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    COMMUNICATIONS THEORIES & SYSTEMS
  • COMMUNICATIONS THEORIES & SYSTEMS
    Directions of Arrival Optimization Method for Broadband Antenna Array Based on Filter Bank
    Ying Liu, Chi Xie
    2018, 15(11): 1-9.
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    This paper proposes an estimation method of the directions of arrival (DOA) for the broadband signals received by a uniform planar antenna array including the mutual coupling effect. The process modeling of antenna array receiving dynamic signal is obtained accurately via building the array system electromagnetic space-time model, and the mutual coupling effect is included in the synthesis procedure automatically. The broadband signal is divided into several sub-bands, and the complex weight of these sub-bands frequencies is figured out using the least mean square iteration programming. In the proposed method, the mutual coupling effect is compensated at the different frequencies. The calculation results show that the method is suitable for the uniform linear and uniform circular array pattern integration, and it is commendably satisfied with the requirement of engineering design.
  • COMMUNICATIONS THEORIES & SYSTEMS
    A Fairness Resource Allocation Algorithm for Coverage and Capacity Optimization in Wireless Self-Organized Network
    Pan Zhao, Lei Feng, Peng Yu, Wenjing Li, Xuesong Qiu
    2018, 15(11): 10-24.
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    To achieve the higher resource efficiency, Coverage and Capacity Optimization (CCO) as an important role of the network self-healing and self-optimization, has become a focus topic in wireless Self-Organized Network (SON). In this paper, a novel CCO scheme is proposed to maximize utility function of the integrated coverage and capacity. It starts with the analysis on the throughput proportional fairness (PF) algorithm and then proposes the novel Coverage and Capacity Proportional Fairness (CCPF) allocation algorithm along with a proof of the algorithms convergence. This proposed algorithm is applied in a coverage capacity optimization scheme which can guarantee the reasonable network capacity by the coverage range accommodation. Next, we simulate the proposed CCO scheme based on telecom operators’ real network data and compare with three typical resource allocation algorithms: round robin (RR), proportional fairness (PF) and max C/I. In comparison of the PF algorithm, the numerical results show that our algorithm increases the average throughput by 1.54 and 1.96 times with constructed theoretical data and derived real network data respectively.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Coexistence Analysis between 5G System and Fixed-Satellite Service in 3400-3600 MHz
    Haifeng Tan, Yanjie Liu, Zhiyong Feng, Qixun Zhang
    2018, 15(11): 25-32.
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    The 3400-3600 MHz band is one of the most important candidate frequency bands for the rollout of 5G system. However, the coexistence between 5G system and fixed-satellite service (FSS) in this frequency band is one of the most challenging problems for both academic researchers and industry engineers. In this paper, the saturation interference from 5G base stations to the existing FSS above 3600 MHz is analyzed and the coexistence solution is achieved, which can reduce the interference and guarantee the coexistence between 5G system and FSS. Furthermore, the Monte Carlo simulation, laboratory test and field test are carried out to verify the coexistence solution. Results show that an isolation distance of 1-2 km is required to avoid the saturation interference in terms of the adjacent bands scenario. To further reduce the isolation distance to 50 m, additional isolation of 35 dB will be necessary, which can be fulfilled by installing a filter at the input port of LNB from a real implementation perspective.
  • COMMUNICATIONS THEORIES & SYSTEMS
    5G Features from Operation Perspective and Fundamental Performance Validation by Field Trial
    Guangyi Liu, Yuhong Huang, Fei Wang, Jianjun Liu, Qixing Wang
    2018, 15(11): 33-50.
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    The fast deployment and penetration of 4G has cultivated human behaviors on mobile data consumption, leading to explosive growth in mobile traffic and stimulating new requirements on the capabilities of mobile networks. To meet the requirements of mobile networks toward year 2020, the next generation of mobile networks (termed as IMT-2020, or 5G) is designed to support 100 Mbps-1 Gbps user-experienced data rate, 1 ms radio transmission latency, and 1 million connections per square kilometer. Recalling the vision and requirements of 5G targeting for commercial launch in 2020, this article overviews the key features of 5G and compares with those of 4G, and reports the world first field trials conducted to validate the key performance of 5G radio interface in 3.5GHz band. The trial results show that a 1 ms transmission latency and 1 Gbps data rate are achievable.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Polar Coded Iterative Multiuser Detection for Sparse Code Multiple Access System
    Hang Mu, Youhua Tang, Li Li, Zheng Ma, Pingzhi Fan, Weiqiang Xu
    2018, 15(11): 51-61.
