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Wireless Congestion 130

AllMightyPaul writes "An article on CNN describes the congestion experienced by many users of wireless networks as more and more people begin to use them at home and at work. The unregulated frequencies between 902 and 928, where most Wi-Fi devices operate, sees a lot of traffic, apparently."
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Wireless Congestion

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  • Seems to me that an article about RF congestion was posted earlier today...
  • by Jerp ( 135831 ) on Sunday June 02, 2002 @07:32PM (#3628135)
    According to the article, WiFi uses the 2.4GHz range ("2.4 to 2.483.5 gigahertz")...
    • by aqua ( 3874 )
      I might be mistaken about the significance of it, but while 802.11b at least is capable of a dozen or so channels, most 802.11 networks are using one of only three (1, 6, 11; 2.412, 2.437 and 2.462GHz respectively) of them. So there might be some overuse there.

      It'd be interesting to see some mobile spectrum analysis of frequency usage over geographic areas, to see if that plans out -- map spectrum emissions and see if there's an aberrant concentration in spots. Might not be terrifically useful, but cool data.

      Aside from broad deployment of spread spectrum for future RF-emitting gadgets (the ones not using it already), it'd be helpful if devices like 802.11b access points could indicate when they're having interference problems, so as to distinguish these problems from those of topography, incorrectly installed antennas, hordes of evil lurking microwave ovens, etc.

      • That's because adjacent channels interfere with each other. They are not completely isolated channels as would seem logical.

        The three in common use you will notice are the lowest, middlemost, and highest channels. Lots of space in betwen.

        Devices DO indicate if they are having problems.. they give you indications of signal strength.
        • That's because adjacent channels interfere with each other. They are not completely isolated channels as would seem logical.

          The three in common use you will notice are the lowest, middlemost, and highest channels. Lots of space in betwen.

          Hmm, okay, that makes sense. However, as transmitter density increases, that concentration ceases to be ideal.

          Devices DO indicate if they are having problems.. they give you indications of signal strength.

          Insufficient specificity. It doesn't discriminate between poor signal propagation and emissive noise on the channel, which are cured in different ways.

          Another approach would be for devices to make channel recommendations by checking each for round-trip signal strength and passively-sampled noise on the channel. Or simply to pick one automatically.

      • That's because companies (even the vendors of the hardware) don't know what they are doing when installing a 802.11b network. The "trick" is to think of it as a 3D Star Trek type chess game. You CAN use adjacent channels, just not in AP's that are physically, or more importantly measured in "RF-distance", close to each other. Most installers are not intelligent enough to think in 3 dimensions, let alone the 4, yes 4, required for a proper facilities analysis. And the 4th would be... the physical makeup of the facility. Two AP's placed on opposite sides of a sheetrock wall are "closer" than two AP's that are placed on opposite sides of a concrete wall, which in turn are "closer" than two AP's placed on opposite sides of radiation shielded wall around a radiology department in a hospital. All WAY too much to think about for the average RF installer, and THAT's why they recommend only using 1, 6, and 11.
    • Like all resources, it will be offered at little or no cost until it becomes sufficiently limited, at which point the cost to utilize the resource will increase, and provision of the service will become proffitable, so we will see the end of community wireless networks, and the re-emergence of for-proffit networks, where access is restricted and the frequencies used will only be available to subscribers.

    • ya, so does your microwave, your garage door opener, bluetooth, maybe one of your portable phones, and about 100 other things. You just gotta stay one steap ahead of the game, 802.11a, that works on the 5ghz garbage range. That is still pretty clean. Linksys just made a wireless networking product that works on 5ghz and gets 75mb/s... It is backward compatible with the 802.11a standard.

      I don't remember the name but there was a big hacker conference (2600 type stuff) over in the Netherlands that had soo many guys using wifi that they maxed out the spectrum. They also raised a weather balloon with ethernet attached and did a bunch of other wierd stuff.

      • The problem is that the 75Mb/s stuff takes 2 channells and therefore adds to the problem. Not to mention that their receivers are so crappy that it can only do the full rate at 10m or less.
  • Sounds like a bunch of FUD. Yes, there were some occasional problems. How about the incredible convenience this technology enabled, and the many people and organizations that were able to benefit? The article sounds like it was written by one of those negative people that always stand on the sidelines and comment about why things won't work, without trying to help. Pfft.
    • Dude, if it isn't already a problem (which would suprise me), then it soon will be.

