Group based DBF MUD in CDMA mobile communication system

For the CDMA wireless cellular communication system, a new methodology is proposed to combine digital beamforming (DBF) with multi user detection (MUD) technology which harnesses the co channel interference mitigation and obtains better performance. The proposed approach assigns all the users within a cell into separated groups according to their direction of arrival (DOA). Then, only one DBF branch is employed for a singular group so that the main lobe is steered to the desired users in the group and nulls are directed to the mobile stations in other group. Furthermore, inter group interference is degraded by MUD following the DBF. The new strategy simplifies the weight vector calculation and solves the unorthogonal channel problem. Additionally, it decreases the bit error rate. The analysis and simulation illustrate the fruits of the new mechanism.     

A Data Detector Based on Channel Equalizer Designed for the Downlink of CDMA Systems

In code-division multiple-access (CDMA) systems,sub-optimum multi-user or joint detection algorithms have been studied recently, which are mostly designed for the uplink situation. The algorithms are too complex to implement for the downlink situation. The conventional receiver consisting of matched filters is often inefficient in eliminating MAI. The authors propose a data detection algorithm designed for downlink of CDMA systems which introduce channel equalization to eliminate MAI. It consists of a channel equalizer and code matched filter. The equalization algorithm is based on zero forcing (ZF) criterion.The performance of the algorithm is better than metched filter's and its complexity is cower than tunt of sub-optimum multi-user detection.     

Research on the improvement of the convergencespeed for CDMA system power control

Optimal power control with game-theory has been a hot research topic in code division multiple access (CDMA) system. However, the convergence speed of the power control algorithm based on traditional static game-theory is not fast enough and the power fluctuation is large during the iterative process. In order to solve this problem, dynamic game-theory is introduced into CDMA system power control algorithm. The simulation results show that the proposed algorithm, compared with the distributed power control algorithm based on the traditional static game theory, can improve the convergence speed obviously with the same power spending.     

A blind adaptive reduced-rank receiver for ultra-wideband communication systems

A low-complexity blind adaptive receiver for ultra-wideband (UWB) systems in the presence of both multiple access interference (MAI) and inter symbol interference (ISI) is proposed, which is composed of two stages. In the first stage, a reduced-rank algorithm based on the multi-stage Wiener filter (MSWF) is considered to suppress the MAI and extract multi-path components. Channel estimation using the projection approximation subspace tracking with deflation (PASTd) algorithm and multi-path combining are then performed to further enhance the signal to interference plus noise ratio (SINR) of the desired user in the second stage. The simulation results show that the proposed receiver exhibits reasonably good bit error ratio (BER) performance compared with those of matched filter, conventional Rake receiver, decorrelating Rake receiver and adaptive receiver based on constant modulus algorithm (CMA). Moreover, it has faster convergence speed and less complexity.     

Algorithm Discussion of High Precision for Wireless User Location

In recent years , because of increasing mobile users ,the wireless location and business is the most attractive business in the world , accurate location information to users has become one of criterion business for mobile communication ,so a discussed deeply wireless location technology is very value. This paper discusses it from high accuracy algorithm for wireless location on the network , by the emulation and comparison, it has shown that there are different algorithms in different surroundings for arriving at satisfied precision     

基于微信公众平台的枣树病虫害专家诊断系统开发

为快速传播并普及枣树病虫害知识,使用农业专家系统提高枣树病虫害诊断及管理效率,基于微信服务号公众平台,采用php脚本语言及mysql数据库开发出枣树病虫害专家诊断系统"JujubaExpert2020".该系统包括病虫诊断、栽培历史及枣树资讯3个功能模块,核心功能为枣树主要病虫害数据库和专家诊断论坛.用户可以通过关键字...     

农业信息网站服务质量评价指标优化研究

提高农业信息网站服务质量是有效解决农业信息化发展瓶颈的方法之一。科学的网站服务质量评价,可以提高用户获取信息的效率,同时网站设计者通过了解影响其服务质量的主要因素,可以优化网站资源配置。笔者参考服务质量管理的有关原理和已有的指标设计方法,构建了一个农业信息网站服务质量评价通用模型,利用R型系统聚类法探索描述性指标项优化问题,以避免指标项之间存在的相关、重复情况,最后以40个茶叶信息网为实验对象进行数据采集与分析,构建农业信息网站服务质量评价影响因素的多元回归模型,得出在信息服务系统构建过程中影响信息服务质量的重要因素。     

Waiting for Broadband: Local Competition and the Spatial Distribution of Advanced Telecommunication Services in the United States

