Physical Layer (PHY) processing

Scrambler: It is nothing but a randomizer, which randomizes incoming data stream of continuos 0's and 1's. This helps in AGC and timing recovery circuit

Channel Encoder: Its a FEC scheme, which adds extra redundent bits to data in order to increase the error correcting capabilities. Convolution codes (CC) and Convolution Turbo Codes (CTC) are example of channel encoder.

Interleaver: Protect burst errors by spreading incoming bits in different channels, which helps in recovering data even after burst errors. It ensures that adjacent code bits are mapped to non adjacent subcarrers, which provides frequency diversity and improves the performence of decoder

Symbol Mapper: The sequence of binary bits are converted into sequence of complex valued symbols. QPSK, 16QAM and 64QAM are defined in WiMax

Space Time Coding: A space–time code (STC) is a method employed to improve the reliability of data transmissionn in wireless communication systems using multiple transmit antennas. STCs rely on transmitting multiple, redundant copies of a data stream to the receiver in the hope that at least some of them may survive the physical path between transmission and reception in a good enough state to allow reliable decoding

Subcarrer Mapping/IFFT: Depending on the type of subcarrer allocation scheme data will be mapped on the different subcarrers. There are basicaly 2 different types of schemes: Adjacent subcarrer permutation and distrubuted subcarrer permutation scheme. For 1024 FFT (subcarrers) 768 subcarrers are used for data, 82 for pilot and rest are unused. IFFT converts frequency domain signal to time domain and maps data to no of IFFT subcarrers.

D/A: Digital to Analog converter converts digital data to analog for the transmission on the air.

RF Card: Analog data will be modulated with the 2.3 Ghz range of frequency (depending on the system freq), power amplified and will be feed to antenna through TDD switch.