cdma drive test and optimization.docx

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CDMA Drive Test and Optimization

CDMA Optimization Subjects Course objectives:

· To master air interface protocols and signal procedure· To master DT test data analysis

· To master “Monolog, access failure, call drop, handoff failure, FER” analysis and solutions

Contents

1. DT Introduction ,Analyzing Method Features ,Test Introduction ,Test Equipment and Test Classifica

2. DT Test Analyzing Procedures, Flow chart, Flow Note

3.

DT Test Analyzing Application in Optimization,coverage analyzing and How to evaluate network

coverage performance

4 Popular optimization methods to improve coverage and Analyzing Application in Call Failure

5.

CDMA Call failure reasons analyzing

6.

CDMA Call failure caused by wireless link fading and Call failure caused by forward and reverse

imbalance

7 .CDMA Call failure caused by access and handoff collision and Call failure caused by resource limit

8.

CDMA Call failure caused by too narrow MS search window and Call failure caused by low paging

channel gain

9. CDMA Call failure caused by unsuitable access parameters

10. Some analyzing when MS termination call is not successful

11. Drive Test Application in Call Drop Analyzing

12 Call Drop reason analyzing and Call drop Caused by Access and Handoff Collision

13 Call drop caused by Forward and Reverse Imbalance and Call drop caused by Forward Interference

14 Call drop caused by Reverse Interference and Call drop caused by F-TCH Power Limitation

DT Introduction ,Analyzing Method Features

,Test Introduction ,Test Equipment and Test

Classification

DT Introduction DT test is the main method in CDMA network optimization.

DT (drive test) is the method that MS moves on specific route of the coverage area and records

the performance data and positionDT analyzing is using the related software to give analyzing for DT data and give the judgment

for network quality in coverage, also gives solution or other scheme to improve.

DT Analyzing Method Features

1. Advantage

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http://www.sinauonline.50webs.com/cdmaoptim/dtflowchart.html



http://www.sinauonline.50webs.com/cdmaoptim/dtapplication.html





http://www.sinauonline.50webs.com/cdmaoptim/optimimprove.html




http://www.sinauonline.50webs.com/cdmaoptim/callfailure.html




http://www.sinauonline.50webs.com/cdmaoptim/fadingfailure.html





http://www.sinauonline.50webs.com/cdmaoptim/handofffailure.html



http://www.sinauonline.50webs.com/cdmaoptim/windowfailure.html





http://www.sinauonline.50webs.com/cdmaoptim/accessfailure.html




http://www.sinauonline.50webs.com/cdmaoptim/mscall.html




http://www.sinauonline.50webs.com/cdmaoptim/calldrop.html


http://www.sinauonline.50webs.com/cdmaoptim/calldropreason.html


http://www.sinauonline.50webs.com/cdmaoptim/callimbalance.html


http://www.sinauonline.50webs.com/cdmaoptim/callint.html































· According to DT the whole area signal coverage quality can be known. According to DT

analyzing software, the coverage quality can be given a statistics result and this can be used to

judge if the real coverage reach to the designing requirement;· According to DT software processing, where the coverage quality is good and where the

coverage quality is bad, it is very clear. This can help engineer to adjust working scheme for the

entire network;· DT test can record the real signal state and geography information for all the events(origination, handoff, drop calls). This will be very helpful to the event problem analyzing;

· In DT test, the geography features and real transmission environment can be observed; this is

very helpful to give judgment for problem;· According to DT test, optimization engineer can experience the subscriber feeling and can get

the directed information to locate the problem;

2. Disadvantage · Be absent of OMC traffic statistics data;· Be limited in wireless side to analyze;

DT Test Equipment For voice and data DT test, the necessary equipments are shown as Table

Note: · DT test software is TEMS, NEMO, ZXPOS CNT1, analyzing software is ACTIX,NEMO

ANALYZER ZXPOS CNA1;

· In data DT, test mobile and data card should be selected only one, and also confirm it can get tothe suitable data speed. Usually prefer to select data card.

· In data DT according to operator’s requirement, FTP downloading and uploading, or iperf

software are all suitable. Attention to select suitable FTP server in FTP downloading test.

DT Test Classification 1. Voice DT test: It includes coverage quality; origination quality; drop call; call quality andhandoff.



2. Data DT test: It includes average data transmission speed; forward and reverse average data

transmission speed.

