NSN考试资料1

liuxuson

1、C1、C2计算

a)   C1=(A-Max(B,0)):

A=Received Level Average – RxLevelAccessMin.

B=MsTxPowerMaxCCH-Maximum RF Power of the MS.

b)    C2 = C1 + cellReselectOffset - temporaryOffset * H(PenaltyTime-T) when PenaltyTime¹640

Where H(x)=1  when T<= PenaltyTime

and H(x)=0  when T> PenaltyTime

or C2 = C1 - cellReselectOffset     when PenaltyTime=640

2、PBGT HO 计算

When the value of parameter EnablePowerBudgetHO is ‘Yes’, the power budget handover is enabled.

After both requirements are fulfilled as the follow, the power budget handover will be triggered.

·         Av_RXLEV_NCELL(n)>rxLevMinCell(n)+Max(0,(msTxPwrMax(n)-msTxPwrMax)).

·         PBGT > hoMarginPBGT(n)

1. PBGT=(msTxPwrMax-Av_RXLEV_DL_HO-(btsTxPwrMax-BTS_TXPWR))-

(msTxPwrMax(n)-AV_RXLEV_NCELL(n)).

3、话务和SDCCH容量计算（包括IUO和双频网的容量计算）

TCH&SDCCH capacity calculated precondition must be known:

· TCH occupation time for one mobile on BH. i.e 1.5 min/call/subs/BH

· Calls number on one cell.  i.e 100 Calls/cell

· SDCCH reservation time for Call establishment.  i.e 7 s/Call

· SDCCH reservation time for SMS.  i.e 2 s/Call

TCH capacity on BH =1.5*100/60=2.5Erl

SDCCH capacity:

· Call establishment (7 s/Call including ciphering and authentication)

=>SDCCH reservation time for Call establishment of a call 7 sec/ 3600sec=1.94mErl

=>100*1.94=0.194Erl/Cell

· Short message service

=>SDCCH reservation time for SMS of a call 2 sec/ 3600sec=0.556mErl

=>100*0.556=0.0556Erl/Cell

· Location updates once in 60 min.

=>100*1.94Erl=0.194Erl/Cell

=>SDCCH Capacity=0.194Erl/Cell+0.0556Erl/Cell+0.194Erl/Cell=0.444Erl/Cell

4、双频网LAC的规划及原因

LAC planning process:

a)   Analysis the handover stats. and customer information.

b)   Find out the best geographical boundary to minimize the location update.

c)   Calculate LAC capacity.

·         SDCCH traffic calculation.

·         Paging Capacity calculation.

·         In term of cells calculation the LA size.

d)   Estimate the growth projection.

e)   Check the feasibility on current BTS/BSC/MSC.

LAC planning Note:

(1) Check the area that has least handover, prevent large amount of subscribers located area.

(2) Preferred the LAC boundary across the road rather than along the main road.

(3) Minimize number of cell that on the boundary.

(4) No umbrella cell or coverage overshooting across different LAC.

(5) Prevent to use CRO at such boundary cell.

(6) Use large value (8dB) as possible for parameter HYS to prevent ping-pong cell reselection.

5、室外的信号在-60dBm,让室内手机守在Indoor信号的参数设置

Defined the microcell(Indoor) cell parameter as the follow:

PI (CELL RESELECTION PARAMETER INDEX)=Y;

REO (CELL RESELECT OFFSET)=30;

TO (TEMPORARY OFFSET)=10;

PET (PENALTY TIME)=20;

6、尽量让微蜂窝多吸收话务量的参数设置

Defined the microcell(Indoor) cell parameter as the follow:

PI (CELL RESELECTION PARAMETER INDEX)=Y;

REO (CELL RESELECT OFFSET)=20;

TO (TEMPORARY OFFSET)=20;

PET (PENALTY TIME)=20;

ENABLE MS DISTANCE PROCESS= Y

ENABLE UMBRELLA HANDOVER = Y

ENABLE FAST AVE HO = Y

Neighbour parameter defined (Macrocell to Microcell):

PMRG=5;

LMRG=-3;

PRI=5;

OF=3;

AUCL=-93;

ACL=LOWER;

FMT=6;

Neighbour parameter defined (Microcell to Macrocell):

PMRG=63;

LMRG=10;

PRI=2;

OF=1;

AUCL=-47;

ACL=UPPER;

FMT=0;

