A sub-wavelength polarization insensitive X-band absorber based on interleaved concept

In this paper, a miniaturized absorber realized on interleaved structure across X-band is reported. The presented absorber has been designed based on the concept of complementary interleaved Brigid’s cross. Results show that the structure rejects 9.88 GHz with absorption rate of almost 99%. Moreover, the absorber is polarization independent, as it maintains stability against TE- and TM-polarizations. The results from waveguide simulator and space wave measurements provide an efficient absorber at sub-wavelength spacing.     

A new C-RAN architecture based on RF signal soft-switching

Coordinated multi-point (CoMP) is known to be one of the key technologies for long-term evolution (LTE)-advanced systems. CoMP technology can improve system capacity and the quality of wireless communication services for users in LTE networks. However, in practice, the actual performance of CoMP technology is limited by the switching capacity of the backhaul network among distributed base stations as well as its latencies. In this paper, we propose a new cloud radio access network architecture based on RF signal soft-switching to solve this problem. Furthermore, we introduce a narrow-band parallel processing technique on a common public radio interface in downlink and uplink to reduce the volume of data as well as the latencies in the transmission process among base band units and remote radio units. By combining theoretical analysis with computer simulations, we show that the technique is valid both for downlink and uplink, i.e., it does not degrade the performance of downlink and uplink propagation between BBU pool and user equipments. Moreover, the computational time of the narrow-band parallel processing technique is less than that of the standard technique.     

基于Doubl-Cluster双集群架构的分布式存储研究

随着大数据时代的临近,面对海量数据的统一存储和管理,传统的网络存储方式DAS、NAS、SAN的瓶颈逐步显现出来,DAS只适用于早期内部少量数据存储,SAN和NAS虽然在存储容量和性能上有了较大提升,但受制因素多,对此文中基于Doubl-Cluster双集群架构,结合并行存储等技术来解决上述问题。事实证明该存储方案能有效消除I/O瓶颈,大幅提高聚合带宽和文件查询效率,保证数据共享。     

一种新的基于光路交换的IP/WDM体系结构设计

本文提出了一种新的基于光路交换的IP业务在WDM上运行的网络体系结构,使用了现有较成熟的、基于光路交换的密集波分复用技术,满足了IP业务的迅速发展对物理层传输带宽的要求,同时从网络结构、网络参考模型、光数据流／光路交换技术以及IP的传输等方面作了详细的分析和阐述。     

基于TCP／IP硬件栈的新型服务器结构

随着大数据时代的到来,基于通用处理器的服务器由于硬件结构的限制,很难在提高性能的同时降低功耗,现提出了一种基于TCP／IP硬件栈的新型服务器架构,将TCP／IP处理流程从通用CPU中分离出来,采用专门的硬件电路实现,在性能与通用服务器相同的情况下,大幅度降低功耗。最后使用FPGA搭建了原型机,并与IBM通用服务器进行了对比测试。     

基于AVS高清编码器IME算法设计和实现

在一个典型的视频编码系统中,其中运动估计(ME)的运算量大约占总运算量的60%~90%,尤其未来的数字电视将以高清和超高清标称,意味着在保持一定的信噪比条件下更大的搜索范围。本文提出了一种基于以上算法优势特点的运动估计算法及其硬件实现――分层全搜索运动估计(HFSME),该算法支持AVS标准的多参考帧技术(B,P帧均采用2幅图像作为参考帧)、率失真优化(RDO)和4种宏块分块模式(16×16,16×8,8×16,8×8),并满足AVS高清实时编码器的需求。从性能上该算法及其硬件实现支持AVS Baseline级高清1080P,帧率达到30 fps,搜索面积达到234×98像素,相较于同样性能下的全搜索算法,峰值信噪比(PSNR)相差不大,但运算量只有全搜索算法运算量的1/4。同时,相较于文献[12]中的结构,本文设计的基于HFSME算法的IME(整像素运动估计)结构设计,在处理单元(PE)规模上是文献[12]结构的2倍,但是搜索范围能力是其4倍,并且吞吐率是其10倍,具有最优的性能,带来了良好的性价比。     

A moving cluster architecture and an intelligent resource reuse protocol for vehicular networks

