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An effective method is proposed to estimate the desired-signal (S) subspace by the intersection between the signal-plus-interference (SI) subspace and a reference space covering the angular region where the desired signal is located. The estimated S subspace is robust to steering vector mismatch and overestimation of the SI subspace, capable of detecting the relative strength of the desired signal...
Spectrum sensing is an essential functionality of cognitive radio networks (CRN). Among existing spectrum sensing methods, cooperative spectrum sensing is the best one which can achieve superior sensing performance by introducing spatial diversity of sensing data sources. Such cooperation also introduces additional information exchanging which leads to extra power consumption and reporting delay....
The interharmonics monitoring system of power network was developed based on virtual instrument. The system consists of sensors, signal conditioning circuits, data acquisitions and computers. Within the system, the method of multiple signal classification(MUSIC) method was applied to virtual instrument by using the MATLAB script node in LabVIEW, the parameters of interharmonics are identified, some...
A novel approach for broadband beamforming in the presence of multi-path signals is proposed based on a frequency invariant transformation. In this approach, the received array signals are first processed by a frequency invariant beamforming network and then a traditional narrowband adaptive beamformer is applied to its output. It is shown that with the proposed structure, the cancellation of the...
Cognitive radios have the potential to greatly improve spectral efficiency in wireless networks. Cognitive radios are considered lower priority or secondary users of spectrum allocated to a primary user. Their fundamental requirement is to avoid interference to potential primary users in their vicinity. Spectrum sensing has been identified as a key enabling functionality to ensure that cognitive radios...
Cooperation can improve the performance of spectrum sensing. However, the sensing overhead is generally increasing with the number of cooperating users as more data needs to be reported to the fusion center. Most existing works assume a general time frame structure in which spectrum observing and sensing results reporting are conducted sequentially. We argue that this frame structure is inefficient,...
A novel adaptive beamforming method is proposed without the knowledge of the direction of arrival of the signal of interest. It is a combination of the traditional beamspace processing method and a recently proposed technique called ldquodomain weighted principal component analysis (DW-PCA)rdquo and can be applied to the case where the signal of interest is stronger than the interfering signals in...
A robust adaptive beamformer with new constraints on the array response is proposed to avoid signal cancellation in the environment where multi-path signals exist. The robustness is achieved by forcing the magnitude response of the desired signal and its multi-path signals exceeding unity in the presumed clusters while minimizing the output power. In this way, the desired signal is conbined with its...
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