WiFi Alliance Introduces 802.11ah

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.

73 thoughts on “WiFi Alliance Introduces 802.11ah

    1. me too, it is the most natural thing to happen to IoT. It will most likely wipe out Zigbees and other super expensive to licence stuff, plus the whole pile of proprietary radios.
      It will be like a combination between 2 of my favorite radios: ESP8266 and RFM69: getting a more power efficient radio directly in my router is great!

    1. Well, the 2.4 GHz band isn’t completely uniform worldwide either. You’re *supposed* to change the country setting if you travel internationally. Fortunately, most international travelers aren’t traveling with access points, and it’s the access point that sets the channel.

    2. There’s a ~900MHz band just about everywhere. It may be down at 850MHz, may be at the 915MHz used in the US, but that difference doesn’t matter much to the antennae and radio chipset.

      1. I just checked out my countries frequency allocation and they have 863-870MHz listed for short range devices, it is a strange that it is not marked as marked as an ISM band (probably because there are GSM networks directly above and below). But Thanks, I learned something news.

    1. Sometimes people get stuck on an idea (or even a number) Hopefully the protocol works across the entire spectrum of 802.11 suffixes regardless of operating frequency or data rates.

    2. According to this document, 802.11ah is meant for dense, low-power, single-hop deployments while 802.15.4 is meant for sparse, lower-power, multi-hop deployments. In another document, both protocols are compared in congested networks and 802.11ah wins out in terms of throughput, but not energy consumption.


    3. I think the major point is that 802.11 is for LAN and 802.15 is for PAN. I learned that PAN (personal area network) is for < 10m and LAN is for 10m – 1000m. Both not meant as hard lines. But this new standard is definitly in the LAN range even if the bandwidth is more like bluetooth or zigbee. With even more distance and higher data rates it would probably fall into 802.16 as these are like 10s of km with up to 1 Gbps.

  1. Oh no!
    It is a mess already with the mere 11 channels in an urban environment where gazillion people are using repeaters to get trough to their “own” access points because the neighbours are on the same channel…

    1. The problem is that there may be 11 channels, but WiFi uses three at a time so there are really only 3 non-overlapping bands available. Combine that with the fact that most base stations don’t auto-allocate their frequency based on existing traffic and you get congestion.
      With only 100k data rates AH should use much narrower channels and there should be less of an issue.

      1. I lived in an neighbourhood in amsterdam where i could count a hundred wifi networks from within my apartement of mere 55 m3. How many would that be with the range expansion og the new band?

        1. it does not matter that you can detect that many networks, what matters is that your signal sources(home laptop/phone etc) will arrive at your router with much higher amplitude than those far away neighbors and still get a good quality link. It’s your very close neighbor whose source is on the same channel as yours that you should be worried about.
          If anyone gets double the range by increased power/sensitivity, this will not make matters worse.

  2. Will this 900mhz interfere with my 900mhz phone from the late 90’s?
    It has been a very reliable phone with all other neighbors using more recent cordless models on 5.8 ghz freq.

      1. Not everyone is blessed enough to have access to reliable cell service and high speed internet. For those of us that enjoy having personal space and not being able to give our neighbors a high five across the “yard” they are most certainly “a thing”.

        It is completely depressing that a good portion of readers have no clue what a tape or a record or what a Tandy is. I’m going to laugh my ass off if the power and the internets ever go down.

          1. Hmmm… I wouldn’t want that telephone company!!! Our landline through CenturyLink kept right on working through a 10-day power outage from the ice storm in 2007 (I think that’s which one it was). And before anyone wonders why in this modern day and age we could have power out for that long…this is rural Kansas, and we are on the end of the line. :)

        1. Your “cordless” corded base station will go dark the instant the power goes out. Go look at it. It’s plugged into the wall to power the 900 mhz transceiver. And if it’s really old (pre spread spectrum) your neighbors have been listening all this time.

          1. Not old at all, early thirties.

            I realize landline won’t last long, they are used where i live because the cell service is crap. I will find it funny when the power goes off because we as a society are always trying to progress to the next shiny thing, and think that anything superseded is automatically antiquated and useless.

