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    20 June 2013, Volume 29 Issue 6
    Topic: layered heterogeneous wireless networks
    3-Dimensional Dense Coverage: Opportunities and Challenges for Future Mobile Communications
    Wei Chen,Dongming Wang,Jiaheng Wang,Feifei Gao,Muheng Peng
    2013, 29(6):  2-9.  doi:10.3969/j.issn.1000-0801.2013.06.001
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    Within just a few decades, mobile communications have undergone a rapid growth from its initial concept to the worldwide prosperity, and essentially changed people's daily life as well as the way of working and thinking, thereby becoming the most important connection between individuals and information networks. Although almost all the spectrum resources have been devoted to mobile communications, the demand of higher capacity over a unit area is still increasing, due to the trend that the density of mobile users is increasing and the amount of traffics grow explosively. No doubt such an ever-increasing demand cannot be met by simply relying on the improvement of either physical layer transmission techniques or planar cellular infrastructures. As an emerging network architecture aiming to future metropolitan patterns, 3-deminsional dense coverage is expected to provide a novel spectrum reuse methodology, significantly improving the spectrum efficiency of mobile communication systems through spectrum reuse in the third dimension beyond the planar dimensions. Some fundamental problems of 3-deminsional dense coverage oriented mobile communications systems were investigated, the key challenges was pointed out, and possible solutions for 3-deminsional networks from both the physical and logical perspectives were provided.

    Device-to-Device Communication as an Underlay in Coordinated Heterogenous Cellular Network
    Chen Xu,Lingyang Song
    2013, 29(6):  10-16.  doi:10.3969/j.issn.1000-0801.2013.06.002
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    Device-to-device(D2D)communication enables seamless operation of combining cellular and mobile Ad Hoc networks, which significantly improves the system spectrum efficiency and network capacity. The concept and application challenges of D2D local area network in theory and practice were introduced. The importance of cross layer resource management in solving interference avoidance of D2D communication was discussed, and an example of wireless resource management was also provided. The data results show that the performance of the proposed scheme is close to that of the exhaustive search optimal scheme, while has a relatively lower complexity. At present, D2D communication exhibits vast potential of achieving high system capacity and fully exploring wireless resources.

    Key Technologies and Protocol Architectures in Heterogeneous Network
    Hongyan Liu,Chunjing Hu,Yuan Li
    2013, 29(6):  17-24.  doi:10.3969/j.issn.1000-0801.2013.06.003
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    Heterogeneous network (HetNet) is recently becoming one of the key technologies in LTE-Advanced network, because it can significantly improve spectrum efficiency and system capacity, while meeting different requirements for coverage in hotspots. The research background, term definitions and system architecture of HetNet were detailed. Furthermore, the interference problem caused by the variation in network topology, and the schemes for enhanced inter cell interference coordination (eICIC) in the 3rd generation partnership project (3GPP) standardization were focused on. Lastly, other key technologies in HetNet were also analyzed, such as self-organized network (SON), backhaul link design, mobility management, energy saving and cognitive radio, etc. Resolutions of those aforementioned key technologies have profound guiding significance for the commercial deployment of HetNet.

    Research on Key Technologies of Heterogeneous Wireless Network Resource Management Based on Centralized Radio Access Network Architecture
    Lin Tian,Guowei Zhai,Liang Huang,Yiqing Zhou,Jinglin Shi
    2013, 29(6):  25-31.  doi:10.3969/j.issn.1000-0801.2013.06.004
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    The future broadband wireless communication network will be a heterogeneous network with multiple access technologies seamlessly integrated. In such heterogeneous network, the key issues are how to share resources such as frequency, software, hardware and so on among different types of networks to reduce cost as well as to provide better services to users. Therefore, a heterogeneous network resource convergence platform was proposed based on the centralized radio access network architecture. This platform provides a feasible solution to support resource cooperation among different networks. Moreover, the key technologies were illustrated in detail, such as resource virtualization, processing resource allocation, dynamic frequency share, network coverage optimization, system performance analysis, etc.

