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Active point modification for sidelobe suppression with PAPR constraint in OFDM systems 总被引:1,自引:0,他引:1
In this paper, we propose an active point modification (APM) scheme to suppress the sidelobe of orthogonal frequency division multiplexing (OFDM) signals, and the key idea of APM is slightly enlarging the amplitudes of constellation points on some sub-carriers while keeping unchanged the minimum distance between constellation points. Moreover, the peak-to-average power ratio of the OFDM signal is considered. We formulate the sidelobe suppression problem by APM as a quadratically constrained quadratic programming problem, which could be solved by numerical tools. Simulation results show that APM could provide well sidelobe suppression performance while the peak-to-average power ratio could be efficiently controlled at a desired level. 相似文献
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A kind of novel binary phase code named sidelobe suppression code is proposed in this paper. It is defined to be the code whose corresponding optimal sidelobe suppression filter outputs the minimum sidelobes. It is shown that there do exist sidelobe suppression codes better than the conventional optimal codes-Barker codes. For example, the sidelobe suppression code 相似文献
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WangFeixue OuGang ZhuangZhaowen 《电子科学学刊(英文版)》2004,21(1):33-36
A kind of novel binary phase code named sidelobe suppression code is proposed in this paper.It is defined to be the code whose corresponding optimal sidelobe suppression filter outputs the minimum sidelobes.It is shown that there do exist sidelobe suppression codes better than the conventional optimal codes-Barker codes.For example,the sidelobe suppression code of length 11 with filter of length 39 has better sidelobe level up to 17dB than that of Barker code with the same code length and filter length. 相似文献
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In this letter, a method for sidelobe suppression in OFDM systems is proposed and investigated. The proposed method is based on the multiplication of the used subcarriers with subcarrier weights. The subcarrier weights are determined in such a way that the sidelobes of the transmission signal are minimized according to an optimization algorithm which allows several optimization constraints. As a result, sidelobe suppression by subcarrier weighting reduces OFDM sidelobes by more than 10 dB in the average without requiring the transmission of any side information. 相似文献
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由于合成孔径雷达(SAR)特殊的成像机制,导致了SAR图像上出现了旁瓣效应(SVA)。针对舰船目标检测过程中,旁瓣效应改变了强反射目标的形状导致的定位困难与定位错误问题,该文提出了一种基于空间变迹滤波与有序统计恒虚警率(OS-CFAR)的舰船检测算法。该算法将空间变迹滤波算法运用到复图像数据中,针对目标检测要求的实时性问题进行算法改进,通过全局CFAR只对潜在目标点进行旁瓣抑制而忽略对舰船检测无意义的大量背景点,在抑制旁瓣的同时减少了算法运算量。然后采用非线性的OS-CAFR算法对旁瓣抑制后的图像进行目标检测,并且采用形态学膨胀运算,弥补SVA算法可能造成的像素点幅值错误降低的问题。最后利用高分三号(GF-3)的实测数据进行验证,通过对比有无使用该文算法的结果的图像对比度与检查目标个数,体现了算法的有效性。 相似文献
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针对MIMO探地雷达中随机步进频信号的距离旁瓣较高的问题,提出了一种基于快速二阶锥优化问题的旁瓣抑制方法。该方法首先通过建立随机步进频信号模型对回波信号进行预处理,然后基于回波信号的旁瓣特点将旁瓣抑制问题转化为以信号的峰值旁瓣构建目标函数,以主峰损失、峰值旁瓣和积分旁瓣联合约束的二阶锥优化问题,最后使用内点法求解二阶锥规划问题,以此得到最优的旁瓣滤波器系数。仿真和实测数据处理结果表明,设计的失配滤波器能够在较低主峰损耗的情况下,有效降低峰值旁瓣电平和积分旁瓣电平,提高信号的主旁瓣比。该方法为MIMO探地雷达中的距离旁瓣问题提供了有效解决思路,有望在工程应用中提高探地雷达的性能。 相似文献
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针对传统的宽带MVDR自适应波束形成中,抑制干扰的同时会抬高旁瓣电平,且过多的线性约束会导致波束输出的SINR性能下降的问题,提出了一种基于SRV约束和稀疏约束的低旁瓣、高增益宽带自适应波束形成方法.该方法在窄带MVDR自适应波束形成基础上,通过增加波束图稀疏约束来降低波束的旁瓣电平,同时利用空间响应偏差(SRV)约束将窄带算法推广到宽带MVDR 自适应波束形成中,极大地降低了算法的复杂度,改善了波束输出的SINR 性能.与传统方法相比,该方法在降低宽带波束的旁瓣电平的同时,还具有良好的干扰抑制效果.数值仿真实验验证了该方法的有效性. 相似文献
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Zhiqiang Wang Daiming Qu Tao Jiang Mahmoud Daneshmand 《Mobile Networks and Applications》2011,16(5):544-552
