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I just want to understand what I imagine is a very basic concept: at what point would my wireless router become the bottleneck on my network?

Network:

  • ISP - 20mbps download
  • Wireless router - belking n600 db (max link rate, 300mbps)

Questions:

  1. How does link rate relate to actual data transfer? The belkin link includes this description:

The standard transmission rates—300Mbps (for 2.4GHz), 300Mbps (for 5GHz), 54Mbps, and 11Mbps—are the physical data rates. Actual data throughput will be lower and may depend on the mix of wireless products used.

  1. Will I never reach the max data transfer on my wireless router considering my download throughput is 20mbps (is 300mbps max link rate relevant here, or should I consider something else to calculate if 20mbps is enough for me)?
  2. Concerning channel width, this article explains wireless transmission is not restricted to one frequency (channel?). Is it good to leave wireless router settings to 20MHz if switching to 40MHz can mean more interference? How can I measure if 20MHz or 40MHz is better for me?
  3. Wikipedia explains that the 802.11n standard can achieve 72mbps on a 20MHz channel. If I only get 20mbps from my ISP, does this mean the ISP will always be the bottleneck? If I get 100mbps from my ISP, will my router at 20MHz then become the bottleneck (justifying switching to a 40MHz channel)?
  • Don't forget to consider the speed of the client connecting to the router. I.e. The wifi card in the computer. Other bottlenecks with wifi are range and channel congestion to name a few. – Tyson Nov 4 '15 at 3:16
  • @tyson thank you. Is there a resource you can point me too so that I can understand how to measure those? – smilebomb Nov 4 '15 at 3:18
  • If you give me a link where did you read it, maybe I can explain it to you more understandable – Divin3 Nov 4 '15 at 5:30
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The wireless will become the bottleneck in your network when it's the slowest point in your connection. There are, in the main, 2 usage cases to consider:

  • LAN connections - i.e. if you are copying between devices on your network. In this case the Wireless connection will almost always be the bottleneck at the kinds of speeds you are talking about as computer internals are faster.

  • ISP/WAN connections. If your ISP connection is faster than the actual speed you are getting through the wireless connection, then the Wi-Fi connection will be the bottleneck. (On a 20 mbit per second connection, provided your wireless signal is strong and there is no interference, the ISP interface will be the bottleneck - However that is not always the case).

1. The link rate for Wi-Fi bears very little relationship to anything - it is a theoretical value that can only be achieved in extremely controlled conditions over short distances - you will not see it in real life. Figures vary greatly, but 50% of the maximum performance is probably about as good as it gets most of the time.

The thing with Wi-Fi is that the further the devices are, the slower the connection. Similarly the more devices sharing the connection the slower it is, AND, IMPORTANTLY, OTHER NETWORKS AND DEVICES in the same (and nearby) frequency bands will decrease your performance. Also the size and direction of your antenna(s) - in the case of your Belkin router this is a big concern, as well as the firmware.

Also, if you use older standards you will get lower throughput, which is where the 54Mbp and 11Mbps comes in - they were the maximums for older technologies (802.11b and 802.11g). Your router obviously supports 802.11n as well as the older, slower standards, which is pretty standard. [If your computer is 802.11n - which it most likely is, you can ignore everything about 54mbps and 11mbps on the box.]

2. If your wireless signal is strong - better than about 40 mbits connection speed, without too much interference - and this is not a big ask - your Wi-Fi will not be the bottleneck. If you are at the limits of connectivity it will be. (multiple walls, distance, etc.)

3. If both devices support 40MHz (which is probable), 40 MHz will offer you better throughput - ESPECIALLY under noisy conditions. (Imagine you are at a noisy party, if someone is talking in a low tone, you may not hear them, while if they are speaking in a higher tone you might - or vice-versa. More bandwidth = more tones to hear and get a signal from). Because 40MHz gives you more maximum bandwidth it gives you more maximum throughput. (If you were in an office environment where you needed to cover a large area and controlled all sources of noise, you may not want 20MHz). As an aside, if you can't get a connection with other devices when using 40MHz, drop it to 20MHz - I have seen this as an issue, but only on some equipment.