    Research on Radio Resource Management for Hierarchical Heterogeneous Wireless Network
    Feng Tian,Hantao Liu,Liang Zhou
    2013, 29(6):  32-38.  doi:10.3969/j.issn.1000-0801.2013.06.005
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    With the development of communication technology, the hierarchical heterogeneous characters of coverage in networks become more and more clear, which is caused by the need of high quality for wireless applications to users. By the exploration of the radio resource management for heterogeneous hierarchical wireless network, the key techniques were demonstrated which could significantly improve the transmission rate and reduce the energy cost.

    Precoding Based Interference Suppression for Heterogeneous Multi-Tiered Network
    Pinyi Ren,Qinghe Du,Pinyi Sun,Datong Xu
    2013, 29(6):  39-45.  doi:10.3969/j.issn.1000-0801.2013.06.006
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    The coexistence of conventional marcro cells and lowpower small cells form the heterogeneous multi-tiered networks, which can significantly improve the capacity of wireless communications systems. However, the interferences between the marco cells and small cells due to sharing the same frequency band severely degrade the quality of communications and prevent the system capacity from being further enhanced. With the wide application of multiple-input-multiple-output(MIMO)for the 4th generation(4G)mobile communications systems, the interference suppression techniques using MIMO precoding and spatially fading properties have become an attracting and popular research area. The recent progress in the areas of MIMO precoding based interference suppression was introduced. Using the two tier downlink networks as the typical example scenario, the heterogeneous interference model was analyzed and that the key task for interference suppression which pointed out was to jointly design the precoding matrices at transmitters and the processing matrices at receivers and to solve for them in a successive order. Following this principle, several recently emerged MIMO-precoding schemes were further introduced. Finally, the future research direction for interference suppression over heterogenous multi-tiered networks was discussed.

    Topic: cloud computing and voice services
    System Design for Media Server Based on Cloud Computing Technology and the Application Analysis
    Qing Li,Zhehong Tang,Afang Song,Faguang Wang
    2013, 29(6):  47-52.  doi:10.3969/j.issn.1000-0801.2013.06.007
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    A media resource pool of multi-tenant cloud-based resource scheduling, load balancing implementation techniques and processes were proposed. Cloud media in the IMS service platform application solutions, cloud technology, media resources test situation were introduced, and cloud media business model was presented. In order to promote cloud media server hardware and software for the local manufacturers and related industry chain development provides a new idea.

    Research on the Technology of Cloud Media for the Video Conference System
    Hai Sun,Minrui Shi,Ting Huang
    2013, 29(6):  53-56.  doi:10.3969/j.issn.1000-0801.2013.06.008
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    It is a trend that cloud media will supply media service instead of traditional media server in the network. Cloud media is mainly used to process voice/video/data stream in the communication. Based on the requirements of video conference system and the study of the structure of cloud media used in the video conference filed, the key technology points in the application were discussed.

    Study and Design for Cloud Call Center Architecture
    Zhehong Tang,Qing Li,Shaomin Wang
    2013, 29(6):  57-63.  doi:10.3969/j.issn.1000-0801.2013.06.009
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    A cloud call center architecture was presented and the call center platform cloud technology and business model were studied. The cloud call center application prospect and business trends were also described. A reference of call center platform cloud and technology development was provided for the operator.

    Study on Strategy of IMS Cloud
    Lin Wu,Lei Shen,Zhanyue Xi
    2013, 29(6):  64-68.  doi:10.3969/j.issn.1000-0801.2013.06.010
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    The cloud computing is surging and its applications have penetrated in all sectors, including the telecommunications industry. As unified core control of the future convergence of fixed and mobile networks, the importance of IMS network is becoming more prominent. The study on IMS cloud has been just started. The driving force of IMS cloud was introduced firstly, then described the IMS cloud from the aspects of concept, position in the layered cloud reference model and deployment model were described, the overall IMS cloud architecture and strategies were proposed, finally the changes it bring to the operators were briefly analyzed.

