A good overview of 802.11n
1 posts by 1 authors in: Forums > CWNA - Enterprise Wi-Fi Admin
Last Post: July 19, 2007:
Last Post: July 19, 2007:
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I didn't make a list as I went, so I just now scanned through it really fast looking for stuff that stood out at me. Here's one:
The Aggregated MAC Service Data Unit (A-MSDU) mechanism increases the maximum size of the 802.11 MAC frames from the legacy 2304 bytes to 8k bytes. The Aggregated MAC Protocol Data Unit (A-MPDU) mechanism increases the maximum size of the 802.11 frames transported on the air link from the legacy 2304 bytes to 64k bytes.
2304 is the maximum MSDU size, not the maximum MPDU size (MAC frame size). The other two numbers are rounded-off. See below for quotes from the 802.11n-d2.0 draft.
The A-MPDU maximum length is 65535 octets.
Maximum A-MSDU length Indicates maximum A-MSDU length. See 9.7b (A-MSDU operation).
Set to 0 for 3839 octets
Set to 1 for 7935 octets
Here's another issue:
A-MPDU has increased the maximum size of the frames on the airlink from the legacy 2.3k to 64k bytes. A-MSDU has increased the maximum size of the frames transported between MAC and LLC from 2.3k to 8k bytes. Block ACK protocol improves efficiency by enabling back-to-back frame transmissions.
The maximum frame size transported between the MAC and LLC is still 2304 octets (bytes). Frames are aggregated into A-MPDUs (max = 65535 octets) and A-MSDUs (max = 7935 octets) at the MAC layer.
Hope this helps,
Devinator
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