Time-Delay Estimation in Dispersed Spectrum Cognitive Radio Systems
Time-Delay Estimation in Dispersed Spectrum Cognitive Radio Systems
复制标题
色散频谱认知无线电系统中的时延估计
DOI：
10.1155/2010/675959
复制
发表时间：
2009
影响因子：
1.9
通讯作者：
H. Poor
中科院分区：
文献类型：
--
作者：
Fatih Kocak;H. Çelebi;S. Gezici;Khalid A. Qaraqe;Huseyin Arslan;H. Poor
研究了认知无线电系统中的时延估计问题，以利于频谱资源的机会性利用。一个两步的方法，提出了获得准确的时间延迟估计的信号，同时占用多个分散的频带，具有显着较低的计算复杂度比最佳的最大似然（ML）估计。在所提出的方法的第一步中，ML估计器用于信号的每个频带，以估计占用该频带的信号的未知参数。然后，在第二步骤中，以各种方式组合来自第一步骤的估计，以便获得最终的时间延迟估计。在第二步骤中使用的合并技术被称为最优合并、信噪比（SNR）合并、选择合并和相等合并。结果表明，在高信噪比下，最优合并技术的性能非常接近Cramer-Rao下界。这些合并技术提供了各种机制的分集合并的时间延迟估计和扩展的概念，在通信系统中的分集的时间延迟估计问题在认知无线电系统。仿真结果评估所提出的估计器的性能，并验证了理论分析。
Time-delay estimation is studied for cognitive radio systems, which facilitate opportunistic use of spectral resources. A two-step approach is proposed to obtain accurate time-delay estimates of signals that occupy multiple dispersed bands simultaneously, with significantly lower computational complexity than the optimal maximum likelihood (ML) estimator. In the first step of the proposed approach, an ML estimator is used for each band of the signal in order to estimate the unknown parameters of the signal occupying that band. Then, in the second step, the estimates from the first step are combined in various ways in order to obtain the final time-delay estimate. The combining techniques that are used in the second step are called optimal combining, signal-to-noise ratio (SNR) combining, selection combining, and equal combining. It is shown that the performance of the optimal combining technique gets very close to the Cramer-Rao lower bound at high SNRs. These combining techniques provide various mechanisms for diversity combining for time-delay estimation and extend the concept of diversity in communications systems to the time-delay estimation problem in cognitive radio systems. Simulation results are presented to evaluate the performance of the proposed estimators and to verify the theoretical analysis.