      You can't deny the fact that with the limited frequency ranges and tons of adopting users, we will quickly approach critical mass. I would imagine that in some areas, where wireless technologies cohabitate in high concentrations, critical mass is already in the foreseeable future.

      I often wonder how we can achieve this utopian wireless world (a Net connection in every citizen's pocket) with the overbearing FCC regulations we have to exist under right now.
      • Re:Sour grapes (Score:2, Interesting)

        I'm not worried. I am posting this comment from a laptop with 802.11b, while a 1.3KW microwave oven 10 feet away is cooking my dinner at full power. At the same time, my laptop is playing MP3s in the most gluttonous manner: using a remote esd connection to a box hooked up to a stereo, without any problems.

        Now how am I to take seriously the rest of the points that the article makes, if even the one most obvious and easy to verify is wrong in this one instance?

      • I often wonder how we can achieve this utopian wireless world (a Net connection in every citizen's pocket) with the overbearing FCC regulations we have to exist under right now.

        Now is a good time for something to be done about that. There is an ITU plenary session in a few months. So now would be a good time to lobby the (national?) delegates to get wireless LAN and other portable communications official recognised and given rights to use spectrum space (rather than being permitted to use it subject to accepting interference from, and prohibition of causeing interference to, other services.)

    • FUD? No problem exists?

      Tell that to the students at the college I work at (as telco admin). None of them want to be limited to their room by a wire for phone calls, so they all bring either a 900 MHZ or 2.4 GHZ phone (the cheaper, the better, so most are 900 MHZ). Now, at 120 students per hall, with 3 halls in close proximity to each other, there's a hell of a lot of students complaining to us that they're hearing other people's calls from time to time, and they want us to fix it.

      I can't. Not much else I can say except to try getting a newer 2.4 GHZ phone to try to transfer some of the load from the 900 MHZ channels, or else use the landline. Yes, a cordless phone is a great benefit.

      But the issue at hand is far from "FUD" and "No problem exists".
      • Why are they not using "standard" (GSM) digital cell phones? With these there is no chance of hearing other people's calls. If the user density is that high, then the phone network should install a cell basestation to cover the halls.
        • Nope, these aren't cell phones. Your standard Wal-Mart $35 900 MHZ landline phone (with a base receiver plugged into a landline). These are the ones you can term as a "cordless" phone.

          Now as for cell phones, those are in use too, but the only problem with that is kinda weak signals. We've talked to the various cell providers time and again (this is US, so there's abut 5 major providers using as many different types of networks), but nothing has come out of it.

          BTW, the most popular cell phone on campus now seems to be Nextel with the Direct Connect feature (everytime I hear someone's chirp, I reach for mine.) Must have something to do with how colege students love to use chatrooms and instant messenger.

          Now if they'd only make other colege activities portable...
  • Hmmm, these problems all relate to 802.llb... 802.11a isn't as widespread yet, but it is faster... any idea if it is also less prone to these collisions? If so, maybe it would have better effectiveness in adoption.
    • The problem for adoption is the price... I'm not going to buy a 600 dollor access point to have 802.11a in my home when i can buy a 150 buck access point for 802.11b.
    • I would imagine (though I have no evidence) that if it is faster yet people use it the same, there would be room for more data to be transferred without collisions. Each packet will take up a smaller timeslice, so more packets can be transferred without interference. Also, the article says the 802.11a devices automatically adjust their transmit power, which should lower the amount of interference quite significantly.
      • Collisions will happen just the same. You can pack more data in, yes, but the time between a node beginning to transmit and the other nodes seeing that it starts to transmit will be exactly the same. Thank Einstein for that.

    • Of course it's prone to collisions. The protocol is the same, the frequency is just different.

      It's not fundamentally any different.

      It is no more or less prone to interference than 802.11b.

      It may be that there IS less interference because it's a relatively new band, but it's no less prone to it.

      • Actually, the technology is very different. Yes, it will equal the same in the end, eventully it will get crowded and cause collisions, but it will happen less quickly than it did with 802.11b.