You can measure if 20MHz or 40MHz is better for you by transferring data to and from another computer on your network which is connected via Wi-Fi. You will find that 40MHz is better though. Wireless transmission is not restricted to one channel, but most devices (including 802.11n devices which are common Wi-Fi) only use 1 or 2 channels to "play nice" with neighbours. Also, channels "overlap", so if your neighbour is on channel 1, and you are on channel 2, you will get a lot more interference than if you are on channel 4 or higher (but less then if you were both on channel 1). There are only 3 (or maybe 4) non-overlapping channels depending on where in the world you are (slightly different frequencies are allowed)

4. If you could actually get 72mbps on your 20MHz channel, that would be correct. In the real world you can never hope to get anywhere near it, although you should still get more than 20Mbit, in which case the ISP will be the bottleneck. If you get 100Mbps from the ISP, then yes, your Wi-Fi device will be a bottleneck. Unless you have an agreement with your neighbours about bandwidth allocation and it's an issue, use 40MHz.

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First of all, lets start with the basics:

What does it mean when a router is described as being N150/N300/N600/N750/N900?

The 802.11n standard defined specifications for Wi-Fi devices to support multiple radios and antennas that can transmit/receive multiple data streams, also known as spatial streams. You may have seen notation or reference of the send and receive antenna configurations shown as 1x1,1x2, 2x2 or 3x3, etc...
These configurations simply indicate different combinations of transmit and receive antennas are being used in the 802.11n device. Basically, with more antennas and streams, users will experience better overall wireless performance.

Basically N600 means that the router will be capable of 300 Mbps on 2.4 GHz and 300 Mbps on 5 GHz
Note: 2.4 GHz will result in a longer range compared to 5GHz, however with 5GHz you will be able to achieve a higher bandwidth.

What does the Mbps mean?

The different speeds (150/300/450/600) are achieved with different channel widths, 20/40/60/80 MHz respectively. Larger channel widths do not result in higher range, just faster speeds at close range. Transmission power or Range is not related to the channel width.

"Up to 54Mbps" supports the 802.11g & 802.11b standards.
"Up to 145Mbps" and "Up to 300Mbps" modes support the 802.11N specification and use 20MHz and 40MHz bandwidths, respectively.
"Up to 300Mbps = 40Mhz" will provide the maximum performance in most cases.
"Up to 145Mbps = 20MHz" may work better in areas with more interference from other access points.
"Up to 450Mbps" = 60Mhz, "Up to 600Mbps" = 80Mhz.

source

If your ISP limits you to 20 Mbps that means that you will never be able to get a higher bandwidth on the internet independent of the router you are using.

Note that you can get the maximum out of your wireless speed within your LAN

Read more: https://en.wikipedia.org/wiki/Bandwidth_(computing)

Update:

Frequency channel is useful only in case of multiple wireless broadcasting routers or other interferences. For example if the neighbours router interferes with your router, the router can change it's channel meaning that the frequency will slightly change to avoid interference. This usually happens automatically and the router will find the best channel, but can also be set manually. In other words, you don't have to bother with this.
However if you want to make sure that there is no interference, the easiest way is to get or borrow a phone with Android, download a free program that can check the wireless signals and you will get a nice graphical interface showing all of the wireless access points that are broadcasting. If there are no overlapping, and the signal is fine, there should be no problem.

The other thing that you are looking for is called MIMO

If you want to support your clients with a lag free streaming possibility, you should read this first: http://www.techhive.com/article/2928725/how-mu-mimo-wi-fi-works.html

  • Let me see if I understand you correctly. If I had 6 users streaming HD video on their phones in this setup I described in my post, then any disruption in the video would be a result of not enough throughput from the ISP; the wireless router would never be the issue? – smilebomb Nov 4 '15 at 14:20
  • @jefffabiny - according to this site: soundandvision.com/content/… HD streaming requires at least 4.5 - 9.0 Mbps for HDX 1080p video. In theory, the bandwidth given by the ISP should be enough for 2 users. But what do you exactly mean by streaming? Will they be downloading HD videos or be recorded and uploaded to the internet? Beware that these are two different sides and also the ISP usually advertises only their download speed, the upload speed that they give is usually lower. – Divin3 Nov 4 '15 at 14:45
  • I mean something like netflix. I am not concerned about upload at the moment (I understand that difference). So if I changed ISPs to one the provides 100mbps download, then in theory I could have 10 users streaming HD video wirelessly and my wireless router should be able to handle that traffic without issue, because my router has 300mbps link rate? – smilebomb Nov 4 '15 at 14:53
  • I have edited my post to make my questions more clear. – smilebomb Nov 4 '15 at 15:19
  • @jefffabiny - updated my answer – Divin3 Nov 5 '15 at 6:39

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