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Subject: 计算机应用
Title:
地球同步轨道卫星移动通信系统多波束切换算法研究
Author: 杨丹平
Issued Date: 2014-05-26
Supervisor: 刘立祥
Major: 计算机应用技术
Degree Grantor: 中国科学院大学
Place of Degree Grantor: 北京
Degree Level: 硕士
Keyword: 同步轨道卫星移动通信系统 ; 多波束 ; 功率分配 ; 切换
Abstract:

地球同步轨道卫星移动通信系统是利用静止轨道通信卫星实现各种终端之间通信的系统,它能为全球用户提供大跨度的通信服务,是陆地蜂窝移动通信系统的扩展和延伸。高效准确的切换算法是保证终端服务质量、提高网络性能的关键之一。

不同的移动终端运动模式不同,当移动终端在波束间移动时,为了保持连续通信,就会导致切换的发生。传统的切换算法主要针对中低速终端,并且考虑的切换决策参数单一,不适合于地球同步轨道卫星移动通信系统中。本文针对切换的双向选择性,对地球同步轨道卫星移动通信系统多波束切换算法进行研究。

地球同步轨道卫星多波束通信系统中各点波束功率的分配对切换性能有重要的影响,一方面从电磁波辐射特性可知,发射功率影响通信用户可接收到的信号强度,从而影响用户的切换决策结果;另一方面从香农定理可知,功率影响单点波束可服务的用户总数,若点波束总容量太小,则可能导致向该点波束发起的切换请求被拒绝,从而影响切换结果。因此,本文首先将对点波束功率的分配问题进行研究,提出一种优化的功率分配算法。在考虑总功率限制、通信链路质量、用户最小需求、天线尺寸影响的基础上,本文将基于点波束的优先级,以及系统容量与用户公平之间的折中,提出优化功率分配算法,并进行求解。仿真实验表明,本文提出的优化功率分配算法能平衡系统容量与用户公平,具有较高的功率利用率,以及功率业务匹配度,算法更加灵活。

    在讨论上述问题之后,针对传统算法只考虑单一因素的缺点,本文首先分析了各种起重要作用的切换决策参数,尤其是移动终端速率。然后,基于不同种类业务侧重的指标不同,建立动态改变权重的方法。最后,考虑到切换是一个双向选择的过程,提出一种面向网络收益的动态切换算法,该算法分为两步:第一步是基于用户需求的候选网络评分,在这个阶段用户基于自己的业务特色,动态地对网络做出评判,抉择出最优切换顺序;第二步是基于网络收益的切换判决,在这个阶段网络基于容量的考虑,本着最大化系统收益的原则,对切换用户做出选择。仿真结果表明,本文提出的算法保证了网络收益,提高了切换成功率,并能保障大部分用户的服务质量。
English Abstract:

Geosynchronous satellite mobile communication system is a system which complements communication between different terminals by geostationary communication satellites, it provides a large span of communications service for users, which is the expansion and extension of terrestrial cellular mobile communication system. Efficient and accurate handover algorithm is one of the keys ensuring quality of service and improving network performance.

Different mobile terminals have different types of movement pattern, when the terminal moves between the beams, handover request will be generated in order to maintain continuous communication. The traditional handover algorithms are mainly targeted at the low speed terminals, and the handover decision parameter considering is single, not suitable for geosynchronous satellite mobile communication system. In this paper, we’ll do some further research on the handover algorithm in geosynchronous satellite mobile communication system based on the two-way selection.

In the multi-beam GEO satellite communication system, power allocation plays a key role for handover. On one hand, from the electromagnetic radiation characteristics, we know that transmission power decides the receive signal strength, indirectly effecting the result of handover decision. On the other hand, from Shannon Theorem, we know that transmission power affects system capacity of one spot beam, if the value is too small, the handover request to this beam may be rejected, effecting handover result. Thus, we’ll do some research on the power allocation of multiple beam, and propose an optimized power allocation algorithm. Considering total power limitation, communication link quality, minimum request and antenna size affection, we’ll establish and optimize the power allocation objective function, solve the problem based on beam priority and the balance of maximum system capacity and user traffic. Simulation results show that compared with traditional algorithms, the optimized power allocation algorithm in this paper could balance the various system performance quotas, the algorithm is more flexible with higher power utilization, the matching degree between power and traffic is higher.

After considering the above system problem, we will propose a dynamic handover algorithm orienting the network revenue. First, by analyzing the various handover factors with great importance, especially the terminal velocity, we can improve the shortcomings in traditional algorithms. Then, the algorithm sets factor weights based on different traffic types. Finally, taking into account that handover is a two-way choice process, the optimization algorithm is divided into two steps. The first steps is the ranks of candidate networks according to user demand, in this step, the users dynamically score the network based on traffic characteristics, choose the best network sequence, forming a handover request. The second step is handover decision according to network revenue, in this step, the algorithm employs dynamic programming for maximizing network revenue to obtain the final decision for request. Simulation results show that compared with traditional algorithms, this algorithm could satisfy user demand and network revenue with a high handover success rate.

Language: 中文
Content Type: 学位论文
URI: http://ir.iscas.ac.cn/handle/311060/16390
Appears in Collections:综合信息系统技术国家级重点实验室 _学位论文

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Recommended Citation:
杨丹平. 地球同步轨道卫星移动通信系统多波束切换算法研究[D]. 北京. 中国科学院大学. 2014-05-26.
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