Table of Content

25 June 2009, Volume 7 Issue 2

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The whole issue of ZTE Communications June 2009, Vol. 7 No. 2

2009, 7(2):  0. 

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Special Topic

Cognition Based Reconfigurable Wireless Network Technology

Feng Zhiyong, Su Meiyu, Zhang Qixun

2009, 7(2):  1-5. 

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The End-to-End Reconfigurability (E2R ) project aims at realizing the convergence of the heterogeneous radio networks and the optimal utilization of the radio resources. With the continuous development of E2R technology and cognitive theory, the evolution from existing radio networks to future reconfigurable radio networks with the cognitive ability becomes possible. Nowadays the research aspects of E2R include the system architecture of reconfigurable radio networks and some key technologies for their evolution.

Cognitive Engine Technology

Wang Lifeng, Wei Shengqun

2009, 7(2):  6-10. 

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Cognitive Radio (CR ) is an intelligent radio communication system, whose intelligence mostly comes from the Cognitive Engine (CE ). Based on the techniques of software-defined radio and with the support of machine reasoning and learning in artificial intelligence, cognitive engine implements the cognitive loop to realize the abilities of sensing, adaptation and learning in CR. Cognitive engine consists of the modeling system, knowledge base, reasoning engine, learning engine and interfaces. The key techniques are knowledge representation, machine reasoning and machine learning.

Cooperative Spectrum Sensing Techniques in Cognitive Radio

Wang Haijun, Su Xin, Wang Jing

2009, 7(2):  11-15. 

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Cognitive radio has become an effective theory to solve the inefficiency of the spectrum usage. One of the main requirements of cognitive radio systems is the ability to reliably detect the spectrum hole. Previous works on the problem of detection for cognitive radio have suggested the necessity of user cooperation to enable the detection at the low signal-to-noise ratios experienced in practical situations. This paper introduces energy sensing and the cooperative sensing techniques: AND model, OR model, counting model, double threshold model, likelihood ratio model, linear cooperation model and DWCS model. It is proved that significant cooperative gain can be achieved by the proposed models in reducing interference and improving spectrum usage.

Spectrum Occupancy Measurement and Analysis

Tian Fang, Feng Zhiyong, Chen Xing

2009, 7(2):  16-20. 

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This paper analyzes current spectrum utilization from all aspects based on related methods of spectrum measurement. The measurement results show that some spectrum resources are not used effectively due to current fixed spectrum allocation policy, and the spectrum occupancy varies dramatically in terms of time and space. These results provide basis for the development of next generation wireless communication technologies such as Cognitive Radio (CR ).

Key MAC Layer Technologies of Cognitive Radio Network

Zeng Zhimin, Guo Caili

2009, 7(2):  21-26. 

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As a smart spectrum sharing technology, Cognitive Radio (CR ) is becoming a hot topic in the field of wireless telecommunications. Besides providing traditional services, the cognitive radio network Media Access Control (MAC ) layer is required to perform an entirely new set of functions for effective reusing spectrum opportunity, without causing any harmful interference to incumbents. Spectrum sensing management selects and optimizes sensing strategies and parameters by the selection of sensing mode, sensing period, sensing time, sensing channel, and sensing quiet period. Access control avoids collision with primary users mainly by cooperation access and transparent access. Dynamic spectrum allocation optimizes the allocation of uncertain spectrum for binary interference model and accumulative interference model. Security mechanism adds authentication and encryption mechanisms to MAC frame to defense MAC layer security attacks. Cross-layer design combines MAC layer information with physical layer or higher layers information, such as network layer, transmission layer, to achieve global optimization.

Spectrum Resource Management of Cognitive Radio

Liu Qin

2009, 7(2):  27-31. 

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As the most important technology of CR, the wireless spectrum resource management technology is the key to CR performance improvement. By introducing the concept of resource space to describe wireless spectrum resource management in the field of CR technology, a data system of wireless resource management is formed that covers wireless spectrum resource space, resource grid and available resource atlas. Besides, the corresponding lamination distributional management structure and the resource management database are constructed. The resources description system and the management structure will become the theoretical concept foundation and reference of the CR spectrum resources management technology.

Cognition Based Adaptive Control Mechanism

Zhu Jiang, Wang Jun, Li Shaoqian

2009, 7(2):  32-36. 

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According to the basic functions and objectives of Cognitive Radio (CR ) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems. Therefore, the mechanism is described by a cognition loop, which contains the following parts: environment, inner structure of intelligent systems, observation and action.

Cognitive Spectrum Handover Technology

Miao Dan, Chen Xing

2009, 7(2):  37-41. 

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Based on spectrum sensing, dynamic spectrum allocation and reconfiguration technologies in Cognitive Radio (CR ), this paper fully considers the matching issues between short-term spectrum characteristic and service characteristic. In the communication process, the network-side selects switch terminals to initiate handover command to solve problems due to limited capacity of the system, such as overload and new session decline, improving the success rate of switching on the premise of ensuring user’s QoS, reducing blocking probability with more session admission, eliminating overload, increasing system throughput, and improving the whole system performance.

Research Paper

IPv4 and IPv6 Migration in IMS Environment

Li Mo

2009, 7(2):  42-46. 

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The IP Multimedia Subsystem (IMS ) framework was envisioned to be operating on an IPv6 network. However, when the fixed network started to use IMS framework in the Next Generation Network (NGN ) architecture, the issue of IPv4 and IPv6 interworking becomes more pronounced due to the widespread usage of the IPv4 network. The overall objective of the solution proposed in this article is to minimize the invocation of Network Address and Port Translation Protocol Translation (NAPT-PT ) or Network Address and Port Translation (NAPT ) inside the provider’s network. The solution, outlined by the processing rules contained in this article, will limit the NAPT-PT operation at most once inside the provider’s network under all the situations for the media path. This solution will also introduce the minimum required NAPT operations.

Operational Application

Service Convergence in Next Generation Network

Wang Jun, Fu Tao

2009, 7(2):  47-53. 

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The convergence of communication services becomes a focus in the industry along with the requirement for full-service operation and technical development. Service convergence includes two aspects: The convergence of the fixed and mobile networks; and the convergence of traditional communications and Internet services. This requires balancing the conflicts between the openness and operationability of terminal capability and network convergence. Unified authentication and authorization are the basis for service convergence in terms of operationability. Modular network and open terminal are technical solutions for the service convergence.

Development Field

Open Access Standards for Telecom Service Capabilities

Yang Yong, Jia Xia, Dong Zhenjiang

2009, 7(2):  54-60. 

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Among the open access standards for telecom service capabilities, Java Community Process (JCP ) and Parlay series are two mainstream standards, which provide service capability opening standards at different levels for different user objects. The JCP specifications include Java Specification Request (JSR ) 21, JSR 32, JSR 116 and JSR 289 especially for Java application developers, while Parlay brings out specifications including Parlay and ParlayX. The service capability open technologies feature different benefits and vitality due to their diversified implementations. As the community of service developers is continuously growing and the demands for integrated service development become more and more manifest, fast, effective and easy-to-use open access technologies for telecom service capabilities have become a very important research subject.

Lecture Series

Cooperative Communication and Cognitive Radio (2)

Luo Tao, Hao Jianjun, Yue Guangxi

2009, 7(2):  61-65. 

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