Why Can Sub-1G Still Get a Signal Through Three Walls? A Look at the "Silent" Wireless Technology

Anyone who has set up Wi-Fi knows the feeling: the router is in the living room, but the signal weakens as soon as you enter the bedroom—two walls away and the video starts buffering.

But interestingly, the smart electricity meter in your basement, the smoke alarm on the garage ceiling, and the door sensor in the hallway are also "connected," staying online year-round, and running for ten years on a single battery.

They don't run on Wi-Fi or Bluetooth, but on a technology family with very low visibility: Sub-1G, wireless communication operating in frequency bands below 1GHz.

Over the past two years, the IoT spotlight has been on 5G, Wi-Fi 7, and SparkLink, with few mentions of Sub-1G. But from smart meters to various low-speed sensor networks, Sub-1G carries one of the largest volumes of low-speed connections globally.

01 Halve the Frequency, Double the Distance: Three Physics Calculations

Sub-1G's "long range" isn't achieved by brute-forcing higher power—it's a gift from the laws of physics.

Calculation One: Path Loss. The attenuation of wireless signals propagating through space follows the free-space path loss formula, with loss proportional to the logarithm of frequency. Transmitting the same 100 meters, a 433MHz signal loses about 65dB, while 2.4GHz loses about 80dB—a 15dB difference, equivalent to roughly a 30-fold power gap.

Every 3dB increase in transmit power roughly doubles current consumption. In other words, if a 2.4GHz device wanted to match Sub-1G's coverage, the battery would give out first. TI's classic Sub-1G chip, the CC1350, draws only 15mA at +10dBm transmit power and can transmit over 20 kilometers in line-of-sight conditions.

Calculation Two: Wavelength and Diffraction. The wavelength of 433MHz is nearly 69 centimeters, while 2.4GHz is only 12.5 centimeters. The longer the wavelength, the easier it bends around obstacles—just as a subwoofer's sound passes through floors, while a tweeter can't be heard clearly through a door.

Measured data supports this: a typical brick-and-concrete wall attenuates 2.4GHz signals by 10-15dB, but only 5-8dB for 433MHz. This is why smoke alarms installed two floors down still communicate reliably over a Sub-1G network.

Calculation Three: Narrowband Sensitivity. Sub-1G solutions typically use kHz-level narrow channels, concentrating energy into a very narrow spectrum. Higher power spectral density makes it easier for the receiver to pull signals out of noise. Sub-1G receive sensitivity is generally below -110dBm, with LoRa modulation reaching -146dBm, while 2.4GHz typically only achieves -90 to -100dBm.

The trade-offs must be stated clearly: narrow bandwidth, low data rates (typically 0.3kbps to a few hundred kbps), high latency, and unsuitability for high-speed mobile scenarios. Sub-1G is a long-distance champion, not a sprinter.

02 Frequency Map: The Global "Public Green Space"

Sub-1G mainly uses ISM license-free bands—no fees to carriers, no license applications, analogous to the "public green space" of your 2.4GHz Wi-Fi.

But the green space locations differ by country: China allocated 470-510MHz and other bands, Europe uses 868MHz, North America uses 902-928MHz, and Japan uses around 920MHz. The lack of global frequency harmonization is the biggest pain point for Sub-1G overseas deployment—the same product needs re-tuning for export.

Compare this to 2.4GHz: that's the real downtown—Wi-Fi, Bluetooth, Zigbee, and microwave ovens all crammed together, fighting each other. Sub-1G bands have fewer vehicles and wider roads, plus regulations limit duty cycles, so interference is naturally lower and connection reliability is actually higher.

03 Protocol Family: The Main Players

Sub-1G isn't a single protocol—it's a family.

LoRaWAN is the king of private deployments, with one gateway managing thousands of nodes. It's favored by agriculture and campuses, with the most mature ecosystem. Coverage can exceed 15 kilometers, rates range from 0.3-50kbps, and it uses a star topology.

