Quality of Service Improvement for High-Speed Railway Communications

With the fast development of highspeed railways, a call for fulfilling the notion of communication at ＂anytime, anywhere＂ for high-speed train passengers in the Train Operating Control System is on the way. In order to make a realization of that, new railway wireless communication networks are needed. The most promising one is the Long Term Evolution for Railway which will provide broadband access, fast handover, and reliable communication for high mobility users. However, with the increase of speed, the system is subjected to high bit error rate, Doppler frequency shift and handover failure just like other system does. This paper is trying to solve these problems by employing MIMO technique. Specifically, the goal is to provide higher data rate, higher reliability, less delay, and other relative quality of services for passengers. MIMO performance analysis, resource allocation, and access control for handover and various services in a two-hop model are proposed in this paper. Analytical results and simulation results show that the proposed model and schemes perform well in improving the system performances.     

多媒体通信网网管系统体系结构的研究

从网络管理的角度,提出了多媒体通信网层网络结构;基于该结构,提出了多媒体通信网网管系统的体系结构,重点讨论了其中系统结构和管理接口;最后,讨论了多媒体通信网网管系统中ＡＴＭ传送层网络网管系统的实现技术,并介绍了有关的实验。     

协同传感器管理体系结构及方法

对协同传感器管理的基本概念、原理以及重要性进行了简述,给出了协同传感器管理的体系结构,对协同传感器管理的基本方法进行了分析与综合,指出了协同传感器方法发展的基本特征和需要进一步研究的问题。     

无线市话业务管理系统

介绍了应用计算机网络系统实现天津市通信公司无线市话“小灵通”业务的实时联机处理。该系统采用本地网数据集中方式，完成无线市话业务的闭环管理，实现多种灵活的营销策略，充分满足不同用户对通信业务的需求。     

移动网间号码携带业务受理体系通信机制

介绍了移动网间号码携带业务受理体系所使用的通信机制,着重介绍了这套通信机制的框架,选用的业务承载协议,NP业务消息和参数的定义方式,以及一些特殊的设计元素。     

"新视通"业务质量提升解决方案

从电信运营商角度,针对当前视频类业务在使用中出现的诸如马赛克、延时等问题,进行初步的研究分析,并结合当前互联网现状,提出提高视频类业务质量切实可行的技术方法     

Auction-Based Resource Allocation for Cooperative Communications

Distributed and efficient resource allocation is critical for fully realizing the benefits of cooperative communications in large scale communication networks. This paper proposes two auction mechanisms, the SNR auction and the power auction, that determine relay selection and relay power allocation in a distributed fashion. A single-relay network is considered first, and the existence and uniqueness of the Nash Equilibrium (i.e., the auction?s outcome) are proved. It is shown that the power auction achieves the efficient allocation by maximizing the total rate increase, and the SNR auction is flexible in trading off fairness and efficiency. For both auctions, the distributed best response bid updates globally converge to the unique Nash Equilibrium in a completely asynchronous manner. The analysis is then generalized to networks with multiple relays, and the existence of the Nash Equilibrium is shown under appropriate conditions. Simulation results verify the effectiveness and robustness of the proposed algorithms.     

Decomposed LT Codes for Cooperative Communications

In order to reduce computation complexity and latency in cooperative communication system based on fountain code, a decomposed LT codes (DLT) based cooperative transmission scheme was proposed. The scheme comprises of two layers of random encoding but only a single layer of decoding. A general decomposition technique for the decomposed LT codes construction is developed. The transmission latency for the proposed scheme was analyzed. Simulation results show that the total time consumed under the proposed scheme can be significantly reduced compared to direct transmission and conventional cooperative transmission based on LT codes in the medium to high packet erasure rate regimes. Moreover, With the increase of packet erasure rate, the advantage of the proposed scheme is more evident.     

Cooperative Communications for Cognitive Radio Networks

Cognitive radio is an exciting emerging technology that has the potential of dealing with the stringent requirement and scarcity of the radio spectrum. Such revolutionary and transforming technology represents a paradigm shift in the design of wireless systems, as it will allow the agile and efficient utilization of the radio spectrum by offering distributed terminals or radio cells the ability of radio sensing, self-adaptation, and dynamic spectrum sharing. Cooperative communications and networking is another new communication technology paradigm that allows distributed terminals in a wireless network to collaborate through some distributed transmission or signal processing so as to realize a new form of space diversity to combat the detrimental effects of fading channels. In this paper, we consider the application of these technologies to spectrum sensing and spectrum sharing. One of the most important challenges for cognitive radio systems is to identify the presence of primary (licensed) users over a wide range of spectrum at a particular time and specific geographic location. We consider the use of cooperative spectrum sensing in cognitive radio systems to enhance the reliability of detecting primary users. We shall describe spectrum sensing for cognitive radios and propose robust cooperative spectrum sensing techniques for a practical framework employing cognitive radios. We also investigate cooperative communications for spectrum sharing in a cognitive wireless relay network. To exploit the maximum spectrum opportunities, we present a cognitive space–time–frequency coding technique that can opportunistically adjust its coding structure by adapting itself to the dynamic spectrum environment.      