Real-time data transmission, especially video delivery over high-speed networks have very stringent constraints in terms of network connectivity and offered data rate. However, in high-speed vehicular networks, direct communication between vehicles and road side units (RSU) often breaks down, resulting in loss of information. On the other hand, a peer-to-peer based multihop network topology is not sufficient for efficient data communication due to large packet loss and delay. In this paper, a novel ‘moving cluster multiple forward’ (MCMF) architecture is proposed and investigated for efficient real-time data communication in high speed vehicular networks. MCMF involves novel aspects in relation to the formation of clusters and managing the communication between groups of vehicles and introduction of a hierarchical multiple forwarding mechanism which enables communication between any vehicle and RSU via other vehicles. Additionally, a novel protocol called ‘alternate cluster resource reuse’ (ACRR) is proposed and its detailed communication mechanism is presented. Simulation tests show how the use of MCMF and the ACRR protocol results in superior bit-rate performance—around three times that obtained in peer-to-peer multihop communications and twice that of MCMF with no ACRR protocol. Further, the average delay in MCMF-based transmissions from vehicle to RSU is around 50 % that of a peer-to-peer multihop communication mechanism. MCMF/ACRR has the potential to support multimedia traffic according to the IEEE 802.11p standard, even with a sparse investment in the infrastructure.     

A satellite‐augmented cellular network concept

Some next‐generation personal communication systems propose the use of satellite systems for extending geographical coverage of cellular service. We pursue the idea of using satellite capacity to offload congestion within the area serviced by the terrestrial network. An integrated satellite‐cellular network configuration is considered. The performance of this system is evaluated by means of an analytical model for a one‐dimensional (highway) cellular system overlaid with satellite footprints and by means of simulation for a planar cellular network with satellite spot beam support. Under certain re‐use assumptions, an improvement is found in the blocking performance of the integrated system over the Erlang‐B blocking of a purely cellular circuit switched systems. This is achieved by efficient partitioning (static) of the total bandwidth into space and terrestrial segments. Major factors that influence performance, such as different reuse considerations on the satellite and cellular systems, cell size to footprint size ratios, admission control and call management policies, and changes in traffic patterns, are also investigated. This revised version was published online in June 2006 with corrections to the Cover Date.     

Energy efficiency analysis of heterogeneous cellular network based on Thomas cluster process

In the existing heterogeneous cellular networks (HCN),the rapid increasing of small cells caused a problem that the hotspots where users were clustered generated a huge amount of energy consumption.To improve the energy efficiency of the networks,the spatial model was researched.The users in hotspots in the HCN were modeled as the Thomas cluster process,combined with the max mean bias received signal power (max-BRP) strategy to achieve base station load balancing,and the user’s association probability,coverage probability and the network’s energy efficiency were derived using tool from stochastic geometry.The simulation shows that the derived formulas are accurate,and the network’s energy efficiency can be greatly improved by setting appropriate bias factors.     

一种动态密钥与DNA交错编码的多图像加密算法

针对目前多图像加密算法中置乱效果不佳、DNA编码模式固定及密钥更新方式实用性低等问题,提出了一种基于动态密钥更新与DNA动态交错编码的加密方案。首先,设计了一种利用SHA-256的动态密钥更新方案,通过限制新密钥中的明文信息量摆脱一次一密的密钥系统。其次,改进了三维循环移位置乱方法,并以此降低明文中的相关性。随后,根据混沌序列动态选取DNA编码规则及编码顺序,并在此基础上将图像矩阵逐像素动态交错编码为DNA序列。最后,将编码后的DNA序列与给定序列进行碱基运算完成对明文图像的加密。仿真实验表明,该算法密文图像的相关性可低至10^-3,全局信息熵可达7.999 4。该算法能抵挡各种攻击方式,具有较高安全性。     

基于泰勒级数展开的蜂窝TDOA定位算法

基于用户位置的应用已经成为移动数据业务的重要组成部分,使得蜂窝系统用户定位技术成为蜂窝移动通信领域的研究热点。泰勒级数展开算法因为具有精度高和顽健性强等特点而在求解非线性定位方程组中得到了广泛的应用,但它对初始值有很强的依赖性。本文使用最小二乘方法估计用户位置的初始值并使用泰勒级数展开算法确定用户坐标。通过对算法的仿真分析,结果表明本算法具有近似于基于真实值的泰勒级数展开算法的性能。     

A new design of fault-tolerant digital comparator based on quantum-dot cellular automata

Analog Integrated Circuits and Signal Processing - Quantum-dot cellular automata (QCA) is a new nanoscale development for the future of digital systems. It has been gained a lot of attention since...     

