4 Wi-Fi Tips from Former Apple Wi-Fi Engineer

Question

Hi,  I thought this was a real neat little article from Alf Watt, former Apple Wi-Fi engineer and creator of the fantastic Wi-Fi utility, iStumbler,  Thought I would share.
Alf Watt, former Apple Wi-Fi engineer and creator of the fantastic Wi-Fi utility, iStumbler, joined us on this week's Mac Geek Gab 509 to talk all things Wi-Fi. The episode contains a bunch of juicy Wi-Fi tips and I highly recommend you give it a listen, but for now our four favorite tips are listed below. Think of this as the MGG 509 Cliff's Notes... and make sure you read, erm, listen to the whole thing, too. On to the tips:
1. Use same SSID for all radios on the same network (be they 2.4GHz or 5GHz). If you have one network in your home but have either multiple routers/access points for better coverage or multiple radios in one access point, the advice is the same: use the same SSID (wireless network name) for all of them and let the client devices each decide which is best to use.
Apple devices choose networks by your preferred order. Period. If you have multiple networks of different names your Mac or iPhone will always choose the first in your iCloud-synced "Preferred Networks" list even if this one isn't going to give you the best bandwidth. If you have the network name/SSID the same then it will chose the radio that it predicts will give the best throughput (which isn't always the one with the best signal, but that's an even geekier discussion you can hear in the show). Make all the Wi-Fi networks in your home the same. Your life will be better for it.
2. Deal with congestion with more access points using less power. In response to a listener's query about how best to deal with having lots of access points in a small location, say an apartment building, the best thing to do is to actually increase the number of access points but lower the transmit power on each so as to keep them from interfering with each other. It's good if your neighbors do this, too, of course, but it will help even if it's just you. We recommend using Powerline adapters to connect all of your access points together to avoid the headaches of just extending Wi-Fi.
Another helpful option is to use 5Ghz channels where possible. The higher frequency band doesn't go through walls as well and may be exactly what the Wi-Fi doctor ordered in highly-congested areas (and when we get 60Ghz Wi-Fi, that'll be even more helpful!)
Next: When to use Wide channels and Antenna Orientation.
3. Don't use "Wide" 40MHz channels on 2.4GHz. Some routers (not Apple's) will allow you to use "Wide" channels on the 2.4GHz band. The problem is this band is so congested that you'll likely just wind up making things worse instead of better. Bluetooth lives here, too, and will appreciate the breathing room. Plus, Apple made the decision years ago to not support these wide channels at 2.4GHz, so even if your router allows you to enable it your iPhone and MacBook won't use it.
On your 5GHz radios 40MHz channels are perfectly acceptable (again, your Apple router takes care of this for you). And with 802.11ac (5GHz only) you may wind up using 80MHz or even 160MHz channels. Just remember that current 5GHz implementations only have enough room for TWO (yes, 2) 160MHz channels, so choose wisely. The good news is that current 802.11ac routers use "cognitive radio" technology. This means they listen before they talk and that will ratchet down from 80MHz (or 160MHz) to something lower if they see another router communicating in the same band. Smart.
4. Be smart about antenna orientation. If your router has internal antennas (as most new models do), make sure to use them in their natural orientation. Put simply: if the router has feet, use them as feet (as opposed to laying it on its side). Some routers have feet on two sides and give you placement options, so feel free to capitalize upon this flexibility.
For routers with those adjustable, "rubber ducky" antennas, Alf recommends pointing one straight up and one flat out. This is because radio reception is maximized when both client and access point have matched polarization (antennas pointing along the same plane).
Some client devices have antennas in vertical orientation, some horizontal. The current crop of MacBooks, for example, have their antennas in the black plastic part of the hinge in a horizontal orientation.
Those tips should get you started. Give Mac Geek Gab 509 a listen to learn more about beamforming, the future of Wi-Fi, how your router decides what country it's in (and what channels it can use!), the future of iStumbler (and other products from Alf) ... and more!
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Answer 1

Roaming isn't part of the WiFi specification.
While some clients may look for the strongest signal most just look to see if they can connect to the last AP they were connected to.
Some SOHO APs will allow you to set them to reject a connection  weaker than -70db.
To get efficient roaming between APs you need commercial AP controllers which monitor the entire network of APs to see which one offers the strongest signal and has the smallest load.
To the best of my knowledge there are no SOHO router/APs that talk to each other which is necessary for effective and seamless roaming.   Apple hardware is supposedly better than other brands, but I have never used it.
Most people are better off setting up individual SSIDs for each radio that identifies the location (Upstairs 5,  Upstairs 2.4, etc.) so a user can make an intelligent choice of which to connect to.   If speed doesn't matter such as when checking and downloading e-mail then any SSID/radio will do.   If you want to stream video than the nearest and probably the strongest 5 Ghz AP is what they should connect to.
Changing the names of SSIDs is trivial so if people want to try using all radios with the same SSID they should go for it.  If they aren't happy with the results then go to plan B and rename.