802.11g vs 802.11n

Discussion in 'Wireless Internet' started by jrb, Dec 6, 2007.

  1. jrb

    jrb Guest

    Hi,

    I am trying to figure out if going to 802.11n from an 802.11g is really
    worth it. My internet service is listed as being upto 7MB. Any thoughts on
    the switch?
     
    jrb, Dec 6, 2007
    #1
    1. Advertisements

  2. jrb

    miso Guest

    The high speed wifi is more useful between local devices rather than
    interfacing with the internet. For instance, you might want to set up
    a media server, sending the video from your PC to TV.
    http://www.dlink.com/products/?pid=547&sec=1
    for example. These devices were G, but N are appearing on the market.
    I could see wireless network attached storage being draft N.

    I think all the wifi routers that have gigabit on the lan are draft N.
    That was the driving force behind me going N over G. I do stream
    music, but that is find using G. I will eventually get around to
    streaming video, so the N will come in useful.
     
    miso, Dec 6, 2007
    #2
    1. Advertisements

  3. jrb

    DTC Guest

    Even 802.11b at 10 Mbps would be adequate for a 7 Mbps internet connection.

    802.11g is rated at 54 Mbps and would be useful for faster file
    exchanges within your own network. While it uses ODFM modulation, it is
    more robust (more reliable at longer ranges and less with than optimum
    signal levels), that advantage is lost as it requires more than twice
    the signal level for the higher speed. Locking down 802.11g to 10 Mbps
    would give you a very reliable wireless network.

    802.11n could be considered an upgrade to 802.11g in terms of robustness
    and range.

    If your 802.11b networks works fine the way it is, there's no advantage
    in spending the money to move up to 802.11n.
     
    DTC, Dec 6, 2007
    #3
  4. Required reading on MIMO:
    <http://www.veriwave.com/gurus/index.asp>
    This is very much up to date.

    802.11n is all about speed. Great for video and massive local file
    transfers. Doesn't add much in the way of range. The rule-of-thumb
    is that 4 times the speed, will give you 1/2 the range. By the time
    you get to speeds greater than 54Mbits/sec, you're talking about 5 to
    10 meter ranges.

    However, that's for multiple streams (Airgo). To make sure that it's
    a total muddle, 802.11n Draft 2 includes beam forming and steering
    (Atheros and Ruckus Wireless), which for some amazing reason is
    classified as MIMO. It offers no speed enhancements, but does offer
    substantial indoor reflection and interference reduction. One thing
    that all the various MIMO mutations have in common is that you cannot
    easily add an aftermarket antenna (or antennas). If you can't get the
    range with what is supplied by the manufacturer, too bad.
    Ummm... nope. Thruput is roughly half the connection speed. An
    11mbit/sec connection would yield about 5Mbits/sec thruput, which is
    much less than the 7Mbit/sec internet speed. The message header for
    the OP shows that he's on Cox.net, which has "PowerBoost" speeds to
    about 10Mbits/sec for preferred and premier service levels. To
    utilize 10Mbits/sec thruput, he needs at least a 24Mbit/sec connection
    speed.
    Locking it down at 24Mbits/sec would be required to prevent bandwidth
    constipation at 10Mbits/sec thruput. However, that doesn't work too
    well. I've been recommending that locking down the speed to the
    slower OFDM speeds offers a reliability improvement in that the access
    point isn't constantly trying to go as fast as possible. That works
    well at the slower speeds (I use 12Mbits/sec OFDM). That will a bit
    slow for a 7Mbit/sec cable internet, but will not work if the OP has
    burstable service. However, my experiments with locking the speed at
    much faster rates (I was testing at 36Mbits/sec) has not been so
    wonderful. Packet loss starts to creep up. Susceptibility to noise
    interference increases. Signal loss and disconnects are more abrupt
    and of course, at a shorter range. It will probably work just fine
    for a closed room environment (coffee shop, conference room, bedroom,
    etc), but isn't too good when going through walls, floors, or in the
    presence of substantial interference.

    I haven't tried the same tests with any of the MIMO devices, so I can
    tell if MIMO adds anything. I doubt it because outside of fairly
    short ranges, the typical Airgo MIMO access point reverts to
    802.11b/g.

