hi guys,

I'm confused... so we all know the 802.11g mode, a 54Mbps wireless link, but I have seen tons of "boosting" & extending -features, by now and I don't know which of them are usable, useful and/or can be mixed...

This started with the LinkSys WRT54GS (broadcom wifi) I bought some time ago.
This device was claimed to have a "speedboster", whatever this may be...
I found statements saying this is Turbo-G mode...

Well most of the current Atheros cards have a "Turbo-G" mode, I notice this when the madwifi-driver is loaded, anyway the madwifi driver shows this as turbo-g 54mbps for my Wistron CM9 and XR2, while there are sources on the internet which propose 108mbps to be the Turbo-G mode....

and finally my other Buffalo WHR-54GS (broadcom wifi) do have a "125mbps" mode, and I think they also call it "Turbo-G", because there'S a Turbo-G label on the surface of this router...

last but not least, some ppl told me, that super-G only exists and works with atheros cards.... huh???

So, you may be understand my confusion now....
Are these modes mixable? Which of them does bring real speed-boosting?
Can broadcom and atheros super-G be mixed?
Is the speedboser feature of the WRT54GS a super-G mode?
Which of these features are supported by OpenWRT(by madwifi?)

Actually I'm looking for the fastest possible bridge-connection between my home and my office.
I currently have two WRT54GS, running WDS in normal 54Mbps mode.

So I'm now wondering if there is a way to tweak this connection a little bit..
The following solutions would be possible:

WRT54GS -- WRT54GS (current, possible add "Speedboster"?)
CM9 --- WRT54GS
CM9 --- Buffalo WHR-54GS
WRT54GS --- WHR-54GS
WHR-54GS ---- WHR-54GS

Which of them would provide the fastest link, what do you think?
Does anyone have experiences with these "turbo" modes?

Thx a lot to everyone

A common term for what Linksys used is "Afterburner".  It goes by like 5 other names one of which is Turbo-G.

It is not related to or compatible with Super-G.

Wikipedia is your friend:
http://en.wikipedia.org/wiki/SpeedBooster

Search for Afterburner in forums and Wiki, I think just nvram set wl0_gmode=6 in WhiteRussian not sure what equivalent is in Kamikaze.    And check your signal levels, unless they are very good may not be maintaining stable 54 megs connection.  Don't expect it to double your speeds though, all this stuff fiddles with frame timings etc. on existing technology.

This is quite annoying marketing as they imply doubling of speed which is not the case if you see any review/testing of real speed improvement of these proprietary modifications.

(Last edited by vincentfox on 27 Jun 2007, 14:40)

I'll add a some notes:

There are two prevalent speed enhancement technologies.  One from Broadcom (Speedbooster) and one from Atheros (Turbo-G).   They are not compatible with each other and will fall back to standard 802.11g when talking to each other.    Key differences are that the Broadcom approach stays with the standard 20Mhz channel bandwidth while Atheros uses 40 Mhz channels.   Each has it's advantages and disadvantages.  From what I have seen the Atheros method with high end hardware can achieve 50mb/s real throughput.   Broadcom doesn't find its way on mpci cards much so there are no equivalent test for it.   Most consumer routers top out around 30 to 35mb/s real throughput on either technology.   In both cases maximum throughput is not possible when using WPA and their internal cpu can't handle both encryption and compression at the same time.

Check your facts.  Atheros is NOT Turbo-G it is Super-G.  Yes this marketing speak is very confusing.

I have much more respect for the Broadcom method.  Frame bursting tightens things up especially for single station usage it's quite good.

I *DONT* like the Atheros method because they use double the spectrum.  It's a hideous and wastefully greedy solution in already crowded frequency band.   So you already only have really channels 1, 6, and 11 that don't overlap.  3 whole channels that are non-interfering.   With Super-G if you pick channel 1 it will use channel 6 as well to deliver that doubling effect.  It takes up 2/3rds of the available unlicensed spectrum!  Fine if you live in a rural area, otherwise it is irresponsible.    If you have an interference source on channel 6, you will NEVER get Super-G speed anyhow because it can't use opposite ends of the spectrum, it widens from the channel you select into the adjacent ones up or down.   Wherever I have had influence among my friends, I warned them away from Super-G.   Atheros did later come up with something it calls "Turbo Super-G" which only confuses the marketing naming even further.

(Last edited by vincentfox on 28 Jun 2007, 02:29)

You are correct. 

The Atheros method seems to be of most benefit in the wider spectrum for 802.11a that already has 12 channels of 20 Mhz each. 

My point about throughput was that Atheros chips are available on numerous mpci cards from various manufactures with power up to 28dbm.    For outdoor long distance connections nothing in 802.11 outperforms these cards when coupled with a performance board such as the Gateworks 2348 boards.   Broadcom chips tend to stay on lower end hardware hindering its ability to take full advantage of the speedbooster.   

I agree in urban areas Broadcom's approach is more responsible.   2.4Ghz is getting very crowded.  The biggest problem I see however is not from access points & clients but from FHSS cordless phones.  These things kill the whole spectrum for WiFi.    When WiFi devices of different networks are on the same channel with each other the don't stop each other from working only maximum simultaneous throughput goes down.  802.11 is decent at frequency sharing, but it depends on what it sharing it with that will determine how much it ends up sharing vs. using.

