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We have examined the effect of gradual breaking of symmetry on a Fano resonant metamaterial, and have been able to understand the features using theoretical models and simulations. This study should provide a basis for choosing a specific structure for a given purpose. We have been able to obtain a continous range of Q of 7 to 13.
Several ultrawide band (UWB, 3.1–10.6 GHz) antennas are presented for either wireless communications or detection applications. An UWB antenna could be either a planer structure for portable devices or has a 3D configuration, which is suitable for an access point. Dielectric resonator is used to tremendously shrink an UWB antenna's size, which is important for a terminal device. Different DR loading...
Square‐planar bis(σ‐fluorophenylacetylide) platinum(II) complexes [Pt(Me3SiCCbpyCC‐SiMe3)(CCC6H4F)2] (CCC6H4F‐2 for 2, CCC6H4F‐3 for 3, and CCC6H4F‐4 for 4; Me3SiCCbpyCCSiMe3=5,5′‐bis(trimethylsilylethynyl)‐2,2′‐bipyridine) were prepared and were characterized by spectroscopic and luminescence studies, and X‐ray crystallography. The color and luminescence of crystalline complex 3 is specifically...
Opportunistic spectrum access is an important issue in cognitive radio systems. In this paper, we propose a distributed opportunistic spectrum access scheme based on sequential channel-sensing in decentralized CRN (cognitive radio network). Different from the traditional spectrum sensing scheme, the scheme proposed allows a secondary users to sense many channels one by one sequentially in a slot....
In the cognitive radio networks, the cognitive user must scan the multi-channel to acquire an idle channel before its cognitive transmission. If the sensing capability is limited, the user must sense the multi-channel one by one. So the sensing order is very crucial to the realization of maximum throughput. In this paper, we aim to find the optimal wideband sensing order in polynomial time which is...
The number of cooperative sensors to use is a compromise between sensing performance and resources usage efficiency. The definition of the optimal cooperative sensor set is given out firstly and then a greedy selection algorithm for the optimal cooperative sensor set is proposed which can use fewest cooperative sensors to maximize the resources usage efficiency, while still having enough for the sensing...
The number of sensors to use for cooperative sensing is a compromise between sensing performance and consumption of system resources. Firstly, the definition of optimal sensor set (OptSS) is given out. Then an optimal selecting method of OptSS is acquired. Lastly, a sub optimal adaptive selecting algorithm of OptSS based on greedy with a lower complexity is proposed, which not only obtains the near-optimal...
Although the method of cooperative spectrum sensing can greatly improve the sensing performance, the consumption of system resources will increase as the number of cooperative sensors increases, therefore, the number of cooperative sensors to use is a compromise between sensing performance and consumption of system resources. Firstly, based on the expression for the probability of detection, a sensor...
A cognitive scenario similar to BSS (basic service set) in CogMesh network is considered. Traditional MR (mesh router) is reconstructed into multi-transceiver structure, which called CMR (cognitive mesh router). CMR can allocate vacant spectrum bands for SMCs (secondary mesh client), which access the CMR with one hop. Besides, ESA algorithm is proposed according to the spectrum scenario based on the...
Wideband spectrum sensing is urgently in need for cognitive communication with wide spectrum range. When the cognitive user need to communication and when the exact primary user is found return, how to catch a new spectrum hole as fast and accurate as possible is becoming an intractable issue for the wideband cognitive user. In this paper, we propose a wideband sensing scheme for a cognitive user...
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