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Performance evaluation on IEEE 802.11e considering emergency calls in congested situation

中国邮电高校学报（英文版） 2007年第S1期14卷 50-54页

作者： CUI Lu-ming OKADA Kazunori KATO Toshihiko CHEN Xing-yi Information Security Center National Institute of Information and Communications Technology Tokyo 184-8795 Japan Department of Information Network System Science The University of Electro-Communications Tokyo 182-8585 Japan States Key Laboratory of Networking and Switching Beijing University of Posts and Telecommunications Beijing 100876 China

To enhance the quality of service (QoS) support in IEE 802.11, IEEE 802.11e has been studied, which introduces the so-called hybrid coordination function (HCF). HCF includes two medium access mechanisms: contention-based channel access (EDCA), and contention-free channel access (HCCA). Although IEEE 802.11e has provided differentiated channel access mechanism, when call demand rises for important festivals such as New Year's Day or large scale natural disasters such as earthquakes, the delay of voice will increase and the QoS of voice nodes will drop down rapidly. Through our simulation study, in order to guarantee the QoS of emergency voice calls in congested situation, a higher priority for these calls will be required.

关键词： IEEE 802.11e EDCA HCCA HCF emergency call wireless LAN (WLAN) congested situation QoS

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Individual communication transmitter identification using support vector machines with kernels for polyspectrum

Individual communication transmitter identification using su...

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作者： Na, Sun Zhou, Yajian Yang, Yixian Information Security Center State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China Key Laboratory of Network and Information Attack and Defense Technology MOE Beijing University of Posts and Telecommunications Beijing 100876 China National Engineering Laboratory for Disaster Backup and Recovery Beijing 100876 China

ISBN: (纸本)9780769540276

Polyspectral feature extraction is considered to be a potential method for individual communication transmitter identification. However, the curse of dimensionality caused by higher orders of the features restrains the efficiency of classification. A new method using support vector machine with kernels of polyspectra is present for classification of individual transmitters. The result of experiments on FM and AM individual transmitters shows that the number of support vectors is lower than which using conventional kernel functions, and it can achieve better classification rate. © 2010 IEEE.

关键词： Support vector machines

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Improved Global and Local Graph Neural network for Session-based Recommendation 25

Improved Global and Local Graph Neural Network for Session-b...

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25th IEEE International Conference on Computer Supported Cooperative Work in Design, CSCWD 2022

作者： Wang, Yifan Yu, Qing Wang, Zuohua Tianjin University of Technology Tianjin Key Laboratory of Intelligence Computing and Network Security Tianjin China China Everbright Bank Co. Ltd Beijing China

ISBN: (纸本)9781665405270

The session-based recommendation(SBR) aims to predict user actions based on anonymous sessions. SBR focuses on recent sessions to make more real-time and reliable recommendations and does not need to extract user IDs, thereby alleviating privacy issues. Recent research mainly models user preferences based on the target session while ignoring other sessions, which may contain items transitions related to and unrelated to the target session. This paper proposes a novel method, namely Improved Global and Local Graph Neural network (IGL-GNN), to models item transitions within not only the target session but also the other sessions. Specifically, we learn the session-level item representation from the local graph, learns the global-level item representation from the global graph. We propose a new method to effectively aggregate global and local representations, which not only retains more useful information but also removes useless information. In addition, we innovatively introduced Transformer, incorporated it into the model as a general deformation function, enhanced the ability to obtain complex transformations, and solved the limitations of the model in learning complex representations. We have done a lot of experiments on three benchmark datasets, and the results show that the performance of IGL-GNN is better than the most advanced methods. © 2022 IEEE.

关键词： Graph neural networks

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Protocol adaption of NAC in mobile telecommunication networks

Protocol adaption of NAC in mobile telecommunication network...

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2009 International Conference on Information Engineering and Computer Science, ICIECS 2009

作者： Bing, Liu Cheng, Song Yang, Xin Yixian, Yang Information Security Center State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China Key Laboratory of Network and Information Attack and Defence Technology of MOE Beijing University of Posts and Telecommunications Beijing 100876 China Beijing Safe-Code Technology Co. Ltd. China

ISBN: (纸本)9781424449941

The NAC (network Access Control) technology which enforces the endpoint access decision based on the collected endpoint security status information and platform measurement information has been developed by various companies and has been widely deployed in intranets. Besides intranet, mobile telecommunication networks also find NAC is required. This paper introduces the main NAC solutions in industry and analyzes the essential of current NAC technologies in the perspective of protocol. And then this paper describes the explicit requirement of remote platform integrity validation which may utilize the NAC in the mobile telecommunication networks and discus a feasible way of implementing the NAC technology into a scenario by using protocol adaption of EAP over IKEv2. ©2009 IEEE.

关键词： Intranets

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Three-level Compact Caching for Search Engines Based on Solid State Drives 23

Three-level Compact Caching for Search Engines Based on Soli...

