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Wireless Networking Hardware

How Reliable is 900Mhz Wireless Internet? 67

Posted by Cliff from the gauging-the-airwaves dept.
amrust asks: "I live in an area that currently is not being served by broadband in any way. Local ISP's are discussing bringing Wireless Internet into our area, and for some of the more difficult to reach places, they have mentioned 900Mhz being used. I was wondering how reliable/secure the 900Mhz spectrum is for Wireless Internet, and if anybody has some comments on experiences with 900Mhz wireless internet that they can pass on?"
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How Reliable is 900Mhz Wireless Internet? More

How Reliable is 900Mhz Wireless Internet?

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  • It's so reliable (Score:4, Funny)

    by Anonymous Coward on Thursday July 10, 2003 @09:48PM (#6411747)
    That I'm currently typing this comment usi

  • Frequencies (Score:3, Interesting)

    by hackwrench ( 573697 ) <hackwrench@hotmail.com> on Thursday July 10, 2003 @09:51PM (#6411772) Homepage Journal
    Any frequency is just as secure as any other. It depends on the protocols that run over it.

  • Phone Frequency (Score:5, Informative)

    by rritterson ( 588983 ) * on Thursday July 10, 2003 @09:52PM (#6411775)
    I don't have any personal experience with 900mhz, but i do know that it is the same frequency that cordless phones use. Some phones today use 2.4ghz and they cause interference with .11b and g (my friend's neighbor has a phone that is so powerful it knocks my friend offline everytime the neighbor turns it on.) There are many more 900mhz phones that 2.4ghz phones, so I'd assume the problem is worse.

    However, you are in a rural area, so maybe the congestion on that band will be somewhat less (We live in a major metro area).
    • Your friend should report his neighbors to the FCC because any 2.4GHz cordless phone is supposed to use spread-spectrum and therefore will not interfere with 802.11b.
      • I thought only the digital phones used the spread spectrum. The analog 2.5GHz phones didn't have to be...otherwise, wouldn't they advertise the spread spectrum feature on the box?

  • I would assume... (Score:4, Interesting)

    by twiztidlojik ( 522383 ) <dapplemac@m[ ]com ['ac.' in gap]> on Thursday July 10, 2003 @09:53PM (#6411787) Homepage
    That it would be more reliable to use the higher spectrum. If you can transmit 900 million waves/second, then you probably can't fit as much error correction in the stream as the protocols used in 2400 million waves/second communication due to the lower bandwidth of the 900MHz band. Then again, I'm just guessing. Any radio geeks want to take a stab at this?
    • I don't think this is true. Bandwidth is not directly proportional to frequency.

      It's not 2400 million waves/sec it's 2400 million peaks per second on a single wave.

      The major differnce is the depth to which the signals will penetrate, and their loss over distance.

      • Re:I would assume... (Score:4, Informative)

        by thebigmacd ( 545973 ) on Thursday July 10, 2003 @10:31PM (#6411987)
        Bandwidth IS directly proportional to frequency. Baud Rate (in the scientific sense) is exactly twice the frequency. @ 900 MHz, the bandwidth is 900 MHz, the maximum switching rate (BAUD) is 1800 MHz. tha Shannon Channel capacity, assuming 60 dB signal-to-noise, is 900e6log_2(1 + 1,000,000) = 17.9 Gb/s. obviously, this is extremely high. it is technically possible to hit this raw rate of data transfer. and it is impossible to exceed this value without data compression

        • Re:I would assume... (Score:3, Informative)

          by Anonymous Coward
          When they say "transmit at 9OO MHz" of course you can not send any real data if you transmit ONLY at 900MHz. Because that would be a single unvarying siqn wave at 900 MHz.

          Instead, you are allowed to vary around 900 MHz. I think the standard 900 MHz is really 900 MHz to 914 MHz.

          So 14 MHz is the WIDTH OF THE BAND, otherwise known as BANDWIDTH.

          At any particular center frequency you can set a wide or narrow range around it.

