802.11n Protection Mechanisms: Part 1
When 802.11g was introduced, we had RTS/CTS and CTS-to-Self protection mechanisms. What do we get with 802.11n so that it's backwards compatible with 802.11a and 802.1b/g? First, there's a couple of new things I'd like to introduce, and then we'll get to the protection rules.
In an ERP Beacon, ERP stations look at the "ERP Information Element" to determine whether or not protection is necessary in the BSS. See my whitepaper here:
http://www.cwnp.com/learning_center/search_details.php?doc_id=l7w2 for further information.
In an HT Beacon, HT stations use the "Operating Mode" and "Non-greenfield STAs Present" fields in the HT Information Element to determine whether or not to use protection.