检索结果-南通市图书馆

The Analysis of Secure HARQ with Chase Combining over Block Fading Channel

在线全文

学校读者我要写书评

暂无评论

China communications 2016年第5期13卷 82-88页

作者： Yue Wu Lukman A Olawoyin Nana Zhang Hongwen Yang wireless communication center School of Information and Communication EngineeringBeijing University of Posts and Telecommunications

In this letter, the physical layer security of hybrid automatic repeat request with chase combining(HARQ-CC) scheme is investigated from the viewpoint of information theory. Different from the literature which used Wyner code, our analysis focuses on the general scenario without specific code. We firstly obtain the outage probability of both main channel and wiretap channel. Since retransmissions are completely determined by main channel, we then prove that its achievable diversity order equals to maximum transmission number() while this order of wiretap channel is only one. Furthermore, we evaluate the metric of secure gap which demonstrates the difference between main channel and wiretap channel with reliable and secure constraints. As increases, the secure gap decreases monotonously. When is large enough, the security can be guaranteed even if wiretap channel is better than main channel.

关键词： physical layer security HARQ chase combining outage probability diversity order secure gap

Performance Analysis in Cloud Radio Access Networks:User-Centralized Coordination Approach

在线全文

学校读者我要写书评

暂无评论

China communications 2015年第11期12卷 12-23页

作者： Munzali Ahmed Abana SUN Yaohua Manzoor Ahmed Lukman A.Olawoyin LI Yong Key Laboratory of Universal wireless communication Ministry of EducationBeijing University of Posts and Telecommunications wireless communication center Beijing University of Posts and Telecommunications

The cloud radio access network(C-RAN) has recently been proposed as an important component of the next generation wireless networks providing opportunities for improving both spectral and energy effi ciencies. The performance of this network structure is however constrained by severe inter-cell interference due to the limited capacity of fronthaul between the radio remote heads(RRH) and the base band unit(BBU) pool. To achieve performance improvement taking full advantage of centralized processing capabilities of C-RANs,a set of RRHs can jointly transmit data to the same UE for improved spectral effi ciency. In this paper,a user centralized joint coordinated transmission(UC-JCT) scheme is put forth to investigate the downlink performance of C-RANs. The most important benefit the proposed strategy is the ability to translate what would have been the most dominant interfering sources to usable signal leading to a signifi cantly improved performance. Stochastic geometry is utilized to model the randomness of RRH location and provides a reliable performance analysis. We derive an analytical expression for the closed integral form of the coverage probability of a typical UE. Simulation results confirm the accuracy of our analysis and demonstrate that significant performance gain can be achieved from the proposed coordination schemes.

关键词： cloud radio access network poisson point process coverage probability joint coordinated transmission baseband unit

Fuzzy-Based Dynamic Distributed Queue Scheduling for Packet Switched Networks

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2013年第2期28卷 357-365页

作者： Chollette C.Chude-Olisah Uche A.K.Chude-Okonkwo Kamalrulnizam A.Bakar Ghazali Sulong Faculty of Computing Universiti Teknologi Malaysia wireless communication center Universiti Teknologi Malaysia

Addressing the problem of queue scheduling for the packet-switched system is a vital aspect of congestion control. In this paper, the fuzzy logic based decision method is adopted for queue scheduling in order to enforce some level of control for traffic of different quality of service requirements using predetermined values. The fuzzy scheduler proposed in this paper takes into account the dynamic nature of the Internet traffic with respect to its time-varying packet arrival process that affects the network states and performance. Three queues are defined, viz low, medium and high priority queues. The choice of prioritizing packets influences how queues are served. The fuzzy scheduler not only utilizes queue priority in the queue scheduling scheme, but also considers packet drop susceptibility and queue limit. Through simulation it is shown that the fuzzy scheduler is more appropriate for the dynamic nature of Internet traffic in a packet-switched system as compared with some existing queue scheduling methods. Results show that the scheduling strategy of the proposed fuzzy scheduler reduces packet drop, provides good link utilization and minimizes queue delay as compared with the priority queuing （PQ）, first-in-first-out （FIFO）, and weighted fair queuing （WFQ）.

关键词： fuzzy logic based decision method priority queue limit queue scheduling

A Resource Scheduling Scheme for Spectrum Aggregation in Cognitive Radio Based Heterogeneous Networks

在线全文

学校读者我要写书评

暂无评论

China communications 2015年第9期12卷 100-111页

作者： Fu Yunhai Ma Lin Xu Yubin Harbin Institute of Technology communication Research center Key Laboratory of Police wireless Digital communication Ministry of Public Security

In spectrum aggregation(SA), two or more component carriers(CCs) of different bandwidths in different bands can be aggregated to support wider transmission bandwidth. The current resource scheduling schemes for spectrum aggregation are not optimal or suitable for CR based heterogeneous networks(Het Nets). Consequently, the authors propose a novel resource scheduling scheme for spectrum aggregation in CR based Het Nets, termed as cognitive radio based resource scheduling(CR-RS) scheme. CR-RS has a three-level structure. Under a dynamic traffic model, an equivalent throughput of the CCs based on the knowledge of primary users(PUs) is given. On this basis, the CR users data transmission time of each CC is equal in CR-RS. The simulation results show that CR-RS has the better performance than the current resource scheduling schemes in the CR based Het Nets. Meanwhile, CR-RS is also effective in other spectrum aggregation systems which are not CR based HetNets.

