opt presentation 2

CDMA RF Optimization Introduction

CDMA CORE ENGINEERING 2001

Agenda

• Dec.5th Morning: 9:00~10:30 Optimization presentation.

10:30~10:45 Break

10:45~12:00 Optimization presentatio• Dec.5th Aferrnoon: 1:00~2:30 Agilant 7435, OPAS 32

introduction.

2:30~2:45 Break

2:45~5:00 Agilant 7435, OPAS 32

Practice. Q&A• Dec.6th Morining: Introduction of Call processing. Q&A.• Dec.6th Afternoon: Drive test equipment,post software

practice.

1. Optimization goals.

2. What need to be optimized in CDMA network?

3. What are needed for optimization?

4. Procedure for optimization?

5. Case study.

6. Parameter tuning optional.

7. Call processing,

8. PMSUM and CDL.

Content

1. General goal: To improve the performance of the CDMA RF

network.

2. Specific goals:

a. Drop call rate: should be less than 3%

b. Access failure: should be less than 5%

c. Coverage:

Unicom requirement:

Optimization goals (1)

室内室外室内室外室内室外特大城市覆盖率 98% 85% 98% 88% 99% 92%一般城市覆盖率 95% 82% 97% 85% 98% 87%市郊覆盖率 85% 70% 90% 75% 95% 80%郊县覆盖率 65% 50% 70% 57% 75% 65%

1300万 3000万 5000万


• Three parameters can be used for coverage evaluation.

　 Ec/Io, RSSI, TX(mobile)

• Ec/Io: Ec/Io is the measurement of usable energy each chip as compare to the total noise at a particular location.

Normally Ec/Io should greater than –12dB

• RSSI: Received Signal Strength Indicator.

Acceptable value range –40~-90 dBm

• Tx Power: Mobile transmitted power.

Acceptable value should less than +17dBm


• Voice Quality:

FER: The percentage of frames discarded due to too much errors.

The average FER on both forward and backward should be less than

3%.

Five key elements in RF optimization:

• PN.

• Neighbor

• Handoff Parameter.

• BTS TX Power.

• Antenna

• Cell radius

What need to be optimized

1. Two potential issue for PN:

A. Co-offset interference

B. Adjacent offset interference.

2. Two ways to find the problem:

A. By carefully study the PN planning.

B. Investigate drivetest data, to find if there are drop calls caused by

PN issue.

PN

• Define neighbors which can be available for handoff candidates

• Max 20 neighbors can be added to neighbor list, but not necessary.

• Neighbor list should include all sectors that handoff may happened.

• Neighbor has priority, which means from 1 to 20, the smaller the number, the higher possibility of handoff.

Neighbor list

1. Four type of hand off parameter:

Tadd, Tdrop, Ttdrop, Tcomp.

2. Parameter impacts:

Too Low Too High

Taddhigh rate of PSMM, increaseunneccssary handoffs,require

poor FER,may cause handoffdelay, high MS Tx power at

Tdropincrease cell size, use up moretraffic channels

reduce size of handoff zone,increase ping-pong handoff

Tdrop-Tadd increase in messaging increase use of Tch resources

TTDrop increase ping-pong handoff more three-way handoff

Tcomphigh rate of PSMM,require moretraffic channel May cuse delay handoff poor FER

Hand off Parameter

1. Why need optimize BTS pilot power.

a. to expand coverage.

b. to minimize active Pilot in multi-Pilot area

2. How to adjust BTS pilot power:

a. if you need to expand coverage, Tx Power should be higher.

set higher value to parameter: SifPilotpwr

b. if you need minimize active Pilot , Tx Power of useless pilot

should be lower

set higher value to parameter: SifPilotpwr

BTS Pilot Power Optimization

• Antenna is the most important parts of RF network

• Adjust antenna is one of the most effective way for optimization.

• Antenna adjustment include:

• bearing

• downtilt

• height

• Negative effects should be considered which include:

• distortion of antenna pattern when downtilt is too big.

• too big downtilt may lead to increasement of soft and softer

handoff.

Antenna

What are needed for optimization

1. Tools needed: drive test software– Agilent 7435

post processing software– opas32 or CI

CDMA mobile phone, 8K EVRC

needed.

Scanner (optional) ,Car: Power needed

2. Person needed: Team leader, RF engineer.

CBSC engineer, driver

3. Information needed: Simulation results, PN planning

Neighbor planning, system configuration info,map with site

Location.

