The Internet of Things (IoT) is fast becoming a household word, but just what is it and what does it have to do with wireless communication? Let’s break it down.
What is the Internet of Things?
Generally speaking, IoT refers to everyday objects having network connectivity for sending and receiving data. It’s big business across a wide spectrum of applications, and the worldwide transformational implications has some industry experts forecasting the global IoT market to be worth around $14 trillion by 2020.
Particularly hot categories under the broad IoT umbrella include:
- Wearable electronics that combine lifestyle, medical, wellness and safety/security needs with improved monitoring and communication
- Intelligent traffic management that allows for enhanced state and federal intermodal communications and advanced vehicular safety and autonomy
- Smart meters that align consumer habits with actual costs as they relate to household management and energy use (electrical, solar and wind)
- Process control for industrial production that provides local/remote monitoring and control of manufacturing to increase efficiencies
There is one IoT commonality among these disparate applications: wireless communication, more commonly known as wireless.
What is wireless?
Wireless is a method of transferring information through electromagnetic radiation (radio waves) between points that are not physically connected.
Energy for wireless is produced by oscillating electric and magnetic disturbances characterized by amplitude, wavelength and frequency that generally exist between 1kHz and 1THz. The range between 3kHz and 300GHz is regulated by government agencies worldwide, meaning company and technology use is strictly allocated.
To avoid these governmental restrictions and also combat underperforming wireless reliability, as in Bluetooth pairing and connectivity in the automotive industry, most IoT applications operate in the frequency “sweet spot” of 300MHz to 5GHz. This frequency is low enough to have sufficient range and high enough to avoid natural interference without needing a line of sight, making it ideal for small antennas and higher transmission rates.
Industrial, Scientific and Medical (ISM) Radio Bands
In particular, 2.4GHz is popular for IoT use because no licenses are required to operate in this frequency in order to foster industrial, scientific and medical (ISM) uses like microwave ovens, plasma lamps and plastic welding torches.
To take best advantage of the 2.4GHz range, ISM bands include 13.56MHz, 915 MHz, 2.45GHz and 5.8GHz; however, the range does not preclude a great deal of interference from other devices and equipment resulting from no regulatory protection or organizations’ deliberate nonconformance to regulation requirements.
Wireless Personal Area Networks (WPANs)
ISM bands have gained popularity for low-power, short-range (<30km) wireless personal area networks (WPANs), as they are unlikely to interfere with or receive interference from high-power ISM applications that are forced into specific locations, like hospitals or manufacturing facilities.
WPANs are defined by their frequency and protocols, and include:
- High-throughput/high-power wireless
- Typically plugged in, not power-constrained or battery-sensitive
- Each new generation attempts to increase throughput
- Uses Direct-Sequence Spread Spectrum (DSSS) and orthogonal frequency-division multiplexing (OFDM) for interference avoidance
- 13 channels, each 22MHz wide (three can operate without interference)
- Frequency agile, meaning listening occurs before transmission and switches when the quality of the original channel degrades
- Supports a single to many or single-to-single network, but does not support a mesh network which affects reliability
- Moderate throughput for devices assumed to be recharged regularly
- Several generations have been created, with Version 4.0 allowing for operation at low power with limited range
- Uses Frequency Hopping Spread Spectrum (FHSS) for interference avoidance
- Supports start network (one master to seven slaves) and single-to-single, with mesh network compatibility implemented in 2016
- High-throughput/low-power for devices expected to be plugged in intermittently
- Similar to Bluetooth in range, but uses DSSS for interference avoidance
- A less popular WPAN option
Zigbee/Wireless HART/ISA 100
- Low throughput/low power for devices with anticipated lifetimes of up to 10 years using just two AA batteries
- Use <1GHz and >1GHz frequencies in ISM band
- Use DSSS to avoid interference, and select/switch channels based on the one with the fewest networks and the appropriateness of the channel
- Supports star and mesh networks
- Zigbee is used primarily for home networks; Wireless HART and ISA 100 are directed to industrial environments because they are more reliable
Radio Frequency Identification (RFID) and Near-Field Communication (NFC)
- RFID is one-way communication; NFC is a subset of RFID
- Both types can be passive or active, meaning it can be powered by the reader (passive) or have an external power source that boosts range potential but lowers battery life (active)
With current technologies, these protocols aren’t mutually exclusive. Products are designed to use more than one of these protocols, such as having Bluetooth and WiFi on the same device, and proprietary protocols are also being combined with standard protocols.
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