    A Dynamic Allocation Method on Virtual Resource in Cloud Call Center
    Ying Ling,Wei Xu
    2013, 29(6):  69-71.  doi:10.3969/j.issn.1000-0801.2013.06.011
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    Business platform built on cloud computing cloud resource pool call center system, can not only do load balancing control at the operational level, realize intelligent call center scheduling and resource allocation, automatically do the equalization processing of incoming load and the agent check-in load, support word service, unified scheduling of service resources and unified operation and management of business, but also need to achieve dynamic resource allocation stretching because the cloud call center business systems deployed in the cloud data center resources pool can be shared with other applications infrastructure. A cloud call center system for dynamic virtualized resources allocation method was presented, which determines the operation of the system resource pool dynamically allocates resources based on the upper application resource pool. The method contains virtual resource dynamic allocation request trigger mechanism initiated by the cloud call center system, the interfaces of cloud call center system and resource management platform for dynamic allocation of resources and so on.

    research and development
    SLA Audit Mechanism of Virtual Machine Memory on Cloud
    Panpan Li,Hongli Zhang,Huimin Deng,Zhigang Zhou
    2013, 29(6):  72-81.  doi:10.3969/j.issn.1000-0801.2013.06.012
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    Cloud service style has shield physical hardware view to cloud tenant, thus untrusted CSP(cloud service provider)may replace expensive physical memory by cheaper hard disk resource, which violates the SLA. Therefore, in order to audit memory SLA of cloud, a novel scheme for auditing physical memory of VM was proposed. This scheme is based on light-weight memory measurement SLA auditing by Xen layer to physical layer. Meanwhile, trust boot mechanism and HyperSentry module to ensure trust boot and integrity guarantee at running time were introduced. Then, digital signatures-based Diffie-Hellman key exchange protocol was also proposed to support strategy security exchange and trust alarm. The experimental results indicate that the proposed module can effectively audit VM memory SLA,and also support strong expansibility of cloud tenant customize strategy with low overhead.

    Study on Minimum Contention Window Size Adjustment Algorithm Based on Neighbor Nodes Number Estimation in Vehicular Ad Hoc Network
    Dapeng Li,Tao Yuan,Haitao Zhao
    2013, 29(6):  82-88.  doi:10.3969/j.issn.1000-0801.2013.06.013
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    In order to solve the periodic broadcast scalability of IEEE 802.11p-based VANET on control channel, a minimum contention window adjustment algorithm based on neighbor nodes number estimation was proposed. First of all, in order to minimize the collision probability, the relationship between minimum contention window(CWmin)and active node number n was deduced on the basis of Markov model IEEE 802.11 broadcast backoff. Then minimum contention window was adjusted dynamically by estimating the number of neighbor nodes in real time. Finally, the proposed algorithm and the original's fixed CWmin method were compared by simulation, and the results show that the proposed algorithm is superior to the original method in broadcast reception rate.

    A Secure Image Transmission Scheme Based on Improved DCSK
    Lifang He,Gang Zhang,Tianqi Zhang
    2013, 29(6):  94-99.  doi:10.3969/j.issn.1000-0801.2013.06.014
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    Non-coherent demodulation technology is applied in the differential chaos shift keying(DCSK)and it's unnecessary for the receiver to generate chaotic synchronous signals at the receiving end. The structure in DCSK is simple and has good performance in anti-noise. However, it is lack of performance in security, and easier to be cracked. A modified DCSK scheme was proposed for the security problems caused by the traditional DCSK scheme. It retains the good performance of the old one and greatly increases security performance at the same time. The theoretical analysis toward the system was deeply carried out. The relationship among the BER, the frequency spread factor and SNR were also deeply analyzed. Finally, it was applied in an image transmission system as an example. The simulation results indicate that the performance of the bit error ratio(BER)and security are greatly improved. The feasibility was also proved by simulations.

    Research on Design of Extending Orthogonal Space-Time Block Code
    Adan Ding,Fei Long,Zhuoyue Li
    2013, 29(6):  100-104.  doi:10.3969/j.issn.1000-0801.2013.06.016
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    For the problem that complex orthogonal design of space-time coding cannot reach full speed and full diversity when the transmitting antenna number is greater than two, two kinds of improved schemes for the closed loop EOSTBC were proposed, which used the orthogonality of the equivalent channel matrix and the feedback of the channel information in the STBC system. The system was designed to maximize the equivalent channel gain. The first scheme was combined with antenna selection techniques and the second was combined with adaptive power allocation. Also, the feedback information was carried respectively. Then its performance was theoretically analyzed and compared. The simulation results show that the bit error rate of the system is reduced and the signal-to-noise ratio gain of the system is improved by the two kinds of improved scheme, and compared with the scheme which is combined with antenna selection technology, the performance of the second scheme combined with adaptive power allocation is superior.

