基于手机”掉线“及”盲区“的探究2.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Physical science and technology institute Yangtze University,*,The study about cell-phones“fall line”and“blind zone”,（手机“掉线”及“盲区”的探究）,Physical science and technology,institute Yangtze University,物理,0801,班,Speaker,Zhu zhong hu,Physical science and technology institute Yangtze University,Title 1,Title 2,Title 3,Principles of signal transmission,The causes of cell-phones“fall line”and“blind zone”,The strategies of improving the property of Cross-district switch,Contents,Title 4,Summary,1.1 Introduction to the principle of signal transmission,Physical science and technology institute Yangtze University,The spread of mobile phone signals are actually transmitted by electromagnetic wave.,1.2 Signal transmission,Physical science and technology institute Yangtze University,Signal transmission,Surface spread,（地表传播）,Sight transmission,（视距传播）,Waveguide transmission,（波导传播）,Scatter transmission,（散射传播）,2 The causes of cell-phones“fall line”and“blind zone”,Physical science and technology institute Yangtze University,First,Second,Third,Multipath fading,（多径衰落）,Interference factors,（干扰因素）,Shielding effect,（屏蔽效应）,The failure of Cross-district Switch,（越区切换失败）,Fourth,2.4 The failure of Cross-district Switch,Physical science and technology institute Yangtze University,The concept,The category,Failure Analysis,The failure of Cross-district Switch,2.4.1 The concept of Cross-district Switch,When the mobile station from one cell(of a base station or base station coverage area)to another area,in order to maintain uninterrupted communications for mobile users need to change the channel referred to as handoff.,Physical science and technology institute Yangtze University,2.4.2 The category of cross-district switch,(1),Divided by whether the current service station is synchronous(,同步,)with the service station after switching:,absolutely synchronous switching(,完全同步切换）,pre-synchronous switching,（,预同步切换,）,asynchronous switching,（异同步切换）,pseudo-synchronous switching,（伪同步切换）,Physical science and technology institute Yangtze University,(2),According to areas,：,Internal switch,（内部切换）,External switch,（外部切换）,(3),According to the controlling process and switches between different MSC,：,Basic switch,（基本切换）,Follow-up switch,（后续切换）,Physical science and technology institute Yangtze University,2.4.3 Failure Analysis,Physical science and technology institute Yangtze University,If the new service area at this time is very busy,it has no extra channel allocation to users.At this time,the switch of the service area will fail.,Each base station has its own scope.When a user during a call beyond a service area to another service area,the user of the voice channels have to be replaced from the original service area over,3.Improve the handoff performance of communication strategy,Reserved channel program,（,保留信道方案,）,Queuing priority program,（,排队优先权方案,）,Half speed program,（,半速方案,）,Physical science and technology institute Yangtze University,4.Summary,Physical science and technology institute Yangtze University,Through my presentation,I hope you had learnt some common senses:,During a call,y,ou,should be in open area,s,or,less interference places,；,if you face the drop,p,ed,problem,s,you can change the location,and n,ever own the reason to your cellphone,.,Thanks for,your attention,Physical science and technology institute Yangtze University,