        802.11a uses a technology called Orthogonal Frequency Division Multiplexing (OFDM), which significantly increases channel availability, mostly due to its ability to split them into seperate, more unique channels. It manages to create more independant channels by combining low speed subcarriers into a larger high-speed channel.

        Check out this good article about this:
        Proxim Article on OFDM and 802.11a [proxim.com]
    • Re:802.11a fix? (Score:2, Informative)

      by bridges ( 101722 )
      802.11a, which operates in the 5GHz range, is not a significantly different meda access protocol than the one used in 2.5GHz 802.11b. If there are enough people moving into the 5GHz range, then collisions and such are inevitable there. 5GHz is still preferable to 2.5GHz, however. One reason the 2.5GHz range was given to unlicensed spread-spectrum transmitters because it's so noisy to begin with - there are a lot of devices that radiate in the 2.5 range that don't follow *any* network media access protocol like CSMA/CA, like a microwave oven. At least when two access points fight over a single frequency, they might be able to do so in a structured way that's relatively fair to each transmitter. Microwaves, however, don't "play nice." :)

      Apparently the 5GHz band is cleaner than the 2.5GHz band, so at least the background noise will be less, and hopefully the transmitters in the range will all use a common media access protocol so that the interference that is there will be more cooperative and not just straight radio interference. One possible solution to this problem might be a configuration protocol is created to allow different access points in the area to automatically negotiate which channels they will use, so there isn't even the collisions that happen when to WiFi devices share the same channel. I've never heard of anything like this before, however.

      -Patrick Bridges
      • Such a configuration protocol would require authenticating access points across organizational boundaries to avoid Denial of Service attacks or one wireless user to maliciously exploit the protocol to gain more bandwidth over neighboring users.
      • If you don't think OFDM is significantly different from DSSS then you need to sit down and talk to a wireless engineer. Second, microwave that leaks enough power to do anything to your wirless network should be replaced as it is radiating too much power to be healthy for YOU. Finally, until the cost of the MAC comes down I don't expect to see too many portable phones on the 5Ghz ISM band.
        • I'd agree. He makes it sound so convincing, but he really doesn't know what he's talking about. Probably doesn't even know what DSSS and OFDM stand for.

          Perhaps if he read

          IEEE 802.11, 1999 Edition [ieee.org]

          IEEE 802.11a-1999 [ieee.org]

          IEEE 802.11b-1999 [ieee.org]

          IEEE 802.11d-2001 [ieee.org]

          he would be more informed...

          • Uh, you'll note I was referring to the media access methods, not the spread spectrum technologies. 802.11a is still a shared-media system, so you're going to have collisions and such no matter what spread-spectrum technology you use. You're right that I don't know much about ODFM, though of course I do know what DSSS is.
    • 802.11a will have an easier time of it than 802.11b will, as it has many more unique frequencies. In 802.11b, the unique ones are 1, 6 and 11, but in 802.11a there are many more channels, eight channels. This means there should be less collisions than on 802.11b as there is much more spectrum to play with.
    • The 5Ghz band is mot presently used by older technologies. Because of it's higher frequency, it is more subject to signal attenuation and multipath interference in typical venues, making it a shorter range technology. To overcome these limitations, a different signal modulation technique is used (OFDM). This is the same modulation used by the new 802.11g equipment that operates in the 2.4 GHz band. This technique is more fundamentally robust and use of a single species of device (sans the $79 microwave ovens and frequency hopping phones) is likely to reduce "unexpected" interference. Eventually, though, "cell" oriented technology will be rquired to control interference and maintain optimal bandwidth.
  • Few things. (Score:5, Informative)

    by mindstrm ( 20013 ) on Sunday June 02, 2002 @07:53PM (#3628198)
    1) so-called Wi-Fi, usually 802.11b, uses the 2.4Ghz ism band, not the 900Mhz one. Most wifi is therefore NOT 900Mhz.

