GO_NA10_E1_1 GSM Dual-Band Network Planning & Optimization

GSM Dual-band Network Planning & Optimization

ZTE university

Objective

� After completing this course, you will be able to:� Know the background of the introduction of dual-band

network� Know network construction and advantages of dual-

band networkband network� Know the planning strategy of dual-band network� Know the definition of radio parameter and optimizing

strategy of dual-band network

Catalog

� Dual-band Overview� Dual-band Network Planning Strategy� Dual-band Network Optimization Parameter

Tuning� Dual-band Network Optimization Cases

Dual-band Overview

� Background of Dual-band Network� The earliest GSM digit mobile telecom network is 900M.

With the rapid growth of the users, demand of network capacity is increasing tremendously. So limitation of frequency resource and lack of radio channel capacity become choke point of network development.point of network development.

� GSM1800(DL：1805～1880MHz UL：1710～1785MHz) network is introduced and GSM900/GSM1800 dual-band network construction can satisfy demand for GSM network capacity.

Dual-band Network Overview

� advantages of DCS1800� Make up for GSM900 frequency resource shortage.� GSM 1800 is similar with GSM900 in Network

construction, engineering, network planning , and network maintenance and service

� Share GSM 900 sites so as to save the construction cost

� GSM terminals supporting dual-band are nowbeing popularized.

Dual-band Network Overview

� Features of dual-band network� GSM900M and DCS1800M can be adjacent cells of

each other.� These two serial of cells can be handed over and be

reselected.

GSM900

GSM1800 GSM1800

GSM900

＋＝

Similarities & Difference between GSM900 and DCS1800

� same network construction

� same voice coding� same modulating technology� same signaling procedure

� different spectrum amplitude� different radio propagation� different coverage scope� different output power

� same frequency planning tool

D u a l-band Network Construction

� Network construction of GSM1800 and GSM900� Independent network constructing mode in different MSC� Mixed constructing mode in one MSC� Mixed constructing mode sharing one BSC� Mixed constructing mode sharing one BTS� Mixed constructing mode sharing one BTS

Independent Network Construction Mode

� Features� GSM1800 and GSM900 have different BSC and MSC，sharing

one HLR, AUC and OMC etc.� 900M cell and 1800M cell in the same physical area belong to

different location area, and MS in these two network systems will arouse multiple location area upgrading.

Mixed Network Construction Mode Sharing MSC

� Features� GSM 1800 and GSM 900 share MSC/VLR, HLR/AUC and OMC etc.

BSS of GSM1800 and of GSM900 are connected to MSC/VLR via A interface.

� GSM 1800 shall be the major part with the support of DCS1800 in dual-band network. GSM900 realizes favorable and full coverage and GSM1800 provides dense area with supplementary capacity.and GSM1800 provides dense area with supplementary capacity.

Mixed Network Constructing Mode Sharing BSC

� Features� BSS equipment of GSM1800 and GSM900 should be from the

same manufacturer when Abid interface is unopened. � Shared BSC should support dual-band network with the equipment

coming from the same manufacturer, which can utilize the existing BSC and MSC equipment for money saving purpose.

Mixed Network Constructing Mode Sharing BTS

� Features� Transceiving are encouraged in GSM900 and GSM1800 sharing

one BTS. BTS should support collocated-BCCH.� This network constructing mode is cost-saving and easy to conduct

and exiting network facilities can be utilized.

Contrast of Different Network Constructing Mode

� The following is contrast of three typical dual-band network constructing mode from technology and economics prospective.

dual-band network

dual -band impact on GSM900 by network

constructing mode

dual -band handover speed & signaling

impact on GSM900 by the project

investment

IndependentMSC

slow/great little great

share MSC moderate moderate moderate

share BSC fast/little Great little

Network Constructing Mode Recommended

Network constructing mode

(be careful)

� Independent MSC

原因分析原因分析原因分析原因分析Prior network constructing

mode

� Sharing BSC

� Sharing MSC

Advantages of mode sharing BSC and mode sharing MSC

compared to mode MSC independent

� Handover is easy to carry out and amount of signali ng needed

to be handled is small while result comes out good .

� Sharing MSC

Catalog

� Dual-band Overview� Dual-band Network Planning Strategy� Dual-band Network Optimization Parameter

Tuning� Dual-band Network Optimization Cases

Dual-band Network Planning Principles

� Planning Principle� GSM900 shall be the major part with the support of

DCS1800 in dual-band network. GSM900 realizes favorable and full coverage and GSM1800 provides supplement capacity for dense area.

