一种基于Android和JXTA协议模型的无线D2D通信技术

移动通信系统的快速发展使得频谱资源日益紧缺。D2D通信是一种在系统的控制下,允许终端之间通过复用小区资源直接进行通信的新型技术。它能减少小区网络的负载,还能支持新型的小范围点对点数据通信,是未来绿色通信发展的趋势。针对这一新型的通信技术,提出了基于Android OS平台,以JXTA协议为模型的无线D2D通信技术,使得移动终端之间能够进行通信与资源共享,并通过网络实验验证了其有效性。     

LTE系统中引入D2D技术后的干扰研究

D2D(终端到终端)是一种在LTE(长期演进)通信系统中通过重用小区内蜂窝用户的资源来实现终端到终端通信的新型技术。在LTE中引入D2D后,资源调度也随之发生变化,不仅体现在资源块的使用上,也体现在相应的功率控制机制上。D2D技术在提高系统容量的同时,也带来了新的干扰问题——普通蜂窝通信模式与D2D模式的相互干扰。通过协调好系统内蜂窝通信与D2D通信之间的干扰,可以提高系统的总体性能。     

混合D2D蜂窝网络中基于模拟退火算法的资源调度策略

D2D通信是未来5G网络中一种近距离直通通信方式,在通信过程中,信息直接由发送端传给接收用户,而不需要经过基站的转发.在传统蜂窝网络中引入D2D通信可以极大地提升系统的总吞吐量、增大频谱资源的利用率以及降低发射终端的功耗.主要介绍了一种适用于混合D2D蜂窝网络中的资源分配方法,通过拉格朗日乘子法结合模拟退火算法实现频谱资源的分配,提出一种同时考虑信道容量和能耗的基于模拟退火算法的资源调度策略.本算法在维也纳仿真平台上经仿真验证,相比于传统贪婪优化算法,可以明显增大系统总吞吐量和频谱资源利用率.另外,算法中采用了分布式资源调度方法,D2D用户根据算法步骤自行搜索适合的目标信道并计算其发射功率,可以有效减少基站的信令开销.     

提高蜂窝网络中数据分发效率的D2D协作转发算法

Device-to-Device(D2D)通信是一种移动终端在蜂窝通信系统的控制下使用授权频段进行点到点通信的新型技术。通过允许接收终端间的数据转发,D2D通信可以用来提高蜂窝网络中的数据分发效率。现有的终端间转发算法,没有充分考虑D2D链路的差异,很难实现频谱资源的高效利用。为此,该文提出了一种基于多跳中继的D2D协作转发算法,包括多播和单播两个模式。该算法根据D2D链路质量自适应地选择最优的中继、路由及传输跳数,能够充分利用D2D链路的多信道分集增益。仿真结果表明,该文所提出的算法能够显著地提高D2D转发的资源利用率,进而提升数据分发业务的吞吐量。     

D2D通信资源调度研究现状综述

终端直通技术(D2D)是一种终端在基站控制下直接进行通信而不需要基站转发的新型通信技术。D2D引入LTE-A蜂窝系统虽然可以带来吞吐量和频谱效率的提升,但是也会带来很大的干扰。综合近些年来的研究成果,合理的资源调度算法成为降低干扰,提升系统性能的关键。首先,描述了D2D通信技术引入LTE-A蜂窝网络后的系统干扰模型。然后,从模式选择、资源分配和功率控制三个方面综述了目前国内外文献关于资源调度算法的研究成果。     

异构蜂窝网络中基于Stackelberg博弈的能效优化算法

设备到设备(Device To Device,D2D)通信允许移动终端无需通过基站而进行直接通信。为提高蜂窝系统能效,引入D2D通信共享频谱资源形成异构蜂窝网络。本文将D2D通信的能效优化问题转化为博弈收益最大化问题,并提出了一种基于Stackelberg博弈的分布式功率控制算法。针对系统模型中存在的跨层干扰以及层内干扰,该算法建立了干扰价格系数与D2D对发送功率之间的函数关系,并求解出给定干扰价格系数下D2D对最佳发送功率的闭合表达式。仿真结果表明所提算法能够在最大化基站端蜂窝用户收益的基础上有效提高D2D对的总能效。      

