Forums › LAN (ethernet/Wifi/routers/Bluetooth) › Boosting Wireless Coverage - Help

phil1066

38 posts

Geek

#23657 5-Jul-2008 21:08

Someone I know flats above a large out-house garage (timber construction) next to the owners house. They have wireless and I have recently bought a usb wireless adaptor for the PC above the garage. Unforunately the signal from the house appears to be too weak to be detected. What are my options?

So far I have figured out (to stay wireless) I can:

1. Buy a high gain antenna for the owner to use or extend their output. Do I need 5dbi, 7dbi or 8dbi? (ive been looking at Trademe items).

2. But a wireless signal booster box like d-link offers.

At this stage becuase I know nothing about their network Im thinking 'cheap' option to start with.

Any views or assistance greatfully accepted :-)

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#143283 5-Jul-2008 21:31

This should help you ...

nzkc

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#143284 5-Jul-2008 21:33

For a low tech, low cost option you could try something from here: http://www.usbwifi.orconhosting.net.nz/

iainw

75 posts

Master Geek

#150676 23-Jul-2008 15:35

Option 1 is not a particularly good/cheap option.

Remember that 802.11 is a two way standard. For every data packet sent, an Acknowledgement must be recieved. Unless you have a specialist PCMCIA card, your access point has a significantly stronger radio than your USB adapter. Boosting the Access Point signal through a high gain antenna, will have no benefit if the USB dongle can't produce a strong enough signal to talk back to the access point.

phil1066

38 posts

Geek

#150709 23-Jul-2008 17:46

okay now Im confused, was planning to get an aerial this week. surely if the usb adapter can detect the signal it can connect with it?

iainw

75 posts

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#150864 24-Jul-2008 09:51

Not necessarily...

Unfortunately RF is not very black and white.

USB dongles typically have very weak radios, fairly low gain antennas, and fairly high RSSI thresholds (ability to 'hear' weak RF signals). You can create a similar sort of scenario as a lot of early satellite connections, where you can recieve, but not transmit.

The other consideration, is that high gain antennas, do not amplify the signal at all. They simply refocus the energy to a more concentrated beam - much like a torch does. If you get a 5dBi or 7dBi antenna, you increase coverage in one area, by decreasing coverage in another area. Just knowing the gain of the antenna isn't enough. You can focus your coverage vertically or horizontally, either of which may give YOU coverage, but could do so at the expense of the house owner.

Possibly your best/cheapest option is to purchase a wireless repeater (not booster), depending on the physical geography. Ideally, you install it half way between the original AP, and your client, it hears the signal, and then rebroadcasts the packets verbatim.

While there are better solutions, they will all cost notably more.

phil1066

38 posts

Geek

#150878 24-Jul-2008 10:21

thanks - where do I find wireless repeaters?

HP

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iainw

75 posts

Master Geek

#150884 24-Jul-2008 10:29

http://www.gowifi.co.nz/products/vmchk/access-points-802.11.html

phil1066

38 posts

Geek

#150912 24-Jul-2008 12:11

thanks - is one of these an option as a repeater

D-Link DWL-900AP+ AirPlus Enhanced 2.4GHz Wireless

iainw

75 posts

Master Geek

#150919 24-Jul-2008 12:21

Don't know first hand to be honest.

From a technical point of view, a repeater, a bridge, an Access Point are all exactly the same thing. Manufacturers simply write firmware that limits the ways in which you can use the device so they can sell more product.

All Access Points have a minimum of 1 x 802.11(wireless) interface, 1 x 802.3 (Ethernet) interface.
Bridge and Access Point are exactly the same - they bridge 802.3 packets to 802.11 packets and vice versa. Repeater is slightly different, in that it recieves an 802.11 packet, and then re-broadcasts it on the same interface.

If the dLink (or any other) product can't act as a repeater, it is because dLink (or other manufacturer) doesn't want you to, not because the capabilities aren't there.

