Understanding 2.4 GHz, 5 GHz and 60 GHz wifi in the US|
duckware.com/wifi -- January 15, 2018 -- Version 3.0a (2018/02/19)
Are you looking to upgrade your router to take advantage of faster Internet speeds wirelessly? If so,
then this paper should help you to understand current wifi technology, and make an
educated upgrade decision.
R7800 (AC2600) Nighthawk X4S
Problem: Wifi spectrum is a shared resource. Any number of access points can share the
SAME wifi spectrum. But because wifi use has exploded over the last few years
(tablets, notebooks, smartphones, TVs, Blu-rays, thermostats, etc)
the wifi spectrum is overcrowded. And when combined with ISP internet speeds now often
faster than fast ethernet (100Mbps), wifi speeds
are not keeping up.
Solution: The industry solution is a rapid move from the old
802.11n 2.4 GHz wifi spectrum to the much newer 802.11ac 5 GHz spectrum, where
speeds are much faster, due to more available spectrum (over seven times as much) and MIMO.
A real world test:
You are looking at a very expensive AC5300 router (up to 5300 Mbps) -- but what speed can
you really expect to get from it? This section explains how the
maximum real-world speed to/from an Apple iPhone 7 or Samsung Galaxy S8 from/to an
AC5300 router is only 357 Mbps! Or, if using a 4x4 MIMO client device, the speed will
be 715 Mbps.
Not bad at all, but probably not as high as you expected.
||AC5300 4x4 Router to 2x2 Client
(at a distance of 23 feet)
5300 → 2166 → 1083 → 866 → 650 → 357
||AC5300 4x4 Router to 4x4 Client
(at a distance of 23 feet)
5300 → 2166 → 1733 → 1300 → 715
5300 → 2166: Advertised router speeds are for ALL bands:
Router manufacturers combine/add the
maximum physical network speeds for ALL wifi bands (usually 2 or 3 bands) in the router to produce a single
(grossly inflated) Mbps number. But the only thing that really matters to you
is the maximum speed of a single 5 GHz band (using all MIMO antennas).
5300 is just 1000 + 2166 + 2166, where 1000 is the 2.4 GHz band speed and 2166 is the 5
GHz band speed.
2166 also indicates that this router is a 4x4 MIMO router (by looking
for that number in the speed table, right).
2166 → 2166: Channel width:
Router manufacturers cite speeds for 2.4 GHz using 40-Mhz channel widths,
but a 20-Mhz channel width is more realistic (that cuts cited speeds in half).
For 802.11ac, speeds are typically cited for an 80-Mhz channel width, which all
AC clients are required to support. But if cited speeds are for a
160-Mhz channel width, cut the cited speeds in half.
2166 → 1083: Client MIMO capabilities:
Which MIMO column do you use in the wifi speeds table (right) -- The MIMO of the router
or the MIMO of the client device? You must use the minimum MIMO common to both devices
(often the client). So if you have a 4x4 router, but use a 2x2 client
(like the Apple iPhone 7 or Samsung Galaxy S8) to connect to it, maximum speeds will be
instantly cut in half (2/4) from cited router speeds.
Wi-Fi specifications for iOS devices (# in "Spatial streams" column is MIMO level)
1083 → 866: Client QAM capabilities:
Router manufacturers may cite speeds for 1024-QAM, but no client device today supports 1024-QAM.
And even if they did, you would need to be VERY close (just feet) from the router to get this crazy high QAM level.
So reduce to a much more realistic maximum of 256-QAM 5/6.
Android PHY Network Speed
Windows PHY Speed
866 → 650: PHY speed (distance from router): Router manufacturers love to cite the maximum PHY speed possible,
which you will only when you are very close (just feet) to the router. But as you move further away
from the router, speeds gradually decrease.
The 'distance' issue is represented by rows in the PHY speed table (seen upper right).
At just 23 feet away from the router (a very typical distance), 64-QAM 5/6 was
actually observed, so use that.
