Could Passive IoT Be the Killer App for 5G-Advanced?

Passive or ambient Internet of Things (IoT) is a new concept being discussed in The 3rd Generation Partnership Project (3GPP), aiming to connect sensors and devices to cellular networks without a power source. In 3GPP Release 18, which is currently underway, there have been several study items and contributions that aim to specify passive IoT, before the official standardization work—as part of Work Items—begins in Release 19, which aims to be complete by 2025. According to Huawei, which positions passive IoT as a core part of its 5G-Advanced story, and other vendors, the new concept will likely reach pre-commercial status by the end of 2024. Huawei introduced the concept to 3GPP as part of a proposal submitted to the group in June 2021, but a much broader group of vendors are now involved, including MediaTek, OPPO, Nokia, Qualcomm, as well as operators KPN and Vodafone.

Passive IoT could be considered both groundbreaking and promising—contrary to many other radical concepts that have been introduced in 3GPP, but never materialized due to lack of market traction or vendor buy-in. In passive IoT, there are two types of sensors according to Huawei:

• Passive sensors have no energy storage or any form of signal generation. These sensors could be considered similar to Radio Frequency Identification (RFID). According to early tests performed by Huawei, the range of these sensors could be 18 Meters (m) in an indoor environment or 270 m in a Line-of-Sight (LOS) connection. The cost of passive sensors is estimated to be US$0.05 in large quantities and the nominal power profile is estimated to be 1 μW to allow for communication.
• Active sensors harvest energy from ambient sources and include active components for signal transmission. The typical range of these sensors is 500 m according to early tests and the expected cost is US$0.5 with a nominal power profile of 500 μW.

Several companies are already conducting tests and trials with both passive and active sensors, but the target prices above require significant scale. Nevertheless, passive IoT provides two significant advantages over competing technologies.

The new technology competes head on with RFID, essentially aiming to complement it, or even replace it. The range of passive RFID goes up to a few meters at best, which translates to a requirement for multiple mobile readers. On the other hand, even if passive IoT does not deliver the range it promises, it will still provide better performance compared to RFID. Regardless, passive IoT holds a significant advantage over RFID.

RFID is deployed for one purpose alone, to identify and track tags. On one hand, passive IoT will use existing cellular infrastructure, most likely in-building wireless systems, to enable the very same feature with a potentially higher range. One the other hand, the major advantage of passive IoT is that it will also allow for 5G connectivity in the same area and will enable a plethora of new applications and use cases—not only identification and tracking. This may well be the killer application for 5G-Advanced (3GPP Release 19) and the vehicle through which enterprise 5G reaches significant scale.

However, the deployment of passive IoT will not come without challenges. For one, the spectrum in which it will be deployed needs to be lower frequency than in-building wireless and private 5G networks. Energy harvesting and low-power sensor communication need frequencies well below 1 Gigahertz (GHz), perhaps as low as 400 Megahertz (MHz) to 500 MHz, which may be a complication when most indoor systems need higher frequencies for wider bandwidth. Moreover, other 5G-Advanced concepts, such as Sidelink, operate on higher frequencies, making the coexistence and cooperation of those with passive IoT something to be developed further. To summarize, passive IoT has its challenges, but introduces significant opportunities.

Passive IoT doesn’t come without challenges though, especially when the cost to deploy cellular infrastructure in an enterprise location will likely cost significantly more than RFID, and passive IoT tags will still need to reach economies of scale to approach the cost of RFID tags. This will actually be a make-or-break factor for the new concept; if sensors—both passive and active—will not reach the levels announced by Huawei, then the new technology will not likely be considered outside niche use cases.

However, if passive IoT sensors do reach the price levels above, which could be a tangible target when passive RFID tags cost ~US$0.1, then the new concept could increase the number of cellular IoT devices exponentially. If this happens, enterprise 5G will also appeal much more to several enterprise verticals. A large number of enterprise 5G deployments will, in turn, create a thriving application and use case ecosystem, which may deliver on the original promise of 5G—to be enterprise focused. Several vendors are now pushing for this development in 3GPP and if the industry rallies behind this functionality, 5G-Advanced may experience a turning point in the enterprise domain in the next few years.