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    Guest Editorial
  • Guest Editorial
    Green Circuit Design for Battery-Free Sensors in Cloud Radio Access Network
    Zeng Tengchan, Ma Zhen, Wang Gongpu, Zhong Zhangdui
    2015, 1(11): 1-11.
    Abstract ( )   Knowledge map   Save
    Cloud radio access network (C-RAN) is considered as a promising approach to solve the bandwidth crunch problem for future wireless network. Another important element for future network is sensors that can monitor physical or environmental conditions. Currently, most sensors need batteries for power, which is energy-consuming and maintenance-heavy. To further improve energy efficiency (EE) of sensors in C-RAN, this paper proposes a new structure as well as practical circuit design for green sensors in C-RAN. The structure can enable sensors to harvest energy from radio signals transmitted by neighbor remote radio heads (RRHs) and user terminals (UTs). To demonstrate the validity of the new structure, a practical circuit design is suggested and the corresponding hardware platform is realized. Specifically, selection criteria for electrical component parameters and design of an impedance-matching network are discussed in details. In addition, two methods to stabilize the output voltage are proposed and analyzed. Finally, simulation results as well as experimental results are provided to corroborate our proposed studies.
  • Guest Editorial
    Performance Analysis in Cloud Radio Access Networks: User-Centralized Coordination Approach
    Munzali Ahmed Abana, Sun Yaohua, Manzoor Ahmed, Lukman A. Olawoyin, Li Yong
    2015, 1(11): 12-23.
    Abstract ( )   Knowledge map   Save
    The cloud radio access network (C-RAN) has recently been proposed as an important component of the next generation wireless networks providing opportunities for improving both spectral and energy efficiencies. The performance of this network structure is however constrained by severe inter-cell interference due to the limited capacity of fronthaul between the radio remote heads (RRH) and the base band unit (BBU) pool. To achieve performance improvement taking full advantage of centralized processing capabilities of C-RANs, a set of RRHs can jointly transmit data to the same UE for improved spectral efficiency. In this paper, a user centralized joint coordinated transmission (UC-JCT) scheme is put forth to investigate the downlink performance of C-RANs. The most important benefit the proposed strategy is the ability to translate what would have been the most dominant interfering sources to usable signal leading to a significantly improved performance. Stochastic geometry is utilized to model the randomness of RRH location and provides a reliable performance analysis. We derive an analytical expression for the closed integral form of the coverage probability of a typical UE. Simulation results confirm the accuracy of our analysis and demonstrate that significant performance gain can be achieved from the proposed coordination schemes.
  • Guest Editorial
    Performance for Device-to-Device Communication with three-time-slot Two-Way Amplify-and-Forward Relay Protocol
    CAI Yan, NI Yiyang, ZHU Hongbo
    2015, 1(11): 24-34.
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    Multi-hop device-to-device (D2D) communication can significantly improve the system performance. This paper studied the outage performance of D2D communication assisted by another D2D user using three-time-slot two-way amplify-and-forward relaying protocol over Rayleigh fading channels. Considering the co-channel interference from cellular user at the D2D node, the approximate expression for the overall outage probability was derived. Furthermore, a power allocation optimum method to minimize the outage probability was developed, and the closed form expression for the optimal power allocation coefficient at the relay was derived. Simulation results demonstrate accuracy of the derived outage probability expressions. Simulation results also demonstrate that the outage performance can be improved using the proposed optimal power allocation method.
  • Guest Editorial
    Channel Estimation for Full-Duplex Relay Transmission in Cloud Radio Access Networks
    Hu Chunjing, Li Jian, Mao Zhendong, Ban Yourong
    2015, 1(11): 35-42.
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    Relay in full-duplex (FD) mode can achieve higher spectrum efficiency than that in half-duplex mode, while it is crucial to suppress relay self-interference to ensure transmission quality which requires instantaneous channel state information (CSI). In this paper, the channel estimation issue in FD amplify-and-forward relay networks is considered, where the training-based estimation technique is adopted. Firstly, the least square (LS) estimation is implemented to obtain composite channel coefficients of source-relay-destination (SRD) channel and relay loop-interference (LI) channel in order to assist destination in performing data detection. Secondly, both LS and maximum likelihood estimation methods are utilized to perform individual channel estimation aiming at supporting successive interference cancelation at destination. Finally, simulation results demonstrate the effectiveness of both composite and individual channel estimation, and the presented ML method can achieve lower MSEs than LS solution.
