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    FEATURE TOPIC: FUNDAMENTAL COMMUNICATIONS THEORIES AND SIGNAL PROCESSING TECHNIQUES FOR AMORPHOUS CELLULAR SYSTEMS
  • FEATURE TOPIC: FUNDAMENTAL COMMUNICATIONS THEORIES AND SIGNAL PROCESSING TECHNIQUES FOR AMORPHOUS CELLULAR SYSTEMS
    Shiwei Jia, Yuan Ai, Zhongyuan Zhao, Mugen Peng, Chunjing Hu
    2016, 13(12): 1-14.
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    In order to alleviate capacity constraints on the fronthaul and decrease the transmit latency, a hierarchical content caching paradigm is applied in the fog radio access networks (F-RANs). In particular, a specific cluster of remote radio heads is formed through a common centralized cloud at the baseband unit pool, while the local content is directly delivered at fog access points with edge cache and distributed radio signal processing capability. Focusing on a downlink F-RAN, the explicit expressions of ergodic rate for the hierarchical paradigm is derived. Meanwhile, both the waiting delay and latency ratio for users requiring a single content are exploited. According to the evaluation results of ergodic rate on waiting delay, the transmit latency can be effectively reduced through improving the capacity of both fronthaul and radio access links. Moreover, to fully explore the potential of hierarchical content caching, the transmit latency for users requiring multiple content objects is optimized as well in three content transmission cases with different radio access links. The simulation results verify the accuracy of the analysis, further show the latency decreases significantly due to the hierarchical paradigm.
  • FEATURE TOPIC: FUNDAMENTAL COMMUNICATIONS THEORIES AND SIGNAL PROCESSING TECHNIQUES FOR AMORPHOUS CELLULAR SYSTEMS
    Jiangang Wen, Jingyu Hua, Sunan Li, Kai Zhou, Dongming Wang
    2016, 13(12): 15-24.
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    In the forthcoming 5G systems, new technologies, such as amorphous networks and non-orthogonal filter bank multicarriers (FBMC), provide an effective way to accommodate high-rate transmissions. Meanwhile, the prototype filter affects the adjacent channel interference, and therefore is important for FBMC systems. Besides, once the amorphous network is taken into account, the requirement for interference controlmust be much stricter. Accordingly, this paper focuses on the design of prototype filter with better ability of interference controlling, where we exploit the nonlinear phase FIR filter (NLPFF) instead of traditional linear phase FIR filter (LPFF) to achieve more optimization spaces under a small sacrifice of linear phase. In ourdesigns, both the amplitude and phase responsesare handled independently to approach the stopband performance enhancements, in while the nearly perfect reconstruction (NPR) conditionsare relaxed by pre-specified thresholds. Computer simulations confirm the effectiveness of the NLPFF designs, and demonstrate the advantages of the proposed NLPFF in FBMC applications.
  • FEATURE TOPIC: FUNDAMENTAL COMMUNICATIONS THEORIES AND SIGNAL PROCESSING TECHNIQUES FOR AMORPHOUS CELLULAR SYSTEMS
    Han Hu, Hong Wang, Qi Zhu, Ziyu Pan
    2016, 13(12): 25-36.
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    A K-tier uplink heterogeneous cellular network is modelled and analysed by accounting for both truncated channel inversion power control and biased user association. Each user has a maximum transmit power constraint and transmits data when it has sufficient transmit power to perform channel inversion. With biased user association, each user is associated with a base station (BS) that provides the maximum received power weighted by a bias factor, but not their nearest BS. Stochastic geometry is used to evaluate the performances of the proposed system model in terms of the outage probability and ergodic rate for each tier as functions of the biased and power control parameters. Simulations validate our analytical derivations. Numerical results show that there exists a trade-off introduced by the power cut-off threshold and the maximum user transmit power constraint. When the maximum user transmit power becomes a binding constraint, the overall performance is independent of BS densities. In addition, we have shown that it is beneficial for the outage and rate performances by optimizing different network parameters such as the power cut-off threshold as well as the biased factors.
