Battery-Free NB-IoT and LoRa: New Opportunities for LPWAN!

Author: Zhao Xiaofei

IoT Think Tank Original

Introduction

With the further development of environmental energy harvesting technology, passive IoT technology can not only provide energy sources for backscatter communication nodes that require only microwatt-level power consumption, but also support NB-IoT, LoRa, and other low-power wide-area network (LPWAN) terminals in certain scenarios, allowing previously battery-dependent nodes to completely eliminate batteries and achieve a longer lifespan.

Passive IoT has become a hot topic in the industry. With the ongoing research and discussions on 5G Advanced and 6G, passive IoT is also a key research topic for future upgraded versions of 5G and 6G, bearing the task of supporting massive nodes and even connecting billions. Research on passive IoT focuses on energy harvesting, low-power communication, low-power computing, and low-power sensing, with the first two being the main focuses. The mainstream technologies are environmental energy harvesting and backscatter communication technology.

As environmental energy harvesting technology continues to advance, this technology not only provides energy sources for backscatter communication nodes with microwatt-level power consumption but also supports NB-IoT, LoRa, and other LPWAN terminals in certain scenarios, allowing previously battery-operated nodes to completely eliminate batteries and achieve a longer lifespan.

Low Power Consumption is a Main Line in IoT Development

Reducing the power consumption of terminal nodes has always been one of the core themes in IoT development. Over the past decade, numerous technological innovations have significantly reduced the power consumption of IoT nodes, making it one of the most关注的领域 in the IoT industry. It can be said that low power consumption is a main path for IoT development.

Taking cellular IoT as an example, as early as 2009, 3GPP defined the LTE Cat.1 standard for low-power cellular IoT access terminals in its R8 version standard. After years of development, Cat.1 has become one of the main forces in cellular IoT. More attention-grabbing is NB-IoT, which launched its first standard in 2016, with its biggest selling point being further reduced power consumption, allowing battery-powered operation for 5-10 years in specific scenarios; recently, 5G R17 is about to be frozen, with RedCap (Reduced Capability Terminal) attracting much attention, which also significantly reduces the power consumption of 5G IoT terminals.

In the non-cellular IoT field, the most typical low-power wide-area network technology, LoRa, has also become a hot topic in IoT in recent years, supporting a large number of low-power sensor terminal access. The local IoT field has also made reducing power consumption one of its core technological paths. For example, Bluetooth highlights low power consumption with each new generation of technology, and the WiFi Alliance has introduced a dedicated low-power standard, WiFi Halow, to support massive nodes accessing via WiFi.

These various low-power technologies and standards have greatly expanded the scope of IoT connectivity. In recent years, among the newly added IoT connection nodes, those using low-power technologies account for the largest proportion, indicating that low power consumption has become the absolute main force in IoT connectivity. However, existing low-power technologies still require various forms of active power supply for IoT nodes. Although most only need standard batteries or button batteries, many scenarios do not have the conditions for battery power supply, or the lifecycle of the scenario exceeds the battery lifespan, resulting in high maintenance costs. These are the scenarios that passive IoT needs to support.

Currently, the low-power wide-area networks that are commercially available on a large scale are mainly represented by NB-IoT and LoRa, with related nodes powered by batteries. However, the industry has begun to explore their passive upgrade, providing energy support for NB-IoT and LoRa nodes through environmental energy harvesting technology, achieving battery-free, maintenance-free, and permanent power supply, thereby expanding the application range of NB-IoT and LoRa and reducing costs in many scenarios.

Passive Upgrades for NB-IoT and LoRa are Underway

According to publicly available information, the exploration of passive upgrades for NB-IoT and LoRa is already underway, with some small-scale implementations. This is mainly focused on self-sufficient modules formed by combining environmental energy harvesting technology with NB-IoT and LoRa, where environmental energy harvesting solutions are primarily provided by some startup companies.

As early as 2019, HiSilicon Semiconductor collaborated with a Dutch energy management chip company, Nowi, to launch an energy self-sufficient NB-IoT platform, achieving a second-generation upgrade in 2020. This platform is based on HiSilicon’s Hi2115 NB-IoT solution and Nowi’s NH2 energy harvesting power management chip, providing long-term power supply for chips and modules through energy harvesting, supporting NB-IoT transmission. Nowi is a startup focused on energy harvesting management, with core technology in environmental energy harvesting management, aiming to provide a “Plug & Forget” power supply solution for low-power connectivity applications.

In January 2021, a Belgian semiconductor startup named e-peas collaborated with cellular chip manufacturer Sequans to launch a self-sufficient LTE-M/NB-IoT solution. This solution uses e-peas’s energy harvesting management IC and Sequans’s Monarch LTE-M/NB-IoT chip, with e-peas’s energy management IC transferring energy harvested from photovoltaics to storage components, then supplying power to Sequans’s LTE-M/NB-IoT components. The demonstration kit launched by both parties includes a small indoor photovoltaic battery unit, which can use indoor lighting as an environmental energy source.

In April 2021, Japan’s Murata collaborated with Nowi to launch a battery-free LoRa solution reference platform. This platform uses Murata’s LoRa module and is powered by Nowi’s energy harvesting power management (PMIC) chip, which supplies energy to Smtech’s LoRa transceiver and STMicroelectronics’s MCU. Under this reference platform, battery-free low-power wide-area network nodes can be deployed on a large scale in some scenarios.

