LTE-A空口监测分析仪中PDSCH解资源映射的设计与实现

针对增强型长期演进（LTE-A）物理层传统解资源映射方法中重复计算资源映射位置造成的计算量冗余问题,提出一种新型架构的物理下行共享信道（PDSCH）解资源映射方法,为LTE-A空口监测分析仪相关物理层处理提供支持。首先,在物理层下行信号和信道解资源映射之前,产生单天线端口0模式、发射分集模式、单流波束赋形以及双流波束赋形下各个信号和信道的资源索引;然后,在物理层解资源映射时根据资源索引直接定位各信号和信道资源的时频位置;最后,把PDSCH信道解资源映射模块放在整个LTE-A链路级仿真平台中,给出四种传输模式下的仿真,得出不同传输模式下的误码率以及吞吐量的对比图,为最终的硬件实现提供理论参考。同时通过与传统架构下的解资源映射模块进行对比表明,该新型架构下的解资源映射模块比传统架构下的解资源映射仿真所花费的时间减少了33.33%,降低了解资源映射时的运算量和设备资源消耗。     

基于功率控制的LTE系统下行ICIC算法研究

在LTE系统中,小区的边缘用户会同时受到邻区同频用户的干扰,需要一种小区间的干扰协调技术（ICIC）来解决这个问题。分析传统ICIC算法的不足,提出一种优化的算法,通过计算边缘用户在单个干扰用户和多个干扰用户情况下的容量,得出邻区基站较为精确的发射功率控制量。参考3GPP标准案例仿真模型,对该算法进行了仿真,仿真结果表明与传统ICIC算法的相比,该算法可以明显提高边缘用户的吞吐量。     

基于半正定松弛的MIMO系统下行链路预编码方案

多用户多输入多输出系统下行链路中,信漏噪比最大化的预编码方法的发射功率控制方式并不能有效保证用户可达的信漏噪比,该文提出追求信漏噪比约束下最小化发射总功率的预编码器设计方案。利用半正定松弛的方法对目标问题可以进行有效地求解,并且在设计目标中增加功率约束条件,能有效降低基站的发射总功率。仿真结果显示相比于信漏噪比最大化方法,该文提出的方案在满足较大的信漏噪比门限时具有更好的系统误码性能和更低的发射总功率,并且随着信噪比的增加,其发射总功率不断降低。     

高阶调制技术在LTE网络中的研究及应用

为了进一步提升LTE网络无线空口容量,对LTE-A中的高阶调制技术进行研究及应用验证.理论上,上行16 QAM到64 QAM可提升50%的速率,下行64 QAM到256 QAM可提升33%的速率.本文通过实测对比验证了高阶调制的效果,而且无线环境越好,速率增益效果越明显.     

基于相关检测的低复杂度窄带物理下行控制信道盲检测算法

在窄带物联网系统（NB-IoT）中,物联网（IoT）终端应当快速获取下行控制信息（DCI）,以便正确接收数据信道的资源分配和调度信息。为此,针对窄带物理下行控制信道（NPDCCH）搜索空间大小大于等于32时,提出一种利用相关检测的低复杂度的NPDCCH盲检测算法。首先,通过对一个NPDCCH可能最小重复传输单元进行两次相关判决,剔除搜索空间中其他无效的数据,以降低计算复杂度;然后,对判决为有效数据所在的重复周期进行合并译码,以提高盲检性能;最后,对两个相关阈值设定进行了理论与仿真分析。仿真结果表明,相比穷举盲检测算法,所提算法在计算复杂度上至少降低了75%,检测性能提高了增益2.5~3.5 dB,更加利于工程实践。     