Recently, increasing attention is paid to improving the spectrum utilization in cognitive OFDM systems. To enable coexistence
between secondary users and primary users, a scheme, called as extended active interference cancellation (EAIC), was proposed
for the effective sidelobe suppression of OFDM signals. However, with the EAIC method, the cancellation signals cause self-interferences
to OFDM data subcarriers, which seriously degrades the symbol-error-rate performance, especially, when a high order modulation
is used. In this paper, we analyze the self-interferences and formulate the minimization of both the total sidelobe power
and the self-interferences as a optimization problem, which could be solved by least square method with acceptable complexity
for OFDM communication systems nowadays. Simulation results show that the proposed EAIC-IC scheme provides a good sidelobe
suppression performance of about 38.0 dB with signal-to-noise ratio loss less than 0.10 dB at symbol-error-rate of 10 − 3 when 64 QAM modulation is employed. Moreover, the proposed EAIC-IC scheme can provide an arbitrary tradeoff between the sidelobe
suppression and the symbol-error-rate performance via adjusting the constraint parameter. 相似文献
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线性调频信号主瓣不展宽旁瓣抑制方法 总被引:1,自引:0,他引:1
以汉明窗为代表的加权方法在抑制线性调频信号的匹配滤波输出峰值旁瓣的同时展宽主瓣,致使距离分辨力下降。为兼顾旁瓣抑制和高距离分辨力的需求,该文提出一种新的主瓣不展宽旁瓣抑制方法。该方法首先将匹配滤波和加权处理的输出幅度进行归一化处理,然后逐点进行比较,再取各点对应的最小值作为最终的输出数据。该方法兼取了匹配滤波和加权处理的优点,其-3 dB主瓣展宽系数与匹配滤波相比仅为1,而旁瓣抑制性能和对应的加权处理相当。仿真结果和湖上试验验证了该方法的有效性。 相似文献
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相控阵天线由于馈电误差的影响,旁瓣电平恶化,抗干扰能力降低。由于馈电误差随机分布,提出了采用数字统计特征分析旁瓣电平恶化情况的方法。论述了均值旁瓣电平和峰值旁瓣电平的基本原理。通过理论分析和数值模拟,计算了峰值旁瓣电平的概率密度分布,并给出了抑制旁瓣电平恶化的一些措施。 相似文献
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OFDM系统中存在较大的峰均比(Peak-to-Average Power Ratio,PAPR),特别在多径信道中接收的信号严重失真,星座图恶化,严重影响了系统传输性能。针对该问题,对多径信道下OFDM系统PAPR抑制进行研究,采用频域均衡技术,提出了一种多径信道下基于压缩扩张的OFDM系统PAPR抑制算法。仿真结果表明,所提算法在抑制PAPR的同时能消除多径效应影响,避免信号失真和星座图恶化。对比传统算法,所提算法星座图EVM最大降低0.19,抑制PAPR能力提升1 dB。 相似文献
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In order to obtain better target identification performance, an efficient waveform design method with high range resolution and low sidelobe level for orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) radar is proposed in this paper. First, the wideband CP-based OFDM signal is transmitted on each antenna to guarantee large bandwidth and high range resolution. Next, a complex orthogonal design (COD) is utilized to achieve code domain orthogonality among antennas, so that the spatial diversity can be obtained in MIMO radar, and only the range sidelobe on the first antenna needs suppressing. Furthermore, sidelobe suppression is expressed as an optimization problem. The integrated sidelobe level (ISL) is adopted to construct the objective function, which is solved using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. The numerical results demonstrate the superiority in performance (high resolution, strict orthogonality, and low sidelobe level) of the proposed method compared to existing algorithms. 相似文献
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结合几何成形与概率成形的思想,提出了一种适用于比特交织编码调制系统的星座成形映射方法。该方法基于实用信号星座,通过不使用部分能量较大的信号点并利用多对一的映射关系,使发送信号逼近最佳输入概率分布。利用解调器和译码器之间的迭代译码,该方法可方便地获得成形增益。基于容量和外信息转移图分析,给出了信号星座和信号到符号映射的优化方法。理论分析和仿真结果表明,在高斯白噪声信道和独立Rayleigh衰落信道下,该映射方法利用大信号星座在采用迭代译码的比特交织编码调制系统中均能取得优于传统Gray映射的误码性能,且随着调制阶数的增大可进一步提高成形增益。 相似文献
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针对水声换能器的指向性旁瓣级问题,该文提出了一种低旁瓣非均匀圆形活塞平面水声换能器。该换能器在均匀圆形活塞换能器的基础上,采取去双环分布方法去除均匀圆形活塞换能器部分压电相体积,改变换能器结构,实现了抑制旁瓣的效果。以均匀连续平面活塞阵为基础,该文推导了去双环圆形平面活塞阵指向性函数,并采用Matlab对该指向性函数求解,分析两个环的位置和宽度随换能器指向性最大旁瓣级的变化规律,根据优化结果确定了换能器的最优尺寸。通过有限元仿真分析表明,该去双环圆形活塞换能器指向性最大旁瓣级为-25.3 dB,与均匀圆形活塞换能器相比,最大旁瓣级降低了8.3 dB,实现了旁瓣抑制,有效降低了最大旁瓣级。 相似文献