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Hardware

Supercharging Your Linksys Wireless Access Point 168

Posted by timothy from the all-i-have-is-recent-firmware dept.
kwishot writes "Xam over at www.wi2600.org has documented a relatively simple way to 'turn up the juice' on your Linksys WAP11 Wireless Access Point." Caveats: the outlined method requires a Windows box, recent firmware, and (some) bravery, but no going inside the box or special hardware.
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Supercharging Your Linksys Wireless Access Point More

Supercharging Your Linksys Wireless Access Point

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  • Ignorant Legality Question (Score:5, Insightful)

    by Uttles ( 324447 ) <[moc.liamg] [ta] [selttu]> on Monday December 31, 2001 @08:50AM (#2767182) Homepage Journal
    Does the FCC have a problem with a person amplifying their wireless network without some sort of license? I'm totally ignorant on the legalities of this, but it seems like a really cool tip for free amplification!

    • Generally, the FCC only cares that you are within specified guidelines. I believe (and someone will correct me if I'm wrong here) that the 2.4GHz spectrum is limited in radiated power to 1mW. You can play all kinds of tricks with that by using highly directional antennae, and thus concentrating your 1mW power into one small cone. Or, you can spread the love around and try and radiate the 1mW spherically from a point source (hard to do).

      Most of the 802.11b devices don't radiate nearly as much as 1mW. This keeps them well below the FCC specs, and thus out of harm's way. Cranking your radiated power up to the full 1mW is perfectly fine. The caveat, of course, is that now you're sharing your traffic with much more of the planet.

    • Correction: (Score:5, Informative)

      by clark625 ( 308380 ) <[clark625] [at] [yahoo.com]> on Monday December 31, 2001 @09:07AM (#2767209) Homepage

      I goofed. The maximum radiated power is set at 1W. Not 1mW. Here's the FCC rules that apply, for those interested:



      Part 15.247 covers intentional Radiators in the ISM bands that are the frequencies 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz. Besides covering the modulation schemes this part also covers the various power restrictions that the FCC has for devices like 802.11b. The critical section is 15.247(b)(1) through 15.247(b)(3)(i) quoted below:

      "(b)The maximum peak output power of the intentional radiator shall not exceed the following:
      (1) For frequency hopping systems operating in the 2400-2483.5 MHz or 5725-5850 MHz band and for all direct sequence systems: 1 watt.

      (2) For frequency hopping systems operating in the 902-928 MHz band: 1 watt for systems employing at least 50 hopping channels; and, 0.25 watts for systems employing less than 50 hopping channels, but at least 25 hopping channels, as permitted under paragraph (a)(1)(i) of this section.

      (3) Except as shown in paragraphs (b)(3) (i), (ii) and (iii) of this section, if transmitting antennas of directional gain greater than 6 dBi are used the peak output power from the intentional radiator shall be reduced below the stated values in paragraphs (b)(1) or (b)(2) of this section, as appropriate, by the amount in dB that the directional gain of the antenna exceeds 6 dBi.

      (i) Systems operating in the 2400-2483.5 MHz band that are used exclusively for fixed, point-to-point operations may employ transmitting antennas with directional gain greater than 6 dBi provided the maximum peak output power of the intentional radiator is reduced by 1 dB for every 3 dB that the directional gain of the antenna exceeds 6 dBi."
    • Not only does the FCC care about the output power, they also care about the spectrum. In case of the 802.11b spectrum there is a main lobe, and smaller side lobes. The FCC regulates the ratio between the power on the main and side lobes. Increasing the power output will also increase the distortion levels, and the power output on the side lobes. This is bad because it interferes with adjacent channels. Manufacturers typically tune their equipment so that they are just within the FCC limits, so blindly increasing power output is not a good idea. The advantage may be smaller than expected too, because of the increased distortion in the signal.

  • Cable is out. (Score:4, Insightful)

    by ImaLamer ( 260199 ) <john.lamar@gmaiH ... minus herbivore> on Monday December 31, 2001 @08:54AM (#2767187) Homepage Journal
    Now that cable services are starting to fall and AOL begins to take over the cable market wireless points will be a huge innovation.

    But we are still waiting. Wireless is becoming the new thing, but communities need to respond. But buying these home [and business] wireless products hopefully this will fuel the boom.

    Now that my cable service is dropping me when using any P2P service and even newgroups [ahem] I've considered buying a bigger cable/pipe which I can do what I'd like with. Something with more freedom and the abilty to share the access with home I want.

    Now, my neighbors on both sides have internet access. One is my granparents whom use a $20 56K service and the others also use broadband [DSL].

    I'm completely capable of running mail services, hell even a proxy server. I can do all these things with redhat or debain out of the box. No matter what their needs are I can set up the system.

    Hopefully the wireless situation will become one where one could sell access to services. Whether they be a town, city or user group... let's hope wireless plays a big role in delivering a part of the 'last mile' solution.

    Although if wireless becomes too much of a 'hobby' then large scale networks may not be seen. Hope we see a balance.

