picking a wireless router: dual band support

[Lennart Sorensen]

On Fri, Mar 19, 2010 at 12:07:04PM -0400, D. Hugh Redelmeier wrote:
> [Warning: this is long and rambling]
> 
> I still haven't found: a clear, simple, and reliable way of finding
> the best available routers for *wrt.  One reason is surely that there
> are several dimensions that one might care about so there isn't a
> simple answer.
> 
> I just bought my first thing with 802.11n (not counting a router that
> I've loaned).  This brings into focus Lennart's insistence on dual-band
> support.  I think he is right and I'm glad he brought it to my
> attention.
> 
> What is dual band?  802.11b and 802.11g both use the 2.4GHz unlicenced
> radio band.  802.11a (limited takeup) uses the 5GHz band.  Some (by no
> means all) 802.11n systems support both of these bands.  All 802.11n
> systems seem to support the 2.4GHz band.  So dual-band as means
> supporting both of these bands.
> 
> Why does dual band matter?  Because so many things crowd the 2.4GHz
> band: baby monitors, microwave ovens (leakage), Bluetooth, etc.  See
> <http://en.wikipedia.org/wiki/Electromagnetic_interference_at_2.4_GHz>.
> The 5GHz band is less crowded.
> 
> This advantage might decline if and when dual-band 802.11n becomes
> ubiquitous.  It is perhaps telling that there is no wikipedia article
> on 5GHz interference.
> 
> I just bought a netbook that has 802.11n but is only single band.  The
> specs for this device were hardly available -- I didn't even know that
> it did 802.11n -- so I'm not disappointed.
> 
> How can you tell if a device has dual band support?  I guess that in
> most cases it is advertised as a feature if the device supports it.
> A second clue is that if 802.11a and 802.11n are both listed as
> supported, then I would think that the 802.11n will support both
> bands.

The packaging should say.

Some say 'dual band wireless'.  Some say 'simultanious dual band
wireless'.  You want the last one, not the first one.  Just listing
support for 802.11a doesn't mean it can do both bands at the same time.
It just means it has the option to use 5ghz.

> Some routers can simultaneously use both bands and some switch between 
> them.  That probably matters.  Most of the google hits for "simultaneous 
> dual-band wireless router" refer to certain Linksys devices; it may be 
> that there is a different terminology used by other manufacturers.

Dlink uses the same terminology.  I have a dlink DIR-825 rev B, which
so far to me seems like probably one of the best wireless router choices
out there.  It has support checked in to both openwrt and ddwrt, although
I don't believe either has made a release with support yet, but it will
be in future releases from both.

> I previously said that this router was a good deal:
>   <http://www.bewawa.com/tp-link-ultimate-wireless-n-300mbps-gigabit-router-w-3-detachable-antennas-wr1043nd.html>
>   <http://www.tp-link.com/products/productDetails.asp?class=&content=spe&pmodel=TL-WR1043ND>
> But it doesn't support the 5GHz band so I will no longer consider it.
> 
> It looks as if the Linksys WRT400n is the least expensive simultaneous 
> dual-band router around here (as low as $80 from Sig Electronics but 
> normally $100).  OpenWRT support looks to be coming along nicely.  But 
> other features might rule this one out: it does not support gigabit 
> ethernet.

The DIR-825 tends to sell for $140 to $150, and has all gigabit ethernet,
and a USB port.  I thought it was worth the extra money.  It also has a
pretty fast CPU (About 600MHz MIPS24k) and 32 (or sometimes 64) MB of ram.
For openwrt or ddwrt that might come in handy.  I also find linksys's
routers tend to run way too hot, which the dlink does not.  The dlink's
blue LEDs are way too bright however. :)

For the client side, I just picked up a linksys WMP600N card for my wife's
desktop to replace the WMP54G that it had before.  It uses a ralink
2860 chipset, which 2.6.32 has support for with a few bgs in 802.11g
mode so far.  There are newer drivers on ralink's site which claim to
do 5ghz as well and 802.11n.  I hope they make it into the kernel soon.
Even in 802.11g mode it already has much better signal strength and
throughput than the old card.

-- 
Len Sorensen
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