A Mobile Agent-based System for Dynamic Task
Allocation in Clusters of Embedded Smart
Cameras
Michael Bramberger1,Bernhard Rinner1and
Helmut Schwabach2
1Institute for Technical Informatics,
Graz University of Technology,Graz,Austria
{bramberger,rinner}@iti.tugraz.at
2Video&Safety Technology,
ARC seibersdorf research,Seibersdorf,Austria
helmut.schwabach@arcs.ac.at
Abstract—This paper presents a dynamic task allocation method for smart cam-
eras targeting traf?c surveillance.Since our target platforms are distributed em-
bedded systems with limited resources,the task allocation has to be light-weight,
?exible as well as scalable and has to support real-time requirements.Therefore,
surveillance tasks are not allocated to smart cameras directly,but to groups of smart
cameras,so called surveillance clusters.We formulate the allocation problem as a
distributed constraint satisfaction problem(DCSP)and present a distributed method
for?nding feasible allocations.Finally,a cost function is used to determine the
optimal allocation of tasks.We have realized this dynamic task allocation using het-
erogeneous,mobile agents which utilize their agencies and our embedded software
framework to?nd the most appropriate mapping of tasks in a distributed manner.The
dynamic task allocation has been implemented on our smart cameras(SmartCam)
which are comprised of a network processor and several digital signal processors
(DSPs)and provide a complex software framework.
1Introduction
Surveillance systems currently undergo a dramatic shift.Traditional surveillance systems of the?rst and second generation have employed analog CCTV cameras,which trans-ferred the analog video data to digital base stations where the video analysis,storage and retrieval takes place.Current semiconductor technology enables surveillance systems to leap forward to third generation systems which employ digital cameras with on-board video compression and communication capabilities.Smart cameras[1][2]even go one step further;they not only capture and compress the grabbed video stream,but also per-form sophisticated,real-time,on-board video analysis of the captured scene.Smart cam-
BRAMBERGER,RINNER,SCHWABACH
eras help in(i)reducing the communication bandwidth between camera and base station, (ii)decentralizing the overall surveillance system and hence to improve the fault toler-ance,as well as(iii)realizing more surveillance tasks than with traditional cameras. Typical tasks to be run in a surveillance system targeting traf?c surveillance include MPEG-4video compression,various video analysis algorithms such as accident detec-tion,wrong-way drivers detection and stationary vehicle detection.Additionally,traf?c parameters such as average speed,lane occupancy and vehicle classi?cation are often required.Since computing power is limited we may not allocate all tasks to the cameras. This paper presents a resource-aware dynamic task allocation system for smart cameras targeting traf?c surveillance.Since our target platforms are distributed embedded systems with limited resources,the task allocation has to be light-weight,?exible,scalable,and has to support real-time requirements.Therefore,surveillance tasks are not allocated to smart cameras directly,but to groups of smart cameras,so called surveillance clusters.We formulate the allocation problem as a distributed constraint satisfaction problem(DCSP) and present a distributed method for?nding feasible allocations.Finally,a cost function is used to determine the optimal allocation of tasks.We have realized this dynamic task allocation using heterogeneous,mobile agents which utilize their agencies and our em-bedded software framework to?nd the most appropriate mapping of tasks in a distributed manner
The main contributions of this ongoing research project include(i)the distributed agent-based approach for determining all feasible allocations of a DCSP,(ii)the evaluation of a complex cost function considering the limited resources of the embedded platform in detail,(iii)the integration of a mobile agent system in our embedded software framework. The dynamic task allocation has been implemented on our smart cameras(SmartCam[3]) which are comprised of a network processor and several digital signal processors(DSPs) and provide a complex software framework.
The remainder of this paper is organized as follows:Section1.1sketches related work. Section2describes the DCSP approach and focuses on?nding feasible allocations of tasks and the cost function.Section3and4present the implementation and the experi-mental results,respectively.Section5concludes the paper with a summary and an outlook on future work.
1.1Related Work
Agents-based load distribution has been an active research in the last decade.An overview of agent standards and available platforms is presented in[4].WY A(While You’re Away)[5]is based on the NOMADS mobile agent system.It provides dynamic load balancing by mobile agents,which utilize a central coordinator to move between work-stations.Qin et al[6]identi?ed the amount I/O-traf?c as an important issue for dynamic load balancing beside CPU-load and memory.Chow and Kwok[7]introduced the af?nity of an agent to its machine and used a credit-based scheme to determine the agents to be migrated by using a central host station.Agents used in surveillance systems were pro-posed by the MODEST consortium[8],where mobile agents were used to track vehicles using PC based platforms.
Distributed constraint satisfaction problems have been analyzed by Yokoo et al.in [9]for variable-split CSPs.The presented asynchronous backtracking algorithm used
DYNAMIC TASK ALLOCATION IN CLUSTERS OF EMBEDDED SMART CAMERAS autonomous agents,however,the high communication effort between the agents is im-practical for real-time systems.
2Task Allocation
The goal of the task allocation system is to ?nd a mapping of tasks to smart cameras which satis?es all requirements and is optimal with respect to a speci?ed metric,i.e.some cost function.Since the surveillance tasks have ?rm real-time requirements,the task allocation system has to take care that no deadlines are missed due to an overload of a camera or a camera’s subsystem,respectively.
The re-allocation of tasks may be necessary due to events,raised by hardware or soft-ware:(1)Hardware events usually originate from changed resource availability due to added or removed cameras,hardware breakdown,or re-usability of recovered resources.
(2)Software events are caused by changes to resource requirements due to changes in the task set of the surveillance cluster,or because of changes in the quality-of-service level (QoS)of tasks,i.e.due to detected events in the observed scene.
The allocation of tasks to smart cameras is done in two steps.(1)In the ?rst step,all fea-sible allocations of tasks to smart cameras (allocations where no real-time requirements are violated)are determined.(2)In the second step,the optimal allocation of tasks is chosen by using a cost function.
2.1Find Feasible Allocations
The determination of feasible allocations of tasks to smart cameras is a distributed con-straint satisfaction problem (CSP)[9].CSPs are de?ned by a set of n variables T ={T 1,...,T n },which hold values of a ?nite domain D ,and a set of k constraints C ={C 1,...,C k }.In our case,the surveillance tasks to be allocated to the cameras of the surveillance cluster are the variables,and the values they hold is the identi?er of the allo-cated smart camera D ={1,...,m }.Therefore,T i =d indicates,that task i is currently allocated to smart camera d .
Equation 1determines all permutations with repetitions A ,denoted by R ,from the m cameras and n tasks.The subsets of A are allocations of tasks to cameras,which have to be checked for feasibility.The constraints (cp.eq.4are formulated using two functions which determine the resource requirements and availability of the tasks and the cameras.req (Res,i )determines the requirements of task i concerning resource Res ,while avail (Res,d )determines the availability of the resource Res on smart camera d .
