This subsystem samples the input modTypeIndex and codeRateIndex values along with the first valid input sample. The subsystem also generates a ready output signal that is used for external interfacing. The Frame Controller and Input Sampler subsystem generates control signals for later stages of the model. The OFDM modulated signal is filtered with a passband frequency of 1.4 MHz and sent out as transmitter output. Data stored in the RAM is read out and modulated by the OFDM Modulator block. The RAM holds these signals for a duration of one frame. These five signals are multiplexed based on their valid signals and stored in a RAM. Individual stages in the Header and Data chains are explained in further sections. This data is processed through multiple stages in the Data chain. Payload data is provided as an input to the transmitter. These header bits are processed through the Header chain as shown in the figure. Header bits are formed based on the input modulation type and code rate values. Header and Data vary based on the inputs given to the transmitter. They are stored in separate look up tables (LUT) and accessed whenever required. SS, RS, and Pilots are same for every frame. There are five different signals that form the OFDM frame: SS, RS, Header, Pilots, and Data. The following figure shows the high-level architecture of the OFDM transmitter.

Ofdm simulink