Scheduling for time-division based shared channel allocation for UMTS

The Universal Mobile Telecommunications System (UMTS) adopts the WCDMA technology as the radio access interface to provide variable transmission rate services. There are four classes of connections identified in UMTS, which are the conversational, streaming, interactive, and background connections. To efficiently utilize radio bandwidth, the shared channel approach is proposed to deliver the packets for the interactive and background connections. This paper proposes a “Shared-Channel Assignment and Scheduling” (SCAS) algorithm to periodically allocate shared channels to serve interactive and background connections. We conduct formal mathematical proofs and simulation experiments to investigate the performance of the SCAS algorithm. We formally prove that with SCAS, a shared channel can be fully utilized (i.e., the utilization of a shared channel can be up to 100%) to serve the interactive connections. Our analysis indicates that compared with the previously proposed shared channel allocation and scheduling algorithms, there are less computation and communication overheads introduced in the SCAS algorithm. The results of the simulation experiments indicate that it is preferred to set up the Transmission Time Interval (TTI; that is, the unit of time interval for shared channel allocation) smaller to optimize the performance of the SCAS algorithm, including the shared channel utilization and the average waiting time of a connection before getting transmission service. A preliminary version [11] of this work has been accepted by IEEE Wireless Communications and Networking Conference 2004. This paper is an extension of the proposed algorithm, and simulation and analysis are conducted to investigate the performance of the proposed algorithm. Chai-Hien Gan was born in Malaysia in 1971. He received his BS degree in computer science from Tamkang University in 1994, Taipei County, Taiwan, and both his MS. and Ph.D. degrees in computer science and information engineering from National Taiwan University, Taipei, Taiwan, in 1996 and 2005, respectively. Since March 2005, he has been a Research Assistant Professor in Department of Computer Science, National Chiao Tung University, R.O.C. His current research interests include wireless mesh networks, mobile computing, personal communications services, and wireless Internet. Phone Lin received his BSCSIE degree and Ph.D. degree from National Chiao Tung University, Taiwan, R.O.C. in 1996 and 2001, respectively. From August 2001 to July 2004, he was an Assistant Professor in Department of CSIE and Graduate Institute of Graduate of Networking and Multimedia, National Taiwan University, R.O.C. Since August 2004, he has been an Associate Professor in Department of CSIE and Graduate Institute Graduate of Networking and Multimedia, National Taiwan University, R.O.C. His current research interests include personal communications services, wireless Internet, and performance modeling. Dr. Lin is an Associate Editor for IEEE Transactions on Vehicular Technology, Editor for IEEE Wireless Communications special issue on Mobility and Resource Management and a Guest Editor for ACM/Springer MONET special issue on Wireless Broad Access. He is also an Associate Editorial Member for the WCMC Journal. P. Lin’s email and website addresses are plin@csie.ntu.edu.tw and http://www.csie.ntu.edu.tw/~plin, respectively. Nei-Chiung Perng is presently a Ph.D. student in the Department of Computer Science and Information Engineering, National Taiwan University. He received his Bachelor and Master degrees in the Department of Computer and Information Science, National Chiao Tung University in 1999 and 2001, respectively. His research interests include real-time systems and scheduling algorithms. Tei-Wei Kuo received B.S.E. degree in computer science and information engineering from National Taiwan University in Taipei, Taiwan, in 1986. He received the M.S. and Ph.D. degrees in computer sciences from the University of Texas at Austin in 1990 and 1994, respectively. He is currently a Professor and the Chairman of the Department of Computer Science and Information Engineering of the National Taiwan University, Taiwan, ROC. He was an Associate Professor in the Department of Computer Science and Information Engineering of the National Chung Cheng University, Taiwan, ROC, from August 1994 to July 2000. Dr. Kuo is a senior member of the IEEE computer society. His research interest includes embedded systems, real-time process scheduling, real-time operating systems, and real-time databases. He has over 100 technical papers published or been accepted in international journals and conferences and has a book “Real-Time Database Systems: Architecture and Techniques” published by Kluwer Academic Publishers (ISBN 0-7923-7218-2, USA). He is the Program Co-Chair of IEEE 7th Real-Time Technology and Applications Symposium, 2001, and an associate editor of the Journal of Real-Time Systems since 1998. He is an executive committee member of the IEEE Technical Committee on Real-Time Systems in 2005 and the steering committee chair of IEEE RTCSA’05. Dr. Kuo has consulted for government and industry on problems in various real-time and embedded systems designs. Dr. Kuo received several research awards in Taiwan, including the Distinguished Research Award from the ROC National Science Council in 2003 and the Young Scholar Research Award from Academia Sinica, Taiwan, ROC, in 2001. Ching-Chi Hsu was born in Taipei, Taiwan in 1949. He received his BS degree in physics from National Tsing Hwa. University in 1971, Hsishu, Taiwan, and both his MS. and Ph.D. degrees in computer engineering from EE department of National Taiwan University, Taipei, Taiwan, in 1975 and 1982, respectively. In 1977, he joined the faculty of the Department of Computer Science and Information Engineering at National Taiwan University and became an associate professor in 1982. During the years between 1987 and 2002, he was first engaged as a professor and became the chairman of the department. During his tenure in National Taiwan University, Dr. Hsu was a visiting scholar of Computer Science Department, Stanford University from 1984 to 1985. After serving in National Taiwan University for over 25 years, Dr. Hsu had left and was promoted as the president of Kai Nan University in 2002. Starting from February 2004, Dr. Hsu has been the executive vice president of the Institute for Information Industry in which he is mainly in charge of accelerating the growth of information industry in the whole nation. His research interests include distributed processing of data and knowledge, mobile computing and wireless networks.     

