I am sure almost all of you have been frustrated with your wifi. At some point you get fed up and decide it is time to upgrade. You read the reviews. Look on Amazon for buyer reviews. You finally narrow down your choice. You choice is most likely an AP with more power, longer range, and higher speeds. This new AP will have the power to blast the wifi signal to all your mobile devices.
But almost all of you will make the transition and shortly discover things are not that much better.
Why? Because as Arstechnica points out almost everyone identifies the problem incorrectly.
“Drowning out the neighbors’ Wi-Fi
Let’s be honest here: an awful lot of us, me included, are pretty much fine with the idea of “drowning out the neighbors” Wi-Fi with a higher powered router of our own. We’re right back to that instinctual model of a conversation: the signal from the neighbors’ Wi-Fi is pretty weak; if ours is strong enough, we can drown it out, and if that makes a problem for them they can either suck it up or go get a higher-powered router of their own, right?
This is a very human approach, but it’s not a very effective one. Consider a conversation at a crowded bar: you’re really intent on what your friend or date is saying, but the two of you are competing with the conversations on either side of you and behind you, as well as the music playing. So, naturally, you speak up! Unfortunately, what happens then is the people all around you get louder, too, resulting in a zero-sum game which ends up with everybody yelling and nobody able to understand anything very well.
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The problem is 2.4ghz is crowded and more power does not improve things. This is a digital issue there are too many bits trying to get on the 2.4ghz channels. So move to 5ghz by turning off 2.4ghz. Unfortunately leaving both radios on is going to too many times leave you with the 2.4ghz collision problem.
“Wireless networking doesn’t work that way. It’s engineered, not instinctual, and so the standard directly prevents devices “shouting over” one another. Instead of having a crowded-bar-style competition for bandwidth, each device must wait for a chance to “speak,” clearly and without competition from other devices. In technical terms, a Wi-Fi network is a collision domain, and this enforced politeness helps avoid packet collision. This is well worth doing, because if packets do collide, each device then has to stop transmitting, wait a random interval of time, then try again—thereby, hopefully letting one machine start “talking” enough before the other that they don’t drown one another out again. (If they picked the same random number, then they’ll collide again and have to start the whole process over again.)
Most technical people understand this about their own networks, but many don’t realize that it’s not just your Wi-Fi devices that are all on a single collision domain—it’s all Wi-Fi devices on the same channel. Any, repeat, any transmission on the same channel ties up that channel, even if it’s on a different network with a different SSID and different WPA key. The 802.11 wireless network specification uses Clear Channel Assessment to determine whether the channel is “busy” or not, and if CCA says “occupied,” the wireless device has to wait its turn. If your laptop, phone, or tablet can “hear” the preamble of another 802.11 transmission at -82 dBM, whether it’s on your network or not, it has to sit tight, shut up, and wait its turn to speak.
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