          I'm not even a ham or anything, come on guys I learned this by osmois somehow. You

          • Re:I would assume... (Score:3, Informative)

            by unitron ( 5733 )
            If the bandwidth is 14MHz then the center frequency above and below which the carrier will vary would probably be 907 MHz. However 14Mhz is wide enough for about 2 and 1/2 regular television channels, so for a telephone call, which only needs 0.0027 Mhz of bandwidth, I expect that only a small part of that 14 MHz is used with the rest available for other cordless phones in the same area.

        • Re:I would assume... (Score:3, Informative)

          by n9hmg ( 548792 )
          Bandwidth IS directly proportional to frequency
          What?
          <SARCASM>Wow! I can do morse code at only about 8wpm (which equates to about 40 baud) on 80M. Does that mean that I can do 856wpm on 70cm?
          ...and WOW! I can crank up my 1200baud packet system to 3600baud by just switching from 2M to 70cm. Thank you, oh great radio genius!</SARCASM>
          Sorry, but that's such an offensively ignorant statement from a member of a very technically-savvy group that I have to go off on it a bit. Frequency occupie
        • I'll admit I don't know a whole lot about this, but can't you get more than 1 bit per baud by using something like QAM?
        • Impossible, no, line of sight with antennas at angles could exceed this value.

        • frequency != bandwidth (Score:3, Informative)

          by js7a ( 579872 ) *

          @ 900 MHz, the bandwidth is 900 MHz

          On the contrary, as has been pointed out, frequency is not bandwidth.

          it is technically possible to hit this raw rate of data transfer.

          Actually, it is possible to approach [google.com] the Shannon channel capacity the way you calculated it, but impossible in practice to achieve it. Technical possibility is not the same as theoretical maximum throughput.

        • If you could commandeer all RF 0-900MHz, then you could transmit 900MHz worth of signal. You need bandwidth to convey the information, and the channel capacity is the width of the band. If you aren't baseband, you modulate. 900MHz phones use frequencies near 902-928MHz (I forget), divided into 80 discrete channels of 25 kHz each. Each cordless actually uses two channels to acheive full duplex mode, and not all manufacturers use all 80 channels in each phone, so collisions are possible.

          Anway, the phones don
        • you don't know anything about RF. This is the CARRIER FREQUENCY (900MHZ). The data rate in bits per second (baud) determines the deviation and band-width of the signal. In no circumstance have I EVER seen bandwidth exceed 1/8th carrier frequency for free-space signals. To get 17GB/s you would need a carrier deep in the microwave spectrum, and an extremely efficient DPSK or QPSK digital modulation. Your mathematical analysis is nice, but completely based on you plugging in numbers without knowledge of what t

    • Re:I would assume... (Score:4, Interesting)

      by dJCL ( 183345 ) on Thursday July 10, 2003 @10:02PM (#6411845) Homepage
      Based on my phone experience, I've owned and generally used both a 900 and a 2.4 phone. The 2.4 sounds better close in and can get a good secure connection to the base station within about 100+ meters of my base station. On the other hand, my 900 was quite capable of connecting to me when I was over 250+ meters away. The connection quality was pasable, but the range was great.


      The reason they are probably using 900 is for connection distance. The same equiptment will cover more users with probably less bandwidth, but that is a price to pay.


      As someone else noted, security of the connection has nothing to do with the frequency, so just discuss that with the provider. As it is, still 80% of the wireless networks that I run into are even setup with WEP(mine is not, but I have other ways) and most are default settings, so if the provider even tries to put in some security, no one will bother with them unless they have a reason.


      Enjoy!

      • Re:I would assume... (Score:4, Informative)

        by innosent ( 618233 ) <jmdority.gmail@com> on Friday July 11, 2003 @02:19AM (#6412887)
        The important factor here is how efficiently the signal can pass through a medium, and how directional the signal is. We don't live in a vacuum (if you didn't know this, you might need to get out once in a while :P), and therefore any signal sent has to travel through any objects in its path, including the air. Not sure exactly off hand which law of physics covers this, but lower frequencies lose less energy when passing through a medium, and are also less directional. Think about sound here, a low frequency (bass), say 40Hz will have relatively no problem passing through an object, like a car driving in front of your house at 2:00A.M., but a high frequency (treble), for example 10kHz is highly directional and has great difficulty traveling through objects.
        I believe this is due to the fact that to pass a signal through a medium, the particles in the medium must be excited to the same frequency as the signal, and it takes significantly less energy to excite a material at a lower frequency than it does at a higher one. Higher frequencies give higher fidelity, but are less resistant to signal loss.
      • Heh. My 2.4GHz phone got interference whenever someone used a microwave oven nearby. =)
    • One thing to add, though, is that the higher the frequency, the more "noise" you will have to deal with. I'm not really sure at what kind of filtering processes are used to combat this, but I have noticed that some 2.4Ghz phones have a lot more static than the 900 ones.

