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Question about Wireless speeds.

Discussion in 'Wireless' started by Baba O'Riley, Jun 30, 2006.

  1. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    Howdy partners,

    OK, I don't think I've ever seen this question addressed before and it popped into my head this morning.

    Just say, for arguments sake, that a 54mbps wireless connection does indeed transmit data at 54mbps. Would two wireless clients connected to a WAP only transmit at 27mbps each, and four clients transmit at 13.5mbps each etc. or would each transmit at 54mbps? Does it depend on the WAP?

    Cheers.
     
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  2. Boycie
    Honorary Member

    Boycie Senior Beer Tester

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    that is a good question, baba! you would think so, but i am not sure. You would have thought the WAP could *switch* to keep the highest possible bandwidth on all clients.
     
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  3. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    You have that right. The bandwidth is shared between all the stations connected to the AP. And to make it worse, because of the overhead inherant in the protocol, a 54Mbps unit only ships about 25Mbps of data at the best of times.

    Harry.
     
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  4. zxspectrum

    zxspectrum Gigabyte Poster Premium Member

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    That is a good question and im looking for the manual so i can answer the question. We have a networking setup here . It consists of a 512k connection , and when we have the wireless router im getting 256 and so does the landlady, but that is the braodband etc. Now im thinking that the tramsmit speed would actually stay the same, i really cant see it dropping just because you have connected 4 computers to it .unless it just had one port and there was 4 wireless cards.

    Im not sure if that made sense, but im going looking on belkins site for you now
     
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  5. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    All the stations share the overall speed. If only one is talking to the AP, and the others are silent then that one is going at full speed. If two are talking at the same time then they only get half speed.

    Exactly the same thing happens on Ethernet, so you shouldn't be surprised by this!

    Harry.
     
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  6. Boycie
    Honorary Member

    Boycie Senior Beer Tester

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    I was half thinking of the hub *switching* in some way to maximise the bandwidth.... :oops:
     
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  7. zxspectrum

    zxspectrum Gigabyte Poster Premium Member

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    I was also thinking that the only thing that would be sacrificed was the actual broadband speed and not the rate of the transfer speed. As the one we have does have 4 ports on it.
     
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  8. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    The difference here is that a hub-switch switches between different physical media, so can improve throughput, whereas the AP only has one physical media - the channel bandwidth!

    :biggrin

    Harry.
     
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  9. Boycie
    Honorary Member

    Boycie Senior Beer Tester

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    ah, i see! Thanks for another explanation :clap
     
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  10. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Broadband is the same. If only one of you is using it at one time then that person should get full bandwidth (contention and 'fatpipe' permitting). If two of you are using it at the same time then you would normaly each get half speed.

    Harry.
     
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  11. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    Interesting answers here. Obviously I know that you don't actually get 54mbps. Thanks Harry and everyone.

    One thing I'm not clear on, what did you mean by this Harry?
    Do you mean with if a PC is transmitting and receiving at the same time? In this case, I fully understand that. Or do you mean when two clients are communicating via a switch? In which case, I understood modern switches run at 100mbps (or whatever speed they are) on each port.

    [EDIT]I think you just answered my question while I was typing it!
     
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  12. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    OK - I'll expand a bit on that.

    Assume a large network where the machines are connected by a *hub*. All packets from all machines go to all machines.

    If just one machine is sending a file to a second machine then it will see the full bandwidth - say 100Mbps. When another pair starts up doing the same then the speed for each pair will be halved so they share the network equaly.

    A hub-switch makes great improvements on this by directing packets only over the links that need it. This means that instead of one network of 100Mbps you now have many networks each of 100Mbps.

    As long as the hub-switch has the capacity it can keep lots of these streams going at once, as long as any given machine isn't trying to talk to two others at once. If it does then that machine will see half speed on its local piece of network.

    Harry.
     
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  13. zxspectrum

    zxspectrum Gigabyte Poster Premium Member

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    I enjoyed that thread, i hope your all going to be this helpful when i start getting stuck in my UNI stuff lol
     
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  14. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Depends on what you read at Uni! :biggrin

    Harry.
     
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  15. slyuen

    slyuen Byte Poster

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    if this is true, how come I can't even check my e-mails when my housemate is streaming video/downloading stuffs...

    The Wifi router is closer to me than him.... I don't even get 10% of bandwidth when he is doing that... :(
     
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  16. Mr.Cheeks

    Mr.Cheeks 1st ever Gold Member! Gold Member

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    are you sure he has not restricted your bandwidth?
     
  17. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    You should be able to - even if very slowly.

    However - in the real world some routers are not very good at allocating bandwidth. In addition there may be traffic shaping happening at your ISP that favours streaming, either by design or by accident.

    You need a fair amount of analysis to discover what is happening here.

    Harry.
     
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  18. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    Some WAPs have a QoS (Quality of Service) option that gives priority to bandwidth dependant traffic such as media files. You could have a look at the WAPs configuration to see if you have this enabled.
     
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  19. Baba O'Riley

    Baba O'Riley Gigabyte Poster

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    PS. Thanks for the expansion Harry, that what I thought. :thumbleft
     
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  20. michael78

    michael78 Terabyte Poster

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    I didn't know that. It's a good question and one that I've never thought of. I knew there was a lot of overhead with encryption etc but thats a lot if it takes nearly have the bandwidth up...:blink
     
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