    Incidentally, many low end routers can barely move data at cable
    internet speeds, or handle many connections:
    Ummm... I hope you're not referring to the 2x, 4x, now up to 12x
    stickers that are appearing on the retail packages? When I see the
    manufactories run a BER/PER test, at various ranges and speeds, I
    might believe that manure. Meanwhile, some MIMO articles:
    <http://www.smallnetbuilder.com/content/view/30224/100/>
    Sure there is. There's great benefits to all the 802.11n Draft 2
    confusion. It's bad enough that most of what I buy is obsolete in a
    few years. With 802.11n Draft 2, I can buy products that are obsolete
    on arrival and with no guarantee of a later upgrade to the final
    standard. There's also no incentive to produce such an upgrade path,
    because that will cut into future replacement sales.

    Bah Humbug;
    E. Scrooge and Associates.
     
    Jeff Liebermann, Dec 6, 2007
    #4
  5. ~ jrb wrote:
    ~ > I am trying to figure out if going to 802.11n from an 802.11g is
    ~ > really worth it. My internet service is listed as being upto 7MB. Any
    ~ > thoughts on the switch?

    ~ Even 802.11b at 10 Mbps would be adequate for a 7 Mbps internet connection.

    No it would not. The maximum nominal signaling rate of 802.11b is 11Mbps.
    However, the 802.11 MAC layer has a lot of overhead, so even with a perfect
    11Mbps 802.11b physical/MAC layer, this will translate (at the IP layer)
    to a best case throughput rate of 5.5 - 6Mbps.

    So, 802.11b would be a bottleneck for a 7Mbps Internet connection.

    (Terminology note: when I say Mbps, by that I mean MegaBITS per second,
    where "Mega" denotes one million [1,000,000].)

    ~ 802.11g is rated at 54 Mbps and would be useful for faster file
    ~ exchanges within your own network. While it uses ODFM modulation, it is
    ~ more robust (more reliable at longer ranges and less with than optimum
    ~ signal levels), that advantage is lost as it requires more than twice
    ~ the signal level for the higher speed.

    802.11g OFDM is more robust, and with a perfect 54Mbps nominal signaling
    rate will yield an IP layer throughput of up to 27Mbps or so.

    ~ Locking down 802.11g to 10 Mbps
    ~ would give you a very reliable wireless network.

    10Mbps is not an 802.11g rate. You could cap 802.11g at the 24Mbps
    signaling rate which would give you a maximum throughput of about
    12Mbps, which should be sufficient to prevent the wireless link from
    being a bottleneck for your Internet traffic.

    However, if there are 802.11b-only clients present in your cell, then
    the 802.11g protection mechanisms may reduce your maximum throughput,
    such that your nominal 24Mbps signaling rate may no longer be sufficient
    to yield 7Mbps of throughput.

    Therefore, I would probably stick with the maximum 802.11g rate of
    54Mbps, unless you have reason to be that the clients and/or APs are
    doing a suboptimal job of rate selection and would therefore benefit from
    a rate cap.

    ~ 802.11n could be considered an upgrade to 802.11g in terms of robustness
    ~ and range.
    ~
    ~ If your 802.11b networks works fine the way it is, there's no advantage
    ~ in spending the money to move up to 802.11n.

    Roger that.

    References:

    Capacity Coverage & Deployment Considerations for IEEE 802.11g
    Cisco whitepaper
    http://www.cisco.com/en/US/products/hw/wireless/ps430/products_white_paper09186a00801d61a3.shtml

    When Is 54 Not Equal to 54? A Look at 802.11a, b, and g Throughput
    Article by Michael Gast
    http://www.oreillynet.com/pub/a/wireless/2003/08/08/wireless_throughput.html

    Aaron
     
    Aaron Leonard, Dec 6, 2007
    #5
  6. jrb

    jay lunis Guest

    Let me jump in here a minute.
    My interest in 'n' is, by far, more for the increased range.
    Are you, and others, saying the range is not that much greater?
    I need to reach wirelessly about 80-100 feet through 3 walls and one
    floor. My 'g' can't reach that far.
     
    jay lunis, Dec 6, 2007
    #6
  7. jrb

    DTC Guest

    I've heard of that with consumer gear. We lock the speed down for our
    tier two (three to six mile distance) radios to minimize complaints of
    widely varying speeds. At six miles, we can certainly throw a faster
    signal, but with only a 10 dB fade margin.
    Good grief no! Besides, I don't use the consumer crap.
     