TIP: Find the current physical (PHY) network speed, which should correspond
to a number in the table (far upper right). On Android phones, go into "Settings / Wi-Fi", click on the
connected network, and find the 'Network Speed' (example right). On Windows, go to
the "Network and Sharing Center", click on the wifi connection, and find the "Speed"
in the status dialog that pops up (example right).
650 → 357: MAC efficiency: What is the
overhead at the network level? All of the speeds we have discussing so far are for
PHY (physical) network speeds. Due to wifi protocol overhead, speeds at the application
level are around 55% the physical network level!
So 55% of 650 is 357 Mbps.
If you don't find the PHY speed in the table, look up the PHY speed in the full
Modulation and Coding Scheme (MCS) index.
Just Google 802.11ac MAC efficiency to understand this issue.
357 → ???: Interference:
So, the final number is 357 Mbps for a 2x2 device, but only if your device gets to use the
wifi channel 100% of the time. Other wifi users (either local, or even
neighbors on the same spectrum) will decrease your speed by an unknown amount.
Results: 2x2 MIMO devices get a real download speed of 357 Mbps -- dramatically
lower than what is advertised by router manufacturers. 4x4 MIMO devices will get a real
download speed of 715 Mbps from this 4x4 router.
A lesson learned: The two critical factors that impact and determine
maximum real-world speed for a single client are:
(1) lowest common MIMO level support and (2) MAC efficiency.
The bottom line: The AC#### naming convention (AC1900, AC2600, AC5300,
AC7200) used in the router industry is nothing more than marketing hype/madness.
It implies (incorrectly) that the bigger the number, the better the router.
A final note: Your results will vary. But you can eliminate many of these steps
just by going directly to the PHY network speed reported by your client device and then taking
55% of that value as your 'maximum speed' estimate.
MIMO: What is driving the dramatic increase in wireless (wifi, cellular, etc) speeds
in the last few years is MIMO (multiple input, multiple output), or spatial multiplexing -- by using
multiple antennas. Most smartphones today are capable of 4x4 cellular MIMO -- so they
are four times as fast as a single antenna phone.
What is the big deal: The reason MIMO is such a huge deal is because it is a direct
capacity multiplier (x2, x3, x4, x8, etc) without using more spectrum.
This is accomplished by simply using more antennas.
The only minor caveat, of course, is that BOTH the transmitter and receiver must support MIMO.
And if each supports different levels of MIMO, the minimum MIMO level common to both devices
will be used. For example, a 2x2 MIMO tablet connecting to an 8x8 MIMO router will
only use 2x2 MIMO (however, the router will use the other antennas for diversity and beamforming).
Notation: You will often see the MIMO level written as NxM:S,
where 'N' is the number of transmit antennas, 'M' is the number of receive antennas,
and 'S' (an optional component) is the number of simultaneous 'streams' supported.
If the 'S' component is missing, it is assumed to be the minimum of 'M' and 'N'.
OR, some devices will just say '2 streams' (for 2x2:2) or 'quad stream' (for 4x4:4).
Diversity: Multiple antennas improve link quality, and increase range. With multiple
antennas receiving the same transmitted signal, the receiver can recombine all of the received
signals into a better estimate of the true transmitted signal.
Beamforming: A 802.11ac "wave 2" technology that uses multiple antennas to 'focus'
the transmitted RF signals directly to a device (instead of just broadcasting
the signal in all directions).
Comcast XB6 gateway - 8x8 MIMO
Example: If an 80 Mhz 802.11ac channel yields 325 Mbps, then 2x2 MIMO yields 650 Mbps, 3x3 MIMO yields 975 Mbps,
4x4 MIMO yields 1300 Mbps, and 8x8 MIMO yields 2600 Mbps -- all on the same 80 Mhz channel!
Many smartphones in 2017 are 2x2 MIMO for wifi, with it rumored that many smartphones in 2018 will
switch to 4x4 MIMO. Comcast already has a 8x8 gateway capable of real actual gigabit wireless
throughput -- the only cavaet is that you need an 8x8 client to get that speed!
