The Potential Role of 5.5G in Scaling Passive IoT

Developments in 5G standards are taking us into the technology’s next stage, which Huawei calls 5.5G, progressively introducing a range of new features and functions that make 5G more suitable for industrial Internet of things (IoT) systems. It enables more-sophisticated location services, optimized transmission to balance speed and battery life and the option to use devices that need no batteries at all, known as passive IoT.

Passive IoT, sometimes referred to as ambient IoT, promises to deliver the vision of ubiquitous sensing over 5G infrastructure, as well as other lower-data-rate applications thanks to much-improved energy efficiency and lower costs compared with previous generations of cellular IoT, such as narrowband IoT (NB-IoT) and LTE-M.

As the name implies, passive IoT isn’t connected to an external power supply and doesn’t use batteries. By using cellular transmission and enhancement of receiver sensitivity, passive IoT has a greater range than radio frequency identification (RFID).

Whereas NB-IoT systems typically require battery changes every decade or so, passive IoT systems don’t, mitigating the cost of battery components as well as the associated labour cost of battery replacement. Although a single battery is very small, when scaled up to hundreds of millions of devices the environmental impact is significant. Furthermore, when there’s no need for a battery, sensor size can be reduced.

5.5G passive IoT uses the cellular network, with the end-node devices using wireless electromagnetic energy capture to connect without power cables or built-in batteries. For this the IoT terminal harvests energy from radio waves emitted from the network. This means that the critical factor is the distance between the tag and the base station — the farther the distance, the lower the density of electromagnetic energy and the more difficult it is to obtain energy. The passive IoT concept is already mature and being used for wider scenarios than RFID, with the development of passive IoT over Bluetooth and Wi-Fi-based systems also in progress.

Current uses for passive IoT include automated inventory management, such as real-time tracking of large volumes of objects, with ultralow-cost and battery-less tags. Such applications are widely used in manufacturing, logistics and warehousing industries. Traditionally, paper-printed barcodes, QR codes or RFID tags are used and scanned individually with a hand-held reader, such as an RFID scanner. This is slow and labour-intensive. If these passive IoT tags were scanned using an automated, wide-area remote reading capability, this process could be much faster, although most current network options installed in those environments don’t support this.

However, with billions of IoT end-points currently active, and huge potential for more uses to proliferate, it’s vital to accommodate rapid growth in the number of devices connected. It won’t be enough to rely on existing passive IoT technology options to support this scale or deliver performance improvements. 5G networks can connect over a much greater distance than RFID, and will increasingly be used as infrastructure on large industrial and commercial sites, so could 5G networks support passive IoT applications with lower cost and better performance?

In assessing the potential for 5.5G-based passive IoT, it’s worth noting some of the technology criteria.

Environmental energy harvesting: network connectivity for passive IoT is directly affected by the energy received by each terminal — if some fall below a certain threshold, those terminals become isolated. Harvesting energy to mitigate fragile network connectivity is critical, but must be done in a way that is self-sustainable, eco-friendly (such as by using ambient energy like light, heat, kinetic energy or RF) and works on miniaturized devices with no limits on data transmission periods.

Power usage requirements: energy available for operating passive IoT terminals is limited. Restricting power usage of the driver circuit or chip used for computing is vital — currently, the power consumption of microcontroller chips for low-power computing is at the microwatt level.

Passive IoT terminals: these rely on low-power, low-proximity and low-data-rate communication and reflection of the received RF signal to transmit data.

It’s possible to view the evolution path of passive IoT technology in three stages:

1. A “traditional” RFID or barcode application with point-to-point proximity and read-write architecture. Limitations of the radio systems include self-interference, mutual interference and low efficiency.
2. Site passive IoT, often using RFID tags, which is based on installing multiple antennas on the site and reading local terminals within range. It has improved range over traditional RFID but is still limited to a small site, such as a shop.
3. Cellular-based passive IoT. Using cellular networks can expand the communication distance and support more-complex scenarios of networking application needs, such as the full life cycle management of assets.

Huawei has proposed a passive IoT solution concept based on 5.5G networking that can support transmission distances over 100 metres compared with 10 metres using RFID, by collecting 5G RF energy in specific frequency bands. Within a range of 200 metres, Huawei’s prototype can collect enough power to enable the terminal to communicate with the cellular base station, eliminating the need for a dedicated scanner. 5.5G networks can also improve the recognition rate, coverage and positioning accuracy of passive IoT.

Not only does 5.5G enable passive IoT to be supported on the same infrastructure but the network provides more-intelligent and efficient communication performance. As the supplier ecosystem develops more sensor-type wearables, 5G could be able to enhance consumer IoT across a wide range of applications if the wide-area network is upgraded to support passive IoT.

As the technology and range of products mature, suppliers will need to address important market adoption challenges. Firstly, the use of passive IoT is relatively easy to justify if there’s already a 5G private network in use on the site, but the business case will be more difficult if it’s the driving application.

Secondly, industrial IoT investments are often made under a project budget addressing a specific application, so it can be difficult to justify investment in a general-purpose infrastructure, such as a private network, that supports many uses.

Thirdly, the economics of large IoT systems become governed by the cost and availability of the tags, so it’ll be vital to make 5.5G passive IoT devices competitive with alternative technologies as economies of scale start to be reached.

Typical industrial sensor scenarios such as industrial automation, environmental sensing, intelligent transportation and logistics, smart storage, agriculture, smart cities and security monitoring need thousands of sensors, often in complex and potentially dangerous environments, at very low cost and with very low power usage.

China Mobile and Huawei illustrate the growing market potential with details provided from their installation in a Haier factory in China, making washing machines. Haier has used RFID before and has recently installed a network using 5.5G passive IoT, allowing it to compare the two approaches.

In the factory, the system is being tested to track raw material assets used and containers of components. The two main aims were to improve the visibility of inventory and match data from the factory’s systems more accurately to the actual flow of assets in the factory. The latter has historically been out of sync, which has led to unscheduled downtime of production lines.

With the 5.5G system, Haier achieved continuous coverage in the test areas, totalling 8,000 square metres; has improved inventory tracking from less than 95% accuracy to 99.99%; and is achieving positioning accuracy of less than 10 metres in 90% of instances, making it much easier to find items.

Examples like this show the benefits of passive IoT on 5.5G, and the roll-out of the technology is starting. We’re seeing proof-of-concept systems in use, as well as installations based on prototype network software and terminals. Using 5.5G networks could play a vital role in helping to address the growing potential of passive IoT systems.