1800M coverage GSM900Mcoverage

GSM900M MS

GSM dual-band MS

Dual-band Network Coverage Mode

� Initial stage: hotspot� Middle stage: small-coverage area� Later stage: continuous coverage

continuous coveragecontinuous coveragecontinuous coveragecontinuous coverageDCS 1800 sitesDCS 1800 sitesDCS 1800 sitesDCS 1800 sites

NonNonNonNon----continuous continuous continuous continuous coverage DCS1800 coverage DCS1800 coverage DCS1800 coverage DCS1800 sitesitesitesite

GSM 900 sitesGSM 900 sitesGSM 900 sitesGSM 900 sites

GSM900 layer Handover due to coverage � only solve the short-term capacity shortage

� Signalling load


� Hotpot and small-coverage area

GSM1800 hotspot Inter-band handover due to capacity

� Signalling load increases due to frequent handover , which results in capacity loss.


� Principle of collocated BCCH : GSM900 and GSM1800 exists in one cell. BCCH and SDCCH channel are configured on 900M frequency. Non-BCCH frequency can be 900M or 1800M.

� Advantage: save one BCCH TSL as well as � Advantage: save one BCCH TSL as well as expanding the capacity (biggest advantage). Configure 1800 carrier in 900M cell. Neighboring relations of the cells need not to be changed, network needn’t to be planned again and dual-band cell reselection and handover needn’t to be considered again.

GSM900 layer Inter-band handover due to coverage

�Easy for expansion, and is a solution to long-term capacity�Compared to hotpot coverage, signalling load


� Continuous and large scale coverage

GSM1800 layer inter-band handover due to capacity

coverage, signalling load reduces greatly, as a result, capacity increases.

DCS1800 Project Construction

� DCS1800 sites distribution� We suggest to select sites already in GSM900 system and use site

equipment room, iron tower, power supply facilities, and transmit devices in the sites for cost-saving purpose.

� Antenna installation� Antenna installation� It’ s best that antenna of DCS1800 is 2-3m higher than that of

GSM900� Antenna direction of the two should be the same for traffic control� Half-power angle of both horizontal and vertical direction should be

small and similar (pattern).� DCS1800 main-lobe gain is greater than or the same with 2-5dBi.

DCS1800 Site Distance

� Difference between propagation loss of 1800M and of 900M� Macro-cell (radius>3 Km )

� Path loss of 1800MHz is 12.8dB greater than that of 900MHz

� Micro-cell (Radius<3 Km)� Path loss of 1800MHz is 6dB greater than that of 900MHz

� Indoor loss� Path loss of 1800MHz is 12-17dB

900M

1800M

� Penetration loss

DCS1800 Distance

1800M

Distances between DCS1800 Sites

� Suggestions� It’s possible that when average distance between sites

is 500-800 m, GSM1800 system can provide with favourable both indoor and outdoor coverage.

� Boosting antenna gain, site transmission power and site reception sensitivity can add to GSM1800 coverage.

� Some site’s traffic is high but the distance is much far. In this case, site need to be added and its power capacity shall base on coverage and quality.

Catalog

� Dual-band Network Overview� Dual-band Network Planning Strategy� Dual-band Network Optimization Parameter

Adjustment� Dual-band Network Optimization Cases

MSC

Paging establishment and sending CM3

Dual-band Network Optimization Parameter Adjustment

� Switch can provide with handling Class Mark 3 ( CM3 ) message function

GSM900BTS

DCS 1800BTS

BSC BSC

and sending CM3 message during handover

Class Mark3Power GSM 900 DCS 1800 Tolerance (dB)

class Nominal Maximum output

Nominal Maximum output

for conditions

power power normal extreme

1 - - - - - - 1 W (30 dBm) ±2 ±2.5

2 8 W (39 dBm) 0.25 W (24 dBm) ±2 ±2.5

3 5 W (37 dBm) 4 W (36 dBm) ±2 ±2.5

4 2 W (33 dBm) ±2 ±2.5

5 0.8 W (29 dBm) ±2 ±2.5

NOTE: The lowest nominal output power for all classes of GSM 900 MS is 5 dBm and for all classes of DCS 1800 MS is 0 dBm.

