After the read, you will know what is Sub-1GHz, and what is Sub-1GHz ISM frequency band.
What is Sub-1GHz?
Sub-1Ghz RF operates in the ISM spectrum bands below Sub-1Ghz.
Although the new generation of 5G communication is heading towards higher frequency, such as the band above 5GHz, or even up to 28GHz, 30GHz, etc., in fact, there is another trend of wireless communication, which is heading towards lower frequency, that is, the band below 1GHz, called Sub-1GHz.
The so-called Sub-1GHz, literally speaking, refers to the wireless communication below the 1GHz band is counted, but in practice, this is not the case, but deduct many existing applications and standards to count.
What are Sub-1GHz ISM frequency bands?
The Sub-1Ghz ISM frequency band is becoming very popular for IoT applications needing long-range and low power.
These high-performance Sub-1GHz ISM frequency bands cover a wide frequency range, including 169MHz, 315MHz, 433MHz, 470MHz, 868MHz, 915MHz, 928MHz, and 960 MHz, etc. in the license-free industrial, scientific, and medical (ISM) frequency bands.
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First of all, we should deduct the TV white space (Television White Space, TVWS) of the analog TV, as small as 54MHz, and as large as 890MHz, and will use the 698MHz to 890MHz band after changing to digital TV.
In terms of LTE, FDD LTE also uses 13 bands below 1GHz, generally between 700MHz and 900MHz, but there is a band as low as 462MHz. and TD-LTE, which is partial to high frequency, also has a band below 1GHz, 703MHz.
After deducting the above, the Sub-1Ghz ISM frequency band in real IoT applications is mostly 315MHz, 433MHz, 868MHz, 915MHz, etc. Some countries also allow the use of the 169MHz band or 779MHz Sub-1Ghz ISM frequency band for mainland China.
Even these Sub-1Ghz ISM frequency bands, in fact, there have been other wireless communication standards used, such as the industry has been developed and implemented for 10 years ZigBee, that is the use of 2.4GHz, 915MHz, 868MHz Sub-1Ghz ISM frequency band, the latter two below 1GHz.
And Google/Nest Labs proposed home IoT wireless communication technology Thread, has stated the use of the same underlying technology with ZigBee, that is, IEEE 802.15.4, which means that the existing ZigBee communication chip has been supported, in theory, as long as the firmware update, you can switch to thread communication, so also use and 868MHz, 915MHz Sub-1Ghz ISM frequency band.
However, ZigBee and Thread already belong to the field of IoT technology, which is already the original intended application of the Sub-1Ghz ISM frequency band.
In addition to ZigBee, Thread, IEEE 802.11ah standard is also locked below Sub-1Ghz ISM frequency band IoT applications, wireless sensor network (WSN), and other applications.
Of course, below Sub-1Ghz ISM frequency band also contains analog AM radio 540kHz ~ 1,600kHz (1.6MHz), FM radio 88.1MHz ~ 108.1MHz, also contains wireless charging WPC Qi 110kHz ~ 205kHz, or A4WP 6.78MHz, NFC and RFID sensing 13.56MHz Sub-1Ghz ISM frequency band, but because these frequencies are too low, except FM is almost all less than 100MHz, so almost can be omitted and not conflicting.
Therefore, even if we really talk about the application of IoT transmission below the Sub-1Ghz ISM frequency band, there are four categories that need to talk about, one is the most popular industry-standard ZigBee (widely used), and the second is the exclusive type of Sub-1GHz transmission applied by each industry, the third is just recently started, only for the home IoT Thread, the fourth is expected to be in place in 2016 IEEE 802.11ah The fourth is IEEE 802.11ah.
IEEE 802.11ah is established in the hope that the industry will abandon the proprietary Sub-1Ghz ISM frequency band, but at present, it is not optimistic, because 11ah is only a consensus standard that most of the industry can accept, and the existing proprietary chip performance has exceeded this standard, and it is expected that even if the standard is released, the speed of abandoning the proprietary will be slow, especially in some industrial applications, which are especially concerned about better communication. Especially in some industrial applications, especially for better communication performance and longer replacement cycles.
The above four categories have not yet talked about LTE, in fact, LTE is also setting up a new communication standard to support the Internet of Things, that is, MTC (Machine Type Communication), so there are five types of IoT communication below Sub-1Ghz ISM frequency band because as mentioned above, LTE has at least 462MHz, 700MHz ~ 900MHz available.
In addition, ZigBee, Thread in the home IoT competition still has Z-Wave, which also uses 868MHz ~ 956MHz Sub-1Ghz ISM frequency band.
In addition, the United States after President Obama took office proposed the smart grid (Smart Grid), also after the IEEE is responsible for the development of the smart utility network (Smart Utility Network, SUN) standard, that is, IEEE 802.15.4g, is also the same use of less than Sub-1Ghz ISM frequency band, also belongs to the industrial application of the Internet of things.
Must we use the Sub-1Ghz ISM frequency band?
For one thing, the low frequency can be used to achieve a relatively large area coverage at a lower cost, so as to support a wide range of sensing nodes, while the transmission volume of each node is not large, and the Mbps transmission rate of the low-frequency band is sufficient to cope with.
As Nest Labs said, the 2.4GHz band is too crowded, including microwave ovens, Wi-Fi, and Bluetooth are all used, so Thread expects to use other frequency bands outside of 2.4GHz to accelerate the realization of home IoT.
At present, the only IoT communication that does not use less than Sub-1Ghz ISM frequency band is afraid that only Bluetooth remains. 4.1 version of Bluetooth also began to support Mesh-type network, which is the necessary foundation to support IoT, but Bluetooth is still mainly 2.4GHz, and see whether its future development will also follow the use of Sub-1Ghz ISM frequency band.
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