    • Re:Cable is out. (Score:3, Interesting)

      by Lumpy ( 12016 )
      the problem is that your roof will look like a dish farm. 802.11 links require high gain antennas. the pringles can works but a primestar dish works 100times better. the best time to set up your links is mid summer. because 802.11 links will not shoot through trees with leaves. (nice how those water filled leaves absorb 90% of that RF energy you're beaming) getting to non-line of sight requires doubling the links to get around things... (A to B to C with B being a 486 with 2 wifi cards acting as a bridge) your house, if you are the hub will need a dish for every link.. (I gotta take pictures of my 60foot tower.. 3 primestar dishes on it, and 2 more going up this summer) now you can hub off of the other ends of the links, but only if you have control of the equipment at the other end and they dont care about 2-3 more dishes on their roof/tower (and I reccomend you demand towers at the other ends, makes it easier) get ready to have a new full time job if you do this. it will take most of your apare time, it will drain your pocket, and it will make you stop answering your phone. (calls from people when you have an outage, or it rains hard, or other problems... you just became an ISP and you'd be supries how people can bitch at you when their free internet goes down.
    • Unfortunately this may cause trouble with the ISP, as such usage may constitute theft of service (pretty much as with cable TV).
      • Not if I go huge.

        The problem is, I've been on the 'net for a while and it's become second hand. I don't abuse it, or even have an addiction.

        But I do realize the strength the internet has, compared to when I first got on. I can go watch "To Kill a Mockingbird" on the web. I can do so many things.

        There is great power there and I want to be able to use it. I want to be able to host a web page and share the usage. These lines do exist.

        No theft. I want highspeed! My point is, with wireless - a certain group of people could get access. I could share it with my neighbors who are close. No line of sight problems either. We can 'hide' the transmitters in the back of the yard.

        We are also lucky enough to have T1 lines in our area [within the mile].

        Simply, I want to have on demand access or even no frills access.

  • SNMP? (Score:5, Interesting)

    by omega9 ( 138280 ) on Monday December 31, 2001 @08:56AM (#2767191)
    From what i can tell, this doesn't have to be a Windows only hack. The piece of software [wi2600.org] that Xam states is only built for Win32 seems to be nothing more then an SNMP manager. Now, the Win32 tool might make it a bit easier, but you can hardly call it "requires a Windows box".

    • Re:SNMP? (Score:2, Informative)

      by T-Punkt ( 90023 )
      For *nix I suggest net-snmp (aka UCD-snmp):

      http://net-snmp.sourceforge.net/
      • Won't work as well as you might think. Atmel's SNMP agent makes gratuitous use of binary values for OCTET-STRING nodes, making it very difficult to set or read these nodes with standard SNMP tools.
    • You have to use the Windows manager because it's the only thing that knows what goes in the "data struct". A quick sniff of the SNMP traffic will fix that tho.

      Looking at the MIB, it looks like the application is likely putting the radio in "test mode" to set the output power. So the question becomes, does the new mega-power setting stay once the SNMP manager is killed or the AP power cycled?

  • The real trick (Score:5, Funny)

    by LtBurrito ( 267305 ) on Monday December 31, 2001 @08:59AM (#2767196)

    The real trick is to get your neighbor to turn up his power so you don't have to buy your own...

  • Wireless Phone interference (Score:3, Interesting)

    by joel8x ( 324102 ) on Monday December 31, 2001 @09:00AM (#2767200) Homepage
    Here's my question - I own a 2.4Ghz Seimens wireless phone and whenever I use that it cancels out my computer's wireless access! Does anyone know if this hack will affect this behavior (worse or better)? I would try it myself, but I use my iBook's Airport card for wireless access and can't run the program they use from my Mac, which would mean getting a PC wireless card to perform the hack.
    • I didn't realize that cordless phones actually could dump that much interference. Think of the possibilities! You could drive around a town with wireless access, and using your cordless phone, effectively 'Drive by DoS'. Better yet, (the signal probably wouldn't be strong enough, but) hook a nice sized battery to a cordless telephone base, turn on the reciever, and you just DoS'ed everyone on that tower! Even if Encryption gets better on wireless, its gonna need to move its ass off of an open frequency to be trusted by me. After all, a 15 year old can carry around a cordless phone, but I really doubt their gonna randomly choose my phoneline to cut. Advantage dialup. heheh =)

    • Re:Wireless Phone interference (Score:5, Interesting)

      by jandrese ( 485 ) <kensama@vt.edu> on Monday December 31, 2001 @09:16AM (#2767222) Homepage Journal
      Well, since your phone is probably some analog deal that just blasts out your voice, I'd say upping the power on the access point will just add a bit more noise to your conversation (and probably not help too much in keeping the signal strong when you pick up the phone, although it should help a little).

      A better hack might be to change the channel on your access point to something on the other end of the spectrum since you phone may not be taking up the entire band (unless it's a DSS phone). Or you might try moving your phone's base station and access point to opposite ends of the house.

      PS: Whoever modded this as a troll: what were you thinking?
      • I spoke with a Siemens engineer a while back about this. The phone tramples on everything from 2410 or so to 2495, IIRC. You can't turn specific hop channels off, either. :( So it's one or the other.

        (Anyone wanna buy a Gigaset? :)
    • I read about that a while back but I have never had that problem. And I have both the Linksys WAP and the Siemens phones. And it's not like they're far apart, I live in an apartment...

      I must be lucky I guess.