802.11n 2.4 GHz is a legacy (obselete) wireless band that has been replaced with 802.11ac 5 GHz. This section
is provided for reference only. You should be using 5 GHz for all of your 'new' wireless internet devices. Only
use 2.4 GHz when you are forced to -- by a device that does not support 5GHz.
A brief look at the past wifi generations:
|First||802.11||1997||up to 2 Mbps|
|Second||802.11b||1999||up to 11 Mbps|
|Third||802.11g||2003||up to 54 Mbps|
|Fourth||802.11n||2009||up to 600 Mbps|
Spectrum: There is 70 Mhz of spectrum (2402-2472 Mhz) available for wifi to use in the U.S.
in the 2.4 GHz band, supporting three non-overlapping 20Mhz channels.
|2.4 GHz wifi channels (US)|
|Channel||Mhz center||20 Mhz channel|
|microwave ovens: 2450 Mhz ±?MHz|
There are eleven 2.4 GHz wifi channels, but you can't use them all:
In the US, wifi routers allow you to set the 2.4 GHz wifi
channel anywhere from 1 to 11
So there are 11 wifi channels, right?
NO! These eleven channels are only 5Mhz apart --
and it actually takes a contiguous 20Mhz (and a little buffer Mhz between channels) to make
one 20Mhz wifi channel that can actually be used. Because of this, in the US, these restrictions
result in only three usable non-overlapping 20Mhz wifi channels available for use
(1, 6, or 11; seen right).
Shared spectrum: All wifi devices on the same spectrum must SHARE
that spectrum. Ideally, all wifi devices decide to operate on either channel 1, 6, or 11 -- the
only non-overlapping channels. Then all devices operating on a channel share that channel.
But I have seen routers operate on channel 8, which means that router is being a 'bad citizen'
and interfering with channels 6 and 11.
Protocol Overhead: Each 20Mhz wifi channel has bitrate of around 72Mbps, but due to wifi
protocol overhead, you only get to use just slightly over half of that (around 50% to 70%).
Channel bonding / 40Mhz channels: This is the biggest marketing rip-off ever! Routers
can then advertise 2x higher speeds, even though in most circumstances, you will only get
1/2 of the advertised speed! For example, The Netgear N150 (implying 150Mbps), which is the
result of taking TWO 20Mhz wifi channels and combining them into one larger 40Mhz channel,
doubling the bitrate. This actually does work, and works well BUT ONLY in 'clean room' testing
environments (with no other wifi signals).
However, for wifi certification,
the required 'good neighbor' implementation policy prevents these wider channels from being
used in the real world when essentially the secondary channel would interfere with a neighbor's
wifi -- which unless you live in outer Siberia, you WILL 'see' neighbor's wifi signals and
the router will be required to automatically disable channel bonding!!
Or, if there is a single 20 Mhz only client that connects to the AP, the AP will
(should) drop from 40 Mhz operation to 20 Mhz operation, disabling channel bonding!
This situation is actually VERY likely to happen (for example, my daughter's laptop
that is only two years old).
Also, in the real world, things are MUCH more complicated, because many routers
don't always follow 'good neighbor' standards
Interference: The entire 2.4 GHz space is plagued by interference, or other devices
using the SAME frequency range. For example, cordless phone, baby monitors, Bluetooth,
microwave ovens, etc. Microwave ovens operate at 2450 Mhz
which is right in the middle of the wifi space, and very likely impacting two of the three
non-overlapping wifi channels,
and in some cases, even all three wifi channels
20 Mhz channel, 400ns guard interval
|2.4 GHz PHY wifi Speeds (Mbps)|
|BPSK ||1/2|| 7.2|| 14.4|| 21.7|| 28.9|
|QPSK ||1/2||14.4|| 28.9|| 43.3|| 57.8|
|3/4||21.7|| 43.3|| 65.0|| 86.7|
|16‑QAM ||1/2||28.9|| 57.8|| 86.7||115.6|
How bad the interference is totally depends upon the specific microwave. Some microwaves
are very bad, while others seem to have very little impact. At one house, using the microwave
oven causes wifi clients to disconnect from the AP, while in another house, using the microwave
oven only causes a slight slowdown in bandwidth to wifi clients.
