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    Guest Editorial
  • Guest Editorial
    A Survey: Several Technologies of Non-Orthogonal Transmission for 5G
    Tao Yunzheng, Liu Long, Liu Shang, Zhang Zhi
    2015, 1(10): 1-15.
    Abstract ( )   Knowledge map   Save
    One key advantage of 4G OFDM system is the relatively simple receiver implementation due to the orthogonal resource allocation. However, from sum-capacity and spectral efficiency points of view, orthogonal systems are never the achieving schemes. With the rapid development of mobile communication systems, a novel concept of non-orthogonal transmission for 5G mobile communications has attracted researches all around the world. In this trend, many new multiple access schemes and waveform modulation technologies were proposed. In this paper, some promising ones of them were discussed which include Non-orthogonal Multiple Access (NOMA), Sparse Code Multiple Access (SCMA), Multi-user Shared Access (MUSA), Pattern Division Multiple Access (PDMA) and some main new waveforms including Filter-bank based Multicarrier (FBMC), Universal Filtered Multi-Carrier (UFMC), Generalized Frequency Division Multiplexing (GFDM). By analyzing and comparing features of these technologies, a research direction of guiding on future 5G multiple access and waveform are given.
  • Guest Editorial
    A 3-D Polarization Quadrature Amplitude Modulation Method and Constellation Mapping
    SUN Xuehong*, ZHANG Haiying, ZENG Zhimin, GUO Caili
    2015, 1(10): 16-26.
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    As a new three-dimensional (3-D) modulation, Polarization Quadrature Amplitude Modulation (PQAM) can be regarded as the combination of Pulse amplitude modulation (PAM) and Quadrature Amplitude Modulation (QAM) Modulation. It can better improve the digital communication efficiency and reduce the Symbol error rate (SER) of the system than one-dimensional or two-dimensional modulation scheme. How to design a feasible constellation is the most concerned problem of PQAM currently. This paper first studies the relationship between the SER theoretical value of PQAM and the distribution of M and N, proposes a new M, N allocation scheme. Secondly, a new and straightforward design method of constructing higher-level 3-D signal constellations, which can be matched with the PQAM, and the constellation can divided into three different structures according to the ary for PQAM. Finally, the simulation results show that: in PQAM system, the modulation scheme and the constellation mapping scheme are proposed in this paper which can effectively reduce the system SER and improve the anti-noise performance of the system.
  • Guest Editorial
    QoE-Oriented Resource Allocation for Multiuser-Multiservice Femtocell Networks
    Yuan Deyu, Song Mei, Teng Yinglei, Ma Ding, Wang Xiaojun, Lu Guofeng
    2015, 1(10): 27-41.
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    The pursuit of high data rate and assurance of quality of experience (QoE) for end users represent the main goals of future wireless communication systems. By introducing MOS (Mean Opinion Score) based assessment models for different types of applications, this paper proposed novel QoE-oriented radio resource allocation (RRA) algorithms for multiuser-multiservice femtocell networks. An optimal QoE-oriented RRA strategy is first analyzed using time-sharing method which is applicable to best effort applications. RRA algorithms based on the cross-layer architecture are then proposed for all types of applications by considering parameters extracted from different layers of networking protocols. In the proposed algorithms, a priority mechanism is employed to ensure fairness. Simulation results show that the proposed algorithms can significantly improve the overall perceived quality from the users’ perspective in comparison with traditional Quality of Service (QoS) oriented algorithms.
    • CHANNEL CHARACTERIZATION AND MODELING
  • CHANNEL CHARACTERIZATION AND MODELING
    Link Maintenance Scheme for OFDM-Based Cognitive Radio Ad Hoc Networks
    Li Jingye, Luo Tao, Liu Xuelian, Yue Guangxin
    2015, 1(10): 42-51.