          2. LOL, I guess I’m getting pretty old too. I’m 18. We have a landline and use it all the time, because you have to go stand in certain spots in the house (and be lucky!) to make a call on a cellphone. And in the building I work in, there is no service good enough to make calls in it. There are two or three places you can put your phone if you want to be able to send texts. :)

  3. Go ahead, until I key up my 900 MHz radio running 30 watts. I hope I knock out every such router within a block. And if your router interferes with my 900 MHz two-way radio, you can get a letter from the FCC telling you to fix or replace it. Best regards, n0xmz

    1. Unless FCC regs have recently changed in the US regarding the 900Mhz band, the 900 MHz band armature radio users on a secondary basis, so causing intentional interference to primary users could result in you getting a letter from the FCC. In any case it’s not nice to cause intentional interference.

        1. …and secondary users (amateur radio operators, in this case) are higher on the totem pole than unlicensed WIFI users. ISM stands for industrial, scientific and medical, and none of those include WIFI. Remember, WIFI is unlicensed and receives NO protection.

    2. Think of this as a cheap way to get a 900Mhz 802.11 radio that you can put a 30 watt amp and a directional antenna on…

      So long as you can get the altitude you can get a network link to folks miles away easily.

    3. Why do you hope to render the equipment bought by all the neighbors in your block useless? Seems very childish and unnecessary. Why is your hobby more important than everyone that happens to live close to you?

  4. In the USA the area around White Sands Missile Range, where WMD are designed and built, is restricted to keep Ham Radio out. They don’t want the use of high power anywhere near their WMD. So, this should give regular consumers a break for low-power devices.

    1. FYI, generally nothing is built at White Sands: this is where missiles and other items are TESTED. You’re thinking of Los Alamos, which is between Santa Fe and the Colorado state line.

  5. Great. 433MHz is already so crowded, that it doesn’t make sense to use it for professional applications. Up to now, 900MHz is quiet, and offers higher transmitting power and data rates, therefore ideal for low and mid range sensor data and remote control. That time seems to have gone now :-(
    And only to connect everybody and their sister’s pulse bracelet to the home network.

    1. You obviously haven’t taken a spectrum analyzer to this band any time in the last few years: everything from power meters to various types of “car sensors” (I don’t remember the exact names and there are at least 2 or 3 techs) are raising the noise floor in any city (and probably most towns and probably even rural areas) dramatically. Certain radio sites (especially hi-HAAT) are now off-limits to 900 MHz ham radio repeaters because of nothing more than a noise floor so high that they are almost totally deaf!

      802.11AH is just the latest to the party: there are MANY others that have come before in the last decade or more. Interestingly for the other ham above, the FCC modified the rules to make ham radio almost tertiary (3rd in line) behind some of these; in others, possibly including the “unlicensed” (this appears to be a grey area in this band), ham radio is co-secondary or even co-tertiary.

      In case you’re all wondering, RadioLocation is the primary occupant of 902-928 MHz in Region 2, the Americas. In the USA and I think Canada, this is military radar just as PAVE-PAWS and friends are primary in 70cm / 420-450 MHz. I believe there is also some non-military FAA stuff here as well. The FCC rules on ham radio restrictions on 33cm around certain military installations is very telling and indicates it’s used for a lot more than just radar there just as the military’s use of what will become the AWS-3 blocks / bands (there are apparently gaps where incumbents won’t be moved).

      Hope this helps.

  6. So it’s basically Ricochet but you treat it like packets rather than pipes. Cool. About time we had something that took the other end of the range-vs-throughput tradeoff. About 15 years late, if y’ask me, but better late than never.

  7. Being UK based, I’m looking at this with a pinch of salt, the spectrum in the UK (esp. London) is so congested for radio microphone use (and we just had a huge move due to 4G mobile) that I doubt ah or af will be legal over here.

  8. HaD took the bait (again)! 802.11ah has been around for YEARS. It seems the WiFi alliance is just trying to resuccitate it again by hyping it with the “Internet of Things” baloney.

  9. Why this new standard should get more attention from the manufacturers than 802.11af?
    The “unused TV whitespace” sounds like a more clean spectrum than the 900MHz band and should penetrate a little more through the wall being at lower frequencies.

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