GSM网规网优技术考评试题

1、GSM网规网优技术考评试题（200703）姓名科室一、不定向选择题（共5题，共40分）下列关于GPRS的说法正确的是（A、B、C ）（A）网络用上行链路状态标志USF控制不同的MS在上行PDCH上复用无线块；（B）对于一个RLC数据块，TBF是由TFI和数据块的发送方向共同标识；（C）支持GPRS的手机主要分为A、B、C三类；（D）多时隙能力等级129，等级数越大，多时隙能力越弱。MSC和SGSN之间的接口称为( C)。（A）Gn（B）Gi（C）Gs（D）GrPhysical Information是在以下哪个过程中被用到？（D ）（A）MOC（B）MTC（C）同步切换（D）异步切换如果某一公

2、路旁边有一定向站，采用垂直线极化定向天线，空间分集接受，请问两个天线的连线和公路成什么角度最合理？（ B）（A）00（B）900（C）450（D）300（5）下列说法正确的是（B、C、D）（A）在GPRS系统消息3中传送有关参考频率列表、PRACH控制参数、PCCCH描述等；（B）当一个PDCH不是PCCCH时，8个USF值都被用于为8个不同的MS预约上行链路；（C）关于无线链路控制及媒体访问控制协议的内容在GSM04.60有详细描述；( D)BSSGP层传送BSS和SGSN之间的路由相关和Qos相关信息，不执行纠错。二、简述题（共4题，共60分）（1）请简述GPRS附着成功率低的常见原因以及

3、解决办法？ANS：（出题原则：逐步培养分析和解决GPRS网络问题的能力）常见原因：用户故障的原因 手机不支持GPRS或没有开通GPRS业务 手机和网络的设备不兼容 手机的访问权限受限 小区重选过于频繁，导致附着不稳定或附着不及时网络故障 网络没有开通GPRS业务 网络没有分配GPRS资源，或GPRS资源不足 信令数据传输出现问题 无线环境覆盖弱 小区存在同邻频干扰或外部干扰 小区拥塞，附着请求得不到及时响应 系统繁忙或响应缓慢，影响登记速度解决办法： 关闭SGSN鉴权； 采用一步接入方式； 检查覆盖； 防止频繁的小区重选； 排查干扰，提高C/I； 检查RACH或AGCH信道配置； 检查GPRS

4、 ENABLED参数设置； 检查Gb links load，调整NSEI配置； GPRS核心网调整。（2）简述如何通过OMCR性能统计功能来分析和定位一个小区的掉话？ANS：（出题原则：主要考察各种性能报表和测量报表对掉话的定位和分析作用）OMCR对于TCH的掉话主要分为：无线链路失败掉话、切换失败掉话、LAPD掉话从OMCR后台提取小区级性能报表，分析小区性能指标，确定高掉话小区的掉话原因；提取各种测量报表，确定小区的掉话类型、定位，针对掉话的不同原因和类型，分析下述的各种测量任务报表，来分析和解决掉话问题：小区性能报表：分析TCH指配、拥塞、切换、掉话等情况；CS基本业务测量：对小区性能进

5、行全面的统计分析，包括掉话类型、干扰带、TCH指配、上下行质量统计等；RMM掉话测量：描述了信令流程中各类信道、业务上RMM掉话的次数、引发掉话的原因等数据，用以了解网络运行状况、评测网络性能、调整网络参数等；BTS测量：定位载频级的掉话和指配失败、干扰带等；小区无线测量：小区无线测量，分析小区的电平与质量分布；切换统计测量：针对各种切换原因导致的切换过程进行统计，包括尝试、执行、成功、失败的次数，反映出切换的成功率；NMS测量：TCH信道占用时长短；切换原因测量：分析各种切换原因及其比例；功率控制性能测量：平均上、下行信号强度情况；TRX LAPD链路测量任务；统计连接每个TRX 的LAPD

6、信令链路上的信令交互情况，由LAPD板在发送和接收消息时统计；针对掉话类型进行针对性的分析处理。（3）简述T3168和T3192定时器的含义及其设置大小对网络的影响？ANS：（出题原则：对GPRS常用定时器的掌握）T3168：描述：手机侧使用参数。属于GPRS小区选项参数，在PSI1、PSI13和SI13消息中广播给手机，指明MS在发送PACKET RESOURCE REQUEST（或者PACKET DOWNLINK ACK/NACK消息里带Channel Request Description IE时）消息后等待PACKET UPLINK ASSIGNMENT消息的最长时间。取值范围：取值代

