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Pre-scan based fast handoff scheme for enterprise IEEE 802.11 networks

The Journal of China Universities of Posts and Telecommunications 2016年第6期23卷 60-67页

作者： Zhang Biao Wen Xiangming Lu Zhaoming Lei Tao Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

In IEEE 802.11 networks, many access points（APs） are required to cover a large area due to the limited coverage range of APs, and frequent handoffs may occur while a station（STA） is moving in an area covered by several APs. However, traditional handoff mechanisms employed at STAs introduce a few hundred milliseconds delay, which is far longer than what can be tolerated by some multimedia streams such as voice over Internet protocol（Vo IP）, it is a challenging issue for supporting seamless handoff service in IEEE 802.11 networks. In this paper, we propose a pre-scan based fast handoff scheme within an IEEE 802.11 enterprise wireless local area network（EWLAN） environment. The proposed scheme can help STA obtain the best alternative AP in advance after the pre-scan process, and when the handoff is actually triggered, STA can perform the authentication and reassociation process toward the alternative AP directly. Furthermore, we adopt Kalman filter to minimize the fluctuation of received signal strength（RSS）, thus reducing the unnecessary pre-scan process and handoffs. We performed simulations to evaluate performance, and the simulation results show that the proposed scheme can effectively reduce the handoff delay.

关键词： fast handoff IEEE 802.11 networks handoff delay enterprise WLAN

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Best-effort service QoE assessment using visual information based Weber-Fechner law

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The Journal of China Universities of Posts and Telecommunications 2016年第2期23卷 38-45页

作者： Guan Wanqing Wang Luhan Lu Zhaoming Wen Xiangming Chen Xin Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

Quality of experience（QoE） has been one of the most important factors for service providers and operators to develop and deploy services. Previous works have shown that Weber-Fechner law（WFL） can be used to promote the accuracy of best-effort（BE） services＇ QoE assessment. In this paper, based on WFL, we take a deep insight into the visual information of BE services and its role in WFL, especially in web browsing services, and propose an enhanced QoE assessment model for BE services by taking the visual information into account. Both images and texts visual information are extracted and combined to get the visual information for web pages. Finally, a subjective experiment is performed to validate performance of proposed QoE assessment model, which shows that it performs better than traditional WFL based model.

关键词： QoE assessment Weber-Fechner law best-effort service visual information

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Analysis of Malware Application Based on Massive network Traffic

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China Communications 2016年第8期13卷 209-221页

作者： Xiaolin Gui Jun Liu Mucong Chi Chenyu Li Zhenming Lei Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

Security and privacy issues are magnified by velocity, volume, and variety of big data. User's privacy is an even more sensitive topic attracting most people's attention. While XcodeGhost, a malware of i OS emerging in late 2015, leads to the privacy-leakage of a large number of users, only a few studies have examined XcodeGhost based on its source code. In this paper we describe observations by monitoring the network activities for more than 2.59 million i Phone users in a provincial area across 232 days. Our analysis reveals a number of interesting points. For example, we propose a decay model for the prevalence rate of Xcode Ghost and we find that the ratio of the infected devices is more than 60%; that a lot of popular applications, such as Wechat, railway 12306, didi taxi, Youku video are also infected; and that the duration as well as the traffic volume of most Xcode Ghost-related HTTP-requests is similar with usual HTTP-request which makes it difficult to be found. Besides, we propose a heuristic model based on fingerprint and its web-knowledge to identify the infected applications. The identifying result shows the efficiency of this model.

关键词： Xcode Ghost big data network security applications identification

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Joint User Association and Power Allocation for multimedia services in coded cache-enabled HetNets

Joint User Association and Power Allocation for multimedia s...

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International Symposium on Personal, Indoor, and Mobile Radio Communications

作者： Fangfang Yin Anyue Wang Zhilong Zhang Danpu Liu Beijing Laboratory of Advanced Information Network Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing 100876 China

ISBN: (纸本)9781538660102

In order to obtain the worthwhile gain in coverage and the capacity required by future mobile services, heterogeneous networks (HetNets) are being considered as one of the most promising solutions. However, the ultra-dense deployment of small base stations (ud-SBSs) would significantly increase energy consumption (EC), which becomes particularly severe when meeting explosive growth of multimedia services. Proper user association (UA) and power allocation (PA) are both crucial to achieve desirable energy-saving performance in HetNets. In view of these, this paper investigates the joint UA and PA optimization problem for multimedia services in cache-enabled HetNets. The aim is to minimize the total power consumption under certain quality-of-service (QoS) requirement and maximum power limit. A non-convex mixed integer programming optimization problem is formulated. To solve the problem, a heuristic algorithm based on matching game is proposed. Numerical results demonstrate that the proposed algorithm yields a performance improvement in terms of the power consumption.

