Internet-of-Things (IoT) sensor systems are increasingly being deployed in public transit, in-building, campuses, industrial complexes, and virtually all other environments where occupancy, security, and other critical data can be acquired by electronic sensors. Where there are potential efficiency, safety, or operational benefits from increased monitoring or sensor data gathering, there are now likely IoT sensor platforms available that can perform that task. These sensor modules are sometimes conductively connected, but it is increasingly common to find wireless IoT sensor platforms/modules that make use of the myriad of wireless communication technologies to relay vital sensor data. These IoT sensor systems often require gateways/hubs that are connected wirelessly or wired to the internet, or these sensors may include wireless communication modules to cellular, WiFi or other wireless services. Naturally, these services require extensive RF infrastructure, such as Cellular/WiFi/GPS combination IoT Antennas.
This post aims to provide a primer on IoT sensor wireless connectivity considerations, technologies, and cloud communication vectors. Readers should gain a foundational understanding of what types of wireless communication technologies exist and the common ways they are deployed.
IoT Sensor Devices Wireless Connectivity Considerations
There are a diverse range of IoT sensor types, and this influences the amount and type of data these sensors output, and how that data may be handled by wireless connectivity solutions. For instance, IoT sensor camera modules often output a substantially larger amount of potentially higher resolution data than a simple IoT temperature or barometric pressure sensor. Also, depending on the camera module and IoT application, the module may be outputting data continuously, as opposed to temperature or pressure sensors that may only need to transmit data every several seconds to minutes. The amount and frequency of data a sensor outputs has major constraints on what type of wireless connectivity module is suitable for that application. Wireless protocols, such as WiFi and 4G LTE/5G can often handle high data rates from camera modules where others, such as LoRA and Bluetooth are more suited to burst transmissions or low to medium data rates data streaming.
The type of IoT platform also has several factors on the available power, energy, and real estate for an IoT wireless connectivity module. Cellular modems for IoT platforms tend to be larger and more power consuming than small Bluetooth and Zigbee modules but may also offer longer range and higher data transmission rates. Cellular connectivity options, along with other proprietary connectivity options, often also require subscription services. The spectrum that a wireless connectivity solution operates in, as well as other key aspects of the transmission/reception and electrical operation are also often regulated in most countries and need certain licensing or certification to be used. The following is a snapshot of several of the most common IoT wireless connectivity considerations:
Common IoT Sensor Device Wireless Connectivity Considerations
- Data rate
- Data resolution
- Transmission distance
- Battery capacity
- Cost (wireless module, board space, wireless connectivity service)
- Licensed vs. unlicensed spectrum
- Carrier deployed vs. customer deployed
- Device density
- Deployment environment
- Firmware updates
- Component/module selection
- Antennas
- PCB real estate and fabrication considerations
The wireless protocol/standard that an IoT wireless connectivity module is built for has substantial implications on the capability and operation of the wireless connectivity option. There are a growing number of wireless protocols/standards to choose from, which often creates a challenge for IoT platform developers. Some wireless protocols/standards more common to certain applications, such as Zigbee/Thread/Matter being more common for smart home applications, where Bluetooth, WiFi, and Cellular technologies are more common to portable electronics and entertainment technologies. Example wireless connectivity hardware for cellular and WiFi industrial IoT systems includes components such as this Cellular/WiFi and GPS combination antenna.
The proprietary wireless connectivity options for IoT are often much more application specific, and may depend on centralized services, limiting the scope of their utility. However, open protocols/standards usually have vast ecosystems of hardware options and generations/variations that make compatibility and hardware selection extremely complex.
Common Wireless Protocols & Standards
- Advanced Message Queuing Protocol (AMQP)
- Bluetooth and Bluetooth Low Energy (BLE)
- Cellular, Long-term evolution (LTE) 2G, 3G, 4G, 5G, and future 6G
- COnstrained Application Protocol (CoAP)
- Data Distribution Service (DDS)
- Long range (LoRa) and LoRa wide area network (LoRaWAN)
- Lightweight machine-to-machine (LWM2M)
- Message Queueing Telemetry Transport (MQTT)
- Wi-Fi
- Extensible Messaging and Presence Protocol (XMPP)
- Zigbee
- Z-wave
- Thread
- Matter
- Ethernet Internet Protocol (IP)
- HyperText Transfer Protocol (HTTP)
- WebSocket
- Near-field communication (NFC)
- Sigfox
- Radio-frequency identification (RFID)
- OPC-UA
IoT Sensor Device Data Vectors to Cloud Services
A given wireless protocol/standard will have distinct modes of operation and how that wireless connectivity protocol connects to a network. Some IoT wireless devices connect directly to other wireless devices that they transmit data to, while others connect to larger networks of devices.
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Cloud Gateways/IoT Gateways
A method of extending internet/cloud/wider network networking capability to IoT devices that may not have substantial range is to use cloud/IoT gateways. These gateways use a wireless protocol/standard to connect to IoT devices, often many different types of IoT devices, and use another conductive or wireless connectivity technology to connect to a local area network (LAN), wireless area network (WAN), or internet modem. Some IoT gateways even have built-in internet or cellular modems to provide direct internet connectivity.
Smartphone/Cell Phone or Cellular Modem to Cloud
Many IoT sensor devices available to consumers or that benefit from provisioning and use with smartphones can pair with smartphones to connect to larger WANS or cloud services. Smart watches, smart rings, and personal medical devices are examples of technologies that make use of a smartphone as a vector for cloud service or wider network access. These devices often do not work if not paired to a cell phone/smartphone which creates a compatibility consideration and smart phone support challenge for companies that use this approach.
Direct IoT Sensor Device Wireless Connectivity to Internet Services
Some IoT sensors may include conductive Ethernet connectivity, or now, more likely WiFI or cellular modems that allow direct connection to cloud services or wider networks. WiFi and Cellular technologies are the most prominent versions of direct cloud/wider network connection for IoT devices, though there are also proprietary versions of these technologies available that offer certain advantages in some applications. It is often possible to purchase modules that offer Cellular or WiFI connectivity that can be either built into an IoT PCB or connected via common interface buses, such as I2C, SPI, Ethernet, or USB.
References
- A Study of Efficient Power Consumption Wireless Communication Techniques/ Modules for Internet of Things (IoT) Applications