The last Sniff Wi-Fi post; on why Wi-Fi professionals should stop disabling low data rates, was met some resistance. Be it in the comments or on Twitter, several experienced Wi-Fi folks disagreed. All arguments in favor of disabling low rates (the ones that were presented to me, at least) were refuted in the text of the Leave, Leave, Leave My Rates Alone blog post. But text is a less accessible messaging method. "A picture is worth a thousand words", as the old saying goes. If pictures will get the message across better, then pictures are what I'll use. What follows is an illustrated look at why disabling low data rates is a bad idea.
It's gauche to begin an illustrated work with text, but to understand the problem with disabling low Wi-Fi data rates one must first accept some facts about Wi-Fi devices (smartphones, laptops, etc.):
1. Wi-Fi devices -- not APs -- control associations and roaming.
2. Wi-Fi devices roam based on low received signal strength (RSSI) -- …
In some circles, Apple Wi-Fi devices are knows to have problems with lost connections. iPhones and iPads will unexpectedly miss incoming calls, have delays in receiving push notifications and even be forced to reauthenticate. There is a solution to Apple devices' connection problems, and as with most "device problems", the fix resides on the infrastructure. The DTIM setting needs to be increased. (Apple recommends a setting of 3 or higher.) Here's why:
Some Apple Wi-Fi connection problems stem from Apple iOS devices' use of 802.11 power management. To understand what Apple devices are doing with power management, one must first understand how 802.11 power management works.
Let's start with unicast data. The 802.11 standard allows devices' Wi-Fi radios to enter the Doze state in order to conserve battery life. Wi-Fi radios in the Doze state are unable to receive data from the AP, so APs buffer all unicast data that has a destination MAC address of a…
Two years ago tomorrow Apple introduced the iPhone 5. It was a big deal. It was a big deal for gadget folks who wanted a bigger iPhone. It was a big deal for wireless LAN folks who wanted users to use smartphones with speedier WiFi. Now the iPhone 6 has been announced and it appears to be more of the same. Gadgeteers get their bigger iPhone. Wireless folks get their faster speeds. Problem is, the faster wireless speeds likely won't mean anything for high capacity wireless deployments.
The big news about the iPhone 6 is 802.11ac. Yippee! Apple has finally adopted the latest and greatest WiFi standard in a mobile device.
802.11ac has data rates as high as 6.9 Gbps in the standard, but wireless LAN folks know that's not what happens in real life. Real 802.11ac devices top out at a 1.3 Gbps data rate when multiple input-multiple output (MIMO) antenna systems are supported, while non-MIMO devices top out at 433 Mbps.
The iPhone 6 and iPhone 6 Plus are non-MIMO 802.11ac d…