分离缓存窗口访问机制调度算法研究

窗口访问机制是克服队首阻塞的一种有效策略。本文提出一种新的基于分离缓存思想的窗口调度算法，并与其它三种性能较优的窗口机制调度算法就吞吐率性能及实现复杂度进行了分析和比较，仿真结果验证了新算法在均匀和突发业务下性能均优于其它算法。     

宽带固定无线接入技术及市场分析

本文综述了当前几种发展极为迅速的宽带固定无线接入技术，讨论了其演变过程及在国内的发展现状，并总结了无线接入在未来的主要发展趋势。     

大客户融合通信业务接入应用研究

对大客户的融合通信业务需求特点进行了分析,探讨了相关技术在大客户融合通信接入中的应用场景和发展趋势,并对大客户融合通信业务接入建设模式进行了分析。     

A novel multicarrier index keying-aided non-orthogonal multiple access systems in presence of uncertain channel state information

This paper investigates the performance of novel multicarrier index keying-aided non-orthogonal multiple access (MCIK-NOMA) system. Unlike the classical scheme, the proposed system sends the information through both index domain and constellation domain symbols thereby increases the spectral efficiency. The impact of channel state information (CSI) uncertainty on the system's performance is investigated. More specifically, the performance of MCIK-NOMA under three different CSI conditions is analyzed: perfect CSI, MMSE-based variable CSI, and fixed CSI uncertainty. This paper also discusses the optimum power difference needed for the successful separation of symbols at the SIC receiver by alternating the power ratio in the proposed system. The influence of selecting different active subcarriers and modulation techniques on the system's performance is studied in detail. The simulation results show that the proposed system achieves better BER and spectral efficiency and outperforms the existing systems.     

Effect of multipath fading and multiple access interference on broadband code division multiple access systems

In this paper, the performance of uncoded uplink transmissions in a broadband code division multiple access (CDMA) system using tapped delay line (TDL) antenna array under multipath conditions is investigated. An expression for broadband CDMA system is derived to calculate the optimal weights of TDL antenna array. Using the derived broadband expression, the performance of TDL antenna array is investigated and compared with that of the already existing narrowband systems. Simulation results show that TDL antenna array can reduce multipath fading and multiple access interference (MAI). It is shown that if the signal‐to‐noise ratio (SNR) level is maintained at 20 dB and two‐ray channel model is used, two antennas with four taps each can support 30 users with a BER of 10^?3. If three‐ray channel model is used, the same antenna arrangement is not enough to support 30 users. To support these 30 users with BER of 10^?3, the number of taps needs to be increased to eight. Finally, the number of taps needs to be further increased to 16 if four‐ray channel model is used. Not only that, the SNR should also be increased to 25 dB to achieve the same BER. Copyright © 2011 John Wiley & Sons, Ltd.     

Design and fabrication of a planar patch-clamp substrate using a silicon-on-insulator wafer

noise.     

改进的RBAC在设备管理系统中的应用

基于角色访问控制(RBAC)是一种方便安全和高效的访问控制机制,但对操作主体的设量最小粒度只能达到角色级别,造成系统的灵活性与实用性不足.针对这个缺陷,在设备管理系统中,首先对系统的权限进行层次式划分,系统角色实行等级制,上级角色给下级角色设置权限,使操作主体最小粒度达到单个用户,对权限的表示采用了权限特征值的方法,减...     

On Multirate DS-CDMA Schemes with Interference Cancellation

This paper investigates interference cancellation (IC) in direct-sequence code-division multiple access (DS-CDMA) systems that support multiple data rates. Two methods for implementing multiple data rates are considered. One is the use of mixed modulation and the other is the use of multicodes. We introduce and analyze a new approach that combines these multiple data rate systems with IC. The cancellation in the receiver is performed successively on each user, starting with the user received with the highest power. This procedure can in turn be iterated, forming a multistage scheme, with the number of iterations set as a design parameter. Our analysis employs a Gaussian approximation for the distribution of the interference, and it includes both the AWGN and the flat Rayleigh fading channel. The systems are also evaluated via computer simulations. Our analysis and simulations indicate that the IC schemes used in mixed modulation or multicode systems yield a performance close to the single BPSK user bound and, consequently, give a prospect of a considerable improvement in performance compared to systems employing matched filter detectors.     

地铁中的移动通信系统

提出了地铁专用移动通信系统的功能要求；介绍和分析了一个满足系统功能要求的集群方案；另外还简单介绍了地铁公用移动通信引入系统。     

IP接入网

文章给出了IP接入网的定义、功能体系,介绍了IP用户终端和ISP链路层协议,重点讨论了适于支持IP接入的几种方式。