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Blues University is an ongoing series of articles geared towards beginner- and intermediate-level developers who are looking to expand their knowledge of embedded development and the IoT.
Introduction: Why IoT Network Connectivity Matters
Internet of Things (IoT) devices are edging into almost every sector, from industry to healthcare to homes. At the heart of every IoT solution is a network to retrieve data, potentially analyze it, and take action.
The connection's physical properties are vital to the device's success. If a device uses a connectivity option that only works within a short range, it can restrict movements. Likewise, a connectivity option that consumes a great deal of energy can impact the device's form factor and/or deployment options.
In this article, we'll explore the available IoT network connectivity options and help you determine which to choose for your device.
Wi-Fi, Bluetooth, Zigbee, and LoRa: Short Range Offerings
IoT connectivity options are vast, from widely known standards like Wi-Fi and Bluetooth to niche options and proprietary protocols like Zigbee.
Wi-Fi
While Wi-Fi is a standard for high-data-rate applications, it consumes plenty of energy. Its 100-meter range surpasses standard Bluetooth, and its chips are relatively cheap. However, you must secure the Wi-Fi connection with WPA2, WPA3, or other encryption protocols to prevent unauthorized access.
Bluetooth
In contrast, Bluetooth is suitable for low-bandwidth, short-range communications. Its protocol handles security through pairing, with a relatively low cost per chip. Additionally, its long battery life is a significant advantage.
Bluetooth Low Energy
Similar, yet with some critical differences, is Bluetooth Low Energy (BLE). This modern standard extends battery life (using 35mA in idle mode) and offers a range of up to almost a kilometer in optimal conditions, although usually not as far in practice. Sometimes, its range is less than a meter.
"Smart Home" IoT Connectivity Options
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You may be familiar with another communications option, Zigbee, often used in smart home lighting and popular in thermostats, window and door sensors, and other solutions. Zigbee boasts low power use, as little as 1 µA in sleep mode, where many Zigbee devices spend most of their time. It works in a close-proximity (90-meter) mesh network, ideal for smart home applications as it saves energy, and you can extend its coverage by using devices as repeaters. Its cost per chip is about double that of Wi-Fi or Bluetooth.
New standards are emerging in IoT, too, most notably Matter and Thread. Matter supports more energy-intensive applications, while Thread is a compatible standard for low-power devices. Their main advantage over Zigbee is that they don't need a gateway or translator to communicate, setting them up to overtake Zigbee as the IoT communications standard.
While all of these connectivity options might be suitable choices for short to medium-range communications, they fail to qualify over ranges of several meters. LoRa, named for long range, communicates over a line of sight up to 10,000 meters or more. Like the others, this low-power wireless platform runs in license-free frequencies, and its cost per chip is similar to Zigbee. Yet, LoRa depends on gateways for device-to-device communication, introducing another layer of complexity.
Exploring Cellular IoT for Long Range
General-purpose cellular networks have great coverage, as almost everyone already uses them for mobile phones, smartwatches, and other devices. These networks typically operate in the commercial 800 MHz to 5 GHz radio frequency band, the wideband (WB).
While standard consumer devices usually use SIM cards bound to specific networks, cellular IoT uses machine-to-machine (M2M) SIM cards. Modern M2M SIM cards support a variety of frequencies that work for roaming and are well-suited for outdoor applications.
These M2M SIM cards are usually centrally managed on a platform, so the device vendor can configure and adjust its setup. The card's lifetime is typically up to 10 years, longer than a standard SIM card. M2M SIM cards vary in purchase cost, form factor, usage cost, global coverage, and security capabilities such as private network communication.
Defining NB-IoT and its Significance in IoT
In contrast, narrowband IoT (NB-IoT) focuses on low data rates. Its specification lists download peak data rates of 26 kbit/s compared to long-term evolution (LTE) and other WB connections at 10 Mbit/s. NB connections also have a much higher latency than WB, at potentially 1.5 to 10 seconds in optimal conditions instead of LTE's 50 to 100 ms.
