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performance Analysis of the Dynamic CSMA/CD protocol in a Wireless Channel

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Journal of Systems Engineering and Electronics 2003年第3期14卷 28-32页

作者： Sha Xuejun & zhang naitong communication research center, harbin institute of technology, harbin 150001, p.r. china communication research center Harbin Institute of Technology Harbin 150001 P. R. China

In wireless networks, packet access is a popular mode, and the key problem is how to improve throughput and access delay performance, especially the throughput for wireless channels. These results will be a reference ... 详细信息

关键词： MAC protocol CSMA/CD Dynamic parameter Wireless channel.

Study on Cell Error rate of a Satellite ATM System Based on CDMA

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Journal of Systems Engineering and Electronics 2003年第1期14卷 1-5页

作者： Zhao Tongyu & zhang naitong communication research center, harbin institute of technology, harbin 150001, p. r. china communication research center Harbin Institute of Technology Harbin 150001 P. R. China

In this paper, the cell error rate (CEr) of a CDMA-based satellite ATM system is analyzed. Two fading models, i.e. the partial fading model and the total fading model are presented according to multi-path propagation fading and shadow effect. Based on the total shadow model, the relation of CEr vs. the number of subscribers at various elevations under 2D-rAKE receiving and non-diversity receiving is got. The impact on cell error rate with pseudo noise (pN) code length is also considered. The result that the maximum likelihood combination of multi-path signal would not improve the system performance when multiple access interference (MAI) is small, on the contrary the performance may be even worse is abtained.

关键词： Satellite ATM CDMA rAKE receiver.

A New Signal processing Technique of π/4-DQpSK Modem Based on Software radio

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Journal of Systems Engineering and Electronics 2003年第2期14卷 20-24页

作者： Chang Jiang & zhang naitong communication research center, harbin institute of technology, harbin 150001, p. r. china communication research center Harbin Institute of Technology Harbin 150001 P. R. China

DQpSK modem has been chosen as the modem scheme in many mobile communication systems. A new signal processing technique of π/4-DQpSK modem based on software radio is discussed in this paper. Unlike many other software radio solutions to the subject, we choose a universal digital radio baseband processor operating as the co-processor of DSp. Only the core algorithms for signal processing are implemented with DSp. Thus the computation burden on DSp is reduced significantly. Compared with the traditional ones, the technique mentioned in this paper is more promising and attractive. It is extremely compact and power-efficient, which is often required by a mobile communication system. The implementation of baseband signal processing for π/4-DQpSK modem on this platform is illustrated in detail. Special emphases are laid on the architecture of the system and the algorithms used in the baseband signal processing. Finally, some experimental results are presented and the performances of the signal processing and compensation algorithms are evaluated through computer simulations.

关键词： DQpSK Baseband signal processing DSp Software radio.

Characterizing Ultra-wide Band indoor line-of-sight wireless channel

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Journal of Systems Engineering and Electronics 2007年第4期18卷 673-678,697页

作者： Wang Yang zhang naitong zhang Qinyu zhang Zhongzhao communication research center Harbin Institute of Technology Harbin 150001 P. R. China

By exploring the deterministic characteristics of the measurement data, a new propagation model with two deterministic clusters and stochastic arriving rays within each cluster is proposed. When considering the cumulative distribution function （CDF） of the three key channel statistics, the proposed model fits the measurement data better than SV/IEEE 802.15.3, a model which is known as a standard model for UWB indoor propagation channel. Therefore, with the additional knowledge of the specific environment geometry, the proposed model generating impulse responses ＂resemble＂ the measured channel impulse responses better than IEEE model. Moreover, the proposed model＇s parameters obtaining procedure is simplified by utilizing simple parameters of the environment.

关键词： UWB wireless channel propagation characteristic indoor channel.

A Novel resource Allocation Algorithm based on Downlink and Uplink Decouple Access Scheme in Heterogeneous Networks

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china communications 2016年第6期13卷 22-31页

作者： Laiwei Jiang Xuejun Sha Xuanli Wu naitong zhang communication research center Harbin Institute of Technology

Traditional cellular network requires that a user equipment(UE) should associate to the same base station(BS) in both the downlink(DL) and the uplink(UL). Based on dual connectivity(DC) introduced in LTE-Advanced r12, DL/UL decouple access scheme has been proposed, which is especially suitable for heterogeneous networks(Het Nets). This paper is the pioneer to take the DL/UL decouple access scheme into consideration and develop a novel resource allocation algorithm in a two-tier Het Net to improve the total system throughput in the UL and ease the load imbalance between macro base stations(MBSs) and pico base stations(pBSs). A model is formulated as a nonlinear integer programming, and the proposed algorithm is a sub-optimal algorithm based on the graph theory. First, an undirected and weighted interference graph is obtained. Next, the users are grouped to let users with large mutual interferences to be assigned to different clusters. Then, the users in different clusters are allocated to different resource blocks(rBs) by using the Hungarian algorithm. Simulation results show that the proposed algorithm can provide great promotions for both the total system throughput and the average cell edge user throughput and successfully ease the load imbalance between MBSs and pBSs.

关键词： LTE-Advanced downlink and up-link decouple access scheme heterogeneous networks resource allocation graph theory