7、表的时间长度00.5秒11.0秒21.5秒74.0秒默认值：7（4.0秒），一般可以取12s。设置大小对网络的影响：T3168设置的大小影响TBF建立成功率的高低，该值取值越小，则给与TBF建立的时间就越短，在无线环境恶劣的情况下，TBF的建立成功率就越低；反之，该值设置越大，MS判断发生TBF建立失败的周期就越长，TBF的建立成功率会在一定程度上提高，但是以延长接入时长为代价，导致系统获得的整体性能降低。 该值的设置必须考虑到无线环境的影响，一般以BLER的好坏为参考依据：BLER2%，即无线环境很好时，T3168可设置为0.5s； 2%BLER5%,无线环境较好时，T3168可设置为1s；

8、 5BLER10%,无线环境恶劣时，T3168可设置为2sT3192：描述：手机侧使用参数。在分组下行传输过程中，若待发RLC数据块是最后一下行数据块，网络将通过发送一个最后块标识（FBI）域为“1”且包含一个有效RRBP域的RLC数据块来初始化下行TBF的释放。对于每个收到的FBI为“1”且包含有效RRBP域RLC数据块， = 1 * GB3 若确认模式下，MS应在由RRBP域指定的上行块上发送FAI域为“1”的“分组下行确认/否认”消息； = 2 * GB3 若非确认模式下，MS应在由RRBP域指定的上行块上发送“分组控制确认”消息。这时手机启动T3192定时器。T3192超时后就释放资源

9、、停止侦听PDCCH信道，并转到寻呼信道侦听。手机在T3192定时器保护期内，若收到网络侧来的PACKET DOWNLINK ASSIGNMENT消息或PACKET TIMESLOT RECONFIGURE消息，则T3192定时器停止，并转入分组传输态。取值范围：取值代表的时间长度（单位：ms)0500110002150030480512061607200默认设置：0（500ms）。T3192代表的时间长度必须小于网络侧下行TBF的保护时间T3193，以确保MS在同一时刻TFI的唯一。设置大小对网络的影响：定时器T3192用来设定MS在完成接收最后一个数据块后，等待TBF释放的时间。在TBF释

10、放阶段，如果MS处于ready状态并且收到上行指配，MS将立即响应该命令；如果在TBF释放阶段没有收到上行指配，MS将进入分组空闲模式。在进入空闲模式时，由DrxTimeMax定时器决定MS停留在非DRX的时长。 该参数设置越大，TBF相关资源保留（包括TFI和时隙）的时间就越长，相同TBF传送占用的时间就越长，容易导致资源的浪费。该参数设置越小，TBF资源的释放时间将变短，此时若新的下行数据，网络必须发起寻呼或立即指配流程（就绪状态），则下行TBF建立的时间就越长。而如果网络侧新的下行数据到来时，T3192还未超时，则网络可以直接发送“分组下行指配”消息，来建立一个新的下行TBF，缩短TBF

11、的建立时间。该参数设置的大小，需要考虑小区的数据业务负荷大小、小区的数据业务模型，在PDCH信道子资源宽裕的情况下，T3192可以设置的大些，以尽快减少TBF的建立时间，提高数据传输速率。（4）请V3宏基站产品相对比V2宏基站产品而言具有的优势？ANS：V3 设备是公司新开发的产品，相对于V2产品有了很大的改进。主要产品8000系列基站的B8018、B8112等系列基站产品，在系统设计和系统性能上拥有很多的优势和进步：概括性优点：双载波、大容量、多分集、动态Abis、智能上下电大容量（B8018）：单机架满配18个载频，9个DTRU，单机柜最大支持的站型为S6/6/6。支持同一站点54个载频扩

12、展，一个站点支持S18/18/18的扩展。支持多种类分集技术支持上行链路干扰抑制合并IRC（Interference Rejection Combining）分集技术可以认为是一种更高级的分集接收功能，它可以改善上行的质量，提高上行的增益。IRC分集接收方式，可以提高接收机的上行灵敏度指标，增大基站上行的覆盖范围。支持下行延时分集发射DDT（Delay Diversity Transmission）下行延时发射分集的原理是基于基站主、分集信号到达手机天线信号衰落的不相干性原理，即两路发射到手机天线的信号，同时出现幅度谷点的概率相当小。两个发信机在短时延内发射相同信号，两个发信机当作一个“虚拟发

