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| 1 | Recent advances and emerging trends of rare-earth-ion doped spectral conversion nanomaterials in perovskite solar cells显示文摘Organic-inorganic lead halide based perovskite solar cells(PSCs)have attracted unprecedented research interest over last decade.The high performance,combined with merits of low fabrication costs and ease of synthesis make PSCs promising alternate to state of the art silicon(Si)based solar cells.Howeve r,some inherent shortcomings of PSCs are hindering their market dominance over conventional photovoltaic technologies such as transmission loss of sub-bandgap photons,poor stability and hysteresis effects.Recently,use of rare earth(RE)ions doped nanomaterials in PSCs,has been identified as an effective means to address the aforementioned issues by expanding the range of absorption spectra minimizing the non-absorption loss of solar photons,enhancing light scattering and improving operational stability.This article reviews the recent progress in doping rare-earth(RE)ions in the building blocks of PSCs such as semiconductor electrodes and photoactive perovskite layers,and its use as a separate spectral conversion layer in PSCs.The effect of size,shape,constitution and concentration of RE-nanoparticles on the overall performance and device stability will be analyzed in detail.Moreover,we provide an outlook on the opportunities this newly developed field offers and the critical challenges faced in rationally and effectively using RE-ion-doped nanomaterials in PSCs for better operational stability and enhanced performance. | Syed Afaq Ali Shah Muhammad Hassan Sayyad Jinghua Sun Zhongyi Guo | 2022 | Journal of Rare Earths2022，40，11： | 4 |
| 2 | Transmit Power Optimization for Relay-Aided Multi-Carrier D2D Communication显示文摘In this paper,we consider the power optimization problem in Orthogonal Frequency Division Multiplexing(OFDM)-based relay-enhanced device-to-device(D2D) communication.In a single cell transmission scenario,dualhop communication is assumed in which each D2D user re-uses the spectrum of just one Cellular User(CU).In this work,we formulate a joint optimization scheme under a Decode-and-Forward(DF) relaying protocol to maximize the sum throughput of D2D and cellular networks via power allocation over different sub-carriers.The problem is thus transformed into a standard convex optimization,subject to individual power constraints at different transmitting nodes.We exploit the duality theory to decompose the problem into several sub-problems and use Karush–Kuhn–Tucker(KKT) conditions to solve each sub-problem.We provide simulation results to validate the performance of our proposed scheme. | Muhammad Waqas Guftaar Ahmad Sardar Sidhu Tayyaba Jabeen Muhammad Afaq Ahmad Muhammad Awais Javed | 2018 | Tsinghua Science and Technology2018，23，1： | 2 |
| 3 | An Intent-Driven Closed-Loop Platform for 5G Network Service Orchestration显示文摘The scope of the 5G network is not only limited to the enhancements in the form of the quality of service(QoS),but it also includes a wide range of services with various requirements.Besides this,many approaches and platforms are under the umbrella of 5G to achieve the goals of endto-end service provisioning.However,the management of multiple services over heterogeneous platforms is a complex task.Each platform and service have various requirements to be handled by domain experts.Still,if the next-generation network management is dependent on manual updates,it will become impossible to provide seamless service provisioning in runtime.Since the traffic for a particular type of service varies significantly over time,automatic provisioning of resources and orchestration in runtime need to be integrated.Besides,with the increase in the number of devices,amount,and variety of traffic,the management of resources with optimization becomes a challenging task.To this end,this manuscript provides a solution that automates the management and service provisioning through multiple platforms while assuring various aspects,including automation,resource management and service assurance.The solution consists of an intent-based system that automaticallymanages different orchestrators,and eliminates manual control by abstracting the complex configuration requirements into simple and generic contracts.The proposed systemconsiders handling the scalability of resources in runtime by usingMachine Learning(ML)to automate and optimize service resource utilization. | Talha Ahmed Khan Khizar Abbas Afaq Muhammad Wang-Cheol Song | 2022 | Computers, Materials & Continua2022，，3： | 1 |
| 4 | A Time Pattern-Based Intelligent Cache Optimization Policy on Korea Advanced Research Network显示文摘Data is growing quickly due to a significant increase in social media applications.Today,billions of people use an enormous amount of data to access the Internet.The backbone network experiences a substantial load as a result of an increase in users.Users in the same region or company frequently ask for similar material,especially on social media platforms.The subsequent request for the same content can be satisfied from the edge if stored in proximity to the user.Applications that require relatively low latency can use Content Delivery Network(CDN)technology to meet their requirements.An edge and the data center con-stitute the CDN architecture.To fulfill requests from the edge and minimize the impact on the network,the requested content can be buffered closer to the user device.Which content should be kept on the edge is the primary concern.The cache policy has been optimized using various conventional and unconventional methods,but they have yet to include the timestamp beside a video request.The 24-h content request pattern was obtained from publicly available datasets.The popularity of a video is influenced by the time of day,as shown by a time-based video profile.We present a cache optimization method based on a time-based pat-tern of requests.The problem is described as a cache hit ratio maximization pro-blem emphasizing a relevance score and machine learning model accuracy.A model predicts the video to be cached in the next time stamp,and the relevance score identifies the video to be removed from the cache.Afterwards,we gather the logs and generate the content requests using an extracted video request pattern.These logs are pre-processed to create a dataset divided into three-time slots per day.A Long short-term memory(LSTM)model is trained on this dataset to forecast the video at the next time interval.The proposed optimized caching policy is evaluated on our CDN architecture deployed on the Korean Advanced Research Network(KOREN)infrastructure.Our findings demonstrate how add-ing time-based request patterns impacts the system by increasing the cache hit rate.To show the effectiveness of the proposed model,we compare the results with state-of-the-art techniques. | Waleed Akbar Afaq Muhammad Wang-Cheol Song | 2023 | Intelligent Automation & Soft Computing2023，，6： | 0 |
| 5 | Mobility Management in Small Cell Cluster of Cellular Network显示文摘The installation of small cells in a 5G network extends the maximum coverage and provides high availability.However,this approach increases the handover overhead in the Core Network(CN)due to frequent handoffs.The variation of user density and movement inside a region of small cells also increases the handover overhead in CN.However,the present 5G system cannot reduce the handover overhead in CN under such circumstances because it relies on a traditionally rigid and complex hierarchical sequence for a handover procedure.Recently,Not Only Stack(NO Stack)architecture has been introduced for Radio Access Network(RAN)to reduce the signaling during handover.This paper proposes a system based on NO Stack architecture and solves the aforementioned problem by adding a dedicated local mobility controller to the edge cloud for each cluster.The dedicated cluster controller manages the user mobility locally inside a cluster and also maintains the forwarding data of a mobile user locally.To reduce the latency for X2-based handover requests,an edge cloud infrastructure has been also developed to provide high-computing for dedicated controllers at the edge of a cellular network.The proposed system is also compared with the traditional 3GPP architecture and other works in the context of overhead and delay caused by X2-based handover requests during user mobility.Simulated results show that the inclusion of a dedicated local controller for small clusters together with the implementation of NO Stack framework reduces the significant amount of overhead of X2-based handover requests at CN. | Adeel Rafiq Muhammad Afaq Khizar Abbas Wang-Cheol Song | 2021 | Computers, Materials & Continua2021，，10： | 0 |
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