A =
R (m,n )={A 1,...,A p };p =m n (1)A j ={a 1,...,a n }|a i ∈D (2)R ={CP U,MEM,DMA }(3)C ={?A j ∈A :?d ∈D :?r ∈R :?a i ∈A j ?a i =d :( i req (r,i )) Equations 1to 4de?ne a feasible allocation,i.e.,any allocation A which does not violate any resource constraint C .Note that in our implementation we also considered the DSPs BRAMBERGER,RINNER,SCHWABACH memory hierarchy and several parameters of the DMA subsystem (cp.resource costs in section 2.2.1). However,this approach requires a central host.A more scalable solution is to distribute the CSP to several cameras in the surveillance cluster. 2.1.1The Distributed CSP In order to distribute the determination of feasible allocations to all smart cameras,we split the domain D into m sub-domains D 1,...,D m ,each comprised of a single value D l =l .The set of tasks T remains the same,while the complexity of the constraints is reduced slightly (cp.equation 5). To achieve all possible allocations of tasks,we choose ?0 C ={?A i ∈A :?A i ν∈A i :?a j ∈A i ν:?r ∈R :( j req (r,a j )) Normally,CSPs require that all variables are included in the solutions of the problem,however,in our case this rule would imply that only partial allocations are valid,which include all n tasks of the surveillance cluster.In order to accept task allocations which do not include all tasks,the CSP rules have to be weakened.Even the allocation of no task is a valid allocation,which is reasonable,if a surveillance cluster contains less tasks than smart cameras. 2.1.2Merging of Allocations Finally,m sets of partial task allocations are available (cp.eq.6),which have to be merged in order to ?nd all feasible task allocations. P ={P 1,...,P m };P j ={P j 1,...,P j ν}(6) Consequently,valid task allocations (1)do not allocate tasks to more cameras concur-rently,and (2)include all surveillance tasks. The merging of partial allocations can be done in parallel,as long as rule 1is not violated.However,the ?nal merging process has to obey rule 2too. The merging step of the partial allocations ?nally provides a set of f feasible allocations F ,from which the most appropriate allocation has to be chosen. 2.2Find Optimal Allocation For ?nding the most appropriate allocation of tasks a cost-scheme is used.This cost-calculation scheme includes ?ve cost classes:(1)Resource costs (C R ),(2)data-transfer DYNAMIC TASK ALLOCATION IN CLUSTERS OF EMBEDDED SMART CAMERAS costs(C T),(3)migration costs(C M),(4)af?nity costs(C A),and(5)quality-of-service costs(C QoS).These costs are calculated for every task on every smart camera in the surveillance cluster.Finally,the overall costs are accumulated as enlisted in the set of feasible allocations F.The following section presents the?ve cost classes,however,a more detailed description of the cost calculation can be found in[10]. 2.2.1Cost Calculation To compute the overall cost C T ot of a surveillance task,the cost values of the?ve cost classes are weighted and added: C T ot=k R?C R+k T?C T+k M?C M+k A?C A+k QoS?C QoS(7) Resource Cost The resource costs are composed of four resources:(1)CPU load,(2) memory usage(including memory hierarchy on DSPs),(3)DMA utilization(including channels,reload-tables,and transfer complete codes),and(4)memory bus utilization. Data-Transfer Cost We have de?ned two different types of data transfers:(1)Data entering or leaving the system will usually be transmitted using a network interface,while (2)intermediate data transfers operate internally via PCI bus or directly to memory.To consider the bandwidth of the used interface,the data-transfer cost C T is calculated as the amount of megabytes(MB)transferred,multiplied by a slowness factor depending on the bandwidth of the connection. Migration Cost The migration of tasks between smart cameras is accounted for by the migration costs depending on(1)required data transfer,and(2)the algorithms downtime due to migration. Af?nity Cost Af?nity costs express the priority of tasks inside a surveillance cluster (cluster af?ne tasks),and additionally provide the possibility to bind a surveillance task to a speci?c camera(scene af?ne task),as it is required for tracking tasks,for example. Quality-of-Service Cost In oder to allow a more?ne-grained control over the system, surveillance tasks may feature several quality-of-service(QoS)levels with different qual-ity levels and,therefore,different resource https://www.doczj.com/doc/291818022.html,ually it is desired to run all tasks with highest possible quality,therefore,this cost adds penalty costs if the task should be run with lower QoS-levels(e.g.due to insuf?cient resource availability for running at best quality).These penalty costs and the number of QoS-levels are de?ned by the task designer. 