TD-SCDMA系统接力切换研究与仿真

研究了TD-SCDMA系统接力切换算法,包括切换候选小区的选择、Hysteresis-Threshold算法。对算法进行了大量仿真实验,得到在不同业务速率情况下在切换门限参数取值变化时,相应的系统性能参数的变化曲线,给出切换门限参数建议值。     

Handover Optimization in Wireless Microcellular ATM Networks

Microcellular solutions in wireless ATM networks increase the network traffic control as a result of frequent handover requests. The blocking probability or the forced termination probability presents a quality of service criterion for evaluation of certain handover techniques. This paper presents a handover protocol that can avoid cell loss and guarantee cell sequence, and a two layer wireless call admission control is studied, using Markov state diagrams, in order to optimize the performance of wireless ATM networks. Spiros Louvros was born in Corfu island, Hellas in 1971. He received his Bachelor in Physics from the University of Crete, Hellas and his Master in telecommunications from the University of Cranfield, U.K. with a scholarship for graduate studies from the Alexandros Onassis Institution. In 2004 he received his PhD from the University of Patras, Hellas, in mobile communications. He has worked for Siemens as a microwave engineer and for Vodafon-Hellas as a switching engineer. His current occupation is section manager in the Maintenance Department in Cosmote S.A. He has participated in several research projects regarding mobile communications. His area of interest is in mobile networks, telecommunication traffic engineering, wireless ATM and optical communications and is documented by over 30 papers in international literature and conference proceedings. He is member of FITCE and Hellenic Physics Union and he holds a position of external researcher in the Wireless telecommunications Lab of the Electrical Engineering department, University of Patras. Dimitrios Karaboulas was born in Patras-Hellas. He received his diploma in Electrical & Computer Engineering from the University of Patras, Hellas in 1994. He has been working, since 1994, as an external consultant-specialist in several telecommunication companies in Hellas and he currently holds a company firm for ISO certification, supervision and technical solutions. He is currently a PhD candidate in the Wireless Laboratory of Electrical & Computer Engineering Department, University of Patras, Hellas and his research interests are in the area of Wireless ATM networking, mobile communications and telecommunication network planning. He has participated in several research projects regarding mobile communications and enterprise telecommunication solutions and is documented by over 50 papers in conference proceedings. He is also an active member of the Technical Chamber of Greece. S. Kotsopoulos was born in Argos-Argolidos (Greece) in the year 1952. He received his B.Sc. in Physics in the year 1975 from the University of Thessaloniki, and in the year 1984 got his Diploma in Electrical and Computer Engineering from the University of Patras. He did his postgraduate studies in the University of Bradford in United Kingdom. And he is an M.Phil and Ph.D. holder since 1978 and 1985 correspondingly. Currently he is member of the academic staff of the Department of Electrical and Computer Engineering of the University of Patras and holds the position of Associate Professor. Since 2004, is the Director of the Wireless Telecommunications Laboratory and develops his professional life teaching and doing research in the scientific area of Telecommunications, with interest in mobile communications, interference, satellite communications, telematics applications, communication services and antennae design. Moreover he is the (co)author of the book titled “mobile telephony”. The research activity is documented by more than 160 publications in scientific journals and proceedings of International Conferences. Associate Professor Kotsopoulos has been the leader of several international and many national research projects. Finally, he is member of the Greek Physicists Society and member of the Technical Chamber of Greece.     

Fast Handover Mechanism for Seamless Multicasting Services in Mobile IPv6 Wireless Networks

This paper proposes a fast handover mechanism to provide a seamless multicast service for Mobile IPv6 hosts. With the proposed Fast handover based on a Mobile IP-Multi casting (FMIP-M) protocol, the selection of a new multicast service method, service preparation, and initialization procedures are all performed during the fast handover period, thereby enabling a reliable and efficient multicast service. When mobile hosts move to other networks, they can encounter data loss, out-of-synch problems for multicast data, and multicast service exchange latency. Therefore, the proposed FMIP-M allows the new access router to select a suitable multicast service method according to the multicast service-related network conditions and supports a reliable multicast transmission by compensating for data losses from the previous access router. An analysis is conducted of the overheads associated with a fast multicast handover, including the signaling cost and multicast packet-forwarding cost, where the costs are formulated based on timing diagrams, and compared with a fast handover using Mobile IPv6. The performance analysis and numerical results confirm that the proposed FMIP-M provides a fast multicast handover and reliable service with a relatively small signaling cost and packet-delivery cost.     