    2) Of course it's going to be congested! There is a REASON the 2.4Ghz band is where it is. It's dirty, and unlicensed. It was designated in the first place as an ISM band because it's dirty; it's not as commercially attractive as other bands in the same area. The fcc regulations REQUIRE you to accept interference from other devices.
    • I thought the reason it was designated as ISM is because it contains the frequency which excites water molecules - therefore Microwave ovens are constrained to use this because of physics not regulation.
      • what does the shared Industrial Scientific and Medical (ISM) spectrum have to do with the frequency which excites water?
      • Common misconception. There's nothing magical going on between water and 2.4GHz - water molecules happen to absorb a good bit of energy at that frequency that gets translated into heat, and it happens to be in an ISM band.

        If water was resonant at 2.4GHz, you would boil all of the water out of your food within the first 10 seconds or so of cooking - not the desired result. You want the water to absorb the energy slowly enough to give the heat time to conduct into the rest of the food. See this [eskimo.com] and this [winstonbrill.com] article.

  • Ehh? (Score:5, Informative)

    by EchoMirage ( 29419 ) on Sunday June 02, 2002 @07:54PM (#3628201)
    From the article:
    Headsets and other gadgets using the Bluetooth standard, newer cordless phones and microwave-powered, energy-saving light bulbs share the 2.4 to 2.483.5 gigahertz frequency range used by Wi-Fi. Household microwave ovens use radio waves in that range to heat leftovers.

    802.11b Wi-Fi devices occupy the 2.4 GHz spectrum, not the 900 MHz spectrum as erroneously stated by the article submitter.

    802.11a, by comparison, uses the mostly-unoccupied 5 GHz spectrum, making it less prone to interference. It also boasts about 5x the theoretical bandwidth of 802.11b.

    Furthermore, there are additional 802.11 hybrids that occupy different frequencies and offer different bandwidths.
    • Yes, and how long will it be until the 5GHz range is crowded too? It's only a matter of time.
      • The thing about the 5GHz range is that the signals won't travel nearly as far, either. So, while it might be clear of other devices trying to use that range, you pay for it in signal coverage. But until the price of chips that transmit on those frequencies comes down significantly, the 5GHz range will continue to be quite vacant.
    • The article does NOT state that Wi-Fi devices are in the 900 Mhz range - it merely talks about other devices in that range. It's an entirely different paragraph. Poorly worded by the author, yes - but still not wrong...
  • Poor Equipment (Score:5, Informative)

    by Bonker ( 243350 ) on Sunday June 02, 2002 @07:54PM (#3628204)
    The company I work for used a wireless link to get a 45mbit/sec data connection between our two offices for more than a year. Different businesses in the same building initiated wireless links after seeing the sucess we had with ours. One, which was aimed at a nearby wireless ISP was illegally overpowered and wiped out our connection regularly, despite the fact that the dishes weren't even facing the same direction. The other, which made a very short hop, was apparently on poorly configured equipment and would also play merry hell with our shot.

    IANAWE(I am not a wireless engineer), but I can't help but feeling that if we're to see the 'unlimited spectrum' as it's been mentioned before, then equipment manufacturers are going to have to do a hell of a lot better job of making wireless kit that minimizes signal bleed.
    • You can have good or cheap. Good microwave equipment is expensive.

      This is also the reason that most microwave bands are regulated and licensed. Frequencies need to be coordinated. Equipment needs to meet certain minimum standards. Power levels need to be set at the minimum level that provides a reliable link.

    • Re:Poor Equipment (Score:5, Interesting)

      by Cef ( 28324 ) on Sunday June 02, 2002 @09:49PM (#3628528)
      With point to point links you really need to evaluate antennas and your area. Many people use antennas with a wider radiation distribution pattern than is necessary, simply because it does the job. A number of cheaper antennas also have terrible front-to-back noise ratio, so noise from behind or the side of the antenna can really affect the signal. Also remember that many antennas allow you to orient the polarisation of the signal by the way they are mounted, and some antennas even have circular polarisation.

      With general network setups (eg: an office) many people have a tendancy to put an AP on the edge of the building, particularly in warehouses (simply because there is little else to support it). Semi-directional antennas (with 60-180 degree coverage patterns) are VERY useful for walls and corners, and usually have a higher gain in the direction you want (away from the wall or corner, into your business). The less signal that escapes your premesis, the less chance of interference, and also the harder it is to get an outside connection (ie: war driving).

