http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Non-cooperative interference radio localization with binary proximity sensors
( Qihui Wu ),( Liang Yue ),( Long Wang ),( Guoru Ding ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.9
Interference can cause serious problems in our daily life. Traditional ways in localizing a target can`t work well when it comes to the source of interference for it may take an uncooperative or even resistant attitude towards localization. To tackle this issue, we take the BPSN (Binary Proximity Sensor Networks) and consider a passive way in this paper. No cooperation is needed and it is based on simple sensor node suitable for large-scale deployment. By dividing the sensing field into different patches, when enough patches are formed, good localization accuracy can be achieved with high resolution. Then we analyze the relationship between sensing radius and localization error, we find that in a finite region where edge effect can`t be ignored, the trend between sensing radius and localization error is not always consistent. Through theoretical analysis and simulation, we explore to determine the best sensing radius to achieve high localization accuracy.
Self-organized Spectrum Access in Small-cell Networks with Dynamic Loads
( Ducheng Wu ),( Qihui Wu ),( Yuhua Xu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.5
This paper investigates the problem of co-tier interference mitigation for dynamic small- cell networks, in which the load of each small-cell varies with the number of active associated small-cell users (SUs). Due to the fact that most small-cell base stations (SBSs) are deployed in an ad-hoc manner, the problem of reducing co-tier interference caused by dynamic loads in a distributed fashion is quite challenging. First, we propose a new distributed channel allocation method for small-cells with dynamic loads and define a dynamic interference graph. Based on this approach, we formulate the problem as a dynamic interference graph game and prove that the game is a potential game and has at least one pure strategy Nash equilibrium (NE) point. Moreover, we show that the best pure strategy NE point minimizes the expectation of the aggregate dynamic co-tier interference in the small-cell network. A distributed dynamic learning algorithm is then designed to achieve NE of the game, in which each SBS is unaware of the probability distributions of its own and other SBSs` dynamic loads. Simulation results show that the proposed approach can mitigate dynamic co-tier interference effectively and significantly outperform random channel selection.
Cathode interfacial layer-free all small-molecule solar cells with efficiency over 12%
Wu, Hao,Yue, Qihui,Zhou, Zichun,Chen, Shanshan,Zhang, Dongyang,Xu, Shengjie,Zhou, Huiqiong,Yang, Changduk,Fan, Haijun,Zhu, Xiaozhang The Royal Society of Chemistry 2019 Journal of materials chemistry. A, Materials for e Vol.7 No.26
<P>While nonfullerene small-molecule solar cells (NF-SMSCs) have relatively inferior performance compared with nonfullerene polymer solar cells, their performance is improving. In this work, a weak crystalline molecular donor BSFTR, was designed and synthesized to achieve efficient NF-SMSCs. By blending with a strong crystalline acceptor NBDTP-Fout, BSFTR achieves a well-intermixed blending morphology, which favors the formation of efficient charge percolation pathways with suppressed recombination. The BSFTR:NBDTP-Fout device obtains a power-conversion efficiency (PCE) of approximately 11.97% by achieving an efficient cathode interfacial layer (CIL)-free device that delivers an even higher PCE of 12.3%, which ranks among the top values for the reported NF-SMSCs. This work provides a simple solution for achieving high-performance NF-SMSCs by identifying the key factors for designing efficient, cost-saving, mass production-favorable CIL-free organic photovoltaic devices.</P>
Exploiting Multichannel Diversity in Spectrum Sharing Systems Using Optimal Stopping Rule
Yuhua Xu,Qihui Wu,Jinlong Wang,Alagan Anpalagan,Yitao Xu 한국전자통신연구원 2012 ETRI Journal Vol.34 No.2
This letter studies the problem of exploiting multichannel diversity in a spectrum sharing system, where the secondary user (SU) sequentially explores channel state information on the licensed channels with time consumption. To maximize the expected achievable throughput for the SU, we formulate this problem as an optimal stopping problem, whose objective is to choose the right channel to stop exploration based on the observed signal-to-noise ratio sequence. Moreover, we propose a myopic but optimal rule, called one-stage look-ahead rule, to solve the stopping problem.