NB-IoT is best for non-real-time applications requiring low cost and power consumption. Potential use cases include tracking devices and smart electricity, gas, or water metering. NB uses part of the LTE standard, so it's available everywhere 4G is available. Although they sit atop the same infrastructure, NB IoT chips are much cheaper than LTE chips.
Cellular Generations: 2G to 5G
Let's dive a bit deeper into cellular network specifics. The generations have different specifications associated with their release number. The first generation, 1G, in the 1980s, was followed by its successor, short 2G (GSM), in 1990. 3G (UMTS) and 4G followed, with 4G's extension, long-term evolution (LTE), enabling high-speed data transfer. Suddenly, streaming a movie on a cellular phone became a reality!
IoT connectivity solutions that offer access to LTE Cat-1 and LTE Cat-1 bis provide a fantastic balance in latency, bandwidth, and power consumption for battery-powered devices.
Today, the industry is up to 5G. This generation promises low latency with even higher bandwidth since its designers modeled it to fulfill the data needs of sensor-equipped automobiles. The 5G specification is generally considered the future of IoT for mobility applications.
The 2G/3G "Shutdown" and Implications for IoT
As cellular providers adopt new specifications, they also need to streamline their physical network infrastructure. Consequently, older technologies such as 2G and 3G have been gradually fading into a so-called "shutdown." As GSM and UMTS (2G and 3G) are now more than 20 to 30 years old, the providers' maintenance costs have become unbearably high.
The shutdown is provider-specific. In some countries, providers shut down 3G even before 2G. The reason is simple: While 2G is still relevant for emergency calls in rural regions, 4G and 5G have superseded 3G's coverage and usability.
The impact on IoT deployments might be drastic if you have an older device with a chip supporting 2G or 3G. Since a new generation appears roughly every ten years, consider this lifespan when selecting your device's connectivity option. For instance, you may want to avoid releasing a device now that only supports 3G. Even 4G might only offer about ten years of ensured connectivity.
Choosing the current generation when selecting cellular technology is a good idea. 5G is expected to persist until the 2040s.
The modular design of the Blues Notecard makes it a future-proof option for designing cellular, LoRa, Wi-Fi, or satellite connectivity into your IoT product.
So, what do you do if you have an older device? Some applications might be able to use minor software upgrades to make the transition. However, you must budget for hardware upgrades.
Your first step is to take inventory of your current devices and networks. Then, develop your transition strategy to newer technology. Finally, plan and budget for future upgrades.
The Rise and Fall of Connectivity Protocols
In the last decade of IoT devices, connectivity protocols have consistently evolved. New standards formed, while old ones disappeared, some quite quickly. It's often quite challenging to predict how a certain standard will evolve.
Sometimes, IoT technologies flourish because they have a broader range or are faster, cheaper, longer-lasting, compatible, secure, or easier to work with. Sometimes, they flourish because a leading technology provider adopts them and dominates the market.
For instance, Zigbee's rise to become a smart home system standard was unpredictable, even when counting on Philips' and other vendors' market presence. In comparison, Z-Wave, a similar standard introduced at roughly the same time, had higher interoperability but a slower data transmission rate. It didn't gain the same adoption.
Any new connectivity protocol must stay within its physical boundaries. There's just so much spectrum available, either below 1 GHz or around the 2.4 or 5 GHz radio frequency band. All others are licensed, forbidden, or simply not feasible.
New standards like Matter actively push interoperability forward while remaining as scalable and secure as possible.
Introduction to IoT Security Challenges
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While securing IoT devices poses many challenges, we'll focus on data privacy, resource constraints, and network access.
Encrypting communication channels and IoT devices is critical because these devices can expose user habits, and each device can be an entry point for new attacks. Yet, IoT devices often have low power, limited memory, and minimal CPU capacity due to cost or size constraints, so they might not have the resources to store encrypted data. Ensuring that the encryption isn't easy to break can also be challenging.
Since the IoT industry aims to maximize cost-per-unit and time-to-market, the makers must balance these considerations with ensuring adequate security.
IoT devices must be secure against man-in-the-middle attacks, where an attacker pretends to be the correct communication counterpart. However, reliable local encryption is the only way to verify the communication partner's identity. It's crucial to ensure that only trusted devices enter the network.
