检索结果-南通市图书馆

Waiting time in block fading MIMO systems with dynamic-depth interleaving

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(information {2.) 2010年第8期53卷 1622-1627页

作者： GUO HaiYou 1,2., HU HongLin 1,2.& ZHANG Yan 3 1 Key Laboratory of wireless Sensor Network & communication, {2., chinese academy of sciences, shanghai 2.0050, china 2.shanghai research Center for wireless communications, shanghai 2.0335, china 3 Simula research Laboratory, Lysaka 132., Norway 1. Key Laboratory of wireless Sensor Network & communication Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China2. Shanghai Research Center for Wireless Communications Shanghai 200335 China3. Simula Research Laboratory Lysaka 1325 Norway

Interleaving is an efficient measure to resolve the bursty errors in a block fading multiple-inputs multiple-outputs (MIMO) system. For the metrics of network layer, interleaving exerts two conflicting effects on the ultimate delay performance. Specifically, interleaving can advantageously reduce data transmit time. On the other hand, it comes at a cost, entailing an undesired delay penalty resulting from interleaving depth. Here, we exploit a unified model to accommodate these two conflicting effects, and derive the average waiting time in block fading MIMO systems with dynamic-depth interleaving. Such a unified model is developed with a combined method of both information theory and queueing theory. Therefore, the model is capable of characterizing the randomness of data arrival process, hence the nature of dynamic-depth interleaving. The methodology and the results are applicable to designing, evaluating, and tuning the practical interleaving systems.

关键词： dynamic-depth interleaving multiple-inputs multiple-outputs (MIMO) queueing analysis waiting time

research progress in terahertz quantum cascade lasers

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(information {2.) 2012年第1期55卷 16-26页

作者： CAO JunCheng Key Laboratory of Terahertz Solid-State technology,shanghai institute of microsystem and information technology,{2.,shanghai 2.0050,china 1. Key Laboratory of Terahertz Solid-State technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

The terahertz(THz)quantum cascade laser(QCL)is a coherent THz source based on intersubband transitions of unipolar *** semiconductor lasers,THz QCLs are solid-state,electrically pumped,tunable,and can be easily *** paper reviews the state of the art for the design,operation temperature,and output power of THz *** applications in THz communication and imaging are also discussed.

关键词： terahertz quantum cascade laser communication imaging

Channel characterization at 12. GHz for future indoor communication systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Physics B 2013年第5期22卷 650-656页

作者：陈镇曹俊诚 Key Laboratory of Terahertz Solid-State technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences

We present a simulation on the spatial and temporal characteristics of the indoor propagation channel at 12. GHz. The simulation, applied to a dynamic scenario with randomly placed objects and moving people in a room, is based on a three-dimensional ray-tracing method. Propagation and reflection mechanisms of electromagnetic waves are discussed in the channel model. The received power in a 0.95-m-height plane is obtained. Comparison between walls and ceiling covered with dielectric mirrors and those with three common wall and ceiling materials are presented. The result shows that the holistic received power level with dielectric mirrors is about 10 dB higher than with other materials.

关键词： sub-terahertz communication channel models ray tracing electromagnetic propagation

A survey of next generation mobile communications researchin {2.

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2011年第5期56卷 2875-2888页

作者： TIAN JinFeng 1,2., ZHENG XiaoYing 2.3 , HU HongLin 1,2.YOU XiaoHu 1,3 1 shanghai research Center for {2. communications (WiCO), shanghai 2.0335, china 2.shanghai institute of microsystem and information technology (SIMIT), chinese academy of sciences (CAS), shanghai 2.0050, china 3 National Mobile communications research Laboratory, Southeast University (SEU), Nanjing 2.0096, china shanghai research Center for {2. communications (WiCO) shanghai institute of microsystem and information technology (SIMIT) Chinese Academy of Sciences (CAS) National Mobile communications research Laboratory Southeast University (SEU)

With the rapid development of wireless communication networks, the fourth generation (4G) has emerged to move beyond the limitations of the third generation (3G), with increased bandwidth, enhanced quality of services, and reduced costs of resources. In this paper, we discuss the key technologies of 4G and focus on surveying the ongoing {2. in 4G communications in china. The 4G technologies under investigation include multicarrier transmission, multiple antenna techniques, carrier aggregation, relays, cognitive radio, distributed antenna systems, network convergence, and network self-optimization. These technologies are the building blocks of 4G and contribute largely to the requirements of International Mobile Telecommunications Advanced (IMT-Advanced). For each technology, its benefits, {2. topics, and some existing approaches are examined. Finally, we briefly discuss the challenges and future {2. issues in 4G systems.

关键词：下一代移动通信中国无线通信网络分布式天线系统 4G系统多载波传输国际移动通信认知无线电

同方期刊数据库

Performance analysis of LDPC codes on OOK terahertz wireless channels

在线全文

学校读者我要写书评

暂无评论

chinese Physics B 2016年第2期25卷 553-557页

作者：刘纯王长曹俊诚 Key Laboratory of Terahertz Solid-State technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Science

Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz（THz） wireless communications. An error control coding scheme based on low density parity check（LDPC） codes with soft decision decoding algorithm is proposed to improve the bit-error-rate（BER） performance of an on-off keying（OOK） modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications.