2.3Reallocation Scenarios As mentioned before,two scenarios are possible,where a reallocation of tasks is neces-sary.However,we handle the scenarios differently to improve the performance of the system. BRAMBERGER,RINNER,SCHWABACH Increased Requirements/Decreased Resource Availability Increased requirements or decreased resource availability indicates a higher system load.Therefore,the number of feasible allocations will decrease,since less combinations of tasks will satisfy the con-straints of the CSP.Therefore,the value of the changed resource or availability is updated in the set of feasible allocations F.Finally,the feasible allocations are re-checked and infeasible allocations are removed from F.This re-checking process does not require to recalculate all possible allocations,therefore,the time required for determination of the new allocation is reduced dramatically. Decreased Requirements/Increased Resource Availability In contrast to the upper scenario,the decrease of requirements or increase of resource availability can be seen as a reduced load of the system.Consequently,the number of both,partial and complete, allocations will increase.Therefore,all feasible allocations have to be re-computed.This approach leads to longer execution times,however,as the service quality will rise by this reallocation,the real-time deadlines are not as?rm as in the upper scenario. 3Implementation For the implementation of our surveillance system we have chosen to use mobile agent technology.Mobile agents are most suitable for our system,since they support mobility, autonomy,and platform independence. 3.1Agent System We have chosen to use the diet-agents1system since it includes all required features like mobility,autonomy,and platform independence and is reasonable small,which is in-evitable for embedded systems. However,extensions to the agent system were necessary to add the support for the DSPs,and the decentralized management of the surveillance clusters. DSP Agencies Agencies provide the environment for agents to live in.An extension to standard agencies is required to support multiple surveillance clusters.Therefore,a logical grouping of agents within the agency is desirable.We have implemented a cluster-information agent(CIA),which hosts local knowledge of other cameras belonging to the surveillance cluster,and provides lookup services for agents within the surveillance cluster.The integration of the DSPs into the agent system is done by one DSP integration agent(DIA)per DSP in the system.This DIA is a stationary agent,which manages message registrations,message dispatching,and binary downloads to the DSP. Two basic agent types are deployed within the agent system:(1)Management-oriented SmartCam-agents,which are not included in the task allocation system,and(2)DSP agents,which implement algorithmic functionality to be executed on a DSP.Conse-quently,DSP-agents represent the tasks allocated by the presented allocation system. Therfore the next paragraph focuses on these agents. 1see https://www.doczj.com/doc/291818022.html, DYNAMIC TASK ALLOCATION IN CLUSTERS OF EMBEDDED SMART CAMERAS DSP Agents DSP agents are an enhancement of standard agents,as they are the base of the task allocation system.Therefore,DSP agents include their requirements to the system and their cost parameters.Additionally,the cost calculation functionality is added to these agents.As the computational intensive parts of these agents are executed on the DSPs,the agents contain a binary,which is downloaded to the DSP and dynamically integrated into the system.Therefore,the agents maintains communication channels to the DSP by using the DSP integration-agent(DIA). In case of migration the agent noti?es the DSPs task to stop computation and to trans-mit the persistent intermediate results to the agent.After migration the agent loads the binary to the DSP and transmits the stored intermediate results to the DSP.This enables the algorithm to continue computation or to use the intermediate results as new starting values,respectively. 3.2Task Allocation System This section outlines the actions taken during a recon?guration of a surveillance cluster. Since our goal is a?exible,scalable and distributed implementation we have chosen to realize the task allocation system using mobile agents. A new allocation is always initiated by a smart camera,either due to a hardware event (changes of availability)or a software event(changes of requirements).This camera initiates the reallocation by broadcasting the request-for-requirements to all agents,that encapsulate the surveillance tasks,within the surveillance cluster.After the agents receive this request,they broadcast their requirements to all smart cameras in their surveillance cluster.Additionally,all agents calculate their costs for every smart camera and transmit the cost values to the initiating camera.The smart cameras determine in parallel the partial allocations,which have to be merged in the next step.As the smart cameras are comprised of more DSPs,the partial allocations for the DSPs are merged.To further merge the partial allocations,the half of the smart cameras(determined during the creation of the surveillance cluster)create allocation-merging agents(AMA),which pick up the merged partial allocation and migrate to predetermined smart cameras(which comprise the other half of the surveillance cluster),where they