A Basic Understanding of Wireless Standards & How Wi-Fi Works...
- Wireless Standards
There are many different types of Wi-Fi Standards in use, I refer to Protocols 802.11A, 802.11B, 802.11G, 802.11N, 802.11AC and now 802.11AD (arriving in 2014) , We usually refer to these as Wireless-G, Wireless-N or Wireless-AC, currently the most popular protocols in use are Wireless-G (upto 54Mbps) and Wireless-N (upto 150Mbps in 20Mhz mode or upto 270/300Mbps in 40Mhz mode, if router and devices support this mode), most of these protocols use the 2.4Ghz Radio band, there are also now Dual-Band routers which use 2.4Ghz and 5Ghz and soon there will be Tri-Band in 802.11AD.
Using the 2.4Ghz Spectrum & Wireless G & N as an example (as these are the most common protocols in use today) your router broadcasts over the range of 2.4Ghz (2,400Mhz) to 2.4835Ghz (2,483Mhz), each channel is 20Mhz Wide (or 40Mhz wide in upto 270/300Mbps mode) and each channel is spaced 5Mhz apart, because each channel is a quarter the width of the entire band it means channels over-lap each other (which can cause problems with multiple neighbouring networks in range of each other), for 'G' and 'N' networks there are actually FOUR non-overlapping channels (as opposed to people usually thinking they are just three) - these are 1, 5, 9 and 13 - the advice of using channels 1, 6 and 11 came from older Wireless 'B' technology as the channels on that protocol are 22Mhz wide. There are only TWO non-overlapping channels in 40Mhz mode as each channel uses half of the entire spectrum to get speeds upto 300Mbps.
Credit: Liebeskind, Wikipedia:
The most common form of Wireless Interference is neighbouring networks affecting each other, but interference can come from other sources from around your home, these are usually other radio devices that use the same 2.4Ghz range such as DECT phones, Baby Monitors, AV Senders, Wireless Door Bells, Wireless Thermostats, other things such as Halogen bulbs, Dimmer Switches and Microwave ovens can give off interference that can affect it, also faulty electrical devices nearby could be emitting RFI (Radio Frequency Interference) or EMI (Electro-Magnetic Interference) that might be affecting it, the only way of being able to find out is by turning all devices off then turn on 1 by 1 and test you wifi until you find the culprit.
How to Improve your Wireless Range...
- Checking Neighbourhood Congestion & Changing Channels
The first thing one can do to try and improve reception issues is to monitor your neighbourhood's wireless spectrum usage to see what channels are being used so you can move your broadcast into a less congested part of the spectrum, the best way to do this is to download a program called inSSIDer (in my signature below or google it), install and launch the program, click the start button so it starts monitoring (if it doesnt start automatically) then click the 2.4Ghz Tab, remember the lower the number (such as -45dBm) the stronger the signal, it will show on the 2.4Ghz Tab as higher in the chart.
Now using the program you should be able to see yours and your neighbours wireless networks, the channels they are using and their signal strength.
If your channel is over-lapping any of your neighbours and you can see un-used spectrum then change your channel to suit, e.g. if your neighbours are using channels 1 and 11 then you use 6, if your neighbours are using the entire spectrum then your best bet is to match the channel that has the weakest signals on it, try to avoid overlapping multiple networks as this can really cause you problems, you should be free of neighbouring channels OR over-lapping or sitting over just 1 channel, never sit between 2 neighbouring networks where your signal over-laps both as your router and devices will be waiting for traffic from both and thus slowing you down further.
If your neighbourhood is totally congested with several or more networks and is having an impact on performance then you can upgrade to a 5Ghz router...BUT...all your devices must also be upgraded to 5Ghz and this would only be possible with PC's and Laptops... mobile phones would not be able to use 5Ghz (unless supported), most 'Dual-Band' routers will operate both bands at once so those devices that dont support 5Ghz can use the 2.4ghz Radio and those that do support 5Ghz can use the 5Ghz Radio.
If your neighbourhood is completely or almost un-used but only by you, then try the free channels and monitor the signal strength in inSSIDer, e.g. I find the strength is better on channel 11 than 6 (both are available) - this means that around that range (channel 6) there could be some interference from other sources.
- Router Location and Orientation
Another way to help boost signal range is your routers location and its orientation, Ideally your router would be situated central to where all your devices are that use it, this gives all your devices a good share of signal strength, if you have your router in one corner of the home then those near it will have good reception and those at other end of home will have poorer reception. Most routers today have internal Antennas, these antennas are in a fixed position and in routers that sit flat means they are usually pointing off horizontally, if you have a router sitting flat you may find your signal improve quite a bit if you stand it up - you can also turn it 90 degrees one way, then another and see if signal gets any better again, one can monitor inSSIDer whilst making these changes, of all flat lying routers I have tested the signal strength greatly improved once the router was stood up on its side, turning changes the orientation of the broadcast signal, basically your signal is bouncing off walls aswell as going through them so turning the router can strengthen (or weaken) a signal....try it and see. Always try too keep your router free up on its own away from other electrical devices (see interference above).
- Wireless Extenders/Repeaters and Powerline Adapters (Homeplug Adapters)
If your home is so large and your current router just cant cope then what you can do is purchase a Wireless Extender or Wireless Repeater, this basically sits on the fringes of the reception of the main router and picks up the signal and re-broadcasts it, this allows you to double your range instantly. Another option is to be rid of Wi-Fi altogether and use Powerline Adapters (Homeplug Adapters), especially if your devices are in a fixed location (such as PC's or STB's) these plug into your power sockets on your wall, one at router and one at PC and LAN cable from from each to each Adapter, your network is then broadcast over your internal electric wiring, not only does this remove the whole neighbouring interference problem but it is also more secure.
Thats all I can think of for now...if anyone else has anything too add please do