共查询到20条相似文献,搜索用时 78 毫秒
1.
分析比较了地面蜂窝移动通信系统和卫星通信系统在呼叫接入控制中的差异,并在此基础上重点分析讨论了卫星通信系统在呼叫接入控制中所必须考虑的策略。 相似文献
2.
在对移动系统的性能分析中,为了便于分析,通常都没有区分一个小区中切换呼叫和新 呼叫,而是假定它们的信道占用时间具有相同的分布。但在有些实际的系统中,这种假设是不合理的, 两者信道占用时间的均值往往是不同的。设计了一种适用于多业务的呼叫接入控制算法,它对语音业 务基于保护信道法而对语音和数据业务之间采取可移动边界法,并对其性能进行了分析,结果表明切换 呼叫和新呼叫的均值对语音业务和数据业务的性能都具有重要的影响。 相似文献
3.
4.
5.
针对用户终端有效与可靠接入低轨卫星通信网络的需求,基于现有的接入算法,综合考虑了卫星对用户终端的覆盖时间、卫星空闲信道数以及卫星接收信号的信噪比因素,提出了一种改进的综合加权接入算法,对该算法的目标函数和参数进行了设计与计算.仿真结果表明,采用改进的综合加权接入算法,新呼叫阻塞率和强制中断率等性能都得到了明显的改善. 相似文献
6.
以ATM用户接入系统为背景,介绍呼叫接纳控制(CAC)的方法和工作过程。呼叫接纳控制是ATM网络流量控制的基础。呼叫接纳控制模块收到呼叫接纳请求后,根据新连接的流量和业务质量要求以及现有网络资源情况,决定是否接受这一新连接。如果接受,就通知网络为新连接分配网络把新连接的流量参数送交用法接受这一新连的妆。如果接受,就通知网络为新连接网络资源,同时把新连接的流量参数送交用法参数控制(UPC)模块进行流 相似文献
7.
针对 CDMA蜂窝系统区间业务不平衡的情况 ,文中提出了一种呼叫接入控制方案 ,在重负荷小区为邻区即将到来的呼叫预留部分资源 ,预留的大小随呼叫阻塞情况自适应地调整。仿真结果显示 :该方案能很好地解决区间业务不平衡的问题 ,而且与基于固定资源预留的呼叫接入控制方案相比 ,还能获得低的系统呼叫阻塞率 相似文献
8.
9.
低轨卫星(Low Earth Orbital,LEO)通信网络是实现全球无缝覆盖的一种重要方式,是对地面通信网络的有效补充。但卫星与用户之间的相对高速运动造成了服务间断的问题,用户的移动性管理是低轨卫星通信系统运行的基础。分析了低轨卫星移动性管理的发展现状,并从决策因素对移动性管理性能的影响,海量用户、巨型星座的移动性管理,基于人工智能的智能管理等方面对其发展趋势进行了探讨。 相似文献
10.
本文对低轨星座卫星通信系统采用TD-SCDMA多址接入技术的可行性进行了初步论证,通过对低轨星座卫星通信特点的分析,提出在现有TD-SCDMA系统基础上进行适应性改造,满足卫星通信的要求,使得低轨星座卫星通信系统最大限度的重用已有的成熟技术,作为地面移动通信的延伸和补充,这将大大提高低轨星座卫星通信系统的经济性、可运营性、易维护性和可持续发展能力。 相似文献
11.
多业务LEO卫星网络中最优呼叫允许控制及切换管理策略 总被引:2,自引:0,他引:2
该文针对多业务条件下的LEO(Low-Earth-Orbit)卫星网络,提出了一种新的基于最优多门限信道预留(OMTCR)的呼叫允许控制(CAC)及切换管理策略,建立了评价LEO卫星网络连接级QoS性能的理论分析模型框架。借鉴经济学收益函数的概念分别建立了无QoS约束和有QoS约束的系统收益目标优化模型,求解在给定系统参数和输入业务条件下OMTCR的最优门限参数矢量。仿真结果表明OMTCR能够在不同用户QoS要求和系统收益目标的多业务环境下获得比传统CS(Completely Sharing)策略及GC(Guard Channel)策略更好的性能。 相似文献
12.
