The 802.11ax OFDMA channel consists of 256 sub-carriers. the sub-carrriers can be grouped together into smaller sub-channels known as Resource Units (RUs). Depending on the channel bandwidth and the number of clients connected, the Resource Units can be as small as a 26 sub-carrier resource unit in a 20 MHz channel with 9 Clients or […]

As seen in the introduction for 802.11ax (here), the major change that was introduced in 802.11ax (WiFi 6) was the introduction of multi-user transmission in a single transmit frame and OFDMA. Some of the other major changes in PHY as related to the previous generation WiFi 5 are tabulated below 802.11ac (WiFi 6) 802.11ax (Wifi […]

The next evolution of the WLAN standard after 802.11ac is the 802.11ax standard. In the meantime WiFi Org has adopted a new nomenclature of naming different standards by a WIFI number. Hence, 802.11ac became WiFi 5 and 802.11ax is termed WiFi 6. WiFi 6 includes the 2.4 GHz and 5 GHz band operation. A new […]

Some Vendors such as Cisco extend the PMKID key caching mechanism to pro-actively cache the keys in a WiFi BSS network. This mechanism is also termed as proactive or opportunistic PMKID caching. As a refresher, The PMKID Key caching as seen in the article <PMKID Key Caching> is to cache the Pairwise Master Key ID […]

PMKID stands for Pairwise Master Key Identifier. It is a unique identifier that is generated during PMK security association for a specific AP-Client. The PMKID computation is basically a truncate-128 operation on HMAC-SHA-1/HMAC-SHA-256/HMAC-SHA-384 hashing. The different ways of obtaining PMKID depends on the cipher suite selected for RSN. Refer section “12.7.1.3 Pairwise key hierarchy” in […]