垂直交换管理的集合架构

Recent advances in hardware technology have made it possible for mobile devices to interface with multiple networks of different types. In this paper, an IEEE 802.21 Media Independent Handover (MIH) based handover management architecture containing four modules is proposed and the multihoming technology is adopted to achieve Make-Before-Break vertical handover. Then the paper presents the performance analysis of the architecture and simulation in ns-2. The results substantiate the effi cacy of the architecture in improving the handover performance signifi cantly compared with the traditional Mobile IPv6 (MIPv6) based vertical handover. Besides, we design and implement this handover management architecture in our test-bed. The experimental results in a real network environment show that our proposed architecture can not only support the Make-before-break handover, but also guarantee the scalability because of the modulized design.     

一种分布式喷泉码在协作通信中的应用

为了减少基于数字喷泉码的协作传输系统中的计算复杂度和传输延迟,提出了一种基于分布式喷泉码的协作通信传输方案,给出了两层数字喷泉编码的度分布函数的设计过程;以各链路的丢包率为参量分析了系统传输时延,并与其他数字喷泉码传输方案进行了比较.理论分析和仿真结果表明,在各链路丢包率较大时采用这种分布式喷泉码的协作传输机制能在传输时延上显著改善系统性能,而且各链路删除概率越大时优势越明显.     

A New Network Architecture for Wireless Communications

Current cellular systems are based on theconcept of the cell. Although the cell allows channelreuse, it has also become a metaphor for channelconfinement and leads to the thorny problem of handoffand call dropping. The problem will get much worseas wireless networks move toward smaller cells andmultirate. A new network architecture for wirelesscommunications is presented in this paper. Thearchitecture — called MAWCC for its main characteristic,MAcrodiversity Without Channel Confinement — hasno ping-pong effect in handoff. Furthermore, itscapacity gain from macrodiversity can be freelyconverted into handoff reduction. The new architecture offers manyoptions to handle mobility which are not possible in aconventional cellular architecture.     

An Adaptive Resource Management Architecture for Active Networks

This paper presents a framework for resource management in highly dynamic active networks. The goal is to allocate and manage node resources in an efficient way while ensuring effective utilization of network and supporting load balancing. The framework supports co-existence of active and non-active nodes and proposes a novel Directory Service (DS) architecture that can be used to discover the suitable active nodes in the Internet and for selecting the best network path (end-to-end) and reserving the resources along the selected path. Intranode and internode resource management are facilitated through the DS, while within an active node the framework implements a composite scheduling scheme to schedule both the CPU and bandwidth resources to resolve the combined resource scheduling problems. In addition, a flexible active node database system and a simple adaptive prediction technique have been introduced in order to resolve the challenging problem of determining the CPU requirements of the incoming packets.     

混合业务场景下的合作博弈动态资源管理策略

LTE系统对各类多媒体业务的承载能力对其未来应用至关重要。面向混合业务场景，本文建立了合作博弈模型描述各类业务之间的关系，并提出了一种动态资源管理策略。系统根据当前业务状态为各类业务分配所需资源，进而，根据业务属性确定各个用户的调度优先级。结果表明所提出的资源管理策略能够有效提高系统频谱效率及各类业务的服务质量。     

Priority-Oriented Architecture Service Management on OSGi Home-service Platform

Open Service Gateway initiative (OSGi) platforms integrate a variety of reusable applications and resources, packing them into bundles. These deployed services, which are offered by service providers, can expediently manage home appliances. However, in the user’s daily life, various services or bundles access to other services directly or indirectly, creating a situation that is likely to generate problems involving non-supportable applications or insufficient hardware resources. OSGi platforms are no way to deal with these situations. Although much research has proposed methods to resolve specific issues, almost all of these methods are incomplete or are unsuitable for the limited resources in households. This paper addresses the wide range of such common home-network applications as those involving health care, home automation, and home security; and both our proposed priority-based principles of a management decision-making mechanism and our framework architecture help ensure the quality of service and or emergency responses.     

Complex Field Network Coding for Multiuser Cooperative Communications

Multi-source relay-based cooperative communications can achieve spatial diversity gains, enhance coverage and potentially increase capacity when multiuser detection is used to effect maximum likelihood demodulation. If considered for large networks, traditional relaying entails loss in spectral efficiency that can be mitigated through network coding at the physical layer. These considerations motivate the complex field network coding (CFNC) approach introduced in this paper. Different from network coding over the Galois field, where wireless throughput is limited as the number of sources increases, CFNC always achieves throughput as high as 1/2 symbol per source per channel use. In addition to improved throughput, CFNC- based relaying achieves full diversity gain regardless of the underlying signal-to-noise-ratio (SNR) and the constellation used. Furthermore, the CFNC approach is general enough to allow for transmissions from sources to a common destination as well as simultaneous information exchanges among sources.