grab the partial allocation,and merge both,the local and the included partial allocations.After the merging process, the agents migrate to the next smart camera,as de?ned by the?xed itinerary,and merge their partial allocation with the partial allocation provided by another AMA.This way the partial allocations are merged to a?nal allocation,whereas the last allocation merge is done on the initiating smart camera.The merging process corresponds to a binary tree, therefore ld(m)(where m is the number of smart cameras)sequential steps have to be done. The initiating smart camera has to determine the most appropriate task allocation,there-fore,the costs,as submitted by the agents,are accumulated for every task allocation. Consequently,the task allocation with the lowest cost is selected as the new task alloca-tion.Since the selection of the most appropriate task allocation is based on the costs of the agents,the desired optimization goal like the number of migrations,degradation of quality-of-service,or balanced use of resources can be achieved by adapting the scaling factors of the cost classes.Finally,the new task allocation is broadcast to all smart cam-eras and agents,which may update their QoS level,or migrate to another smart camera BRAMBERGER,RINNER,SCHWABACH Figure1:The prototype of the smart camera then.To enable the fast recon?guration by removing feasible task allocations,also the set of feasible task allocations is broadcast to all smart cameras in the surveillance cluster after the system has settled. 3.3Hardware Setup To verify,test and evaluate the presented agent system,we have used two hardware plat-forms.A prototype of our smart camera and PCs equipped with DSP boards. The prototype of our smart camera consists of an Intel IXDP425Development Board, which is equipped with an Intel IXP425network processor running at533MHz,as well as two Network Video Development Kits(NVDK)from ATEME.Each board is comprised of a TMS320C6416DSP from Texas Instruments,running at600MHz,with a total of 264MB of on-board memory.Image acquisition is done using the National Semiconduc-tor LM9618monochrome CMOS image sensor,which is connected to one of the DSP boards. Due to the lack of additional smart camera prototypes,we are using two Pentium-III personal computers(PCs)running at1GHz,which are equipped with one Network Video Development Kit(NVDK)from ATEME. 4Experiments In order to verify and evaluate the presented task allocation system,we used the smart camera prototype and two PCs.Consequently,we have setup a surveillance cluster con-taining these three“cameras”.We have used four different agent types for our experi-ments:(1)A MPEG-4video compression agent,(2)a stationary-vehicle detection(StVD) agent,(3)a vehicle count agent,and(4)a vehicle classi?er agent.The MPEG-4agent and the stationary-vehicle detection agent[2]are well tested and evaluated agents,how-ever,the vehicle count and vehicle classify agents only simulated real behavior.A total of six agents have been instantiated from these four classes,where we used three MPEG-agents(as every camera has to transmit a live video stream),and one agent of every other agent-type. Table1enlists the execution times of the two stages of the task allocation.On the PCs DYNAMIC TASK ALLOCATION IN CLUSTERS OF EMBEDDED SMART CAMERAS Case PC PC SmartCam SmartCam Executed by JDK1.4.2JamVM JamVM Native/C++ 1a Partial Allocations(6ag.)20ms14ms79ms13ms 1b Partial Allocations(3ag.)14ms7ms55ms9ms 2a Merge Solutions(6ag.)766ms4852ms21363ms2360ms 2b Merge Solutions(3ag.)9ms5ms31ms4ms 3a Overall running time(6ag.)786ms4866ms21442ms2373ms 3b Overall running time(3ag.)23ms12ms86ms13ms 4Pruning of allocations(6ag.)14ms32ms172ms26ms Table1:Running times of task allocation we have used two Java virtual-machines:(a)Sun’s JDK1.4.2,which uses a just-in-time (JIT)compiler,and therefore reaches better performance values,while(b)the JamVM virtual machine2is designed as an interpreter.JamVM was also used on the prototype of the smart camera(c),and?nally we have implemented the core calculation functions (determine partial allocations,allocation merging)in C++to estimate the maximum per-formance(d). Lines1a,2a,and3a represent the execution times if all six tasks were considered.In a second scenario we have removed the MPEG-4encoding agents from the surveillance cluster,and allocated them statically to the cameras.The results of the dynamic allocation of the resulting three agents is enlisted in lines1b,2b,and3b in table1. Lines1a and1b show that the determination of partial allocations only requires a low amount of time.However,lines2a and2b enlist that the merging process requires most of the computation time.It can be seen,that merging using the JamVM requires up to 21seconds,which is unacceptable.The C++implementation,however,performs better, but also requires about2seconds for computation.The running time of the merging stage rises exponentially with the number of agents and cameras,since the number of feasible allocations rises exponentially,too(e.g.there are2880feasible allocations in case2a). Therefore,a reduction of feasible allocations would yield in better performance. Lines3a and3b enlist the overall execution time,as the sum of?nding the partial allocations and the merging process. Finally,we have also evaluated the performance of the task allocation system at in-creasing system load,in which case the previously determined allocations a rechecked for feasibility.Line4enlists the times required to recheck all2880allocations.Note that even running JamVM on our prototype delivers a new allocation within172ms,which is suf?cient. 