A multiple access protocol is proposed to greatly improve multiple access performance of wireless networks with long propagation delay. All the nodes with packets to send can make rapid successful reservation in acces...A multiple access protocol is proposed to greatly improve multiple access performance of wireless networks with long propagation delay. All the nodes with packets to send can make rapid successful reservation in access reservation mini-slots, which is adaptively adjusted according to current traffic load and idle channel resources. A Central Control Node (CCN) coordinates channel reservation and allocates on-demand channel resources to the successfully accessed nodes on two channels. Each node can employ only one handshake to accomplish each communication session, and transmit one or multiple data packets piggybacked with acknowledgment (ACK) information to one or multiple destination nodes in each frame until the end of their communication sessions, which greatly minimizes the impact of long propagation delay caused by handshakes and improves channel efficiency. Simulation results show that the proposed protocol obviously outperforms the Centralized Scheduling-based Medium Access Control (CSMAC) protocol, especially in the presence of long propagation delay.展开更多
In CDMA communication systems, all the subscribers share the common channel. The limitation factor on the system’s capacity is not the bandwidth, but multiuser interference and the near far problem. This paper models...In CDMA communication systems, all the subscribers share the common channel. The limitation factor on the system’s capacity is not the bandwidth, but multiuser interference and the near far problem. This paper models CDMA system from the perspective of mobile radio channels corrupted by additive white noise generated by multipath and multiple access interferences. The system’s receiver is assisted using different combining diversity techniques. Performance analysis of the system with these detection techniques is presented. The paper demonstrates that combining diversity techniques in the system’s receivers markedly improve the performance of CDMA systems.展开更多
This paper proposes a new multi-stage parallel interference cancellation scheme by modifying the conventional multi-stage parallel interference canceller (PIC). At each stage, it first converts the interference-cancel...This paper proposes a new multi-stage parallel interference cancellation scheme by modifying the conventional multi-stage parallel interference canceller (PIC). At each stage, it first converts the interference-cancelled outputs from previous stage into thea prior information, in terms of which the bit mean values are computed and the multi-access interference (MAI) for each user is evaluated, and then an interference cancellation is performed to obtain further interference suppression. To reduce the implementation complexity, we give an approximation expression for bit mean value. The performance over AWGN channel is analyzed and compared to the conventional PIC. The user numberK=7 and spreading factorN=13 are chosen as simulation parameters. The computer simulation results show that the proposed PIC has better performance than the conventional PIC both with 2 interference cancellation (IC) stages, at bit error rate of 10?3, for example, about 3 dB performance gain is obtained by using the proposed PIC. It is also shown that our proposed PIC with 1-stage is superior to the conventional PIC with 2-stage in performance, which is of practical value because PIC with fewer stages can bring about shorter processing delay. Key words CDMA - parallel interference cancellation - multi-access interference CLC number TN 914 Foundation item: Supported by the National Natural Science Foundation of China (69772015)Biography: Xu Guo-xiong (1967-), male, Ph. D candidate, research direction: wireless communication.展开更多
A two-stage soft parallel interference cancellation (SPIC) algorithm in WCDMA system is proposed. The performance of the algorithm is analysed in perfect power control and near-far case, and the influence of the timin...A two-stage soft parallel interference cancellation (SPIC) algorithm in WCDMA system is proposed. The performance of the algorithm is analysed in perfect power control and near-far case, and the influence of the timing error on the system BER is discussed. Analysis and simulation show that the SPIC technique can enhance system capacity, and have a good ability to resist near-far impact. With its simple structure, it has good potential for practical applications.展开更多
随着SoC的复杂度不断提高,通过集成IP核的设计方式能够加快芯片设计的周期,同时由于总线上主从设备的增加,有必要基于AHB总线设计一款高速互连的AHB总线矩阵,在AHB multi layer的基础上,将仲裁模块改为由内部寄存模块接收信息后,再由从...随着SoC的复杂度不断提高,通过集成IP核的设计方式能够加快芯片设计的周期,同时由于总线上主从设备的增加,有必要基于AHB总线设计一款高速互连的AHB总线矩阵,在AHB multi layer的基础上,将仲裁模块改为由内部寄存模块接收信息后,再由从机端完成对各个主机发送过来的信号信息进行仲裁。同时还加入了防死锁模块,从而实现了能够根据预设的计数阈值判断AHB是否发生死锁的功能;最后通过AHB总线接口的验证IP搭建UVM仿真测试环境,对所设计的总线系统基本功能进行了测试,实现了单master访问多个slave和多个master对多个slave并行访问的功能。展开更多
近似串匹配技术在网络信息搜索、数字图书馆、模式识别、文本挖掘、IP路由查找、网络入侵检测、生物信息学、音乐研究计算等领域具有广泛的应用.基于CREW-PRAM(parallel random access machine with concurrent read and exclusive wri...近似串匹配技术在网络信息搜索、数字图书馆、模式识别、文本挖掘、IP路由查找、网络入侵检测、生物信息学、音乐研究计算等领域具有广泛的应用.基于CREW-PRAM(parallel random access machine with concurrent read and exclusive write)模型,采用波前式并行推进的方法直接计算编辑距离矩阵D,设计了一个允许k-差别的近似串匹配动态规划并行算法,该算法使用(m+1)个处理器,时间复杂度为O(n),算法理论上达到线性加速;采取水平和斜向双并行计算编辑距离矩阵D的方法,设计了一个使用a(m+1)个处理器和O(n/a+m)时间的、可伸缩的、允许k-差别的近似串匹配动态规划并行算法,+<11mna.基于分治策略,通过灵活拆分总线和合并子总线动态重构光总线系统,并充分利用光总线的消息播送技术和并行计算前缀和的方法,实现了汉明距离的并行计算,设计了两个基于LARPBS(linear arrays with reconfigurable pipelined bus system)模型的通信高效、可扩放的允许k-误配的近似串匹配并行算法,其中一个算法使用n个处理器,时间为O(m);另一个为常数时间算法,使用mn个处理器.展开更多
基金supported by National Science Foundation for Innovative Research Groups of China under Grant No.60921001National Natural Science Foundation of China under Grant No.60933012+2 种基金National Science and Technology Major Project of China under Grant No.2009ZX03006-001-003, 2010ZX03003-003-03China Fundamental Research Funds for the Central Universities under Grant No.YWF-10-01-A16NSBS Program of Beihang University,China under Grant No.221235
文摘A multiple access protocol is proposed to greatly improve multiple access performance of wireless networks with long propagation delay. All the nodes with packets to send can make rapid successful reservation in access reservation mini-slots, which is adaptively adjusted according to current traffic load and idle channel resources. A Central Control Node (CCN) coordinates channel reservation and allocates on-demand channel resources to the successfully accessed nodes on two channels. Each node can employ only one handshake to accomplish each communication session, and transmit one or multiple data packets piggybacked with acknowledgment (ACK) information to one or multiple destination nodes in each frame until the end of their communication sessions, which greatly minimizes the impact of long propagation delay caused by handshakes and improves channel efficiency. Simulation results show that the proposed protocol obviously outperforms the Centralized Scheduling-based Medium Access Control (CSMAC) protocol, especially in the presence of long propagation delay.
