MAC Privacy Sublayer:
The MAC privacy sublayer provides authentication, secure key
exchange, and data encryption.
The physical sublayer is responsible for framing the MAC PDU
for transmission, media access, and slot allocation.
The 802.16 standard supports both Time Division Duplex (TDD)
and Frequency Division Duplex (FDD) operation. With the TDD
technique, the system transmits and receives within the same
channel, assigning time slices for transmit and receive mode.
The FDD technique requires two separate radio spectrums for the uplink and downlink channels.
WiMAX uses 256 carrier Orthogonal Frequency Division
Multiplexing (256 OFDM) for modulating data for transmission on
the radio carrier. Based on Frequency Division Multiplexing
(FDM), OFDM is technology that uses multiple frequencies to
simultaneously transmit multiple signals in parallel. Each signal
has a frequency range (subcarrier), which is then modulated by data.
WiMAX supports the following modulation techniques;