关键词： CR-RS spectrum aggregation resource scheduling cognitive radio heterogeneous networks

Pilot power based rate control in CDMA 2000 1x EV-DO Rev-A

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 118-122页

作者： LIU Xiao-feng GU Jian YANG Hong-wen wireless communication center Beijing University of Posts andTelecommunications Beijing 100876 China

This article proposes a new algorithm to improve the rate control efficiency of enhanced reverse link medium access control （RLMAC） in the code division multiple access （CDMA） 1x EV-DO release A（Rev. A） system. The new algorithm brings reverse access terminal （AT） pilot power to the RLMAC rate control procedure and makes it easier for a low pilot power user to increase its data rate when the system is slightly loaded and harder to decrease its date rate when the system is heavily loaded. Numerical results of system level simulations show that the new algorithm can bring higher system throughput, lower AT transmission power, and lower system load.

关键词： RLMAC CDMA 1x EV-DO pilot power rate control

Graph partitioning algorithm for opportunistic routing in large-scale wireless network

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2009年第4期16卷 42-46页

作者： LI Yan-hua LIU Yuan-an wireless communication center Beijing University of Posts and Telecommunications Beijing 100876 China

Opportunistic routing takes advantage of the broadcast nature of wireless communications by forwarding data through a set of opportunistic paths instead of one ＇best＇ path in traditional routing. However, using the global scheduling opportunistic scheme like the existing opportunistic routing protocol （ExOR） would consume considerable transmission latency and energy in large-scale wireless topologies. In this article, a graph partitioning algorithm is proposed, namely, minimum cut with laplacians （MCL）, to divide the Ad-hoc network topology into subgraphs with minimized edge cuts across them. Then the existing opportunistic routing can be applied locally in each subgraph. In this way, forwarders in different subgraphs can transmit simultaneously, and each node only needs to maintain a local forwarder list instead of a global one. The simulations show that using MCL scheme in the opportunistic routing can reduce the end-to-end delay by about 49%, and increase the life time of the wireless node by about 39%.

关键词： opportunistic routing graph partitioning wireless routing mobile Ad-hoc network

A resilient trust management scheme for defending against reputation time-varying attacks based on BETA distribution

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2017年第4期60卷 60-70页

作者： Weidong FANG Wuxiong ZHANG Yang YANG Yang LIU Wei CHEN Key Laboratory of wireless Sensor Network & communication Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai Research center for wireless communication School of Computer Science and Technology China University of Mining and Technology

Compared with the encryption and the authentication which can prevent the external attacks,the trust management schemes are the better approaches for defending against the internal attacks in wireless sensor network(WSN). The reputation time-varying(RTV) attacks are internal attacks. In the reputation timevarying attacks, the reputation value of nodes is manipulated to adjust dynamically by the compromised nodes or malicious attackers. Hence, these attacks have greater covert and invasive. In this paper, we propose a Timewindow-based Resilient Trust Management Scheme(TRTMS) to defend against the reputation time-varying attacks in wireless sensor network. In this scheme, based on BETA distribution, the behaviors of compromised nodes are analyzed for a period of time, and then the difference judgment and the trend analysis are utilized to identify the abnormality of nodes’ reputation value, meanwhile, the control factor Fc and the time window are introduced to verify and remove the compromised modes from the suspected malicious nodes, which refer to those nodes’ reputation value changes are caused by the wireless channel changes. The result of simulation shows that our proposed scheme can defend reputation time-varying attacks effectively and it is convenient to implement.

关键词： wireless sensor network(WSN) reputation time-varying attack trust value trust management time window

A Semi-Supervised WLAN Indoor Localization Method Based on l1-Graph Algorithm

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2015年第4期22卷 55-61页

作者： Liye Zhang Lin Ma Yubin Xu communication Research center Harbin Institute of Technology Key Laboratory of Police wireless Digital communication Ministry of Public Security

For indoor location estimation based on received signal strength( RSS) in wireless local area networks( WLAN),in order to reduce the influence of noise on the positioning accuracy,a large number of RSS should be collected in offline phase. Therefore,collecting training data with positioning information is time consuming which becomes the bottleneck of WLAN indoor localization. In this paper,the traditional semisupervised learning method based on k-NN and ε-NN graph for reducing collection workload of offline phase are analyzed,and the result shows that the k-NN or ε-NN graph are sensitive to data noise,which limit the performance of semi-supervised learning WLAN indoor localization system. Aiming at the above problem,it proposes a l1-graph-algorithm-based semi-supervised learning( LG-SSL) indoor localization method in which the graph is built by l1-norm algorithm. In our system,it firstly labels the unlabeled data using LG-SSL and labeled data to build the Radio Map in offline training phase,and then uses LG-SSL to estimate user's location in online phase. Extensive experimental results show that,benefit from the robustness to noise and sparsity ofl1-graph,LG-SSL exhibits superior performance by effectively reducing the collection workload in offline phase and improving localization accuracy in online phase.

关键词： indoor location estimation l1-graph algorithm semi-supervised learning wireless local area networks(WLAN)

A random linear code based secure transmission scheme for wireless fading channels

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2017年第4期60卷 241-243页

作者： Lukman A.OLAWOYIN Nana ZHANG A.O.OLOYEDE Nasir FARUK Hongwen YANG wireless communication center Beijing University of Posts and Telecommunications Department of Telecommunication Science University of Ilorin

Dear editor,wireless transmissions are vulnerable to potential security threats such as eavesdropping and wiretapping since unauthorized reception is facilitated through wireless channels[1].Traditional system security is mainly implemented in the higher layers of the communication protocol stack,relying on authentication and cryptography[2].The recent researches explore security in the physical layer[3],which can help to protect the information

关键词： code length A random linear code based secure transmission scheme for wireless fading channels