Table 4.1 summarizes the features provided by the MAC (Medium Access Control) layer.
Table 4.1. Features of MAC layer
|Reception A-MPDU||Mandatory||MAC frame aggregation|
|Reception A-MSDU||Mandatory||Aggregation of MAC frame payload|
|Block Ack||Mandatory||Acknowledgment for a block of MAC frames|
|Protection||Mandatory||Detection of radio channel occupancy time by non-802.11n compatible stations|
|RIFS||Mandatory||Reduced inter-frame interval|
|Spatial Multiplexing Power Save||Mandatory||Power save by reducing the number of spatial flows|
|Power Save Multi-Poll||Optional||Power save by modifying the radio access procedure for smaller frames|
|Non–TKIP||Mandatory||TKIP is no longer allowed|
|Phased Coexistence Operation||Optional||Alternating radio channels at 20 and 40 MHz|
The management frames indicate that the access point has an 802.11n interface by including the HT (High Throughput) Capabilities information element.
The information provided by the HT Capabilities Info field is described in Table 4.2.
Table 4.2. Information of HT Capabilities Info field
|LDPC Coding Capability||LDPC error correction code|
|Supported Channel Width Set||Bandwidth of the radio channel (20 MHz / 40 MHz)|
|SM Power Save||Power save for spatial multiplexing|