Performance evaluation of an OFDM-based LMDS using measured channel models

Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier system where data bits are encoded to multiple sub-carriers, while being sent simultaneously. This results in the optimal usage of bandwidth. The principles of OFDM modulation have been around since 1960s. However, recently, the attention toward OFDM has grown dramatically in the field of wireless and wired communication systems. A set of orthogonal sub-carriers together forms an OFDM symbol. To avoid ISI due to multi-path, successive OFDM symbols are separated by guard band. This makes the OFDM system resistant to multi-path effects. The main advantage of this transmission technique is their robustness to channel fading in wireless communication environment. This is reflected by the adoption of this technique in applications such as digital audio/video broadcast (DAB/DVB), wireless LAN (802.11a and HiperLAN2), broadband wireless (802.16) and xDSL. The main focus of this paper is to design IFFT and FFT blocks which are used in transmitter and receiver of the blocks diagram of OFDM system. The methodology used is the IFFT/FFT(DIT) with radix-2 butterfly algorithm. The design unit also consists of modulation and demodulation for mapping technique.