IoT Protocol Selection and Design Guide

Created: July 8, 2021
Updated: October 10, 2024

Think about your options for wireless communication these days, and three primary protocols come to mind: WiFi, Bluetooth, and cellular. Each of these has been massively successful and shouldn’t be overlooked for consumer electronics designers. If you’re putting out anything billed as “smart” or “connected” for the consumer segment, including WiFi and Bluetooth (or both) is almost mandatory at this point. However, there’s a lot that goes on behind the wireless protocol, with IoT application layer protocols being implemented on devices to support different messaging modes or full-on communication over the internet.

The IoT world can be an alphabet soup of wireless protocols and application layer protocols, so it can be difficult to see where to get started outside of just using WiFi and Bluetooth to provide connectivity between devices. I’ve seen more designers jump into the world of IoT development recently and even releasing some open-source projects that integrate several capabilities into a single package. However, most of these just go the easy route of using WiFi + Bluetooth/BLE to provide some flexible connectivity options. There are actually many more IoT wireless protocols and data layers that will work very well for your system without all the overhead of WiFi and Bluetooth.

Let’s look at some of the hardware options, wireless protocols, and application layer protocol options you can use to innovate new IoT systems. Choosing the best option for your new product requires pairing hardware to support your desired wireless protocol and an application protocol to support messaging. With the right combination, you can build a product that’s more reliable and faster than the typical WiFi + Bluetooth system using lightweight protocols.

Designing With IoT Protocols in 2021

Today, there are plenty of options for building your product with wireless protocols, and there are over a dozen wireless options you can implement to build out your platform. With the obvious growth in connected consumer and office products over the past decade, there is always demand for the massively successful WiFi + Bluetooth combination that can connect to the internet connection. However, other combinations of wireless protocols and application layers quickly reveal their worth in particular applications.

Then, there is the chipset to consider. In-demand products that might need WiFi + Bluetooth or Zigbee are highly integrated. Many mobile chipset makers will offer SoCs that integrate MCU functionality onto the same die as a transceiver and even a power amplifier for transmission. To get started, you need to think about basic requirements for your device like data throughput and power consumption, both of which relate to the protocol you select.

Selecting a Wireless Protocol

Before you start shopping for hardware, you’ll need to match the needs of your system to an IoT protocol. Here are the major areas to look at when selecting an IoT protocol for your system.

Operating frequency and coexistence. If wireless is involved, you’ll need to consider which frequency you’ll operate in, which might depend on the environment. Most IoT protocols operate in unlicensed bands, which brings challenges in coexistence as the band is effectively unregulated (aside from EMC requirements). Some chipsets are specifically designed to support coexistence under an IEEE 802 series standard.
Power consumption and range. Will the endpoint on the network operate on battery power, or will the design operate at higher frequencies that require more power? How much power is needed to hit your target range? Some protocols perform better in this area than others. If your device is battery operated, you’re going to want to select a low-power protocol.
Data throughput. Are you building a system that needs to stream media, or are you sending small packets of data? Is communication intermittent or do you need continuous transmission/reception of data? Sub-1 GHz protocols will give you lower data rate in the kbps range, but this is still sufficient for many lightweight data acquisition tasks,
Network topology. The two standard IoT network topologies are star and mesh. Star networks may require some centralized gateway to mediate messaging between endpoint devices, depending on the wireless protocol standard and application layer protocol. Some mesh networks (e.g., Zigbee) will also require a gateway device.

Like most design and engineering choices, selecting an IoT protocol involves a series of tradeoffs. For example, working at higher frequency requires more power for transmission to provide the required range, but it also provides higher data rate. Then depending on the topology you need, you might not be able to hit your data rate requirements. The table below provides a summary of the common IoT protocols and their capabilities in your design.

*Credit for table data goes to GlowLabs.co

There is one other area that hasn’t been mentioned yet: security, particularly in areas like defense, critical infrastructure like utilities, industrial systems, and even automotive. This is a complex area of IoT design and development as it is constantly evolving at the software level and in terms of network management. Since it’s extensive enough to deserve its own series of articles, we’ll save that topic for later. Given all the possible wireless protocols you can implement on your hardware platform, coexistence is a challenge in some systems, particularly in the 2.4 GHz band.

