基于旁瓣抑制的新型多载波传输技术研究

发布时间：2018-04-05 11:50

本文选题：多载波　切入点：正交频分复用　出处：《电子科技大学》2017年博士论文

【摘要】：以正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)为代表的多载波系统具有抗窄带干扰、抗频率选择性衰落和频谱效率高的优点,是无线通信物理层的重要传输技术。然而,OFDM传输波形在非正交频点存在较高的旁瓣,旁瓣叠加会导致严重的频谱泄露,从而对相邻频段造成干扰,影响了系统的频谱利用率。因而,如何高效地抑制多载波旁瓣,降低频谱泄露,从而提升频谱利用率,是未来移动通信物理层亟待解决的问题。针对上述问题,本文研究了基于旁瓣抑制的新型多载波传输技术,分别对子载波块和单个子载波进行了高效的旁瓣抑制,提出了一系列降低频谱泄露的信号处理方法,力求在误码率性能、频谱泄露、计算复杂度等因素之间取得较好的平衡。本文的研究内容如下:第一,研究了基于子载波块的旁瓣抑制技术。本文提出了一种时域构造的N连续OFDM(Time-Domain N-continuous OFDM,TD-NC-OFDM)方法:首先,探索了时域基向量的设计准则,设计了基于基集合的旁瓣抑制信号和收发信机结构;其次,探讨了时域平滑性和频域旁瓣的关系,给出了时域N连续OFDM信号的频谱表达式;最后,通过理论分析,推导出了新系统中信干噪比的闭合表达式。为了改善时域N连续OFDM的误码率,简化信号检测的复杂度,本文进一步提出了一种低干扰的时域N连续OFDM算法:该算法根据旁瓣抑制信号的时域分布特征,优化了旁瓣抑制信号的时域波形,降低了旁瓣抑制信号引入的干扰,从而显著提升了系统的传输性能。第二,研究了基于单个子载波的旁瓣抑制技术。本文针对低旁瓣的广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统,通过引入离散Gabor变换(Discrete Gabor Transform,DGT)的数学构造,提出了一种高效的频域DGT信号检测算法,并理论推导了信号干扰、信道特性和GFDM滤波器的制约关系。此外,为了进一步降低GFDM的实现复杂度,本文基于合成窗和解析窗的频域局部特性,提出了一种简化的频域DGT检测算法,通过理论分析,证明了简化算法具有最优解析窗,能够在无线衰落信道下获得较好的误码率性能。第三,研究了基于子载波块和单个子载波的联合旁瓣抑制技术。基于N连续OFDM和GFDM技术,本文提出了一种时域N连续GFDM(Time-Domain N-continuous GFDM,TD-NC-GFDM)方法:首先,研究了适合GFDM波形的基集合和旁瓣抑制信号结构;其次,分析了时域N连续GFDM信号的低干扰特性;最后,提出了迭代的干扰消除算法。最后,研究了频域旁瓣和时域峰均比的联合抑制技术。本文将N连续OFDM与串行峰值抵消相结合,提出了一种高效的联合抑制方法,并通过凸集映射的理论,分析了频域旁瓣抑制处理和时域峰均比抑制处理在时频域特性的制约关系;本文还提出了相应的接收端信号恢复算法,以改善系统的误码率性能。
[Abstract]:The multicarrier system, represented by orthogonal Frequency Division Multiplexing OFDM (OFDM), has the advantages of anti-narrowband interference, anti-frequency selective fading and high spectral efficiency. It is an important transmission technology in the physical layer of wireless communication.However, OFDM transmission waveforms have high sidelobe at non-orthogonal frequency points, the superposition of sidelobe will lead to serious spectrum leakage, which will interfere with adjacent frequency bands and affect the spectrum efficiency of the system.Therefore, how to efficiently suppress multi-carrier sidelobe, reduce spectrum leakage and improve spectrum efficiency is an urgent problem to be solved in the physical layer of mobile communication in the future.In order to solve the above problems, a new multi-carrier transmission technology based on sidelobe suppression is studied in this paper. The efficient sidelobe suppression for sub-carrier block and single sub-carrier is carried out, and a series of signal processing methods to reduce spectrum leakage are proposed.We strive to achieve a good balance between error rate performance, spectrum leakage, computational complexity and other factors.The main contents of this paper are as follows: first, the sidelobe suppression technique based on subcarrier block is studied.In this paper, a time-domain constructed N-continuous OFDM(Time-Domain N-continuous OFDM TD-NC-OFDM method is proposed. Firstly, the design criteria of the time-domain basis vector are explored, and the sidelobe suppression signal and transceiver structure based on the basis set are designed.The relationship between time domain smoothness and frequency domain sidelobe is discussed, and the spectrum expression of time domain N continuous OFDM signal is given. Finally, through theoretical analysis, the closed expression of CITIC signal-to-noise ratio is derived.In order to improve the bit error rate of N-continuous OFDM in time domain and simplify the complexity of signal detection, a low-interference N-continuous OFDM algorithm in time domain is proposed in this paper. The algorithm is based on the time-domain distribution characteristics of sidelobe suppression signal.The time domain waveform of sidelobe suppression signal is optimized, and the interference induced by sidelobe suppression signal is reduced, thus improving the transmission performance of the system.Secondly, the sidelobe suppression technique based on single subcarrier is studied.In this paper, for generalized Frequency Division multiplexing (GFDM) system with low sidelobe, an efficient frequency domain DGT signal detection algorithm is proposed by introducing discrete Gabor transform (discrete Gabor transform), and signal interference is derived theoretically.The relationship between channel characteristics and GFDM filters.In addition, in order to further reduce the complexity of GFDM implementation, this paper proposes a simplified frequency-domain DGT detection algorithm based on the local characteristics of synthetic and analytic windows in frequency domain. Through theoretical analysis, it is proved that the simplified algorithm has an optimal analytic window.It can obtain better bit error rate performance in wireless fading channel.Thirdly, the joint sidelobe suppression technique based on subcarrier block and single subcarrier is studied.Based on N continuous OFDM and GFDM techniques, a time domain N continuous GFDM(Time-Domain N-continuous GFDM TD-NC-GFDM method is proposed. Firstly, the base set and sidelobe suppression signal structure suitable for GFDM waveforms are studied; secondly, the low interference characteristics of time domain N continuous GFDM signals are analyzed.Finally, an iterative interference cancellation algorithm is proposed.Finally, the joint suppression technique of side lobe and time domain peak-to-average ratio (PAPR) in frequency domain is studied.In this paper, an efficient joint suppression method is proposed by combining N continuous OFDM with serial peak cancellation. By using the theory of convex set mapping, the constraints of frequency domain sidelobe suppression and time domain peak-to-average ratio suppression are analyzed.In order to improve the bit error rate (BER) performance of the system, a corresponding signal recovery algorithm is proposed in this paper.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN929.53

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