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    • 23. 发明授权
    • Method and appratus for spectrum sensing for OFDM systems employing pilot tones
    • 用于采用导频音调的OFDM系统的频谱感测的方法和应用
    • US08867634B2
    • 2014-10-21
    • US13138585
    • 2010-03-12
    • Hou-Shin ChenWen Gao
    • Hou-Shin ChenWen Gao
    • H04K1/10H04L27/00H04L5/00
    • H04L27/0006H04L5/0007
    • Methods and apparatuses for OFDM spectrum sensing are provided. The proposed spectrum sensing algorithms are based on Time-Domain Symbol Cross-Correlation (TDSC-MRC and TDSC-NP methods) and can be applied to all existing wireless OFDM systems. The statistical behaviors of the TDSC-based spectrum sensors are explicitly analyzed. In addition, the spectrum sensing method employing the Cyclic Prefix of the OFDM modulated signals (CP method) is described for comparison purposes. The DVB-T Standard is adopted as an application example to illustrate the proposed spectrum sensing algorithms. Simulation results show that the TDSC-MRC method outperforms the CP method for all values of CP ratio considered. The TDSC methods have the advantage that the detection performances are the same for different CP ratios, while the detection performance of the CP method degrades dramatically when the CP ratio becomes small.
    • 提供了OFDM频谱感测的方法和装置。 所提出的频谱感知算法基于时域符号交叉相关(TDSC-MRC和TDSC-NP方法),并且可以应用于所有现有的无线OFDM系统。 明确分析了基于TDSC的频谱传感器的统计特性。 另外,为了进行比较,描述了使用OFDM调制信号的循环前缀的频谱感测方法(CP方法)。 采用DVB-T标准作为应用示例来说明所提出的频谱感知算法。 模拟结果表明,考虑到所有CP比值,TDSC-MRC方法优于CP方法。 TDSC方法的优点在于,对于不同的CP比,检测性能相同,而当CP比变小时,CP方法的检测性能显着降低。
    • 26. 发明申请
    • AUTOCORRELATION-BASED SPECTRUM SENSING FOR FM SIGNALS
    • 基于自适应的FM信号的频谱感测
    • US20120238227A1
    • 2012-09-20
    • US13514584
    • 2009-12-21
    • Wen GaoHou-Shin Chen
    • Wen GaoHou-Shin Chen
    • H04B1/04
    • H04W16/10H04L27/10
    • A method and system for detection of available a white space channel in an area of licensed transmitters includes a detector which utilizes the autocorrelation analysis of a channel in an frequency modulated (FM) band. Calculation of the autocorrelation excludes an initial set of correlation delay values such that large values of autocorrelation are removed. The remaining autocorrelation based on higher correlation delay values exposes the sinusoidal nature of an FM transmitter operating in the selected channel. White space becomes available to a user if no transmitter is detected using the autocorrelation detection method.
    • 用于在许可发射机的区域中检测可用的空白信道的方法和系统包括利用频率调制(FM)频带中的信道的自相关分析的检测器。 自相关的计算排除了初始的相关延迟值集合,从而消除了大的自相关值。 基于较高相关延迟值的剩余自相关显示在所选频道中操作的FM发射机的正弦特性。 如果没有使用自相关检测方法检测到发射机,则空白可用于用户。
    • 28. 发明申请
    • TIME -FREQUENCY SYNCHRONIZATION AND FRAME NUMBER DETECTION FOR DMB-T SYSTEMS
    • DMB-T系统的时频同步和帧数检测
    • US20110002418A1
    • 2011-01-06
    • US12733571
    • 2008-07-23
    • Hou-Shin ChenWen Gao
    • Hou-Shin ChenWen Gao
    • H04L7/00H04L27/06
    • H04L7/08H04L7/041H04L7/043H04L27/2602H04L27/2656H04L27/2675
    • A DMB-T receiver supports a single carrier (SC) form of modulation and a multi-carrier form of modulation such as orthogonal frequency division multiplexing (OFDM). Upon receiving a broadcast signal, the DMB-T receiver downconverts the received broadcast signal to a received base-band signal and determines a frame number for each frame by correlating groups of the received symbols in adjacent signal frames. In particular, the receiver determines a maximum right-shift correlation value and a maximum left-shift correlation value. If the magnitude of the maximum right-shift correlation value is greater than, or equal to, the magnitude of the maximum left-shift correlation value, then the maximum right shift correlation value is used to retrieve a frame number from a look-up table. Otherwise, the negative value of the maximum left-shift correlation value is used to retrieve a frame number from the look-up table.
    • DMB-T接收机支持单载波(SC)形式的调制和诸如正交频分复用(OFDM)的多载波调制形式。 在接收到广播信号时,DMB-T接收机将所接收的广播信号下变频为接收到的基带信号,并通过相邻信号帧中接收的符号组相关来确定每帧的帧号。 特别地,接收机确定最大右移相关值和最大左移相关值。 如果最大右移相关值的大小大于或等于最大左移相关值的幅度,则最大右移相关值用于从查找表中检索帧号 。 否则,最大左移相关值的负值用于从查找表中检索帧号。