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    Polar coded sparse code multiple access (SCMA) system is conceived in this paper. A simple but new iterative multiuser detection framework is proposed, which consists of a message passing algorithm (MPA) based multiuser detector and a soft-input soft-output (SISO) successive cancellation (SC) polar decoder. In particular, the SISO polar decoding process is realized by a specifically designed soft re-encoder, which is concatenated to the original SC decoder. This soft re-encoder is capable of reconstructing the soft information of the entire polar codeword based on previously detected log-likelihood ratios (LLRs) of information bits. Benefiting from the soft re-encoding algorithm, the resultant iterative detection strategy is able to obtain a salient coding gain. Our simulation results demonstrate that significant improvement in error performance is achieved by the proposed polar-coded SCMA in additive white Gaussian noise (AWGN) channels, where the performance of the conventional SISO belief propagation (BP) polar decoder aided SCMA, the turbo coded SCMA and the low-density parity-check (LDPC) coded SCMA are employed as benchmarks.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Multiuser Pre-Coding Aided Quadrature Spatial Modulation for Large-Scale MIMO Channels
    Fatang Chen, Kang Yang, Pingping Xing, Huan Zhang, Yanan Jiang
    2018, 15(11): 62-69.
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    Pre-coding aided quadrature spatial modulation (PQSM) is a promising multiple input multiple output (MIMO) transmission technology. The multiuser (MU) detection in PQSM system is investigated in this paper. Based on the known channel state information, pre-coding matrix is designed to pre-process the in-phase and quadrature signals of quadrature spatial modulation (QSM) to reduce the inter-channel interference. In order to lower the complexity at the receiver brought by the orthogonality of the PQSM system, an orthogonal matching pursuit (OMP) detection algorithm and a reconstructed model are proposed. The analysis and simulation results show that the proposed algorithm can obtain a similar bit error rate (BER) performance as the maximum likelihood (ML) detection algorithm with more than 80% reduction of complexity.
  • COMMUNICATIONS THEORIES & SYSTEMS
    A Novel Training Sequence Applied to DCS-Based Channel Estimation
    Weizhang Xu, Xinle Yu, Yanfei Li, Lu Si, Zhanxin Yang
    2018, 15(11): 70-78.
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    Studies have indicated that the distributed compressed sensing based (DCS-based) channel estimation can decrease the length of the reference signals effectively. In block transmission, a unique word (UW) can be used as a cyclic prefix and reference signal. However, the DCS-based channel estimation requires diversity sequences instead of UW. In this paper, we proposed a novel method that employs a training sequence (TS) whose duration time is slightly longer than the maximum delay spread time. Based on proposed TS, the DCS approach perform perfectly in multipath channel estimation. Meanwhile, a cyclic prefix construct could be formed, which reduces the complexity of the frequency domain equalization (FDE) directly. Simulation results demonstrate that, by using the method of simultaneous orthogonal matching pursuit (SOMP), the required channel overhead has been reduced thanks to the proposed TS.
  • COMMUNICATIONS THEORIES & SYSTEMS
    On the Performance of Wireless-Powered Cooperative DF Relaying Networks with Imperfect CSI
    Shuai Liu, Zujun Liu, Dechun Sun, Hong Yang, Kechu Yi, Kan Wang
    2018, 15(11): 79-92.
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    This paper studies several performance metrics of a wireless-powered decode-and-forward (DF) relay network with imperfect channel state information (CSI). In particular, based on the time switching (TS) protocol, the energy-constrained relay harvesting energy from a power beacon (PB), and uses that harvested energy to forward the source information to destination. The closed-form expression of the outage probability is firstly derived over Rayleigh fading channels. Then, the asymptotic analysis, throughput as well as the symbol error probability (SEP) are derived based on the expression of the outage probability. Next, both transmission power of the source and the power beacon are optimized through the throughput optimization. Finally, simulations are conducted to corroborate our theoretical analysis, and to reveal the impact of the transmission power of the source and PB as well as the imperfect CSI on the system performance.
    • NETWORKS & SECURITY
  • NETWORKS & SECURITY
    An Enhanced Hadoop Heartbeat Mechanism for MapReduce Task Scheduler Using Dynamic Calibration
    Xinzhu Lu, Keatkeong Phang
    2018, 15(11): 93-110.