      If your setup doesn't allow for outside interference, and is very succeptable to it, you'll always have problems.
    • IANAWE(I am not a wireless engineer), but I can't help but feeling that if we're to see the 'unlimited spectrum' as it's been mentioned before, then equipment manufacturers are going to have to do a hell of a lot better job of making wireless kit that minimizes signal bleed.

      IAAWE, and you can't expect the equipment manufacturers to fix the problem, because as the specs are written all of the original equipment works perfectly. All of this equipment has to pass field tests before it can be manufactured and sold. The problem is that you get some clueless dork who either (A) doesn't know anything about wireless systems or (B) doesn't care, to plug in a amplifier and overdrive it into compression, at which point the signal bleeds into all the adjacent channels wiping out all the nearby networks (I can assure you a LOT of engineering work goes into controlling adjacent channel power, and it is VERY easy to destroy this by hooking up a crappy amplifier). End result, you end up with a powerful signal spanning the entire band (and for those who really don't care they plug it into an omnidirectional antenna to spread the joy...)

      The root problem is that you have average people putting together an ad-hoc cellular network without any knowledge of how to do such a thing, and typically not working as a group either, but as individuals, with each individual wanting to have an optimum connection at the expense of the others. Now you could argue that equipment should be even lower-powered to avoid interference, but this only makes it more susceptible to real-world intereferers (the microwave ovens and rainstorms), and still doesn't solve the problem of the guy with the overpowered amp.

      Unfortunately this problem will only follow into the 802.11a band, as it is irrelevant what particular frequency your using (again the root problem is network design). For now you just have to negotiate with your neighbors to get an optimal setup (assuming you can find them, simply explain that the connection will be better on both sides if your not stepping on each other).

      As an aside, this has particular serious issues when you think about it in the context of UWB (ultra wideband) equipment .. can you imagine when UWB appears, how long will it be before someone tries to amplify that, and starts blasting ALL frequencies .. not pretty .. and I seriously doubt the FCC will be able to police it...

  • What?!? (Score:3, Funny)

    by Peridriga ( 308995 ) on Sunday June 02, 2002 @07:56PM (#3628213)
    What the hell about this article [slashdot.org] about the false theory of spectrum scarcity no less then 2 hours ago?
    • Re:What?!? (Score:3, Insightful)

      by Detritus ( 11846 )
      It's bullshit.

      Yes, we can greatly increase the efficiency of spectrum utilization for some applications if we toss out all existing models of spectrum use and their associated equipment, spend huge amounts of money on software defined radios, develop new suites of protocols, and mandate cooperation between all users.

      • The problem with the idea of unlimited spectrum is that while it is true that there is no interference between EM waves in free space, that is not true once they hit your antenna. Then all the different waves on a particular frequency will interfere like crazy.

        The only way to allow multiple use is with exotic directional antenna concepts like phased arrays. Sure, with a perfect directional antenna you can have as many transmitters as you want on one frequency; you just aim perfectly at the one you want to listen to. But of course directional antennas are unworkable for a mobile solution, and they are complicated and expensive to set up for a stationary one.

        Really that earlier article was just an attempt to bash the FCC with some theoretical results that don't have much to do with the real world.
    • And there is even another slashdot article [slashdot.org] on this "false theory of spectrum scarcity"
  • ...we turned this "congestion" into "p2p cooperation" by using the same protocol in which we all routed each other's data.. rather than dreading interference, you'd PRAY that the guy a block away set up a wireless network, so you could hop through him to that evasive Internet access point...
  • Conflicts sometimes occur also at 902 to 928 megahertz, used by older cordless phones and some military radar. Ricochet Networks Inc. plans to launch a wireless service in major cities using that range as well.

    I think the author needs to get in touch with the times! ;-)

  • There is an amateur radio band between 902 and I think 908 MHz, the 33cM band. Certainly not ungregulated.
    • Part 15 devices may operate from 902 to 928 MHz with certain power and bandwidth limits. Hams use the same spectrum and are permitted more power, but must not interfere with the primary users (ISM, vehicle monitoring systems, and government allocations). Furthermore, parts of Colorado, Wyoming, Texas, and New Mexico are off limits to hams at 33 cm.

      Another ham band, 13 cm (2.30-2.31 GHz and 2.39-2.45 GHz), overlaps the Part 15 spectrum at 2.435-2.465 GHz.