  • WIRELESS COMMUNICATIONS
  • WIRELESS COMMUNICATIONS
    Lusheng Wang, Yamei Wang, Wenqiang Chen, Caihong Kai, Liaoyuan Wu
    2016, 13(12): 37-48.
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    To mitigate interference on cell-edge users and improve fairness of the whole system, dynamic inter-cell interference coordination (ICIC) is one of the promising solutions. However, traditional dynamic ICIC is considered as an NP-hard problem and power variability further adds another dimension to this joint optimization issue, making it even more difficult to quickly reach a near-optimal solution. Therefore, we theoretically obtain the closed-form expression of the near-optimal power allocation ratio for users in adjacent cells paired in the same resource block and interfere each other, so that the total utility corresponding to α-fairness is maximized. Dynamic ICIC using this closed-form solution could improve user fairness without causing an increment of the computational complexity. Numerical results show that, compared with the schemes using identical power for different users, our method does not obviously degrade the system’s average spectral efficiency.
  • WIRELESS COMMUNICATIONS
    Hao Zeng*, Zeeshan Ahmad, Jianwen Zhou, Qiushi Wang, Ya Wang
    2016, 13(12): 49-58.
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    In this paper, a novel DOA estimation methodology based upon the technology of adaptive nulling antenna is proposed. Initially, the nulling antenna obtains the weight vector by LMS algorithm and power inversion criterion.Afterwards, reciprocal of the antenna pattern is defined as the spatial spectrum and the extracted peak values are corresponded to the estimated DOA. Through observation of the spectrum and data analysis of variable steps and SNRs, the simulation results demonstrate that the proposed method can estimate DOA above board. Furthermore, the estimation error of the proposed technique is directly proportional to step size and is inversely proportional to SNR. Unlike the existing MUSIC algorithm, the proposed algorithm has less computational complexity as it eliminates the need of estimating the number of signals and the eigenvalue decomposition of covariance matrix. Also it outperforms MUSIC algorithm, the recently proposed MUSIC-Like algorithm and classical methods by achieving better resolution with narrow width of peaks.
  • WIRELESS COMMUNICATIONS
    Xin Liu, Feng Li, Weidang Lu
    2016, 13(12): 59-68.
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  • WIRELESS COMMUNICATIONS
    Lingwen Zhang, Chang Liu, Jiayi Zhang, Faen Wu, Wenkao Yang
    2016, 13(12): 69-78.
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    Radio propagation in dense and super dense wireless networks as well as indoor-to-outdoor picocell networks can have multiple line-of-sight or multiple specular components. The performance of a dual-hop decode-and-forward relaying system over multiple specular components fading channels (MSCC)with multiple Rayleigh distributed co-channel interferers in an interference-limited environment is investigated. The MSCC fading model is designed to allow direct and meaningful comparisons to be made between line-of-sight channels and non-line-of-sight channels, with exact parameter correspondences. Comparisons of outage and bit error performance between Nakagami-m/Rayleigh and MSCC/Rayleigh fading environments show that the MSCC model is needed to describe line-of-sight channels that cannot be accurately modeled by the Nakagami-m, or other fading models.
  • COMMUNICATION NETWORKS
  • COMMUNICATION NETWORKS
    Guowei Zhai, Lin Tian, Yiqing Zhou, Qian Sun, Jinglin Shi
    2016, 13(12): 79-89.
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    The centralized radio access cellular network infrastructure based on centralized Super Base Station(CSBS) is a promising solution to reduce the high construction cost and energy consumption of conventional cellular networks. With CSBS, the computing resource for communication protocol processing could be managed flexibly according the protocol load to improve the resource efficiency. Since the protocol load changes frequently and may exceed the capacity of processors, load balancing is needed. However, existing load balancing mechanisms used in data centers cannot satisfy the real-time requirement of the communication protocol processing. Therefore, a new computing resource adjustment scheme is proposed for communication protocol processing in the CSBS architecture. First of all, the main principles of protocol processing resource adjustment is concluded, followed by the analysis on the processing resource outage probability that the computing resource becomes inadequate for protocol processing as load changes. Following the adjustment principles, the proposed scheme is designed to reduce the processing resource outage probability based onthe optimized connected graph which is constructed by the approximate Kruskal algorithm. Simulation results show that compared with the conventional load balancing mechanisms, the proposed scheme can reduce the occurrence number of inadequate processing resource and the additional resource consumption of adjustment greatly.
