Sidelobe Suppression using AIC technique in OFDM-based Cognitive Radios

Abstract

Orthogonal frequency division multiplexing (OFDM) is an efficient and effective trans-mission technique for
Cognitive radio (CR) systems but it suffers from out-of-band (OOB) radiations due to high spectral sidelobes. This is one
of the major drawback of OFDM scheme especially in cognitive radios where it is important to prevent secondary user’s
interference into the primary licensed user’s (LUs) frequency band. In this paper, we investigate the already existing
technique called Active Interference Cancellation (AIC]) to overcome the sidelobe problem in OFDM on different
parameters. In this technique, a few tones at both edges of the spectrum hole and in the PU band are used to cancel the
interference to LUs. Two special tones are called Active interference edge tones. The motto of all this is to cancel
interference in that band. Unlike other methods, this technique does not affect receiver and need small alterations in the
receiver and also there is no need of side information to be sent to the receiver