关键词： ud-SBSs EC UA

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Expected Q-learning for self-organizing resource allocation in LTE-U with downlink-uplink decoupling 23

Expected Q-learning for self-organizing resource allocation ...

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23rd European Wireless Conference, EW 2017

作者： Hu, Ye MacKenzie, Richard Hao, Mo Beijing Laboratory of Advanced Information Network Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing100876 China BT TSO Adastral Park Ipswich United Kingdom Tsinghua SEM Advanced ICT Lab Beijing100084 China

ISBN: (纸本)9783800744268

Exponentially growing demand on mobile data facilitates the need to increase spectrum efficiency and also to gain access to additional spectrum bands. LTE-U provides a way for LTE service to be provided, in some regulatory areas, using a combination of licensed and unlicensed spectrum. In this paper, we consider the resource allocation problem in LTE-U networks with downlink-uplink decoupling (DUDe) technique. Here, the spectrum allocation problem is formulated as a game theoretic model which incorporates user association, spectrum allocation, and load balancing. We propose a decentralized expected Q-learning algorithm to solve this game. Using the proposed algorithm, the base stations can autonomously choose their optimal spectrum allocation schemes based on only limited information from the networks. It is shown that the proposed algorithm converges to a stationary mixed-strategy distribution which constitutes a mixed strategy Nash equilibrium for the studied game. Simulation results show the proposed Q-learning algorithm yields up to 12.7% and 51.1% improvement in terms of total rate, compared to traditional Q-learning and nearest neighbor algorithms, respectively. Furthermore, it is shown that the proposed Q-learning algorithm always converges to a mixed Nash equilibrium, and need 19% less time to coverage compared to traditional Qlearning. © VDE VERLAG GMBH · Berlin · Offenbach.

关键词： Reinforcement learning

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A Sparse Superposition Multiple Access Scheme and Performance Analysis for 5G Wireless Communication systems

A Sparse Superposition Multiple Access Scheme and Performanc...

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IEEE International Conference on Communications in China Workshops (ICCC)

作者： Kai Zhang Jin Xu Changchuan Yin Weiqiang Tan Chunguo Li Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China School of Computer and Communication Engineering Zhengzhou University of Light Industry Zhengzhou China School of Computer Science Guangzhou University Guangzhou China National Communications Research Laboratory Southeast University Nanjing China

ISBN: (纸本)9781538670125;9781538670118

Orthogonal multiple access (OMA) is widely employed in traditional cellular wireless communication systems due to a low-complexity receiver is needed. However, multiple access scheme with higher spectral efficiency and the capability of access more users than OMA scheme is preferred for the future wireless communication systems. In this work, we propose a non-orthogonal multiple access scheme called sparse superposition multiple access (SSMA) by superposing more users to a limited number of time-frequency resource for the uplink transmission in the fifth generation (5G) wireless communication systems. Moreover, we design two sparse superposition matrices (SSMs) for 150% and 200% overloaded SSMA scheme. Then, a low complexity belief propagation detection and decoding algorithm based multiple user detection is proposed. Furthermore, we utilize extrinsic information transfer chart to analyze the superiority of the proposed SSMs theoretically and the numerical results show that the proposed SSM with an overload of 150% has a gain of about 1 dB compared to the existing scheme. Finally, simulation results demonstrate that the proposed scheme outperforms the traditional OMA scheme and the existing scheme significantly.

关键词： Multiuser detection Wireless communication Conferences convergence Maximum likelihood decoding Message passing Receivers

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Asymmetrical and direct current biased optical OFDM for visible light communication with dimming control

Asymmetrical and direct current biased optical OFDM for visi...

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2017 IEEE International Conference on Communications Workshops, ICC Workshops 2017

作者： Yin, Namei Guo, Caili Yang, Yang Luo, Pengfei Chunyan, Feng Beijing Laboratory of Advanced Information Networks Beijing University of Posts and Telecommunications China Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications China Research Department of HiSilicon Huawei Technologies Co. Ltd Beijing China