  • It's perfectly secure (Score:5, Funny)

    by anthony_dipierro ( 543308 ) on Thursday July 10, 2003 @09:59PM (#6411820) Journal
    All the sniffing software is written for the 2.6Ghz range, so you can rest assured that no one other than you and the intended recipient will be able to read the message.

    • Re:It's perfectly secure (Score:1, Informative)

      by Anonymous Coward
      Nice troll.

      But I'll bite.

      First of all, its the 2.4Ghz range.
      Second, security through obscruity is complete rubbish, 'no one other than you and the intended recipient will be able to read the message' is a load of, quite frankly, bollocks.

      Mod this down.. no need to give trolls karma.
      1. IIRC, 802.11b is 2.4GHz.
      2. It's a question of hardware, not software; most current wardriving software has support for other systems such as 802.11a and g as well as b. In theory, they could also sniff on 900 MHz if there were 900 MHz cards that supported the right software interfaces.
      3. Remember that there's much more to a secure connection than just the "last mile" from your ISP to you. Depending on the network itself for security is risky at best. To really ensure security, you should always assume that

      • To really ensure security, you should always assume that your neighbors, your local bank robbers, and the NSA are all snooping on you, and simply encrypt anything important.

        No, to really ensure security, you should always assume that your neighbors, your local bank robbers, and the NSA are all snooping on you and they have your encryption key.

        If it's that important, you shouldn't be transferring it over the internet at all.

        • If it's that important, you shouldn't be transferring it over the internet at all.

          Right, but that kinda defeats the purpose of the question. ;-)

          But yes, I do agree that crypto is nowhere near a bulletproof suggestion (literally, if you're talking DoS attacks). For it to be of any use, you still need basic smart computing practices: don't give out your passphrase, don't install a Trojan horse, keep your computer in a secure physical location, etc. But the fact of the matter is that just using SSL for

      • WEP isn't for protecting data. It's for giving the war driving script kiddies a reason to use my neighbor's wireless network instead of mine. Wireless security is a race to the bottom and as long as you aren't running downhill as fast as the rest you're pretty safe.
      • I can relate to #3. I can ARP-poison the gateway of my ISP (wireless over 802.11b) and get EVERYTHING. Passwords, mail (someone's using our mail gateway to relay spam :), IM, you name it. Worse, my school doesn't let me have encrypted POP/IMAP sessions, so I can't make my data safe. Time to setup some SSH tunnels, I guess :(

        What worries me more is that anyone with a pringles can and a wifi card can sniff the connection!

  • Try Google groups (Score:5, Informative)

    by klui ( 457783 ) on Thursday July 10, 2003 @10:08PM (#6411880)
    Just picking up from the first page yields some tidbits. Range, reliability [google.com]; Interference. [google.com]

  • 900 mhz is just as good (Score:4, Informative)

    by r00tdenied ( 540333 ) <josh@pla t i n u m - n e t works.com> on Thursday July 10, 2003 @10:29PM (#6411978) Homepage

    Most WISP's use 900mhz where there is a substantial amount of tree cover. 900mhz can penetrate the tree canopy much easier than 2.4ghz because of the wavelength.


    2.4ghz has a problem with dense water, and in tree leaves their is significant amount to cause multipath reflection. Multipath reflection is caused when the wavelength of any given radio signal is short enough to be relected by the water molecules.


    At 900mhz the wavelength is much greater than 2.4ghz so it doesn't have as much difficulty.

  • Anecdotal (Score:5, Informative)

    by Jahf ( 21968 ) on Thursday July 10, 2003 @11:20PM (#6412191) Journal
    I listened to Bill Joy talk at a conference in Aspen where he went into fair detail about the 900MHz system they had installed there long before 802.11b came about (if anyone remembers seeing a story about an Aspen cabby with a totally connected neon taxi cab, he was using this system for his net access).

