CHUPT (Vol.10, No.1, Jun.2003)

PAPERS

03101

The Applicative Investigation of Adaptive BP Networks for Multi-user Detection in Asynchronous DS-CDMA Mobile Communications

NI Liang-fang, ZHANG Bao-yu, WU Xin-yu

Abstract: Three-layer Adaptive Back-Propagation Neural Networks(TABPNN) are employed for the demodulation of spread spectrum signals in a multiple-access environment. A configuration employing three-layer adaptive Back-propagation neural networks is put forward for the demodulation of spread-spectrum signals in asynchronous Gaussian channels. The theoretical arguments and practical performance based on the neural networks are analyzed. The results show that whether the resistance to the multiple access interference or the robust to near-far effects, the proposed detector significantly outperforms not only the conventional detector but also the BP Neural networks detector and is comparable to the optimum detector.

03102

Property of the Constant Modulus Algorithm to Capture the Weak Signal

LI Ning, GUO Yan, GUO Li

03103

The Multi-level Recovery of Main-memory Real-time Database Systems with ECBH

ZOU Yong-gui, GE Jun-wei

Abstract: Storing the whole database in the main-memory is a common method to process real-time transaction in real-time database systems. The recovery Machanism of Main-memory Real-time Database Systems(MMRTDBS) should reflect the characterististics of the main-memory database and real-time database because their structures are quite different from other conventional database stystems. In this paper, therefore, we propose a multi-level recovery mschanism for main-memory real-time database systems with Extendible Chained Bucket Hashing(ECBH). Owing to the occurrence of real time data in real-time systems,we should also consider it in ourr recovery mechanism. According to our performance test, this mechanism can improve the transaction concurrency, reducing transactions' dealine missing rate.

03104

An Applied Method for Designing Maximally Decimating Non-uniform Filter Banks

LI Xue-bin,LIU Ze-min

Abstract: Assembling individual line phase filters to form a multi-channel filter bank allows the synthesis filter to be similar to corresponding analysis filters, and the design calculation can be simple. The appropriate relations between synthesis filters and analysis filters eliminate most aliasing resulting from decimation in non-uniform maximally decimating filter banks, and LS algorithm and Remez algorithm are used to optimize the composite character. This design method can achieve approximate Perfect-Reconstruction. An example is given in which the general parameter filters with approximate line phase are used as units of a filter bank.

03105

Recognition of continuous Digits by Quantum Neural Networks

LI Fei, ZHAO Sheng-mei, ZHENG Bao-yu

Abstract: This paper describes a new kind of neural network - Quantum Neural Network (QNN) and its application to recognition of continuous digits. QNN combines the advantages of neural modeling and fuzzy theoretic principles. Experiment results show that more than 15% error reduction is achieved on a speaker-independent continuous digits recognition task compared with BP network.

03106

On Timing Offset Estimation for OFDM

XIAO Jian-hua, ZHANG Ping

Abstract: In this paper, a new timing offset estimation method for Orthogonal Frequency Division Multiplexing (OFDM) systems are presented. Upon the receipt of just one training sequence, this presence of a signal and the start of the frame can be detected. The performances of the timing estimator in additive white Gaussian noise and the mobile multipath channel are evaluated by simulation. The results delivered by this algorithm are compared with those delivered by Schmidl and Cox.

03107

Blocking Probability Based Hierarchical Storage Design in VOD System

LI Qing-guo, SUN Song-lin, CAI An-ni, SUN Jing-ao

Abstract: In this paper, we discuss the relationship between the blocking probability and the configuration of storage hierarchy in a VOD server using the queueing model we propose. With this model , the optimal configuration of the storage system can be obtained.

03108

A Conflict Detection Scheme for Concurrency Control of R-tree

XIA Ying, PENG Da-qin

Abstract: Despite extensive research on R-trees, most of the proposed schemes have not been integrated into existing DBMS owing to the lack of protocol of concurrency control. R-link tree is an acceptable data structure to deal with this issue, but problems like phantom still exist. In this paper, we focus on a conflict detection scheme based on R-link tree for complete concurrency control. An in-memory operation control list is designed to suspend conflicting operations. The main features of this approach are (1) it can be implemented easily and does not need any extra information. (2) No deadlocks are involved in locking scheme. (3) Non-conflicting operations are not restricted. (4) Phantom problem in R-link tree are avoided through beforehand predication. The experiment results show that this scheme is correct and gains better system performance.

03109

A Design of the Quantizer of H.261 CODEC

HUNAG Ting-xue , ZHU Zhi-xiang ,DAI Guan-zhong

Abstract: This paper introduces two steps to design a quantizer of H.261 CODEC: the first step is to implement the coarse quantizing through control algorithm for buffer's occupation ratio; The second step is to finish the accurate quantizing through the control algorithm of visual characteristics. Moreover satisfactory effect are got using these algorithms through experiment.

CORRESPONDENCE

03110

BaMAP: A Broadband Multimedia Application Platform

SUN Song-lin, LI Qing-guo, CAI An-ni, SUN Jing-ao

Abatract: In this paper, a broadband multimedia application platform, BaMAP, is introduced. The BaMAP aims to offer content and service providers a good integrated environment for efficient content production, management, delivery and sharing. It supports large-scale hierarchical storage, as well as mechanisms for content distribution and queries from remote nodes. The on-demand service, part of the BaMAP, offers two access interfaces, DVB-C and IP, which allow the platform to run on most of the existing access networks.

03111

Resources Management in Active Network

WANG Jin-guo, LI Zeng-zhi, KOU Yan-an

Abstract: In an active network, users can insert customized active codes into active nodes to execute. Thus it needs more resources than those required by conventional networks, and these resources must be effectively monitored and managed. Management policies in existing OSs are too complicated to apply to simple active packets. In this paper, we present new resources management policies that mainly adopted to manage CPU, storage and transmission bandwidth. Namely, we use SPF algorithm to schedule and process active packets, and import an interval queue method to allocate transmission bandwidth, and use feedback mechanism to control congestion. At the same time, we design some experiments on prototype system with and without resources management policies respectively. The experiments results show that management policies presented by us can effectively manage resources in active nodes and can improve the performance of active network.

03112

On Universal Telecommunication Service and West China Development

LIU Yue, QU Xue-lian, HUANG Cui-ping

Abstract: This paper aims at studying the relationship between universal telecommunication service and West China development. It, firstly, introduces our country's demands for universal telecommunication service; secondly, analyses the demand of West China development for the universal telecommunication service, thirdly, depicts the development status of telecommunication industry of west region; fourthly, points out the meaning of universal telecommunication service to west area, and lastly brings forward the connotation of universal telecommunication service of west area.