5Conclusion In this paper we have presented a resource-aware dynamic task-allocation system target-ing embedded smart cameras.Surveillance tasks are not allocated to the smart cameras directly,but to groups of smart cameras,surveillance clusters,within the tasks are allo-cated by the smart cameras in a distributed manner.We show that the task allocation can 2https://www.doczj.com/doc/291818022.html, BRAMBERGER,RINNER,SCHWABACH be formulated as a distributed constraint satisfaction problem(DCSP)and present a solu-tion for this DCSP.Therefore we combine the results of the DCSP with a cost function to retrieve the optimal allocation of tasks.Finally,we discuss the mobile-agent based im-plementation of the system and present results achieved by evaluation of the implemented system. Future work includes(1)the further evaluation of the system,using more complex scenarios,(2)the tighter combination of?nding feasible allocations and calculating the costs for an allocation in order to delete expensive allocations at an early stage,(3)the test and evaluation of the system in real-world scenarios,and(4)the integration of learning agents into surveillance clusters,which in?uence the behavior of the system by adapting the cost function based on previous behavior,events,and actions. References [1]W.Wolf,B.Ozer,and T.Lv.Smart Cameras as Embedded Systems.IEEE Computer,35(9):48–53, Sep2002. [2]M.Bramberger,J.Brunner,B.Rinner,and H.Schwabach.Real-Time Video Analysis on an Em- bedded Smart Camera for Traffic Surveillance.In Proceedings of the10th IEEE Real-Time and Embedded Technology and Applications Symposium,pages174–181,2004. 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[12] C.S.Regazzoni,V.Ramesh,and G.L.Foresti.Introduction of the special issue.Proceedings of the IEEE,89(10),Oct2001. 移动通信技术习题册 第一部分：移动通信概念 一、单项选择题 1.所谓个人通信，指的就是简称为“5W”的（B ） A、who，when，where，which，what B、whenever，wherever，whoever，whomever，whatever C、whomever，wherever，whichever，whenever，whatever D、however，whenever，whoever，whichever，whomever 2.移动通信存在严重的多径问题，造成信号电平的起伏不定，因此，移动通信系统在设计的时候必须具有（ C ） A、抗噪声能力 B、抗干扰能力 C、抗衰落能力 D、抗多径能力 3.下面不属于第一代移动通信系统的是（ C ） A、AMPS B、TACS C、PDC D、NMT 4.1989年，我国原邮电部引进了第一个模拟移动通信系统（ A ） A、TACS B、GSM C、CDMA D、PHS 5.下面不属于数字蜂窝移动通信系统结构中网络子系统的是（ B ） A、EIR B、OSS C、AUC D、MSC 6.MSC可以分成三类，分别是普通MSC以及（ C ） A、AMSC和BMSC B、EMSC和FMSC C、GMSC和TMSC D、OMSC和PMSC 7.HLR中存储的用户数据主要包括用户信息和（ A ） A、位置信息 B、鉴权信息 C、设备信息 D、通话记录 8.VLR服务于其控制区的移动用户，它是一个（ B ） A、静态用户数据库 B、动态用户数据库 C、混合态用户数据库 D、半动态用户数据库 9.基站子系统中，一个BSC可以控制（ D ）BTS。 A、一个 B、两个 C、四个 D、多个 10.操作维护子系统的工作任务不包括（ C ） A、网络监视 B、性能管理 C、用户鉴权 D、网络操作 11.主叫用户为呼叫移动用户所需要的拨叫是（ C ） A、TMSI B、IMSI C、MSISDN D、LAI 12.移动用户的ISDN码中，我国的国家码是（ A ） A、86 B、83 C、46 D、18 13.语音编码器有三种类型，不包括（ C ） A、混合编码 B、波形编码 C、图像编码 D、参量编码 14.信道编码主要应对由于噪声引起的（ A ） A、随机误码 B、突发误码 C、冗余码元 D、群误码 15.交织用于应对误码中的（B ） A、随机误码 B、突发误码 C、冗余误码 D、打孔误码 16.均衡的意义在于利用均衡器产生（C ），解决传输中的差错。 A、信号波形 B、相干信号 C、信道模型 D、语音编码 17.移动通信的基本业务包括（ D ） A、业务 B、短消息业务 C、传真 D、以上全部 二、填空题 1.移动通信按照信号性质进行划分，可以分成模拟制和数字制，其中第 AN EXCITING JOB I have the greatest job in the world. I travel to unusual places and work alongside people from all over the world. Sometimes working outdoors, sometimes in an office, sometimes using scientific equipment and sometimes meeting local people and tourists, I am never bored. Although my job is occasionally dangerous, I don't mind because danger excites me and makes me feel alive. However, the most important thing about my job is that I help protect ordinary people from one of the most powerful forces on earth - the volcano. I was appointed as a volcanologist working for the Hawaiian V olcano Observatory (HVO) twenty years ago. My job is collecting information for a database about Mount Kilauea, which is one of the most active volcanoes in Hawaii. Having collected and evaluated the information, I help other scientists to predict where lava from the volcano will flow next and how fast. Our work has saved many lives because people in the path of the lava can be warned to leave their houses. Unfortunately, we cannot move their homes out of the way, and many houses have been covered with lava or burned to the ground. When boiling rock erupts from a volcano and crashes back to earth, it causes less damage than you might imagine. This is because no one lives near the top of Mount Kilauea, where the rocks fall. The lava that flows slowly like a wave down the mountain causes far more damage because it 思考题1答案 1.1简述移动通信的特点。 答：移动通信的主要特点如下： （1）移动通信利用无线电波进行信息传输。移动通信中基站至用户之间必须靠无线电波来传送消息。