基于安全中断概率的D2D安全接入策略

针对D2D蜂窝系统通信安全性受资源限制的问题,考虑到蜂窝链路和D2D链路的同频干扰能够为两者带来安全增益,基于此,提出一种基于安全中断概率的D2D用户接入策略。首先理论分析了蜂窝用户和D2D用户的安全中断概率,并给出了基于安全中断概率最小化的D2D用户功率优化算法。在上述分析的基础上,选择安全中断概率最小的D2D用户接入复用蜂窝用户的无线资源,同时提高D2D通信链路和蜂窝上行链路的安全性。最后,仿真结果证明了所提算法的有效性。     

在LTE-Advanced网络下的Device-to-Device通信

Device-to-Device（D2D）通信是一种在系统的控制下,允许终端之间通过复用小区资源直接进行通信的新型技术,它能够增加蜂窝通信系统频谱效率,降低终端发射功率,在一定程度上解决无线通信系统频谱资源匮乏的问题。与其他应用于非许可频段的同类技术相比,D2D具有干扰可控等优点。文章对D2D技术原理进行了介绍,阐述了它应用的必要性和应用场景、它对比同类技术的优点,以及在应用中的关键问题。     

D2D通信中干扰协调算法的研究

D2D(Device-to-Device,终端直通通信)技术是指用户可以直接进行通信而不用经过基站的一种终端直通通信技术,移动蜂窝使用终端直通通信技术能够增加蜂窝系统性能,然而却带来了较多的干扰以及加大了能量损耗.为了达到用户和基站间的相互干扰,增加频谱利用效率和能量利用效率,文章以D2D 用户和速率为优化目标提出了一种联合资源分配和功率控制的方法,用以达到高能效的终端直通通信.仿真结果表明:文章提出的联合信道分配和功率控制方案,能明显减少D2D用户与蜂窝系统受到的干扰,增加蜂窝频谱利用率以及D2D用户和速率.     

D2D通信中一种资源分配与功率控制结合的方案

以underlay方式工作的D2D(Device-to-Device)通信通过资源共享复用蜂窝网络中的资源,在提高系统资源利用率的同时,对已有蜂窝链路带来了同频干扰。为了减小因无线资源复用带来的干扰,提出了一种资源分配与功率控制相结合的方法。以最小化系统干扰为目的,通过在D2 D链路之间合理地分配资源,保证了蜂窝链路的通信质量;同时动态地调整D2 D链路的发射功率,在保证相应蜂窝链路干扰可控的情况下,合理提高了D2 D链路的通信质量。仿真结果表明,与现有方案相比,所提出的算法能够有效地提高D2 D通信与蜂窝用户共存场景下的系统性能。     

终端直通技术中通信系统模式的研究

随着移动通信的不断发展,5 GHz以下带宽分配已经十分拥挤,由于可用于移动通信的频谱资源有限,为满足无线通信发展的需要,可以用终端直通技术(D2D,Device-to-Device)来提高频谱利用率,并可以减少和基站通信的负担,这是新一代无线通信发展的趋势。但是在D2D通信系统中所选择的模式是十分关键的问题。这里给出了蜂窝模式和直通模式这2种通信模式,为了能更好地选择D2D的工作模式,通过仿真比较了这2种模式性能的优劣。     

D2D技术在LTE-A系统中的应用

Device-to-Device（D2D）是一种在LTE-A系统中通过重用小区内宏蜂窝用户的资源来实现端到端通信的新型技术。本文从实际应用的角度出发,首先对D2D技术的原理和应用进行了分析,然后讨论D2D技术应用于LTE-A系统中的优缺点,接着通过仿真验证了D2D技术在LTE-A系统中的优势。最后阐述了D2D技术在LTE-A系统中应用可研究的方向及技术展望。     

