Time and Frequency Domain NBI Mitigation in OFDM Based Overlay Systems

Kurzfassung

In order to enhance spectral efficiency the coexistence of a licensed system and an additional overlay system based on orthogonal frequency-division multiplexing (OFDM) in the same frequency band is proposed. In an overlay scenario the overlay system is exposed to severe interference originating from licensed systems that degrades its performance significantly. In this paper, two different approaches to mitigate narrow-band interference (NBI) are presented. By windowing the received OFDM signal in time domain the influence of the interference signal is reduced. Interference mitigation in frequency domain aims at compensating the leakage effect, i.e. the spreading of the NBI signal over the complete overlay system bandwidth. When both methods are applied jointly NBI can be reduced such that it causes only a small loss in bit-error-rate performance.