For future broadband telecommunication systems and networks based on OFDM technology, efficient implementation of an OFDM modems is a major requirement. In this paper, we are going to present some fundamental aspects of implementation of an OFDM based wireless MAN modem on TI Digital Signal Processors (DSP) C6000 family. To this purpose, we model a typical MMDS system based on IEEE802.16a standard, and simulate it in TI Code Composer Studio™ (CCS) environment with C programming language and compare the floating and fixed point implementation aspects of the system. This is useful and enhances rapid prototyping of a DSP based wireless MAN modems. The wireless MAN system will be demonstrated a high speed wireless communication system. One basic component of common OFDM systems is the computation of the DFT and IDFT which was our main focus in this paper via considering some efficient FFT algorithms like the Radix-2 and the Radix-4. In the next part, we compare various methods of implementing of a simple channel estimation and equalization for compensation of the signal affected by frequency selective fading channel model which were employed in our simulation.