13、信机”来使用，使下行信号增强，可以获得3dB的下行增益，从而提高了覆盖范围，能够实现20%（甚至30%）以上的增强覆盖。支持4路分集接收（FWDR）基站可以提供一个载波的4路分集接收信号，获得最佳的增益。增强基站上行链路的接收性能的同时，还可降低MS的发射功率，4路分集功能和延时发射分集同时使用，可使基站实现超远覆盖。利用从四条不同路径来的上行信号，通过合并形成最终更好的接收信号，四路信号要求来自4根不同的天线。由于信号通过更多的路径到达收发信机，因此，此功能可以增强上行链路预算，即提高基站的接收灵敏度。动态ABis接口支持IP 接口，BSC与BTS之间的数据格式以IP包的形式传输，链路承载使

14、用以太网的形式传输，利用IP网络的高带宽特性，实现网络的快速扩容。提高带宽利用率，降低CAPEX。Abis接口支持8路E1/T1接口（B8018和B8112）。双载波支持DTRU（Dual-carrier TRU）DTRU单元是B8018,B8112的核心模块，每个物理载频模块内含两个收发信机。主要完成GSM系统中两路载波的无线信道的控制和处理、无线信道数据的发送与接收、基带信号在无线载波上的调制和解调、无线载波的发送与接收等功能。具有如下特点：集成度高，设备性能得到整体提高；提高生产效率，缩短供货周期降低运输成本，降低安装难度；支持DPCT（Dual Power Combining Tran

15、smission）方式的扩展覆盖BTS的双密度载频模块中的两个发信机实现相干联合DPCT。即模块中的两个发射机在同一时刻发出同样的突发脉冲，通过合路器，构成形式上的一个载波，从而得到大约2.5dB的下行发射增益，扩大了小区的覆盖范围。4路分集功能和DPCT同时使用，可使基站实现超远覆盖。智能上/下电由于在一些情况下，单板可能处于无法监控的状态，或者硬件上的复位无效，以及系统需要进行关电、省电模式，可以通过系统控制的单板（CMB）关掉一些单板（DTRU）的供电。例如，在正常供电时，系统能根据话务量的下降适当关闭部分载频模块的电源。III简答题Questions请简述对T3212参数的设置的注意事

16、项。Please describe the precautions on setting of T3212 parameter. 答：t3212是周期性位置更新时间参数，用来强制移动台在该定时器逾时后自动向网络发起位置更新请求。T3212越小，网络的总体性能就越好，但频繁的位置更新有两个负作用：一是会使网络的信令流量大大增加，对无线资源的利用率降低。在严重时将影响MSCBSCBTS的处理能力；另一方面将是移动台的耗电量急剧增加，使该系统中移动台的待机时间大大缩短。还有一点要注意的是，T3212必须小于NSS内部设置的隐含关机时间，以防止由于移动台没有及时进行位置更新而和网络失去联系。Answe

17、r: t3212 is the periodic location update time parameter that is used to force the mobile station to initiate a location update request to the network after this timer expires. The smaller value of T3212 indicates the better overall performance of the network. However, the frequent location update ha

18、s two side effects. One is the signaling flow of the network will increase substantially, so the utilization of radio resources decreases. In the worst case, this will negatively affect the processing capability of MSCBSCBTS. The other is the mobile station has a rapidly increased power consumption,

19、 so the standby time of the mobile station in this system reduced greatly. Also note that T3212 must be less than the implicit shutdown time set within NSS, so as to prevent the mobile station from failing to connect to the network because it does not conduct location update timely. 请简述几种消除同频道干扰的方法。

20、Please describe several methods for eliminating the co-channel interference. 答：增加两个同频道小区的间距。Answer: Increase the distance between two cells with the same channel. 降低基站和MS的发射功率电平来避免同频干扰。Reduce the transmitter power levels of the base station and MS to prevent co-channel interference. 不连续发射（DTX）。Disco

21、ntinuous transmission (DTX). 降低基站天线高度。Lower the antenna of base station. 更改天线的安装位置或者天线方向偏移。Install the antenna to another place or change the offset of antenna direction. 3.请简述容量规划过程。Please describe the capacity planning process. 估算容量受限区域所需基站总数、站型和容量：Estimate the total of base stations, station type

22、 and capacity for the area where the capacity is limited: 由频率资源及频率复用方式，估算每个基站最大站型和容量；Estimate the largest station type and capacity based on the frequency resources and frequency reuse pattern. 总话务量除以基站最大容量(各小区之和)，可得出所需基站总数；The total of base stations can be obtained by dividing the total traffic by