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    Transmission among the cognitive users (CUs)’ is always interrupted by the primary users (PUs)’ reclaim of the spectrum and the fading effect of wireless channels. To maintain reliable continuous communication among CUs, an efficient scheme for link maintenance in OFDM-based cognitive radio Ad Hoc networks is proposed in this paper. In the scheme, redundant sub-channels (RSC) are employed by CUs to tackle the outage problem caused by the PUs’ reclaim of the spectrum and wireless fading effect in the transmission. Meanwhile, backup sub-channels (BSC) are arranged to help select sub-channels with better channel quality. Additionally, to lower the overhead and improve the accuracy of the spectrum sensing, a partial sensing module is designed to enable the CUs to inherit and update the original idle spectrum list until it expires. Simulation results show that the proposed scheme can realize higher throughput and lower sensing overhead with slight reduction of the forced termination probability (FTP) performance compared to the existing approaches.
  • CHANNEL CHARACTERIZATION AND MODELING
    Polarization Projection for 3D Geometry-Based Stochastic Channel Model
    Pang Lihua, Zhang Yang, Gong Fengkui, Wang Anyi, Xiao Liyuan, Liang Xiao, Wang Qiaofeng, Li Jiandong
    2015, 1(10): 52-63.
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    Comprehensive radiation characteristics of polarized antenna are crucial in creating practical channel coefficients for next generation wireless communication system designs. Being currently supported within 3D geometry-based stochastic channel models (GSCM), field patterns are technically obtained by chamber measurement (or by its best fitting). However, in some channel related performance analysis scenarios, design insight can be crystallized better by starting the derivations with theoretical co-polarization and cross-polarization components. Specifically, these two components are mathematically linked with field patterns through the proposed polarization projection algorithm. In this manuscript, we focus on revealing the transformation criterion of polarization states between the antenna plane and the propagation plane. In practice, it makes retrieving the field patterns by electromagnetic computation possible. Meanwhile, the impact imposed by distinct antenna orientations is geometrically illustrated and consequently incorporated into the proposed algorithm. This will further facilitate flexible performance evaluation of related radio transmission technologies. Our conclusions are verified by the closed-form expression of the dipole field pattern (via an analytical approach) and by chamber measurement results. Moreover, we find that its 2D degenerative case is aligned with the definitions in 3rdgeneration partnership project (3GPP) technical report 25.996. The most obvious benefit of the proposed algorithm is to significantly reduce the cost on generating channel coefficients in GSCM simulation.
    • COMMUNICATIONS SYSTEM DESIGN
  • COMMUNICATIONS SYSTEM DESIGN
    Energy-Efficient Beamforming for Two-Tier Massive MIMO Downlink
    Xu Guozhen, Liu An, Jiang Wei, Xiang Haige, Luo Wu
    2015, 1(10): 64-75.
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    Heterogeneous networks (HetNets) consisting of macro cells with very large antenna arrays and a secondary tier of small cells with a few antennas each can well tackle the contradiction of large coverage of the network and high data rate at the hot spots. However, it is not permissible to assign orthogonal pilot sequences for all the supported users due to the large number. Hence, we propose a pilot reduction scheme based on the heterogeneous system configurations and the unique topology of this HetNet. The reusing of pilot sequences causes the presence of the contaminated channel state information (CSI) and results in receivers’ Quality of Service (QoS) outage. With the contaminated CSI, we provide an energy-efficient beamforming based on minimizing the total power consumption while keeping the QoS constraints satisfied and restricting the QoS outage probability below a given specification. By applying the approach of Bernstein approximation and semi-definite relaxation, we transform the original intractable chance constrained program to a convex problem conservatively. Numerical results show that the average power consumption of the proposed beamforming for our pilot reduction scheme is close to that of the perfect CSI case. Since our scheme will greatly compress the length of pilot sequence especially for those highly densified network with large number of small cells, it will be crucially helpful to put such two-tier massive multiple-input and multiple-output (MIMO) systems into practice.
  • COMMUNICATIONS SYSTEM DESIGN
    Full Diversity Reception Based on Dempster-Shafer Theory for Network Coding with Multiple-Antennas Relay
    Sun Yanhua, Yang Yi, Li Yonghua, Zhang Yanhua
    2015, 1(10): 76-90.