7、切换的类型及radio cause handover

1.Interference Handover (uplink or downlink) ：HO due to interference

2.Quality Handover (uplink or downlink) ：HO due to quality

3.Level Handover (uplink or downlink) ：HO due to level

4.MS-BS distance Handover (maximum or minimum) ：HO due to distance

5.Turn-around-corner MS Handover：HO due to MS turn-around corner

6.Rapid field drop Handover：HO due to rapid field drop

7.Fast/Slow-moving MS Handover：HO due to fast/slow moving

8.Power budget or Umbrella Handover：HO due to power budget or umbrella for better cell

8、Paging information数量的计算

    Paging capacity is related to the number of paging groups, which depends on the frame/channel structure and the parameters noOfMultiframesBetweenPaging and NumberOfBlocksForAccessGrant.

For Combined BCCH:

         i.      IF I reserved 1 block for AG, then I have 2 blocks for PCH.

       ii.      IF I decide TMSI paging, 3 MS can be paged with 1 block of PCH.

Thus,

(number of PCH block*number of pages per block)/(51*one TDMA frame period)

=(2*3)/(51*0.004615)=25

i.e. 34 MS can be paged in a second using TMSI paging. We can get the paging message during busy hour：3600*6/0.235=91915 paging message.

If we reserved 2 paging message to page a MS, then we can calculate how many MS number can page during busy hour：91915/2=45957 mobiles/BH

For Non-Combined BCCH:

      iii.      IF I reserved 3 block for AG, then I have 6 blocks for PCH.

       iv.      IF I decide TMSI paging, 3 MS can be paged with 1 block of PCH.

Thus,

(number of PCH block*number of pages per block)/(51*one TDMA frame period)

=(6*3)/(51*0.004615)=76

i.e. 34 MS can be paged in a second using TMSI paging. We can get the paging message during busy hour： 3600*6*3/0.235=275745 paging message. 40652 62->79

If we reserved 2 paging message to page a MS, then we can calculate how many MS number can page during busy hour：275745/2=137872 mobiles/BH

9、good and bad points for gsm1800 hot spot coverage?

优点:GSM1800实现话务分担

     提高了无线接通率

           降低了掉话

缺点:GSM1800网络瑞利衰落较大,信号不稳定;

GSM1800网络信号对建筑物的穿透能力较弱,容易出现室内盲区;

10、 无线传播模型的应用范围

a)   ＯＫＵＭＵＲＡ－ＨＡＴＡ模型对GSM900频段比较适合;基站天线有效高度为30~200M;移动天线高度为1~10M;通信距离为1~20KM;地形为城区,郊区,开阔地,丘陵,山地,水域

b)   CＯＳＴ－２３１－ＷＡＬＦＩＳＨ－ＩＫＥＧＡＭＩ模型适用频段９００／１８００；移动天线高度为1~10M;通信距离为２~５KM;

11、 decode bcch of service cell 的时间

30s

12、 Handover，BCCH, etc. kinds of information in which system information?

a)   空闲模式下,网络通过BCCH信道传送系统消息1~4及7,8，ＢＣＣＨ信息在系统消息类型２中。ＨＡＮＯＶＥＲ信息在系统消息５中

b)   通话模式下,网络通过SACCH信道传送系统消息5和6

13、 各个信道的作用及分类

  Logical channels are divided into two groups:

l  Common channels are of type point-to-multipoint. All mobiles can overhear them, i.e. they are not specifically addressed to a certain mobile.

l  Dedicated channels are of type point-to-point. They are used for a dedicated and bi-directional communication between the base station and the mobile.

Broadcast Channels (BCH)

Downlink point to multipoint channels. They contain general information about the network and the broadcasting cell. There are three types of broadcast channels:

l  Frequency Correction Channel (FCCH)
acts like a flag for the mobile stations which enables them to find the TRX among several TRXs, which contains the Broadcast transmission.

l  Synchronisation Channel (SCH)
contains the Base Station Identity Code (BSIC) and a reduced TDMA frame number.

l  Broadcast Control Channel (BCCH)
is very important because it contains detailed network and cell specific information such as: frequencies used in the particular cell and neighbour cells, frequency hopping sequence, channel combination, which informs the mobile station about the mapping method used in the particular cell, paging groups and information on neighbour cells. Therefore extra attention should be paid to keep BCCH TRX clean of interference. BCCH is always transmitted on full power. Frequency Hopping or Power Control will never happen on BCCH.