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23rd IEEE International Conference on High Performance Computing and Communications, 7th IEEE International Conference on Data Science and Systems, 19th IEEE International Conference on Smart City and 7th IEEE International Conference on Dependability in Sensor, Cloud and Big Data Systems and Applications, HPCC-DSS-SmartCity-DependSys 2021

作者： Zhang, Rui Sun, Pengyu Tong, Jiancong Zang, Ruirui Qian, Heng Pan, Yu Stones, Rebecca J. Wang, Gang Liu, Xiaoguang Li, Yusen College of Computer Science Nankai University Tianjin China Tianjin Key Laboratory of Network and Data Security Technology Tianjin China Baidu Inc Beijing China

ISBN: (纸本)9781665494571

The query processing in search engines can be classified into either disk I/O operations and CPU computation operations. Conventional search engine caching methods mostly aimed at reducing disk I/O operations. However, with the new trend of using solid state drives (SSDs) instead of hard disk drives for search engine storage, the bottleneck of query processing shifts from disk I/O to computation. In this paper, we design a three-level compact caching structure suited to SSD-based search engines, incorporating caches for (a) doculets, partial documents which contain previously encountered snippets, (b) fragments, compact data structures containing snippet metadata, and (c) ranked docID lists, which index the top-k documents relevant to a query. This three-level compact caching method aims at reducing the bottleneck of repetitive CPU computation operations. Moreover, by considering different levels of caches as a whole system, the proposed three-level compact caching eliminates the redundancy among cache items. This increases the efficiency of cache space utilization. Experimental results indicate an improvement in query response latency by a factor of around 2.6 when using static caching and 1.3 under dynamic caching. © 2021 IEEE.

关键词： Costs Solid state drives Smart cities Query processing Redundancy Search engines Metadata

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Discussion and testing of 802.11ah wireless communication in intelligent substation 2

Discussion and testing of 802.11ah wireless communication in...

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2nd IEEE International Conference on Energy Internet, ICEI 2018

作者： Zheng, Zhe Qiao, Lei Wang, Liang Cui, Wenpeng Guo, Jinghong Research Department of Smart Chip Global Energy Interconnection Research Institute Co. Ltd Beijing China State Grid Key Laboratory of Information and Network Security State Grid Laboratory of Electric Power Communication Network Technology Beijing China

ISBN: (纸本)9781538641316

In response to the application and requirements of all things seamless interconnection, International Institute of Electrical and Electronics Engineers (IEEE) has put forward a new generation of standard 802.11 ah, working in Sub-1GHz frequencies, achieving low power consumption and larger wireless local area network coverage. It improves the performance of Wi-Fi which easily affected by the building block, transmission distance and coverage. The new features of 802.11ah makes it more suitable for use in the smart grid. Intelligent substation adopts advanced, reliable, integrated and environment-friendly intelligent equipment. It supports grid real-time controlling, smart adjustment, online analysis and decision-making, collaboration and interaction. All the basic operations, including the information collection, measurement, control, protection, metering and monitoring, are taken automatically. In this paper, the feasibility of the 802.11ah wireless communication applying in intelligent substation is discussed. Besides, the actual performance of 802.11ah module prototype in 110kV substation has been tested. The results are analyzed, further studies and improvements are suggested. © 2018 IEEE.

关键词： Internet of things

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An improved TPSN algorithm based on doze mechanism 2

An improved TPSN algorithm based on doze mechanism

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2nd IEEE International Conference on Energy Internet, ICEI 2018

作者： Cui, Wenpeng Zheng, Zhe Qiao, Lei Zhang, Weilong Wang, Liang Research Department of Smart Chip Global Energy Interconnection Research Institute Co. Ltd Beijing China State Grid Key Laboratory of Information and Network Security State Grid Laboratory of Electric Power Communication Network Technology Beijing China

ISBN: (纸本)9781538641316

With the rapid development of wireless sensor networks, the precision of time synchronization between nodes is becoming increasingly attractive. However, low cost, low power, low technology and other requirements restrict the use of synchronization algorithms in wireless sensor networks. TPSN time synchronization algorithm is a two-way synchronization algorithm, which is widely used in wireless sensor network. But due to the media access mechanism and the channel stability of the wireless sensor network, the standard TPSN algorithm can not meet the requirement of high precision of time synchronization. In this paper, the standard TPSN algorithm have been improved based on doze mechanism. Under the control of the central node, the nodes are doze and wake up sporadically to help with getting the transmission delay accurately. Thus, the time synchronization precision between each node is improved and the overall network power consumption is reduced. The experimental results show that the improved TPSN algorithm can effectively improve the accuracy of time synchronization. © 2018 IEEE.

关键词： Synchronization

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Semantic-Enhanced Static Vulnerability Detection in Baseband Firmware

Semantic-Enhanced Static Vulnerability Detection in Baseband...