ABSTRACT With the passage of the Telecommunications Act of 1996, Congress directed the Federal Communications Commission and all fifty U.S. states to encourage the deployment of advanced telecommunication capability in a reasonable and timely manner. Today, with the rollout of advanced data services such as digital subscriber lines (xDSL), cable modems, and fixed wireless technologies, broadband has become an important component of telecommunication service and competition. Unfortunately, the deployment of last‐mile infrastructure enabling high‐speed access has proceeded more slowly than anticipated and competition in many areas is relatively sparse. More importantly, there are significant differences in the availability of broadband services between urban and rural areas. This paper explores aspects of broadband access as a function of market demand and provider competition. Data collected from the Federal Communications Commission is analyzed using a geographic information system and spatial statistical techniques. Results suggest significant spatial variation in broadband Internet access as a function of provider competition in the United States.     

Multi-Step Iterative MUD Technology for TD-SCDMA System

Joint Detection technology is a hot point in the research of TD-SCDMA system. Because of a SNR degradation, JD can not reach the need of system performance when system loads is close to the spread factor. MSJD and iterative multi-user detection are put forth to overcome the problem. When iterative MUD is adopted, the research shows that system performance is close to single user performance after 3 iterations, but its computational complexity grows exponentially with the number of code channel. When MSJD is adopted, complexity is reduced compared with iterative MUD, but system performance of code channels numbered K is only close to system performance of code channels numbered K/2 as JD is used. Considering computational complexity and system performance, multi-step iterative multi-user detection technology is brought forth based on iterative MUD and MSJD. According to simulation, the result can be concluded that complexity is reduced compared with single iterative MUD and system performance is improved compared with single MSJD.     

Direction of Arrival Estimation for CDMA Communication Signal

MUSIC algorithm is often applied in direction of arrival estimation of communication signal or radar signal. But the traditional MUSIC algorithm is not applicable in the presence of the correlational signals. Combining with time average processing, an algotithm of two-dimensional space-time average is suggested on the base of space average technic especially for the DOA estimation of CDMA communication signal. A detaild analysis and a conclusion about this improved algorithm is presented. Ensuring the accurary of the estimation an efficient decrease in quantity of operation is achieved with the algorithm, so it is more suitable for real-time processing. The efficiency of the improved algorithm is attested by the emulating results.     

Performance Analysis of Anti-CW Interference in MC-CDMA Systems

The multicarrier-code division multiple access (MC-CDMA),which is the combination of direct sequence CDMA (DS-CDMA) and orthogonal frequency division multiplexing (OFDM) techniques, offers various advantages over single-carrier CDMA system. Some of the advantages are that MC-CDMA systems possess can remove the intersymbol interference (ISI) and enhance narrow-band interference suppression capabilities. So the MC-CDMA technique becomes a focus in the field of mobile communication. The authors introduce the typical MC-CDMA system model, discuss the decision statisticalvariable in Rayleigh fading channel included the CW interference, and give the expressions of probability of error in uplink. An approach is proposed with Modified Equal Gain Combining (MEGC) to decrease the effect of CW interference. Theoretical analysis and numerical results show that the anti-CW interference performance of MC-CDMA system can be improved used the MEGC approach.     

Topological characteristics of industry collaborative production networks

It is an important way for co production efficiency improvement and system robustness to deeply understand the relationship between the structure and function of interfirm collaborative production networks (ICPN) . This paper develops the topological model for ICPN based on the analysis of the characteristics of interfirm collaborative production modes. By introducing complex networks, a case of Polyurethane industry is simulated. The results show that ICPN has the characteristics of small world, scale free and centralities of nodes. Moreover, complex network characteristics affect the capability and efficiency of production system.     

Study on Broadband Cellular Mobile Communication System OFDM Based

The characteristic of broadband mobile channel is analyzed, then we construct a model of bidimensions wideband mobile channel based on delay and Doppler frequency domain. On the basis of describing OFDM theory, the design on initial physical layer of broadband cellular mobile communication systems is proposed. Simulation for base band system is ground on channel model proposed above. The results of experiment and simulation are relatively inosculated, which manifest the well prospect of the communication system proposed for future application.     