23、the maximum capacity of base stations (total of capacities of all the cells). 由话务模型、爱尔兰B表，得到话音信道数、控制信道数和容量。The number of voice channels, the number of control channels and the capacity can be obtained using the traffic model and the Erlang B table. 估算覆盖受限区域所需基站总数、站型和容量：Estimate the total of base sta

24、tions, station type and capacity for the area where the coverage is limited: 用规划区面积除以基站最小覆盖面积（估算）得到基站总数；Divide the area of planned region by the minimum coverage (estimated) of the base station to get the total of base stations. 小区覆盖面积（估算）乘以相应的话务密度，得到该小区目前需满足的话务量；Multiply the cell coverage (estimate

25、d) by the corresponding the traffic density to obtain the traffic of this cell that should be satisfied. 查爱尔兰B表，估算所需的话音信道数和控制信道数；Check the Erlang B table and estimate the number of voice channels and the number of control channels. 两者相加除以8得出该基站该小区所需载频。Divide the sum of the two numbers by 8 to obtain

26、 the carrier frequencies required for the cell of the base station. 根据覆盖确定需要的BTS数，根据用户容量确定需要的BTS数量，两者之间取大者Determine the number of required BTSs according to the coverage, and determine the number of required BTSs according to the subscriber capacity. The larger one of the two numbers should be used.

27、 简答题Questions频率复用的定义，常用的几种频率复用方式？Describe the definition of frequency reuse and list the several common frequency reuse modes. 答：频率复用就是指在数字蜂窝系统中重复使用相同的频率，一般把有限的频率分成若干组，依次形成一簇频率分配给相邻小区使用。频率规划的基础工作就是频率复用。常用的频率复用方式有7*3、4*3、3*3、1*3。Answer: Frequency reuse means the same frequency is reused in the digita

28、l cellular system. Generally, limited frequencies are divided into several groups to form a cluster of frequencies that can be allocated to the adjacent cells for use. Frequency reuse is the basic job of frequency planning. The common frequency reuse modes include 7*3, 4*3, 3*3 and 1*3. 请简述GSM系统的基本信

29、道分类Please describe the basic channel types of the GSM system. 答：GSM系统中，信道分成物理信道和逻辑信道，时隙是基本的物理信道，即一个载频包含8个物理信道。无线子系统的物理信道支撑着逻辑信道。逻辑信道按其功能分为业务信道（TCH）和控制信道（CCH）。其中控制信道用于携载信令或同步数据，包括三类控制信道：广播信道、公共控制信道和专用控制信道。Answer: In the GSM system, channels can be divided into physical channel and logical channel. Ti

30、meslot is a basic physical channel, namely one carrier frequency contains eight physical channels. The physical channel of the radio subsystem bears the logical channel. Logical channels can be divided into Traffic Channel (TCH) and Control Channel (CCH) by function. The control channel is used to c

31、arry the signaling or synchronize data. There are three types of control channel: broadcast channel, common control channel and dedicated control channel. 请简述GSM系统跳频的意义Please describe the meaning of frequency hopping in the GSM system. 答：在蜂窝移动通信系统中应用，可以提高系统抗多径衰落的能力，并且能抑制同频干扰对通信质量的影响，跳频主要带来的好处是所谓频率分集

32、(Frequency Diversity)和干扰分集(Interference Diversity)的效果。频率分集实际上是提高了网络的覆盖范围，干扰分集则提高了网络的容量。Answer: This function can be used in the cellular mobile communication system to improve the ability of the system to prevent multipath fading and reduce the influence of co-frequency interference on the communica

33、tion quality. The benefits of frequency hopping are the effects of frequency diversity and interference diversity. The frequency diversity extends the network coverage, while the interference diversity increases the network capacity. 画出无线网络建设的示意框图Draw the schematic diagram of radio network construct

34、ion. 请简述规划中上下行链路功率平衡预算的主要目的是什么？Please describe the major purposes of power balance budget for the uplink and downlink during the planning. 答：上下行链路功率平衡预算通过调整基站的发射功率，使得覆盖区边界上的点下行接收信号扣除损耗及系统裕量后大于手机接收灵敏度，而该点上行信号到达基站后扣除损耗及系统裕量大于基站接收灵敏度。目的是保证设计系统满足覆盖要求。降低可能的因为上下行链路不平衡引起的单向通话、提高有效的无线接通率。也就是准确的上下行链路功率平衡预算是保

