FBMC系统中的SR-NYQ原型滤波器设计  

Design of SR-NYQ prototype filter in an FBMC system

作　　者：闻建刚 华惊宇 徐志江[1] 李枫 陈浩[1] Jiangang WEN;Jingyu HUA;Zhijiang XU;Feng LI(College of Information Engineering, Zhejiang University of Technology, Hangzhou 310023, China;School of Information and Electronic Engineering, Zhejiang Gongshang University, Hangzhou 310018, China)

机构地区：[1]浙江工业大学信息工程学院,杭州310023 [2]浙江工商大学信电学院,杭州310018

出　　处：《中国科学：信息科学》2019年第7期886-899,共14页Scientia Sinica(Informationis)

基　　金：国家自然科学基金(批准号:61471322)资助项目

摘　　要：FBMC (filter bank multicarrier)作为新一代移动通信中的候选方案,相对于OFDM (orthog onal frequency division multiplexing)具有旁瓣衰减大、无需严格正交同步等多个方面的优势,在实现子载成形的原型滤波器上起到了重要作用.目前,常用FBMC原型滤波器包括PHYDYAS滤波器和IOTA滤波器,但在两者的相应设计中,可控参数较少而灵活性欠佳.因此,本文提出了一种约束优化方法来直接设计FBMC滤波器.在该方法中,将滤波器的阻带误差能量作为优化目标,目的在于减小FBMC波形的旁瓣泄漏.同时,通过近似方法在频域对NYQ (Nyquist)条件进行约束,实现对符号间干扰的控制.该NYQ约束包含线性矩阵不等式和针对截止频点的线性不等式,避免了原始约束中由卷积计算引起的非凸问题.通过半定规划算法可对约束优化问题进行求解,所得线性相位FIR (finite impulse response)滤波器能够在适当放宽NYQ条件的同时有效改善阻带衰减特性,从而提升FBMC波形的频率选择特性.误码率仿真结果表明优化所得滤波器相对于PHYDYAS滤波器和IOTA滤波器具有一定优势.此外,在本文设计方法下,可采用长度更短的滤波器,其BER(bit error rate)与采用PHYDYAS滤波器时的BER结果近似可比,而其乘法复杂度比PHYDYAS滤波器低.As a candidate for next generation mobile communication, filter bank multicarrier (FBMC) has several advantages over orthogonal frequency division multiplexing (OFDM), such as larger side-lobe attenuation and no requirements of strict orthogonality and synchronization, in which the prototype filter for subcarrier shaping plays an important role. Currently, the commonly used proto type filters include the PHYDYAS filter and the IOTA filter, but in the corresponding design of both, there are few controllable parameters and the filters' flexibility is insufficient. Therefore, a constrained optimization met hod to directly design the FBMC filter is proposed herein. In this method, the error energy in the stopband is considered the optimization target, which is aimed at reducing the side-lobe leakage of the FBMC waveform. Furthermore, the constraints on the Nyquist (NYQ) condition are implemented in the frequency domain via approximation, through which the control of inter-symbol interference can be achieved. These NYQ constraints contain linear matrix inequalities and a linear inequality for the cut-off frequency point, which circumvent the nonconvex problem caused by the convolution calculation in original constraints. After solving the constrained optimization via semi-definite programming, the designed FIR filter with linear phase can effectively improve stopband attenuation characteristics when the NYQ condition is suitably relaxed, thus improving the frequency selectivity of the FBMC waveform. The bit error rate (BER) simulations indicate that the optimized filters have a certain superiority over the PHYDYAS and IOTA filters. In addition, using the proposed method, the designed filter with shorter length can also result in a BER comparable to that of the PHYDYAS filter, with a multiplication complexity is lower than that of the PHYDYAS filter.

关 键 词：滤波器组多载波 原型滤波器 Nyquist条件 阻带能量 误码率 

分 类 号：TN713[电子电信—电路与系统]