Common Control Channels (CCCH)

Used to set up a point to point connection. There are three types of common control channels:

l  Paging Channel (PCH)
is a downlink channel, which is broadcast by all the BTSs of a Location Area in the case of a mobile terminated call.

l  Access Grant Channel (AGCH)
is the answer to the RACH. It is used to assign a mobile a SDCCH.

l  Random Access Channel (RACH)
is the only uplink and the first point to point channel in the common control channels. It is used by the mobile station in order to initiate a transaction, or as a response to a PCH.

Dedicated Control Channels (DCCH)

Dedicated Control Channels compose the third group of channels. Once again, there are three dedicated channels. They are used for call set-up, sending measurement reports and handover. They are all bi-directional and point to point channels. There are three dedicated control channels:

l  Stand Alone Dedicated Control Channel (SDCCH)
is used for system signalling: call set-up, authentication, location update, and assignment of traffic channels and transmission of short messages.

l  Slow Associated Control Channel (SACCH)
is associated with each SDCCH and Traffic Channel (TCH). It transmits measurement reports and is also used for power control, time alignment and in some cases to transmit short messages.

l  Fast Associated Control Channel (FACCH)
is used when a handover is required. It is mapped onto a TCH, and it replaces 20 ms of speech and therefore it is said to work in "stealing" mode.

Traffic Channels (TCH)

Traffic Channels are logical channels, which transfer user speech or data. They can be either in the form of Half rate traffic (6.5Kbits/s) or Full rate traffic (13Kbits/s).

Downlink direction is from base station towards the mobile.

14、 link budge 计算

上行链路预算=MS pwr+MS ant gain-(BTS sen-BTS ant gain-others UL gains+others UL loss)

下行链路预算=BTS pwr+BTS ant gain-others UL gains+others UL loss-(MS sen –MS ant gain)

         i.      =DL budget-UL budget

       ii.      =0,该链路平衡

      iii.      >0,上行链路预算值为路径损耗

       iv.      <0,下行链路预算值为路径损耗

15、 macro cell 与micro cell handover 的设置

Macro 与 Micro 两个小区之间采用Umbrella handover 方式。优化参数有C2，RXP，PI，REO，AUCL，HPU，GMIC，GMAC

16、      SDCCH的作用

a)   call setup

b)   call reestablishment

c)   location update

d)   emergency calling

17、 有关信道配置方面的参数

1) noOfMultiframesBetweenPaging(2 ... 9) 手机侦听Paging消息的间隔时间，单位为复帧，对应的时间为2*51*4.615 ~ 9*51*4.615 =0.47 ~2.115 s

a)  NumberOfBlocksForAccessGrant (0 ... 7) 定义多少个CCCH块作为AGCH信道

b)  RACH信道配置参数：maxNumberOfRetransmission (1, 2, 4 or 7) 和numberOfSlotsSpreadTrans (3 ... 12, 14, 16, 20, 25, 32, 50)。

NumberOfSlotsSpreadTrans 定义了手机上行发送接入请求消息的窗口；maxNumberOfRetransmission 定义了在窗口范围内最大的重传次数。

4）newEstabCallSupport(Yes/No)和 facchCallSetup (0 ... 4),定义了在呼叫建立阶段是否使用FACCH信道，目前该功能还未使用。

18、 a,abis，ater接口及相关通信信令

1）A 接口:TC和MSC之间的接口，属于开放接口；采用七号信令方式。

2）Abis接口：BTS和BSC之间的接口，属于不开放接口；采用LAPD信令。

3) Ater接口：BSC和TC之间的接口，属于不开放接口；采用七号信令方式。

19、 空间损耗计算

Path loss=(BTS Tx power)-(Combiner loss)-(Feeder loss)+(Gain)-(MS Rx Sensitivity)

Path loss=(MS Tx power)+(Diversity Gain)+(Gain) -(Feed loss)+ (BTS Rx sensitivity)

20、 MOC,MTC, location update and handover calling process

21、 bcch,bsic，c1，c2解码间隔

Mobile Station Measurements in Idle Mode

The Mobile has to decode the BCCH of the serving cell every 30 s, and the BCCH of the adjacent cells every 5 min.

The Mobile also has to pre-synchronise and decode the BSIC of the serving cell once in 30 s.

The list of the Adjacent cells (six best adjacent cells) is updated every 60 s, and if a new cell appears in the list, the Mobile has to decode the BCCH of this new cell in 30 s.

Cell Selection in IDLE Mode, based on C1 or C2，为(btsMeasAver-1) x 480ms

Mobile Station Measurements in Dedicated Mode

In Dedicated mode the Mobile has to pre-synchronise and decode the BSIC of the adjacent cells once in 10 s.