Coexistence Challenges

Problems with coexistence, and the need for a chipset that can accommodate it, could be the deciding factor when building an IoT platform that will operate in an ISM band. 2.4 GHz is the only frequency that is unlicensed globally, so you shouldn’t be surprised when coexistence problems keep coming up in popular IoT protocols. However, with everyone having a high-frequency, high throughput network in their homes and offices, the industry now produces some chipsets that help overcome these problems for specific combinations of protocols.

The consumer and commercial space relies heavily on WiFi + Bluetooth, and possibly Zigbee, but there are several products you can use that support coexistence. Beyond these integrated solutions, coexistence can be implemented at the hardware level as follows:

Time-division multiple access (TDMA): This is the simplest coexistence method; one protocol is broadcasting while the other is deactivated.
Frequency-division multiple access (FDMA): The host driver is used to avoid using the same frequencies for two protocols in the transmit and receive directions. This takes up more spectrum but allows simultaneous transmits and receives.
Frequency-hopping spread spectrum (FHSS): Radio signals are transmitted over multiple channels within a band by rapidly changing the carrier frequency between transmissions.

If a standard, highly-integrated solution is unavailable, you may need to compile components into a custom chipset, e.g., an FPGA or MCU with a custom RF front end or similar solution. Outside the consumer space, coexistence challenges only get more interesting, especially because there may not be a highly integrated chipset that has coexistence solutions built in. Today’s enterprise/industrial IoT products are using more than WiFi and Bluetooth; IoT gateways, for example, can have four or more of the common ISM-band IoT protocols and possibly a sub-1 GHz protocol operating simultaneously. In some specialty areas like meteorology, aviation, and defense, you also have applications like radar operating in the 5-6 GHz band, creating a new coexistence problem with WiFi 5, 6/6E, and newer protocols.

Application Layer Protocol

In contrast to a wireless protocol, an application layer protocol (sometimes called a data protocol) describes the format in which data is transferred around the network, as well as the connectivity method between hosts and endpoints. This is defined in the firmware (for MCU-based architectures) or embedded software as part of your application. If you look online, you’ll find several libraries and tutorials for building an application running on TCP/IP or UDP with different application layer protocols. Some examples are shown below.

Multi-band IoT Protocol Components and

No matter how you want to build your IoT platform, the processor and RF front end you choose will form the foundation for your system and your application. Today, there is a range of WiFi + Bluetooth capable SoCs that can also support additional protocols in the 2.4 GHz ISM band. Other components can support sub-1 GHz alongside specialty 2.4 GHz protocols.

Nordic Semiconductor, nRF52820

The nRF platform from Nordic Semiconductor is very popular in lightweight embedded systems and compact IoT platforms. The nRF52820 microcontroller supports mesh networking over 802.15.4 + Zigbee, Bluetooth 5.2/BLE, and Thread. It also includes several interfaces you’d expect to find in an IoT microcontroller (SPI, UART, USB, and GPIOs). This component has small footprint while supporting multiple 2.4 GHz bands. Nordic also provides an extensive SDK and libraries you can use to develop your application.

NRF52820 application schematic. Source: NRF52820 datasheet.

Microchip, AT86RF212B-ZUR

The AT86RF212B-ZUR from Microchip is a multi-band transceiver that supports ZigBee at 700/800/900 MHz, IEEE 802.15.4, 6LoWPAN, and ISM communication. This transceiver interfaces with an MCU over SPI, as shown in the signaling diagram below. This component or a similar component is a great option for supporting a lightweight MCU that might not have an integrated RF front end.

Signaling diagram and application schematic. Source: AT86RF212B-ZUR datasheet.

Other Components for Building IoT Platforms

Even though software and firmware developer drive so much of an IoT platform’s functionality and capabilities, it all rests on hardware at the end of the day, and it’s important to select the right components to support your system. The components you include in your IoT platform need to interface with other systems over wired or wireless protocols, as well as ensure long lifetime and reliability.

Once you select your IoT protocol and determine how to solve any coexistence problems, you can find the components you need to build your application with the advanced search and filtration features in Octopart. When you use Octopart’s electronics search engine, you’ll have access to up-to-date distributor pricing data, parts inventory, and parts specifications, and it’s all freely accessible in a user-friendly interface. Take a look at our integrated circuits page to find the components you need.

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