Cell Selection

� Cell Selection� When MS powers on or enters from blind spot to

coverage spot, MS monitors cell signaling and synchronizes with the cell, scan BCCH of cells and select appropriate cells to stand according to cell priority and C1>0 criterion.and C1>0 criterion.

According to cell priority and C1 value to select standing cell, According to cell priority and C1 value to select standing cell, According to cell priority and C1 value to select standing cell, According to cell priority and C1 value to select standing cell, i.e. serving cell.i.e. serving cell.i.e. serving cell.i.e. serving cell.

� C1 is cell path loss judge criterion para.�C1 = (A-Max(B,0))

�A=RXLEVEL－DL-RXLEV_ACCESS_MIN

�B = MS _TXPWR_MAX - P

�RXLEVEL is average level received by MS

C1 Criterion

�RXLEVEL is average level received by MS

�DL-RXLEV_ACCESS_MIN is allowable minimum level received by MS

�MS_TXPWR_MAX is maximum power level of control channel

�P：MS maximum output level

CBA、CBQ

CellBarQualify

CellBarAccess

Cell Select priority

Cell Reselect Status

0 0 Normal Normal

0 1 Barred Barred

1 0 Low Normal

1 1 Low Normal

Cell Selection

� In order to let 1800 frequency be the priority, set 1800 frequency cell to be high priority cell in which CBQ equals 0 and CBA equals 0 and Set 900 frequency cell to be low priority cell in which CBQ equals 1 and CBA equals 0.

900M cell：CBQ = 1，CBA = 0，C1=15900M cell：CBQ = 1，CBA = 0，C1=15

1800M cell：CBQ = 0，CBA = 0，C1=10

Cell selection after MS powered onCell selection after MS powered on

When PT doesn’t equal to 11111,

C2＝C1＋CRO－TO×H（PT－T）

When PT＝11111,

C2＝C1－CRO

In which：

Use PT/TO to reduce C2 value in fixed time so as to reduce

C2 Parameter

In which：

When x<0，H（x）＝0；

When x≥0，H（x）＝1

�CRO：cell reselect offset

�TO：temporary offset（temporary value of C2, In this period of time, C2

depends on PT. ）

�PT：penalty time

reselection of this cell.

Dual-band Network Mobile Standing Principle 1

� DCS1800 Network as priority

900M cell：C1=15，C2=5

Cell selection in idle Cell selection in idle Cell selection in idle Cell selection in idle modemodemodemode

� In idle state, MS sets calls and finishes it in GSM1800.

� After the call, MS resides in GSM1800.

1800M cell：C1=10，C2=20

Dual-band Network MS Standing Principle 2

� GSM900 network as priority

900M cell：C1=15，C2=21

Cell reselection in idle mode

� In idle state, MS sets calls and resides on GSM900.

� After the call, reselect to reside on GSM 900 network.

1800M cell：C1=10，C2=16

Handover

� Handover can be classified into the following:� Rescue handover:

� Interference handover

� Strength handover

� Quality handover

� TA handover� TA handover

� Fast fading handover

� Marginal handover� PBGT handover（Better Cell）

PBGT Handover

PBGT(n) = ( RXLEV_NCELL(n) －－－－ (RXLEV_DL+PWR_C_D))－－－－

(min(MS_TXPWR_MAX(n), P) －－－－ min(MS_TXPWR_MAX, P))

- MS_TXPWR_MAX：maximum allowable Tx power of MS in serving cells

� RXLEV_DL：DL level mean in this measurement report

� PWR_C_D：Difference between BTS max power and reported BTS power

� MS_TXPWR_MAX(n) ：MS max allowable Tx power in the adjacent

cell

� P：MS maximum power

� RXLEV_NCELL(n)：DL level mean of the adjacent cell

Traffic Handover

� Traffic Handover� Handover because of traffic. This happens when the serving cell is or on

the way to becoming congested while adjacent cell is relatively idle. MSC sends Handover Candidate Enquiry message to BSC and some MS are handed over from source cell to target cell.

� Candidate principle. BSC will select from specific cells the cell with worst quality to be handover candidate and apply handover from MSC. Guidelines are uplink and downlink reception quality, uplink and downlink reception level, and MS-BTS distance. Use weighting average Guidelines are uplink and downlink reception quality, uplink and downlink reception level, and MS-BTS distance. Use weighting average equation to get cell service quality.

� Handover target cell limitation. Candidate MS can’t be MS that its adjacent cell measurement report doesn’t include any cell in the list provided by MSC.

