Unlicensed Spectrum. New Opportunities, New Challenges

8 2017 November

Wifi, WiGig, IoT, LTE-U, LAA, LBT, 5G, ISM, UNII, and more. Connectivity is exploding. The nicknames and acronyms can be confusing. Meanwhile, more of the devices we buy and use are communicating using unlicensed or light-licensed spectrum.

First, what do we mean by spectrum? In these cases, we’re referring to radio frequency (RF). In the natural world, electromagnetic waves are all around us. They’re defined by frequency, ranging from 3 kHz to Gamma rays. In the late 19th century, Guglielmo Marconi first perfected the art of harnessing these waves as “carriers” that could take information quickly from one place to the next with the use of modulation (transmit) and de-modulation (receive).1

Throughout the world, and specifically in developed countries, governmental agencies manage the use of radio spectrum for communications.2 Without getting too deep into the technical, the US has two classes of managed spectrum: licensed and unlicensed. Unlicensed frequencies here are 900 MHz, 2.4 GHz, 5.8 GHz, 24 GHz, and 60 GHz. Most WiFi operates at 2.4 GHz, though newer routers have a 5.8 GHz channel as well. WiGig (60 GHz) is beginning to take hold but is still a nascent technology.

New Opportunities – IoT, M2M

As devices operating in this unlicensed space become less expensive and more ubiquitous, this is a boon to everyone from consumers to enterprises. Think everything from home security and monitoring with footage delivered to your smartphone to industrial farms implementing zero-waste irrigation and fertilization practices through environmental monitoring and machine learning analysis. This proliferation is quickly changing the way we interact with and understand the world around us. It’s an exciting time. However, with many devices transmitting data on the same carrier signal, they can adversely affect each other’s performance. In the industry, this is referred to as interference. Analyzing how these devices interact in the real world is difficult to do, and we’ll look at this next.

The Challenges

There are two main roadblocks to efficiently measuring and mitigating interference.

Economics - the price of many IoT devices is now well below $500 at retail. Building a test lab for reference designs can easily reach into the 7-figure range. That investment makes sense when designing a low-cost product that you’ll build millions of. Recreating the lab test set up for real-world test is a cost-prohibitive endeavor.

Logistics - expensive lab equipment is generally quite large and not very mobile friendly. Shipping is costly, raises the risk of damage, and due to the size of lab equipment - field deployment becomes quite tricky, if not impossible.

A Better Way

To address both these concerns, SAF has developed a line of ultra-compact, rugged, and affordable spectrum analyzers. Spectrum Compact is an easy to use physical layer test tool with an intuitive GUI, standalone functionality for real time insight, and the ability to continuously record months of spectrum data on the device itself. The included software makes post-measurement analysis and reporting simple, and firmware updates are included for life. Battery life is over 3 hours, so external power is not a concern. SAF offers measurement solutions from 2-87 GHz. Check out www.saftehnika.com for more information.

1 https://en.wikipedia.org/wiki/Radio_wave
2 https://en.wikipedia.org/wiki/Spectrum_management

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By Daniele Zedda   •   18 February


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