关键词: 认知无线电, 滤波器组多载波调制, 调制滤波器组, 原型滤波器, 插值的FIR滤波器

Abstract: As a new intelligent spectrum sharing technology, Cognitive Radio (CR) technology could effectively improve the spectrum utilization. It allows the cognitive user to use the idle spectrum of licensed user under the premise of free interference. Because of the high sidelobe attenuation, the traditional physical layer transmission technology in cognitive radio system, that is Orthogonal Frequency Division Multiplexing (OFDM) multi-carrier modulation technology, suffers from the the interference between the adjacent subbands and the interference among licensed users and cognitive users, an alternative multi-carrier modulation technology, filter bank based multi-carrer technology, was introduced in this paper to eliminate the interferences. An indirect design method for designing the prototype filter in filter bank was proposed while formulating the filter bank as an unconstrained linear optimization problem of prototype filter.Firstly,two low-order and linear lowpass filters were designed by using the Parks-McClellan algorithm, and then the prototype filter was optimally designed through the interpolation and cascade operation. Compared to the conventional direct method, the simulation results show that the modulated filter banks designed by the proposed method in this paper present better performance in the length of filter coefficients and the alias errors.

Key words: Cognitive Radio (CR), filter bank based multicarrier modulation, modulated filter bank, prototype filter, Interpolated FIR filter (IFIR)