Wi-SUN is the mainstay of smart grids, based on the IEEE 802.15.4g standard with native IPv6 support. Every node can act as a router relay, and it's used in electricity meter deployments in North America and Japan. Mesh multi-hop coverage is about 4 kilometers, with rates of 50-400kbps.

Wi-Fi HaLow (IEEE 802.11ah) is the family's "new money"—bringing Wi-Fi into the 900MHz band while maintaining IP protocol compatibility. An 8MHz channel can run tens of Mbps, and a single AP can theoretically connect 8,191 nodes. Its rate is two orders of magnitude higher than LoRa, making it the only Sub-1G technology capable of smoothly transmitting video.

There are also Z-Wave (smart home), SigFox (simple alarms), and Wireless M-Bus (European water, gas, and heat metering), each locking into different niche scenarios.

04 2026: Three Signals of a Comeback

Sub-1G's old scenarios are already profitable: water, electricity, and gas meter reading is the world's largest deployment scenario; smoke alarms and door sensors benefit from wall penetration; agricultural sensors run 5-10 years on coin cell batteries. But in 2026, new variables are emerging.

Signal One: HaLow chips enter mature mass production. Zhuhai Taixin's TXW8301 has been in mass production since 2020, shipping stably for over 5 years, passing Wi-Fi Alliance, FCC, and CE certifications, with leading brands like Hikvision and EZVIZ already adopting it. Overseas, Australia's Morse Micro has pushed the MM8108 to 43.3Mbps, completing multi-country certifications in May 2025.

Signal Two: Major players begin teaming up. In September 2026, Morse Micro announced a strategic partnership with Quectel to launch the FGH100M module (850-950MHz, 32.5Mbps). Qualcomm serves as chair of the Wi-Fi HaLow Alliance, and MediaTek has also assembled a research team. When module giants and chip giants enter, it usually means the cost curve starts to decline.

Signal Three: Field trial data is compelling. In the Wireless Broadband Alliance (WBA) Phase 2 trials: a single HaLow AP covered over 140 measurement points in a 464-square-meter residence, with throughput exceeding 8Mbps in high-demand areas; a smart farm covered 14 acres with a single AP, still achieving 1.3Mbps at the far end; and urban areas achieved 1-kilometer radius coverage. The blank quadrant of "low power + bandwidth demand"—video surveillance, 4K doorbells—finally has an answer.

05 The Layering Logic of IoT Connectivity

Sub-1G's comeback reflects IoT connectivity moving toward layering.

Cellular networks (4G/5G) handle wide-area coverage and mobile scenarios, 2.4GHz/5GHz Wi-Fi handles high bandwidth and local access, and Sub-1G handles the places where "no one wants to run power cables and no one wants to change batteries."

These three layers aren't substitutes for each other—they each adapt to different scenarios. Sub-1G chose a path of "giving up speed to win back distance and power consumption," and thus it wins all the "slow data" scenarios.

For engineering professionals working on IoT projects, understanding Sub-1G's physical characteristics and application boundaries is more valuable than memorizing any specific parameter. The pros and cons of wireless technologies are never absolute—only scenario fit matters.

06 Final Thoughts

Sub-1G teaches us one thing: speed, distance, and power consumption form an impossible triangle. Sub-1G chose the latter two, gave up speed, and thus won all the "slow data" scenarios.

Three observation points for what's next:

HaLow consumer adoption: Cameras, doorbells, and routers are the C-end entry points. Watch which brand creates a hit product in 2026-2027.

Domestic 470MHz ecosystem: The progress of adapting China's micropower frequency policy with Wi-SUN/LoRa will determine whether domestic solutions can scale overseas.

AI edge sensing: For AI to be deployed on coin-cell devices, low-power backhaul links are essential. Sub-1G + edge inference could become a new combination.

IoT connectivity will continue to layer—cellular for wide area, 2.4GHz for bandwidth, and Sub-1G for the places where "no one wants to run power cables and no one wants to change batteries." The last category has the largest number of devices—they just don't speak up.