  • Guest Editorial
    Self-healing Based on Cooperative Transmission via Bender’s Decomposition in Cloud Radio Access Network
    Yin Mengjun, Li Wenjing, Yu Peng, Feng Lei, Qiu Xuesong
    2015, 1(11): 43-52.
    Abstract ( )   Knowledge map   Save
    To employ the network resources more effectively and flexibly, cloud radio access network (C-RAN) adopts centralized network construction and management. Since the new network characteristics, the self-healing is reliable distinguish compared with previous studies. This paper drives a solution for self-healing based on cooperative transmission and power adjustment under C-RAN self-healing management architecture. This compensation model with the aim to maximize the number of connected UEs and optimize power regulation is solved by Benders’ decomposition algorithm. And through the simulation, this paper verifies the speediness and effectiveness of this scheme.
  • Guest Editorial
    Analysis and Field Trial Results on C-plane and U-plane Split Scheme in Virtual Sectorization System
    XIE Weiliang, WU Zhouyun, YANG Fengyi, YANG Tao
    2015, 1(11): 53-61.
    Abstract ( )   Knowledge map   Save
    Capacity enhancement approaches are being intensively studied in the past few years to address the soaring capacity demands. The network densification technology is recognized as one promising solution. However, the ultra-dense network scheme suffers from severe interference and frequent handovers, which degrade the system performance significantly. In this paper, a virtual sectorization system leveraging a C-plane (control signaling plane) and U-plane (user data plane) split scheme is proposed to overcome these two fundamental problems. Besides, a well-designed field trial is conducted to evaluate its performance. The results show that the interference can be avoided, which leads to a tremendous increase in system capacity. In addition, the number of handovers is also greatly decreased. Thus, the trial results verify the huge potential of the C-plane and U-plane split scheme for system capacity and user experience enhancements.
    • REVIEW PAPER
  • REVIEW PAPER
    Review of Coded Modulation Free Space Optical Communication System
    Wang Kaimin, Liu Bo, Zhang Lijia, Zhang Qi, Tian Qinghua, Xin Xiangjun
    2015, 1(11): 62-78.
    Abstract ( )   Knowledge map   Save
    This paper presents a constructive discussion and inclusive review on advancements in the coded modulation free-space optical (FSO) communication system and corresponding techniques. These techniques mainly include channel model, forward error correction (FEC) and modulation schemes. Firstly, a complete view of FSO system is presented which contains the description, the current research situation along with the advantages over the traditional radio frequency (RF) wireless communication and fiber optical communications. Then, the channel model, FEC, modulation schemes and complete system of coded modulation FSO are analyzed successively. At last, the review work of coded modulation FSO system is summarized and further improvements are prospected.
    • COMMUNICATIONS SYSTEM DESIGN
  • COMMUNICATIONS SYSTEM DESIGN
    Distributed Resource Allocation in Ultra-Dense Networks via Belief Propagation
    CHEN Siyi, XING Chengwen, FEI Zesong
    2015, 1(11): 79-91.
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    Ultra-dense networking is widely accepted as a promising enabling technology to realize high power and spectrum efficient communications in future 5G communication systems. Although joint resource allocation schemes promise huge performance improvement at the cost of cooperation among base stations, the large numbers of user equipment and base station make jointly optimizing the available resource very challenging and even prohibitive. How to decompose the resource allocation problem is a critical issue. In this paper, we exploit factor graphs to design a distributed resource allocation algorithm for ultra dense networks, which consists of power allocation, subcarrier allocation and cell association. The proposed factor graph based distributed algorithm can decompose the joint optimization problem of resource allocation into a series of low complexity subproblems with much lower dimensionality, and the original op-timization problem can be efficiently solved via solving these subproblems iteratively. In addition, based on the proposed algorithm the amounts of exchanging information overhead between the resulting subprob-lems are also reduced. The proposed distributed algorithm can be understood as solving largely dimensional optimization problem in a soft manner, which is much preferred in practical scenarios. Finally, the performance of the proposed low complexity distributed algorithm is evaluated by several numerical results.