The ultimate solution: The 2.4 GHz band is just WAY too crowed. Use a dual band (2.4 and 5 GHz)
router/AP and switch over to the 5 GHz band -- for all devices that support 5 GHz.
All quality devices made in the last few years (phones, tablets, notebook computers, TVs, etc) will
absolutely support 5 GHz.
The fifth generation of wifi is 802.11ac (2013) on 5 GHz. It is currently wifi's 'state-of-the-art',
providing a maximum speed of 4.3 Gbps on an 80 MHz channel using 8x8 MIMO:
|Fifth||802.11ac||2013||up to 4300 Mbps|
Spectrum: There is 500 Mhz of spectrum (5170-5330, 5490-5730, 5735-5835 Mhz) available for wifi to
use in the U.S., supporting six non-overlapping 80 Mhz channels.
One 80 Mhz channel in 5 GHz has more spectrum than all (three) 2.4 GHz channels combined!
More info from Wikipedia
|5 GHz wifi channels (US)|
|Channel #||20 Mhz|
The 5 GHz wifi band has six 80 MHz channels (42, 58, 106, 122, 138, 155)
BUT ONLY if you have an AP that supports ALL the new 5 GHz DFS channels!.
Channel Use Restriction:
16 (seen in red, right) of the 25 channels (or 64%) come with a critical FCC
restriction (DFS - dynamic frequency selection) to avoid interference with existing devices
operating in that band (weather-radar and military applications).
Very few 'consumer-grade' access points support ALL of these 'restricted' channels, whereas many
'enterprise-grade' access points DO support these channels. More on this later in this section.
802.11h defines (1) dynamic frequency selection (DFS) and (2) transmit power control (TPC).
Understanding 80/40 Mhz channel selection: Your router will NOT present a list of the 80/40 Mhz channels to you
(eg: 42, 155). Instead, your router presents a list of 20 Mhz channels and you select one. This then becomes
the 'primary' channel (and 20 Mhz channel support). Then to support 80/40 Mhz channel clients, the router
just automatically selects the appropriate 80/40 Mhz channels as per the table seen right.
Terminal Doppler Weather Radar (TDWR): If you are 'near' a major metropolitan airport,
you might not be able to use channels 120, 124, or 128 due to use of Terminal Doppler Weather Radar
operating within 5600-5650 MHz at a peak power of 250,000 watts!
TDWR locations and frequencies.
Cisco blog post on the TDWR issue.
Range: It is true that the range/distance of 5 GHz is reduced as compared to 2.4 GHz (around 7 dBm difference at same distance),
that is a significant benefit when it comes to actual throughput! The problem with 2.4 GHz is too much range -- I always
see the SSID of lots of neighbors, and that is a very bad thing because it means that I am sharing spectrum and
bandwidth with my neighbors (interference). With 5 GHz the number of neighbor's networks I can see is dramatically reduced. Then, 5 GHz
uses a much wider channel width (80Mhz vs 20Mhz) and with a "wave 2" 4x4 MIMO access point with beamforming, you will
see actual useable bandwidth greatly increased.
The Mbps seen at the application level will be around 55% of the Mbps at the
wifi level. This is just due to wifi protocol overhead.
In a test environment, I saw 461 Mbps download speeds on a 866 Mbps wifi link
(comes out to 53%).
New Channel Plan: Here is the 5 GHz
802.11 Channel Plan
from the FCC.
Of note is that on April 1, 2014 the FCC changed the rules
for usage in the 5 GHz band, to increase availability of spectrum for wifi use.
[summary of the new rules].
Channel 165 was added (but older 5GHz clients will not be aware of this), power
levels for channels 52 to 64 were increased, and other changes.
Transmit Power: Channels 149-165 allow for both router/client to transmit at 1000mW. However,
this does not necessarily mean that these are the best channels. All other channels allow router and
client to transmit at 250mW (exception: router can transmit at 1000mW for channels 52-64). This
'reduced range' can actually be a huge advantage, because it means there is a much higher likelihood
that you will NOT see neighbors wifi channels (as frequently as 2.4 GHz channels), which translates
directly to less interference and higher wifi speeds!