Agilent 7435

ScannerComputer

MobileGPS

Equipment installatin and statusverification

Spectrum clearing

Tools setup

Optimization preparation

RF parameter databaseverification

Go to next page

System info collectionSite location, system

Design para,etc

Network Design Verification

Location, PN, Neighbor


Single cell functional test

Optimization

General procedure for Optimization (1)

General procedure for optimization(2)

Commercial service

Cluster test

Network test and detail Problem resolution

Indoor test

Full coverage survey And warranty Testing

From previous page

optimization

Optimization Step

• The complicated optimization procedure can simplified into five steps:

– Network design verification

– Preparation for RF optimization

– Single cell functional test

– Cluster test

– Optimization for the whole network

• Purpose: to make sure the system is properly designed.

• Following information need to be collected and verified:

• PN planning.

• Neighbor

• site location.

• simulation result

• antenna setting in simulation

• system performance prediction


• To make sure equipment, especially BTS is properly installed according to system design

• To make sure parameter is set to the right value in database.

• key parameter: PN, Neighbor, Sifpilotpower, Tadd, Tcomp, Tdrop, TTDrop.

• To make sure all the equipment in service.

• For interference, spectrum clearing should be performed when

needed

• Get enough information for Optimization, include:

• map, site location, etc.

Preparation for RF optimization

• Purpose of Single cell functional test is to ensure:

• The cell site hardware is functional

• The ability to place L-M calls and M-L calls on each sector

• Antenna are pointing correct direction and PN is correct

• Mobile receive power and Ec/Io are normal

• Softer&soft handoffs occur.

• Redundancy function

Single cell functional test (1)

Single cell functional test (2)

• Route criteria:

•Followings should be tested and recorded:

• At test point: relative position to site, Ec/Io, PN, call records,

RSSI, FER.

• Make sure HO successfully for all sector on both direction.

• Test Redundancy Function of BBX, GLI, CSM.

Test point

Test point

Test point

HO test

HO test

HO test

Cluster Test (1)

• Purpose: to characterize the coverage and performance of a group (cluster) of cell that provide contiguous coverage. Problems will be record in cluster test.

•Sample route

EndCluster Metric

StartDesired coverage area

Missing Site

Pathloss

Interference

No coverage desired

Drive　routes　within　boundary　of　the　desired　coverage　area

Cluster Test (2)

• Followings should be tested and recorded in cluster test:

• If neighbors is correctly added in system.

• Srchwin_A, Srchwin_N, Srchwin_R, set properly.

• Any coverage holes exist.

• Any multi-pilot or no dominant pilot area exist.

• Call drop rate and Access failure rate.

• Voice quality

Optimization for the whole network(1)

• Purpose: Ensure each cluster is integrated into the overall network and prepare the CDMA system for commercial service.

• More detail test and analysis than cluster test will be performed

• Route:

• Inter-cbsc,inter-MSC

HO test included

•.

Optimization

Optimization for the whole network(2)

• Analysis include:

• neighbor list optimization.

• cell radius checks.

• RF coverage assessment

• elimination of pilot pollution,

• correction of database and equipment stability problems.

• interference

Case Study

• Drop call

• Multi pilot

• Coverage hole

• Access failure

• Neighbor missing

Case Study 1: drop call (1)

• Four reasons may lead to drop call:

Interference, poor coverage, pilot pollution, miss neighbor.

• Two type of interference:

• interference outside CDMA system:

• interference inside CDMA system: PN re-used.

• Poor coverage: have low RSSI, and high mobile TX power.

• Pilot pollution: more than three pilots have EcIo above Tadd

• Missing neighbor:

Case Study 1: drop call (2)

• General procedure of drop call trouble shooting

Good EcIo

Repeatable call drop

InterferenceCheck

Interference

ImproveBest server

done

Off Possible Interfering

cell

Up best server

Start adjust SifPilotPwrIn surrounding cells

New cell need

In3-way

DecreaseTTdrop

Smallest cell

Change SifpilotpwrDominant

Raise TDrop

Slow/Noadd

Check ReverseRSSI,equipment

RightneighborGood TX

Coveragelimit

Add neighborChange order

Window

Decode PSMM

Increasewindow

YY

Y NY

Y

N

Y

Y

Fix

N

N

N

N

1

2

N

N

N

N

3

Y

Case Study 2: multi pilot

• Two situations of multi pilot: pilot pollution, lack of dominance,

• Pilot pollution can be defined as the existence of four or more pilots with Ec/Io values greater than Tadd.

• Lack of dominance can defined as low Ec/Io levels, numerous pilot with similar Ec/Io.