� Handover time limitation. The interval between last handover time of candidate MS and current time is smaller than minimum allowable handover time duration.This MS can’t be candidate in order to avoid frequent handover.

Priority Handover

� Priority Handover� Static priority� Dynamic priority

� Fast Fading Handover

When fast fading happens, and BSC catches that call signaling

strength value is lower than the threshold T for several times, BSC will

conduct fast fading handover and target cell is the cell in serving area.

Fast Fading Handover

Micro 1Micro 1Micro 1Micro 1

Micro 2Micro 2Micro 2Micro 2

AAAAAAAA1111

2222

3333 4444FastFastFastFast----moving MSmoving MSmoving MSmoving MS

RH TH=RH TH=RH TH=RH TH=----96 dBm96 dBm96 dBm96 dBm

RH N=4RH N=4RH N=4RH N=4

Set Micro2 to be Set Micro2 to be Set Micro2 to be Set Micro2 to be cell in serving cell in serving cell in serving cell in serving areaareaareaarea

Multi-band Indication

Multi －－－－bandReport

Indication

0 MS reports measurement result of 6 adjacent cells o f which signaling is strongest and NCC is known and allowab le, regardless of which band they belong to.

1 MS reports measurement result of one adjacent cell of all band (band which serving cell belongs to excludes) with strongest signaling in reported adjacent cell table. On remai ning area report adjacent cells of the band of serving cell. If ther e are still area left, adjacent cells of the band of serving cell. If ther e are still area left, report other adjacent cell regardless of the band.

2 MS reports measurement report of two adjacent cells of all band (band which serving cell belongs to excludes) with strongest signaling in reported adjacent cell table. On remai ning area report adjacent cells of the band of serving cell. If ther e are still area left, report other adjacent cell regardless of the band.

3 MS reports measurement report of three adjacent cel ls of all band (band which serving cell belongs to excludes) with strongest signaling in reported adjacent cell table. On remai ning area report adjacent cells of the band of serving cell. If ther e are still area left, report other adjacent cell regardless of the band.

Directed Retry

� Definition� In designation process, if serving cell has no

channel to allocate to, system will use directed retry function to allocate other channel of adjacent cells for MS.

� Function� Function� This is a special handover process which can

reduce call drop. � Type

� It’s categorized into intra-BSC directed retry and inter-BSC retry. The former needn’t MSC involvement while the later calls for MSC interaction.

Handover Algorithm

� Recommended Path Loss/TA algorithm� When path loss is greater than Lmax, or TA is greater

than TAmax, handover will be demonstrated from cell 2 to cell 1.

� When path loss is smaller than one threshold Lmin, and TA is smaller than TAmin, handover will be and TA is smaller than TAmin, handover will be demonstrated from cell 1 to cell 2 .

Cell 2

Cell 1

Lmax

Handover Algorithm

� Take handover model of path loss L for example:

Cell 2

Lmin

Cell 1

HandoverHandoverHandoverHandoveralgorithmalgorithmalgorithmalgorithm

Path lossPath lossPath lossPath loss C/I C/I C/I C/I algorithmalgorithmalgorithmalgorithm

Channel Allocation Algorithm

� Subcell channel request

Reaches cell handover threshold and MS Reaches cell handover threshold and MS Reaches cell handover threshold and MS Reaches cell handover threshold and MS supports subcell 2 dualsupports subcell 2 dualsupports subcell 2 dualsupports subcell 2 dual----bandbandbandbandHandover Handover Handover Handover

judgejudgejudgejudge

Target Target Target Target channel channel channel channel selectionselectionselectionselection

Subcell 2 channelSubcell 2 channelSubcell 2 channelSubcell 2 channelSubcell 1 channelSubcell 1 channelSubcell 1 channelSubcell 1 channel

satisfy unsatisfy

IntraIntraIntraIntra----cell cell cell cell handoverhandoverhandoverhandover

Path loss or C/IPath loss or C/IPath loss or C/IPath loss or C/I

UL & DL UL & DL UL & DL UL & DL interferenceinterferenceinterferenceinterference

If source cell is subcell 1, system will selectIf source cell is subcell 1, system will selectIf source cell is subcell 1, system will selectIf source cell is subcell 1, system will select

Subcell 2 channel only; If source cell is Subcell 2 channel only; If source cell is Subcell 2 channel only; If source cell is Subcell 2 channel only; If source cell is

subcell 2 , system will select subcell 1 subcell 2 , system will select subcell 1 subcell 2 , system will select subcell 1 subcell 2 , system will select subcell 1

channel only.channel only.channel only.channel only.