关键词： terahertz wireless channels low density parity check codes atmospheric turbulence gamma-gamma models

Power-efficient topologies for wireless sensor networks with fixed communication range

在线全文

学校读者我要写书评

暂无评论

Journal of shanghai University(English Edition) 2010年第1期14卷 39-44页

作者：金彦亮缪慧俊王晖葛泉熊勇 Key Laboratory of Special Fiber Optics and Optical Access Networks Shanghai University CNRS-IBISC research Laboratory University of Evry Val d'Essonne Key Laboratory of wireless Sensor Network and communication Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences

The expectations for sensor networks are growing. The performance of wireless sensor networks （WSNs） is greatly influenced by their network topology. In this paper, we consider four patterned topologies that best support connectivity among these deployed sensor nodes in two-tiered WSNs. The theoretical and simulation results show that the triangle-based topology has smaller cell number, shorter maximum hop length, less total energy consumption, and better performance than other topologies. The analysis carried out in this paper could provide the guidelines for network deployment and protocol design in the future applications.

关键词： wireless sensor network (WSN) network topology coverage connectivity

一种基于块结构广义多载波的无干扰重叠传输机制

在线全文

学校读者我要写书评

暂无评论

上海交通大学学报 2009年第7期43卷 1113-1116页

作者：贠超李明齐易辉跃刘广宇杨曾卜智勇中国科学院上海微系统与信息技术研究所上海200050 上海无线通信研究中心上海200050

提出了一种能够有效提高快结构广义多载波(BW-GMC)系统效率的传输机制.利用BW-GMC系统中原型滤波器的对称性,在发射端构造包含原信号和叠加信号的重叠传输信号,在接收端提出了相应检测方案,以实现原信号和叠加信号的无干扰分离.理论分... 详细信息

提出了一种能够有效提高快结构广义多载波(BW-GMC)系统效率的传输机制.利用BW-GMC系统中原型滤波器的对称性,在发射端构造包含原信号和叠加信号的重叠传输信号,在接收端提出了相应检测方案,以实现原信号和叠加信号的无干扰分离.理论分析结果表明,与传统系统相比,采用无干扰重叠传输机制的BW-GMC系统能有效提高传输效率,并且传输效率增益取决于信噪比以及BW-GMC中的逆滤波器组变换符号个数.仿真结果进一步验证了该传输机制的无干扰特性.

关键词：块结构广义多载波重叠传输滤波器组

Optimal power allocation for cognitive relay networks: amplify-and-forward versus selection relay

在线全文

学校读者我要写书评

暂无评论

Science china(information {2.) 2011年第4期54卷 861-872页

作者： YUE WenJing 1,2.ZHENG BaoYu 1,2.MENG QingMin 1,YUE WenJie 3 & CUI JingWu 1 1 institute of Signal Processing and Transmission,Nanjing University of Posts and Telecommunications,Nanjing 2.0003,{2. 2.Department of Electronic Engineering,shanghai Jiaotong University,shanghai 2.02.0,{2. 3 Shanxi institute of Educational Science,Taiyuan 030009,{2. 1. institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China2. Department of Electronic Engineering Shanghai Jiaotong University Shanghai 200240 China3. Shanxi Institute of Educational Science Taiyuan 030009 China

We consider a cognitive relay network which is defined by a source,a destination,and cognitive relay nodes and primary user *** this network,a source is assisted by cognitive relay nodes which allow coexisting with primary user nodes by imposing severe constraints on the transmission power so that they operate below the noise floor of primary user *** this paper,we mainly study the power allocation strategies of this system to minimize the outage probability subject to total and individual power constraints for cognitive relay nodes and subject to interference constraints for primary user nodes.A relay transmission scheme,namely amplify-and-forward (AF),is *** first present an optimal power allocation (OPA) scheme to minimize the system outage probability,based on instantaneous channel state information among the source,destination and relay nodes and mean channel gains between primary user nodes and cognitive ***,we propose a selection AF scheme (S-AF) where the single best relay is chosen to assist in the transmission and study power allocation strategy for S-AF to minimize outage *** analytical power allocation strategies have been validated through numerical *** results indicate that the AF with OPA and S-AF with OPA have significantly better outage behavior and average throughput than AF and S-AF schemes *** also find that S-AF with OPA achieves a higher throughput,and hence lower outage probability than AF with OPA.

关键词： cognitive radio (CR) relay networks power allocation outage probability

Robust cooperative spectrum sensing schemes for fading channels in cognitive radio networks

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(information {2.) 2011年第2期54卷 348-359页

作者： YUE WenJing1,2. ZHENG BaoYu1,2. MENG QingMin1, CUI JingWu1 & XIE PeiZhong1 1institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 2.0003, {2. 2.epartment of Electronic Engineering, shanghai Jiaotong University, shanghai 2.02.0, {2. 1. institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China2. Department of Electronic Engineering Shanghai Jiaotong University Shanghai 200240 China

In cognitive radio systems, cooperative spectrum sensing can detect the presence of the primary user accurately. In practice, however, since the sensing observations are forwarded to a data collector through fading channels, the sensing performance is severely degraded. To deal with this problem, in this paper, we first propose a secondary user selection based cooperative spectrum sensing method to improve sensing performance by decreasing the reporting errors introduced by the fading channels. More specifically, only the secondary users with better signal-to-noise ratio (SNR) for reporting channels are allowed to send their local binary decisions (0 or 1) to the data collector while the others will send nothing. Additionally, we further propose a diversity based cooperative spectrum sensing method which applies existing space-time coding. By exploiting space diversity in CR network, the reporting errors introduced by the fading channel can be decreased and then the sensing performance is improved significantly. For either proposed cooperative spectrum sensing method, the sensing performance is derived and the analytical performance results are given. Our analysis and numerical results verify that proposed methods outperform the conventional cooperative spectrum sensing with OR-rule by taking into account the error effect on the reporting channels.

关键词： cognitive radio (CR) spectrum sensing energy detection diversity technique space-time coding