      Theoretically, hams (and everyone else) have priority over Part 15 devices, but just try explaining that to an angry neighbor.

      The complete amateur radio regulations for the USA can be found here [arrl.org]. The USA is in ITU region 2, except for some Pacific islands in region 3.

      • I don't believe the 2.4 GHz ham band overlaps with the ISM band in the USA - It's directly adjacent, I think.

        The Australian (Maybe another country) 2.4 GHz ISM band is a different story - There's an article for hams on hacking old Proxim Symphony cards that said that if you send in a photocopy of your ham license, Proxim would send you a card normally only legal in Australia.
  • ...of this story [slashdot.org]
  • by PhotoGuy ( 189467 ) on Sunday June 02, 2002 @09:37PM (#3628483) Homepage
    I have a 2.4 ghz IEEE 802.11 wireless network in our house. Works great. (All Lucent cards.)

    We have a 2.4 ghz phone, with also works great, but when we're on the phone, the throughput on the wireless lan goes down, and similarly, if there's a lot of wireless lan traffic, the phone gets interference. Tried different channels.

    Tried out a wireless video relay from Radio Shack which uses 2.4 ghz. The wireless lan (even idle) causes regular noise on the screen, making it unusable. It went back.

    Most annoying of all, when our microwave is on, the wireless lan loses most packets, and is almost unusable in the kitchen (and some other places).

    The frequency hopping and co-existence in this band doesn't seem to work out as well in practice as it does in theory, unfortunately.

    • I have noticed that when the microwave is on (and my laptop is in the kitchen with me), things like telnet sessions on 802.11 work fine. However, applications that require transfering longer packets (for instance, MP3 streams) get clobbered. I suspect that this because the longer the packet is, the greater chance it has of being corrupted.
    • You mention that the frequency hopping does not work as well as in practice. Lucent however, is a direct sequence solution, not frequency hopping. 802.11 provided for both techniques, but anything Wi-Fi, one of which is Lucent, is using the Direct Sequence technique.

      This is unfortunate actually, as a good fh radio would be much better at avoiding the interference.

      As a side note, I work for a wireless company involved with all sorts of wireless networking from good old UHF and 902 MHz up to 802.11a. Even we suffer from the interference that our microwaves, lights, etc. generate. Maybe it's time to go back to a regulated spectrum...
    • What the fuck do you expect when you put a 1200W transmitter next to a 0.03W transciever? Just be glad that you don't fry your laptop.
  • From the article: "His solution: Get his neighbors to space out frequencies they use."

    Screw the neighbors ... let them all share the congested default frequency and just move yourself as far off in the other direction as possible. :) After all, he's the one that thought of it.
  • WiFi is at 2.4 GHz (Score:3, Informative)

    by Tjp($)pjT ( 266360 ) on Sunday June 02, 2002 @09:58PM (#3628564)
    And is an unlicensed user of the spectrum. Fortunately current technology can compensate.

    At 900 MHz Government and vehicle location are primary, and amatuers are among the secondary authorized users. Part 15 devices just add to the noise that other services must overcome.

    In both bands, amatuer operations are swamped, if low power, by the increase in the noise floor. However, amatuers can operate on those bands with enough power using the same spread spectrum scheme such that the WiFi would be useless for PArt 15 devices. But its unlikely given the nature of the amatuer radio service (recently the FCC relaxed the allowable spread spectrum/frequency hopping restrictions on amatuers).

    This is where that portion of the FCC regs. for Part 15 devices is critical, in that they must not create interference for the licensed users of the spectrum and must accept interference from them. Not an exact quote, but you get the drift.

    In a nutshell, if you use unlicensed devices in spectrum where other services are authorized for higher power, you get what you'd expect. Now 5GHz is a great place to be! BTW when I key up on 2.4 GHz with 10 watts, my 802.11b network shuts down pretty hard. With only 50 feet or so of seperation the front end of the WiFi receivers gets overloaded even though I am not all that close in frequency, it is just the radio circuitry in the WiFi devices is just barely adequate so they can meet their price point and comply with the FCC regs. Better frequency agile receivers could be put in the devices and most likely will be as more devices crowd in. Also automatic power control will get better and the potentially they'll create a third scheme for the spread spectrum use that is more adaptive and as such would accomadate more users.

