For the last decade or so, wireless networking has been entirely about short range, high speed communications. The type of networking needed by an Internet of things is fundamentally incompatible with WiFi, and the reason for this is due to the frequencies used by WiFi networking gear. 2.4 and 5 GHz are very fast, but cannot penetrate through walls as easily as lower frequencies.
This week the WiFi alliance introduced IEEE 802.11ah into the WiFi spec. It’s called WiFi HaLow (pronounced like angel’s headwear), and unlike other versions of 802.11, WiFi HaLow uses low frequencies for low bandwidth but a much larger range.
WiFi HaLow uses the 900 MHz ISM band to communicate, divided into 26 channels. The bandwidth is low – a mere 100 kbps, but the range is huge: one kilometer, or about four times the approximate range of 802.11n.
This is not the only WiFi spec aimed at the Internet of Things. In 2014, the WiFi alliance introduced 802.11af, a networking protocol operating in unused TV whitespace spectrum between 54 and 790 MHz. 802.11af has a similar range as 802.11ah – about one kilometer – but products and chips utilizing 802.11af have been rare and hard to find.
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