During this year’s MWC, Murata, Deutsche Telekom, and Nowi collaborated to launch the “Energy Autonomous Cellular IoT Development Solution,” known as the Autonomous NB-IoT Development Solution (ANDS), claiming to be the world’s smallest energy harvesting NB-IoT module. In this solution, Murata provides its small-sized 1YS NB-IoT module, Deutsche Telekom’s nuSIM is directly integrated into Murata’s module, and Nowi provides its NH2 energy harvesting chip, which is 3x3mm in size and can provide permanent power for the solution. This solution encompasses wireless communication, power management, and SIM management.

The author learned that a domestic passive IoT company named Feiying SiTe is also collaborating with relevant IoT module manufacturers to provide energy for NB-IoT modules through its micro-energy management module, supporting battery-free operation of NB-IoT in some scenarios.

Currently, NB-IoT and LoRa have formed a connection scale of over 100 million, widely distributed across multiple scenarios. If passive technology can mature, it will further expand the application scenarios of NB-IoT and LoRa, opening up new market space for them.

Further Breaking the Barriers of Passive NB-IoT and LoRa

Currently, low-power wide-area network terminal nodes generally use battery power to drive their operation, basically meeting the power supply needs of smart water meters, smart gas meters, smart smoke detectors, smart tracking and positioning, and other terminal lifecycles. However, there is still significant demand for passive low-power wide-area network terminals. In the author’s view, these demands are mainly reflected in the following two aspects:

(1) Technologies like NB-IoT and LoRa are suitable for certain scenarios’ communication technology needs, but the battery power supply cycle is shorter than the lifecycle requirements of terminal nodes in those scenarios, resulting in maintenance costs such as battery replacement;

(2) Backscatter communication technology is still in the early stages of commercialization, with limitations in communication distance, throughput, security, and other aspects, leading to limited applicable scenarios.

Taking NB-IoT as an example, although NB-IoT has significantly reduced power consumption compared to LTE, and introduced eDRX and PSM power-saving modes to further decrease terminal energy consumption and extend battery life, the actual deployment scenarios vary greatly in terms of environment and business models. Standard batteries may not support the claimed 5-10 year cycle, and using larger capacity batteries increases costs and terminal size, hindering rapid deployment. For example, for positioning terminals for livestock like cattle and sheep, especially for large herds or free-range livestock, the complex environment often leads to power consumption exceeding theoretical levels, necessitating battery replacements during the livestock growth cycle.

However, technologies like NB-IoT and LoRa are currently mature for large connections and long-distance IoT communication, making them very suitable for supporting data backhaul from sensing nodes in these scenarios. Currently, the mature backscatter communication technology only has a communication distance of about 10 meters and very low transmission rates, with related performance unable to replace NB-IoT and LoRa technologies. Thus, NB-IoT and LoRa remain the preferred choices for some low-power wide-area scenarios. At this point, battery-free power supply technologies are needed to support NB-IoT and LoRa terminal nodes to operate for longer periods at lower costs, making environmental energy harvesting technology essential.

The author previously summarized environmental energy harvesting in the article “Far Below NB-IoT Power Consumption, Passive IoT is the ‘Killer’ for Achieving Billions of IoT Connections!” This technology can enable IoT terminal nodes to break free from battery concerns and achieve long-term power supply. However, supporting NB-IoT and LoRa nodes with environmental energy harvesting technology faces significant challenges, primarily due to the very weak energy harvested through environmental energy harvesting technologies, requiring extensive technical optimization to meet the communication needs of NB-IoT and LoRa nodes.

Experts Zhang Xiaohan and others from the Beijing Institute of Nano Energy and Systems, Chinese Academy of Sciences, summarized the energy density that typical environmental energy harvesting technologies can obtain as follows:

It can be seen that typical environmental energy harvesting technologies such as solar energy, thermoelectric energy, radio frequency energy, and vibration energy mostly harvest energy densities at the microwatt level, while the transmission and reception power of NB-IoT and LoRa modules are at the milliwatt level, especially with the maximum power for sending data reaching hundreds of milliwatts. The weakness and randomness of the energy harvested through environmental energy harvesting pose significant challenges for driving NB-IoT and LoRa modules.

Therefore, environmental energy harvesting technology should not only focus on energy harvesting, but also on the management and storage of the weak energy harvested, which is particularly important for energy management. This is because the energy harvested from solar, thermal, vibration, and radio frequency sources is relatively weak and unstable, requiring effective integration of energy management technologies to power nodes or store energy in energy storage units for continuous supply.

Currently, many emerging passive IoT companies are making energy management their core technology, continuously enhancing the efficiency of managing the weak energy harvested, such as by employing optimized Maximum Power Point Tracking algorithms. The author has communicated with the Feiying SiTe team and learned that they have tried hundreds of combinations to achieve a low-power micro-energy management architecture with seven module combinations for better micro-energy management efficiency.

The progress in energy harvesting technology, especially micro-energy management technology, provides solutions for the passive upgrades of NB-IoT and LoRa. The micro-energy management field has also attracted numerous companies to enter, including traditional semiconductor manufacturers such as Texas Instruments and Analog Devices, who are also placing great importance on improving micro-energy management technologies and products. Of course, there is also the perennial factor of cost; when energy harvesting series technologies support self-sufficient solutions that can significantly undercut existing battery-powered solutions, it is believed that many scenarios will favor NB-IoT and LoRa solution providers, greatly expanding the market space for NB-IoT and LoRa.

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