Compromise between spectral efficiency and interference cancellation in OFDM system

OFDM (Orthogonal Frequency Division Multiplexing) has attracted significant attention, and become very promising technique to ensure high data rate wireless communication systems, thanks to its resistance to the frequency selectivity of the channel. However, this technique has major drawbacks such as the Adjacent Channel Interference (ACI), due to the out of band radiation, which can be generated because of the limited-time of each sub-carrier signal for each symbol. Others multipath problems faced by the OFDM are the inter symbol Interference (ISI) and Inter channel interference (ICI) due to the spectral overlap of channels. To overcome these problems a guard interval and a guard band should be inserted cyclically to extend the OFDM symbol. Even so, this insertion can lead to a reduction of the spectral efficiency by the redundancy in the guard interval and with the virtual carrier that does not convey any information. To compensate for this loss, minimizing the guard interval and guard band while maintaining orthogonality and eliminating interferences is studied. In this paper, the insertion of the GB and GI and its effect on the BER and the OOB radiation are shown with simulations to find a compromise between this insertion and the spectral efficiency and BER performance.