    • Re:Wireless Phone interference (Score:1, Informative)

      by Anonymous Coward
      Had the same problem, just make sure you seperate the Siemens base unit and the AP. That solved the problem for me!
    • yes, buy a new phone. the cheap 2.4Gig phones will interfere with wifi equipment. that the problem with buying cheap junk. Seimens cordless high end lives heppily with wifi as does the top of the line panasonic ($350.00USD) phone. look for the ones that advertise spread spectrum and will operate with other phones in the same house. These see a signal on a channel (and actually use the channels instead of broadcasting on the entier band at once) and hop around it.
      • nope have the $200 panasonic phone totally blasts my wireless if i'm more than 20ft away from it. (indoors ymmv) i'm going to get another ap and run ethernet into the living room (the only room far enough away that i loose connectivity.
    • Yeah I have one of the aforementioned $350 Panasonic 2.4 GHz phones, and it causes all sorts of problems. I had my AP on channel 1, and every time the phone rang, it'd drop all nextwork connections. I switched to channel 6 and that doesn't happen any more, but I still hear alot of noise on the phone.
      • We have a filter on our phone line that deals with interference from our DSL line (we have really old crappy wiring in our neighborhood). Works wonders for filtering out the noise from DSL, wonder if the same would alleviate some of the noise from the WiFi?

        ------------
    • If a cordless phone is killing your wireless connection the problem is usually that the phone is a frequency hopping spread spectrum device, which don't play well with 802.11b networks. Here's a snippit from a Cisco Wireless LAN FAQ about their Aironet line of products(they're the Cisco 802.11b APs and cards):
      ----
      Q. Would another vendor's frequency hopping (FH) equipment sitting next to our direct sequence (DS) equipment have any negative effect?

      A. Yes. By its very nature, an FH product hops across the entire band. It will therefore spend time encountering interference from our product and causing interference to our product. There is no way to control where an FH unit will hop. Blocking out the portion of the spectrum that the equipment uses would be a possible solution, but in the United States the FCC does not permit FH devices to limit their hop--they must hop across the whole band.

      Q. My WLAN system is seeing interference from a cordless phone. What can I do?

      A. Most cordless phones are FH devices, with the potential problems inherent to such products. See the answer above for more information.
      If the phone is a DS device and lands on exactly the same channel being used by the Cisco Aironet equipment, and if the phone is close to the equipment and you are using both simultaneously, then you will have problems. Try any or all of the following suggestions:

      Change the location of the Access Point and/or the base of the cordless phone.

      Switch to channel 1 on the Access Point. If that doesn't work, try channel 11.

      Use a remote antenna on the client card if it is a PCI- or ISA-based card and you have that option.

      Operate the phone with the antenna lowered, if that is an option.

      If all else fails, use a 900-MHz phone instead of a 2.4-GHz phone.


      ----

      If you'd like to read the whole faq check it out at http://www.cisco.com/warp/public/102/wlan/radio-fa q.html [cisco.com].

      • It sounds like dumb direct-sequence is the problem, not frequency-hopping. Frequency hopping sounds like the *solution* to 2.4Ghz problems since the devices can hop around to find open channels or less interference.

        It'd be nice if there had been an industry-wide bootup spec for looking to see if 2.4Ghz channels were in use and picking other channels if they were, or just make everything on 2.4ghz do FH SS.
        • There are pros and cons of both FH and DS spread spectrum. The general gist of it is that FH is cheaper and slower vs DS which is faster, more expensive, and sucks more juice. A quick Google search [google.com] returns some interesting pieces on the advantages/disantvantages of DS and FH spread spectrum including this article [wireless-nets.com] on wireless-nets.com.
    • 2.4Ghz Seimens wireless phone and whenever I use that it cancels out my computer's wireless access

      I have the same phone (three of them), and working 802.11 (with a Cisco 340, until it died, and then an Airport 'cause my office is close to the apple store...and it looks cool so my wife will let me put it in more "public" parts of hte house).

      Try changing the channel you broadcast on, and try the "reduce interference" setting on your iBook. Also if you don't have really good signal before using the phones try moving things around a bit.

      Does anyone know if this hack will affect this behavior (worse or better)?

      Since it boosts the base station, and not your laptop's output, it may not help (you might be able to see it, but it may not see you), also the boost looks kinda small.

      I would try it myself, but I use my iBook's Airport card for wireless access and can't run the program they use from my Mac, which would mean getting a PC wireless card to perform the hack.

      I don't think you need to try the hack from a wireless machine, just something with IP access to your WAP base station. Plus while the instructions for the hack are for using a PC tool, it is all done using SNMP, so you can grab some of the SNMP tools for Mac OSX and translate the instructions yourself. It might not buy you much range, but it would be a learning experience...

    • I have a high end panasonic phone that works fine along with my linksys wap11 (and also worked fine with my dlink ap1000)...the seimens should work too. They will interfere if you do not have your systems set to different sets of channels. I have my wap11 set to channel 9, or 11 (11 I found works better than 9 that I used at one time on the ap1000) and the panasonic you just turn on and watch your signal strenghth on a station, when it goes up when phone is on or off and phone is not staticy...you are golden. You see there are 11 channels in the us and 12 elsewhere, and 3 seperate groups of channels whose freq do not overlap.

      This only works with 2.5Ghz DSS phones and DSS (802.11b) equipment, you can forget it with a Freq Hopping (FH) phone or networking equipment like proxim sympony/rangelan...they will always conflict.
      • Correction sorry
        >and the panasonic you just turn on and watch >your signal strenghth on a station, when it goes >up when phone is on or off and phone is not >staticy...you are golden

        should have said:

        and the panasonic you just change channels using the channel button and watch your signal strenghth on a station, when it goes up when phone is on or off and phone is not staticy...you are golden

  • Better range increase.. (Score:5, Informative)

    by Spackler ( 223562 ) on Monday December 31, 2001 @09:14AM (#2767219) Journal
    The best way to increase the range of the linksys router is to not use a linksys card with it.