然而无线传播环境十分复杂，导致无线电波传播特性一般很差，另外，移动台的运动还会带来多普勒效应，使接收点的信号场强振幅、相位随时间地点而不断地变化，严重影响了通信的质量。这就要求在设计移动通信系统时，必须采取抗衰落措施，保证通信质量； （2）移动通信在强干扰环境下工作，主要干扰包括互调干扰，邻道干扰和同频干扰等； （3）通信容量有限。频率作为一种资源必须合理安排和分配，为满足用户需求量的增加，只能在有限的已有频段中采取有效利用频率措施，如窄带化、频道重复利用、缩小频带间隔等方法来解决； （4）通信系统复杂。由于移动台在通信区域内随时运动，需要随机选用无线信道，进行频率和功率控制、地址登记、越区切换及漫游存取等跟踪技术。这就使其信令种类比固定网要复杂的多。在入网和计费方式上也有特殊的要求，所以移动通信系统是比较复杂的； （5）对移动台的要求高。移动台长期处于不固定位置，外界的影响很难预料，这要求移动台具有很强的适应能力。此外，还要求性能稳定可靠、携带方便、小型、低功耗及能耐高、低温等。同时，要尽量使用户操作方便，适应新业务、新技术的发展，以满足不同人群的使用。这给移动台的设计和制造带来很大的困难。 1.3 简述蜂窝式移动通信的发展历史，说明各代移动通信系统的特点。 答：第一代（1G）以模拟式蜂窝网为主要特征，是20世纪70年代末80年代初就开始商用化的。其中最有代表性的是北美的AMPS（Advanced Mobile Phone System）、欧洲的TACS （Total Access Communication System）两大系统，另外还有北欧的NMT及日本的HCMTS 系统等。 从技术特色上看，1G以解决两个动态性中最基本的用户这一重动态性为核心并适当考虑到第二重信道动态性。主要是措施是采用频分多址FDMA方式实现对用户的动态寻址功能，并以蜂窝式网络结构和频率规划实现载频再用方式，达到扩大覆盖服务范围和满足用户数量增长的需求。在信道动态特性匹配上，适当采用了性能优良的模拟调频方式，并利用基站二重空间分集方式抵抗空间选择性衰落。 第二代（2G）以数字化为主要特征，构成数字式蜂窝移动通信系统，，它于20世纪90年代初正式走向商用。其中最具有代表性的有欧洲的时分多址（TDMA）GSM（GSM原意为Group Special Mobile，1989年以后改为Global System for Mobile Communication）、北美的码分多址（CDMA）的IS-95两大系统，另外还有日本的PDC系统等。 从技术特色上看，它是以数字化为基础，较全面地考虑了信道与用户的二重动态特性及相应的匹配措施。主要的实现措施有：采用TDMA（GSM）、CDMA（IS-95）方式实现对用户的动态寻址功能，并以数字式蜂窝网络结构和频率（相位）规划实现载频（相位）再用方式，从而扩大覆盖服务范围和满足用户数量增长的需求。在对信道动态特性的匹配上采取了下面一系列措施： （1）采用抗干扰性能优良的数字式调制：GMSK（GSM）、QPSK（IS-95），性能优良的抗干扰纠错编码：卷积码（GSM、IS-95）、级联码（GSM）； （2）采用功率控制技术抵抗慢衰落和远近效应，这对于CDMA方式的IS-95尤为重要； 《移动通信》复习试题及答案 练习一 一、填空题 1、移动通信按工作方式分（单工）（双工）（半双工）。 2、移动通信按多址方式分（FDMA）,（TDMA）,（CDMA）。 3、移动通信按信号形式分（模拟网）（数字网） 4、移动通信按覆盖范围分（城域网）（局域网）（广域网）。 5、移动通信按业务类型分（PSTN），（DDN），（ISDN） 6、移动通信按服务特性分（专用网），（公用网）。 7、移动通信按使用环境分（陆地通信），（海上通信），（空中通信）。 8、移动通信按使用对象分（民用系统），（军用系统）。 二、简答题 1、什么叫移动通信？ 答：通信双方至少有一方处在移动情况下(或临时静止)的相互信息传输和交换。 2、移动通信的特点。 答：1、移动通信必须利用无线电波进行信息传输 2、移动通信是在复杂的干扰环境中运行的 3、移动通信可以利用的频谱资源非常有限 4、移动通信系统的网络结构多种多样，网络管理和控制必须有效 5、移动台必须适合于在移动环境中使用 3、移动通信的发展趋势。 答：1、开发更高频段2、有效利用频谱 3、数字化 4、向个人移动通信发展 5、传输数据速率越来越高。 4、全球3G的三大标准是什么？答：WCDMA、CDMA2000、TD-SCDMA。 5、什么是基站？ 答：固定不动接发移动台的信号完成与交换中心相连，从而实现移动台信号的收发。 6、什么是移动台？ 答：接收发送无线信号并且可以移动的终端；包括：手机，车载台、无绳电话等。 7、什么是交换中心？ 答：交换各种信息的中心，分为有线和无线。无线交换中心为各个移动台所在的基站之间提供交换服务。 9、数字移动通信系统有哪些优点？ 答：频谱利用率高、容量大，同时可以自动漫游和自动切换，通信质量好，加上其业务种类多、易于加密、抗干扰能力强、用户设备小、成本低。 10、移动通信有哪些主要技术？ 移动通信技术的现状与发展-标准化文件发布号：（9456-EUATWK-MWUB-WUNN-INNUL-DDQTY-KII 下一代互联网技术大作业 题目移动通信技术的现状与发展 姓名 专业网络工程 班级 1402班 学号 1. 移动通信技术的概念及相关知识 1.1 移动通信的基本概念 移动通信是指通信中的移动一方通过无线的方式在移动状态下进行的通信，这种通信方式可以借助于有线通信网，通过通信网实现与世界上任何国家任何地方任何人进行通信，因此，从某种程度上说，移动通信是无线通信和有线通信的结合。移动通信的发展先后经历了第一代蜂窝模拟通信，第二代蜂窝数字通信，以及未来的第三代多媒体传输、无线Internet等宽带通信，它的最终目标是实现任何人在任何时间任何地点以任何方式与任何人进行信息传输的个人通信。 1.2移动通信的发展 目前，移动通信已从模拟通信发展到了数字移动通信阶段，并且正朝着个人通信这一更高级阶段发展。未来移动通信的目标是，能在任何时间、任何地点、向任何人提供快速可靠的通信服务。1978年底，美国贝尔实验室研制成功先进移动电话系统（AMPS），建成了蜂窝状模拟移动通信网，大大提高了系统容量。与此同时，其它发达国家也相继开发出蜂窝式公共移动通信网。这一阶段的特点是蜂窝移动通信网成为实用系统，并在世界各地迅速发展,这个系统一般被当作是第一代移动通信系统。 从20世纪80年代中期开始，数字移动通信系统进入发展和成熟时期。蜂窝模拟网的容量已不能满足日益增长的移动用户的需求。80年代中期，欧洲首先推出了全球移动通信系统（GSM：Global System for Mobile）。随后美国和日本也相继指定了各自的数字移动通信体制。20世纪90年代初，美国Qualcomm 公司推出了窄带码分多址（CDMA：Code-Division Multiple Access）蜂窝移动通信系统，这是移动通信系统中具有重要意义的事件。从此，码分多址这种新的无线接入技术在移动通信领域占有了越来越重要的地位。些目前正在广泛使用的数字移动通信系统是第二代移动通信系统。 2012-2013学年09级《移动通信》复习题及参考答案 第一章 概论 1、什么叫移动通信?移动通信有哪些特点？ 【答】 移动通信是指通信双方至少有一方在移动中（或者临时停留在某一非预定的位置上）进行信息传输和交换，这包括移动体（车辆、船舶、飞机或者行人）和移动体之间的通信，移动体和固定点（固定无线电台或有线用户）之间的通信。 特点： 1、移动通信必须利用无线电波进行信息传输； 2、移动通信是在复杂的干扰环境中运行的； 3、移动通信可以利用的频谱资源非常有限，而移动通信业务量的需求却与日俱增； 4、移动通信系统的网络结构多种多样，网络管理和控制必须有效； 5、移动通信设备(主要是移动台)必须适于在移动环境中使用。 2、单工通信与双工通信有何区别？各有何优缺点？ 【答】 所谓单工通信，是指通信双方电台交替地进行收信和发信。此工作方式设备简单，功耗小，但操作不便，通话时易产生断断续续的现象。它一般应用于用户少的专用调度系统。 所谓双工通信，是指通信双方可同时进行传输消息的工作方式，有时亦称全双工通信。这种方式操作方便，但电能消耗大。模拟或数字式的蜂窝电话系统都采用双工制。 第二章 调制解调 1、移动通信中对调制解调技术的要求是什么？（请总结3G ，LTE 等高速数据传输对调制解调技术的要求） 【答】 已调信号的频谱窄和带外衰减快（即所占频带窄，或者说频谱利用率高）；易于采用相干或非相干解调；抗噪声和抗干扰的能力强；以及适宜在衰落信道中传输。 已调信号所占的带宽要窄：频谱主瓣窄； 已调信号频谱副瓣的幅度要低，辐射到相邻频道的功率就小； 经调制解调后的输出信噪比（S/N ）较大或误码率较低。 1、所有的技术必须在规定频带内提供高的传输效率 2、要使信号深衰落引起的误差数降至最小 3、应使用高效率的放大器 4、在衰落条件下获得所需要的误码率 2、已调信号的带宽是如何定义的？FM 信号的带宽如何计算？ 【答】已调信号的带宽是指已调信号所包含的各种不同频率成分所占据的频率范围。 )(2)1(2m m f FM f f f m B +?=+= 移动通信技术期末考试题（附自整理无误答案，知识点全） 一、填空、判断与选择部分（此部分知识点通用） 1.HLR的全称是__归属位置寄存器____； 2.GMSC全称是 ____移动关口局______； 3.用户手机和GSM系统网络部分的互通接口是__Um____接口； 4.利用一定距离的两幅天线接收同一信号，称为___空间____分集； 5.与CDMA蜂窝系统不同，4G移动通信网的物理层以OFDM 技术为核心，以MIMO 向技术为辅助。； 6.CDMA系统的一个载频信道宽是___1.2288____MHz； 7.CDMA系统前向信道有___64__个正交码分信道；CDMA前向控制信道由导频信道、同步信道和寻呼信道等码分信道组成，CDMA系统中的前向业务信道全速率是__9.6____kbps； 8.GSM系统的载频间隔是___200___kHz； 9.IS-95CDMA是属于第__2__代移动通信系统； 10.3G主流技术标准包括___CDMA200__、__TD-SCDMA__和__W-CDMA_。 11.移动通信采用的常见多址方式有__FDMA_、___TDMA___和__CDMA___； 12.GSM网络系统有四部分，分别是:___NSS__、__BSS_、__MSS_和__OMS_； 13.基站BS是由__BST__和_____BSC____组成的； 14.常用的伪随机码有__m序列码___和___gold码___； 15.SDCCH指的是_____慢速随路控制____信道； 16.TD-SCDMA采用的是__智能____天线，工作方式是___FDD___模式；移动通信中的干扰主要是_同频干扰__、__邻频干扰__和__互调干扰__； 17.一般GSM网络中基站采用的跳频方式是___基带____跳频； 18.GSM采用的调制方式为__GMSK_____； 19.天线分集、跳频能克服___多径____衰落，GSM采用的跳频为___慢跳频___。当移动台接入网络时，它首先占用的逻辑信道是___BCCH____； 20.中国的移动国家代码为_460_，中国联通移动网的移动网络代码为__01_； 21交织的作用可以降低信道__突发性干扰___带来的影响； 22.在3G系统里面，主流的基站配置是___三____扇区； 23.我国GSM系统采用频段为900/1800MHz，可分为_124__个频道，收发双工间隔为__45MHZ，_载频间隔间隔为__20KHZ__； 24.按无线设备工作方式的不同，移动通信可分为_单工、半双工、全双工三种方式； 25.无线通信的三种常见“效应”是：阴影效应、远近效应、多普勒效应； 26.忙时话务量是指__单位小时内呼叫次数与每次呼叫的平均时间的积，其单位是_ Erl___； 27.