Handover with resource pre-allocation in the OFDMA systems

This article proposed a new handover algorithm for beyond the third generation (B3G) systems with an orthogonal frequency division multiple access (OFDMA) downlink. In the proposed algorithm, handover mobile termination (MT) chooses a subchannel set in the candidate cells by a subchannel booking rule, based on the terminal speed and the subchannel's channel state information (CSI). Moreover, the handover decision is made after analyzing if at least one candidate cell can reserve the subchannel set for the handover user. Simulation results show that the algorithm reduces the number of handovers and guarantees the quality of service (QoS) for the handover users. It yields better system performance in the OFDMA systems.     

Software‐defined networking to improve handover in mobile edge networks

Mobility management and handover for a seamless connection are among all‐time challenges of wireless networks. Software‐defined networking (SDN) has opened new horizons toward research by adding intelligence in edge networks while decoupling the control and data planes. The flexibility and centralized nature of SDN further improve the handover decision algorithms. In this paper, we have improved the network performance with respect to the number of handovers and the handover delay by applying an LTE‐SDN architecture and a novel handover decision algorithm based on predicting the future locations of a moving vehicle. The proposed algorithm decouples the handover procedure into two phases of preparation and execution. In the preparation phase, which occurs in the control plane, the handover decision and resource allocation take place, and in the execution phase, handover gets executed similar to the LTE architecture. The results of our research indicate that our proposed LTE‐SDN performance is improved with respect to the number of handovers, handover delay, and signaling overhead by 24%, 16%, and 20%, respectively. On the other hand, average Reference Signal Received Quality (RSRQ) value is decreased by 4% as a tradeoff for the improvements gained.     

无网格模型的子结构分析

提出一种无网格模型的子结构分析方法。基于界带分析方法,处理无网格模型子结构之间的连接,能够保证各个子结构之间无缝连接,从而使无网格子结构模型与原无网格模型等价,同时还能够降低无网格刚度方程的计算规模。数值算例表明,本文方法是正确可靠的,可以保证各个子结构之间无缝连接。     

A quality-of-service signaling architecture for seamless handover support in next generation,IP-based mobile networks

The coupling of signaling protocols for mobility management and resource reservation plays an important role to achieve Quality-of-Service (QoS) in wireless environments. When performing a handover, request and allocation of resources have to be done in the shortest possible time to avoid disruptions for the user service. Therefore, it is preferable to ensure resource availability in advance, which we call anticipated handover. This approach for providing seamless handovers in turn poses challenges for the overall design of the QoS architecture and its associated QoS signaling protocol. This article describes the design, implementation, and evaluation of a comprehensive QoS architecture and a suitable QoS signaling protocol. It discusses intrinsic problems of reservations in IP based networks such as session ownership as well as a number of protocol design issues regarding the integration of QoS signaling with other protocols, such as Mobile IP. In particular, we define an end-to-end QoS architecture and a mobility-aware reservation signaling protocol Mobility Aware Reservation Signaling Protocol (MARSP) that supports anticipated handover, thus enabling seamless services over heterogeneous wireless access networks. The presented architecture and protocol were implemented and evaluated by measurements. They show that anticipated handovers not only outperform hard handovers regarding handover latency, but that they also provide functional and robustness advantages. Authors Hillebrand and Prehofer changed their affiliation in the meantime, the work described in this paper was carried out during their employment at DoCoMo Communications Laboratories Europe.     

IPv6的移动性支持及其优化

随着IPv6技术的稳步发展以及移动IPv4面临移动性、安全性差等越来越多的问题，移动IPv6由于其优良的性能而日益引起人们的关注。由于目前并未出现移动IPv6的标准，本文根据IETF关于IPv6的移动性支持的草案，首先详细介绍了移动IPv6的基本概念和工作原理，主要包括3个基本功能：路由器搜索、注册和分组传送。然后，文章对移动IPv6的优化问题进行了初步探讨。最后简单分析了移动IPv6技术未来的发展和实现。     

一种新的分层移动IPv6快速切换方案研究

分层移动IPv6快速切换在一定程度上减少了切换延时，但切换过程中由网络层移动检测和使用重复地址检测（DAD）配置一个新转交地址引起的延时对实时业务仍然有很大的影响。为了减轻这些影响，文中提出了一种更加有效的快速邻居发现和DAD机制，减小了切换延时，提高了网络的性能。     

基于多普勒的二维切换预测算法

文中研究了在低轨卫星星座中,星上处理器利用地面移动用户终端上行信号固有的多普勒频移信息预测切换时间的算法,该算法无需用户终端额外辅助。针对DDBHP算法预测误差大、成功率低等问题,提出了二维切换预测（2-DDUHP）算法,分析了解其唯一性,并给出了低复杂度的求解过程。研究表明：该预测算法能在各种仰角和测量条件下稳定工作,并能容忍较大的多普勒测量误差,有较强的实用价值。