  • COMMUNICATION NETWORKS
    Zhaoming Guo, Yi Jiang, Shihua Bi
    2016, 13(12): 90-96.
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    In the paper, we illustrate the importance of the concept of mobile network computer from a technological perspective. Because of the usefulness of mobile network computers, with the growth of the Internet of things, mobile network computers may include not only TV box audio-visual equipment, wireless household appliances, and mobile communication equipment, but may also include devices such as intelligent foot rings, smart watches, smart glasses, smart shoes and smart coats. Considering the different types of networks, e.g. IP multimedia Subsystem (IMS), we explain why some network elements are inaccurate and misleading from a technological perspective. We aim to popularize the concept of mobile network computers for its accuracy and importance, which better define modern mobile terminals and reflects the nature of multiple mobile terminals based on the structure of their integrated computers and the capabilities of processing multimedia. In the computer and Internet age, network computers and mobile network computers are the main terminals of fixed and mobile networks, respectively. Therefore, based on the concept of mobile network computers, we discuss the future of information society.
  • COMMUNICATION NETWORKS
    Shichao Liu, Fuxi Zhu, Huajun Liu, Zhiqiang Du
    2016, 13(12): 97-106.
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    A large number of community discovery algorithms have been proposed in the last decade. Recently, the sharp increase of network scale has become a great challenge for traditional community discovery algorithms. Label propagation algorithm is a semi-supervised machine learning method, which has linear time complexity when coping with large scale networks. However, the output result has less stability and the quality of the output communities still remains to be improved. Therefore, we propose a novel coreleader based label propagation algorithm for community detection called CLBLPA. Firstly, we find core leaders of potential community by using a greedy method. Then we utilize the label influence potential to guide the process of label propagation. Thus we can accelerate the convergence of algorithm and improve the stability of the output. Experimental results on synthetic datasets and real networks show that CLBLPA can significantly improve the quality of the output communities.
  • COMMUNICATION NETWORKS
    Ke Xiong, Yu Zhang, Yueyun Chen, Xiaofei Di
    2016, 13(12): 107-119.
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    This paper investigates the simultaneous wireless information and powertransfer (SWIPT) for network-coded two-way relay network from an nformation-theoretic perspective,where two sources exchange information via an SWIPT-aware energy harvesting (EH) relay. We present a power splitting (PS)-based two-way relaying (PS-TWR) protocol by employing the PS receiver architecture. To explore the system sum rate limit with data rate fairness, an optimization problem under total power constraint is formulated. Then,some explicit solutions are derived for the problem. Numerical results show that due to the path loss effect on energy transfer, with the same total available power, PS-TWR losses some system performance compared with traditional non-EH two-way relaying, where at relatively low and relatively high signalto-noise ratio (SNR), the performance loss is relatively small. Another observation is that,in relatively high SNR regime, PS-TWR outperforms time switching-based two-way relaying (TS-TWR) while in relatively low SNR regime TS-TWR outperforms PS-TWR. It is also shown that with individual available power at the two sources, PS-TWR outperforms TS-TWR in both relatively low and high SNR regimes.
  • COMMUNICATION NETWORKS
    Mohammad Mostafavi, Javad Musevi Niya, Hosein Mohammadi, Behzad Mozaffari Tazehkand
    2016, 13(12): 120-131.