• Impact of pilot pollution:

• Bad FER

• Drop calls

• Waste of network resources

Case Study 2: multi pilot (2)

• real case: pilot pullution


• real case 1: no dominant pilot


• Method to correct the problems:

• pilot pollution: decrease the amount of energy to the problem

area,increase the best server power.

• lack of dominance:

• step 1: find at most three sectors which most suitable to

serve the area.

• step2: increase the power of the sectors wished to be dominant

• step3: decrease the power of sectors which interference.

Case Study 3: coverage hole (1)

• How to find a coverage hole:– By DM data, and mobile test

Investigate Tx Power, RSSI, Ec/Io by OPAS

– By SMAP data

RX level low in PMRM, no candidate Sector

– By CDL

Both active and candidates have low Ec/Io.


• Sample data:– Low RSSI– High mobile Tx Power– Low Ec/Io

CDMA TIME Rx dBm Tx Pow dBm Ec/Io dB

14:51:16 -102.33 17.79 -14.6114:51:17 -100.38 16.32 -14.914:51:18 -95.71 15.24 -14.8614:51:19 -101.74 14.2 -15.0214:51:20 -106.07 16.24 -14.5414:51:21 -105.49 15.76 -15.1914:51:22 -105.66 17.2 -15.1714:51:23 -105.1 19.68 -15.3314:51:24 -102.76 19.78 -15.1914:51:25 -104.18 19.27 -14.8614:51:26 -104.06 20.07 -14.6


• SMAP Sample data:

Time Message Type ACK SEQs Contents__15:26:25.365 ----> MS: PMRM AckSeq=7 MsgSeq=3 AckReq=0 Erased = 3 Total = 108 NumPilots = 1 -13__15:26:27.855 ----> MS: PMRM AckSeq=7 MsgSeq=4 AckReq=0 Erased = 3 Total = 111 NumPilots = 1 -14__15:26:28.650 ----> MS: PMRM AckSeq=7 MsgSeq=5 AckReq=0 Erased = 3 Total = 25 NumPilots = 1 -14__15:26:29.530 ----> MS: PMRM AckSeq=7 MsgSeq=6 AckReq=0 Erased = 3 Total = 15 NumPilots = 1 -16__15:26:29.840 ----> MS: PSMM AckSeq=7 MsgSeq=2 AckReq=1 Pilot Strengths (pn,str,active) (24, -17.00, keep=0)__15:26:29.840 <---- BS: ACK Order Msg AckSeq=2 MsgSeq=7 AckReq=0__15:26:36.330 DMTA ESN = 9f030952 cell=17 cic=6967(0x1b37) call id = 7256(0x1c58)

17 Call Release Start,Ahhhh!! RF Loss;


• Sometimes coverage hole may caused by interference.

• Judgment:

– Drop calls

– High FER

– Low Ec/Io

– High RSSI

– Low Tx Power

Case Study4: Access Failure

• Access Failure: defined as call attempts that failed to reach a TCH due to reasons other than normal termination.

• Possible reason:

– Blocked call

– Device not functioned

– PN Interference

– Interference during call set up

– Database error

– Multi pilot pollution

– Access Parameter wrong

Case Study 5: Neighbor missing

• High FER and drop call may be caused by strong pilot that not scanned or add to active.

• Several ways to find missing neighbor:

– Use drop call:

After drop call, check the PN mobile to sync. If the PN is not in Neighbor list, it should be added to neighbor list.

– By scanner:

Scanner search all PN offset. So compare the PN Ec/Io in scanner

and neighbor list set in database, missing neighbor can be found.

RF parameter tuning optional

• Forward power control parameters

• HO parameters

• Reverse link power control

• Access channel power control

• Sifpilot power

• Cell radius parameters


• Forward Power Control Parameters:– FER Target:

– FER Target can be change to get more capacity while trading off FER


• HO parameters:

Tadd, Tdrop, TTdrop,Tcomp

• Access channel power control:

NomPwr, NumStep

• Tch power control:

RPCEbNoMax, RPCThrsMax.

• SifPilotPower

• Cell radius:

SrchWin A, SrchWin N, SrchWin R.

RF parameter tuning optional- HO

• T_ADD: When Ec/Io>TADD, MS send PSMM

Transfer Pilot from neighbor to candidate set.

Range: -31.5~0

Step:0.5

Recommend:-12~-14

Database value:2 x actual EcIo


• T_drop: When EcIo<T_drop

MS start HO drop timer.

Range:-31.5~0dB

Step: 0.5

Recommend: -13~-16

Database value:2 x actual EcIo


• TTdrop:When active or candidate drop timer>Ttdrop

Remove active or candidate to neighbor

Range: 0.1~319 sec

Recommend: 4~6 sec

Database value: by table


• Tcomp:

when EcIo> Tadd transfer pilot from neighbor set to candidate set&

send a PSMM.