When a new adjacent cell is taken in the list, pre-synchronisation and BSIC decoding has to happen in 5 s.

If it is not successful, the Mobile will use the old neighbour list and again try to decode the BSIC of the new adjacent cell.

22、 measurement processing averaging 计算

The final measurement processing takes place in the BSC, but pre-processing to reduce signalling and processing the load in the BSC is carried out by each BTS.

1)   Pre-processing in BTS

2)   Averaging and Sampling in BSC

3)   DTX and Weighting

4)   Processing in BSC

Averaging and Sampling calculation:

Averaging can be controlled by the parameters ho/pcAveragingLev/QualDL/UL (msDistanceAveragingParam) for handover due to distance, including windowSize (1 ... 32) and weighting (1 ... 3). Parameter weighting tells how samples are averaged and weighted due to the DTX. Averaging is done after each measurement result (after each SACCH period).

Besides above averaging method, there be another new averaging method: Fast Handover Averaging Method (New feature available in S6), there not introduce.

详细介绍可见《BSSpar9.pdf》Page.59(160) -Page.61(160)的9 Measurement Processing

23、 dtx计算

DTX is Discontinuous Transmission. 常用于功率控制；

24、 功率控制原理

When trying to understand the power control algorithm, it should be kept in mind that the whole

process is composed of three steps:

Measurements done by the MS and by the BTS

Measurement processing in the BSC

Threshold comparison

Calculation of the power change

25、 天线类型应用范围

当前我们常用的天线有以下几种类型，第一是65度双极化天线，这种天线一般用于话务量较高的区域，现在主要用在市区；第二是120度单干极化天线，这种天线在一扇区有两根，能更好的保证覆盖，主要用于乡镇或一些话务量较高的农村地区；第三种是360度单极化天线，这种天线一般用于O型站，现在多用于话务量小的农村区域。

26、 双频网络参数优化（切换及重选）

我们通常所说的双频网为900/1800，在双频网络中，一般把900兆当做覆盖层，1800兆做为容量层，因其各自担当的任务不同，所以在参数设置上也有一定的区别，比如，通常状态下，为了让手机在idle模式时驻留在1800网内，可以通过参数rxp,reo,pet,pi,cbq等设置；在通话状态下，一般也尽量让用户切换到1800网内，通常是采取抬高从1800到900的门限，而降低900到1800门限的方法，常的参数有PMRG，LMRG，QMRG等。

27、 antennas coupling and decoupling

   

   

28、 afe 与rtc 区别与应用

AFE和RTC都属于合路器，但AFE只支持将两个TRX的合成，而RTC可以支持最多6个TRX的合成，所以当一个小区的TRX数小于等于4个TRX时，一般用AFE合路器(2个AFE)，而当一个小区的TRX数大于4个时就用RTC。它们之间还有一个重要的区别就是，AFE支支持BB和RF两种跳频模式，但RTC只支持BB跳频。

29、 LAC,Routing area,BSC and MSC间的关系

LAC与ROUting area都是指位置区，但LAC属于GSM范畴，routing area属于GPRS范畴，GSM系统在对手机寻呼时，以一个LAC为寻呼范围，而GPRS则以一个RAC为寻呼范围。BSC与MSC的关系一般是多对一个关系，即一个或多个BSC在一个MSC的控制之下。

30、 DTX is used, what measurement message will be sent to BSC

当DTX使用时，平均电平将由每次测量得到的电平与WEIGHTING和WINDOW SIZE共同决定，所以WEIGHTING，WINDOW SIZE和每次测量的电平值将送到BSC。

31、 The relation between DBD and DBI

dBd和dBi都用来表征天线的增益。DBi是相对于点源天线的增益，在各方向的辐射是均匀的；dBd相对于对称阵子天线的增益dBi=dBd+2.15

32、 Handover power control windows size and related arithmetic

现在POWER CONTROL的WINDOS SIZE 和相关的设置如下：

PC AVERAGING LEV DL       WINDOW SIZE…04  

PC AVERAGING LEV UL       WINDOW SIZE…04

PC AVERAGING QUAL DL    WINDOW SIZE…01

PC AVERAGING QUAL DL    WINDOW SIZE…01  

而HANDOVER WINDOW SIZE为

adjacent cell averaging window size (AWS)…6                                       

   

相关的计算方法还与WEIGHTING和DTX有关，