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    Resource allocation in the context of OFDMA-based systems is challenging, given a combinatorial nature of the problem. In the context of IEEE 802.16 systems this problem is further exacerbated by additional constraints that are faced with its two dimensional frame nature. The main challenges associated with resource allocation in these systems are: mapping the allocated bandwidth resources to users in this two dimensional frame, power and frequency allocation, and QoS guarantee. This optimization problem can usually be solved by an iterative algorithm. The solutions proposed have a constant step size in iterations which causes a long convergence time. For this reason, the solutions proposed are not applicable in IEEE 802.16 systems. In this paper we propose a novel resource allocation algorithm in IEEE 802.16 systems which has an adaptive step size in iterations while taking into account the minimum rate guarantee for users.
  • COMMUNICATION NETWORKS
    Haitao Zhao, Aiqian Du, Hongbo Zhu, Dapeng Li, Nanjie Liu
    2016, 13(12): 132-138.
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    In order to improve the broadcast reception rates of beacon messages in vehicle ad-hoc networks,a conclusion that the relationship between collision probability and minimum contention window size and the relationship between expiration probability and minimum window size was reached by building a Markov model. According to this conclusion, a back-off algorithm based on adjusting the size of minimum contention window called CEB is proposed, and this algorithm is on the basis of the differential size between the number of expiration beacons and preset threshold. Simulations were done to compare the performance of CEB with that of RBEB and BEB, and the results show that the performance of the new proposed algorithm is better than that of RBEB and BEB.
  • OPTICAL COMMUNICATIONS
  • OPTICAL COMMUNICATIONS
    Yubo Wang, Bei Gong, Mowei Gong
    2016, 13(12): 139-149.
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  • SERVICES AND APPLICATIONS
  • SERVICES AND APPLICATIONS
    Rahat Ullah, Bo Liu, Qi Zhang, Yousaf Khan, Amjad Ali, Qinghua Tian, Feng Tian, M. Saad Khan, Tabinda Salam, Sibghat Ullah, Lijia Zhang, Xiangjun Xin
    2016, 13(12): 150-161.
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    A new scheme is offered for minimizing carrier Rayleigh backscattering (CRB) in single feeder fiber based wavelength division multiplexed passive optical network (WDM-PON). The proposed scheme is based on single side band carrier suppressed (SSB-CS) signal, both at network and receiver sides, used for the first time at optical line terminal (OLT) and optical network unit (ONU) sides. We use dual-drive Mach-zehnder modulator (DD-MZM) for generating SSB-CS signals, which decreases the expense per bit in full transmission. SSB-CS mitigates CRB, both at OLT and ONU sides, because of having no chance of reflections from the carrier. Since no extra dedicated RF or laser source is used at ONU side, we thus achieve cost effective colorless WDM-PON system. Suppressed signals from four channels, each of 10 Gbps, are multiplexed before injecting into the fiber span of 25 km at OLT. At ONU side, half of the downlink power is used for re-modulating the data signal. The simulation results show an error free transmission. Moreover, the detailed power budget calculations show that the proposed scheme can be sought out for splitting ratio up to 128. Hence it offers enough system’s margin for unseen losses.
  • SERVICES AND APPLICATIONS
    Lanshan Zhang, Xi Ding, Ye Tian, Xiangyang Gong, Wendong Wang
    2016, 13(12): 162-175.
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    With the rapid popularization of social applications, various kinds of social media have developed into an important platform for publishing information and expressing opinion. Detecting hidden topics from the huge amount of user-generated contents is of great commerce value and social significance. However traditional text analysis approachesonly focus on the statistical correlation between words, but ignore the sentiment tendency and the temporal properties which may have great effects on topic detection results. This paper proposed a Dynamic Sentiment-Topic (DST) model which can not only detect and track the dynamic topics but also analyze the shift of public’s sentiment tendency towards certain topic.Expectation-Maximization algorithm was used in DST model to estimate the latent distribution, and we used Gibbs sampling method to sample new document set and update the hyper parameters and distributions.Experiments are conducted on a real dataset and the results show that DST model outperforms the existing algorithms in terms of topic detection and sentiment accuracy.
  • SERVICES AND APPLICATIONS
    Xinyu Li, Jingy Xu, Zhenfeng Zhang, Dengguo Feng
    2016, 13(12): 176-188.
