If you’re reading this, it means you’re designing a device that needs wireless for connectivity, location, timing, or all of the above. It also means you’re looking for advice about how to pinpoint the wireless technology or technologies that meet your customers’ unique requirements for performance, reliability, security, coverage, and cost.
Navigating the options is challenging even for experienced device OEMs and systems integrators because there are so many to choose from and more on the way, such as 6G cellular and additional GNSS signals. The device’s target market can exacerbate this challenge if it will be sold in or travel to multiple continents because network support and regulatory requirements can vary significantly.
For example:
- As their acronym implies, LPWAN technologies offer low-power and wide-area capabilities.
- 5G RedCap aims to make cellular more affordable for cost-sensitive IoT applications.
- Wi-Fi connectivity is widely available in offices and public places such as malls and airports.
- For short-range connectivity, Bluetooth, Zigbee, and Thread are viable options for smart home and office applications, especially those that benefit from mesh networks.
- RFID, NFC, and UWB are popular choices for short-range applications that also need positioning and secure access capabilities.
All of these technologies have one thing in common: Each is supported by standards bodies and industry associations, such as 3GPP in the case of 5G and 6G, the CSA for Zigbee, and the LoRa Alliance for certain types of LPWANs. By following these organizations, engineers at device OEMs and systems integrators can gain valuable insights into how a particularly technology is evolving in terms of capabilities, regulatory oversight, and market adoption.
Another important tip is to keep the number of wireless technologies to a minimum. Take the example of devices with embedded antennas, which rely on the PCB to serve as their ground plane. The choice of RF technology — such as cellular, GNSS, Bluetooth, Wi-Fi and so on — determines the bands that the antennas must support and thus the ground plane size requirements. The more technologies that a device supports, the more difficult it becomes to create a PCB big enough to provide an adequate ground plane and still fit the form factor — especially if the device is small, such as a wearable or asset tracker.
Cellular
Cellular connectivity offers the most comprehensive geographic coverage of all wireless technologies. It also uses licensed spectrum, which helps ensure reliable service. These benefits come at the price of a data plan, which can be an issue for devices and applications aimed at cost-sensitive users.
The ongoing roll-out of 5G networks is set to deliver step-changes in data rates and latencies. Future 3GPP releases will continue to improve cellular IoT and push this connectivity option to serve more IoT applications under one network.
LPWAN
LPWAN is a catchall term for any network that supports communication over long distances and uses minimal power. These networks are best suited for applications that send small and infrequent amounts of non-time-sensitive data, such as smart metering, asset tracking, smart agriculture, and environmental monitoring.
Some LPWANs use licensed spectrum, while others use unlicensed bands. LoRaWAN and Sigfox are leaders in unlicensed LPWAN networks. Developed and maintained by the LoRa Alliance, LoRaWAN is based on an open standard with an architecture based on gateways that relay messages between devices and a central network server. LoRaWAN can be deployed as a private network or offered as a public network through integrators. The Sigfox network is owned and maintained by a French company, is based on patented, proprietary technology, and is operated on a subscription model.
Licensed LPWANs use cellular networks and typically offer higher-quality connectivity, with less interference and fewer dropped connections. The three primary cellular standards aimed at IoT applications are NB-IoT (LTE Cat-NB), LTE-M (LTE Cat-M), and LTE Cat 1bis. Each has its advantages in terms of cost, data rates, and power consumption, and coverage of NB-IoT and LTE-M is more fragmented than LTE Cat 1bis. (For more guidance, see “Choosing the Right LTE Standard for IoT Applications” and “LTE Cat 1 bis Explained: The Future of IoT Connectivity.”)
Short-Range Wireless
Short-range wireless arguably is the most complex and fragmented type. This is due to the wide range of technologies, each adapted to different sets of requirements. In many cases, these technologies offer overlapping capabilities. Major short-range technologies include:
- Bluetooth is widely used for short-range communication between devices such as headphones, speakers, and smartwatches. Bluetooth Low Energy (BLE) is a power-efficient version designed for battery-operated devices and low-bandwidth applications.
- NFC and RFID are used for applications such as contactless payments, asset tracking, and access control. Both operate in the unlicensed 13.56 MHz band, with NFC being a subset of RFID.