35、证在两个方向上具有同等的话务量和通信质量的手段，也关系到小区的实际覆盖范围。Answer: The power balance budget for uplink and downlink makes, through adjustment of transmitter power of base station, the received downlink signal at the point on the edge of coverage to be larger than the receiver sensitivity of mobile phone after deducting

36、the loss and system allowance; and makes the uplink signal of this point that arrives the base station to be larger than the receiver sensitivity of base station after deducting the loss and system allowance. It aims to make sure that the system is designed to satisfy the coverage requirements, redu

37、ce the possible unidirectional communication due to imbalanced uplink/downlink, and increase the effective wireless call completion rate. In other words, an accurate uplink/downlink power balance budget is used to ensure two directions have the same traffic and communication quality. It is also rela

38、ted to the actual coverage of a cell.交换机局数据检查主要包括那些项目：Please describe the items that should be checked for the exchange data of switch. 答：主要包括本系统内处理机的配置、中继群、中继电路的定义及配置、对端局类型、所采用的信令类型等。基站的数量、每个基站无线信道的数量。寻呼区的定义、本系统的用户数量等。Answer: Such items include configuration of processor within this system, definit

39、ions and configuration of trunk group and trunk circuit, type of the opposite exchange, the signaling type in use, quantity of base stations, quantity of radio channels of each base station, definition of paging area, quantity of subscribers of this system, etc. 小区全球识别码的组成What does the cell global i

40、dentity consist of? 答：MCC+MNC+LAC+CIAnswer: MCC+MNC+LAC+CIGSM系统中发生位置更新的原因Please explain the causes for location update in the GSM system. 答：主要有两类，一种是移动台发现其所在的位置区发生变化（LAC不同）；另一种是网络规定移动台周期地进行位置更新。周期位置更新的频度是由网络控制的，周期长度由参数T3212确定。Answer: In the GSM system, there are two causes for location update. First

41、, the mobile station finds the location area where it resides in changes (with a different LAC). Second, the network requires the mobile station to update its location periodically. The frequency of periodic location update depends on the network, and the length of period is depends on the parameter

42、 T3212. 1.移动公司反映部分基站有覆盖下降的现象，导致用户投诉，试分析出现覆盖下降的可能原因Staff from China Mobile reflects that some of the base stations suffer reduced coverage, which causes complaints from subscribers. Please analyze the possible causes for reduced coverage. 案：接入参数调整：如TA值限制，最小接入电平限制，随机接入错误门限过高；Answer: Adjustment of acce

43、ss parameters, such as limit of TA value, limit of minimum access level, and excessively high random access error threshold. 频率规划调整引入的干扰，导致小区在被干扰的方向上覆盖缩小；The adjustment of frequency planning introduces interference that results in reduced coverage in the interfered direction of the cell. 网络配置参数不全，不能

44、及时切换/重选，造成覆盖缩小的假象；The network configuration parameters are not complete and thus the handover/reselection cannot be conducted timely, giving the false impression of reduced coverage. 天线方向角、下倾角变化，服务范围发生变化，导致原来覆盖好的地方覆盖不好；或两根全向天线都发射时，不同载频覆盖范围不一致Change of antenna direction angle and tilt angle, and chan

45、ge of service scope results in poor coverage in the places where it was under proper coverage originally. Different carrier frequencies have inconsistent coverage when both the omni-directional antennas transmit. 基站设备扩容引入新的插入损耗，导致服务小区半径缩小Equipment expansion for the base station introduces new insert

46、ion loss, which reduces the radius of the serving cell. 基站硬件故障没有及时处理，如载频板故障（1分）The hardware failure of base station, such as failure of the carrier frequency board, is not handled timely. (1 point)扩容不及时，引起服务质量不好，导致用户投诉覆盖下降；The base station is not expanded timely and has a deteriorated QoS, which cau

47、ses complaints from subscribers on reduced coverage. 原来覆盖就不好，由于用户的普及，引起投诉，给人以覆盖下降的假象；The original coverage is not good enough and causes complaints when there is an increasing number of subscribers, giving the false impression of reduced coverage. 服务区的边缘，由于小区参数设置修改造成不能打电话，引起投诉；Calls cannot be placed