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    In this paper, a two-way relay system which achieves bi-directional communication via a multiple-antenna relay in two time slots is studied. In the multiple access (MA) phase, the novel receive schemes based on Dempster-Shafer (D-S) evidence theory are proposed at the relay node. Instead of traditional linear detection, the first proposed MIMO-DS NC scheme adopts D-S evidence theory to detect the signals of each source node before mapping them into network-coded signal. Moreover, different from traditional physical-layer network coding (PNC) based on virtual MIMO model, the further proposed MIMO-DS PNC comes from the vector space perspective and combines PNC mapping with D-S theory to obtain network-coded signal without estimating each source node signal. D-S theory can appropriately characterize uncertainty and make full use of multiple evidence source information by Dempster’s combination rule to obtain reliable decisions. In the broadcast (BC) phase, the space-time coding (STC) and antenna selection (AS) schemes are adopted to achieve transmit diversity. Simulation results reveal that the STC and AS schemes both achieve full transmit diversity in the BC phase and the proposed MIMO-DS NC/PNC schemes obtain better end-to-end BER performance and throughputs compared with traditional schemes with a little complexity increasing and no matter which scheme is adopted in the BC phase, MIMO-DS PNC always achieves full end-to-end diversity gain as MIMO-ML NC but with a lower complexity and its throughput approaches the throughput of MIMO-ML NC in high SNR regime.
  • COMMUNICATIONS SYSTEM DESIGN
    Epidemic-Like Proximity-Based Traffic Offloading
    Dong Wenxiang, Chen Jie, Yang Ying, Zhang Wenyi
    2015, 1(10): 91-107.
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    Cellular networks are overloaded due to the mobile traffic surge, and mobile social networks (MSNets) can be leveraged for traffic offloading. In this paper, we study the issue of choosing seed users for maximizing the mobile traffic offloaded from cellular networks. We introduce a gossip-style social cascade (GSC) model to model the epidemic-like information diffusion process in MSNets. For static-case and mobile-case networks, we establish an equivalent view and a temporal mapping of the information diffusion process, respectively. We further prove the submodularity in the information diffusion and propose a greedy algorithm to choose the seed users for traffic offloading, yielding a sub-optimal solution to the NP-hard traffic offloading maximization (TOM) problem. Experiments are carried out to study the offloading performance, illustrating that the greedy algorithm significantly outperforms the heuristic and random algorithms, and user mobility can help further reduce cellular load.
  • COMMUNICATIONS SYSTEM DESIGN
    A PHEMT Based Wideband LNA for Wireless Applications
    Muhammad Saad Khan, Zhang Hongxin, He Pengfei, Sulman Shahzad, Rahat Ullah
    2015, 1(10): 108-116.
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    This work is about the development of a super low noise amplifier with minimum power consumption and high gain for several wireless applications. The amplifier operates at frequency bands of 0.9-2.4 GHz and can be used in many applications like Wireless local area network (WLAN), WiFi, Bluetooth, ZigBee and Global System for mobile communications (GSM). This new design can be employed for the IEEE 802.15.4 standard in industrial, scientific and medical (ISM) Band. The enhancement mode pseudomorphic high electron mobility transistor PHEMT is used here due to its high linearity, better performance and less noisy operation. The common source inductive degeneration method is employed here to enhance the gain of amplifier. The amplifier produces a gain of more than 17 dB and noise figure of about 0.5 dB. The lower values of S11 and S22 reflect the accuracy of impedance matching network placed at the input and output sides of amplifier. Agilent Advance Design System (ADS) is used for the design and simulation purpose. Further the layout of design is developed on the FR4 substrate.
  • COMMUNICATIONS SYSTEM DESIGN
    A Novel Stateful PCE-Cloud Based Control Architecture of Optical Networks for Cloud Services
    Qin Panke, Chen Xue, Wang Lei, Wang Liqian
    2015, 1(10): 117-127.