酵母表面展示系统的改进及其在筛选烟草PMT基因启动子结合蛋白中的应用

筛选DNA结合蛋白常用的酵母单杂交系统在应用中有时会因内源干扰而影响筛选结果。与之相比,酵母表面展示系统(yeast surface display system)将外源蛋白展示在细胞表面,可通过接近体外实验的方法筛选DNA结合蛋白,能在一定程度上避免酵母内源干扰,但是,该系统在DNA结合蛋白筛选研究中的应用还很有限。本研究对酵母表面展示系统常用载体pYD1进行改造,使其与Clontech公司的Smart cDNA文库构建系统相匹配,提高了cDNA酵母表面展示文库的构建效率,并通过比较试验建立了一个以酵母表面展示系统筛选DNA结合蛋白的试验体系。在以酵母单杂交筛选烟草腐胺甲基转移酶基因PMT (putrescine N-methyltransferase)启动子结合蛋白的研究中,其茉莉素信号应答元件GAG片段是一段筛选效率极低的DNA片段。本研究利用改进的酵母表面展示系统对GAG片段的DNA结合蛋白进行了筛选,并获得若干烟草蛋白基因,其中包括2个可能结合GAG片段的ERF (ethylene responsive factor)转录因子。进一步研究发现,这2个ERF转录因子可与GAG片段在体外结合,但不能在酵母单杂交系统中激活由GAG片段操纵的报告基因表达。本研究也证明酵母表面展示系统可有效克服酵母内源干扰,弥补酵母单杂交系统在筛选易受酵母内源干扰DNA结合蛋白方面的不足。     

Target-based Security Management Architecture Applied to Management Information System

In order to implement the security management of management information system (MIS), a target-based security management architecture is proposed. For MIS users, the user interface (UI) is the only way to interact with the MIS system, so all the objects (targets) which need to be managed on UI is registered first, thus for every target the state such as enabled, not enabled, visible, not visible, readonly etc., is assigned. For some users, a set of targets with some state is assigned so that the management granularity in MIS can reach any degree. This approach provides a very flexible way to the security management in MIS.     

Patterns of Broadband Efficiency in the U.S

Data envelopment analysis is used to assess the efficiency of broadband Internet adoption and use in the U.S. Analyses at the state level from 2005 to 2007 suggest that broadband adoption and use is not equally efficient across the U.S. states. Although the instantaneous efficiencies are relatively high for many states, the changes in total factor productivity suggest that the efficiency of broadband adoption and use still increases over time. Moreover, it is observed that efficiency values are often spatially autocorrelated, which suggests spatial dependency from spillovers or interstate competition. This leads to a particular spatial diffusion pattern in broadband adoption. Although states have different strategies in support of broadband expansion they need to identify their shortcomings and use the appropriate mix of inputs (and outputs) to improve their efficiencies.     

2001—2010年河南省县域农业生产效率动态分析

运用数据包络分析(DEA)模型对河南省108 个县域2001—2010 年的农业生产效率进行分析,获得了各县域的纯技术效率、规模效率和综合技术效率,对各县农业生产效率的时空动态进行了分析。结果表明：河南省各县域纯技术效率有效的地区在增加,总体纯技术效率明显增加;大多数县域的农业生产规模效率已达到较优水平,但规模效率有效的地区还很有限,还存在一定的增长空间,总体规模效率有所下降;河南省农业生产综合效率基本保持稳定,但各县域的波动较大。这说明河南省在2001—2010 年间对农业的技术投入有显著增加,正在有效弥补过去技术效率水平较低的“短板”,其综合技术效率仍有较大的提高空间。     

Broadband Access Network Based on Ethernet Technology

With development of broadband network application, the accessing technology of broadband network becomes an active area. Some accessing technologies, such as ADSL and HFC, have been used. But these methods do not be used widely due to their high costs. The authors discuss the widely used Ethernet technology and show how it can be deployed in broadband access network, addressing some problems need to face. Several solutions will be given, and conclusions are drawn.     

Analysis of Loosely Coupled Inductive Power Transfer System

In LCIPT system, the selection of system operation frequency has a relationshi Pwith the cost and power transfer capability of the power supply. Due to the development of Power device and system efficiency requirement , it is restricted to increase the system operation frequency . This paper presentes a topology which transfers power through LC oscillation. When the voltage of the capacitor is less than reference voltage, the switch is turned off and the capacitor is charged, which makes the switching frequency far less than the syntonic frequency. Thus the system efficiency is improved, and the system cost is reduced. This is verified by the time domain and frequency domain simulations of Saber. This topology not only can be used in LCIPT, but also in other convertors.     

A System Dynamics Model of Rural Eletrification in Small-Hydroelectric Area

In present paper, a system dynamics model of Rural electrification in small-hydroelectric area was designed by using the principle of system dynamics. The model provides a scientific basis for computer emulation and simulation, and it can be used to analyze the policies on rural electrification.