    Switching from the linksys card to an Orinoco more than tripled my range! It also made me realize that the linksys router signal _was_ hitting the street (I thought it wasn't reaching my couch with the old card), and enlightened me to "War driving". If your having range problems in your house, it is more likely your card.

  • Good for overcoming line losses (Score:5, Informative)

    by rcw-work ( 30090 ) on Monday December 31, 2001 @09:16AM (#2767223)
    At 2400mhz, 3-4db is equivalent to the loss in 45-60 feet of LMR-400 coax (or 12-16 ft of RG-58), according to this calculator [timesmicrowave.com].

    For those that would like to put an 802.11b antenna on their roof without worrying about weatherproofing their access point, this may be just the thing.

    • That's only half of the battle. By increasing your power you have overcome some of the transmit side loss in your coax, but done nothing about recieve loss. It actually doesn't make any sense for a traditional access point. The wireless client cards have worse antennas and so they are presenting a lower SNR (Signal to Noise Ratio) already. Now run the weak singal down coax and you loose 3dB which is the equivilent losing half the signal.

      Where this has real benefit is for bridging applications. I tried doing a 6 mile link with two WAP11's and 24dBi dishes, but it wouldn't work. The increased power on both ends might have been just enough.

      Still, it's a great hack (if it doesn't have unintended problems like overheating)!

  • This is an elementary SNMP set (Score:3, Informative)

    by arivanov ( 12034 ) on Monday December 31, 2001 @09:16AM (#2767224) Homepage
    Browse the MIB supplied by Linksys on their web site and do the same with scotty. No real rocket science here. It is as elementary as it can get.

    No need of the windows executable

    • Re:This is an elementary SNMP set (Score:1, Interesting)

      by Anonymous Coward
      The OID is enterprises.410.1.1.8.8.0 - but I can't quite figure out what the 14 char octet string should be.
      suggestion?

      if you want to set this via the CLI from a unix just run

      snmpset 192.168.1.250 private enterprises.410.1.1.8.8.0 s "some14charstring"

      the "some14charstring" is the important part
      -sv

      • Re:This is an elementary SNMP set (Score:1, Interesting)

        by Anonymous Coward
        According to the text page in the article the "some14charstring" is the power settings for the 14 channels. It should have a "c0bfbbbbb9b7b7b7b5b5b5b5b5b5" hex value encoded in it. Just change it to "8080...." encoded and you now have 100mW. (YMMV)
  • ...whether hacks like this are just plants by the parent companies sometimes.

    "So you tried to up the radio signal of your WAP11 by hacking it to boost the radio signal, and now it won't work? (Hey Bob, we got another one!) What, oh that was nothing sir. Sir, I'm sorry to say your warranty is void. But we do have a sale on the upgraded model right now..."
    • more likely I would think that if these so-called "plants" actually existed, they would be more likely to have purpose in garnering interest from the geek population in order to drive additional sales because "our product can be messed with to make it better without having to pay for incremental upgrades"...
      etcetera etcetera...

      I think these people just love doing what I love doing... taking things apart, putting them back together, and hopefully, not ending up with spare parts at the end. :)
    • Even if it doesn't fry it so the people have to buy another one, this information just got posted to a pretty major geek site. How many people will remember this when looking to purchase their wireless access point? You're sitting there looking at an SMC and a linksys, you remember this little piece of info, and you chose the linksys*. It's the geek value of "hacking" (even though you're actually more like a script kiddie unless you start trying something new with this). All in all, I'm going to support your idea of corporate planting of this type of information. Your ideas are intriguing and I wish to subscribe to your newsletter.

      *Actually, you still might buy the SMC, but because it has the seriel port and the print server built in.

      I've had it with this school, Skinner! Low test scores, class after class of ugly, ugly children...
      -- S.I. Chalmers
    • This is what Best Buy is for. The return clerks there think a "community string" is some sort of sex act. By the time you get around to explaining POSIX-compliant SNMP managers, they'll just issue the refund. Just make sure it's clean and all original packing is there.
    • No, I know Xam. He's not a corporate tool.

  • Rather Clever, Really... (Score:4, Insightful)

    by The Paradox ( 470614 ) on Monday December 31, 2001 @09:22AM (#2767232) Homepage Journal
    ...but, as always, your mileage may vary. A watt of power is, while not on class with many ham radios, even, still quite a bit.

    Essentially what I'm saying is, you turn up the power on this thing, you don't wanna wear it as a hat. Not that you wanted to do it before, but now you *really* don't want to.

    Remember, Linksys is not turning down the power just to spite the geeks out there. I imagine it could easily be a safety issue. Either that, or they had to do it to meet the FCC interference standards. If that's the case, you could have problems with devices that operate in that section of spectrum - I seem to remember something about wireless phone (NOT cellular, *wireless*, as in a base unit, then a detachable handset) working there.

    Also, just as a totally useless aside, looking at my handy-dandy (three or so years old) frequency chart I have here, I find it interesting that that portion of spectrum used to be for amateur radio operators. Co-located, perhaps, or did they just take it away from the amateurs altogether?

    • Re:Rather Clever, Really... (Score:1, Informative)

      by Anonymous Coward
      Several watts of effectively radiated RF at such a high frequency carries a serious risk of tissue damage through close-proximity RF burns. Nothing that would kill you but it'd hurt like a mofo, like most RF burns.