基于TD-SCDMA的AMC技术研究

自适应调制编码(AMC)是高速下行分组接入(HSDPA)的关键技术之一,它可以根据信道质量情况的改变调整调制与编码方式,从而合理地利用和分配系统资源.文中概述了AMC技术原理、特点、结构和流程,对基于TD-SCDMA的AMC 技术性能进行仿真和分析.通过仿真结果,分析了在不同情况下该编码的主要技术特点,并做出了相关的结论.     

阵列天线波束成形技术在宽带CDMA下行链路中的应用

本文利用自适应天线阵列上行链路信号到达角估计信息,并结合导频辅助下行链路信道矩阵估计值,在前人提出的具有反馈特性的自适应发送阵列原理基础上,提出一种简单可行的宽带CDMA下行链路天线阵列波束成形权重计算方法,并进一步分析了到达角估计误差和信道信息反馈时延对权重计算的影响,最后给出系统误码率性能的计算机仿真结果。     

TDD OFDM系统中下行链路多址接入方式性能分析

对应用于OFDM系统下行链路的几种多址方式,TDMA、FDMA和CDMA进行了比较分析.研究表明,在系统用户数和速率相同时,采用CDMA多址方式的OFDM系统误比特率性能优于TDMA和FDMA.在时分双功(TDD)方式下,发射机已知信道增益时,最优子载波分配的FDMA OFDM系统性能优于其他多址技术.     

A Simplified Downlink Transmission and Receiving Scheme for IDMA

In this paper, we propose a downlink transmission and receiving scheme for interleave-division multiple access （IDMA） system based on time-division duplexing （TDD） mode and time-reversal （TR） technique. The proposed scheme uses the time-reversed version of the channel impulse responses （CIR） obtained from the transmitted signal at base uplink to pre-process the station. By exploiting the weak correlations of fading channels for different user ends （UE）, it is helpful to alleviate the multi-user interference （MUI） and co-channel interference （CCI）. Moreover, the application of the TR technique in a multiple input-single output （MISO） configuration can reduce the delay spread of the channel impulse response, and mitigate inter-symbol interference （ISI）. The UE can be simplified by canceling the iteration operation. Thus the data detection of the proposed scheme is rather simple as compared with the traditional IDMA, the complexity and computational load of UE is decreased substantially, and the proposed scheme provides a great deal of privacy and security to mobile users.