In my small WISP, I've given up entirely on 2.4Ghz for client connections to the network.   Too often I get calls, "My internet is down."  only to find out the customer has bought a new 2.4Ghz phone.   Even though I strongly recommend against any 2.4Ghz phone when the Internet is installed.    I am gradually replacing all 802.11g with 802.11a at the CPE.   They can continue to use 2.4 for their in house AP.  At least then I can tell when they call that the connection is still good to their house.

I like Atheros, they have many good ideas. I just don't like what they did in that particular case.

Too much junk, not nearly enough spectrum in anything other than an isolate RF-cold location.  Unfortunate that there wasn't a larger chunk of spectrum carved out just for data devices way back there, instead of having to share it with every conceivable consumer device from baby monitors to X-10 wireless camera.  At my previous workplace all the 2.4 GHz phones mysteriously died and had to be replaced with 900 MHz and 5-gig phones one by one.  I don't know how that happened....

;-)

I have actually used 1,4,8 & 11 in some cases and it works okay.  If the AP's are removed from each other and I'm using directionals with good front-to-back isolation, the interference effects due to the overlap are not noticable.

I haven't used any 802.11a, too many trees here for that 2.4 is already kinda dicey.  Don't 5-gig cordless phones interfere with 802.11a or are they on different bands or better protection mechanisms?

(Last edited by vincentfox on 29 Jun 2007, 01:37)

Shame the problem doesn't also take down the phone -- it would still be a problem but at least they wouldn't be calling you about it.

Side note - 40Mhz channels will also be a problem as we start to see more 802.11n devices pop up and claim the spectrum.

So far I haven't seen any 5.8Ghz phones that cause interference.  From what I understand, FHSS is not allowed on across the whole spectrum like in 2.4.   This makes the phone manufactures get more creative about finding the clearest channel.   

I battle trees too.  Have a look at this neighbourhood: http://maps.google.com/maps?f=q&hl= … iwloc=addr
The image is old so houses aren't shown, but all there are houses all around the new roads cut through the trees.   The image is also a winter shot, so the only green is from the thick pines, everything else has dropped its foliage. 

From what I've found 5.8 works just about as good as 2.4 since higher gain client antennas are available.   For the same size package the 5.8Ghz 24dbi panel as the 2.4Ghz 19dbi panel, the results are about the same.   This is the first place I've been changing 2.4 gear for 5.8 gear.    Both are punching through the trees well.   

One thing to note, the longest link is only about 700 feet.  I set up a star network from one of the homes that had line of sight to the tower 1/2 mile away.    The farthest from the tower in the neighbourhood has three hops to get to the tower.    I always look for the least amount trees to punch trough when choosing a mounting location.   In a couple instances the mount is a tree. 

Now that we have completely hijacked this thread for a different topic, I'll comment back on the original topic and add that I the field on 2.4Ghz I never use Atheros wide band connections, there is to many interference problems.  I have enabled speedbooster on broadcom radios, but in my usage, it didn't help much where each client is capped at a max of 3mb.

(Last edited by lschweiss on 29 Jun 2007, 16:22)

Yeah back to the original poster, I think the existing WRT54GS is about as good as you can get with any cheap consumer gear.  You can tweak around with the Afterburner/frame-burst settings and see how much you can add.  To original poster, what kind of benchmarked speeds are you getting now from LAN to LAN?

I usually worry more about other tunable parameters.  Like if it's a PtP link, turning on WPA-PSK and MAC filtering to lock out other radios.  I also try changing other things like RTS not sure if they really helped or not.  Interference in my area was pretty severe so that was a bigger factor to me than anything else.  I found one link crossing my path that was using Channel 14, I believe he had found his own ILLEGAL (in the US) way to get outside the problem.

My record through thick foliage and neighborhood from one house to another, was 1200 feet. Trees all the way and my fresnel zone cutting through some houses on each side probably too.  One end had a 24 dBi grid dish on mast about 5 feet above roofline, and a 19 dBi grid dish at about 7 feet above the roof at the other.  Alignment by dead reckoning was a bit tedious, standing on the roof and looking down at a laptop with netstumbler.  That was a fun on-the-edge backhaul link I ran across the neighborhood for a couple of years. Eventually the interference got too high and I had to pull it down and find other solutions.

(Last edited by vincentfox on 29 Jun 2007, 16:53)

yeah... it's some time ago, but I'm going to report about my experiences...

I finally decided to also use channel 14, because the air here is very crowded with different wireless networks,
but none of them is using ch11 or above (properply because ch14 is not legal here :-) )
(thanks god most of my neighbours are also n00bs and many of them share channel 6.. but many other channels are already in use)

I now have this LAN-LAN bridge up with the two WRT54GS units (currently using DD-WRT, but shouldn't make much difference at all),
I put them both to G-ONLY mode with a fixed rate of 54Mbps, I enabled FastFraming& Afterburner, hided the ssid.

The link is up with a SNR of about 50 (noise up to 100, signal at ~50)
Speed is constant&fine - ~1,5MB/sec, and there is not even one ping that gets lost... very nice!

To compare: the old configuration (ch2, mixed mode, no afterburner/fast framing, dynamic. rate etc) had a transfer-speed of max. 1MB/sec (SNR was about 60)

any idea what "G-ONLY mode with a fixed rate of 54Mbps, I enabled FastFraming& Afterburner" is in terms of kamikaze? mine is a gs v1.1

or you know like.... dont answer