  • COMMUNICATIONS SYSTEM DESIGN
    A k-coverage scheduling scheme in wireless sensor network based on hard-core process in Rayleigh fading channel
    Kang Lin, Li Xiuhua, Zhang Yinghai, Wang Weidong, Li Jinlan
    2015, 1(11): 92-103.
    Abstract ( )   Knowledge map   Save
    Sensing coverage is a fundamental design issue in wireless sensor networks (WSNs), while sensor scheduling ensures coverage degree to the monitored event and extends the network lifetime.In this paper, we address k-coverage scheduling problem in dense WSNs, we maintain a connected k-coverage energy efficiently through a novel Hard-Core based Coordinated Scheduling (HCCS), in which hard-core is a thinning process in stochastic geometry that inhibits more than one active sensor covering any area redundantly in a minimum distance. As compared with existing coordinated scheduling, HCCS allows coordination between sensors with little communication overhead. Moreover, due to the traditional sensing models in k-coverage analysis is unsuitable to describe the characteristic of transmit channel in dense WSNs, we propose a novel sensing model integrating Rayleigh Fading and Distribution of Active sensors (RFDA), and derive the coverage measure and k-coverage probability for the monitored event under RFDA. In addition, we analyze the influence factors, i.e. the transmit condition and monitoring degree to the k-coverage probability. Finally, through Monte Carlo simulations, it is shown that the k-coverage probability of HCCS outperforms that of its random scheduling counterpart.
  • COMMUNICATIONS SYSTEM DESIGN
    Partial Iterative Decode of Turbo Codes for On-board Processing Satellite Platform
    LI Hang, GAO Zhen, ZHAO Ming, WANG Jing
    2015, 1(11): 104-111.
    Abstract ( )   Knowledge map   Save
    There is a contradiction between high processing complexity and limited processing resources when turbo codes are used on the on-board processing (OBP) satellite platform. To solve this problem, this paper proposes a partial iterative decode method for on-board application, in which satellite only carries out limited number of iteration according to the on-board processing resource limitation and the throughput capacity requirements. In this method, the soft information of parity bits, which is not obtained individually in conventional turbo decoder, is encoded and forwarded along with those of information bits. To save downlink transmit power, the soft information is limited and normalized before forwarding. The iteration number and limiter parameters are optimized with the help of EXIT chart and numerical analysis, respectively. Simulation results show that the proposed method can effectively decrease the complexity of on-board processing while achieve most of the decoding gain..
    • NETWORK TEChNOLOGY AND APPLICATION
  • NETWORK TEChNOLOGY AND APPLICATION
    Impact of Optical Hop Constraints on the IP/MPLS-over-WSON Networks CAPEX
    Liu Fengqing, Jaume Comellas
    2015, 1(11): 112-118.
    Abstract ( )   Knowledge map   Save
    In this work, the impact of hop constraints on the CAPEX of multi-layer IP/MPLS over WSON networks is evaluated under different scenarios. By routing lightpaths with different number of transparent hops, the cost of networks varies significantly. This effect is thoroughly analyzed with a heuristic algorithm for different network topologies belonging to some European network operators. The main conclusion extracted is that limiting the transparent reach in such multi-layer networks can give a good tradeoff between CAPEX of IP/MPLS networks and WSON networks, and even lead to significant savings in CAPEX when compared to longer lightpaths routing strategies.
  • NETWORK TEChNOLOGY AND APPLICATION
    User-Oriented Hybrid Opportunistic Network Design
    Zhang Yong, Li Jin, Song Mei, Yang Ming
    2015, 1(11): 119-133.