Optimal Cooperation and Transmission in Cooperative Spectrum Sensing for Cognitive Radio
( Xian Zhang ),( Qihui Wu ),( Xiaoqiang Li ),( Zi Yun ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.2
In this paper, we study the problem of designing the power and number of cooperative node (CN) in the cooperation phase to maximize the average throughput for secondary user (SU), under the constraint of the total cooperation and transmission power. We first investigate the scheme of cooperative spectrum sensing without a separated control channel. Then, we prove that there indeed exist an optimal CN power when the number of CNs is fixed and an optimal CN number when CN power is fixed. The case without the constraints of the power and number of CN is also studied. Finally, numerical results demonstrate the characteristics and existences of optimal CN power and number. Meanwhile, Monte Carlo simulation results match to the theoretical results well.
Outage Analysis of CRNs with SC Diversity Over Nakagami-m Fading Environment
( Zongsheng Zhang ),( Qihui Wu ),( Xueqiang Zheng ),( Jinlong Wang ),( Lianbao Li ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.12
In this paper, we investigate the outage performance of a cognitive relay network. We consider mutual interference in an independent, non-identically distributed Nakagmai-m fading environment. We first derive the close-form outage probability expression, which provides an efficient means to evaluate the effects of several parameters. This allows us to study the impact of several parameters on the network`s performance. We then derive the asymptotic expression and reveal that the diversity order is strictly determined by the fading severity of the cognitive system. It is not affected by the primary network. Moreover, the primary network only affects the coding gain of the cognitive system. Finally, Monte Carlo simulations are provided, which corroborate the analytical results.
Optimal Adaptive Multiband Spectrum Sensing in Cognitive Radio Networks
( Long Yu ),( Qihui Wu ),( Jinlong Wang ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.3
In this paper, optimal sensing time allocation for adaptive multiband spectrum sensing-transmission procedure is investigated. The sensing procedure consists of an exploration phase and a detection phase. We first formulate an optimization problem to maximize the throughput by designing not only the overall sensing time, but also the sensing time for every stage in the exploration and detection phases, while keeping the miss detection probability for each channel under a pre-defined threshold. Then, we transform the initial non-convex optimization problem into a convex bilevel optimization problem to make it mathematically tractable. Simulation results show that the optimized sensing time setting in this paper can provide a significant performance gain over the previous studies.
( Changju Kan ),( Qihui Wu ),( Fei Song ),( Guoru Ding ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.4
Due to the low utilization and scarcity of frequency spectrum in current spectrum allocation methodology, cognitive radio networks (CRNs) have been proposed as a promising method to solve the problem, of which spectrum sensing is an important technology to utilize the precious spectrum resources. In order to protect the primary user from being interfered, most of the related works focus only on the restriction of the missed detection probability, which may causes over-protection of the primary user. Thus the interference probability is defined and the interference-aware sensing model is introduced in this paper. The interference-aware sensing model takes the spatial conditions into consideration, and can further improve the network performance with good spectrum reuse opportunity. Meanwhile, as so many fading factors affect the spectrum channel, errors are inevitably exist in the reporting channel in cooperative sensing, which is improper to be ignored. Motivated by the above, in this paper, we study the throughput tradeoff for interference-aware cognitive radio networks over imperfect reporting channel. For the cooperative spectrum sensing, the K-out-of-N fusion rule is used. By jointly optimizing the sensing time and the parameter K value, the maximum throughput can be achieved. Theoretical analysis is given to prove the feasibility of the optimization and computer simulations also shows that the maximum throughput can be achieved when the sensing time and the parameter of K value are both optimized.
A Novel Cooperative Spectrum Sensing Algorithm in Cognitive Radio Systems
Zheng, Xueqiang,Wang, Jinlong,Wu, Qihui,Shen, Liang The Korea Institute of Information and Commucation 2009 Journal of communications and networks Vol.11 No.2
In cognitive radio (CR) systems, cognitive users can use the frequency bands when the primary users are not present. Hence, reliable detection of available spectrum is foundation of cognitive radio technology. To ensure unimpaired operation of primary users, cooperative spectrum sensing is needed. To reduce the network overhead of cooperative spectrum sensing, a novel cooperative spectrum sensing algorithm based on credibility is proposed. In particular, the close-form expressions for probability of detection and false-alarm are derived for the novel algorithm, and expression for the average overhead used for cooperation is given. The thresholds design method for the algorithm is also discussed. The conclusion is proved by computer simulations.