      The jury is still out on prolonged exposure, but I wouldn't want to be near one running even 1 watt for a long period of time.

    • Re:Rather Clever, Really... (Score:2, Funny)

      by Anonymous Coward
      >Essentially what I'm saying is, you turn up the power on this thing, you don't wanna wear it as a hat. Not that you wanted to do it before, but now you *really* don't want to.

      I can see it now. Admin puts a tweaked WAP11 on his desk and his coffee starts boiling in the cup.
    • Us hams have 902-928 Mhz and also the 2.4 Ghz bands. We don't really use them because they are cramped full public bands. One interesting thing is that we can transmit 1500 watts on them, and we have a higher assignment as a licensed operator. In theory we could blast 1500 watts on one of those public bands, and totally kill tons of public equipment in a large area, and it would be up to the unlicensed operators to work around us.

      In practice, the FCC would probably view that as intentional interference, which is a no-no even if you are licensed for a band. Of course, when sounds like a clear frequency on one of those bands is no doubt well occupied by many signals you can't hear, since they are all so low power. So one could always claim that they were on an open frequency, from what they could hear. :)

      Anyway, so yeah, we can, no we usually don't.

      Besides, it would be impossible to even monitor the 902-928 without breaking Newt's law against listening to phone calls.
    • Also, just as a totally useless aside, looking at my handy-dandy (three or so years old) frequency chart I have here, I find it interesting that that portion of spectrum used to be for amateur radio operators. Co-located, perhaps, or did they just take it away from the amateurs altogether?

      It is still an amateur allocation. I believe part 15 devices (such as wap and cordless phones) are a tertiary allocation.

      That band is used by amateurs. As a matter of fact, there was a recent incident involving an apartment building wired for 802.11 that was interfering with some amatuer use of the band. Another reasonb why you don't want to increase your output power without reason. All of this stuff can work together just fine as long as people realize that if 10mW does the job, you don't need to be running 1W of output power.

      Excerpt from the ARRL Letter, Volume 20 Number 7 [arrl.org]

      FCC QUERIES WIRELESS 'NET PROVIDER ABOUT INTERFERENCE TO HAMS

      The FCC has asked a wireless Internet system provider what it intends to do
      to eliminate interference to Amateur Radio operations in the Dallas, Texas
      area. The FCC wrote Darwin Networks Inc on February 8, 2001, regarding
      complaints of harmful interference to Amateur TV on 2.4 GHz that's said to
      be a result of the company's deployment of Part 15 devices in an apartment
      complex.
  • I wonder if there are similar registers for the
    pcmcia cards, such at the Wavelan/lucent/orinoco
    cards, or the prism II based cards? Open source
    drivers would make turning up the heat on these
    things easier and might help make some links more
    stable.
    • For many of the pcmcia cards (probably not the cheap ones), a client utility is usually included that allow you to change the output levels. I actually turn mine down at work as I have an AP at my desk and I'd like to keep my hair. ;0) Really though, I'm only using it for testing so 1mW on both ends works just fine and reduces the chance of an attack (both internal and external, i work at a big company) since the range is reduced.
      • I have two d-link DWL650s at home, one on a Win98 laptop and another on a Win2K. With both the laptops sitting side-by-side, about 30 feet from the Linksys WAP, the Win98 laptop had a strong signal (>80%) whereas the Win2k indicated a poor signal ( 0%). And yes, I did interchange the cards between the laptops.

        Leads me to believe there is some software setting in the device driver.
      • I guess my point was WHICH registers are set and
        how can I tweak the FreeBSD wi driver to have an
        ioctl to allow me to set them for orinoco cards.

        I have a wireless link that is based on FreeBSD boxes and a few extra db is all I need to overcome
        the leaves in the summer, and snow storms in the
        winter.

        Since I control both ends, I can boost the power
        symetrically and still be within the FCC guidelines for radiated power (I'm about 10dBi
        under the limit if I read the power meter I have
        correctly). Yes, I've taken the gain of my
        antennas into account. No, I can't buy larger
        antennas because 24dBi is the largest that will
        mount on my roof.

        So I'm left with getting an amp, or having the
        cards put out more power. I'd like to avoid an
        amp...

  • bad engineering practice (Score:5, Informative)

    by lophophore ( 4087 ) on Monday December 31, 2001 @09:31AM (#2767251) Homepage
    Since the 802.11b communications link is two-way, increasing the transmit power of only one end (the access point) is not going to buy you a whole lot. To increase the range, you need to either increase the effective power on both ends, or, more simply, put the access point up higher.

    A higher gain antenna on the access point would help with both transmit and receive, and this is another option, however, I think that this might be illegal in the US.

    Also, it is useful to recall that microwave ovens operate on 2400 MHz because this is the most efficient frequency for heating water. One watt is enough to cause some RF heating and potentially be hazardous to you health. Don't look at the business end of that yagi!

    • Since the 802.11b communications link is two-way, increasing the transmit power of only one end (the access point) is not going to buy you a whole lot

      Not necessarily true. If most of the traffic is coming from the AP (a typical case since the AP is usually connected to the servers using a wired network), increasing the power on the AP may allow it to use a higher rate (802.11b has rates between 1 and 11 Mbps). The client card could still use a lower rate for the acknowledgements.