A new homogeneous manipulability measure of robot manipulators, based on power concept

Kinetostatic performance indices have been commonly used for many potential applications in robotics, i.e. optimal design purpose, trajectory planning, manipulation programming, redundancy treatment and dexterity analysis. This has been successful when the mechanism has either fully rotational or translational joints. However, in case of a mechanism having both rotational and translational degrees of freedom; performance indices, such as Jacobian matrix, manipulability or condition number, may not be used due to the dimensional inconsistency with its elements. In this paper, by means of the power concept, a new kinetostatic performance index of robot manipulators is proposed. The power has the same physical units in either translations or rotations. Therefore, we can make use of it as a homogeneous or natural performance index of manipulators. Although it has never been considered as a subject matter of kinetostatic performance criteria, exploiting the behaviour of its basic components namely, force and speed, along the mechanism was likely interesting. On the other hand, the new concept of Oriented Power was introduced, in order to formulate the quadrivector of apparent power, leading to the final homogeneous performance index, which is no longer susceptible to the physical units’ choice. The main benefits of this approach are as follows: firstly there is no need for any restriction on the kinematics’ limits; secondly, the new formalism is insensitive to joint types of mechanism, as well as it has the possibility of grouping translations and rotations of the operational space together. The new index is then both applied in a simple serial mechanism dexterity analysis, and extended to a planar parallel mechanism.     

A new service infrastructure architecture

BT’s planned new architecture defines the technological direction and structure of its future service infrastructure. It provides the template for all service developments and is the key enabler to BT meeting its service vision. This paper summarises the architecture, exploring the key features which will drive the development of BT’s future networks, intelligence and systems.     

A new service infrastructure architecture

BTs planned new architecture defines the technological direction and structure of its future service infrastructure. It provides the template for all service developments and is the key enabler to BT meeting its service vision. This paper summarises the architecture, exploring the key features which will drive the development of BTs future networks, intelligence and systems.     

A new approach for multilevel image segmentation based on fuzzy cellular neural network

A new approach for multilevel image segmentation based on fuzzy cellular neural network(CNN) is proposed. Based on a novel fuzzy CNN, a new template is proposed for multilevel image segmentation. The result of computer simulation proves this approach is reasonable. The stability of the fuzzy neural network is also analyzed in this paper.     

A new binary to gray code converter based on quantum-dot cellular automata nanotechnology

Photonic Network Communications - Quantum-dot cellular automata (QCA) is one of the most prominent technologies in nanometer-scale with appreciable reduction of size and power consumption and high...     

交错并联式并网MATLAB仿真系统研究

对于小型光伏并网发电系统,文中详细分析交错两级式并网系统。直流侧为双重的BOOST升压电路实现最大功率控制,采用扰动观察法实现最大功率点跟踪,并网逆变器的控制策略电压外环电流内环的双环控制,其中电流内环为滞环控制方式,并网逆变器的输出电流跟踪电网电压,实现功率因数为1的并网方式。文中给出了基于MATLAB的系统仿真模型,结果表明光伏电池能较好地实现最大功率点跟踪,电感容量减小,并且逆变后成功并网。     

A new fraction phase based low energy frequency calibration architecture along with an ultra low power VCO design

This paper presents the design and analysis of the architecture of a fraction phase based frequency calibration unit where the number of delay cells (that sense the fraction phase) have been reduced to zero. As no pre-calibration of the delay values are required, it becomes immune to process-voltage-temperature variation. Simulation results for frequency convergence have been provided for different target frequencies of an LC oscillator and for an accuracy of 400 ppm. The paper next presents the design and analysis of a voltage controlled oscillator in the form of an astable multivibrator that is similar to a single stage ring oscillator. A novel resistive tuning technique that occupies small chip area and provides less process variation and more matching has been proposed. Also, it has been shown that although the oscillator’s phase noise is worse than LC oscillator, the frequency convergence probability (when using the frequency calibration unit with 4 delay cells, due to the high jitter values) does not degrade significantly with the same calibration unit specifications. Hence successful integration of the oscillator with the calibration unit is possible with the advantage of having fully on-chip design with lower power consumption than that of LC oscillators. The oscillator and the calibration circuit have been designed in UMC 180 nm technology that together consume a current of 320µA (in simulation) from 1.6 V power supply. The designs have been targeted for implant telemetry in the 402–405 MHz band having the requirement of ultra low power consumption.

     

A cellular computing architecture for parallel memristive stateful logic

We present a cellular memristive stateful logic computing architecture and demonstrate its operation with computational examples such as vectorized XOR, circular shift, and content-addressable memory. The considered architecture can perform parallel elementary memristor programming and stateful logic operations, namely implication and converse nonimplication. The topology of the crossbar structure used for computing can be dynamically reconfigured, enabling combinations of local and global operations with varying granularity. In the CMOS cells used for controlling the memristors, we apply a new type of capacitive keeper circuit, which allows for energy efficient implementation of logic operations. The correct operation of this architecture is verified by detailed HSPICE simulations for a structure containing eight memristive crossbars. This work presents a hardware platform which enables future work on parallel stateful computing.