文摘In CDMA communication systems, all the subscribers share the common channel. The limitation factor on the system’s capacity is not the bandwidth, but multiuser interference and the near far problem. This paper models CDMA system from the perspective of mobile radio channels corrupted by additive white noise generated by multipath and multiple access interferences. The system’s receiver is assisted using different combining diversity techniques. Performance analysis of the system with these detection techniques is presented. The paper demonstrates that combining diversity techniques in the system’s receivers markedly improve the performance of CDMA systems.
文摘This paper proposes a new multi-stage parallel interference cancellation scheme by modifying the conventional multi-stage parallel interference canceller (PIC). At each stage, it first converts the interference-cancelled outputs from previous stage into thea prior information, in terms of which the bit mean values are computed and the multi-access interference (MAI) for each user is evaluated, and then an interference cancellation is performed to obtain further interference suppression. To reduce the implementation complexity, we give an approximation expression for bit mean value. The performance over AWGN channel is analyzed and compared to the conventional PIC. The user numberK=7 and spreading factorN=13 are chosen as simulation parameters. The computer simulation results show that the proposed PIC has better performance than the conventional PIC both with 2 interference cancellation (IC) stages, at bit error rate of 10?3, for example, about 3 dB performance gain is obtained by using the proposed PIC. It is also shown that our proposed PIC with 1-stage is superior to the conventional PIC with 2-stage in performance, which is of practical value because PIC with fewer stages can bring about shorter processing delay. Key words CDMA - parallel interference cancellation - multi-access interference CLC number TN 914 Foundation item: Supported by the National Natural Science Foundation of China (69772015)Biography: Xu Guo-xiong (1967-), male, Ph. D candidate, research direction: wireless communication.
文摘A two-stage soft parallel interference cancellation (SPIC) algorithm in WCDMA system is proposed. The performance of the algorithm is analysed in perfect power control and near-far case, and the influence of the timing error on the system BER is discussed. Analysis and simulation show that the SPIC technique can enhance system capacity, and have a good ability to resist near-far impact. With its simple structure, it has good potential for practical applications.
文摘随着SoC的复杂度不断提高,通过集成IP核的设计方式能够加快芯片设计的周期,同时由于总线上主从设备的增加,有必要基于AHB总线设计一款高速互连的AHB总线矩阵,在AHB multi layer的基础上,将仲裁模块改为由内部寄存模块接收信息后,再由从机端完成对各个主机发送过来的信号信息进行仲裁。同时还加入了防死锁模块,从而实现了能够根据预设的计数阈值判断AHB是否发生死锁的功能;最后通过AHB总线接口的验证IP搭建UVM仿真测试环境,对所设计的总线系统基本功能进行了测试,实现了单master访问多个slave和多个master对多个slave并行访问的功能。
文摘近似串匹配技术在网络信息搜索、数字图书馆、模式识别、文本挖掘、IP路由查找、网络入侵检测、生物信息学、音乐研究计算等领域具有广泛的应用.基于CREW-PRAM(parallel random access machine with concurrent read and exclusive write)模型,采用波前式并行推进的方法直接计算编辑距离矩阵D,设计了一个允许k-差别的近似串匹配动态规划并行算法,该算法使用(m+1)个处理器,时间复杂度为O(n),算法理论上达到线性加速;采取水平和斜向双并行计算编辑距离矩阵D的方法,设计了一个使用a(m+1)个处理器和O(n/a+m)时间的、可伸缩的、允许k-差别的近似串匹配动态规划并行算法,+<11mna.基于分治策略,通过灵活拆分总线和合并子总线动态重构光总线系统,并充分利用光总线的消息播送技术和并行计算前缀和的方法,实现了汉明距离的并行计算,设计了两个基于LARPBS(linear arrays with reconfigurable pipelined bus system)模型的通信高效、可扩放的允许k-误配的近似串匹配并行算法,其中一个算法使用n个处理器,时间为O(m);另一个为常数时间算法,使用mn个处理器.
