Reduction of Fading and Noise Factor Using OFDM and CDMA in Digital Communication

Orthogonal Frequency Division Multiplexing (OFDM) is a type of modulation technique that has become one of the most popular modulation schemes for wireless communications. It is used in many applications such as Digital Video Broadcasting (DVB-T/DVB-H), WiMAX, and LTE. OFDM reduces the amount of fading and noise in the channel, which allows for the transmission of larger data amounts with fewer errors. OFDM performs multiplexing of the data across many subcarriers resulting in more robust transmission when used in a multipath fading channel. OFDM is immune to the inter-symbol interference caused by multipath fading, since the subcarriers have orthogonality. OFDM divides the data stream into several parallel sub-streams and modulates them onto many carriers. This reduces multipath fading and facilitates the use of equalization and channel estimation techniques to further improve performance. Results from tests show that OFDM can reduce fading and noise factors significantly when compared to conventional modulation techniques.