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    MapReduce is a popular programming model for processing large-scale datasets in a distributed environment and is a fundamental component of current cloud computing and big data applications. In this paper, a heartbeat mechanism for MapReduce Task Scheduler using Dynamic Calibration (HMTS-DC) is proposed to address the unbalanced node computation capacity problem in a heterogeneous MapReduce environment. HMTS-DC uses two mechanisms to dynamically adapt and balance tasks assigned to each compute node: 1) using heartbeat to dynamically estimate the capacity of the compute nodes, and 2) using data locality of replicated data blocks to reduce data transfer between nodes. With the first mechanism, based on the heartbeats received during the early state of the job, the task scheduler can dynamically estimate the computational capacity of each node. Using the second mechanism, unprocessed Tasks local to each compute node are reassigned and reserved to allow nodes with greater capacities to reserve more local tasks than their weaker counterparts. Experimental results show that HMTS-DC performs better than Hadoop and Dynamic Data Placement Strategy (DDP) in a dynamic environment. Furthermore, an enhanced HMTS-DC (EHMTS-DC) is proposed by incorporating historical data. In contrast to the “slow start” property of HMTS-DC, EHMTS-DC relies on the historical computation capacity of the slave machines. The experimental results show that EHMTS-DC outperforms HMTS-DC in a dynamic environment.
  • NETWORKS & SECURITY
    Authorized Identity-Based Public Cloud Storage Auditing Scheme with Hierarchical Structure for Large-Scale User Groups
    Yue Zhang, Hanlin Zhang, Rong Hao, Jia Yu
    2018, 15(11): 111-121.
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    Identity-based public cloud storage auditing schemes can check the integrity of cloud data, and reduce the complicated certificate management. In such a scheme, one Private Key Generator (PKG) is employed to authenticate the identity and generate private keys for all users, and one Third Party Auditor (TPA) is employed to by users to check the integrity of cloud data. This approach is undesirable for large-scale users since the PKG and the TPA might not be able to afford the heavy workload. To solve the problem, we give a hierarchical Private Key Generator structure for large-scale user groups, in which a root PKG delegates lower-level PKGs to generate private keys and authenticate identities. Based on the proposed structure, we propose an authorized identity-based public cloud storage auditing scheme, in which the lowest-level PKGs play the role of TPA, and only the authorized lowest-level PKGs can represent users in their domains to check cloud data’s integrity. Furthermore, we give the formal security analysis and experimental results, which show that our proposed scheme is secure and efficient.
  • NETWORKS & SECURITY
    To Construct High Level Secure Communication System: CTMI Is Not Enough
    Sen Xu, Xiangjun Lu, Aidong Chen, Haifeng Zhang, Haihua Gu, Dawu Gu, Kaiyu Zhang, Zheng Guo, Junrong Liu
    2018, 15(11): 122-137.
    Abstract ( )   Knowledge map   Save
    Public key cryptographic (PKC) algorithms, such as the RSA, elliptic curve digital signature algorithm (ECDSA) etc., are widely used in the secure communication systems, such as OpenSSL, and a variety of information security systems. If designer do not securely implement them, the secret key will be easily extracted by side-channel attacks (SCAs) or combinational SCA thus mitigating the security of the entire communication system. Previous countermeasures of PKC implementations focused on the core part of the algorithms and ignored the modular inversion which is widely used in various PKC schemes. Many researchers believe that instead of straightforward implementation, constant time modular inversion (CTMI) is enough to resist the attack of simple power analysis combined with lattice analysis. However, we find that the CTMI security can be reduced to a hidden t-bit multiplier problem. Based on this feature, we firstly obtain Hamming weight of intermediate data through side-channel leakage. Then, we propose a heuristic algorithm to solve the problem by revealing the secret (partial and full) base of CTMI. Comparing previous necessary input message for masking filtering, our procedure need not any information about the secret base of the inversion. To our knowledge, this is the first time for evaluating the practical security of CTMI and experimental results show the fact that CTMI is not enough for high-level secure communication systems.
  • NETWORKS & SECURITY
    Performance Analysis of Physical Layer Security over α-η-κ-μ Fading Channels
    Shaobo Jia, Jiayan Zhang, Honglin Zhao, Yao Xu
    2018, 15(11): 138-148.
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    In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular, we address the secrecy performance in terms of the average secrecy capacity (ASC) and the secrecy outage probability (SOP), for which novel analytical expressions are derived. Simulation results verify the analysis and demonstrate the impact of the physical parameters on the secrecy performance of this new channel fading model.
  • NETWORKS & SECURITY
    A Greedy Algorithm for Task Offloading in Mobile Edge Computing System
    Feng Wei, Sixuan Chen, Weixia Zou
    2018, 15(11): 149-157.
