共查询到19条相似文献,搜索用时 62 毫秒
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《中国计量学院学报》2015,(1):110-114
在多用户OFDMA资源分配中提出一种基于子载波权衡的资源分配算法.资源分配过程中,在对公平性最差的用户进行子载波分配时,进行子载波权衡.根据权衡后子载波信道增益的变化情况,进行子载波分配.通过子载波权衡,将待分配的子载波分配给权衡用户;同时对于公平性最差的用户,从已分配给权衡用户的子载波中获得一个权衡子载波;使得权衡后分配的子载波较权衡之前获得更高的信道增益.仿真结果表明,算法在保证用户公平性的同时,提升了系统的频谱利用率. 相似文献
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射频科技系统资源有限公司是一家拥有20余年包装与纸制品行业经验的香港公司。在大中华和亚太地区,该公司致力于成为一家创新性的RFID智能标签转换器与设备提供商。依靠旗下的专业研发团队及研发技术,射频科技系统资源有限公司可以提供可无缝应用于标签转换的革新性RFOD芯片解决方案。[编者按] 相似文献
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基于效用函数的IEEE 802.16 OFDMA系统资源分配算法 总被引:1,自引:0,他引:1
针对IEEE 802.16系统中复杂的服务质量(quality of service,Qos)机制,设计了一种统一的效用函数作为资源分配的目标函数以平衡资源分配中的效率和公平性,使资源分配问题转化为基于系统效用最大化的系统优化问题.考虑到对算法的实时性要求和适用于IEEE802.16正交频分复用多址(OFDMA)系统的要求,提出了一种基于效用函数的资源分配(URA)的算法.仿真结果表明,所提出的URA算法在性能上非常接近于最优算法,而计算复杂度却大幅度降低;同时,URA算法能够在频谱效率和公平性之间取得良好的折衷,以满足IEEE 802.16系统中各业务类型不同的QoS要求. 相似文献
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办公自动化系统(OA系统)目前已经成为各大企业内部信息通信一个基础性工具之一,同时也在逐渐成为企业间信息交流的重要手段。因为行业差异的存在,导致现在的大型企业的OA系统一般采用专门定购和定向开发的方式形成的。这样软件公测面相对较小,公测期也短,导致软件的功能和效率测试不全。 相似文献
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自动化存取系统控制优化研究综述 总被引:1,自引:0,他引:1
控制优化是提高自动化存取系统效率的有效途径。对比分析了自动化存取系统控制优化策略在生产和配送领域的应用特点,指出生产领域自动化存取系统控制优化主要关注货物出库的实时性,而配送领域则更关注货物出入库的总体平衡。调研了货位分配、停靠点策略、存取指令排序、订单批次化等主要控制优化问题的国内外研究成果,分析了自动化存取系统控制优化未来的研究方向。 相似文献
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《制冷与空调(北京)》2020,(11)
优化运行控制策略的研究可更好地发挥其"移峰填谷"优势,有利于降低冰蓄冷空调系统的运行费用。本文在简述冰蓄冷空调系统基本原理的基础上,对比分析了其常见运行策略,并从负荷预测和优化建模两个角度分析总结了国内外冰蓄冷空调系统优化运行控制的研究现状,最后对其未来发展方向提出建议。 相似文献
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针对正交频分多址接入(OFDMA)系统下行链路的混合业务调度问题,提出了一种基于队列等待时间的跨层调度算法.该算法联合利用了MAC层的队列等待时间与物理层的信道状态信息作为调度参数,通过队列等待时间反映用户的服务质量要求,并利用多用户分集增益提高系统性能;针对实时和非实时用户的不同服务质量要求,在队列等待时间的计算上采取了不同的策略;在子载波的分配过程中根据分配状态及时更新队列等待时间,使资源的利用更为有效.仿真结果表明,提出的算法可显著降低实时用户的平均时延和最大延时违反概率,同时保证了非实时用户的吞吐量需求,能够有效地支持下一代网络中混合业务的多种服务质量要求. 相似文献
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针对OFDMA系统多小区上行链路资源分配问题,提出了一种新的基于基站合作(BSC)和软频率复用(SFR)的资源分配方案。该方案通过相邻小区使用不同的子载波的软频率复用减少小区间干扰,利用基站合作对边缘用户的信号重构,使小区间干扰进一步消除,从而将多小区资源分配转化为单一小区资源分配。然后根据选择子载波避免冲突原则进行第一次子载波分配。最后根据速率要求,在不影响其他用户最低速率要求的前提下,对子载波进行二次分配。分析和仿真结果表明,该方案可以很好地解决小区边缘干扰严重的问题,降低用户的中断率,使多小区资源分配更加简单、公平、有效,尤其可保证边缘用户的服务质量,从而改善了系统的性能。 相似文献
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The flexibility of orthogonal frequency-division multiple access (OFDMA) technology necessitates a compromise between spectrum efficiency and quality of service (QoS) in IEEE 802.16 broadband wireless networks. This article proposes a complete solution with the nice feature of adaptive modulation and a coding scheme to provide both delay and loss rate guarantees for real-time services. The proposed method first determines the subframe boundary according to the current downlink and uplink backlogs. To comply with the IEEE 802.16 standard, the proposed method then groups contiguous subchannels and allocates them to proper connections based on the current loss rate and available modulation and coding schemes for each connection. By modeling the aggregated required subchannels as a Gaussian distribution, this study develops a simple admission control algorithm by checking if there are enough resources for a new connection. Simulation results show that the proposed solution can provide QoS guarantee with high spectrum efficiency. 相似文献
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The orthogonal frequency division multiplexing access (OFDM/OFDMA) based wireless transmission technology has been widely deployed in recent years. The frame check sequence (FCS) scheme is employed to enhance the reliability of OFDM/OFDMA systems. Since the padding overhead cannot be effectively avoided in OFDM/OFDMA when medium access control frames are encapsulated, we propose a novel cyclic redundancy check based error correction scheme by utilizing the padding space to carry extra segmented FCS information as much as possible; compared with the legacy FCS scheme, our approach greatly enhance the error detection and correction upon the first retransmission (second transmission). A significant performance improvement based on the simulation results is also demonstrated. 相似文献