If source cell is subcell 1, system will select

Channel Allocation Algorithm

� Subcell channel request when conducting handover

InterInterInterInter----cell cell cell cell handover handover handover handover or directed or directed or directed or directed retryretryretryretry

Exterior Exterior Exterior Exterior handover in or handover in or handover in or handover in or exterior exterior exterior exterior directed retrydirected retrydirected retrydirected retry

System can only select subcell 1System can only select subcell 1System can only select subcell 1System can only select subcell 1

If source cell is subcell 1, system will select

Subcell 2 channel only; If source cell is

Subcell 2 , system will select subcell 1

channel only.

CoCoCoCo----locationlocationlocationlocation

NonNonNonNon----colocationcolocationcolocationcolocation

Dual-band Co-bcch Parameters

� SubcellUsed: cell use subcell or not � description： whether to use subcell or not� value： 0：not use 1：use� setting： 1

� FreqBand: band of subcell No.1� FreqBand: band of subcell No.1� description：band of subcell 1 is the frequency band

that subcell 1 is using

� value： 1 value connotaion

0 Basic GSM900 band P-GSM（（（（ARFCN = 1 ~ 124））））

1 Extended GSM900 band E-GSM（（（（ARFCN = 0 ~ 124，，，，975 ~ 1023））））

2 DCS1800 band DCS1800（（（（ARFCN = 512 ~ 885））））

3 Railway GSM900 band R-GSM（（（（ARFCN = 0 ~ 124，，，，955 ~ 1023））））

4 GSM1900 band GSM1900（（（（ARFCN = 512 ~ 810））））

7 GSM850 band（（（（ARFCN = 128~251））））

Dual-band Co-bcch Parameter� SubFreqBand: frequency band which subcell No.2

uses� description：frequency band which subcell No. 2 uses� value： see the above table� setting： 2

� HoControl: handover control� Description：In criteria, various kinds of handover triggering

conditions are described. What’s more, micro-cell’s introduction Description In criteria, various kinds of handover triggering conditions are described. What’s more, micro-cell’s introduction brings about various kinds of handover algorithm. It’s unnecessary sometimes to demonstrate other handover type besides handover based on reception strength and quality. HoControl defines handover type that must be realized in the cell.

� value： see the table� setting：1 LocatiLocatiLocatiLocati

ononononconnotationconnotationconnotationconnotation

bit18bit18bit18bit18 1111：：：：subcell handover are allowed due to path loss and TAsubcell handover are allowed due to path loss and TAsubcell handover are allowed due to path loss and TAsubcell handover are allowed due to path loss and TA0000：：：：subcell handover are not allowed due to path loss subcell handover are not allowed due to path loss subcell handover are not allowed due to path loss subcell handover are not allowed due to path loss and TAand TAand TAand TA

Dual-band Co-bcch Parameter

� PathLossMax : maximum value of path loss� description： maximum value of path loss and one of

subcell handover parameter.

� value： 0~150 dB� setting：126dB (by default)

� PathLossMin: minimum value of path loss � description： one of parameter of subcell handover

and the minimum value of path loss.

� value： 0~150 dB� setting：120(by default)

Dual-band Co-bcch Parameter

� SubCellTAMax: maximum value of TA� description： parameter of subcell handover and the

maximum value of TA. value： 0~63� setting： 1(by default)

� SubCellTAMin: minimum value of TA� description：parameter of subcell handover and the

minimum value of TA.

� value： 0~63� setting： 0(by default)

Form a pattern with GSM900 ensuring network coverage and DCS1800 absorbing the traffic left.Things shall be taken into account to ensure the two network will not be congested and there are no

� ObjectiveObjectiveObjectiveObjective

Traffic Control Strategy

congested and there are no unnecessary cell reselection and dual-band handover.

Cell reselection and handover are usually conducted within the frequency except when MS stays in blind spot or signaling strength of other frequency is much higher.

� PrinciplePrinciplePrinciplePrinciple

� Cell belongs to designated PLMN ？

Cell Selection

� Cell are not barred ？

� LAC of cell are not prohibited from roaming ？

� C1>0 ？

If the above are fulfilled, MS will stand on this cell.