      This wouldn't necessary increase your range, but it can certainly increase your throughput.
      • case in point: I added an external Base antenna to my Aironet 900mhz 'base' (ie, an isa card in a software router). My range went from two houses down my street (300ft) to close to 1000ft.
        The antenna is in roughtly the same space the stock rubber ducky was, but vastly improved my ability to surf while walking down the street.
        • and you need to surf while walking down the street because?????? This is just assanign. If you don't really need the range, don't do this hack. I can walk all over my house and even into my driveway ( i do work on my truck and look things up when i do it) and I have had no problems. Your neighbors are going to start to complain about cordless phone usage and what not at some point.

          Again this is a neat hack. If you do need the range and it isn't going to interfere with anyone elses use of this band then by all means. But if it does interfere and/or you don't need the range, don't do it. If there is a HAM operator in your area, sooner or later you will be found, cause they use part of that band as well.

          not to mention if your range is extended that then the 14 year old down the street can then hack your network from the privacy of their house instead of having to sit outside yours. have fun.
    • There are certainly risks associated with doing this hack. First thing is that the human body is most sensative to RF resonating between 30 and 3100 Mhz. Since this falls in that range, sitting next to that access point is probably not a good idea. And since sufficient studies have not been done to test the long term effects of RF on the human body, I wouldn't do it. Heck I keep my access point no less that 4 feet from me and I have the USB tranciever to keep it minimum 4 feet from me as well. And though 1 watt of power isn't a whole lot, when it is sitting next to you and is on all the time is probably not a good idea.

    • Also, it is useful to recall that microwave ovens operate on 2400 MHz because this is the most efficient frequency for heating water. One watt is enough to cause some RF heating and potentially be hazardous to you health. Don't look at the business end of that yagi!

      While I don't condone pointing a highly-directional antenna through you to test, 1W is nowhere near the power of even the smallest microwave ovens. I believe my old beastor is a 750W microwave, and the little'uns are 100-150W.

      Aside: Having 1W at the output of the RF amp is not the same as what's coming out of that yagi; highly directional antennas focus that 1W into something (potentially) much, much higher. Is that 1W ERP or 1W at the amp? Remember that LED-communications system on /. a week or so ago? by using fresnel lenses the effective optical power was 10kW from a 650mW LED! Directional antennas can do some pretty serious amplification!

    • If you had two access points talking to each other via special external antennas, then extra power would be a good thing, assuming you are under the FCC limits.

      100mW is still well below the threshold of RF heating. I'd be surprised if even standing in
      the beem of the 24dBi dish antennas would be harmful. I know several people that have done so with no ill effects.

      But I guess that experience is no substitute for good theory :-)

  • Other 802.11b improvements (Score:4, Interesting)

    by Arkham ( 10779 ) on Monday December 31, 2001 @09:38AM (#2767264)
    There are two worthwhile articles over at Macintouch [macintouch.com] about 802.11b (AirPort in the mac world). I thought they might be interesting to people looking to improve their wireless LAN performance or range.

    Adding WaveLAN Extender - This article [macintouch.com] discusses adding various antennae to base stations to improve their range.

    Extending TheAirPort's Range - This article [macintouch.com] discusses some more radical procedures, including some neat stuff with Directional Antennae which allow 802.11b to work as far away as a 57 Kilometers. They also discuss various antennae to add to laptops in order to improve their range.

  • Fun with Wap11 (Score:4, Interesting)

    by bwags ( 534113 ) on Monday December 31, 2001 @09:53AM (#2767287)
    Funny, I just worked on boosting my power this weekend before this post. It works like a champ! This info came out earlier this fall but it is nice to see it all written up in such a nice manner. I have a whole bunch of printouts describing all this stuff and I somehow pieced it all togethter. I have a couple of notes of interest pertaining to this stuff:


    First, I never did upgrade the firmware to 1.4g5 or 1.4g7, I am running 1.4H3. I guess I should upgrade, but that would require me to actually get the AP next to my PC for the USB connection. The upgrade seems to work OK without the latest rev as long as you can connect via snmp. I think I must have the 1.0 hardware since I got this thing Jan 2001.


    Second, I think you can also turn off the SSID on your WAP using these utilities. I have not tried this but perhaps it could help if you are paranoid...


    Finally, The main reason I worked on trying to fugure this out is because my wireless network was running very slow. I finally figured out the reason was the wpc11 linksys pcmcia card that I have. If you have one of these cards make sure to DISABLE the PowerSaveMode in your network configuration (in Windows). Your network will now run significantly faster (500K/sec instead of 50K/Sec in my case). Also when exploring in windows use mapped drives instead of unc names. This seems to also help.


    Hope that helps, BRian

    • Finally, The main reason I worked on trying to fugure this out is because my wireless network was running very slow.

      Well, at least that's all the problem you had. I put the 1.4f firmware into my WAP11 when I bought it, and the SSID would keep dropping out after a few hours, and come back after power-cycling the unit. Finally, when I demanded a RMA, they send me some newer firmware which fixed the problem.

      In the meantime I found a good deal on a v1 AirPort ($200 at Fry's that weekend) so now I have them set up on opposite ends of the house for maximum coverage. Add a DHCP server which knows both my laptop's Ethernet and AirPort MAC addresses, and OS X, which automatically switches over when I plug/unplug the Ethernet, and I've got some sweet networking.

      By the way, the hardware in this unit is OEM stuff from Atmel that is also in access points sold by NetGear, AddTron, and others. But LinkSys's version is the best because it has the removable antennas, and they have newer versions of the software available for download. (The v1.3 shipping with all of these brands, even Linksys, is supposed to have some SNMP security problems.)

