A spectrally Efficient Method for Reducing Intercarrier Interference in OFDM

Orthogonal Frequency Division Multiplexing (OFDM) is one of the principal techniques used for transmitting high rate data in wireless channels. However, there are several hurdles that need to be overcomed before OFDM finds widespread use in modern wireless communication systems. Conventional OFDM systems use a guard band known as cyclic prefix (CP) to avoid interference. For achieving this, the length of this CP should be at least equal to or longer than the maximum channel delay spread of the system. Even though this is simple solution for interference, it reduces the transmission efficiency of the system. Partial response coding (PRC) is found effective for combating intersymbol interference (ISI) in communication systems. In this paper, PRC is applied to OFDM systems for improving the system performance. Mathematical analysis of the intercarrier interference (ICI) in OFDM systems employing PRC is presented. It can be seen that ICI in partial response coded OFDM system is much less compared to the conventional OFDM system employing CP. Thus it can be inferred that the usage of PRC allows us to eliminate CP which in turn maximizes the spectral efficiency.