Why Sub-GHz Continues to be a Critical Piece of the Smart Home Puzzle – IoT For All
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As the diversity of smart home devices and solutions continues to grow—making our lives even more convenient and connected—understanding the communications framework underpinning them is more important than ever. We sat down with Mariusz Malkowski, director of customer success and integration, Building36 Technologies, to discuss his thoughts on why sub-GHz frequencies continue to be a critical aspect of smart home technology, as well as the future outlook for devices and solutions making use of sub-GHz.
The Genesis of the Smart Home
Ask Malkowski how long smart home technology has relied on the sub-GHz layer to communicate, and he will tell you that we first need to establish when the “smart home” really started.
“I think the breaking point for smart home was the iPhone in 2007 when consumers started wanting to do more with their handheld devices,” he said. “You will find devices 20-30 years ago that were in a smart home space, but they were probably not called smart home back then. Instead, ‘home automation’ was the big word. Back then, you could get a smart home system installed for a couple hundred thousand dollars, but it has since become much more reliable and more affordable.”
Since those early days of home automation, a proliferation of proprietary and standards-based solutions has offered consumers various options on both the 2.4GHz and sub-GHz layers. Only sub-GHz, however, provides the fundamental advantages of a more extended range, longer battery life, better reliability, and reduced crowding.
Maximizing Range and Battery Life
“Given the same power budget—the same amount of energy used—you’re going to get about double the range from Z-Wave when compared to 2.4GHz, and that’s just down to the physics of it,” Malkowski explained. “Now, that gets thrown out the window with Z-Wave long-range, where your typical range is going to be about a mile, and on 2.4GHz, you’re lucky to get 300 feet. The lower the frequency, the better the range, the better the penetration.”
A white paper published by Austin, Texas-based Silicon Laboratories expanded on this particular advantage of sub-GHz. It cited three main reasons for better range performance over 2.4GHz applications: “As radio waves pass through walls and other obstacles, the signal weakens. Attenuation rates increase at higher frequencies. Therefore the 2.4GHz signal weakens faster than a sub-GHz signal.” Secondly, it said, “2.4GHz radio waves also fade more quickly than sub-GHz waves as they reflect off dense surfaces. In highly congested environments, the 2.4GHz transmission can weaken rapidly, which adversely affects signal quality.” And finally, it said, “Though radio waves travel in a straight line, they do bend when they hit a solid edge. As frequencies decrease, the angle of diffraction increases, allowing sub-GHz signals to bend farther around an obstacle, reducing the blocking effect.”
Regarding battery longevity, Malkowski explained that sub-GHz frequencies can support up to double that of comparable 2.4GHz devices without replacement. “The same door lock from a given manufacturer with a radio frequency at 900MHz—you’re probably going get about 18 to 24 months before needing to replace that. For 2.4GHz, on the other hand, because of the nature of the communication, it’s going to be about 12 to 16 months,” he said.
To this point, the Silicon Laboratories white paper explained, “The sensitivity is inversely proportional to channel bandwidth, so a narrower bandwidth creates higher receiver sensitivity and allows efficient operation at lower transmission rates.” It continued, “In …….
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