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Jeroen de Mast Yohan van der Bijl 《Quality and Reliability Engineering International》2011,27(8):1095-1106
This paper aims to develop a unifying and quantitative conceptual framework for healthcare processes from the viewpoint of process improvement. The work adapts standard models from operation management to the specifics of healthcare processes. We propose concepts for organizational modeling of healthcare processes, breaking down work into micro processes, tasks, and resources. In addition, we propose an axiological model which breaks down general performance goals into process metrics. The connexion between both types of models is made explicit as a system of metrics for process flow and resource efficiency. The conceptual models offer exemplars for practical support in process improvement efforts, suggesting to project leaders how to make a diagrammatic representation of a process, which data to gather, and how to analyze and diagnose a process's flow and resource utilization. The proposed methodology links on to process improvement methodologies such as business process reengineering, six sigma, lean thinking, theory of constraints, and total quality management. In these approaches, opportunities for process improvement are identified from a diagnosis of the process under study. By providing conceptual models and practical templates for process diagnosis, the framework relates many disconnected strands of research and application in process improvement in healthcare to the unifying pursuit of process improvement. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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从设计和分析的本质出发,结合复杂系统的特点,通过分析传统设计优化流程在面对复杂系统时存在的困难和缺陷,指出多学科设计优化(multidisciplinary design optimization,MDO)方法是解决复杂系统设计优化问题的一种有效措施.在此基础上,介绍了多学科优化方法的基本思想,总结了子系统耦合方式及MDO在处理耦合时的基本方法,归纳了MDO的知识框架和主要研究内容.最后在现有研究成果的基础上,对MDO今后的研究提出了几点参考意见. 相似文献
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Bhatt M Siddhartha 《Sadhana》1984,7(3):237-258
Current focus on rural energy has resulted in the emergence of numerous strategies and a variety of technologies employing
different-conversion processes and sources. This paper suggests a methodology for finding out the overall first law system
efficiency for various routes of energy supply. The method is not an optimisation technique but gives clues regarding the
choice of energy sources for maximum overall efficiency of the system. Results indicate that a decentralised system with multi-energy
sources is the most efficient (efficiency 12%) for villages. 相似文献
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In this two part paper, we provide a survey of recent and emerging topics in wireless networking. We view the area of wireless
networking as dealing with problems of resource allocation so that the various connections that utilise the network achieve
their desired performance objectives. In the first part of the paper, we first survey the area by providing a taxonomy of
wireless networks as they have been deployed. Then, we provide a quick tutorial on the main issues in the wireless ‘physical’
layer, which is concerned with transporting bits over the radio frequency spectrum. Then, we proceed to discuss some resource
allocation formulations in CDMA(code division multiple access) cellular networks and OFDMA(orthogonal frequency division multiple
access) networks.
In the second part of the paper, we first analyse random access wireless networks and pay special attention to 802·11 (Wi-Fi)
networks.We then survey some topics in ad hoc multihop wireless networks, where we discuss arbitrary networks, as well as
some theory of dense random networks. Finally, we provide an overview of the technical issues in the emerging area of wireless
sensor networks. 相似文献