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    The next-generation optical network is a service oriented network, which could be delivered by utilizing the generalized multiprotocol label switching (GMPLS) based control plane to realize lots of intelligent features such as rapid provisioning, automated protection and restoration (P&R), efficient resource allocation, and support for different quality of service (QoS) requirements. In this paper, we propose a novel stateful PCE-cloud (SPC) based architecture of GMPLS optical networks for cloud services. The cloud computing technologies (e.g. virtualization and parallel computing) are applied to the construction of SPC for improving the reliability and maximizing resource utilization. The functions of SPC and GMPLS based control plane are expanded according to the features of cloud services for different QoS requirements. The architecture and detailed description of the components of SPC are provided. Different potential cooperation relationships between public stateful PCE cloud (PSPC) and region stateful PCE cloud (RSPC) are investigated. Moreover, we present the policy-enabled and constraint-based routing scheme base on the cooperation of PSPC and RSPC. Simulation results for verifying the performance of routing and control plane reliability are analyzed.
  • COMMUNICATIONS SYSTEM DESIGN
    Cooperative Interference Game in Cognitive Radio Hidden Terminal Scenario
    Zhang Yifan, Guo Chunxia, Li Wei
    2015, 1(10): 128-135.
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    Hidden terminal problem in spectrum sensing is one of the most challenging problems in cognitive radio network (CRN). To tackle this problem, we propose a novel Cooperative Interference Game scheme in this paper. The scheme adopted full duplex (FD) mode to sense over multiple sub-bands in an iterative manner without extra sensing devices. The implementation algorithm of the proposed scheme is consisted of three modules: the formulation of the maximum transmit power limitation of second user (SU); the self-interference cancellation coefficient; and the optimal location of SU for an optimized low collision probability. Monte Carlo simulation proved that compared with cooperative spectrum sensing, the proposed scheme significantly improves the performance of spectrum detection and mitigates hidden terminal problem to a large extent with less energy consumption.
    • NETWORK TECHNOLOGY AND APPLICATION
  • NETWORK TECHNOLOGY AND APPLICATION
    Achieving Consistence for Cross-Domain WAN Control in Software-Defined Networks
    ZHOU Boyang, WU Chunming1, GAO Wen1, HONG Xiaoyan2, JIANG Ming3, CHEN Shuangxi4
    2015, 1(10): 136-146.
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    When applying Software-Defined Networks (SDN) to WANs, the SDN flexibility enables the cross-domain control to achieve a better control scalability. However, the control consistence is required by all the cross-domain services, to ensure the data plane configured in consensus for different domains. Such consistence process is complicated by potential failure and errors of WANs. In this paper, we propose a consistence layer to actively and passively snapshot the cross-domain control states, to reduce the complexities of service realizations. We implement the layer and evaluate performance in the PlanetLab testbed for the WAN emulation. The testbed conditions are extremely enlarged comparing to the real network. The results show its scalability, reliability and responsiveness in dealing with the control dynamics. In the normalized results, the active and passive snapshots are executed with the mean times of 1.873s and 105ms in 135 controllers, indicating its readiness to be used in the real network.
  • NETWORK TECHNOLOGY AND APPLICATION
    Modeling and Generating Realistic Background Traffic by Hybrid Approach
    Qian Yaguan, Guan Xiaohui, Jiang Ming, Cen Gang
    2015, 1(10): 147-157.
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    One of the key challenges in large-scale network simulation is the huge computation demand in fine-grained traffic simulation. Apart from using high-performance computing facilities and parallelism techniques, an alternative is to replace the background traffic by simplified abstract models such as fluid flows. This paper suggests a hybrid modeling approach for background traffic, which combines ON/OFF model with TCP activities. The ON/OFF model is to characterize the application activities, and the ordinary differential equations (ODEs) based on fluid flows is to describe the TCP congestion avoidance functionality. The apparent merits of this approach are (1) to accurately capture the traffic self-similarity at source level, (2) properly reflect the network dynamics, and (3) efficiently decrease the computational complexity. The experimental results show that the approach perfectly makes a proper trade-off between accuracy and complexity in background traffic simulation.