- Thread is a low-power, mesh networking protocol designed for IoT applications, particularly smart home devices. Thread enables devices to communicate with each other and the internet using IPv6, offering a more robust and efficient alternative to Wi-Fi or Bluetooth for certain applications.
- Ultra-wideband (UWB) technology is a short-range, high-bandwidth wireless communication technology that uses radio waves to achieve precise location and tracking capabilities. It operates over a wide frequency band with low power, minimizing interference with other wireless systems, UWB delivers high-accuracy distance measurement, with centimeter-level precision. UWB is also highly secure and is well-suited to applications such as precise location and tracking, indoor navigation, secure access control, and wireless payments. (It’s important to note that this type of UWB is not the same as 5G cellular, which sometimes is referred to as ultrawideband.)
- Wi-Fi has long been the dominant technology for local wireless networking in homes, offices, and public spaces. It operates in unlicensed spectrum (2.4 GHz, 5 GHz, and 6 GHz), providing high-speed data transmission but with a limited range compared to cellular networks.
- Zigbee primarily targets IoT applications in smart homes, industrial automation, and energy management. It operates in the 2.4 GHz ISM band and is designed for low-power, low-data-rate applications.
Selection Tips
Licensed spectrum technologies like 5G, LTE, and NB-IoT offer guaranteed coverage, interference resistance, and higher data rates, but come with higher costs and regulatory oversight. Sigfox, Wi-Fi, Bluetooth, and Zigbee have lower costs but can suffer from interference and congestion in crowded environments such as factory floors.
The wireless technology roadmap will significantly influence the longevity of your device. LTE-M and NB-IoT will continue to operate on 4G networks for the foreseeable future, and RedCap chipsets are only just arriving on the market. As a result, device OEMs and systems integrators must choose mature networks or be certain that the emerging RedCap ecosystem will align with their product roadmaps. (For a deeper dive, see “4G vs. LTE vs. 5G: How Mobile Technology is Evolving” and “With 5G RedCap, Less is More for IoT.”)
Also, with each new release, capabilities can overlap. Bluetooth 6.0, for example, is endowed with new features improving its competitiveness in the positioning market, and Zigbee, Thread, and Bluetooth mesh all offer capabilities to the developer of smart home applications.
Finally, consider how much bandwidth your customers will need now and whether that will increase over the life of your device. This also helps avoid PCB ground plane and BOM cost overruns is by determining whether a single technology can do the job of multiple ones.
For example, an Industrial IoT (IIoT) device might not need Wi-Fi if it’s designed for applications where 4G or 5G is available. Many factories are already migrating away from Wi-Fi and/or Ethernet in favor of private 4G/5G networks for reasons such as greater data security and the ability to support mobile applications such autonomous guided vehicles (AGVs). For those customers, new Wi-Fi technologies such as HaLow or Wi-Fi 7 may be superfluous.
GNSS
Sometimes the device’s use case requires multiple technologies. For example, asset trackers use GNSS to support timing and/or positioning, and cellular to report that information. For engineers, one important consideration is making the cellular and GNSS systems coexist on the same PCB. The smaller the device, the more challenging this is.
Take the example of an asset tracker whose LTE radio is desensitizing the GNSS Low-Noise Amplifier (LNA), thus undermining accuracy. One solution is to use a GNSS antenna with an integrated notch filter to block those cellular signals at the specific frequencies where they originate, such as LTE Band 13.
Sometimes the device’s use case requires multiple versions of the same technology, such as asset trackers that will be affixed to shipping containers or high-value construction equipment. Depending on where those will be used, the tracker might need a GNSS receiver and antenna system capable of supporting multiple signals from the same constellation or multiple constellations. (For a rundown of all the current and forthcoming options, see “How to Navigate the L1, L2, L5, E5a, E5b, and G2 Alphabet Soup of GNSS Constellations and Signals.”)
Suppose the tracker’s host device will travel through latitudes above 55 degrees, and the use case requires high accuracy at all times. GPS alone might be insufficient because its satellites rise only 45 degrees above the horizon, thus limiting the tracker’s visibility of that constellation. Adding support for GLONASS and/or Galileo fills this gap by enabling the tracker to take advantage of constellations whose orbits provide better coverage in higher latitudes. (For more information about how latitude affects GPS accuracy, see “GNSS/INS Simulations of High-Latitude Operations.”)
