC and NB-IoT, Cat.1 has greater opportunities in China, because Cat.1 is a branch of the 4G network, and operators can complete the network deployment with the help of 4G base stations without increasing investment. While eMTC requires infrastructure construction, and operators are now investing more resources in 5G construction, it is difficult to have excess funds invested in eMTC.
Compared with NB-IoT and 2G, Cat.1 also has advantages in network coverage, speed and delay; compared with eMTC modules, it has the advantages of low cost and low power consumption, and has the same millisecond transmission delay. It is considered to be the best technology to fill the 2G/3G withdrawal.
After discovering that the application scenarios of NB-IoT were narrow and unable to replace all 2G/3G network markets, the three major operators also carried out Cat.1 network deployments, which even weakened the position of NB-IoT. This is also related to the fact that operators have not yet found a good NB-IoT business model. The profit model of operators needs to be further explored. Users in vertical industries need to explore business cooperation charging models with operators.
Complementarity and coexistence
From the perspective of evolution, the current trend of IoT access technology towards low power and wide coverage has become increasingly obvious. Although some people say that after the popularization of 5G, its characteristics of low latency, low power consumption and high data transmission rate are expected to shake up the entire LPWAN pattern, it is said that 3GPP is also considering allowing 5G technology to be used in unlicensed frequency bands (especially 3.5 GHz, 5 GHz and 60 GHz). ), which has a great impact on unlicensed LPWAN. However, the author believes that the high tariffs and inflexible deployment of 5G are determined based on the operator’s network. Especially users who want to ensure that their data stays locally and are safe and controllable will still adopt self-organizing networks in a small area.
Various LPWAN technologies have their own characteristics and mature markets. Take NB-IoT and LoRa as examples. Both have common LPWAN technical characteristics such as low power consumption, wide coverage, and low cost, and NB-IoT has a larger bandwidth. , Higher reliability, capable of global roaming, and more suitable for large network coverage, while LoRa has lower power consumption, easier deployment and lower cost, and is more flexible to meet the application needs of diverse scenarios.
Any kind of Internet of Things technology has the most suitable application scenarios, so there is no perfect technology, only the most suitable choice, even the three major operators will choose hybrid networking based on actual conditions. From the perspective of technology and application, although authorized and unlicensed LPWAN technologies will compete in certain areas in the future, they will generally focus on “complementarity” and “coexistence” rather than “replacement.”