    DTC, Dec 6, 2007
    #7
  8. jrb

    miso Guest

    Those photos prompted me to open my dead Netgear WNR854T. It uses a
    Marvel board. The interesting thing is they used ferrite chokes on the
    antenna coax.
     
    miso, Dec 7, 2007
    #8
  9. I just happen to dribble by Office Max. On some 802.11n products
    being sold, the box declared:
    4x the range. 12x the speed
    Sounds great? Well, they lie. (Everybody lies, but that's ok because
    nobody can understand the numbers anyway).

    First, you're NOT going to get both 4x the range and 12x the speed at
    the same time. If you believe the hype, it's one or the other.

    2nd, 4 time the range of what? Compared to what device and under what
    conditions? I'm a bit busy right now (leaky office roof) so I'm going
    to suggest that you do the necessary Googling and see if any of the
    vendors that use this 4x and 12x manure bother to specify test
    conditions on their web piles. They probably do, but see if it
    actually resembles something you can use for comparison. Look for at
    what range they did the test, with what error rate, and using what
    client device for testing.
    Neither can an 802.11n Draft 2 router go through 3 assorted walls of
    unspecified material and one floor of more of the same. If it's
    concrete, stucco, chicken wire, or aluminum foil backed insulation,
    you're lucky if it can go through one wall. The only way I know of
    going through 3 walls and a floor is with an electric drill and CAT5
    cable. If desperate, think about power line (HomePlug) or phone line
    (HomePNA) networking.

    Incidentally, my rule of thumb is where the 4x and 12x crap came from.
    The way Airgo style MIMO (spatial mux) works is to transmit multiple
    streams of data at the same time. So, if you're getting perhaps 100ft
    of reliable range at 25 Mbits/sec, then with Airgo style MIMO, you'll
    get two streams or twice the thruput. However, you can always trade
    speed for range. A 2nd stream will give you SQRT(2) times the range,
    if you drop the TOTAL speed of the two streams back down to the
    previous 25Mbits/sec. If you have 4 streams, and slow things down to
    25Mbits/sec, you'll go 2x as far. To go 4x the range, you need 16
    streams, which I don't think any of the current incantations are able
    to deliver. Similarly, if you're expecting 12x times the speed,
    you'll need 12 streams, which is also stretching things a bit. Of
    course the spatial mux is far from perfect and tends to create some
    self interference. Your mileage may vary.
     
    Jeff Liebermann, Dec 7, 2007
    #9
  10. jrb

    DTC Guest

    Increased range? sure...in an open environment.

    Bubble pack FRS radios can go 12 miles...from a mountain top down into a
    valley.
     
    DTC, Dec 7, 2007
    #10
  11. jrb

    jay lunis Guest

    Well, my walls/floors are typical residential wood/drywall.
    HomePlug has worked tolerably well but, since I tend to move around a
    room, I'd rather not be tethered to a wire. Is there a way to send a
    signal to a remote network device (wireless or wired) and have the
    remote device send a wireless signal so I'm not forced to connect my
    laptop to a wire/cable?
     
    jay lunis, Dec 7, 2007
    #11
  12. Got time to make a quick measurement? Fire up Netstumbler or anything
    that gives a signal strength graph in dBm. Lock the speed on your
    wireless access point to some fixed OFDM value.

    Walk around your house starting with going through 1 wall. Get an
    average signal strength value and record the straight line distance
    between the access point and the laptop. Try it again for 2 and 3
    walls. If possible, also try it in an open area, with no walls.

    What you should see is that doubling the distance, should cause a -6dB
    drop in signal level. Any loss in exess of this value, is attenuation
    in the walls. That will give you a real number to work with for
    calculating wall attentuation. I can help with the calcs if you email
    to me the setup and numbers.

    As for HomePlug and HomePNA, both have wireless bridges and repeaters
    that use the phone or power lines as a backhaul. For example:
    <http://www.netgear.com/Products/PowerlineNetworking/PowerlineWirelessAccessPoints.aspx>
    Both use the power line for a backhaul. One acts as a wireless
    repeater at both ends. The other uses wireless only at one end. The
    other end gets a CAT5 cable plugged into your router.