In PHASE2+ criterion，cell priority parameter are added to BCCH broadcast message.

CBA CBQ Cell Select Priority Cell Reselect Priority

� CBQ（（（（Cell Bar Qualify ））））and CBA （（（（Cell Bar Access ））））

Cell Selection

0

1

0

1

0

0

1

1

Normal

Barred

Low

Low

Normal

Barred

Normal

Normal

Cell priority are defined based on setting of CBQ and CBA.

900M900M900M900M

1800M1800M1800M1800M

Cell Selection

PRI

C1

Make priority level GSM 1800 is higher than that of GSM 900, thus dual-band MS will first choose to be connected to

GSM1800 and then GSM 900.

Make priority level GSM 1800 is higher than that of GSM 900, thus dual-band MS will first choose to be connected to

GSM1800 and then GSM 900.

C1>0C1>0

1800M1800M1800M1800M

C1=10C1=10C1=10C1=10CBQ = 0CBQ = 0CBQ = 0CBQ = 0，，，，CBA = 0CBA = 0CBA = 0CBA = 0

C1=10C1=10C1=10C1=10

Cell Selection

900M900M900M900M

CBQ=1,CBA=0CBQ=1,CBA=0CBQ=1,CBA=0CBQ=1,CBA=0C1=15C1=15C1=15C1=15

� cell reselection setting principle

� CRO of 1800 cell is at least 10 dB greater than 900

� Increase weighting of GSM 1800 by adding CRO value, and value

Cell Reselection

added is up to loading condition of GSM 1800.

� Try to avoid detached island effect due to great CRO value.

Cell1Cell1Cell1Cell1

Cell 2Cell 2Cell 2Cell 2

Cell Reselection

Cell 1 can’t be accessed or fault occurs in cell 1?

Are there cell 2 that offer better services?

When conducting cell reselection, MS will sort and select adjacent cells based on their priority level and check whether the selected cell fulfills the standing condition. If conditions are met, MS will stand on this cell.


C1=5C1=5C1=5C1=5，，，，C2=15C2=15C2=15C2=15

Cell Reselection


Cell 2Cell 2Cell 2Cell 2C1=10C1=10C1=10C1=10，，，，C2=5C2=5C2=5C2=5

1800M cell1800M cell1800M cell1800M cell

rescue PBCG

Dual-band Handover

When GSM 900 and GSM 1800 share the same site, there will be lots of PBGT handover( handover due to better cell) in dual-band network coverage area. In the condition that both GSM900 and GSM 1800 have a favorable coverage, PBGT handover will occupy 80% of the total handover, as a result, this should be prohibited.


rescue handover

PBCG handover

�Rescue Handover


Dual-band Handover

When handover is to be conducted, cell fulfilling the requirement outside the band gives priority to fulfilling cell in the same band.


�PBGT handover


Dual-band Handover

When PBGT handover is conducted, MS can either be handed over to cell in the band or outside the band. But we suggest to make the condition of handover outside the band more rigorous. The degree of rigor is up to cell load.


Adjacent cell1Adjacent cell1Adjacent cell1Adjacent cell1（（（（7777））））

Serving cellServing cellServing cellServing cell

Adjacent cell 1111（（（（4444））））

Dual-band Handover

� dynamic optimization handover algorithm

Serving cellServing cellServing cellServing cellAdjacent cell2

（（（（5555））））

Serving cellServing cellServing cellServing cell

Adjacent cell 2222（（（（5555））））

When there are no traffic ,adjacentcell 2 gives priority to adjacent cell 1.

With the change of traffic, priority level of adjacent cell2 may be lower than adjacent cell 1.

� In network running, percentage of channel occupied will be

estimated. When the threshold is reached, handover will be

conducted so that MS near the cell margin will be handed over to

� Traffic handover algorithm

Dual-band Handover

conducted so that MS near the cell margin will be handed over to

an adjacent cell.

� Advantage of ZTE handover algorithm� Handover due to traffic volume is provided, thus congestion of GSM

1800 is avoided.

� Directed retry between the two band. For example, when GSM

1800 is congested, call will be handed over to BSC or MSC to

which GSM 900 belongs to and enhance call through rate of

Dual-band Handover

which GSM 900 belongs to and enhance call through rate of

GSM 1800. Fast fading handover algorithm targets fast fading and

helps to avoid call drop caused by bad quality of the serving cell.