Another big thing is beamforming / more antennas: After playing around
with a new 4x4 "wave 2" router, wow! A very noticeable increase in range
AND higher speeds at range. It really works.
80 Mhz channel, 400ns guard interval
|5 GHz PHY wifi Speeds (Mbps)|
|BPSK ||1/2|| 32|| 65|| 97|| 130|| 260|
|QPSK ||1/2|| 65|| 130|| 195|| 260|| 520|
|3/4|| 97|| 195|| 292|| 390|| 780|
|16‑QAM ||1/2||130|| 260|| 390|| 520||1040|
|3/4||195|| 390|| 585|| 780||1560|
|64‑QAM ||2/3||260|| 520|| 780||1040||2080|
|3/4||292|| 585|| 877||1170||2340|
|5/6||325|| 650|| 975||1300||2600|
|256‑QAM ||3/4||390|| 780||1170||1560||3120|
|1024‑QAM ||3/4||487|| 975||1462||1950||3900|
256-QAM and 1024-QAM: These are wifi modulation schemes, but they require
such an incredibly good SNR (signal to noise ratio), that in real life, you are
very unlikely to get this unless you are just a couple of feet away from the AP.
So beware, routers will advertise the Mbps for the highest QAM they support, even
though you are unlikely to ever get that Mbps rate in real-world use (especially
This observation was made based upon testing with a consumer-grade 802.11ac 2x2
"wave 1" AP. Based upon initial testing with a much higher quality 802.11ac 4x4
"wave 2" AP, I now see some times where 256-QAM 3/4 is used!
802.11ac Wave 2: The
next generation (wave 2)
of 5 GHz is already here.
With feature like MU-MIMO, 160 MHz channels, four or more spatial streams,
and extended 5 GHz channel support.
Cisco Wave 2 FAQ.
Buyer beware: Not all 'wave 2' products will support the restrictive 5 GHz DFS channels!
WiFi certification for 'wave 2' only
devices to support this -- this support is NOT required!
Interference: It is a lot less common to find devices that use the 5 GHz band, causing interference for wifi,
but it is still possible. Just Google 'Panasonic 5.8 GHz cordless phone' for an example (which uses the upper 5 GHz channels 149 - 161)
Very few 'consumer-grade' AP's support ALL 5 GHz DFS channels:
Because of the 802.11 DFS/TPC restrictions, most 'consumer-grade' dual-band routers
sold in the US don't support restricted 5 GHz channels, which means
most consumer 5 GHz devices only support a small subset of available 5 GHz channels!
Netgear: Take Netgear as an example. Only a few high-end Netgear routers support
any DFS channels at all, and those that do appear to not support one of the sixteen
20-Mhz DFS channels (144) -- which then removes one of the eight 40-Mhz DFS channels (142), and
removes one of the four 80-Mhz DFS channels (138)
from being used!
Netgear R8000: Nighthawk X6 AC3200 (wiki). No 5 GHz DFS channel support
Some business-grade AP's DO support 5 GHz DFS channels: Some business-grade 5 GHz
devices DO support the restricted 5 GHz channels, so you get the full
advantage of a LOT more channels in 5 GHz!
Netgear R6300V2: 1750 Mbps router (wiki). No 5 GHz DFS channel support
But it turns out to be even worse. That router only supports eight 5 GHz
channels, four of which Netgear recommends NOT be used. And then Netgear bonds those
remaining four channels in one 80 Mhz channel. How many other high-end Netgear
routers use only ONE (the same) 80 Mhz channel?
Asus RT-AC5300: 5300 Mbps router (wiki). No 5 GHz DFS channel support
TP-LINK Archer C5400: 5400 Mbps class router (wiki). No 5 GHz DFS channel support
Apple Airport Extreme: wiki. This DOES support DFS channels
Channels this device supports.
Marketing Hype: Most consumer routers advertise ridiculously high Mbps speeds.
