wireless g speeds - 22 mbps? 54 mbps 108 mpbs???

Discussion in 'Wireless Internet' started by Seth, Sep 3, 2005.

  1. Seth

    Seth Guest

    I have a question regarding wifi speeds. I am buying a wireless usb
    adapter for a new tivo and am looking for adapters.

    Netgear has a 108 Mbps adater, but I was trying to do some research to
    find out if that is a marketing gimmick. I had thought that 54 Mbps
    was the maximum thruput, but I was reading on cnet that 802.11 g specs
    are:

    20Mbps 150 feet range.

    How can wifi g adapters give 54 or even 108 Mbps? Is this done through
    duplexing?

    They say it's compatible with any wireless g device, so I don't think
    they're using any kind of proprietary boosting technology.

    Any info would be helpful and appreciated.

    Thanks,

    Seth
     
    Seth, Sep 3, 2005
    #1
    1. Advertisements

  2. Seth

    JB Guest


    I think you have a two questions here:

    What speed can I get with a 108 adapter on TiVo?

    Answer: about 22 Mbps, because the TiVo doesn't support Super-G mode on that
    USB adapter. You need the latest PC driver for that.

    Why do network companies use bogus marketing terms?

    Answer: 108 and 54 are like the perfect date -- it's not even theoretical
    possible, because there are too many variables. But the terms do have an
    underlying meaning. It's usually about a quarter to a half for 54, 108 and
    125 listed speeds.
     
    JB, Sep 3, 2005
    #2
    1. Advertisements

  3. Seth

    David Taylor Guest

    Answer: 108 and 54 are like the perfect date -- it's not even theoretical
    54Mbps is the signalling rate, not the data throughput rate. It's not
    the same thing.

    David.
     
    David Taylor, Sep 3, 2005
    #3
  4. Seth

    Seth Guest

    First, thanks to both of you for your input.

    So now I have two questions. One practical question and one question
    out of curiosity.

    First question is, for Tivo, which adapter do you recommend? Netgear
    (or other brand's) 54 Mbps G adapter?

    Second question is, what is the difference beteen signalling rate and
    thruput rate? Is it that signalling rate is the rate at which data is
    being sent out of the usb adapter and thruput rate is the "actual"
    effective rate being received (which would be affected by interference,
    collisions, dropped packets, etc)?

    Thanks!

    Seth
     
    Seth, Sep 3, 2005
    #4
  5. Seth

    johnny Guest

    All I have to say about this subject is that any wireless G stuff that
    goes beyond 54 Mbps is using technology that isn't a standard - in other
    words: proprietary. I'd stay away from that stuff even though the
    increased throughput is tempting.

    As for the 20Mbps rate at 150 feet - the bit rate declines as you get
    farther away from the AP.
     
    johnny, Sep 3, 2005
    #5
  6. Seth

    David Taylor Guest

    Second question is, what is the difference beteen signalling rate and
    No, signalling rate is best described as the bit rate while actually
    sending bits. Pretty much like the speed at which you talk could be
    described as words per minute, however in conversation, you don't talk
    continuously without breath, punctuation or waiting to see if anyone
    else wants to say anything. If you could talk continuously then the
    signalling rate would be the same as the actual throughput but the real
    number of words you get out a minute, although spoken at a particular
    rate, is not the same, that's your throughput.

    Same as on a network, the hardware device signals at a certain rate, on
    ethernet it could be 100Mbps, devices receive at the same rate, you
    can't have devices sending at any old speed otherwise the timing just
    doesn't work. However there are gaps in network traffic so when you
    measure actual bytes throughput of a file transfer, it's not the same as
    the speed that the thing talks on the wire.

    On wireless, the data is in bursts @ say 54Mbps signalling rate although
    there are large periods of silence (relatively speaking) so throughput
    is lower.

    Add to this the fact that wireless with a single radio is half duplex so
    that cuts down your throughput then factor in protocol overhead and it's
    no wonder that you don't get 54Mbps throughput even though the radio is
    chirping away sending data in 54Mbps bursts.

    David.
     
    David Taylor, Sep 4, 2005
    #6
  7. Seth

    Seth Guest

    David,

    Thanks for the in depth description. I think I understand the
    difference betw. signaling rate and throughput rate.

    Now the question is, if a wireless G adapter says that it "signals" at
    108 Mbps, does that mean that the throughput will be higher than with a
    54 Mbps adapter? I know neither one will have the 108 throughput, but
    just wondering if the higher signaling rate on the 108 adapter will
    result in higher throughput. Or is it limited by the access point I am
    using? Not sure if access points have a Mbps signaling rate or if they
    just conform to a wireless standard.

    Thanks,

    Seth
     
    Seth, Sep 5, 2005
    #7
  8. Seth

    David Taylor Guest

    Now the question is, if a wireless G adapter says that it "signals" at
    It should provide for faster connection but there are other variables.
    Doesn't matter whether it's an AP or a PC adapter, the rate at which
    bits are transmitted has to conform to expected standards. The
    throughput is something else. No reason why you couldn't have a very
    fast transmission rate yet couple that to a crap processor, poor buffer
    and lousy encryption engine such that the bottleneck isn't the wireless
    transmision rate but instead just sends very fast bursts @ whatever rate
    but with long gaps in between which kills the throughput.

    Bear in mind that i'm providing example text, not figures. :)

    David.
     
    David Taylor, Sep 6, 2005
    #8
  9. Seth

    Seth Guest

    So basically, without knowing the other variables, I really can't know
    if the 108 will give me more throughput, right?

    I think I am going to get the 54 Mbps adapter, just for practical
    purposes. Tivo's website lists that model as "compatible", so if I
    have any issues with the setup or connections, I'd rather be able to
    say, "hey, I am conforming to your standards". :)

    But this is an interesting topic for me. By the way, where did you
    learn about all of this?

    Thanks!

    Seth
     
    Seth, Sep 6, 2005
    #9
  10. Seth

    David Taylor Guest

    have any issues with the setup or connections, I'd rather be able to
    Pretty much, that's what standards are supposed to be for. :)
    Originally? I did an electronic engineering degree at University.

    Although very brief, this is a pretty similar thing but discussing baud
    rate and telephone transmission although it still comes in to wireless,
    http://en.wikipedia.org/wiki/Baud in that originally a symbol state
    transition represented one bit and so up to 600 baud, data rate was 600
    bps. Then they started messing with phase too so you got to Quadrature
    Amplitude Modulation where 16 bits are transmitted per symbol state
    http://www.hait.ac.il/staff/commEng/Michael_Bank/qam/demo.html

    Wireless RF is just another set of modulation methods and this is what I
    mean about the standards being important, in order to be decoded, you
    have to have both ends using the same signalling scheme. They can fall
    back and forwards to different modulation methods, signalling rates but
    at the end of the day, how often those bursts of data are in the medium
    is what you're interested in if you want to measure throughput.

    Like I said, it's just like if you could read out loud the whole of a
    500 page book in 5 seconds. Only useful if someone else can listen at
    the same speed and not much use as far as throughput goes if you could
    only do it once a week and didn't have to rest before doing it again. :)

    David.
     
    David Taylor, Sep 6, 2005
    #10
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.