Interference-driven designs of nonlinear-phase FIR filter with application in FBMC system

In the forthcoming 5G systems, new technologies, such as amorphous networks and non-orthogonal filter bank multi-carriers (FBMC), provide an effective way to accommodate high-rate transmissions. Meanwhile, the prototype filter affects the adjacent channel interference, and therefore is important for FBMC systems. Besides, once the amorphous network is taken into account, the requirement for interference control must be much stricter. Accordingly, this paper focuses on the design of prototype filter with better ability of interference controlling, where we exploit the nonlinear phase FIR filter (NLPFF) instead of traditional linear phase FIR filter (LPFF) to achieve more optimization spaces under a small sacrifice of linear phase. In our designs, both the amplitude and phase responses are handled independently to approach the stop-band performance enhancements, in while the nearly perfect reconstruction (NPR) conditions are relaxed by pre-specified thresholds. Computer simulations confirm the effectiveness of the NLPFF designs, and demonstrate the advantages of the proposed NLPFF in FBMC applications.