If EcIo> Active EcIo+Tcomp

MS send another PSMM.

Range: 0~7.5

Step:0.5

recommend:7.5

Database value: 2 x actual EcIo

RF parameter tuning optional-Reverse link Power Control

• MS transmit first probe power at mean out power of

MeanTx= -MeanRX-73+NomPwr(dBm)+InitPwr(dBm)

• each access probe sequence contains of up to 1+Numstep

• Subsequence probes increase power

by PwrStep until obtain a response

• If necessary another sequence will be

transmitted after Bkoff delay.

RF parameter tuning optional-Reverse link Power Control

• NomPwr: Access channel nominal power offset

Range: -8~7

Recommend: 3

• InitPwr: Init Power For Access

Range: -16~15

Recommend: -3

• High power provide high probability the BTS detect probe, but also

provide high interference on reverse link.

RF parameter tuning optional-Reverse Power Link Control

• RPCMaxEbNo: Max EbNo in reverse traffic channel.

• Max threshold restrict any MS from requiring too much Eb/No

• Include input for both main and diversity branches.

Range: 2~14.9dB

Step: 0.1

Recommend: 11dB

• Higher RPCMax yeild better FER at the cost of higher interference.

RF parameter tuning optional-SifPilotPower

• The expected power of each pilot channel at the top of Sif frame.

Range: -127~127dBm

Step: 0.1

Recommend: 33dBm

Database value:10 x actual value.

RF parameter tuning optional-Cell size:PamSz

• CellRadius:define the radius of the cell. PamSz is auto-set by it.

• PamSz: access channel preamble size.

• The access channel preamble:

– MS transmit frame of 96 zero at 9600

– Assists base station in requiring subscribes

– Reduce cell size may low PamSz.

• PamSz: number of access preamble channel frames

Range:1~16

RF parameter tuning optional-Cell size: SrchWin A

• MS search window size for pilot of active and candidate sets due to multipath delay.

• The size should be enough to coverage 95% of the expect multipath from the serving cells.

• Too small window size may lead to not detecting useful multipath energy.

• Range: 4~452 chips

• Recommend start: 28 chips

RF parameter tuning optional-Cell size: SrchWin N,SrchWin R

• SrchWin N: MS search window size for pilot of neighbor set

• SrchWin R: MS search window size for pilot of remaining set

• The size should be large enough to cover different time delay between MS and potential cells.

• Too small: increase chance to miss pilot.

• Too big: handoff delay may cause by long search time.

• Recommend:

– SrchWin N: 60 chips

– SrchWin R: 80 chips

RF parameter tuning optional-Cell size: Srch Window vs Distance Delay

Srch Win 0 1 2 3 4 5 6 7Window Size(chips) 4 6 8 10 14 20 28 40Delay(us) 1. 6 3. 3 4. 9 6. 5 9. 8 14. 6 21. 2 30. 9Distance(kilo) 0. 4 0. 8 1. 2 1. 6 2. 4 3. 6 5. 2 7. 5Srch Win 8 9 10 11 12 13 14 15Window Size(chips) 60 80 100 130 160 226 320 452Delay(us) 47. 2 63. 5 79. 8 104. 2 128. 6 182. 3 258. 8 366. 2Distance(kilo) 11. 5 15. 5 19. 5 25. 4 31. 4 44. 5 63. 1 89. 4

Callprocessing Introduction

• Two Sample:– Mobile to land Origination Callprocessing

– Land to Mobile Terminated Callprocessing

Callprocessing- Mobile origination

MS CBSC MSC

Origination Message

Base Station Ack Order

Complete L3 Info: CM Service Request

Mobile Information Directive

Setup

Call Proceeding

Assignment Request

Channel Assignment Message

Tch Preamble

BS Ack Order

MS Ack Order

a

c

b

d

f

e

g

h

i

j

aa

k

Callprocesing- Mobile Oringination Call

MS CBSC MSC

Origination Continuation Message

CM Service Request Continuation

Service Connection Message

Service Connect Complete

Assignment Complete

Alerting

Ringback Tone

Connect

Connect Ack

l

m

n

o

q

p

s

r

t

Callprocesing- Mobile Oringination Call

a- MS oringination messageb- BS acknowledges messsagec- BS CM service request messaged- MSC MID messagee- BS setup message(optional)f- MSC Call Proceeding message(optional)g- MSC Assignment Request messageh- BS Channel Assignment messagei- MS TCH Preamblek- Mobile station acknowledge orderl- Origination continue message continue to next page