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    Mobile edge computing (MEC) is a novel technique that can reduce mobiles’ computational burden by tasks offloading, which emerges as a promising paradigm to provide computing capabilities in close proximity to mobile users. In this paper, we will study the scenario where multiple mobiles upload tasks to a MEC server in a sing cell, and allocating the limited server resources and wireless channels between mobiles becomes a challenge. We formulate the optimization problem for the energy saved on mobiles with the tasks being dividable, and utilize a greedy choice to solve the problem. A Select Maximum Saved Energy First (SMSEF) algorithm is proposed to realize the solving process. We examined the saved energy at different number of nodes and channels, and the results show that the proposed scheme can effectively help mobiles to save energy in the MEC system.
  • NETWORKS & SECURITY
    A Key Management Scheme Based on Hypergraph for Fog Computing
    Zhi Li, Yanzhu Liu, Di Liu, Chunyang Li, Wei Cui, Guanglin Hu
    2018, 15(11): 158-170.
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    Fog computing is a new paradigm supporting the stringent requirements of mobility applications by bridging cloud computing and smart devices. Since the smart devices may be deployed in dynamic areas where are out of strict monitoring and protection, fog computing requires security protections to ensure confidentiality and integrity. In this article, to deal with security requirements and considering the distinctive features, a key management based on hypergraph schemed is designed. Firstly, based on the key hypergraph, the three hierarchy architecture of fog computing is divided into two subnetworks. Furthermore, each key management process of both two subnetworks is designed to satisfy the operational and security requirements of fog computing. Finally, the performance evaluation and numerical simulation have been provided to validate the proposed scheme.
  • NETWORKS & SECURITY
    Fast Secret Key Generation Based on Dynamic Private Pilot from Static Wireless Channels
    Yu Huang, Liang Jin, Hongquan Wei, Zhou Zhong, Shengjun Zhang
    2018, 15(11): 171-183.
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    In static or quasi-static wireless channel environments, secret key generation (SKG) based on wireless channels is vulnerable to active attacks due to the openness and invariance of public pilot, especially man-in-the-middle (MITM) attacks, where attacker acts as a transparent relay to manipulate channel measurements and derive the generated keys. In order to fight against this attack, a dynamic private pilot is designed, where both private pilot and secret key are derived from the characteristics of wireless channels and private to third party. In static or quasi-static environments, we use singular value decomposition techniques to reconstitute the wireless channels to improve the randomness of the wireless channels. Private pilot can encrypt and authenticate the wireless channels, which can make channel state information intercepted by MITM attacker reduced to zero and the SKG rate close to that without attacks. Results of analysis and simulation show the proposed SKG scheme can withdraw the MITM attacks.
  • NETWORKS & SECURITY
    Reliable and Load Balance-Aware Multi-Controller Deployment in SDN
    Tao Hu, Peng Yi, Jianhui Zhang, Julong Lan
    2018, 15(11): 184-198.
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    Software Defined Networking (SDN) provides flexible network management by decoupling control plane and data plane. However, such separation introduces the issues regarding the reliability of the control plane and controller load imbalance in the distributed SDN network, which will cause the low network stability and the poor controller performance. This paper proposes Reliable and Load balance-aware Multi-controller Deployment (RLMD) strategy to address the above problems. Firstly, we establish a multiple-controller network model and define the relevant parameters for RLMD. Then, we design the corresponding algorithms to implement this strategy. By weighing node efficiency and path quality, Controller Placement Selection (CPS) algorithm is introduced to explore the reliable deployments of the controllers. On this basis, we design Multiple Domain Partition (MDP) algorithm to allocate switches for controllers according to node attractability and controller load balancing rate, which could realize the reasonable domain planning. Finally, the simulations show that, compared with the typical strategies, RLMD has the better performance in improving the reliability of the control plane and balancing the distribution of the controller loads.
  • NETWORKS & SECURITY
    Toward Energy-Efficiency Optimization of Pktgen-DPDK for Green Network Testbeds
    Guo Li, Dafang Zhang, Yanbiao Li, Keqin Li
    2018, 15(11): 199-207.
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    The packet generator (pktgen) is a fundamental module of the majority of software testers used to benchmark network protocols and functions. The high performance of the pktgen is an important feature of Future Internet Testbeds, and DPDK is a network packet accelerated platform, so we can use DPDK to improve performance. Meanwhile, green computing is advocated for in the future of the internet. Most existing efforts have contributed to improving either performance or accuracy. We, however, shifted the focus to energy-efficiency. We find that high performance comes at the cost of high energy consumption. Therefore, we started from a widely used high performance schema, deeply studying the multi-core platform, especially in terms of parallelism, core allocation, and frequency controlling. On this basis, we proposed an AFfinity-oriented Fine-grained CONtrolling (AFFCON) mechanism in order to improve energy efficiency with desirable performance. As clearly demonstrated through a series of evaluative experiments, our proposal can reduce CPU power consumption by up to 11% while maintaining throughput at the line rate.