    Abstract ( )   Knowledge map   Save
    To improve the end-to-end Successful Delivery Probability (SDP) of mobile nodes in opportunistic network, hybrid Opportunistic Network (OppNet) architecture using Fix Infrastructure Nodes (FINs) is proposed. As enhanced OppNet serving for special users, the network planning and design should take user's mobility behavior into account. We adopt collected users' mobility records, analyze users' stay pattern, and establish Message Exchange Points (MEPs) where FINs should be installed. Our solution includes MEPs detection algorithm, Maximum end-to-end Success Delivery Probability (MSDP) detection algorithm, and simulated annealing algorithm. After data preprocessing, MEPs detection algorithm detects feasible locations from users' trajectory records where not more than one user visit frequently. End to end SDPs of these feasible MEPs are evaluated using MSDP detection algorithm. To reduce the computation complexity, a simulated annealing algorithm to select optimal FIN locations in a large number of feasible MEPs is given. The evaluation experiments based on real-life trajectory dataset verify our proposal can achieve better E2E SDP gain than "most visitors" strategy and "max residence probability" strategy.
  • NETWORK TEChNOLOGY AND APPLICATION
    Semi-automatic Remote Medicine Monitoring System of Mobile Users
    Du Zhanwei, Yang Yongjian
    2015, 1(11): 134-142.
    Abstract ( )   Knowledge map   Save
    The advances in biological sensors have resulted in rapid development of various remote medical care systems, which enable extended independent living at home and improvement of quality of life for individuals. Now, it is possible for us to monitor not only people’s physical health but also mental health. Considering the incomplete utilization of mental sensors and electronic health record in most Remote medical care systems, we propose a remote medical care system to monitor people’s physical and mental health, with the help of ontology model for with Electronic health record knowledge. In this study, the system architecture will be presented first. Then health solutions about the EHR and emotion (the ontology model of EHR and the emotion detection method) are shown. And finally, some preliminary tests are given out to show this system’s practicability and novelty.
    • ECURITY SCHEMES AND SOLUTIONS
  • ECURITY SCHEMES AND SOLUTIONS
    Finding the Hidden Hands: A Case Study of Detecting Organized Posters and Promoters in SINA Weibo
    Wang Xiang, Zhang Zhilin, Yu Xiang, Jia Yan, Zhou Bin, Li Shasha
    2015, 1(11): 143-155.
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    With the development of online social networks, a special group of online users named organized posters (or Internet water army, Internet paid posters in some literatures) have flooded the social network communities. They are organized in groups to post with specific purposes and sometimes even confuse or mislead normal users. In this paper, we study the individual and group characteristics of organized posters. A classifier is constructed based on the individual and group characteristics to detect them. Extensive experimental results on three real datasets demonstrate that our method based on individual and group characteristics using SVM model (IGCSVM) is effective in detecting organized posters and better than existing methods. We take a first look at finding the promoters based on the detected organized posters of our IGCSVM method. Our experiments show that it is effective in detecting promoters.
  • ECURITY SCHEMES AND SOLUTIONS
    Properties of GSW and Their Applications
    Yang Xiaoyuan, Zhou Tanping, Zhang Wei, Tan Zhenlin
    2015, 1(11): 156-163.
    Abstract ( )   Knowledge map   Save
    In CRYPTO’13, Gentry et al. proposed a fully homomorphic encryption scheme, called GSW. We find that the scheme has three special properties, which are not sufficiently recognized and applied in current literatures.Property 1: Noise grows asymmetrically in multiplication.Property 2: Small noise in MultConst(C,a).Property 3: Fixed noise bound when α is a power of 2 in MultConst(C,a).We made use of property 1 to the Yi’s private searching on streaming data protocol, called YBVX. Compared with YBVX, the four mainly aspects of efficiency in our protocol had been improved, the computation complexity of the sever decreased from O(ml2 +μ)multi.+O(ml2 +μ)add.+O(μd)enc.+O(μ)ADD.to O(m +μ)mulit.+O(m +μ)add.+O(μd)enc.+O(μ) ADD; the space complexity decreased from O(ml2+μd) to O(m +μd); the communication complexity decreased from O(ml)+O(d|D|k) to O(m) + O(d|D|k); the computation complexity of the client decreased from O(ml)dec.+O(d|D|)enc to O(m)dec.+O(d|D|)enc. what’s more, the above three properties can have a variety of applications, ranging from improving the property of cryptographic prototypes to protocol building.
    • STRATEGIES AND SCHEMES
  • STRATEGIES AND SCHEMES
    A Virtual TDOA Localization Scheme of Chinese DTMB Signal in Radio Monitoring Networks
    LIU Shang, RAO Menglou, TAO Yunzheng, LIU Long, ZHANG Ping
    2015, 1(11): 164-176.