Cho Sungrae Akyildiz Ian F. Bender Michael D. Uzunalioğlu Huseyin 《Wireless Networks》2002,8(4):403-415
Frequent spotbeam handovers in low earth orbit (LEO) satellite networks require a technique to decrease the handover blocking probabilities. A large variety of schemes have been proposed to achieve this goal in terrestrial mobile cellular networks. Most of them focus on the notion of prioritized channel allocation algorithms. However, these schemes cannot provide the connection-level quality of service (QoS) guarantees. Due to the scarcity of resources in LEO satellite networks, a connection admission control (CAC) technique becomes important to achieve this connection-level QoS for the spotbeam handovers. In this paper, a geographical connection admission control (GCAC) algorithm is introduced, which estimates the future handover blocking performance of a new call attempt based on the user location database, in order to decrease the handover blocking. Also, for its channel allocation scheme, an adaptive dynamic channel allocation (ADCA) scheme is introduced. By simulation, it is shown that the proposed GCAC with ADCA scheme guarantees the handover blocking probability to a predefined target level of QoS. Since GCAC algorithm utilizes the user location information, performance evaluation indicates that the quality of service (QoS) is also guaranteed in the non-uniform traffic pattern. 相似文献
13.
LEO/MEO卫星通信系统发展展望 总被引:3,自引:0,他引:3
本简述了LEO/MEO卫星通信系统的主要特点,并介绍了几个典型的LEO/MEO卫星通信系统,如Iridium、Globalstar、ICO、Teledesic、Skybridge系统。还从星座、频率、星上处理及星际链路、无线技术、网络技术等方面讨论了LEO/MEO卫星通信系统的发展趋势和研究热点。 相似文献
14.
15.
基于Globalstar和Odyssey两个Walker delta星座,建立星间链路网络,重点分析网络中的不同轨道间星间链的动态特性,特别是与星上跟瞄系统密切相关的俯仰角、方位角和链路长度变化,为卫星网络路由提供依据.对传统的卫星路由策略作了改进,利用卫星系统的冗余覆盖的特性,选择不同策略下的最优路径.针对用户不能忍受通信中断的情况,提出考虑消除中断的路由策略,进行服务质量的分析比较.同时也比较在消除中断的路由策略下,LEO同MEO网络差异之处.消除通信中断是以其它QoS性能下降为代价. 相似文献
16.
17.
18.
QoS Handover Management in LEO/MEO Satellite Systems 总被引:4,自引:0,他引:4
Low Earth Orbit (LEO) satellite networks are foreseen to complement terrestrial networks in future global mobile networks.
Although space segment topology of a LEO network is characterized by periodic variations, connections of mobile stations (MSs)
to the satellite backbone network alter stochastically. As a result the quality of service delivered to users may degrade.
Different procedures have been proposed either as part of a resource allocation mechanism or as part of an end-to-end routing
protocol to manage transitions of MSs from one satellite to another (handover). All of these techniques are based on the prioritization
of requested handovers to ease network operation and therefore enhance provision of service. This paper proposes a new handover
procedure that exploits all geometric characteristics of a satellite-to-MS connection to provide an equable handover in systems
incorporating onboard processing satellites. Its performance is evaluated by simulations for a variety of satellite constellations
to prove its general applicability.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
20.
ZHUO Yong-ning YAN Shao-hu WU Shi-qi 《中国电子科技》2005,3(4):298-303
The packet reservation multiple access with hindering state (PRMA-HS) is a protocol suitable for LEO satellite mobile communication. Although working well with light system payload (amount of user terminals), the protocol imposes high channel congestion on system with heavy payload, thus degrades the system's quality of service. To controlling the channel congestion, a scheme of enhanced PRMA-HS protocol is proposed, which aims to reduce the collision of voice packets by adopting a mechanism of access control. Through theoretic analysis, the system's mathematic model is presented and the packet drop probability of the scheme is deduced. To testify the performance of the scheme, a simulation is performed and the results support our analysis. 相似文献