    Anyway ... for long distance penetration through anything other than air, 2.4GHz plain sucks (I'm using a WISP now and occasionally when strong winds hit I have to give up working for awhile ... shame). Mr. Joy did mention that they weren't able to get more than a few hundred Kb/s out of their system, but that was acceptable for a few dozen people sharing a single T1 and the system sounds like it was rock solid stable.

    If you only have one choice (or if you consider a normal dialup line a choice maybe 2) then that is definitely not a bad one. I think I would actually prefer my 2.4GHz ISP to offer 900MHz as an option. Instead they're switching to 5GHz for high-end use ... though since their 5GHz access point doesn't have trees between it and myself and it is far less war driven I will probably switch to that anyway.

  • Many types of "900mhz wireless" (Score:3, Informative)

    by RALE007 ( 445837 ) on Friday July 11, 2003 @01:11AM (#6412690)
    There are multiple wireless standards that operate within the 900mhz range. Without knowing which standard at 900mhz your local ISP's are considering, one cannot comment on the security or reliability of the unknown methods of communication that may be implemented in your area.

    I would recommend digging a little deeper to see what standards are being considered, then visiting this very informative page at IBM.com [ibm.com] pertaining to current and emerging wireless standards. Once you know the exact standard the ISP's are considering, you should be able to have your questions concerning security and reliability answered on the IBM link provided.

  • Totally different approach. (Score:4, Informative)

    by WasterDave ( 20047 ) <davep AT zedkep DOT com> on Friday July 11, 2003 @01:30AM (#6412740)
    [disclaimer: the following is based on research, not personal experience]

    So, I've been looking at using 900MHz for some low bandwidth stuff. Primarily because 2.4GHz can be a PITA to deploy - near line of sight (over distance), trees, rain etc.

    Anyway, it appears that the products available round 900MHz have taken a completely different, and much more "agricultural" approach to the problem. Basically they're 900MHz FM radios with a modem bolted on. No clever multipath resolution, no time division, no orthogonal frequency division (outside that which the modem does). Consequently the amount of bandwith available is about seven eigths of fuck all - a claimed 115Kbit (being the limit of the RS232 connectors they use) - with something rather worse being the practicality of situation.

    Security is kinda interesting though. Quite a lot frequency hop across a range of channels within the spectrum. It appears that you need to get both radios, from the same manufacturer, and put them on the same hopping scheme before they'll talk.

    Dave

  • good and cheap (Score:4, Informative)

    by akb ( 39826 ) on Friday July 11, 2003 @01:55AM (#6412818)
    Ricochet ran a well regarded service over 900mhz. They claimed 1 mile range from base stations, w/o line of site. So it is certainly possible to build a reliable service.

    Urban environments have a fair amount of 900mhz interference, in a rural setting you are probably much better off. Heck, w/ all the 2.4ghz phones being sold I wonder if 900mhz is clearing up some.

    There's a whole lot of cheap equipment around. I got 3 900mhz DEC Roamabout pcmcia nics for $12 (inc shipping). They are 2mbit and the linux driver worked perfectly.

    Many houses have old directional antennas for UHF TV that aren't used anymore because of cable / satellite. I've found a fair amount of these range up to 900mhz. So maybe you've already got an installed antenna and cable run in your house. If not you probably know someone who has one they aren't using or can pick one up for cheap.
    • Where did you purchase the cards from?

      -Jonathan
    • Note the keyword "claimed" to have one mile, even without LOS...

      I'll be honest, I never worked with the Ricochet stuff. Right now, though, my company [mvn.net] (small local ISP, we also do wireless) does have some of the Waverider [waverider.com] 900MHz hardware deployed. We have FOUR customers using it, as opposed to several hundred using the 2.4GHz stuff. Heck, I'm about half a mile away from one of the Waverider CCUs (basically, their equivalent of an access point), and I have to deal with the competition [charter.com] for my broadband becau

      • oddly i work for a WISP not far from the hometown of mvn.net ... and we use the waverider stuff. we have good luck out of it, most of our customers are on it as opposed to the 2.4 (although 2.4 definately has more bandwidth to play with). dont use the damned 6db internal window mount antenna and you will be fine.
  • so I'm sure it's doable..

