A low complexity OFDM system with minimum intersymbol interference

Different guard interval techniques for the Orthogonal Frequency Division Multiplexing (OFDM) transmission are suggested to reduce the interference between successive symbols (i.e. Inter-Symbol Interference, ISI) and interference between different carriers within the same symbol (i.e. Inter-Carrier Interference, ICI). In this paper, the impact of replacing the Cyclic Prefix (CP) by zeros insertion (ZI) before the Inverse Fast Fourier Transform (IFFT) process on OFDM is studied. Associated with each OFDM symbol, the zeros will be added in the transmitter before the IFFT process. For symmetry of the OFDM symbol, the zeros will be inserted with the same length among the OFDM frames. The ZI acts as a buffer region where delayed information from the previous symbols can get stored. The receiver has to exclude samples from the ZI which got corrupted by the previous symbol when choosing the samples for an OFDM symbol. The motivation of using the ZI instead of the cyclic prefix is the reduction in the transmission rate and the high performance in reducing of the channel distortion. The performance comparison among the proposed ZI technique, the CP, Zero Padding (ZP), and Known Symbol Padding (KSP) is introduced in this paper. The results show that the KSP has a slightly worse performance; however, the proposed ZI approach provides better performance than the other techniques and achieves 20% reduction in the data redundancy relative to the redundancy in the CP-OFDM system.