Security often relies on software solutions, which you must keep up to date. Over-the-air (OTA) update functions help maintain security. However, these updates may interrupt the device's primary function or need to wait until the device is ready. Often, IoT devices outlive their support, so security updates may not be available, making them vulnerable.
The devices must also connect to the network long enough to receive the update — and a partial update could brick the device or cause it to behave unexpectedly. Many manufacturers fail to future-proof their devices by considering how to update OTA. You can mitigate update challenges by testing connectivity before beginning the update and sending smaller updates.
This just one of many advantages to choosing a wireless connectivity solution like the Blues Notecard and its paired cloud service, Blues Notehub. The two work together to form a secure, "off the public Internet", device-to-cloud link with developer-friendly cellular, Wi-Fi, LoRa, and satellite connectivity options.
Selecting the Right Connectivity for Your IoT Solution
Range, bandwidth, power consumption, and scalability drive IoT device makers to specific solutions.
So, while the two options may look similar from a technical perspective, their non-technical properties aren't. For example, chips may have hidden costs, like cellular chips requiring contracts with network providers.
Other hidden challenges may include waning support for the connection type. Incompatibility with other devices is a concern, too, since a specialized unit may need more time and effort to integrate with a desired connectivity solution.
The need for ongoing maintenance is another hidden consideration. It's easier to maintain local device hardware than a sensor on a remote mountain or the top of the Golden Gate Bridge. It's also cheaper to update a device's software over a local network than a cellular connection.
First, understand your device and its use case. Does it need to conserve power or work over long distances? Does it need to continuously transmit a large quantity of data or occasional little bytes of information? Does your network choice have the capacity to scale as needed?
Also, consider the device's environment. For example, a wearable health tracker may not stray far from a Wi-Fi network or Bluetooth receiver, while a moisture sensor in a remote forest might only have access to a cellular network.
Future Trends in IoT Connectivity
With all the changes in IoT since its inception, you may wonder what's next. More advanced standards for Bluetooth, Wi-Fi, or other protocols might be more IoT-friendly, like Wi-Fi 6 and Bluetooth Low Energy.
Many IoT manufacturers are anticipating 6G. According to the Bharat 6G vision statement, 6G will "build upon 5G technology and provide more reliable, ultra-low latency and affordable solutions with speeds almost 100 times faster than 5G." So, while 5G already focuses on low latency and high data bandwidth, 6G could be a game changer due to its various supported use cases. It will enable the integration of artificial intelligence and machine learning services into devices for smart connectivity.
As a side effect of 6G technology, edge computing will become more viable. The future might not be centrally controlled IoT networks but distributed networks that use AI and smart contracts. Naturally, IoT deployments might look drastically different than today.
Conclusion
Choosing the right connectivity option is key to giving your device the desired functionality and usability. While some standards feature a more extended range, others are more secure, consume less power, or have inbuilt compatibility with other protocols.
Wi-Fi has a decent range and works great for high data rates, but it requires encryption. Bluetooth works over a shorter range, yet it uses pairing for security and offers a long battery life. Zigbee boasts low power consumption but is suitable for small areas like homes.
Specialized communication protocols like Matter and Thread work for energy-intensive and low-power devices, respectively, and outshine Zigbee with their ability to communicate without a gateway or translation.
LoRa offers a practical option for long-range use and consumes little power. Cellular communication provides an excellent long-range communication option, and this standard technology enjoys high compatibility with existing networks and devices.
Ultimately, your specific device and use case will determine your best IoT connectivity choice, and often, the solution may incorporate a combination of connection technologies. For example, Wi-Fi-dependent IoT devices demand reliability, necessitating a fallback solution should an outage occur.
Fortunately, the newest Blues Notecards rise to the occasion. The Notecards provide easy access to cellular, Wi-Fi, LoRa, and satellite data. The cellular options abound with wideband (LTE Cat-1), midband (LTE Cat-1 bis), and narrowband (LTE-M and NB-IoT). Multiple out-of-the-box connectivity options ensure robust service, wherever and however your devices need it.
If you're new to embedded development and the IoT, the best place to get started is with the Blues Starter Kit for Cell + WiFi and then join our community on Discourse. 💙