国产4G的制式是_ TDD-LTE_____。 专业：移动通信科目：移动通信技术 一、单项选择题 1．GSM网络结构中，Abis接口是（）的接口 A．MSC与HLR B．MSC与VLR C．MSC与BSC D．BSC与BTS 答案：D 2．对讲机属于那种通信方式（） A．半双工通信 B．全双工通信 C．单工通信 D．三工通信 答案：A 3．GSM系统对于话务量密集的局部地区，可以采用六列向小区。此时需要采用（）度定向天线 A．360 B．60 C．180 D．120 答案：B 4．实际工程一般要求天线间距大于（）倍信号波长 A．2 B．5 C．10 答案：C 5．GSM网络一般采用列向小区，即天线采用（）度定向天线，把基站分成3个扇形小区 A．360 B．120 C．180 D．60 答案：B 6．CDMA系统容量是模拟系统的（）倍 A．1~2 B．100~200 C．1000~2000 D．10~20 答案：D 7．GSM系统容量是模拟系统的（）倍左右 A．4 B．2 C．3 D．1 答案：B 8．GSM系统信号带宽为（）KHz。 A．200 B．2 C．20 答案：A 9．有线电视属于那种通信方式（） A．全双工通信 B．单工通信 C．半双工通信 D．三工通信 答案：B 10．GSM规范中规定：邻频道干扰保护比，C/I > 负（）dB A．6 B．9 C．12 D．3 答案：B 11．无线电广播采用（）方式 A．CDMA B．SDMA C．TDMA D．FDMA 答案：D 12．GSM是一个典型的（）多址系统 A．FDMA B．TDMA C．SDMA D．CDMA 答案：B 13．GSM网络结构，A接口是（）之间的接口A．BSC与BTS B．MSC与VLR C．MSC与HLR D．MSC与BSC 答案：D 14．无线广播属于那种通信方式（） A．三工通信 B．单工通信 C．全双工通信 D．半双工通信 答案：B 15．GSM规范中规定：同频道干扰保护比，C/I >（）dB A．6 B．3 C．12 D．9 答案：D 二、多项选择题 1．3G技术要求有哪些（） A．支持多媒体业务 B．上下行不对称 C．速度按需分配 D．OFDM 移动通信技术参考答案 第一章 思考题与练习题 1-1 什么是移动通信？移动通信有那些特点？ 答：移动通信是指通信的双方，或至少一方，能够在移动状态下进行信息传输和交换的一种通信方式。移动通信的特点是通信双方不受时间及空间的限制、随时随地进行有效、可靠、安全的通信。频率 1-2 移动通信系统发展到目前经历了几个阶段？各阶段有什么特点？ 答：移动通信系统发展到目前经历了四个阶段，分别为公用汽车电话、第一代通信技术（1G）、第二代通信技术（2G）、第三代通信技术（3G）。特点分别为，公用汽车电话的特点是应用范围小、频率较低、语音质量较差、自动化程度低。第一代通信技术（1G）的特点是该系统采用模拟技术及频分多址技术、频谱利用率低、系统容量小抗干扰能力差、保密性差：制式不统一、互不兼容、难与ISDN兼容、业务种类单一、移动终端复杂、费用较贵。第二代通信技术（2G），采用数字调制技术和时分多址（TDMA）、码分多址技术（CDMA）等技术、多种制式并存、通信标准不统一、无法实现全球漫游、系统带宽有限、数据业务单一、无法实现高速率业务。第三代通信技术（3G）的特点是能提供多种多媒体业务、能适应多种环境、能实现全球漫游、有足够的系统容量等。 1-3 试述移动通信的发展趋势和方向。 答：未来移动通信将呈多网络日趋融合、多种接入技术综合应用、新业务不断推出的发展趋势。移动通信的发展方向是功能一体化的通信服务、方便快捷的移动接入、形式多样的终端设备、自治管理的网络结构。 1-4 移动通信系统的组成如何？试述各部分的作用。 答：移动通信系统的组成主要包括无线收发信机、交换控制设备和移动终端设备。无线收发信机的作用是负责管理网络资源，实现固定网与移动用户之间的连接，传输系统信号和用户信息。交换控制设备的作用是实现用户之间的数据信息交换。移动台的作用是实现移动通信的终端设备。 1-5 常见的移动通信系统有那些？各有何特点？ 答：常见的移动通信系统有：1、蜂窝移动通信系统2、无线寻呼系统3、无绳电话系统蜂窝移动通信系统的特点是越区交换、自动和人工漫游、计费及业务统计功能。无线寻呼系统的特点是即可公用也可专用。无绳电话系统的特点是携带使用方便。 1-6 集群移动通信系统的组成有那些？ 答：集群移动通信系统的组成有移动台、基站、调度台以及控制中心组成。 1-7 移动通信的工作方式及相互间的区别有那些？ 答:移动通信的工作方式有单工制、半双工制、双工制。单工制的优点主要有：1、系统组网方便2、由于收发信机的交替工作，所以不会造成收发之间的反馈3、发信机工作时间相对可缩短，耗电小，设备简单，造价便宜。单工制的的缺点是：1、当收发使用同一频率时，临近电台的工作会造成强干扰2、操作不方便，双方需要轮流通信，会造成通话人为的断断续续3、同频基站间的干扰较大。半双工制的优点主要有：1、设备简单、省电、成本低、维护方便，临近电台干扰小2、收发采用异频，收发频率各占一段，有利于频率协调和配置3、有利于移动台的紧急呼叫。半双工制的缺点是移动台需按键讲话，松键收话。使用不方便，讲话时不能收话，故有丢失信息的可能。双工制的优点有：1、频谱灵活性高2、 移动通信期末复习资料 一、名词解释题 1 、移动通信 是指通信双方中，至少有一方在移动之中，进行信息传输和交换，包括移动体和移动体之间的通信。 2 、信道编码 对要在信道中传送的数字信号进行的纠、检错编码。 3 、越区切换 是指将一个正在进行中的呼叫和通信从一个信道、小区过渡至另一个信道、小区，并且保证通信不产生中断的一项技术。 4 、阴影衰落 移动通信中，由障碍物阻挡造成的阴影效应，接受信号强度下降，但该场强中值随地理改变缓慢变化，称阴影衰落。 5 、双工通信 指通信双方的收发信机均同时工作。同时工作,即任一方在发话的同时,也能收到对方同时工作时无需“按-讲”开关,和市内电话类似。 二、填空题 1、移动通信系统按传递信号的不同，可分为模拟信号和数字信号。 2、为了解决蜂窝移动通信网中有限频率资源和不断增长的用户要求矛盾，采取了小区分裂和 频率复用两种技术。 3、移动通信按多址方式不同可分为频分多址、时分多址和码分多址。 4、移动通信的工作方式有单工通信、双工通信和半双工通信。 5、移动通信的噪声主要有内部噪声和外部噪声，外部噪声主要有自然噪声和人为噪 声。 6、无线电波由于传输路径不同，可分为直射波、反射波、折射波、散射波和绕射波。 7、无线电波从发射到接收之间，收、发信号会受到衰落和延时的干扰，一般将这种干扰称为多径 效应。 8、移动通信中的分集接收方式有宏分集和微分集。微分集又分为空间分集、频率分 集、时间分集。 9、移动通信在其发展的进程中，容量范围基本上形成了以欧洲、北美和日本三大实业 集团。 10、移动通信系统中的用户终端主要指车载台、手机和对讲机，这三种终端的主要区别是功 率大小不一样、无线结构不一样。 11、无线电通信电波在系统传输中，接收端的信号会受到衰落和时延的干扰。 12、移动通信系统中为了使用户通信连续有效，则网络系统应具备越区切换、漫游功能和 位置管理三种基本功能。 13、移动通信中的干扰有邻道干扰、同频干扰、互调干扰、多址干扰等。 14、移动通信按服务范围和对象可分为专用移动网和公用移动网。 15、移动通信系统逐步向着数字化、智能化、宽带化、全球化和个人通信的方向发展。 三、判断题 (对划“√”，错划“╳”) 1、在同一MSC,不同BSC下的切换，系统不需要参和切换过程。（×） 2、使用射频跳频的基站系统，只有在频点大于3个以上时，才有明显效果。（√） 3、跳频可以改善瑞利衰落。（√） 4、移动通信网的信道有控制信道和业务信道两大类。（√） 5、空间分集只能用于基站。（×） 6、扩频系统的抗干扰能力强。（√） 7、IS-95 CDMA是属于第三代通信系统的。（×） 8、在移动通信系统中，相邻小区不允许使用相同频率，否则会产生同频干扰。（×） 9、TDD称为时分双工，收发信号在时间上分开互不干扰，广泛地用于GSM系统。（√） 10、多径效应造成的衰落会随移动台运动速度的加快而加快。（√） 11、3G本身是移动通信网，随着商用化进程的推进，其覆盖范围将遍及几乎所有角落，这样用户的 监控点可以部署在任意位置，不受地域限制。（√） 12、SCH（同步信道）的作用有帧同步和时隙同步。（√） 第一章习题 1、试举出若干个模拟信号与数字信号的例子。 答：模拟信号：语音信号等 数字信号：计算机处理数据等。 2、请说明有线电视、市内电话、调频广播、移动电话、校园网等通信系统各使用哪些信道。答：有线电视：同轴电缆 市内电话：双绞线 调频广播：无线信道 移动电话：无线信道 校园网：双绞线、同轴电缆或光纤 3、试述通信系统的组成。 答：通信系统包括五个组成部分：1）信源；2）发送设备；3）接收设备；4）信宿；5）信道。 4、一个有10个终端的通信网络，如果采用网型网需要用到多少条通信链路？如果采用星型网需要有多少条通信链路？ 答：网状网：45条；星状网：10条 5、试述传码率，传信率，误码率，误信率的定义，单位。并说明二进制和多进制时码元速率和信息速率的相互关系。 答：1）传码率是指单位时间内通信系统传送的码元数目，单位为“波特”或“B”。 2）传信率也称为比特率（bit rate），是指单位时间内通信系统所传送的信息量，单位为“bit/s”或“bps”。 3）误码率就是码元在传输系统中被传错的概率，Pe=传输中的误码/所传输的总码数。 4）误信率是指发生差错的信息量在信息传输总量中所占的比例，Peb=系统传输中出错的比特数/系统传输的总比特数。 r=Rmlog2m（bit/s） 式中，r为传信率，Rm为m进制的传码率。 6、描述点对点通信的几种方式。 答：对于点对点之间的通信，按消息传送的方向与时间，通信方式可分为单工通信、半双工通信及全双工通信三种。 7、线路交换与分组交换的区别在哪里？各有哪些优点？ 答：线路交换：网上的交换设备根据用户的拨号建立一条确定的路径，并且在通信期间保持这条路径，从被呼用户摘机建立通话开始到一方挂机为止，这条线路一直为该用户所占用。线路交换的很大一个优点是实时性好。 分组交换：分组交换是一种存储与转发的交换方式，很适合于数据通信。它将信息分成一系列有限长的数据包，并且每个数据包都有地址，而且序号相连。这些数据包各自独立地经过可能不同的路径到达它们的目的地，然后按照序号重新排列，恢复信息。它的优点是线路利用率高。 8、已知二进制数字信号每个码元占用的时间为1ms，1、0等概率出现，求（1）码元速率，（2）每秒钟的信息量，（3）信息速率。 答：1）码元速率=1/0.001=1000（B） 2）每秒钟信息量=Rmlog2m=1000*1=1000（bit） 3）r=Rmlog2m=1000*1=1000（bit/s） 9、同上题，如果码元速率不变，改用8进制传输，且各码元等概率出现，求码元速率，信息速率。 答：1）码元速率=1/0.001=1000（B） 2）r=Rmlog2m=1000*3=3000（bit/s） 《移动通信技术与设备》课程标准教学大纲教案 一、概述 （一）课程性质 本课程是五年制高职教育层次应用电子技术专业的选修课程，移动通信技术的发展日新月异，作为通信工程专业的学生必须掌握现代移动通信技术的基本概念、基本组成、基本原理、基本技术和典型系统，以适应信息社会对人才的需求。设置本课程的目的是使学生学习了本课程之后，对移动通信的基本概念、基本原理和组网技术有较全面的了解和领会，应能应用移动通信的原理与技术分析阐释常见移动通信方式中信息传输的发送与接收原理，应能分析设计一些简单移动通信系统，为移动通信系统的管理维护、研究和开发打下必要的理论基础和技能。 （二）、课程的基本理念 本课程是五年制高职教育层次应用电子技术专业的选修课程，在教学过程中，主要注重培养学生的专业思维能力和专业实践能力。