Apple TV Peer-to-Peer using WiFi channels 6 and 149

By George Stafanick, Blog Contributor
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Introduced in iOS 7.1, peer-to-peer AirPlay uses BTLE for a discovery process. No longer is a network infrastructure required for discovery and even direct communication.

From Apple:

iOS 8 supports the ability to stream content from an iOS device to Apple TV even if the devices are on different networks or there's no network available. The iOS device uses Bluetooth Low Energy (BTLE) to begin the discovery process of available Apple TV devices and then establishes a connection directly to Apple TV using Wi-Fi.

In iOS 8, peer-to-peer AirPlay lets a user use AirPlay directly from a supported iOS device or Mac to an Apple TV without first connecting to the infrastructure network. Peer-to-peer AirPlay eliminates the need to join the right network or disclose Wi-Fi passwords, avoids reachability issues in complex network environments, and provides a direct path from the AirPlay sender to AirPlay receiver to optimize performance. Peer-to-peer AirPlay is enabled by default in iOS 8 and Mac OS X Yosemite v/10.10, and doesn't require any user configuration.

This is where it gets interesting

Peer-to-Peer discovery is initiated using Bluetooth Low Energy (BTLE) when a user selects AirPlay on an iOS 8 or OS X Yosemite v/10.10 device. This causes the device and the Apple TV to visit Wi-Fi channel 149 in the 5 GHz band and Wi-Fi channel 6 in the 2.4 GHz band, where the discovery process continues. Once the user selects an Apple TV and AirPlay starts, the Wi-Fi radios timeshare between channel 149 and whichever infrastructure channel each device is currently using. If possible, the AirPlay sender roams to the same infrastructure channel the Apple TV is using. If neither device is currently using an infrastructure network, the devices will utilize Wi-Fi channel 149 only for AirPlay. Peer-to-peer mirroring adheres to 802.11 standards, sharing Wi-Fi bandwidth with other Wi-Fi devices.

Apple's play on deployment 

When you deploy Apple TVs on a large enterprise Wi-Fi network, consider the following guidelines:

Connect Apple TVs to Ethernet whenever possible

Don't use Wi-Fi Channel 149 or 153 for your infrastructure network

Don't place or mount the Apple TV behind objects that could disrupt the Bluetooth Low Energy and Wi-Fi signals

Wirelesssguru's take:

While I don't consider Apple TV as an enterprise grade solution. One advantage of Apple TV in the enterprise is wireless screen sharing. It's an inexpensive solution and easy to deploy, once all the network gymnastics are worked out with bonjour. This BTLE feature can allow guest or contractors screen sharing without compromising wireless network security.

Apple points out WiFi channels are used as part of the discovery and adhoc connection. As a WiFi engineer, when deploying these solutions, we need to be aware and address any channel concerns. A study of channel duty and behavior should be validated before deployment. Im glad Apple is leveraging the 5 GHz spectrum for adhoc streaming. But Im also concerned about the behavior in the comment " Once the user selects an Apple TV and AirPlay starts, the Wi-Fi radios timeshare between channel 149 and whichever infrastructure channel each device is currently using". 

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