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I have two laptops – one 8-month old Asus 1215n win7/32 containing an Atheros wireless driver, and one new Asus 1225b Win7/64 laptop containing a Broadcom wireless driver service. The new laptop is the new version of the old laptop, with twice the memory and a faster hard disk. My wireless router is a Dlink DIR-655 Extreme N, updated with the latest firmware 1.34. I have installed inSSIDer, and can see that the router is using two channels 11+7. I have also tested data throughput speeds using LANSpeedTest.

The problem is that the old laptop connects at 150Mbps with the data throughput about 77 Mbps, and the new laptop connects at 72 Mbps with data throughput about 44 Mbps. This does not seem right to me – the new laptop should be at least as good as the old laptop. I have excellent signal strength on both laptops – which are only a few feet apart – and have been careful to check all wireless parameters that I can think of on both machines, including using AES encryption.

I'm at the point where I'm looking at dual band, dual channel external USB wireless Adapters so that I can jump right to 300 Mbps connections, with hopefully something like 140 Mbps data throughput. However, I do not know if that is possible with my current D-Link router.

Can anyone suggest how I can get 150 Mpbs out of the new laptop (maybe I'm missing a setting?), or where I should go to from here? Thanks in advance.

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Can you switch the channels to 7+11? Some wireless chipsets only support the additional data channel being above the primary channel. –  David Schwartz Aug 27 '12 at 3:43

1 Answer 1

The 150 megabit/sec signaling rate is the fastest single-stream rate you can get using 40MHz channels and short guard intervals (short GI). A 72.2 megabit/sec signaling rate is the fastest single-stream rate you can get using 20MHz channels and short GI. So this suggests that both of your laptops are acting like they only have cheap non-MIMO, "N in name only" radios built into them, and one of them is managing to take advantage of 40MHz (a.k.a. "HT40", "wide channel", "two channel") operation, whereas the other is only using the narrower traditional 20MHz mode of operation (HT20)

Some devices don't use 40MHz channels in 2.4GHz even when it's available, because it eats up too much of the band and doesn't leave room for other uses of the band, such as Bluetooth. Chipsets or cards that contain both a Wi-Fi and a Bluetooth radio in the same module are more likely to care about this kind of coexistence and limit themselves to 20MHz operation in 2.4GHz.

You could look in your advanced driver settings and make sure you've enabled 40MHz operation on the new client, and make sure you've disabled Bluetooth and Bluetooth coexistence.

[I personally recommend people stay away from 2.4GHz-only products, and single-stream (non-MIMO, "N in name only") products. I feel like those products are too limiting and are a bit of a ripoff. Simultaneous dual-band APs and dual-band cards have been around for a decade, and 3-stream 450 megabit N has been around since late 2009 or so. I find it a bit shady that some vendors will sell you something and say it's "N" and be technically true, but it could be limited to the crowded 2.4GHz band and only be able to get a 65 megabit/second signaling rate which means it's not that much better than 802.11a or 802.11g from a decade ago. ]

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