4802.11n Interface

4.1. MAC layer evolution

Table 4.1 summarizes the features provided by the MAC (Medium Access Control) layer.

Table 4.1. Features of MAC layer

Features Mandatory/optional Description
Reception A-MPDU Mandatory MAC frame aggregation
Transmission A-MPDU Optional
Reception A-MSDU Mandatory Aggregation of MAC frame payload
Transmission A-MSDU Optional
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

4.1.1. Management frames HT Capabilities information element

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

Information Designation
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

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