全文获取类型
收费全文 | 343篇 |
免费 | 36篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 8篇 |
综合类 | 33篇 |
机械仪表 | 3篇 |
矿业工程 | 1篇 |
武器工业 | 1篇 |
无线电 | 267篇 |
一般工业技术 | 9篇 |
自动化技术 | 70篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 34篇 |
2013年 | 26篇 |
2012年 | 36篇 |
2011年 | 41篇 |
2010年 | 43篇 |
2009年 | 40篇 |
2008年 | 35篇 |
2007年 | 36篇 |
2006年 | 17篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 1篇 |
排序方式: 共有392条查询结果,搜索用时 15 毫秒
11.
12.
Distributed uplink scheduling in OFDMA systems is considered. In the proposed model, mobile terminals have the responsibility of making their own transmission decisions. The proposed scheme is based on two dimensional reservation in time and frequency. Terminals use channel state information in order to favor transmissions over certain subchannels, and transmission is done in a probabilistic manner. The proposed approach provides more autonomy to mobile devices in making transmission decisions. Furthermore, it allows avoiding collisions during transmission since it leads to collision detection during the resource reservation phase. The proposed approach is compared to other random access methods and shown to be superior in terms of increasing sum-rate, reducing the number of users in outage, and reducing the collision probability in the reservation phase. 相似文献
13.
针对目前OFDMA系统上行信道信息的反馈量大和公平性欠佳的问题,提出了减少上行反馈的资源
分配算法,该算法在高信噪比下,小区中心的用户不需要反馈CQI,而在低信噪比的小区边缘,当用户量小
时,采用1B反馈,当用户量大时,采用基于门限的Best-M反馈方案.同时,根据Best-M反馈方案,提出了对
第1个用户优先选择方案.本文算法在保证资源分配必要的反馈信息的前提下,对复杂度和性能之间进了折
中,同时满足了用户之间资源分配的公平性 相似文献
14.
Yuan-Cheng LaiAuthor Vitae Yen-Hung ChenAuthor Vitae 《Computer Standards & Interfaces》2012,34(1):68-79
Many burst construction algorithms have been proposed for Orthogonal Frequency Division Multiple Access (OFDMA). However, none meets the burst structure characteristics required by the IEEE 802.16 standard. In this study, two heuristic algorithms, Best Corner Oriented (BCO) and Best Subchannel Oriented (BSO), are proposed to provide high throughput for uplink burst construction in IEEE 802.16 networks. The BCO maintains all available slots as a continuous area and attempts to construct each burst from one of the two ending slots of this area. The BSO, however, constructs each burst in its best quality subchannels to adopt a better modulation coding scheme (MCS). The simulation results under a heavy load indicate that BSO and BCO achieve 2 and 1.5 times, respectively, the throughput achieved by Raster, the conventional algorithm. However, the superior performance of BSO is achieved at the expense of increased time complexity. 相似文献
15.
SC—FDMA技术作为3GPPLTE上行链路多址技术,它联合了单载波调制技术、正交频率复用和频域均衡技术(FDE),是一种新的多址技术。文中概述了SC—FDMA技术,分析了子载波分配对系统的影响以及与OFDMA、DS—CDMA技术间的联系。 相似文献
16.
17.
In this contribution, we present a survey on the radio resource allocation techniques in orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA) systems. This problem goes back to 1960s and that is related to properly and efficiently allocate the radio resources, namely subcarriers and power. We start by overviewing the main open issues in OFDM. Then, we describe the problem formulation in OFDMA, and we review the existing solutions to allocate the radio resources. The goal is to discuss the fundamental concepts and relevant features of different radio resource management criteria, including water-filling, max–min fairness, proportional fairness, cross-layer optimization, utility maximization, and game theory, also including a toy example with two terminals to compare the performance of the different schemes. We conclude the survey with a review of the state-of-the-art in resource allocation for next-generation wireless networks, including multicellular systems, cognitive radio, and relay-assisted communications, and we summarize advantages and common problems of the existing solutions available in the literature. The distinguishing feature of this contribution is a tutorial-style introduction to the fundamental problems in this area of research, intended for beginners on this topic. 相似文献
18.
针对OFDMA中继网络的两跳特性,提出一种基于两跳匹配的中继网络联合资源分配算法。首先根据中继网络的两跳性建立两跳速率匹配模型,然后利用对偶分解理论将中继网络资源分配的主问题分解为:中继选择、子载波分配和功率分配三个主要的子问题并进行联合优化,同时基于中继网络两跳性在子载波分配的过程中考虑两跳子载波配对,以逼近系统最优解。最后为了保证算法的公平性,考虑子载波分配因子约束以优化子载波分配。仿真结果表明:所提算法将中继选择、两跳子载波配对与功率分配联合优化以进一步提升系统吞吐量,同时引入子载波分配因子约束,保证了算法的公平性。 相似文献
19.
20.
大规模MIMO OFDMA下行系统能效资源分配算法 总被引:4,自引:0,他引:4
针对大规模多输入多输出(MIMO)正交频分多址(OFDMA)下行移动通信系统,提出了一种基于能效最优的资源分配算法。所提算法在采用迫零(ZF)预编码的情况下,以最大化系统能效的下界为准则,同时考虑每个用户的最低速率要求,通过调整带宽分配、功率分配和基站天线数分配来优化能效函数。首先根据优化条件提出了一种迭代算法确定每个用户的带宽分配,然后利用分数规划的性质并采用凸优化方法,通过联合调整基站端的发射天线数和用户的发射功率来优化能效函数。仿真结果表明,所提算法在较少迭代次数的同时能够取得较好的系统能效性能和吞吐量性能。 相似文献