Wireless technologies for the Internet of Things: Enabling radio frequencies

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Wireless technologies for the Internet of Things: Enabling radio frequencies [Copy link]

In its simplest form, IoT wireless technology requires a radio that can receive and broadcast radio waves as a means of transmitting signals or data. The slides below and above share an overview of radio frequencies and how they support IoT wireless technology solutions.

What are radio waves?

Radio waves are electromagnetic frequencies used for long-distance communication. IoT solutions rely on IoT wireless technology, which utilizes radio waves following specific protocols as designed by the IoT system. IoT devices use radio protocols to transmit data to the cloud platform without the presence of a physical or wired connection. There are many different protocols to choose from, with different characteristics in terms of power consumption, physical size, transmission distance, data size, and availability of transmission technology.

Radio wave basics

There's a good chance you haven't thought about radio waves since your last Science Fair project, so let's review the basics before we dive in.

Radio waves are electromagnetic waves that travel at the speed of light. The wavelength of an electromagnetic signal is inversely proportional to its frequency.

Amplitude represents the strength of the RF signal. This is determined by whether there is a 1 or a 0 in the digital signal. This type of modulation is not ideal due to the amount of noise in the transmission medium. Frequency Shift Keying (“FSK”) slightly changes the frequency of the carrier signal to represent data in a way suitable for traveling over the air at low to moderate data rates. FSK also avoids the effects of common noise.

Another type of modulation is phase shift keying ("PSK"). PSK causes the phase of the signal to vary while the frequency remains constant. Like FSK, PSK is largely immune to common noise based on amplitude variations.

Frequency is the number of times a signal repeats per second and is measured in Hertz ("Hz"). Phase indicates how far the signal deviates from a reference point.

Radio Technology

A radio band is simply any frequency of electromagnetic waves used in radio communications. They range from 3khz to 300Ghz, covering everything from amateur radio bands to cell phones. There are also multiple types of bands:

Unlicensed bands have become a popular approach for many commercial solutions (Bluetooth, WiFi, etc.)

Licensed frequency bands require permission from local regulators and are primarily used by television and cellular networks

Forbidden Bands are used by government agencies and public service organizations

Radio frequencies are versatile, but like any job, you need to choose the right tool for your IoT wireless technology needs. Does your device transmit large amounts of data frequently? You need a high-bandwidth solution. Does your device need to transmit data over long distances? A lower frequency will do the job. There are many factors to consider when choosing a radio solution, but there are also many options to suit any need.

Long Range IoT Radio Solutions

Cellular Network

For long-range connectivity, many IoT wireless technology solutions will leverage cellular networks, as they typically have readily available development hardware and well-defined protocols. Cellular technologies such as 3G and 4G (and the upcoming 5G) are widely used in IoT systems. 2G was also used, but has been largely decommissioned since AT&T shut down 2G service in 2016.

However, cellular networks are not without their drawbacks. First, they are expensive. They are also designed for voice and low-latency communications, which are not typical requirements for most IoT wireless technology solutions. Finally, the cellular device certification process is time-consuming and expensive, which can be prohibitive for some smaller IoT solutions.

Low Power Wide Area (LPWA) Networks

New LPWA networks are entering the IoT space to meet some of the unique needs of IoT devices. For example, LPWA networks extend coverage into difficult radio environments. They also support very low power operation, extending battery life. Two of the emerging solutions are licensed spectrum LPWA and unlicensed spectrum LPWA.

Long Range (LoRa)

LoRa (short for Long Range) continues to gain traction in the market. It offers a compelling combination of long range, low power consumption, deep indoor coverage, and secure data transmission. LoRa operates in the unlicensed <1GHz frequency range. It uses spread spectrum technology, making it less likely that adjacent transmitters will interfere with each other. This increases the capacity of each gateway. Spread spectrum communications also provide "coding gain" over narrowband communications. This results in a stronger communication link that can support communications over longer distances. LoRa data rates range from 0.3 kbps to 50 kbps, and can support ranges of up to 15 km.

While the range of a LoRa system is attractive, there are some tradeoffs. To achieve the longest distances, you must use very low data rates. For example, a range of 15 km uses a data rate of about 100-300 bps, and the range drops rapidly as the data rate increases. The lower the data rate, the longer it takes to transmit the data, which in turn drains the battery. A reliable LoRa design balances the amount of data and transmission speed with power consumption and range requirements. This IoT wireless technology system is best suited for applications that only send bytes of data a few times a day. It is not ideal for wireless systems that send large amounts of data, need to guarantee quality of service (QoS), or require low latency or tight synchronization.