Electrical Interrogation of Thickness-Dependent Multiferroic Phase Transitions in the 2D Antiferromagnetic Semiconductor NiI2

2D magnetic materials hold promise for quantum and spintronic applications. 2D antiferromagnetic materials are of particular interest due to their relative insensitivity to external magnetic fields and higher switching speeds compared to 2D ferromagnets. However, their lack of macroscopic magnetization impedes detection and control of antiferromagnetic order, thus motivating magneto-electrical measurements for these purposes. Additionally, many 2D magnetic materials are ambient-reactive and electrically insulating or highly resistive below their magnetic ordering temperatures, which imposes severe constraints on electronic device fabrication and characterization. Herein, these issues are overcome via a fabrication protocol that achieves electrically conductive devices from the ambient-reactive 2D antiferromagnetic semiconductor NiI₂. The resulting gate-tunable transistors show band-like electronic transport below the antiferromagnetic and multiferroic transition temperatures of NiI₂, revealing a Hall mobility of 15 cm² V⁻¹ s⁻¹ at 1.7 K. These devices also allow direct electrical probing of the thickness-dependent multiferroic phase transition temperature of NiI₂ from 59 K (bulk) to 28 K (monolayer).     

D2D通信在5G中的应用研究

设备间直接通信(D2D)使得设备之间可以直接传输数据而无须基站转发,可有效降低网络负荷,降低传输时延,提高网络的频谱利用效率,扩大蜂窝网络的覆盖范围,提高系统吞吐量。5G不再只是从2G到3G再到4G的网络传输速率的提升,而是将"人与人"之间的通信扩展到"人—网—物"3个维度的万物互联,打造全移动和全连接的数字化社会。本文主要研究探讨D2D通信技术及其在5G中的应用。     

Atomically thin α-In2Se3: an emergent two-dimensional room temperature ferroelectric semiconductor

Room temperature ferroelectric thin films are the key element of high-density nonvolatile memories in modern electronics. However, with the further miniaturization of the electronic devices beyond the Moore’s law, conventional ferroelectrics suffer great challenge arising from the critical thickness effect, where the ferroelectricity is unstable if the film thickness is reduced to nanometer or single atomic layer limit. Two-dimensional(2D) materials, thanks to their stable layered structure, saturate interfacial chemistry, weak interlayer couplings, and the benefit of preparing stable ultra-thin film at 2D limit, are promising for exploring 2D ferroelectricity and related device applications. Therefore, it provides an effective approach to overcome the limitation in conventional ferroelectrics with the study of 2D ferroelectricity in van der Waals(vdW) materials. In this review article,we briefly introduce recent progresses on 2D ferroelectricity in layered vdW materials. We will highlight the study on atomically thin α-In2Se3, which is an emergent ferroelectric semiconductor with the coupled in-plane and out-of-plane ferroelectricity. Furthermore, two prototype ferroelectric devices based on ferroelectric α-In2Se3 will also be reviewed.     

基于OCDM的PON监控编码技术分析

鉴于OCDM的PON监控技术在多用户和实时监控方面的优越性,提出多种编码方案.主要介绍基于OCDM的PON监控技术的1D码、2D码、1D/2D混合码以及周期码的基本原理,并研究分析各种编码方案在监控性能上的优缺点.     

Functional 2D Phases in Mixed Dimensional Perovskite Photovoltaics

Organic-inorganic hybrid perovskite solar cells (PSCs) with unique properties exhibit their powerful competitiveness in the photovoltaic field over the past few years. However, the challenges of stability for perovskite devices limit the commercialization and further development. The 2D/3D hybrid structures combine the superior efficiency of bulk perovskites and the superior stability of layered perovskites and gradually get hotspots of the photovoltaic field. In addition, there remains a lack of comprehensive understanding and systematic summary of the function of 2D perovskite attributed to the complex nature of 2D/3D structures. Here, the latest progress of 2D/3D hybrid structures and focus on the functionality of 2D phases in mixed structures and the underlying mechanism from the perspective of their different distributions in the perovskite layer is summarized. Then, the insight and vital factors for overall improvements in the stability of 2D/3D structures are thoroughly discussed. Finally, it is expected that this review will contribute to the present challenges and future research prospects in the photovoltaic industry.     