For example, the Asus RT-AC5300 states "5300 Mbps". But that is a combined speed
of 2165 Mbps for one 5GHz channel, plus 2165 Mbps for a second 5G channel, plus 1000
Mbps for one 2.4 GHz channel. So the best you can get is one 2165 Mbps channel. But this is for
1024-QAM modulation, which unless you have a VERY high SNR (signal to noise ratio) -- which you
only get very close to the AP -- cut the Mbps by 6/10 to 1300. And then
protocol overhead means you might see around 45% to 65% of that, or 585 to 845 Mbps. And that is under
ideal conditions where ONLY you are using the channel. If you are sharing the channel
(with someone else in the house or a neighbor) cut down that number accordingly. And
finally, all of these numbers are for a 4x4 MIMO client. If you are a 2x2 MIMO client (instead of 4x4),
cut the Mbps numbers in half again!
All of a sudden, just plugging your computer into a Gigabit Ethernet port on your router
looks pretty good -- guaranteed 1000 Mbps to the router all of the time.
So, don't be fooled by the marketing hype of consumer-grade 5 GHz access points!
Messing up: It appears that consumer-class routers are just starting to come out with routers
that support DFS channels.
Any router older than a couple of years is very likely a
'no' to DFS, whereas any router made within the last year is a 'maybe' for DFS support.
But they are messing up! Take Netgear. They try to support DFS channels, but they mess
up by not supporting channel 144, which eliminates 17% (one of the six) of the 80 Mhz
channels! This happens on the R7800.
Netgear ProSafe Access Points: Most of the Netgear business access points do NOT
support the restricted 5 GHz channels! But I did find ONE that did.
Many Enterprise-grade AP's DO 5 GHz DFS channels: According to
this data sheet
ALL of the Ubiquiti UniFi AC models (802.11AC Dual-Radio Access Points) are DFS certified!
And prices on Amazon range from $82 (for the Lite model with 2x2 MIMO) to $294 (for the HD model
with 'Wave 2' features).
For example, I was in a Drury Hotel and from my room, I could see the Drury SSID
on channels 48, 64, 100, 104, 108, 140. So the hotel was clearly using DFS certified
5 GHz access points!
is being marketed as the 'fastest' wifi possible, providing speeds "as fast as 4.6 Gbps",
for '4K Streaming, VR Gaming and Backup' (Netgear, right), or for
transferring an hour of HD video in 7 seconds.
Dubious Netgear 802.11ad marketing
However, the huge disadvantage of 802.11ad is that is has no range and does not go through
walls. It is intended to only be used line-of-sight and has a range of just a few meters.
Range: At the same transmit power, 5 GHz has 1/2 (50%) the range of 2.4 GHz,
but 60 GHz has 1/25 (4%) the range of 2.4 GHz, as measured in free space, or 'air'!
[RF loss calculator]
Interestingly, 802.11ac products already exist TODAY that provide 4.3 Gbps
(Arris TG3482G using the
That kind of puts Netgear's marketing hype ("3X faster than 11ac") into perspective.
802.11ad may take hold in very specialized situations, but unless the range issue is
addressed, 802.11ad will absolutely NOT become a replacement for wifi for
generalized internet access.
The dirty little secret in the consumer router industry is
poor router WAN to LAN/WLAN throughput.
Because even with crazy fast wireless speeds (above 1Gbps), the WAN to
LAN/WLAN link (below 1 Gbps) is likely where you will see a performance bottleneck!
LAN to LAN -- 941 Mbps -- Great
WAN to LAN -- 340 Mbps -- BAD!
On a 1 Gbps WAN ethernet port, the maximum speed is around 949 Mbps (due to overhead),
so you will never get wireless speeds (from the Internet) above that.
Additionally, all of the 'realistic' wireless speeds we have been discussing above
assumes that there is no slow down in the router itself moving packets between
the WAN port and the LAN/WLAN ports -- but there often IS a slow down.
The router's WAN to LAN/WLAN throughput is often the limiting speed factor! Why?