    • SECURITY SCHEMES AND SOLUTIONS
  • SECURITY SCHEMES AND SOLUTIONS
    Internet-Oriented Optimization Schemes for Joint Compression and Encryption
    Wang Yilei, Chang Xiaotao, Amit Golander, Hubertus Franke, Chen Beijing
    2015, 1(10): 158-168.
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    Compression and encryption are widely used in network traffic in order to improve efficiency and security of some systems. We propose a scheme to concatenate both functions and run them in a paralle pipelined fashion, demonstrating both a hardware and a software implementation. With minor modifications to the hardware accelerators, latency can be reduced to half. Furthermore, we also propose a seminal and more efficient scheme, where we integrate the technology of encryption into the compression algorithm. Our new integrated optimization scheme reaches an increase of 1.6X by using parallel software scheme However, the security level of our new scheme is not desirable compare with previous ones. Fortunately, we prove that this does not affect the application of our schemes.
    • ICT MANAGEMENT
  • ICT MANAGEMENT
    Data Mapping Principles and Algorithm for Self-Configurable Systems
    LI Fuliang, AN Changqing, YANG Jiahai, WU Jianping, WANG Xingwei, XU Linchuan, XU Xin
    2015, 1(10): 169-181.
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    With the challenges brought by the expansion of network scale, as well as the diversity of the equipments and the complexity of network protocols, many self-configurable systems have been proposed combining formal specification and model finding techniques. In this paper, we pay more attention to formal specifications of network information, i.e., exploring principles and algorithm to map network information (topology, devices and status, etc.) to Alloy specifications. We first model network information in relational form, which is easy to realize because of the structured feature of network information in nature. Then we map the relational data to Alloy specifications according to our novel data mapping principles and algorithm. Based on the transition of relational data, it is possible to automatically map network information to Alloy specifications. We evaluate our data mapping principles and algorithm by applying them to a practical application scenario. The results illustrate that we can find a model for the task within a tolerant time interval, which implies that our novel approach can convert relational data to Alloy specifications correctly and efficiently.
    • PROTOCOLS AND ALGORITHMS
  • PROTOCOLS AND ALGORITHMS
    An Enhanced Spectrum Resource Allocation Algorithm in Hetnets
    Zhao Linjing, Zhao Huaying, Huo Guangrui
    2015, 1(10): 182-192.
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    Efficient spectrum resource allocation in wireless heterogeneous networks is important for improving the system throughput and guaranteeing the user's Quality-of-Service (QoS). In this paper, we propose an enhanced algorithm for spectrum resource allocation in heterogeneous networks. First, the bandwidth of each user is determined by the user's rate demand and the channel state. Second, graph theory is enhanced and used to improve the spectrum efficiency. Third, spectrum resource is dynamically split between macrocell and femtocells with the changes of users' conditions. Our simulation results show that the proposed algorithm improves the system throughput significantly and also guarantees the fairness for the users.
  • PROTOCOLS AND ALGORITHMS
    TDOA Localization Algorithm with Compensation of Clock Offset for Wireless Sensor Networks
    XIONG Hui, CHEN Zhiyuan, YANG Beiya, NI Rongpei
    2015, 1(10): 193-201.
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    This paper presents a source localization algorithm based on the source signal’s time-difference-of-arrival (TDOA) for asynchronous wireless sensor network. To obtain synchronization among anchors, all anchors broadcast signals periodically, the clock offsets and skews of anchor pairs can be estimated using broadcasting signal’s time-of-arrivals (TOA) at anchors. A kalman filter is adopted to improve the accuracy of clock offsets and track the clock drifts due to random fluctuations. Once the source transmits signal, the TOAs at anchors are stamped respectively and source’s TDOA error due to clock offset and skew of anchor pair can be mitigated by a compensation operation. Based on a Gaussian noise model, maximum likelihood estimation (MLE) for the source position is obtained. Performance issues are addressed by evaluating the Cramér-Rao lower bound and the selection of broadcasting period. The proposed algorithm is simple and effective, which has close performance with synchronous TDOA algorithm.