【作者】 彭彬；

【导师】 张国平；

【作者基本信息】 华中师范大学 ， 电路与系统， 2006， 硕士

【摘要】 随着计算机和通信技术的发展,移动通信成长迅速,在20多年的时间里从一项新技术发展成为了大规模应用的产业,第三代移动通信系统已成为当今移动通信领域最受关注的话题,WCDMA则以其成熟的技术成为第三代移动通信系统的三大标准之一。 切换是移动通信系统必不可少的功能,当移动用户在跨越小区边界时,移动台的信道可以切换到另外一个小区而维持通信不中断。WCDMA系统中不同小区用户都使用同一频率,这使WCDMA系统可以支持“先连后断”的软切换技术。 本文首先介绍了WCDMA系统软切换的算法及流程,并分析了软切换对系统上、下行链路容量的影响。软切换在提高覆盖与容量的同时,由于占用多个信道资源而增加了系统额外开销及干扰,尤其是对于高比特速率的分组业务,软切换会占用系统过多的无线资源,以及对其它用户造成强干扰,从而导致系统整体性能的下降。 普通软切换策略在收到测量报告后,不会考虑软切换用户所处的业务状态,用统一的门限控制激活集。在此基础上,本文提出了一种针对高比特速率分组业务的切换策略,并从理论和网络仿真两方面对该策略进行了分析。新策略通过对切换用户的业务速率的判断,进而采取相应的切换控制。仿真结果表明了该切换策略在占用系统资源和对其它用户干扰两方面较普通软切换策略均有较大改善,从而证明了其可行性及性能。更多还原

【Abstract】 Mobile cellular communication grew rapidly along with the development of the communication technology, and was changed from a new technology into a massive industry within less than three decades. Nowadays the third generation mobile communication system (3G) has drawn the greatest attention in the field and WCDMA has already become one of the three standard for the 3g mobile communication system due to its mature technology.Handover is the essential functionality for dealing with the mobility of the mobile users, which can make an on-going call to a different sector or cell and maintain a call in progress across cell boundaries in mobile communication. In WCDMA system all users in the different cells share the same frequency spectrum simultaneously. This makes it possible that WCDMA system support the "make-before-break" soft handover.The thesis represents the implementations of handover in detail, including measurement procedures, handover algorithms and typical signaling procedures. And the impact of soft handover on the downlink capacity is well investigated. The macrodiversity gain offered by the selection combining brings benefits to both capacity and coverage. However, in the downlink, the extra resource consumed by the extra downlink channels increases the total downlink interference level. Especially for the high-speed packet traffic, the soft handover consumed too much radio resources, and brings interference to other users, consequently inducing to the decrease of the system performance.On the basis of these work, a new handover policy is proposed for the high-speed packet traffic. The new handover policy considers the traffic speed of moving UE. The performance of the proposed policy is analyzed through theory and simulation. The simulation results indicate that the resource expend and interference are reduced obviously, which proves the feasibility and the better performance of the proposed handover policy.更多还原