Green energy powered cognitive radio (CR) network is capable of liberating the wireless access networks from spectral and energy constraints. The limitation of the spectrum is alleviated by exploiting cognitive networking in which wireless nodes sense and utilize the spare spectrum for data communications, while dependence on the traditional unsustainable energy is assuaged by adopting energy harvesting (EH) through which green energy can be harnessed to power wireless networks. Green energy powered CR increases the network availability and thus extends emerging network applications. Designing green CR networks is challenging. It requires not only the optimization of dynamic spectrum access but also the optimal utilization of green energy. This paper surveys the energy efficient cognitive radio techniques and the optimization of green energy powered wireless networks. Existing works on energy aware spectrum sensing, management, and sharing are investigated in detail. The state of the art of the energy efficient CR based wireless access network is discussed in various aspects such as relay and cooperative radio and small cells. Envisioning green energy as an important energy resource in the future, network performance highly depends on the dynamics of the available spectrum and green energy. As compared with the traditional energy source, the arrival rate of green energy, which highly depends on the environment of the energy harvesters, is rather random and intermittent. To optimize and adapt the usage of green energy according to the opportunistic spectrum availability, we discuss research challenges in designing cognitive radio networks which are powered by energy harvesters.
Index TermsCognitive radio (CR), spectrum efficiency, energy efficiency, energy harvesting.
In this paper, we present a new power allocation scheme for a decode-and-forward (DF) relayingenhanced cooperative wireless system. While both source and relay nodes may have limited traditional brown power supply or fixed green energy storage, the hybrid source node can also draw power from the surrounding radio frequency (RF) signals. In particular, we assume a deterministic RF energy harvesting (EH) model under which the signals transmitted by the relay serve as the renewable energy source for the source node. The amount of harvested energy is known for a given transmission power of the forwarding signal and channel condition between the source and relay nodes. To maximize the overall throughput while meeting the constraints imposed by the non-sustainable energy sources and the renewable energy source, an optimization problem is formulated and solved. Based on different harvesting efficiency and channel condition, closed form solutions are derived to obtain the optimal source and relay power allocation jointly. It is shown that instead of demanding high on-grid power supply or high green energy availability, the system can achieve compatible or higher throughput by utilizing the harvested energy.
Despite improvements in asthma control and ICS and PFM compliance compared with past literature, the current level of asthma control countrywide continues to fall short of the goals set in the GINA.
Primary ciliary dyskinesia (PCD) is clinically characterized by neonatal respiratory distress, chronic sinusitis, bronchiectasis and infertility, and situs inversus in 50% of the patients. PCD is a result of mutations in genes encoding proteins involved in ciliary function, and is primarily inherited in an autosomal recessive fashion. Diagnosis of PCD is often a challenging task due to its high clinical and genetic heterogeneities. In the present study, we attempted to use whole-exome sequencing (WES) combined with runs of homozygosity (ROH) approaches to identify the genetic defects in four Chinese consanguineous families with clinical PCD. We successfully identified three recently acknowledged PCD genes: DYX1C1, CCNO and ARMC4, and one well-characterized PCD gene, DNAI1. Our study provides compelling evidence that WES in combination with ROH analysis is an efficient diagnostic tool for identifying genetic causes of PCD in consanguineous families. Furthermore, our work expands the genetic mutation spectrum in PCD, and provides the additional tools to better serve the counseling of the families with PCD.
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