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On my wifi router i have set the mode to 150Mbps, but when i connect to this router it shows only 65 Mbps on my laptop. Why it is so? Does that mean my router is not capable to transfer at 150Mbps or my laptop is not capable to receive at 150Mbps?

Laptop: Lenovo y470 ( core i7 ) [OS: Win 7]
Router: Netgear N150

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Note it says "Up to 150 Mbps". – techie007 Nov 19 '11 at 15:11
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@techie007 does that mean my router is not capable of transferring at 150 Mbps – Rakesh Nov 19 '11 at 15:43
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There are so many factors that could cause a speed decrease, and many of those are environmental (ie: a microwave, a wall, a nearby nuclear power plant, etc.), which we can't speculate on. Just keep in mind the connection is trying to remain 'stable', not 'fast', and it could be either end making these types of adjustments. – techie007 Nov 19 '11 at 16:57
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5 Answers

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Short answer: That's the best your card can do when communicating with your AP.

Long answer:

Lenovo says your Y470 contains an "Intel 1000 BGN Wireless" card. Apparently it's more properly known as an "Intel WiFi Link 1000 BGN" card.

According to the Wi-Fi Alliance's certificate for that card, it is only capable of a single transmit stream (that is, it's not actually MIMO on transmit), and it is not capable of HT40 (a.k.a. "wide", 40MHz channels). In effect, it's pretty much "N in name only". The best speed it can transmit at it 65 or maybe 72.2 megabits per second.

Your card looks like it's capable of receiving 2 spacial streams at HT20, which means that with 2- and 3-spacial stream N APs (Wi-Fi routers) it could receive at up to 144.4 mbps, but unfortunately your AP is another form of non-MIMO -- and thus basically "N in name only" -- AP. It only supports a single spacial stream, although it does support 40MHz channels. So the best signaling scheme your AP and client both support is single stream HT20, which tops out at 65 mbps with a long guard interval, or 72.2 mbps with a short guard interval.

The Wikipedia article on 802.11n has a nice table of 802.11n data rates based on the number of spacial streams, 20- or 40MHz wide channels, and long or short guard intervals.

It's sad to me that so many "N in name only" products are being sold that don't really support the flavors of N that make it shine. The 65mbps that your card/AP combination tops out at isn't that much better than the 54mbps that 802.11a delivered a decade ago.

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what the ... that means LENOVO cheated me. That's not good. – Rakesh Nov 26 '11 at 12:12
@Rakesh: No, it means that Netgear misled you. The wireless card in the Lenovo should work fine with an AP that supports MIMO. – cmorse Jan 5 at 5:52
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@cmorse Only in one direction. I feel like both his AP and his card are ripoffs, since the first-generation N gear all did 2x2:2 HT40 in both directions, establishing N as a 300mbps technology. Anything that calls itself N but isn't as fast as the oldest draft-N gear was (from way back in late 2006, no less) is kind of a ripoff. I think most people expect newer-generation products to get better, not worse. – Spiff Jan 5 at 7:09
@Spiff I didn't notice that the MIMO was only supported on transmit. I agree with you then, the card is a ripoff. – cmorse Jan 6 at 15:26
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up vote 0 down vote

Most 802.11n products will knock your throughput down by up to 80% if you use WEP or WPA/TKIP security. The reason is that the 802.11n spec states that the high throughput rates (link rates above 54 Mbps) can't be enabled if either of those outdated security methods are used.

Quoted from 5 Ways To Fix Slow 802.11n Speed on Small Net Builder

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The speed is highly dependent on the distance of your PC from the router. Since, larger distance causes higher collision and losses, hence to account for that the bandwidth reduces.

As a rule of thumb : B1 x D1 = B2 x D2, where Bi is bandwidth and Di is distance between router and PC.

And moreover as @Ampersand says, using WEP and WPA makes it still worse.

The standards 802.11 n only caps the speed at 150mbps.

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The IEEE 802.11n standard supports rates up to 600mbps. The 150mbps rate of 802.11n doesn't even use MIMO, even though MIMO was the raison d'être of 802.11n. – Spiff Nov 20 '11 at 0:31
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up vote -1 down vote

Ensure that "IEEE 802.11 n" is supported and enabled on both the router and the laptop network card. 802.11g will only go up to 54 Mbps.

Wireless will always reduce your throughput, partly because it is duplex (effectively half speed) also due to reception/interference.

Different channels represent various frequencies - these perform better or worse depending on environment. Test every channel for performance, starting with 11 which is the strongest. Scan for neighboring wifi and select a channel not too near to the strongest.

In any case, the bandwidth numbers that Windows is showing for the card are not to be trusted. They come out of a database or are a guess based on several parameters. Only a speed-test with a source that can go at the top speed of the router can really tell what are the real limits of the PC card.

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He's getting 65, which is greater than 54, so it can't be 802.11g or 802.11a. – Spiff Nov 20 '11 at 0:29
@Spiff: See the last paragraph I added in my answer. – harrymc Nov 20 '11 at 8:17
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up vote -1 down vote

Actually I have noticed that Windows 7 limits channel bandwidth to 65mbps. I have a netbook that gets 65 even next to the router and the PC only gets 130 (dual channel wi-fi). Both are running W7. The PC used to run Vista and got 300. We have a laptop that is running XP and that gets 150 (single channel).

I've noted a lot of very similar posts all Windows 7 and all complaining at a 65 top speed. Some have noted that dual-booted machines get correct speeds on alternative OS but for some reason no one has yet realised the issue is with Windows.

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