You may want to consider a repeater that is sealed for outdoor use depending on where you are able to install it. Netcomm has one, so does EnGenius.

bleater

58 posts

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#151346 25-Jul-2008 16:13

iainw:
The other consideration, is that high gain antennas, do not amplify the signal at all. They simply refocus the energy to a more concentrated beam - much like a torch does. If you get a 5dBi or 7dBi antenna, you increase coverage in one area, by decreasing coverage in another area. Just knowing the gain of the antenna isn't enough. You can focus your coverage vertically or horizontally, either of which may give YOU coverage, but could do so at the expense of the house owner.

Incorrect. A tuned impedence-matched antenna will allow the radio to transmit at greater power at the tuned frequency, as well as giving a more focussed beam shape.

FWIW, the cheapest approach is to get a long USB cable (get one with an active booster if you're going over 10 metres) and put the USB dongle on the end. Then it doesn't have to connected right at the back of the PC, and you could (e.g.) run the cable so that the USB dongle is much better positioned to get a good signal from the main building.

iainw

75 posts

Master Geek

#151362 25-Jul-2008 16:41

bleater:
iainw:
The other consideration, is that high gain antennas, do not amplify the signal at all. They simply refocus the energy to a more concentrated beam - much like a torch does. If you get a 5dBi or 7dBi antenna, you increase coverage in one area, by decreasing coverage in another area. Just knowing the gain of the antenna isn't enough. You can focus your coverage vertically or horizontally, either of which may give YOU coverage, but could do so at the expense of the house owner.

Incorrect. A tuned impedence-matched antenna will allow the radio to transmit at greater power at the tuned frequency, as well as giving a more focussed beam shape.

FWIW, the cheapest approach is to get a long USB cable (get one with an active booster if you're going over 10 metres) and put the USB dongle on the end. Then it doesn't have to connected right at the back of the PC, and you could (e.g.) run the cable so that the USB dongle is much better positioned to get a good signal from the main building.

Actually its not incorrect - it is just more technically accurate than most people care about. The antenna is not part of the radio, and once the energy reaches the antenna, all you can do is redirect it, not amplify it.

An antenna is a pasasive amplifier, in that it is not introducing any extra energy into the system. This is in contrast to an active amplifier, or more commonly - an amplifier, which has its own power source, and injects more energy into the system. All an antenna does is shape the overall energy into a narrower beam. You are not increasing the overall energy being radiated, you are simply sacrificing energy in one direction, to increase the energy available in another direction.

This is why simply saying "add a 5dBi antenna" is not really helpful. You need to know what you are giving up in coverage to increase the gain. A narrower elevation beamwidth is great if your clients are on a similar elevation to the antennas, however useless if you are upstairs and the AP is downstairs. You will get dramatically different performance from a 9dBi 35/35 antenna compared to a 9dBi 360/15 antenna.

Dyson

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bleater

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#151368 25-Jul-2008 16:49

OK, true, but most people think in terms of the whole system. The output power of most wifi ap's is limited by the antenna. If you put a high-gain antenna on the system, the radio can use higher power levels. It's the same with cellphones. So

it's semantics.

iainw

75 posts

Master Geek

#151369 25-Jul-2008 16:53

When you are dealing with RF, semantics can be the difference between a working network and some doorstops with pretty blinking lights.

phil1066

38 posts

Geek

#151990 28-Jul-2008 09:40

okay so I may try an aerial first then a repeater :-)

rphenix

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#154590 6-Aug-2008 10:56

In my experience (IANAE!)

forget those longer so called high gain antenna's they mostly dont work that well in my experience just a waste of $$ (unless you spend a heap and get the panel type) forget the omni directional ones.

Instead try this:

http://coachdanny.blogspot.com/2007/09/more-on-windsurfer-antenna.html (if you are lucky enough to have a usb wifi adapter with an aerial make two of these one for the wifi adapter one for the AP)

it costs nothing (bit of tinfoil really)and works suprisingly well. Of course you have two probelms getting signal from your access point, and getting signal back to the access point from your wireless card (which is usually where the problem is).

I recommend an 802.11N adapter even with an 802.11g AP they just seem to work way better with longer distances.

If the signal quality is really bad perhaps get a wireless ap that can act as wireless bridge I quite like the Uniden Buffalo routers (can be flashed with openwrt and have a built in amplifier) but then there are alot of mimo wireless N routers out now so a bit of research is warranted.

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