    Incidentally, with such an arrangement, you really don't need
    wireless. Your laptop is going to be plugged into the battery
    charger, which is plugged into the wall. You might as well run a CAT5
    cable to a HomePlug ethernet bridge using the same wall plug. No need
    for wireless.
     
    Jeff Liebermann, Dec 7, 2007
    #12
  13. jrb

    jay lunis Guest

    Not quite. I admit to being lazy. Don't want to unplug a bridge and
    take it to another outlet. Don't do that now with my battery charger.
    I sit/go wherever I want and use the laptop until I get a low battery
    alarm (which, in my case, is seldom). Often don't have a power cord
    attached to the laptop.
    But there is hope. I'll go to the link you provide and get the
    bridge/repeater. From your description, that should do what I want
    without moving to 'n' equipment. And it will save me from taking signal
    strength measurements.
     
    jay lunis, Dec 7, 2007
    #13
  14. I always wondered why people buy wireless devices. Now, I know.
    Some more products:
    <http://www.homeplug.org/kshowcase/view>
    Make sure you get at least the 85Mbits/sec HomePlug flavor. The
    14Mbit/sec flavor is just too slow. I haven't tried 200Mbit/sec
    (HomePlug AV) yet.
     
    Jeff Liebermann, Dec 8, 2007
    #14
  15. jrb

    Peter Pan Guest


    Think plan B... I have a linksys wrt300n downstairs plugged into the cable
    modem, and the router output to both a homeplug (14.4) and a netgear (85) on
    a power strip, so at any outlet in the house (or outside, when nice, by my
    hammock) .. I have the other parts of the homeplug and netgear plugged into
    wrt54g's that I got at walmart for under $50.. gives me both wired and
    wireless wherever I plug it in... Just a few caveats, plug the powerline
    stuff into the router part, have em both on the same 3rd ip addy/segment so
    it will let you see the rest of the network, and use a different
    ssid/channel so you don't wirelessly connect to the wrong one. Benefit is,
    that way I have both wired and wireless at any plug in the house, and any
    place that is a dead spot, I just plug the thing in and can get full
    internet and/or access to my local network... You gotta plug the powerline
    stuff in, so why not a power strip ($2) that not only does that, but the
    wap/router, and has extra plugs? Real handy when you want to move it all,
    just plug it in wherever you want Sounds like you already have the major
    pieces you need......

    Just to be clear, you could do it all wirelessly, but It was actually
    cheaper to get the wap/routers at walmart and have both wired and wireless
    by any plug....
     
    Peter Pan, Dec 10, 2007
    #15
  16. jrb

    jay lunis Guest

    I'm a little confused here.
    Plug the modem and router into an outlet away from the PC?
    I suppose this means the PC is plugged into a homeplug.
    And you have 2 networks ssid's? One for wired and one for wireless?
     
    jay lunis, Dec 11, 2007
    #16
  17. jrb

    Peter Pan Guest

    Nope, i have one wap/router downstairs connected direct to the cable modem,
    and that router output is connected directly to a netgear/85 (and several
    TB's of network storage).. At other places in the house, I have both a
    second wap/router and the second part of the ethernet bridge connected to
    the *router* parts of additional wap/routers (NOT the wan port), that I can
    plug in anywhere in the house, and essentially have another wifi ap (or plug
    cables into them if needed, like for my Tivo that wants wired - have 5 - 4
    can do wireless/USB, but 1 only wired-ethernet).. purpose for a different
    ssid/channel is so that instead of seamlessly roamng (and possiblly
    connecting or staying connected to the weaker one, I just use a unique
    ssid/channel rather than trying to putz with seamless roaming... As for
    multiple wap/routers, yes I happen to have several (tivo only use wep, so i
    want internet but not access to my other puters), so in the starting ip i
    have x.x.1.x and x.x.2.x (one private one public) So I do the ssid's to
    differentiate ppinmd-private and ppinmd-public)... had the powerline stuff
    already, and just picked up the linksys wap/routers for under $50 each at
    walmart (at under $50 a pop was easier to get the same thing, in case one
    dies I have spares)
    Is that clear as mud? :)
     
    Peter Pan, Dec 11, 2007
    #17
    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.