一种基于IEEE802.15.3协议物理层编码调制方案

本文分析了IEEE802．15．3协议的物理层采用的信道编码调制技术，给出了一种基于Turbo码编码思想的编码调制方案TTCM-MQAM。并与协议中采用的TCM-MOAM编码调制进行了性能比较。通过分析与仿真得出，TTCM-MOAM相比于TCM-MQAM在性能上有很大的提高．对于IEEE802．15．3微网的传输有很重要的意义。     

EPS外墙外保温施工中遇到的几点问题

由于国家标准、行业标准、地方标准的规定存在矛盾以及施工图设计深度不够,在外墙外保温施工中经常遇到一些问题,主要表现为:是否采用锚栓辅助固定,保护层方面的问题、分隔缝设置问题.通过分析和调查得出解决方案并实施,取得了较好的效果.     

Improvement of Data Rate Performance of Wireless Local Area Networks through the Use of Orthogonal Code Division Multiplexing (OCDM), Multipath Diversity,and Parallel Concatenated Channel Encoding

The widespread use of Wireless Local Area Networks (WLAN) and the desire for such products from different vendors to operate together has generated a movement towards standardization. Over the last few years, several organizations worldwide have researched and developed WLAN standards like IEEE 802.11/15, HIPERLAN, multimedia mobile access communication (MMAC), etc., to name a few. One of the important considerations in designing and marketing WLAN products is the data rate supported by them. This paper deals with the development of a modification of the Direct Sequence (DS) physical layer standard in IEEE 802.11b to allow reliable higher data rates beyond the 1–2 Mb/s supported by the standard. More precisely, this paper proposes the usage of Orthogonal Code Division Multiplexing (OCDM), a form of Code Division Multiple Access (CDMA), diversity via a rake receiver, and parallel concatenated channel encoding, in order to improve the data rate performance in a multipath Rayleigh fading environment. The proposed transceiver design is described in detail and its performance is assessed via digital computer simulation of the corresponding mathematical model.     

等重码的一些新结果

本文给出两种构造二元非线性等重码的方法，这些方法是［１］文构造二元非线性循环等重码方法的改进。通过我们的构造方法可以得到几类二元最优等重码。我们进一步说明通过ＧＦ（ｑ）上的等重码和达到Ｐｌｏｔｋｉｎ界的最优码可以构造达到Ｊｏｈｎｓｏｎ上界的二元最优等重码     

Evaluation of error rate performance for ODS code‐spread system using simulations

Code‐spread and conventional CDMA systems are discussed and compared for varying interleaver sizes. Results are evaluated in terms of BER versus E_b/N_o. It is observed that the code‐spread systems give better performance. It is also observed that performance of both the systems improves significantly with an increase in the interleaver size. Copyright © 2005 John Wiley & Sons, Ltd.     

Complexity aspects of guessing prefix codes

Given a natural language cleartext and a ciphertext obtained by Huffman coding, the problem of guessing the code is shown to be NP-complete for various variants of the encoding process.     

Design of Amplitude and Phase Modulated Signals for Differential Space-Time Block Codes

A differential space-time block code (DSTBC) provides full diversity advantage and does not require any radio channel estimation in the receiver, which makes it an attractive alternative to the well-known coherent space-time block code (STBC). However the original design of DSTBC allows only pure phase shift keying (M-PSK) modulation scheme, which are not optimal for M > 4. In this paper a simultaneous amplitude and phase modulation scheme for DSTBC with 2 transmit and several receive antennas is introduced. The performance of the proposed scheme is investigated and compared with DSTBC techniques using pure M-PSK modulation. Alexandre Vanaev received B.Eng. degree in Electrical and Electronic engineering from the St. Petersburg State Polytechnic University, Russia in 1998, and M.Sc. degree in “Information and communication systems” from Technical University Hamburg-Harburg in 2002. He is currently pursuing his Ph.D. in the Technical University Hamburg-Harburg, Department of Telecommunications. His research interests include prospective OFDM-based wireless communication systems and MIMO technology. Prof. Hermann Rohling is with the Technical University Hamburg-Harburg, Germany where he has developed an international reputation for Mobile Communication (4G) and automotive radar systems. Previously Prof. Rohling was with the AEG Research Institute, Ulm as a researcher working in the area of digital signal processing for radar and communications applications. His research interests have includedWideband Mobile Communications especially based on Multicarrier Transmission Techniques (OFDM) for future broadband systems (4G), signal theory, digital radar signal processing, detection, estimation and differential GPS for high precision navigation. Prof. Rohling is a member of Informationstechnische Gesellschaft (ITG), German Institute of Navigation (DGON) and a Fellow of IEEE. He is a chairman of the September 2006 International OFDM Workshop (InOWo 2006) and the International Radar Symposium (IRS 2006) in Krakow, Poland. Prof. Rohling is theVice President of the Technical University Hamburg-Harburg.     

Probability-based design standards of structures

The process of developing probability-based codes in the past three or four decades has been applied in rules in the deterministic form of partial reliability factors. The situation in North America and western Europe is very well known. Our paper partially reviews developments in middle and eastern Europe and presents some examples of results. In accordance with the paper (Ellingwood, B. R., Probability-based codified design: past accomplishment and future challenges. Structural Safety, 1994, 13, 159–176.) it advocates a preparation of international rules for the direct use of reliability methods in structural design.     

在VHF移动信道中不同条件下BCH码的纠错性能研究

本文在文献［７］基础上研究了采用分组ＢＣＨ码加交错技术抗衰落的性能。模拟了：ＢＣＨ（６３ ３９ ４）码、ＢＣＨ（１２７ ７８ ７）码和ＢＣＨ（１２７ ６４ １０）码在交错与非交错两种不同情况下，融载波调制方式分别为ＦＳＫ３００ｂｉｔｓ／ｓ、ＤＰＳＫ１２００ｂｉｔｓ／ｓ、ＱＰＳＫ２４００ｂｉｔｓ／ｓ和８ＰＳＫ ４８００ｂｉｔｓ／ｓ，不同车速分别为：４０ｋｍ／ｈ和１００ｋｍ／ｈ时的纠错性能。     

Low complexity concatenated coding schemes for digital satellite communications

A study of reduced complexity concatenated coding schemes, for commercial digital satellite systems with low-cost earth terminals, is reported. The study explored trade-offs between coding gain, overall rate and decoder complexity, and compared concatenated schemes with single codes. It concentrated on short block and constraint length inner codes, with soft decision decoding, concatenated with a range of Reed-Solomon outer codes. The dimension of the inner code was matched to the outer code symbol size, and appropriate interleaving between the inner and outer codes was used. Very useful coding gains were achieved with relatively high-rate, low-complexity schemes. For example, concatenating the soft decision decoded (9,8) single parity check inner code with the CCSDS recommended standard Reed-Solomon outer code gives a coding gain of 4.8dB at a bit error probability of 10^?5, with an overall rate of 0-78.