Passive IoT technology can indeed cover hundreds of billions of IoT nodes. The industry’s research on passive IoT has been ongoing. It is extremely challenging to support passive IoT on 5G cellular networks. The subject also extends 5G connectivity to a wider range of the physical world.
A cellular network connects hundreds of billions of terminals, the key point is the passive IoT
The 5G network also needs to be continuously enhanced to better support the Internet of Things and to meet the demand for carrying hundreds of billions of connections in the future. This requires 5G networks to support IoT types with different speed gears to match the differentiated needs of the industry;
In addition, a large number of current IoT applications are based on passive connections. How improve the recognition rate, coverage, and positioning accuracy of passive IoT through networked technologies is the future innovation direction of 5G networks. This requires industry partners to jointly define standards and Build an industrial chain.
The cellular network’s support for the Internet of Things is mainly divided into three different speed gears, namely high-speed IoT, medium-speed IoT, and narrowband IoT. The high-speed IoT is mainly carried by 4G Cat.4+ and 5G eMBB. Suwulian is currently mainly carried by 4G Cat.1, and narrowband IoT is mainly carried by NB-IoT.
NB-IoT for low-speed Internet of Things is facing nearly tens of billions of low-power Internet of Things nodes; the scale of Internet of Things connections that can be brought about by medium-speed and high-speed cellular networks is much lower than that of low-speed Internet of Things.
Therefore, relying on these 3 different speed gears of cellular network technology can only support 10 billion-level Internet of Things connections.
NB-IoT is aimed at a large number of scenarios where only low-frequency and small data packets are sent but the power supply is inconvenient. Water and gas meters, environmental monitoring, fire smoke detection, etc. are all scenarios where NB-IoT can play a role, but the NB-IoT module is still A small battery needed to supply power. Through a low-power design, the battery can be replaced for several years or even 10 years, achieving the goal of not needing to be on duty.
However, there are still a large number of physical terminals due to their own conditions, which may not even have the conditions for a small battery power supply or have low-cost restrictions, such as some fast-moving consumer goods, logistics packages, product packaging, warehouse goods inventory, etc. It constitutes a hundred billion-level passive IoT node.
For example, it is obviously unrealistic to use NB-IoT-like solutions for tens of billions of clothing, shoes, hats, and express parcels every year, and a passive IoT solution is needed.
The passive Internet of Things is inspired by the massively used and mature RFID tags. In the past decade or so, RFID technology has been widely used in retail, medical, logistics, manufacturing, and other industries, and tens of billions of connections can be added every year.
The British market research company IDTechEx has released data showing that the global sales of RFID tags reached 21 billion in 2019, compared with 17.5 billion in 2018, and most of the growth in sales comes from passive RFID tags. It can be seen that passive RFID tags can easily reach hundreds of billions of connections.
RFID itself has some limitations, such as short transmission distance and high dependence on dedicated readers. If cellular networks can support passive IoT, these limitations must be broken and cellular networks’ support for the Internet of Things must be expanded.
Huawei proposes the direction of Passive IoT in the 5.5G vision, which is to expand the transmission distance of the scene supported by RFID from 10 meters to 100 meters, and cut off the dedicated reader so that the terminal can directly transmit back to the cellular gateway. node.
In April 2021, 3GPP officially confirmed the name of 5G evolution as 5G-Advanced and decided that 5G-Advanced will start from R18.
In July 2021, 3GPP organized a seminar on potential research directions for R18. There are many enhancements to the Internet of Things. If Passive IoT can be included in R18 research projects, it will have a greater social effect than NB-IoT in a few years.
Research and development for passive IoT technology has been ongoing
To support passive IoT through 5G cellular networks, one difficulty is how passive terminal nodes obtain energy, and the other difficulty is how to achieve long-distance backhaul, especially the latter is more difficult.
Because the energy obtained by the passive terminal through various methods is very weak, the return path is too long, and the signal will quickly decay. In fact, in the past few years, the industry has conducted a lot of research on this and achieved many results. Therefore, it is also possible for 5G cellular networks to support passive IoT.
