共查询到17条相似文献，搜索用时 265 毫秒
1.
空时MIMO-OFDM 系统中基于扩展Kalman 滤波的信道估计 总被引：1，自引：1，他引：1
A space-time coded multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system is considered as a solution to the future wideband wireless communication system.This paper proposes an extended Kalman filtering-based (EKF-based) channel estimation method for space-time coded MIMO-OFDM systems.The proposed method can exploit pilot symbols and an extended Kalman filter to estimate channel without any prior knowledge of channel statistics.In comparison with the least square (LS) and the least mean square (LMS) methods,the EKF-based approach has a better performance in theory.Computer simulations demonstrate the proposed method outperforms the LS and LMS methods.Therefore it can offer dramatic system performance improvement at a modest cost of computational complexity. 相似文献
2.
Space-time signal processing based on multiple-input multiple-output（MIMO） systems is an active research field in which interfering signals are cancelled and multiuser detection is achieved using space diversity. In a Rayleigh fading channel, space-time block cedes using multiple transmitting antennas can improve system performance and reduce bit-error-rate for multiuser detection. In this paper, several antenna configurations are designed for DS-CDMA communication in MIMO systems. Space-time linear multinser detection and space-time serial interference cancellation multiuser detection are simulated. Bit-error-rate and computation complexities of the two methods are compared. Conclusions are given in the end. 相似文献
3.
The downlink frame structure for beyond 3G mobile communication systems is presented. Beyond 3G systems utilize the OFDM technique. However, a problem encountered in OFDM is that channel dispersion destroys orthogonality between carriers, caushag inter-symbol interference. It is also sensitive to high peak to mean power ratio （PAPR）. Therefore it spends much time on obtaining frequency, time, and frame synchronization. This paper proposes to add a frame synchronization channel in the time domain to overcome the shortcoming of OFDM. As transmitter diversity improves the system performance, beyond 3G systems employ space-time block coded （STBC）. Fast cell search algorithm including slot synchronization, frame synchronization and cell ID identification is then discussed, which is based on the frame synchronization channel in transmitter diversity systems. Detection and false alarm probabilities in AWGN and Rayleigh channels are analyzed, and the mean acquisition time is obtained. Computer simulations are conducted to evaluate the performance of the cell search algorithm under different channel conditions. 相似文献
4.
We presented a wireless endoscope system developed on the embedded Linux platform. This wireless endoscope system consists of three parts： the endoscope capsule, the portable equipment and the image workstation, which make this system wireless and portable. Hardware design of this system and software design of the portable equipment are described. In clinical use, patients swallow the endoscope capsule for gastrointestinal inspection. The portable equipment receives images of gastrointestinal tract via the radio frequency module while it sets and reads back parameters of the capsule via the low frequency module. Acquired image data can be saved as a FAT32 format file in an universal serial bus disk. Images can be processed and reviewed at an Microsoft Windows PC workstation in the next stage. The image acquired by this wireless endoscope system is quite effective with clear details of gastrointestinal tract. However, the endoscope capsule was large, making it difficult to swallow. So the printed circuit board design of endoscope capsule needs to be improved. 相似文献
5.
WANG Cheng-gang MO Zhi-hong 《重庆大学学报(英文版)》2007,6(3):151-154
A GoBlast system was built to predict gene function by integrating Blast search and Gene Ontology (GO) annotations together. The operation system was based on Debian Linux 3.1, with Apache as the web server and Mysql database as the data storage system. FASTA files with GO annotations were taken as the sequence source for blast alignment, which were formatted by wu-formatdb program. The GoBlast system includes three Bioperl modules in Perl:a data input module, a data process module and a data output module. A GoBlast query starts with an amino acid or nucleotide sequence. It ends with an output in an html page, presenting high scoring gene products which are of a high homology to the queried sequence and listing associated GO terms beside respective gene poducts. A simple click on a GO term leads to the detailed explanation of the specific gene function. This avails gene function prediction by Blast. GoBlast can be a very useful tool for functional genome research and is available for free at http://bioq.org/goblast. 相似文献
6.
The spatial distribution of extracellular polymeric substances （EPS） in a pilot-scale membrane bioreactor （MBR） was studied. The sampling points on top of and inside the membrane module were measured and analyzed by the experimental variant function. The content of EPS was spatially interpolated by ordinary Kriging method, and il- lustrated with SURFER software. A case study was carried out in an MBR with membrane aperture of 0.4 ~tm and handling capacity of 120 ma/d in Jizhuangzi sewage treatment plant, Tianjin. From the visualization of EPS distribu- tion, it is seen that on the horizontal plane, the content of EPS was the lowest at the center; and on the vertical plane, the content of EPS decreased with the increase of depth. The shearing force caused by aeration of perforated pipe and the influent mode are the main influencing factors for this distribution. 相似文献
7.
ZOU Lian-ying ZOU Xue-cheng 《浙江大学学报(A卷英文版)》2006,7(4):591-596
INTRODUCTION With the development of Ethernet systems and the growing capacity of modern silicon technology, embedded communication networks are playing an increasingly important role in embedded and safety critical systems. Advances in VLSI technology have also pushed integration to the point where it is now possible to design and implement a microprocessor and network controller on a single chip, known as System-on-Chip (SoC). In a network of embedded systems, each system can communi… 相似文献
8.
