Plug in repeaters and how they work...

Discussion in 'Networking & NAS' started by -=Rob=-, Aug 14, 2012.

  1. -=Rob=-

    -=Rob=-
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    Got a question over repeaters and wifi – I have a Virgin Superhub that is resident up stairs at the front of the house, this is because my PC equipment is all up there in the office where I work from. I have WiFi all over the house and it is pretty good, however in the conservatory it is not so good and sluggish as a result, in the garden it is not good at all.

    So I would like to get the WiFi better in the garden and conservatory and have looked into repeaters. I have found a curved type that plugs into a wall socket like this:
    300Mbps Universal Wi-Fi Range Extender : Wireless Range Extenders/Access Points : Maplin Electronics

    And this looks what it does I need it to do, however what I’m not sure is how repeating networks are configured and work, I think I uderstand readings the FAQ and other posts on here but wanted to get clarification... :)

    For example, I have mobile devices such as an iPad / iPhone that is connected to my superhub on and SSID, how does the device know to use the superhub when upstairs or the repeater when downstairs? Do they have separate SSID’s and I select or do they have same SSID’s and it’s intelligent. If someone could explain that would be great, and any comments on one of these plug devices appreciated if anyone has used one!

    Thanks…
     
  2. mickevh

    mickevh
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    Wi-fi repeating is generally a bad idea unless you cannot avoid it:

    Wi-fi repeaters work by listening out for and capturing each wi-fi transmission, waiting for the airwaves to go dead, then broadcasting a verbatim copy of the original transmission. That means your throughput will be at least halved as everything has to be sent twice, and those transmission cannot occur at the same time (in wi-fi only one thing at a time can transmit.)

    A much better way to deal with wi-fi coverage is to create a "cellular" infrastructure consisting of multiple wi-fi Access Points. This is the intent of the wi-fi designers - the "one AP covers the whole house" scenario we all have at home can be thought of as a special case where we can often "get away" with a single AP.

    The network of AP's then need to be connected together with a wired backhaul infrastructure of some kind. Ironicallly, installing all but the simplest "wireless" data network required the installation of a lot of "wired" infratructure. The "wireless" is only really for the "last hop" between the wired network infrastructure and the client device.

    I note that the device you link has the ability to run a "LAN" cable between it and you router, which would be the best option.

    In domestic environements, some people create the wired backhaul using HomePlugs to piggyback the data ontot the mains electricity supply. (see HomePlugs FAQ in this forum.)

    If you do use "repeating" then you won't need to worry about SSID's as all the traffic to/from the repeater will be exactly the same as that to/from your main AP (in your router) so you won't see separate SSID's.

    If you constuct the (much more preferable) "cellular" infrastructure (abeit one with only two cells in your case) then you can choose what to do about SSID's.

    You can either set separate SSID's in each AP and thus choose which one you connect to, however you'll have to swap (roam) your clients between them manually by disconnecting from one then connecting to the other.

    Alternatively, you can set up the same SSID's (and passphrase, security settings, etc.) in both AP's and your client devices may automatically roam between the two AP's without your intervention. Unfortunately, when/if to roam is a decision that isn't mandated by standards and it's in the gift of the client device designer as to how they make the determination as to when to roam. Note that it's the client device that makes the roaming decisions, not the AP's - so you really are in the hands of the client designers. Some may roam agressively, some may doggedly hang on to a working connection - there's good and bad arguments for either regime, Unfortunately, often as users we have little, if any, control over this.
     
    Last edited: Aug 14, 2012
  3. -=Rob=-

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    Thanks for the info Mick, appreciated - So from what I understand in your detail, the best option would be to utilise a hard wire to the router and then an access point from there. Because of the run between the preferred access point I'd have to utilise home plugs I think. I had actually considered the homeplug option but this wifi repeater device seemed to do what I wanted without the need, however I didnt realise that this would be the the detrament of the wifi speed!

    So to be clear, what I need to have is homeplugs, one at my router and one where I want to put the wireless access point. Then the access point is configured as such (not repeating) with either a seperate SSID or the same as my router and I rely on the dvice to be clever enough to link to the best signal one...

    I wish I could extend the range of the superhub itself, that may cure it and negate the need to do this! From what i read you cannot get high gain aerials or anything for them...
     
  4. -=Rob=-

    -=Rob=-
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    Last edited: Aug 15, 2012
  5. mickevh

    mickevh
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    That's pretty much it.

    I don't have HomePlugs (don't need them) but I believe you can get a "kit" which comprises one HP that connect to your router and a second HP that also has a wi-fi AP built in for the remote ends.

    You plug one HP into the mains near you router (don't forget to check you router has a spare ethernet port to connect to the HP) and a 2nd (3rd, 4th, etc.) where you want the improves wi-fi and thence set up it's SSID's etc as you desire.

    High gain antennas aren't a magic fix anyway. The laws of physics dictate that you can't counjure up energy out of thin air. High gains antenna just have a better "efficiency" rating compared to an "ideal" theoretically perfect antenna which converts all it's input enegy into radio waves.

    One understands that high gain antenna also tend to "flatten" the transmission pattern perpendicularly to the antenna and thus transmit more strongly "sideways" and reduce the transmissions along the antena axis (above/below it.) Depending on the area (in 3 dimensions) you are trying to cover, that may of may not be a bad thing. (Though I hasten to add I'm no RF engineer.)

    And even then, the laws that govern the radio output of wi-fi kit say something like you have to be within a certain output power along the strongest axis of the transmission pattern. Most wi-fi kit is already at of near the permitted legal max, so paradoxiacally switching to high gain antenna may mean you are actually required to lower you radio transmit power to remain within the law.

    Basically, "more signal from the AP" just isn't the universal omni-fix for all wi-fi ills. The best way to achieve great wi-fi coverage is to have multiple AP's, get them as close to your clients as you can and (ironically) turn transmit power down as low as you can get away with. At work I have a couple of hundred AP's, and I content myself that I have "enough" of then and have them close enough together when they start dialling down their transmit power (my AP's are rather clever gizmos that do this sort of thing automaticaly - you might not see that in SOHO kit.)
     
    Last edited: Aug 15, 2012

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