Representative ones include:
Passive IoT based on Bluetooth
A start-up company called Wiliot, the company’s most typical product is a passive Bluetooth low energy sensor tag. The biggest highlight of the tag is that it does not require a power supply. The energy for sensing, storage, and communication comes from collecting the surrounding radiofrequency. Energy to power it, and use the energy to send the data of the tag’s unique identification code and sensor readings.
With this design, the label does not require a battery, so its size can be designed to be the size of a postage stamp, and it can be easily pasted on various items.
Not only Bluetooth radio frequency signals can be used as the energy source of Wiliot tags, but also wireless radio frequency signals such as Wi-Fi, cellular, and LoRa can drive its self-powered. Its technology completes the difficulty of obtaining energy for passive nodes.
Its transmission distance is 3 meters, and a transmission distance of 10 meters will be realized in the future. This is because Wiliot backhaul is mainly through low-power Bluetooth, so it cannot solve the problem of long-distance backhaul.
Passive IoT based on WiFi
Researchers from the School of Electronic Engineering at the University of Washington in the United States proposed a reflection modulation technique for radio frequency signals to realize power supply and data transmission for passive devices.
As early as 2016, researchers from the college developed a brand-new WiFi technology called Passive WiFi. Its design principle is similar to that of an RFID chip. It uses the retroreflective communication technology of radio frequency signals. After the router transmits a relatively high-power radio frequency signal, the passive IoT node absorbs the radio frequency signal and modulates the antenna reflection coefficient to transmit sensor information.
Passive WiFi passive nodes consume only 14.5µW and 59.2µW when transmitting 1Mbps and 11Mbps, which are only one ten-thousandth of the power consumption of normal WiFi nodes and one-thousandth of the power consumption of Bluetooth and Zigbee nodes and can be achieved.
With a return distance of 30 meters, it even has a certain ability to penetrate walls. Therefore, this type of technology can to a large extent extend passive WiFi to scenes that cannot be covered by the original WiFi tens of times.
Wide-area passive IoT based on LoRa
If the above two types of technologies are more focused on the passive IoT access research of short-distance communication technology, then the passive IoT access research of long-distance communication technology has more reference for the support of passive communication in the cellular Internet of Things significance.
In 2017, a research team from the School of Electronic Engineering of the University of Washington in the United States explained in a paper that it extended the reflection modulation technology to long-distance transmission systems.
If the long-distance transmission is to be carried out, one of the biggest difficulties that need to be overcome is the problem of the weak return signal from passive nodes, because the return signal is inversely proportional to the square of the distance from the RF transmitter to the node and the distance from the node to the receiver. When the distance is far enough at that time, the signal that needs to be transmitted after reflection modulation is even one million times weaker than the signal transmitted to it by the radio frequency source.
Researchers use linear spread spectrum technology to improve passive tag return capability, and it is compatible with commercial LoRa equipment to form a LoRa-based reflection modulation system.
In the test, the researchers successfully achieved passive node reflection modulation from any position separated by 475 meters between the RF source and the receiver, and successfully returned sensor information;
When the passive node and the radio frequency source are located at the same location, the receiver can reach a maximum distance of 2.8 kilometers, realizing long-distance transmission. In this process, the power consumption of the node is only 10µW, and when this system is mass-produced, it is estimated that the cost of each node label is only 10-20 cents.
In terms of passive cellular IoT support, there have also been some explorations. Based on reflection modulation, the compatibility of UHF RFID with cellular networks has been studied, and the design scheme of passive cellular IoT systems has been proposed, including cellular IoT base stations and passives; Terminal software and hardware architecture, and compatibility of mainstream benefits.
Although it is still a theoretical study, it can be seen that the research of cellular networks supporting passive IoT has also been put on the agenda, and the research direction of 5G supporting passive IoT access also has a certain foundation.
In the past development of the Internet of Things, the passive Internet of Things seems to have no intersection with the cellular network. Today, the vision of allowing 5G to carry hundreds of billions of Internet of Things access is indispensable for passive IoT support. Driven by this goal, cellular mobile communication networks are closely integrated with passive IoT for the first time and become the largest group in 5G connections future.
You may also be interested in the below articles.