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    The Transport Layer Security (TLS) protocol is the most important standard on the Internet for key exchange. TLS standard supports many additional handshake modes such as resumption and renegotiation besides the full handshake. The interaction and dependence of different modes may lead to some practical attacks on TLS. In 2014, Bhargavan et al. described a triple handshake attack on TLS 1.2 by exploiting the sequential running of three different modes of TLS, which can lead to a client impersonation attack after the third handshake. Subsequently, TLS 1.2 was patched with the extended master secret extension of RFC 7627 to prevent this attack. In this paper we introduce a new definition of “uniqueness” and present a renegotiable & resumable ACCE security model. We identify the triple handshake attack within the new model, and furthermore show TLS with the proposed fix can be proven secure in our model.
  • SERVICES AND APPLICATIONS
    Kexin Hu, Zhenfeng Zhang
    2016, 13(12): 189-198.
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    FIDO (Fast IDentity Online) Alliance proposed a set of standard in 2014 for change the nature of online authentication. By now, it has drawn attention from many companies, including Google, VISA, Intel etc. In this paper, we analyze the FIDO UAF (Universal Authentication Framework) Protocol, one of the two sets of specifications in the standard. We first present protocols’ cryptographic abstractions for the registration and authentication protocols of the FIDO UAF. According to the abstractions, we discuss on selected security goals presented in the standard to study UAF security properties. We also propose three attacks, which the first two are based on an assumption that an attacker can corrupt the software installed on the user device, and the third is based on two users sharing a FIDO roaming authenticator. The results of the attacks are to impersonate the legitimate user to pass the online authentication.
  • SERVICES AND APPLICATIONS
    Xindi Ma, Jianfeng Ma, Hui Li, Qi Jiang, Sheng Gao
    2016, 13(12): 199-215.
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    The ubiquity of mobile devices have promoted the prosperity of mobile crowd systems, which recruit crowds to contribute their resources for performing tasks. Yet, due to the various resource consumption, the crowds may be reluctant to join and contribute information. Thus, the low participation level of crowds will be a hurdle that prevents the adoption of crowdsourcing. A critical challenge for these systems is how to design a proper mechanism such that the crowds spontaneously act as suppliers to contribute accurate information. Most of existing mechanisms ignore either the honesty of crowds or requesters respectively. In this paper, considering the honesty of both, we propose a game-based incentive mechanism, namely RTRC, to stimulate the crowds to contribute accurate information and to motivate the requesters to return accurate feedbacks. In addition, an evolutionary game is designed to model the dynamic of user-strategy selection. Specially, the replicator dynamic is applied to model the adaptation of strategy interactions taking into account the dynamic nature in time dependence and we also derive the evolutionarily stable strategies (ESSs) for users. Finally, empirical results over the simulations show that all the requesters and suppliers will select honest strategy to maximize their profit.
  • SERVICES AND APPLICATIONS
    Chenyu Li, Jun Liu, Shuxin Ouyang
    2016, 13(12): 216-233.
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    Understanding the characteristics and predicting the popularity of the newly published online videos can provide direct implications in various contexts such as service design, advertisement planning, network management and etc. In this paper, we collect a real-world large-scale dataset from a leading online video service provider in China, namely Youku. We first analyze the dynamics of content publication and content popularity for the online video service. Then, we propose a rich set of features and exploit various effective classification methods to estimate the future popularity level of an individual video in various scenarios. We show that the future popularity level of a video can be predicted even before the video’s release, and by introducing the historical popularity information the prediction performance can be improved dramatically. In addition, we investigate the importance of each feature group and each feature in the popularity prediction, and further reveal the factors that may impact the video popularity. We also discuss how the early monitoring period influences the popularity level prediction. Our work provides an insight into the popularity of the newly published online videos, and demonstrates promising practical applications for content publishers, service providers, online advisers and network operators.
  • SERVICES AND APPLICATIONS
    Yanan Wang, Xiuzhen Chen, Jianhua Li, Wanyu Huang
    2016, 13(12): 234-249.