    AODV-ECA: Energy-Efficient AODV Routing Protocol Using Cellular Automata in Wireless Sensor Network
    Qin Yu,Zhihui Xiao,Ning An
    2013, 29(6):  105-109.  doi:10.3969/j.issn.1000-0801.2013.06.017
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    Since the battery equipped wireless sensors have limited energy supply, conserving energy to extend the lifetime becomes the most important requirement in the wireless sensor network(WSN). An AODV routing protocol, AODV-ECA, was proposed, based on cellular automata(CA)mechanism, which was sourced from the thoughts of automatic breeding in biology. AODV-ECA could reduce and balance energy consumption to prolong the network lifetime by means of switching nodes' states between sleeping and working. Finally, AODV-ECA to other energy-efficient routing protocols by NS2 simulator was simulated and evaluated.

    Improvement and Implementation of DRX in TD-LTE System
    Qin Zhu,Xiaowen Li
    2013, 29(6):  110-114.  doi:10.3969/j.issn.1000-0801.2013.06.018
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    With the enriching of mobile terminal business as well as the popularization of intelligent terminal, battery capacity of mobile terminal not only attracts so much attention in the field,but also encounters severe challenges. In the protocol of LTE system, in order to get the further more variety of business support and large amounts of data transmission, the DRX mechanism was taken as an important method to be introduced. Not only the different principles and mechanisms of DRX in different states including idle state and connection state were described in detail, but also the implementation process and the corresponding algorithm were proposed, Based on these, the algorithm of DRX in the connection state was optimized, which avoided invalid configuration resulting in the problem of increased signaling cost. Finally, complete implementation of the mechanism of DRX in different mobile business was given according to the different business characteristic, so that it improves the terminal consumption and signaling cost performance.

    Real-Time Resource Allocation Algorithm for the Quasi-Two-Dimensional Mobile Delay/Disrupt Tolerant Networking
    Ying Wang,Yonghui Zhang
    2013, 29(6):  115-120.  doi:10.3969/j.issn.1000-0801.2013.06.019
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    Resource allocation is one of the core techniques in multi-homing delay/disrupt tolerant networking(DTN), which decides the efficiency of DTN routing, and even affects the whole system. However, schemes based on neural network and genetic algorithms are of computational complexity that is not applied to real-time applications. Therefore the information matrix of access routers and quasi-two-dimensional access bandwidth constraints were designed based on predictable environment of train mobile network, and then an approximation algorithm with O(n) algorithm complexity, based on utility differential, was proposed to meet the real-time applications. Finally simulation showed that call-drop-rate in handover and new call-block-rate only increase by about 1/4, compared with that of the optimized-algorithm, but calculation time decrease down to its 36.99%. It means the algorithm ensures real-time response and could provide good QoS at the same time. The algorithm could be further applied to the real 2-dimensional moving scene.

    Research to Avoid the Energy Hole Problem in the Wireless Sensor Network that Different Data Generation Rate in Different Regional
    Mingsheng Liu,Sen Miao,Yan Li
    2013, 29(6):  121-125.  doi:10.3969/j.issn.1000-0801.2013.06.020
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    The energy hole problem that different data generation rate in different regional in wireless sensor network was studied, using ring network model. Based on this, two kinds of mechanism were defined, which are the data transmitted in the same ring but different area and the data transmitted in the same area but different rings. When the residual energy in an areas was lower than the energy threshold, the area would stop data packet forwarding for other areas, and only send data packet generated by nodes inside. The data packet that generated by other areas would find other areas in the same ring for data packet forwarding. Theory analysis and simulation test display that this strategy could balance energy consumption in network and prolong the network lifetime.

    summarize
    Study of Modern Radio Spectrum Management Mode
    Bo Feng
    2013, 29(6):  132-135.  doi:10.3969/j.issn.1000-0801.2013.06.021
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    Modern radio spectrum management modes were introduced briefly,analyzed and compared.Recommendation on our country's future radio spectrum management was put forward. Spectrum resources management mode should be a dynamic market-based approach, which combines command and control model, property right mode, commons or unlicensed mode and intelligent mode.