    TechTV article about Metricom modems [techtv.com]
    next

  • ISM (Score:4, Interesting)

    by Detritus ( 11846 ) on Friday July 11, 2003 @05:52AM (#6413384) Homepage
    900 MHz is an ISM (Industrial, Scientific, Medical) band, like the 2.4 GHz band. Unlicensed devices may not cause interference to licensed users and they must accept interference from other devices. This means that you are at the bottom of the totem pole in a "junk" band. If you can't use your unlicensed 900 MHz device due to interference, tough shit, that's the price you pay for unlicensed operation in an ISM band. Devices designed for ISM bands are usually designed with low cost as the primary design goal. That often means that there is no shielding and the RF electronics function poorly, or not at all, in a hostile RF environment.

    The end result is that you should keep your expectations low. If it works, great, if not, try something else.

    • Re:ISM (Score:4, Interesting)

      by Muad'Dave ( 255648 ) on Friday July 11, 2003 @08:34AM (#6413880) Homepage

      Amen to that, brother! As a part 47 user of 902-928 MHz, I have to deal with part 15 users noise. My local power company, Dominion Resources [dom.com] (aka VA Power) just installed some Schlumberger C1SR meters [goslb.com] in my area. They're the kind that transmit usage data on 910-920 MHz as a part 15C device. As far as I can tell, they broadcast their info every min or 5 min instead of being polled - aargh! My whole neighborhood now has lots of meters blasting away for 99 44/100% of the month when there's no meter reader truck around to hear them. I could be a nasty boy and demand their removal if they interfere with my part 47 use - we'll see how bad it really is after I get a chance to quantify the interference.

      Of course, searching for manufacturer code F9C, product ID C1R-1 on the FCC Product ID Search page [fcc.gov] returns little useful info regarding the exact freqs and modulation techniques in use. They asked for and received confidential status on the most interesting bits. Ugh.

      PS - The FCC product ID search page can return all sorts of useful info on any product with an FCC ID. For instance, the info on the electronic key for my car returns schematics, data format info, etc. Sweet!

  • I have found 900 mhz to be very reliable. I connect to network at University from home using 900 mhz network equipments. Sometime service is down for an hour here or there but this may be more because of problems at the University network.

    In China, we have ways of making sure wireless space becomes not over crowded. Crowded could be a big problem because of the population, billions of people! Only top academic, scientist and politican can use wirless networking in my city, because otherwise it'd be overcro
  • for asking this question. I am considering setting up my own WISP on 900 MHz in my area.

    I live in a broadband-less rural part of Canada lots of hills, forest, rabbits, etc. and 2.4 GHz probably would not stand a chance.

  • I'm currently with a 5.2 GHz WISP (Score:3, Interesting)

    by leifw ( 98495 ) on Friday July 11, 2003 @11:15AM (#6415094)
    My home internet connection is with a terrific WISP [littleappletech.com]. I believe they use a 5.2 GHz radio band that is 128-bit encrypted. The service has been reliable; much more so than Southwestern Bell's DSL, but slightly less so than @Home's cable modem. The speed is also good (~85 KB/s) and resonably responsive (~80 ms ping to various points on the net).
    So while I can't comment on the 900 MHz band specifically, I can say that a WISP in general can be a good choice.

  • People have addressed the differences of 900 Mhz fairly well, but I thought I'd chime on my experience with 2.4 Ghz

    First, you will have to determine what you have in your house that is at 900 Mhz. I know all 4 of my cordless phones are 900 Mhz. I know this because I was having interference on my connection (40 percent packet loss) until I found the culprit. (the culprit was my X10 camera. We moved it to the new baby's room - we use it to check on the baby without opening the door - and the new nursery

  • I've been using wireless 900mhz net for about 7 months now. I've never had downtime due to the wireless itself. Weather has never been a factor and I live in Michigan. I have a 786/786 connection and i pay 30 dollars a month.. not to bad at all as far as i'm concerned! And i get every bit of my bandwidth.

    My cordless phone does stop my net but all i had to do was press 1 button on the phone to change the channel... no big deal.

    My latency is just as good as on cable.

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