Because the router itself is performing NAT (Network Address Translation), SPI
(Stateful Packet Inspection) and other taks that takes processing time
inside the router,
possibly limiting Mbps speeds!
An example: On a gigabit LAN, I tested Mbps speed between two PC's and got 941 Mbps
(very close to the 949 Mbps maximum; graph upper right). But this only tests
the built-in "switch" inside the router on the LAN, which is rated and expected to
fully support 1 Gbps speeds.
So to test router WAN to LAN speed, I connected a Netgear R7800 (an AC2600 class router) to the LAN
(via the 7800's WAN port) and plugged one of the test PC's into the LAN
port on the 7800 -- and then ran a speed test between the two PC's -- and got
an abysmal 340 Mbps (speed test uses a single socket).
When I tested using two sockets instead of one socket, the speed (roughly) doubled, meaning
that there is some limitation (or BUG) inside the router.
The bottom line: You will NOT get Gbps WAN to LAN throughput
from some consumer-grade routers!
Beware: Virtually all internet speed tests online use multiple sockets,
which will hide this router limitation.
This section has grown so much that it has been moved to its own post.
SSID: SSID is simply the network NAME. When you connect to a wifi network, you must enter
this network name (called SSID). At home, you typically will only have one router with that network name.
However, if you add another wifi access point, you want it to use the SAME network name, as this allows for wifi
roaming. Your phone/device simply connects to the strongest wifi signal with the same SSID name.
You can use different SSID names, but then you don't get roaming.
2.4 GHz and 5 GHz names: There is a big debate -- should your 2.4 GHz band network
and 5 GHz band network have the same names, or different names (often with a "-5G"
appended to the name)? If named the same, client devices choose which band to connect
to. If named differently, the end user must choose which band to connect to.
The problem with the 'same name' technique is that some client devices are 'dumb'
and incorrectly connect to the 2.4 GHz band instead of the 5 GHz band.
I had this problem with a laptop that would start out connected to the
(fast) 5 GHz band, but after a little while, would then switch
to the (much slower) 2.4 GHz band.
BSSID: This is the MAC address of the AP that your phone actually connects to
(because you can't tell which AP from the SSID).
Just use whatever method works best for you and your devices!
Channel: ALL wifi access points (in your house and visible neighbors networks)
covering the same frequency must share the wifi bandwidth. Because of this, assign channels
1, 6, 11 (2.4 GHz) and 42, 58, 106, 112, 138, 155 (5 GHz) to your AP's in a manner to best
avoid conflicts (with yourself and neighbors).
There is nothing special about channel selection. A channel is like a lane on an Interstate highway.
All cars (AP) can use the same lane (channel), but that is slow and inefficient (lanes go unused).
Everything works best when cars (AP) use all lanes (channels) -- as evenly as possible.
Best: Get a 4x4:4 (4 streams) 802.11ac "wave 2" access point (or router) that
supports beamforming and ALL six 80 Mhz 5 GHz channels (42, 58, 106, 122, 138, 155)
However, don't be fooled by the many 'consumer-grade' 5 GHz routers and access points that
only support a small fraction of the 5 GHz spectrum.
Comcast TIP: If you have Comcast for your Internet and they are already providing you with a
'gateway', contact Comcast and say that you want their new best
XB6 Wireless Gateway,
which is an 8x8:8 MIMO (eight stream!) 802.11ac device, which supports data throughput of 1 Gbps.
The only downside to the XB6 is that it appears to only support two of the six 5GHz channels
(42 and 155).
Comcast XB6 Gateway
8x8:8 (eight stream) routers are even better -- and are just starting to come out,
but they will be expensive.
Second best: This recommendation is still a work in progress, but...
If you can find a reasonable consumer-grade router that supports ALL 5 GHz channels, then
use that router. However, if not, then
(1) get a quality Gigabit capable router, which is connected to your modem/internet, and
(2) then use an enterprise grade 5 GHz access point (using wired Ethernet to your main router),
which is capable of supporting ALL available 5 GHz channels, and place the AP strategically
in your house for maximum coverage.