把创新素质的培养贯穿于教学中，采用行之有效的教学方法，注重发展学生的专业思维、应用能力。 （三）设计思路 本课程充分体现立足行业，强调技能，突出实践，以就业为导向，以能力为本位。以“项目课程”为主体的模块化专业课程体系。 二、课程目标 1、总目标 通过本课程的学习，掌握蜂窝移动通信系统的基本工作原理；熟悉现有的GSM系统和CDMA系统，及2．5代的GPRS系统和CDMA 1X系统；了解3G和未来移动通信系统的技术发展趋势。，使学生具有一定的蜂窝移动通信系统的场强计算、系统设计和网络规 划能力。 2、具体目标 根据课程性质和任务，本课程的主要目标特色在于在具体的任务指导和完成过程中，突出以下知识、技能、态度的培养： 知识目标： 掌握移动通信概念、特点分类； 掌握噪声分类，噪声和干扰对信号传输的影响，干扰的减少。 掌握多址技术，区域覆盖，信道分配，信令，越区切换。 掌握无线寻呼系统的工作原理，无绳电话系统的工作原理。 掌握频分多址（FDMA）模拟蜂窝网系统工作原理、工作过程。 掌握GSM网络接口、GSM系统的无线接口。 能力目标： 学会使用MATLAB软件进行仿真； 情感目标： 具有勤奋学习的态度，严谨求实、创新的工作作风； 具有良好的心理素质和职业道德素质； 具有高度责任心和良好的团队合作精神； 具有一定的科学思维方式和判断分析问题的能力； 三、内容标准 移动通信期中考试题含 答案精编版 MQS system office room 【MQS16H-TTMS2A-MQSS8Q8-MQSH16898】 移动通信期末考试题 一、填空题 1.一个移动通信系统主要的组成部分是移动台、基站、移动交换中心。 2.按通信状态和频率使用方法划分，移动通信系统有单工通信、半双工通信、全双工通信、三种工作方式。 3.我国移动通信网络使用的频段，GSM900MHZ 上行频率890~915MHZ,下行频率 935~960MHZ。DCSI800MHZ上行频率 1710~1785MHZ、下行频率1805~1880MHZ。4.语言编码技术可分为波形编码、参数编码、混合编码技术三类。 5.数字调制技术可分为频移键控调制、相移键控调制、振幅键控调制三类。 6.移动通信中GSM系统采用的是GMSK调制。 7.移动通信的多址技术有频分多址、时分多址、码分多址、空分多址等。 8.根据移动通信网的覆盖方式的不同将移动通信网划分为大区制、小区制。 系统主要由四个子系统组成：交换网络子系统、无线基站子系统、移动台子系统、操作 维护子系统、 系统采用的多址技术是码分多址。 二、选择题 系统的主要使用频段为（D）。 A、900M B、1100M C、1900M D、900M—1100M 2.GSM900MHZ上行频率为（ A）。 A、890—915MHZ B、935—960MHZ C、1710—1785MHZ D、1805—1880MHZ 3.把一个频道按等时间分成周期性帧，再把每一帧分成若干个时的技术是（ B）。 A、频分多址 B、时分多址 C、码分多址 D、空分多址 4.下列哪个系统是“软容量”（ C ）。 A、FDMA系统 B、TDMA系统 C、CDMA系统 D、SDMA系统 5.我国第三代移动通信的标准是（B）。 A、WCDMA B、TD—SCDMA C、 CDMA2000 D、CDMA 6.手机常用电阻5K1的电阻值是（D）。 A、51 B、 C、510 D、 八年级下学期全部长篇课文 Unit 1 3a P6 In ten years , I think I'll be a reporter . I'll live in Shanghai, because I went to Shanfhai last year and fell in love with it. I think it's really a beautiful city . As a reporter, I think I will meet lots of interesting people. I think I'll live in an apartment with my best friends, because I don' like living alone. I'll have pets. I can't have an pets now because my mother hates them, and our apartment is too small . So in ten yers I'll have mny different pets. I might even keep a pet parrot!I'll probably go skating and swimming every day. During the week I'll look smart, and probably will wear a suit. On the weekend , I'll be able to dress more casully. I think I'll go to Hong Kong vacation , and one day I might even visit Australia. P8 Do you think you will have your own robot In some science fiction movies, people in the future have their own robots. These robots are just like humans. They help with the housework and do most unpleasant jobs. Some scientists believe that there will be such robots in the future. However, they agree it may take hundreds of years. Scientist ae now trying to make robots look like people and do the same things as us. Janpanese companies have already made robts walk and dance. This kond of roots will also be fun to watch. But robot scientist James White disagrees. He thinks that it will be difficult fo a robot to do the same rhings as a person. For example, it's easy for a child to wake up and know where he or she is. Mr White thinks that robots won't be able to do this. But other scientists disagree. They think thast robots will be able t walk to people in 25 to 50tars. Robots scientists are not just trying to make robots look like people . For example, there are already robots working in factories . These robots look more like huge arms. They do simple jobs over and over again. People would not like to do such as jobs and would get bored. But robots will never bored. In the futhre, there will be more robots everwhere, and humans will have less work to do. New robots will have different shapes. Some will look like humans, and others might look like snakes. After an earthquake, a snake robot could help look for people under buildings. That may not seem possibe now, but computers, space rockets and even electric toothbrushes seemed 一、单项选择题 1.PN短码用于前向信道的调制，标识不同的________。B A.基站 B.小区 C.业务信道 D.控制信道 2.IS95 CDMA系统中使用的PN短码偏置共有个。A A. 512 B. 1024 C. 32768 D.32767 3.RAKE接收技术是一种_______分集技术。C A. 空间 B. 频率 C. 时间 D.极化 4.IS-95 CDMA移动台最多可以解调______多径信号。C A. 1个 B. 2个 C. 3个 D.4个 5.对于IS95 CDMA系统，寻呼信道数一般为。 A A. 1个 B. 7个 C. 8个 D. 12个 6.反向闭环功率控制比特的发射速率是______。D A. 1bps B. 20bps C.100bps D. 800bps 7.IS95 CDMA同步信道的比特率是。A A. 1200bps B. 2400bps C. 4800bps D.9600bps 8.从WASLH码的角度分析，IS95 CDMA系统的前向业务信道最多有个。B A. 55 B. 61 C. 64 D.48 10. IS95 CDMA小区的PN短码偏置在______信道发布。 A. 导频 B. 寻呼 C. 同步 D.前向业务 二、填空题 1.扩频通信理论中的香农公式为_______。 C=Wlog2（1+S/N） 2.在IS-95 CDMA系统中使用了三种扩频码，分别是_______、________和________。 PN短码、PN长码、WALSH码 3._______在反向信道用于扩频并区分不同的用户。PN长码 4. IS-95 CDMA系统的反向功率控制分为开环功率控制和_______功率控制。闭环 5.CDMA将导频信号分成____导频集、______导频集、_____导频集和剩余导频集。激活、候选、相邻 6.中国电信IS95 CDMA系统的工作频率为：_______(移动台发)，________ (基站发)；频道间隔为_______。825-835MHz 870-880MHz 1.23MHz 7.IS95 CDMA前向信道采用_____阶walsh码进行扩频。 8.IS95 CDMA手机的激活导频集中最多可以有_______个导频。 3 9.IS95 CDMA系统的导频信道使用_______进行扩频，同步信道使用_________进行扩频，寻呼信道使用__________进行扩频。WALSH0 WALSH32 WALSH1-7 10.IS95 CDMA系统业务信道采用________可变速率编码方式。8Kevrc 11. IS95 CDMA系统反向信道由______信道和反向业务信道组成。接入 12.一在通话状态的移动台测量到一个新的导频，其信号强度为-10dB（已知T_ADD=-13dB），此时移动台将申请将该导频加入__________。激活导频集 13. 一在通话状态的移动台测量到其正在使用的一个小区的导频强度为-16dB（已知移动通信技术期末答案
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