48、 at the edge of serving cell because the setting of cell parameters has been modified, which causes complaints. 天馈驻波比过大，造成发射功率下降。The antenna feeder has a too large standing wave ratio, which reduces the transmitter power. 1.掉话率在移动通信网中是一项非常重要的指标，掉话率的高低在一定程度上体现了移动通信网络的优劣。请简要分析引起掉话的原因和提出解决方案Dropped cal

49、l rate is a crucial index in the mobile communication network. Its value reflects the quality of the mobile communication network to a certain extent. Please analyze the causes for call dropping and provide a solution. 答：引起掉话的原因主要可能有如下几个方面：Answer: Call dropping may be caused by: 盖不良。孤岛站比较明显。Poor cov

50、erage. The base station is separated like an island. 在干扰。同频干扰或者是邻频干扰都可能引起掉话。Interferences. Either the co-frequency interference or adjacent frequency interference may cause call dropping. 由于切换而引起的掉话。切换参数设置错误或者不良都可能引起掉话。Handover. The call dropping may occur when the handover parameters are set wrongl

51、y. 系统性能不良引起的掉话。硬件故障，天馈线原因引起掉话。Poor performance of the system. The call dropping may occur when the hardware fails or there is a problem with the antenna feeder. 解决方案：Solution: 减少掉话的措施要具体问题具体分析，一般来讲，OMC-R运行维护软件中都会有各小区的分时段的掉话统计报告,再结合用户的投诉,我们可以初步确定掉话的重点地区。The measures for reducing dropped call rate sho

52、uld be based on the actual cases. Generally, the areas that suffer call dropping can be identified using the dropped call statistics report for each period of time for each cell provided by the OMC-R operation & maintenance software and complaints from subscribers. 在通常情况下，我们应当首先检查掉话率较高的小区的基站硬件设备是否有问

53、题。包括检查掉话现象增多时的时间，以及设备的运行中的告警和通知消息报告。并且和此小区的其他性能指标在一起进行综合分析。比如，如果此小区的TCH指派成功率也较低的话，我们将考虑是否此小区的收发信机有什么问题或者天线未能正确安装(两个小区的天线装反了)，某段馈线或接头处未能完成良好的屏蔽等。Typically, we should first check whether there is a problem with the hardware equipment of base stations in the cell with high dropped call rate. Check the

54、period of time when there are more dropped calls and check the alarm and notification message reports during equipment operation. Also make a comprehensive analysis on the above items and other performance indexes of the cell. For example, if this cell has a low TCH allocation success rate, we can c

55、heck whether there is a problem with the transceiver of this cell, whether the antenna is not installed properly (the antennas of two cells are installed wrongly), or whether the feeder or connector is not shielded properly. 其次，应当考察此小区是否受到干扰，一般在基站的话务统计报告中，基站会将自己对各载频频点的干扰报告传送到OMC-R。如果从报告中可以得出本小区受到干扰的

56、结论，那么，下面要作的工作是检查频率规划的方案，看看频率规划中是否错误地将相邻小区的频点设为本小区的同频或邻频，或者在实际的频率配置操作中有所失误。Second, we should check whether this cell is interfered. Generally, the base station will send its interference report on each carrier frequency point to OMC-R among the traffic statistics reports. If a conclusion can be made

57、from the report that this cell is interfered, then check the frequency planning scheme to see whether the frequency of the adjacent cell is set to the same or the adjacent frequency of this cell, or whether the frequency is configured incorrectly. 对于覆盖不良而引起的掉话，我们可以通过路测来发现和解决。增大基站的覆盖范围（如提高基站的最大发射功率或者

58、改变天线的方位角、倾角和挂高等）。For the call dropping due to poor coverage, we can locate and solve the problem by conducting the drive test. Extend the coverage of the base station (such as increase the maximum transmitter power of the base station, or change the direction angle, tilt angle and height of the ante

59、nna). 对于切换造成的掉话，检查网络参数，看有没有设置不合理的地方，比如邻小区定义错误，切换门限设置不合理等等。For the call dropping due to handover, check whether the network parameters are set unreasonably, such as wrong definition of adjacent cell and unreasonable setting of threshold. 2.请简要的谈谈双频网络的话务分担如何实现。Please explain how to implement the traff

60、ic sharing for the dual-band network. 答：900M主要实现覆盖，而1800M主要实现话务的分担。所以我们尽量要使网络用户占用到1800M上面来。Answer: 900M provides coverage, while 1800M implements traffic sharing. We should make every endeavor to let subscribers to use 1800M. 参数方案举例和说明：Example and description of parameter scheme: 空闲模式：Idle mode:900M