    Novel Human-Computer Interaction Technology to Change Mobile Internet
    Jinyuan Liu,Xianzun Meng,Haitao Ding
    2013, 29(6):  136-138.  doi:10.3969/j.issn.1000-0801.2013.06.023
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    Mobile internet, which is changing our life, is developing rapidly, and intelligent terminal is key to the development of all kinds of mobile internet applications. Also, novel human-computer interaction models are not only changing the intelligent terminal, but also changing the future of mobile internet. The interactive models in recent years and key technologies of them were analyzed and the preliminary summary on future trends was concluded as well.

    Operational innovation BBS
    Evolution of Broadband Intelligent Speedup Platform to SDN Architecture
    Yuyong Jia,Bo Yuan,Xiaoying Huang
    2013, 29(6):  139-144.  doi:10.3969/j.issn.1000-0801.2013.06.024
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    SDN is a new network architecture, which achieves the flexible control of network traffic by separating the network device control plane and data forwarding plane. Broadband intelligent speedup platform was put forward by China Telecom which followed PCC/RACF architecture, and it was the core cell of the intelligent pipeline strategy to be in charge of the policy control. The similarities and differences between SDN architecture and broadband intelligent speedup architecture were analyzed, and in view of the shortcomings of the broadband intelligent speedup platform, the feasible evolution of broadband intelligent speedup platform based on SDN was put forward.

    Research and Strategic Analysis of New Generation Telecom IT System Disaster Recovery System
    Dezhi Gong,Yirong Shi
    2013, 29(6):  145-150.  doi:10.3969/j.issn.1000-0801.2013.06.025
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    The latest disaster recovery technology was stated and classification principles into critical business systems was elaborated. Also, the architecture of a new generation of disaster recovery technology program was analyzed by taking one branch of China Telecom as an example.

    Research on Resources Configuration of Access Service
    Jie Yin,Wenjun Shen
    2013, 29(6):  158-163.  doi:10.3969/j.issn.1000-0801.2013.06.026
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    Based on a distinctive classification method for telecom business, the definition and resource configuration process of access service was discussed in details. Then an E-R model for resources and access services was proposed. Also, some opinions of access methods and coverage which are very important in service configuration process were showed.

    End-to-End Call Establishment Delay Optimization
    Cuiling Chen
    2013, 29(6):  164-169.  doi:10.3969/j.issn.1000-0801.2013.06.028
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    From the detailed analysis of the current network signaling, the reason for the call setup delay in the network was researhed. And the call establishment delay shortening solution was also provided.

    Treasury Pattern Analysis and Application Based on Security Control Platform
    Jianchuang Ning,Bin Tan,Yeyu Liang
    2013, 29(6):  170-176.  doi:10.3969/j.issn.1000-0801.2013.06.029
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    In order to reduce illegal operations and customer information disclosure of risk caused by the high privilege account abuse, drawing lessons from the way of the bank vault management in warehouse that must switch consist of two warehouse keepers who jointly conduct the warehouse, high authority for supervision and control was used in many means of checks and balances. Through the investigation and analysis of various application scenarios for Guangxi mobile network operation center treasury management, trigger mode, authorization model and working efficiency optimization of treasury management were analyzed, designed and implemented. And it was successfully implemented and applicated in the systems such as voice switching network, WAP and signaling monitoring in network operation center. The results show the query sensitive data volume decrease significantly, and it can effectively curb the abuse of authority of the customer and reduce the risks of disclosure of sensitive information.

Copyright Information
Authorized by: China Association for Science and Technology
Sponsored by: China Institute of Communications
Posts and Telecom Press Co., Ltd.
Publisher: Beijing Xintong Media Co., Ltd.
Editor-in-Chief: Chen Shanzhi
Editorial Director: Li Caishan
Address: F2, Beiyang Chenguang Building, Shunbatiao No.1 Courtyard, Fengtai District, Beijing, China
Postal Code: 100079
Tel: 010-53879277
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E-mail: dxkx@ptpress.com.cn
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ISSN 1000-0801
CN 11-2103/TN
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