The major change was around the implementation of the 40MHz channel. It has been adjusted to accommodate older 2.4GHz band devices, which may be confused by the wider channel bandwidth.

The new spec calls for the use of two 20MHz bands. Under version 2.0, the system will scan the environment looking for legacy devices that might not understand the wider bandwidth, in which case the 802.11n device will back off and send data over only a single 20GHz band. While this would slow down overall data throughput to a single 20MHz channel, 802.11n's MIMO (Multimedia In Multimedia Out) technology will still give 802.11n faster performance.

A second change will allow an 802.11n device to check to make sure both channels are clear before sending data. A third change allows devices, such as Bluetooth-enabled devices, to send a signal saying it does not want to receive data in the 40MHz mode.

In order for a Bluetooth device to send this alert, it must also include wireless LAN, which, for example, the Apple iPhone includes.

Wireless LAN IEEE 802.11a devices in the 5GHz band will be able to use the full 40MHz channel.