    Abstract ( )   Knowledge map   Save
    As the radio communications technology widely used, wireless location technology plays a more important role in maintaining the order of the air waves. However concretely effective symbol calibration method with regard to Chinese DTMB signal of different frame mode is quite under research due to the multiple structure of DTMB signal. In this paper, we propose a Time Difference of Arrival(TDOA)-based passive location scheme using least square principle. Utilizing the large number of anchor nodes in wireless monitoring network, a novel algorithm is formulated to solve the None-Line-Of-Sight problem. The derived Cramer Rao Lower Bound of the localization method guides to the accuracy of the position outcome with regards to the calibration precision. In contrast with traditional multi-terminal location schemes, our location scheme can reduce calculation complexity and location costs abruptly. A two-step NLOS identification algorithm is proposed. Computer simulation is employed to verify the well performance of the calibration method of 3-4 dB superiority than normal method and also the whole localization scheme for less than 50 meters through channel of SNR lower than dB. Simulation also shows that our algorithm can effectively identify NLOS path and improve positioning accuracy.
  • STRATEGIES AND SCHEMES
    WoT/SDN : Web of Things Architecture Using SDN
    Qiu Xiaofeng, Liu Wenmao, Gao Teng, He Xinxin, Wen Xutao, Chen Pengcheng
    2015, 1(11): 177-187.
    Abstract ( )   Knowledge map   Save
    WoT (Web of Things) integrates smart devices into Web by reusing and extending Web standards. While Web technology makes the developers’ job easier, it faces security, management and efficiency challenges. We propose WoT/SDN, the architecture of resource oriented WoT built on SDN (Software Defined Network), in which applications could be developed through resource subscription and Mashup with the programmability provided by SDN. The key components are designed, including Security and Management Controller (SMC), various atomic services and resource subscription syntax. Three applications covering device management, data access and security protection are demonstrated. Compared to traditional resource-oriented WoT systems, our test results show that SDN, with its logically centralized control capability and awareness of flow forwarding, provides new opportunity to improve performance, simplify management and enhance security for WoT.
  • STRATEGIES AND SCHEMES
    A scheme for verifying the integrity of outsourced data
    Wang Xiaoming, Yu Fang, Lin Yanchun, Gan Qingqing, Wu Daini
    2015, 1(11): 188-195.
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    Unauthorized tampering with outsourced data can result in significant losses for both data owner and users. Data integrity therefore becomes an important factor in outsourced data systems. In this paper, we address this problem and propose a scheme for verifying the integrity of outsourced data. We first propose a new authenticated data structure for authenticating membership queries in sets based on accumulators, and then show how to apply it to the problem of verifying the integrity of outsourced data. We also prove that our scheme is secure under the q-strong Diffie-Hellman assumption. More importantly, our scheme has the constant cost communication, meanwhile keeping other complexity measures constant. Compared to previous schemes based on accumulators, our scheme reduces update cost and so improves previous schemes based on accumulators. In addition, the experimental comparison shows that our scheme outperforms the previous schemes.
    • ICT MANAGEMENT
  • ICT MANAGEMENT
    Sponge: An Oversubscription Strategy Supporting Performance Interference Management in Cloud
    Liu Ying
    2015, 1(11): 196-209.
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    Resource oversubscription optimizes the utilization of the computing resources. Many well-known virtual machine monitors (VMMs), such as Xen and KVM, adopt this approach to help maximize the yield of the cloud datacenters. That is, with proper resource oversubscription strategies, more virtual machines (VMs) can be supported by limited resources. However, performance interference among VMs hosting in the same physical machines (PMs) exists in cloud environment, and probably aggravated by resource oversubscription strategies, which aims to put more VMs into the same PM. In this paper, we present a resource oversubscription strategy called Sponge targeting cloud platforms. Sponge mitigates the issue of performance interference among the oversubscribed co-hosting VMs. Sponge also provides a VM association strategy for each PM to handle with its best-effort. We performed our evaluation on a virtual datacenter simulated by Xen. Our evaluation results show that Sponge improves the resources utilization and manages to make each VM meet its performance requirement even hosting with other VMs in the same PM.