Survey of software defined D2D and V2X communication

The related D2D (device-to-device) and V2X (vehicle-to-everything) are regarded as vital components of 5G communication system,which providing alternative network services and multiple application services for cellular network.In the meanwhile,SDN (software defined networking) can improve the compatibilities and flexibilities of D2D and V2X.SD-D2D (software defined D2D communication) and SD-V2X (software defined V2X communication) technologies were reviewed.Based on their similarities and respective characteristics,their state-of-arts and architectures were reviewed accordingly,and the key technologies such as D2D location/discovery management,D2D routing control,D2D flow table management,V2V path scheduling,and V2V path recovery were analyzed.Finally,it was pointed out that the SD-D2D architecture was approaching mature and the SD-V2X framework had been preliminarily determined,the existing problems of interference management,mobile management and routing management in D2D/V2X communication could be effectively solved.Furthermore,it was also pointed out that the disconnection between the existing SD-D2D/V2X studies and the actual application needed to be overcome.     

NKG2D配体在视网膜母细胞瘤RB细胞的表达及意义

目的：探讨视网膜母细胞瘤RB细胞株上NKG2D配体的表达情况及其对同种异体NK细胞杀伤活性的影响。方法：采用半定量RT-PCR法检测RB细胞及人红白血病细胞K562细胞上NKG2D配体MICA、MICB、ULBP1、ULBP2、ULBP3的mRNA表达情况。应用MTT法检测人NK细胞对肿瘤细胞的杀伤活性。结果：K562细胞表面表达MICA、MICB、ULBP1、ULBP2、ULBP3，RB细胞表面表达MICA、MICB、ULBP2、ULBP3不表达ULBP1。K562细胞表面NKG2D的配体mRNA表达强度明显强于RB细胞（P〈0．05）。当效靶比分别为5：1、10：1、20：1、40：1时NK细胞对K562、RB细胞的杀伤活性分别为28．32％±2．06％、9．11％±0．89％；45．62％±1．17％、22．87％±1．38％；60．79％±1．78％、32．69％±0．37％；73．83％±3．05％、50．29％±2．49％，在各效靶比时NK细胞对K562细胞的杀伤活性较RB细胞明显增强（P〈0．05）。结论：NKG2D配体影响NK细胞对靶细胞的杀伤活性，NKG2D配体表达水平可能决定着NK细胞抗肿瘤免疫应答的强弱，提高NKG2D配体的表达有可能提高NK细胞的抗肿瘤作用。     

Analysis of D2D‐pairing scheme based on Voronoi diagram in cellular networks

This paper presents a device‐to‐device (D2D)–pairing scheme based on Voronoi diagram, which establishes D2D links by the relation of transmission powers and link distances. Using the principle of stochastic geometry and channel inversion, the coverage probability is analyzed, we observe that the co‐channel interference caused by cellular networks is stable in theory, and the influence of link distance parameter is highlighted as well. According to the second‐order moment of link distance, the new metric space of D2D terminals set is constructed, in which Voronoi diagram is degenerated into Delaunay triangles set to represent the potential D2D links. In addition, on the basis of the mini‐max length criterion of Delaunay triangle, the D2D communication range–limiting algorithm is designed. Finally, the more intuitive results compared with conventional D2D communications are displayed by simulations. Owing to restraining the D2D communication range, lower co‐channel interference can be obtained. Specially, the D2D‐pairing scheme is approximate local optimal under the D2D communication range–limiting algorithm, and it can provide more fairness than greedy algorithm.