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International Conference on Software Engineering (ICSE)

作者： Yiming Liu Cen Zhang Feng Li Yeting Li Jianhua Zhou Jian Wang Lanlan Zhan Yang Liu Wei Huo Institute of Information Engineering CAS School of Cyber Security UCAS Beijing China Key Laboratory of Network Assessment Technology CAS Beijing Key Laboratory of Network Security and Protection Technology Nanyang Technological University Singapore

ISBN: (数字)9798400702174

ISBN: (纸本)9798350382143

Cellular network is the infrastructure of mobile communication. Baseband firmware, which carries the implementation of cellular network, has critical security impact on its vulnerabilities. To handle the inherent complexity in cellular communication, cellular protocols are usually implemented as message-centric systems, containing the common message processing phase and message specific handling phase. Though the latter takes most of the code (99.67%) and exposed vulnerabilities (74%), it is rather under-studied: existing detectors either cannot sufficiently analyze it or focused on analyzing the former phase. To fill this gap, we proposed a novel semantic-enhanced static vulnerability detector named BVFinder focusing on message specific phase vulnerability detection. Generally, it identifies a vulnerability by locating whether a predefined sensitive memory operation is tainted by any attacker-controllable input. Specifically, to reach high automation and preciseness, it made two key improvements: a semantic-based taint source identification and an enhanced taint propagation. The former employs semantic search techniques to identify registers and memory offsets that carry attacker-controllable inputs. This is achieved by matching the inputs to their corresponding message and data types using textual features and addressing patterns within the assemblies. On the other hand, the latter technology guarantees effective taint propagation by employing additional indirect call resolution algorithms. The evaluation shows that BVFinder outperforms the state-of-the-art detectors by detecting three to four times of amount of vulnerabilities in the dataset. Till now, BVFinder has found four zero-day vulnerabilities, with four CVEs and 12,410 USD bounty assigned. These vulnerabilities can potentially cause remote code execution to phones using Samsung shannon baseband, affecting hundreds of millions of end devices.

关键词： Cellular networks Codes Baseband Automation Semantic search Detectors Registers

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RDGFuzz: A directed greybox fuzzing optimization method based on Rich-Branch nodes 6

RDGFuzz: A directed greybox fuzzing optimization method base...

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6th International Conference on Electronic Information technology and Computer Engineering, EITCE 2022

作者： Wu, Zejun Lu, Li Jia, Qiong Chen, Zhihao State Key Laboratory of Mathematical Engineering and advanced Computing Zheng zhou China National Local Joint Engineering Laboratory of Network Space Security Technology Zheng zhou China Beijing Institute of Computer Technology and Application BeiJing China

ISBN: (纸本)9781450397148

Directed fuzzing technology is one of the key technologies to quickly reach a specific location of software, and to conduct targeted testing or bug recurrence. However, directed fuzzing technology has some problems, such as unreasonable seed energy allocation, low code coverage and incomplete testing. To solve the above problems, this paper proposes an optimization method of directed fuzzing based on Rich-Branch nodes. In this method, the concept of Rich-Branch nodes is defined and the algorithm of extracting Rich-Branch nodes is given. The optimization method collects the coverage information of the target program in the running process, calculates the weights of covered functions and nodes in real time by combining CG and CFG of the target program, and generates a list of Rich-Branch nodes. According to the weights of Rich-Branch nodes, the seed energy allocation algorithm of AFLGo is optimized and improved. Compared with AFLGo, this optimization method improves the average code coverage of each targeted point by 56.79%, and has the same target reaching ability as AFLGo. © 2022 Association for Computing Machinery.

关键词： Software testing

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An integrative model and system for detecting NATted hosts

An integrative model and system for detecting NATted hosts

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2009 International Conference on Information Engineering and Computer Science, ICIECS 2009

作者： Zhu, Hongliang Li, Rui Xin, Yang Yang, Yixian Hu, Zhengming Key Laboratory of Network and Information Attack and Defence Technology of MOE Beijing University of Posts and Telecommunications China Information Security Center State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications China National Engineering Laboratory for Disaster Backup and Recovery Beijing University of Posts and Telecommunications China

ISBN: (纸本)9781424449941

The address non-transparency of NAT (network Address Translation) device is a great challenge for managing and monitoring the network. Now a lot of problems exist in various detection technologies for obtaining the number of NATed hosts, which can't meet the need of managing and monitoring network. This paper analyzes popular detection technologies for detecting the number of NATed hosts in detail, divides them into active algorithms and passive algorithms, summarizes the advantages and disadvantages of each algorithm, and accordingly puts forward an integrative model and system. At first end users are classified according to user states, then the system makes use of passive algorithms to determine user type, after that utilizes active algorithms to calculate the number of NATed hosts exactly. This detection system has good scalability and hierarchy and can makes a new detection algorithm integrated easily, moreover it improves the accuracy of detection and avoids normal user experience to be interrupted. ©2009 IEEE.

关键词： Active algorithm Integrative model NAT network monitoring Passive algorithm

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