Wireless Communication Options: Part 1

[Joel_Weder]

This is the first in a series of blog posts about wireless communication options for remote SCADA and Telemetry purposes. We hope you find these useful as you consider your organization's path forward. 

Introduction

There is a rapid growth of new wireless technologies, enabling smarter remote devices and new concepts in communication technology. As a result, the wireless industry is undergoing a transition in multiple areas, and this process seems to be accelerating. As with any evolutionary phase, opportunities arise which must be evaluated.

Anyone providing or purchasing solutions in this industry must stay flexible and open to new ideas. This may involve exploring technologies that are showing signs of becoming game-changers, and being willing to quickly take advantage of opportunities that arise. 

Higher data rates, lower cost, lower power budget, more cyber-security features, simpler setup, operation over longer distances and in difficult locations are all in high demand. IIoT (Industrial Internet of Things) devices are proliferating, many of which create a demand for communication over short distances at very low cost. And frequency spectrum has become a highly sought-after commodity as a result of all this activity.

Narrowband Licensed

Many end users are demanding that their communication channel provide more frequent updates from remote sites, and more data from each site. This may in some cases be accomplished by moving to license-free offers, but such options limit range and effectiveness in difficult terrain. However, with new technologies, modulation types that once were only useable on hard-wired circuits are being made available for use on VHF and UHF channels with the addition of low-cost chipsets.

In years past, narrowband licensed radios were typically considered to be very simple, with little or no processing capability. Today’s radios in most cases include powerful microprocessors, capable of running operating system firmware that can be easily upgraded. Such firmware can now include features to improve channel reliability. Performing retries of data packets is considered a basic feature, while more advanced features are being made available continually. For example, Dynamic radio data rate, token-grant channel management and advanced diagnostic capabilities.

In development or being discussed are yet more features for the enhancement of precious narrow-band channels. For example: the ability to automatically adjust transmitter power for reliability while avoiding interference with nearby systems; dynamic IP routing for path redundancy; enhanced filtering of unwanted network traffic; ability to operate on wider channels for more speed (eg 50 kHz or more) where allowed; and always more complex modulation types. (eg 256 QAM)

Here are some speed vs bandwidth options available today, as examples of how far narrowband systems have come:

• Trio's Q data radios (as of firmware 2.6.0) can provide up to 80 kbps in a 12.5 kHz channel, or 160 kbps in a 25 kHz channel. Higher speeds are coming with wider channels.
• Competitor #1: Capable of an over-the-air data rate up to 166 kbps in a 50 kHz channel.
• Competitor #2: Up to 80 kbps in a 12.5 kHz channel. Up to 576 kbps in a (rare) 100 kHz channel.
• Competitor #3: Capable of up to 1.7 Mbps in a (very rare) 300 kHz channel.

Where possible, the greater bandwidth can allow some models to operate at speeds equivalent to many license-free products. Note however that there are issues with higher data rates in licensed radios:

• Wider channels are difficult, or sometimes even impossible, to acquire depending on the region.
• A higher data rate in any given channel width comes with reduced receiver sensitivity, and typically also lower average transmit power. This results in shorter maximum link distances.

Another item of note is the number of frequency bands provided by some vendors. These may include the use of licensed spectrum anywhere between 135 MHz and 960 MHz. Greater frequency flexibility allows use in more regions, and locations where more popular bands are over-utilized.

In opposition to the push for greater data rates on narrow-band wireless systems is a realization that bandwidth is limited. There is continually more demand for channels. As a result, the typical licensed narrow-band channel raster will in the relatively near future be cut from 12.5 kHz to 6.25 kHz. (just as the raster was cut from 25 kHz to 12.5 kHz some years ago) New narrowband radios must be ready for this transition, as it is likely to occur within the lifespan of many radio systems being sold today.

Please "stay tuned" for Part 2 of this blog series.