      Second, I think you can also turn off the SSID on your WAP using these utilities. I have not tried this but perhaps it could help if you are paranoid.

      I'm just the opposite. I put my e-mail address as the SSID, since this is my home network. Except that Apple's software doesn't like the "@" character in an SSID. I don't have too much to be paranoid about, what with all the WEP-free DHCP-serving access points in my neighborhood being much jucier targets for drive-by spamming.

  • ...and as your device is running too muich power throough the finals and it smokes, much like your overclocked AMD, you'll realize that you should have cracked open the case and put a fan on them.
  • Why not just use a card? They are much cheaper.

    Get an Intersil Prism2 card and use the Prism 2 AP module to turn your Linux box into an AP.
    • Because AP's are stand alone devices. Oh and if you look you can find the for the same price as a wifi card.

      I bought 2 sohoware AP's for $75.00 each at best buy. they're on clearance and work great!

      downside of the soho ware line. you cant encrypt as it's 24bit only (big deal, I dont encrypt at all, I use my firewall to hand out authentication) and requires a soho card and windows to configure the accesspoint (no config needed tho. open box, turn it on.)
    • An AP is 1/10th the size of a Linuxbox and 1/100th the hassle.

    • Why not just use a card? They are much cheaper.


      Well, a card is cheaper, but a card, and an adapter and a computer isn't. The access points
      are in the $100 range, and the card takes up at least $75 of that. It takes a lot of scrounging to put together a machine with ethernet for $25.

      And the access points are a lot more convenient to reset.

      And the Linux AP code still has some issues, so
      it needs kicking more often than the access points
      do (at least that's what people that have used
      both tellme, I don't run the Linux AP code).

      And an access point takes up less power than the
      $25 486 DX + ethernet card + monitor (well, if you
      are lucky, you can run serial) that you were able
      to scrounge.

  • MIB hackery (Score:5, Interesting)

    by danish ( 60748 ) <danish@debian.org> on Monday December 31, 2001 @10:32AM (#2767384) Homepage
    After installing the snmp utils (apt-get install snmp) and doing some minor surgery to the MIB [linksys.com] so it would parse correctly, I think I've found the element to modify:

    enterprises.atmel.atmelmib.atmelSys.TestModeSettin gsGRP.TestModeRadioConfiguration.0 = Hex: CA CA CA CA CA CA C9 C9 C9 C9 C9 C9 C9 C9

    Although not in the same configuration as the article describes, this may be due to the fact that I've never upgraded the firmware on the access point I snmpwalk'd this from. Perhaps I should get busy on that....

    Any of you people out there with an upgraded firmware, you should try snmpset under Linux or your UNIX of choice and see what kind of results you get... extra points for verifying the change with the Windows stuff in the article.

    Numerically, snmptranslate says that the correct field is .1.3.6.1.4.1.410.1.1.8.8.0, assuming I'm using it right (I called it with the commandline snmptranslate -m +ATMEL-MIB -IR enterprises.atmel.atmelmib.atmelSys.TestModeSettin gsGRP.TestModeRadioConfiguration.0.)

  • In the article it states: "this will ammount to 3 to 4 db gain in power, which isn't all that much, but heck, it's free".

    3dB will result in a signal that is 2 times as strong. So, yes, it is quite a bit more.

    When refering to decibels, every 3dB means 2X the power. Just thought I would point that out.
  • Does anyone know if the WAP11 is the only Linksys AP this works on? I use the Router/AP combo and don't seem to be able to make it work.
  • Everyone in wireless knows that the 2.4GHz is already more than a little crowded, having to share the air with cordless phones, garage door openers, etc. etc... Even though this is a very cool hack, if you don't theed the extra range I would ask that after you have had your fun that you turn it back down a bit. When I first got into wireless it was all about how far I could throw a signal - but I realize that as things get more crowded out there, keeping my signal strength to the minimum level that will get my particular need taken care of is the neighborly thing to do. When I finally get my hands on some 802.11g gear that operates over the same 2.4GHz spectrum I want there to be some spectrum left to use! ;-)
    --
    The Sphere Guerilla Net [photonsphere.com]
  • Generally, with a directional antenna at those freq's you could get 10 to 20dB of gain, or more. Now take one watt (or whatever) and multiply it by 10 or 13. That's your ERP or effective radiated power. If your feedline isn't too long and its high quality microwave coax, these calculations should hold up pretty well. It you have to run 50 or 100 feet, you're hosed, as only something like Andrew's Heliax will have the small enough loss/ft at these frequencies.
  • ...making the antenna higher.

    Don't try to mount the antenna remotely; the loss in the transmission line would overrid the gain.

    Instead, run ethernet and power to the highest point in your house and put your linksys there.

    This method is safe, legal, and it WORKS.

  • the power boost upgrade worked like a *charm* --
    many thanks to timothy and slashdot for the posting!!

    the linksys upgrade to 1.4h3 also worked like a
    charm, and fixed all sorts of problems I was
    experiencing trying to config the thing.
    (client was my one win2k box)

    I too have experienced crappy reception with their
    PCMCIA cards... not sure why.

  • lower power levels=better security, oerhaps? (Score:1, Interesting)

    by Anonymous Coward
    Note that not only can you -increase- the power, you can decrease it too! "Why on earth would you want to do that?!?!" you say.