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    the existing information diffusion models focus on analyzing the spatial distribution of certain pieces of messages in social networks. However, these conventional models ignored another important characteristic of diffusion: gradually changing of message contents due to the ‘new’ and ‘comment’ mechanisms. A novel genetic-algorithm-based information evolution model is proposed to reproduce both the diffusion and development process of information in social networks. This model firstly proposes a five-tuple to represent three types of topics: independent, competitive and mutually exclusive. Furthermore, it adopts mutation operator and forms new crossover and mutation rules to simulate four typical interactions between individuals, which bring the advantage of reproducing the information evolution process in both popularity and content.A series of experiments tested on public datasets demonstrate that: 1) independent and competitive topics of information rarely affect each other while mutually exclusive topics significantly suppress the diffusion processes of each other; 2) lower mutation probability leads to decreasing of final information amount. The experimental results show that our evolution model is more reasonable and feasible in demonstrating the evolution of information in social networks.
  • SERVICES AND APPLICATIONS
    Gongan Qiu, Shibing Zhang*, Xiaoge Zhang
    2016, 13(12): 250-260.
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    Based on the service characteristics and the sensing ability for secondary users, a joint optimization scheme of spectrum detection and allocation is investigated to expand the available sensing region and allocate the QoS-specified channels. On the aspect of spectrum detection, due to the available detection index with the global detection metrics, cooperation thresholds are adaptively adjusted to select the cooperative model for maximizing the available sensing region. On the aspect of spectrum allocation, for different service category, the idle channels are efficiently allocated that depend on their stability and available bandwidth. Meanwhile, based on the requested rates defined by fuzzy theory, the secondary users can be divided into two categories, i.e.,delay sensitive service and reliability sensitive service. Finally, the QoS-specified channels from the targeted spectrum subset are allocated to secondary users. Simulation results show that our proposed algorithm can not only expand the available sensing region,but also decrease the outage probability of delay sensitive services. Additionally, it enables stable power consumption in the time-variation channel.
  • SERVICES AND APPLICATIONS
    Ru Huo, Renchao Xie, Hengyang Zhang, Tao Huang, Yunjie Liu
    2016, 13(12): 261-276.
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    Information-centric networking (ICN) aims to improve the efficiency of content delivery and reduce the redundancy of data transmission by caching contents in network nodes. An important issue is to design caching methods with better cache hit rate and achieve allocating on-demand. Therefore, an in-network caching scheduling scheme for ICN was designed, distinguishing different kinds of contents and dynamically allocating the cache size on-demand. First discussing what was appropriated to be cached in nodes, and then a classification about the contents could be cached was proposed. Furthermore, we used AHP to weight different contents classes through analyzing users’ behavior. And a distributed control process was built, to achieve differentiated caching resource allocation and management. The designed scheme not only avoids the waste of caching resource, but also further enhances the cache availability. Finally, the simulation results are illustrated to show that our method has the superior performance in the aspects of server hit rate and convergence.
  • SERVICES AND APPLICATIONS
    Jian Qu, Le Minh Nguyen, Akira Shimazu
    2016, 13(12): 277-296.
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    OOV term translation plays an important role in natural language processing. Although many researchers in the past have endeavored to solve the OOV term translation problems, but none existing methods offer definition or context information of OOV terms. Furthermore, non-existing methods focus on cross-language definition retrieval for OOV terms. Never the less, it has always been so difficult to evaluate the correctness of an OOV term translation without domain specific knowledge and correct references. Our English definition ranking method differentiate the types of OOV terms, and applies different methods for translation extraction. Our English definition ranking method also extracts multilingual context information and monolingual definitions of OOV terms. In addition, we propose a novel cross-language definition retrieval system for OOV terms. Never the less, we propose an auto re-evaluation method to evaluate the correctness of OOV translations and definitions. Our methods achieve high performances against existing methods.
  • BOOK REVIEW
  • BOOK REVIEW
    Jianmin Zhang
    2016, 13(12): 297-298.
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