    Last, everyone knows that they can change the channel their network is on, right. I have found several swamped WiFi networks all clashing on channel 1 when there was plenty of usable spectrum up the band. (Powerbooks are great portable diagnostic tools even though the UI is cheesy for the Airport software and the third party tools are scarce due to lack of internal Airport info.)

  • by HiyaPower ( 131263 ) on Sunday June 02, 2002 @10:08PM (#3628590)
    The standard 802.11b usually is preconfigured to be on channel 6. Do yourself a favor, change it when you install your network to something else... The average folks will just plug in the WAP and let it run on that channel. You can have a brain and not compete there.
  • Excuse me for erroneously stating that it was 902 to 928MHz. So I made a mistake, shoot me.
  • What's so special about these presentations?
    Yes - a cellular/trunked model will enable greater use of spectrum. This has been well known for the last twenty years.
    Yes - spread spectrum/ultra-wide band allows re-use of the same spectrum.
    BUT the price you pay (for cellular or spread spectrum) is gradual degradation of service with increased users.
    Yes - radio waves do "pass through one another" allowing spectrum re-use, and that's been known since beam antennas came into use in 1919.

    These presentations are simply examples of special pleading by commercial interests. Some corporations believe that the law of gravity could be repealed if they lobby hard enough. Everyone wants a chunk of the radio spectrum and non-one wants to pay for it or show responsibility to other users.
  • by timothy ( 36799 ) on Sunday June 02, 2002 @11:11PM (#3628838) Journal
    (somewhat informative: http://www.freespaceoptics.org -- one of many sites on the topic, but one which had a nice pic near the top ;) )

    The site I can't find quickly (anyone?) is one that I know has been mentioned on Slashdot a few times, home-built optical transmitters (In the Czech republic, IIRC) using modified ethernet cards and powerful LEDs to beam multi-kilometer distances ...

    5 years ago I would not have guessed how widespread and cheap 802.11 stuff would be today; right now, you (point of reference, Americans in the lower 48) can get an 802.11 base station for under $100. Glut isn't quite the right word, but lets say there's *a lot* of somewhat decent, moderately versatile wireless gear available for what is in 1st countries not a huge chunk of disposable income, at least for folks middle-class-and-up. The cost of 7 cds gets a working base station ...

    Wouldn't it be nice to see a similar flood of products for optical gear? Yes, there will be lawsuits (eye damage! you hurt my eye!), and ugly warning labels, and ISP crackdowns for retransmission and who knows what else, but ... I think it will happen. Wait til last year's optical gear is on clearance at Walmart ;)

  • RF interference? (Score:2, Interesting)

    by Wierd Willy ( 161814 )
    My pop solved this problem last year, with copper mesh underneath the new siding he had put on his house. He also limited the nework to only a smaller area, running printers and such. And the copper mesh wasnt all that expensive. He now is interference free. The trouble is, he also has to go outside to use his cellphone, and the cordless phone wont work outside the house. Trade-offs are a bitch.

  • by Anonymous Coward
    Check it out, Zhrodague WiFi Mapserver [zhrodague.net] is online, and almost ready for prime-time. We have a US map loaded, and more detailed maps for Pennsylvania, and Massachusetts. Upload your netstumbler data, and see it plotted on the map. Part of the Pittsburgh Wireless Community [pghwireless.com].
  • Not that i like governmental involvement, but perhaps this is one time the FCC should have been involved.

    Left to their own, people dont share..
  • Anyone ever heard of Usurf America?

    Well I used to work for them and they were trying to bring WiFi to the consumer at about the same rate per monthas DSL/Cable.

    It's funny that it didn't take off, but mismanagement of company resources and firing your entire Tech. Support Dept. Doesn't help.

    It seems like many of the microwave devices are of somewhat low quality anyway, I recall the connection was supposed to have 1.5 MBps up and down, but was never faster than a 256/256 DSL. On top of that data loss and corruption was prolific.

    I think these companies should leave WiFi to Cisco (w0rd to your 802.11b) and research even higher frequencies so that in 10 years when the demand increases we wont all think back to the days of AOL 3.0 and it's loverly 26.4 KBps connections...

"my terminal is a lethal teaspoon." -- Patricia O Tuama