Effect of Guard Time on BER Performance of OFDM based WiMAX (IEEE 802.16d) System

The demand of mobile Internet and wireless multimedia applications are growing faster than ever. To satisfy the user requirements and to overcome the limitations of existing wireless technologies, have led the researchers to come up with more advanced and efficient technology. Orthogonal Frequency Division Multiplexing (OFDM) based WiMAX (Worldwide Interoperability for Microwave Access ) is the outcome in this direction which promises to solve the last mile access technology to provide high speed internet access in the residential as well as small and medium sized enterprise sectors. In this paper we have analyzed Bit Error Rate (BER) performance of the WiMAX Physical layer baseband conforming to the parameters established by IEEE 802.16 standards under different Guard time intervals between OFDM symbols. The performance was also extended for different digital modulation schemes. From the analysis it was observed that all the digital modulation schemes with cyclic prefix or guard time of 1/32 provides resistant to inters symbol interference (ISI) thereby improving BER performance with limited SNR.