Callprocessing-Mobile Origination Call

m-CM service request continue message.

n-Service Connect Message/Service Option Response Order

o-Service Connection Completion Message

p- Assignment Complete Message

q- Alerting Message (Optional)

r- Ring Back

s- Connect Message (Optional)

t- Connect Acknowledge Message (Optional)

Callprocessing- Mobile Terminated Call

MS CBSC MSC

Paging Request

Paging Message

Paging Response

Complet L3 Info: Paging Response

Base Station ACK Order

Mobile Information Directive

Setup

Call Confirmed

Assignment Request

Channel Assignment Message

TCH Preamble

BS Ach Order

a

b

c

d

e

h

f

g

i

j

l

k

Callprocessing-Mobile Terminated Call

MS CBSC MSC

Assignment Complet

MS ACK Order

Service Connect Message

Service Connect Complete

Alert with info

MS Ack Order

Alerting

BS Ack OrderConnect

Connect Ack

Connect Order

o

n

p

q

r

s

v

t

u

m

w

Callprocessing- Mobile Terminated Call

a- Paging Request Message,MSC->BS

b- Paging Request Message,BS->MS

c- Page acknowledge message over access channel

d- Paging response

e- BS setup message(optional)

f- MSC Call Proceeding message(optional)

g- MSC Assignment Request message

h- BS Channel Assignment message

i- MS TCH Preamble

k- Mobile station acknowledge order

l- Origination continue message

PMSUM Introduction

• What is PMSUM?

– Performance Management Report

– It is network performance statistics that are displayed from the CBSC.

– It is collected by OMC and store in UNO.

– It may be available on the intranet. For china unicom CDMA systems, PMSUM is available on following website:

http://cdmacore.cig.mcel.mot.com/performance/btg/btg.html










PMSUM Introduction

• What information is provided by PMSUM(1):

– Eight main parts of the PMSU(1):

• PMMCC System Performance: contain information on channel usage, OOS time, originations, terminations,access failures, Rfloss and channel usage time per attempt.

• CEM report: information on unplanned BTS availability,total BTS availability, alarms.

• PMSUM report: Cell RF loss, access report, HO report, MM summary, carrier summary, worst 15 cells failing above 1%

• PMTRAF report: Information on traffic data.

PMSUM Introduction

• What information is provided by PMSUM(2):

– Eight main part of the PMSUM(2):

• CDL CFC Analysis: Call summary statistics,CFC summary based on CDL information.

• Inter-CBSC soft handoff report:

• CPU Utilization graphs

• System Performance Graphs:

include: RF loss, Access Failure, Handoff Failure, Traffic hours, BTS availability, CFC percent, Call attempt by hours,walsh code usage by hours.

PMSUM Introduction – Entering page

PMSUM Introduction – PMSUM

PMSUM Introduction - CEM

PMSUM Introduction - PMTRAF

PMSUM Introduction – CDL CFC

PMSUM Introduction

Graphic Example:

PMSUM Introduction

• What can PMSUM be used for:

– An overview of system performance.

– Detail performance on device stability.

– Valuable information on system character.

– Helpful information for optimization plan.

– Can be a measurement of optimization job.

– Used for system expansion plan.

CDL Introduction

• CDL: Call detail log, detail information of calls processing logs stored in OMC.

• How to get CDL:– By “browse” command under CLI: Command format: > Browse cdllog [startdate] [enddate] [starttime]

[endtime] [parameters] parameters include: call setup parameters, hard handoff parameters, soft handoff count parameters, inter CBSC information, last three

RF connection parameters, first mobile assisted handoff parameters, last mobile assisted handoff parameters, last softer handoff parameters,call setup event, call quality parameters, vocode bypass parameters, packet data parameters, directory paremeters.

Detail information is in: System Command Reference Manual

CDL Introduction

• Key CDL parameter for optimization:– Startdate,Enddate,Starttime,Endtime: browse CDL within specified time interval.– Mid, ESN: browse CDL related to specified MS– Acc_PN_offset,Acc_BTS,Acc_Sector browse CDL related to specified BTS– CIC_span, CIC_Slot,XCDR browse CDL related to specified CBSC device.– CFC Call final class. Identify the final disposition of the call

CDL Introduction

– Key value of CFC:

CFC1:Normal Network Initiated Call Termination

CFC4:RF Loss

CFC26:Call Control

CFC31:Normal Mobile Initiated Release Call Termination

CFC60:Protocol Error between BSC and MSC

– LMM_Setup_event:

last call setup event received at MM.

opt presentation 2

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