Rethinking Connectivity for Massive IoT

For decades, SIM cards have served mobile phone users well, enabling easy switching between devices. But in the world of Massive IoT, where millions of devices operate under severe constraints of bandwidth, latency, and power, traditional SIM management methods are no longer sufficient.

While transforming how we think about connectivity at scale, Massive IoT also makes it clear that traditional SIM cards are no longer practical for devices operating under strict constraints. Given that these devices often operate in hard-to-reach areas and need to stay connected without using much energy, eSIMs offer clear benefits with no requirement for physical swap and enabling remote profile management.

Using eSIMs in the context of Massive IoT also comes with its own challenges however, particularly around latency and profile switching. Thankfully, there are a number of network technologies and operating methods being developed to address these challenges.

Massive IoT is reshaping the economics of connectivity: billions of devices, each consuming only a few kilobytes of data and pennies of revenue, are redefining how operators manage identity and scale.

Managing eSIM Profiles in Massive IoT

Massive IoT presents unique challenges for eSIM lifecycle management, particularly around minimising power consumption while retaining the ability to switch connectivity providers. This makes it critical that management mechanisms are adapted to suit constrained devices. The GSMA’s specific standards, SGP.31 and SGP.32, which allow profile management over several protocols, define a modern framework for eSIM profile management in IoT.

When implemented over efficient protocols like LwM2M and CoAP, these standards enable network operators and enterprises to maximise device lifespan, reduce costs, and retain flexibility in managing connectivity throughout the device lifecycle.

The Latency Trade-Off

In typical Massive IoT deployments, eSIM profile changes are often only once or twice over a device’s lifetime. As a result, devices should avoid maintaining constant connectivity to conserve power. In devices with SMS support, servers can use SMS wake-up messages to request a connection. 

However, many Massive IoT devices don’t support SMS and often remain offline for extended periods due to Power Saving Mode (PSM) or extended Discontinuous Reception (eDRX).  This introduces a latency challenge: if a server requests a profile change, it may have to wait hours or even days until the device next connects.

Managing this latency-power trade-off is critical for efficient eSIM management in Massive IoT. However, there are several techniques that can help with this:

• Use of IPv6: IPv6 allows for globally unique, persistent addresses, which can improve addressability across power cycles. In contrast, IPv4 addresses often change, especially in low-cost M2M deployments.
• LwM2M-Based Addressability: LwM2M supports observation and notification models that allow devices to pull configuration updates upon waking. It also supports registration-based events, allowing the network or server to act when a device reconnects.
• Network-Assisted Triggers: Instead of polling, the mobile network can inform the eSIM IoT Remote Manager (EIM) when a device becomes available. The EIM can then initiate profile management workflows while the device is online.

NB-IoT’s Role in Massive IoT Deployment

While IoT is expanding rapidly, with billions of devices coming online every year, not all IoT devices are created equal. Some are high-powered, data-hungry machines while others are small, low-power sensors that need to run for years on a tiny battery. However, on the other hand, the Massive IoT device category refers to very large numbers of low-cost endpoints with limited processing power and memory, which typically means restricted bandwidth.

These devices are built to last (often up to 15 years) whether they’re connected to mains electricity or not. They’re also expected to be deployed in less constrained ways compared to other cellular types, meaning they may be located far from radio towers. This means they need specific network technologies and operating methods to support these conditions, and that’s where Narrowband IoT (NB-IoT) comes in.

NB-IoT, a cellular communication technology standardised by 3GPP and designed specifically for Massive IoT deployments, enables millions of simple, cost-effective devices to connect over long distances, even in hard-to-reach locations like basements, rural areas, or deep indoors. 

For example, NB-IoT uses half-duplex transmission, meaning that a device can only send and receive data in one direction at a time. It also allows devices to switch off their radios to save power and computing resources, only turning them on when needed. These features power a new range of IoT applications but do introduce technical challenges for bandwidth and latency.

Protocols That Support NB-IoT Constraints

To address these limitations, a range of protocols has been introduced and extended. Examples include the Constrained Application Protocol (CoAP), MQTT for sensor networks (MQTT-SN), and the Lightweight Machine-to-Machine Protocol (LwM2M). These protocols include many optimisations for the constrained nature of the network and the devices that they use. 

The features vary from protocol to protocol, but they include things such as tokenising variable names, procedures for going offline while retaining device state, and the ability to exclude confirmative messages. One main feature common to all of these protocols is that the binding to the lower layers can use the User Datagram Protocol, which is much ‘lighter’ than the alternatives in terms of payload and latency.

These protocols help overcome the limitations of traditional SIM management, support large numbers of devices that use minimal data and power, using communication methods that allow devices to sleep most of the time to conserve energy, while still being able to send and receive data when needed. 

However, it is essential to understand that while NB-IoT trades speed for efficiency and coverage, it also introduces constraints around latency, throughput, and power consumption. That’s where the choice of communication protocol (MQTT, CoAP, LwM2M, etc.) becomes critical as not every protocol is equally well-suited.

Building the Future of Scalable IoT

NB-IoT is not about high-speed data, it’s about scale, efficiency, and longevity. Combined with modern eSIM management frameworks and lightweight communication protocols, it enables millions of constrained devices to stay connected for over a decade. This convergence of technologies lays the foundation for the next wave of large-scale IoT deployments where connectivity is seamless, energy-efficient, and crucially, built to last.