Beware, many Netgear 5 GHz routers (even the very high end models) only support
two 80 Mhz channels (42, 155), which means that you have a very high likelyhood
of sharing spectrum with a neighbor! Instead, take the time to find a router that
supports ALL 5 GHz channels.
Ubiquiti sells a line of "UniFi AC" access point products that DO support ALL 5 GHz
channels, and are very reasonably priced.
Then, over time, you can upgrade and replace the AP's (to upgrade to the latest technology)
without having to replace your main router (until broadband to the home passes 1Gbps, at
which point you would need to replace the router).
Which level of MIMO you select (2x2, 3x3, 4x4) for the AP depends upon your needs and
more importantly, your budget.
Or, another approach is to purchase a 'certified refurbished' top-of-the-line
consumer-grade router (so inexpensive) that does have DFS support (normally very expensive and overpriced when
compared to enterprise-grade APs).
The first step: Make sure you are connecting to a 5 GHz SSID on a channel that is not overloaded.
WiFi Analyzer Access Points
Install a WiFi Analyzer app
on your smartphone and find out exactly what channels are being used (who you are sharing spectrum with),
and then set your router to use the most unused channel. Channels 1 - 11 are 2.4 GHz channels.
Channels 36 - 165 are 5 GHz channels.
Q: I upgraded my internet speed from 60 Mbps to 120 Mbps and my wired internet speeds dropped!
The most likely cause is that not all devices in your network are 1 Gbps capable. If there are
any fast ethernet (100Mbps) devices between you and your ISP, that device becomes a 'choke point'
that will very likely cause dropped packets and speed problems.
Q: I am connected to my wifi router at 866 Mbps, but a speedtest shows only 400 Mbps?
TIP: It is very common for ISP's to provision internet modems to 110% of the advertised speed. So
if you sign up for 100 Mbps internet, your 100 Mbps network will not work, since the internet speed
is more than likely actually 110 Mbps.
Due to wifi protocol overhead, the expected throughput at the application level is
around 55% of the physical wifi speed. Sadly, the industry has done a very poor job
Q: I bought a '1733' AC wifi router, but I can only connect at 650 Mbps from my smartphone?
Router companies love to advertise maximum speeds. Looking at the 5 GHz speed
table far above, we can see that '1733' implies a 4x4 access point supporting 256-QAM.
650 is the speed for a 2x2 device at 64-QAM. The conclusion is that your smartphone is
a 2x2 MIMO device and that you are maybe 20 to 30 feet from your router. Expected application
throughput will be around 55% of that, or 357 Mbps.
Q: My speedtest proves I only get XXX Mbps?
Always try several different speed test programs, like
The very nature of the internet is that everyone will not always be fast.
I find that the
xfinity speed test
gives the most reliable results, almost all of the time
(and it had better, since Comcast is the largest broadband provider in the US).
2.4 GHz / 5 GHz / 60 GHz: Refers to the wireless frequency used by wifi.
802.11n: The specification for fast wifi (mainly) in the 2.4 GHz band.
802.11ac: The specification for faster wifi in the 5 GHz band.
802.11ad: The specification for wifi around the 60 GHz band.
AC####: AC refers to support for 802.11ac and #### is the sum of the 'maximum PHY network speed'
for ALL bands in the router (like dual-band or tri-band).
Beamforming: A standards-based (802.11ac) signal-amplification technique that
results in increased range and speed to a device. Beware earlier (proprietary) 802.11n
Dual-band: Two access points in one. Often band one is 2.4 GHz and band two is 5 GHz.
MIMO: Multiple-input and multiple-output, where 'multiple' refers to antennas.
Also known as SU-MIMO (single user MIMO).
MU-MIMO: MIMO to "multiple users" at the same time.
'N' Spatial Streams: Refers to NxN MIMO.
Quad-Stream: Refers to 4x4 MIMO.
Tri-band: Three access points in one. Often band one is 2.4 GHz, band two is 5 GHz and band three is 5 GHz.
Sometimes the third band is 60 GHz 802.11ad.
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