Reduction of Out of Band Radiation Using Carrier-by-Carrier Partial Response Signaling in OFDM
Orthogonal Frequency Division Multiplexing (OFDM) is a mature and one of the most popular Multi-Carrier Modulation (MCM) techniques. Also, it is the main candidate for physical layer of Cognitive Radio (CR) networks. CR is a new method to satisfy ubiquitous demand for wireless services while there is no enough unlicensed spectrum. However, the most important shortcoming of OFDM-based CR systems is the high level of Out Of Band (OOB) components that originate from simple Fast Fourier Transform (FFT)-based implementation. In this paper, the authors propose a novel method to reduce side-lobes of OFDM spectrum. In this method proper carrier-by-carrier partial response signaling is used on the modulated symbols across the time.