The paper investigates closed-loop transmit diversity （CLTD） systems with antenna selection technique. The expected received signal-noise-ratio （RxSNR） of the proposed systems is analyzed and compared with CLTD systems. An algorithm is proposed for determining the number of increased transmit antennas in terms of a reduced RF chains without performance degradation. Since a feedback channel is bandwidth-limited, we present a method of quantizing transmit-weight vectors. Simulation results demonstrate advantage of the proposed systems with full and quantized feedback information. Quantized feedback has less effect on the proposed systems than CLTD systems. 相似文献
9.
Abstract： An innovative occupant friendly retrofitting technique has been developed for reinforced concrete （RC） building structures with hollow brick infill wails used as partition walls which constitute the major portion of the existing building stock in Turkey. The idea is to convert the existing hollow brick infill wall into a load carrying system acting as a cast-in-place RC wall by reinforcing it with relatively thin concrete plates bonded to the mortar coated infill wall by use of tile adhesive and fixed by qb6 （6 mm diameter） bolts. Test parameters were the shape and thickness of the plates, presence of reinforcement in plates, number and arrangement of O6 bolts. It was observed that lateral strength, stiffness, energy dissipation capacity, and ductility of the strengthened infill walls were improved and behaviour was enhanced by the proposed technique. Plates with two different basic shapes were used to strengthen the test specimens. 相似文献
10.
The problem of monitoring an electric power system by placing as few measurement devices in the system as possible is closely related to the well-known vertex covering and dominating set problems in graph theory. In this paper, it was shown that the power domination number of an outerplanar graph with the diameter two or a 2-connected outerplanar graph with the diameter three is precisely one. Upper bounds on the power domination number for a general planar graph with the diameter two or three were determined as an immediate consequences of results proven by Dorfling, et al. Also, an infinite family of outerplanar graphs with the diameter four having arbitrarily large power domination numbers were given. 相似文献
11.
INTRODUCTION High data rate and high quality multimedia ser- vices are required in beyond third generation (B3G) and fourth generation (4G) mobile communications. Space-time coding scheme has been proposed (Tarokh et al., 1998; 1999) to achieve higher capacity and data rate. So far, most research on space-time coding assumed that accurate channel estimations are available at the receivers. However, accurate channel estimation is difficult and too many training symbols are required in a r… 相似文献
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13.
INTRODUCTION Unitary space-time modulation (USTM) (Hochwald and Marzetta, 2000) has been shown to be ideally suited for Rayleigh flat fading channels when there is no CSI. And for continuously changing fading channels, differential unitary space-time modulation (DUSTM) was proposed in Hochwald and Sweldens (2000). However, the performance of DUSTM de-grades considerably in frequency-selective fading channels often encountered in broadband wireless communications. Hence concatena… 相似文献
14.
Recent research challenges in the wireless communication include the usage of diversity and efficient coding to improve data transmission quality and spectral efficiency. Space diversity uses multiple transmitting and/or receiving antennas to create independent fading channels without penalty in bandwidth efficiency. Space-time block coding is an encoding scheme for communication over Rayleigh fading channels using multiple transmitting antennas. Space-time block codes from complex orthogonal designs exist only for two transmitting antennas. This paper generalizes a new complex orthogonal space-time block code for four transmitting antennas, whose decoding complexity is very low. Simulations show that the generalized complex orthogonal space-time block code has low bit error rate, full rate and possibly large diversity. 相似文献
15.
随着计算机技术、视频编码技术、音频编码技术、流媒体技术和网络通信技术的不断发展,超媒体技术的综合应用优势逐渐在远程教学中显现出来.本文应用超媒体技术构建了与现代教育相适应的教学、管理和服务的远程教学系统,该系统具有超媒体系统所特有的实时交互性、高度集成性、超越时空性、生动趣味性和知识容量大等特点,它的推广使用将为优质教育资源的合理配置提供一个更为有效的应用平台. 相似文献
16.
郭占祥 《张家口职业技术学院学报》2011,24(1):53-56
针对目前多种图书查询系统使用传统人工的方式管理图书效率低的缺点,运用现代管理技术,采用FoxPro6.0数据库开发软件,通过新建"表"、"表单"、"菜单"和"报表"以及书写相应的程序代码连接"表单"和"菜单"的方式主要设计了"系统登录模块"、"查询模块"和"报表模块",并以"《三国演义》"一书的查询为实例验证了该书籍查询系统的可行性,为建立科学的书籍查询系统、提高图书管理工作效率提供参考。 相似文献
17.
RLS channel estimation with adaptive forgetting factor in space-time coded MIMO-OFDM systems 总被引：1，自引：0，他引：1
LIANG Yong-ming LUO Han-wen HUANG Jian-guo 《浙江大学学报(A卷英文版)》2006,7(4):507-515
INTRODUCTION The very dramatic increase in demand for high-rate data transmission stimulated greater re- search efforts in developing wideband wireless communication systems which could support high- rate transmission over wireless channels. But we have to face the challenges from the multi-path effects because multi-path propagation of wire wave is usu- ally seen as a harmful factor which leads to one of the most troublesome radio channel problems. However, the multi-path effects can beco… 相似文献