ISBN: (纸本)9781509015252

In visible light communication (VLC) systems, optical orthogonal frequency division multiplexing (O-OFDM) is an appealing modulation. Among many proposed O-OFDM schemes, both direct current biased O-OFDM (DCO-OFDM) and asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) are widely used. Since VLC needs to take the dual requirements of illumination and communication into account, different dimming levels are often required. For high and low dimming level scenarios, system with ACO-OFDM normally has a better spectral efficiency performance than system with DCO-OFDM due to the smaller clipping noise. However, regarding the middle dimming level scenarios, the DCO-OFDM generally outperforms the ACO-OFDM. In order to improve system spectral efficiency within the wide dimming range, an asymmetrical and direct current biased optical orthogonal frequency division multiplexing (AAD-OFDM) is proposed in this paper. In AAD-OFDM based system, the modulation scheme is switched between ACO-OFDM and DCO-OFDM according to the required dimming level. Therefore, by adopting the proposed AAD-OFDM, the VLC system can fully utilize the dynamic range of LED at any dimming levels thus improving the performance. Simulation results show that the proposed scheme has high spectral efficiency within a wide dimming range. © 2017 IEEE.

关键词： Visible light communication

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Indoor visible light localization algorithm based on received signal strength ratio with multi-directional LED array

Indoor visible light localization algorithm based on receive...

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2017 IEEE International Conference on Communications Workshops, ICC Workshops 2017

作者： Lixuan, Wang Guo, Caili Luo, Pengfei Li, Qiang Beijing Laboratory of Advanced Information Networks Beijing University of Posts and Telecommunications Beijing China Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China Research Department of HiSilicon Huawei Technologies Co. Ltd Beijing China

ISBN: (纸本)9781509015252

Visible light communication (VLC) based localization is a potential candidate for indoor localization. However, since the field of view (FOV) of the photodiode (PD) is normally narrow, the PD might not be capable to detect enough LEDs to perform the triangulation algorithm. Furthermore, high directionality is a significant character in VLC, and in practice, the direction of LED is commonly fixed and able to be known for once, but the direction of the PD is commonly random. In this paper, we exploit the direction of the LED in the lamp structure design and manage to mitigate the influence of the direction of the PD in the algorithm design. A localization algorithm based on received signal strength ratio (RSSR) with multi-directional LED array (MDLA) is proposed. In addition, we introduce the coverage ratio (CR) and the average angle acceptance ratio (AAAR) to evaluate the localization scheme's coverage in location and acceptance in direction, respectively. Simulation results show that when the tilt angle of LEDs is 15°, the proposed scheme can attain the root-mean-square error (RMSE) of 0.04 m and 0.06 m in 2-D and 3-D localization, respectively, and it is more probably for it to obtain enough lamps compared to the conventional scheme using the triangulation algorithm with the lamp structure of a single LED. © 2017 IEEE.

关键词： Light emitting diodes

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Fine-grained analysis of cellular smartphone usage characteristics based on massive network traffic

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The Journal of China Universities of Posts and Telecommunications 2016年第3期23卷 70-75页

作者： Gui Xiaolin Liu Jun Li Chenyu Lv Qiujian Lei Zhenming Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing 100876 China

Increased adoption of smartphones leads to the explosive growth of mobile network traffic. Understanding the traffic characteristics of mobile network is important for Intemet service providers （ISPs） to optimize network resources. In this paper, we conduct a detailed measurement study on the hyper text transfer protocol （HTTP） traffic characteristics of cellular network among different operating systems （OSs） as well as different device-types. Firstly, we propose a probability-based method to identify the installed OS of eacb smartphone. Then we analyze the traffic characteristics of these smartphones in terms of OS and device-type based on a dataset across 31 days （a billing cycle）. Finally, we identify the installed apps of each smartphone and compare the usage of apps on the dimensions of OS and device-type. Our measurement study provides insights for network operators to strategize priciag and resource allocation for their cellular data networks.

关键词： HTTP traffic smartphone OS device-type network measurement

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Traffic Tunnel Management in Cloud-based Flow Security system

Traffic Tunnel Management in Cloud-based Flow Security Syste...

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2017 2nd International Conference on Advanced Materials Science and Environment Engineering(AMSEE2017)

作者： Gang HE Yu-zhu CHEN Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

Considering the increasingly serious problem of Internet security recently, Cloud-based Flow Security system(CFS) has been built as a solution to the Internet security application, providing convenient and effective application and content level security for enterprise users by means of cloud services. Under the CFS system, this paper developed custom function modules to achieve unified management of network nodes and GRE tunnel between the nodes, management of the switch data forwarding, and real-time monitoring of the state of the tunnel in the control platform, accomplished the design scheme of combining the load balancing algorithm with the unified management of the tunnel, realized the efficient allocation of the network nodes in the large-scale network environment and improved the network flexibility.

关键词： Cloud-based Software Defined networking Unified management Load balancing

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