Reconfigurable wireless platforms for spectrally agile coexistence

In this paper, we present a novel and practical filtering approach for mitigating the effects of out-of-band (OOB) emissions produced by spectrally agile waveforms based on orthogonal frequency division multiplexing (OFDM)-type modulation schemes. As opposed to OOB filtering approaches presented in the open literature, which are based on filters employing a finite impulse response (FIR), the approach proposed in this paper employs infinite impulse response (IIR) filters to mitigate OOB emissions while avoiding the issues associated with FIR filters. In order to realize the proposed approach in a programmable wireless system, such as those based on field programmable gate array (FPGA) technology, fixed-point realizations of a family of IIR filters were implemented such that the appropriate filter can be used in real time given a specific transmission scenario and spectral characteristics. Results show that the bit error rate performance of the proposed approach is significantly better than the performance offered by other techniques.