� Interval protection. Limit the handover times between dual-band cells

in order to reduce signaling flow in BSC, and finally to guarantee the

favorable call quality.

To control cell selection: C1，CBA，CBQTo control cell selection: C1，CBA，CBQ

To control cell reselection：C2To control cell reselection：C2

Traffic Control Means

To control cell reselection：C2To control cell reselection：C2

To control dual-band handover

：PBGT，priority

To control dual-band handover

：PBGT，priority

Traffic Balance—method 1

� In MS idle mode, select DCS1800 to stay and start calls.� Make DCS1800 set the priority by setting CBA and

CBQ.� Use C2 as criterion for reselection

900M cell：C1=15，C2=5

1800M cell：C1=10，C2=20


� When MS is in call state, it’s better to stand on the band where call is initiated so as to avoid unnecessary handover. � PBGT handover between different band is prohibited.� multi-band report setting� Only rescue handover is allowed for foreign � Only rescue handover is allowed for foreign

frequency.


� When MS is in idle mode, it will select best

network.

� Priority level of GSM 1800 and GSM 900 is the same

� Use C2 as reselection criterion� Use C2 as reselection criterion

� Difference of C2 of the two band is less than 6dB；

900M：C1=18，C2=20

1800M：C1=10，C2=16

Traffic Balance—Method 2

� When MS is in call state, make DCS 1800 a priority and

keep traffic balanced through handover

� PBGT handover between different band is allowed

� Multi-band indicator settingMulti-band indicator setting

� Flexible control of rescue handover

Traffic Balance-Other method

� Other method to control traffic� Traffic handover

�Band control� threshold

� directed retrydirected retry�duration

� priority handover�Static priority�Dynamic priority

Catalog

� Dual-band Network Overview� Dual-band Network Planning Strategy� Dual-band Network Optimization Parameter

Adjustment� Dual-band Network Optimization Cases

� Network Construction� Ever since ZTE dual-band network is adopted by Xi’an

Telecom in December of 2002, DCS1800 network running by Xi’an Telecom exceeds 100 with Trxs over 2000.

� There are two Topomap existing in current network:

Xi’an Dual-band Network

� ZTE GSM900，ZTE DCS1800；A serial� Siemens GSM900, ZTE DCS1800；B serial

� Co-location and co-site

Dense urban Suburb

900M


1800M

continuous coverage hotspot coverage


� Traffic Balance- Network A� In idle mode, give GSM 1800 priority and start calls on

GSM 1800.� Try to stand on GSM 1800� PBGT handover of foreign fequency is prohibited


� Traffic Balance-Network B

� In idle mode, give GSM 900 priority

� In call mode, select GSM 1800 to share the traffic

� Open PBGT；� Open PBGT；

� Traffic handover

ERL

600

800

1000

1200

ZTE_DCS


0

200

400

600

ZTE_

DCS

SIEM

ENS

ZTE_

DCS

SIEM

ENS

ZTE_

DCS

SIEM

ENS

ZTE_

DCS

SIEM

ENS

ZTE_

DCS

SIEM

ENS

ZTE_DCSSIEMENSZTE_DCS


SDCCH block rate

Busy-hour voice channel occupancy times (including handover)

Busy-hour voice channel overflow times (including handover)

TCH block rate

Radio access success rate

Traffic(Erl)

Handover success rate(%)

Call drop times

Voice channel call drop rate

Call drop ratio

0.26% 213201.00 587.00 0.28% 99.47% 1572.73 91.85% 1012.00 0.47% 93.24

0.29% 222599.00 624.00 0.28% 99.43% 1631.92 91.68% 1014.00 0.46% 96.56

0.22% 223967.00 597.00 0.27% 99.51% 1652.17 91.92% 1048.00 0.47% 94.59 0.22% 223967.00 597.00 0.27% 99.51% 1652.17 91.92% 1048.00 0.47% 94.59

0.12% 243280.00 1013.00 0.42% 99.47% 1818.79 91.41% 1119.00 0.46% 97.52

0.28% 221836.00 562.00 0.25% 99.47% 1632.34 91.59% 1005.00 0.45% 97.45

0.06% 139721.00 266.00 0.19% 99.75% 978.16 91.72% 641.00 0.46% 91.56

0.23% 199751.00 530.00 0.27% 99.50% 1755.10 91.79% 892.00 0.45% 118.06

GO_NA10_E1_1 GSM Dual-Band Network Planning & Optimization

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