    Just think...the AP that was suddenly accessible from the road is barely accessible from the front lawn. Maybe you use your AP within a pretty close range etc...lower power levels would be just fine.

    The linksys also allows you very fine-grained control over supported data rates etc; experiment with, say, turning off everything except 11mbps and tweaking the power level down one notch up from where you start to see packet loss etc. Tada, maybe now your network that was visible from the street is only visible from the yard or front door. Granted, some antenna-kiddie(ooo, I coined a new term!) is still going to find the AP when he points a directional your way, but oh well...at least it'll maybe discourage the average moron who recides to go driving with his laptop.

    Not to mention, if you're nervous about scrambled brain, having the AP at a lower power level might make you feel better, although the card is what is closest to you...

  • WARNING: I tried this hack... (Score:5, Funny)

    by dstone ( 191334 ) on Monday December 31, 2001 @01:12PM (#2767999) Homepage
    ...and my Pringles can burst into flames.
  • Of course I'm still wondering why 802.11 didn't fly on AO-40. I'm sure some FCC regs got in the way of that one.. that sure would have been a much-needed leg up for amateur radio.

  • What about those of us that have the BEFW11S4, Linksys' Wireless+Router+4-port Switch device? I don't believe these guys have SNMP capability. There might be something in the firmware that could be tweaked. It would take some poking with a hex editor, I suppose... Anyone hacked on this little Linky?
  • One of the first replies mentions 1W being the maximum power allowed in the band by the FCC. The way it is worded appears to have led a number of people to believe that this is what the mod allows the access point to do. Having read the link, it looks like the mod allows for up to 100mW of power. Aren't there 100mW cards and access points everywhere? Maybe I'm mistaken but this only looks to be of value if the hardware in question can be found for dirt cheap... Even then you wouldn't be getting extraordinary performance; just typical performance at a good price.
  • As some posters have reported, it is possible to increase usable range by boosting the output power of the Linksys box. However, you should keep in mind that the wireless link between your client device and the AP is limited by the weaker direction. Say, for instance that you have a 1 watt transmitter in your (industrial-strength) AP, but only a 10 milliwatt transmitter in your client (handheld PDA) device. All other things being equal, your 100X greater AP transmit power will be wasted, because the AP will not be able to hear your puny 10 mW handheld device more than 30 feet away...

    The formal term for the analysis of effective range between two stations is LINK BUDGET. This is influenced by the following:

    a) Raw transmitter power
    b) Receiver sensitivity
    c) Feed losses (e.g. long coax runs)
    d) Antenna "gain"

    All of these must be factored in to determine the effect on range which may be obtained by altering ANY of them.

    The key here is that since both the AP *AND* the client device must be "hearable" by each other, boosting transmitter power on one end and changing nothing else has limited (if any) benefit.

    In practice, you may be able to get an appreciable improvement in usable range by boosting the AP's transmitter power, simply because if you're using the wireless link for web surfing, you are receiving (on your client device) much more often than you are transmitting. In actuality, your client device may be re-transmitting those HTTP "GET" messages a number of times before it is heard by the AP, but the effect is inconsequential when the bulk of the traffic is being received by the client device.

    Turn it around and try making your laptop a web server and see how "symmetrical" the performance turns out to be...
  • Could someone with one of these access points please read the FCC ID off the sticker on the back and post it here.

    I want to look up what transmit power the device is certified for. From that I can answer everyone's questions about whether the FCC cares about this particular hack.

  • Man after a whole afternoon of screwing with a WAP11 and a BEFW11s4 (router with 802.11b and 4 port switch) trying to get the WAP to connect in client mode to a BEFW11S4 I never could get it and I don't know when linksys is gonna fix it.

    Thankfully Slashdot came to the resuce with something fun for me to try, anybody out there had any luck making a BEFW11S4 more capable? They kinda suck compared to a WAP11 since the WAP11 can be an AP, Client, or Bridge. I've read about using TFTP to download WAP11 firmware onto a BEFW11S4 but I'm a little hesitant... Any advice?

  • Thanks to whoever posted the FCC ID. The ID is O7JGL2411AP (note first character is letter O, which is not what they posted). The post didn't say which of the OEM brands this corresponds to, but I expect all are the same.

    This device is certified for only 82 mW of output power. 100 mW is a violation.

    So indeed, the FCC will be upset by the hack. In this case it is the license grantee who will get in trouble (global sun technology inc, jung li city, Taiwan) for building a device that users can take out of compliance.

    View the FCC license [fcc.gov] for the device if you are interested.
  • It'd be neat if the author of "fun_with_the_wap11.txt" could find out just WHAT part of the h/w was being controlled by the power parameter, ie. what amplifiers and/or attenuators.

    Since the 802.11b radios are TRANSmitting devices - not just emitting or receiving - we can hope the parameter being mucked with controls the receiver's IF amplifier as well as the emitter amplifier.

    In that case, the outbound pulses are stronger, AND the weak-kneed inbound pulses are given a kick in the pants before being passed along to the analog and digital processing stages. This increases the odds for analog signal detection and digital network layer traffic.

    Keep in mind that cranking an amp also increases the heat generated inside a cramped pcmcia card, translating into either shorter life or the addition of heat sinks and fans. Those who are serious about longer range go with the two way amps from Hyperlink, et al.
  • Does anyone know if this hack would work on a d-link WAP? As far as I know, it uses Atmel...

  • So... (Score:2, Funny)

    by Stone Rhino ( 532581 )
    How many of these will I need to replace my microwave?

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