DT Test Method Classification 1. According to loading information, it can be divided to “test with load” and “test without load”.

2. According to call holding time, it can be divided to “long call test” and “sequence call test”.

Test with load and test without load The evaluation test can be implemented in one of the three loading method: busy hour, unloaded(light load) hour or loaded hour.

Busy hour test means the test implemented when the current network traffic is busiest. This test

is suitable for the network that has already been operating for a period and can facilitate findingout existing problems in the network.

Unloaded (light load) test is implemented when there is no user or a small number of users. For

a network that has not undergone large scale of number allocation, the test can be implementedin the normal period. But for a network that has already undergone large scale number allocation,

the test can only be conducted at midnight when the traffic is small.

Loaded test check the network performance by simulating fixed loading condition throughadding loads in forward and reverse links. In the forward link, simulate traffic load by utilizingthe orthogonal channel noise simulator (OCNS); in the reverse link, apply the signal attenuator to

simulate the load. For a network which has not undergone large scale number allocation, the

loaded test can be implemented in normal traffic period.

While for a network with large scale number allocation undergone, the test can only be done at

midnight when the traffic is small, which can accurately simulate the load and on the other handcan reduce the influence the test brings on the subscribers.

The forward OCNS loading can only reflect the network performance at the wireless side, while

it can not reflect the processing capability of the system. The best reverse loading method is to

use a noise simulator to add noise at the receiving end of the base station. However, as it isdifficult to add a noise simulator to each base station, add reverse load through reverse load

simulator. For a network that has been operating for a period, generally busy hour test is adopted.

Long call test and sequence call test 1. Voice data test In the continuous long- time calling test, the call holding time is set to be the maximum value

and automatic recall will originate when a call drop occurs. This kind of calling features a small

number of calling times, and can better reflect the system handoff performance. It can be used toin the tests for some parameters such as coverage ratio, call drop rate, handoff success rate and

handoff zone rate, etc.

In a sequence calling test, the call setting-up time, call holding time and call interval are set



respectively to fixed values, and calls are originated periodically to test the network

performance. The periodical test can better reflect the system processing capability and the test

result is closer to the actual user situation. It can be used to test parameters such as callcompletion rate, paging response rate and call drop rate, etc.

2. Data DT test

According to the type of service, it can set with periodical call or continuouslong-time call. Generally, the former is used in testing the call completion rate of data service;while the latter is to test the items such as data throughput of single subscriber and signal sector,

data service handoff, etc. and the specific call duration can vary with the tested item.

DT test route selection According to test area, DT test can be divided to urban DT test and main roads DT test.

· Urban DT test is used to get the network performance in urban area;· Main roads DT test is used to get the network performance in the main roads, railway, and

waterway

According to test range, DT test can be divided to the entire area DT test and part area DT test.

· The entire area DT test is used to get to know the whole network performance;· The part area DT test is used in specific area for one problem.

DT test route designing principle: · Test path should be within the coverage range and avoid to repeating the same stretch;· For the BTE whose coverage is connected to repeater, test route should cross their related

coverage area to check the handoff performance;

· For BSC overlap area, test route should cross two BSC to check the handoff between two BSC;· For sing carrier and multiple carriers combined network, the test route for carrier handoff

should move to single carrier area from multiple carrier area and MS should use non-

fundamental carrier; Each single carrier coverage test route is same as before; According to

designing, the test route can be drawn or printed in map. The DT engineer and driver should befamiliar to the route and the driving speed is better in even speed (30~50km/h).

DT Test Analyzing Procedures



1. Requirement analyzing 1) Network coverage requirement information;

2) The current network cell site information;

3) System parameters configuration;4) The existing problem in current network;

5) Confirm the acceptance standard of the project;6) Confirm the interface with the customer;

2. Decide DT test plan DT test plan needs negotiation with customer. Commonly the following items need confirming;

1) Confirm test date;



2) Confirm test parameters: Calling mode is long call test or sequence call test; bury hour test,

without load test or with load test?

3) Confirm test route:

3. Preparation for DT test 1) Confirm vehicle is available and smoke lighter is OK;

2) Check all the equipments for DT test and prepare the cell site information table for software;

3) Some other accessories (like backup battery for handset);

4. DT test According to the designing test route, start test. Attention the following points in

test: 1) DT test engineer should cooperate with driver well in test, and help driver to be clear about

the route;

2) Save the test data correctly and the save file is better to use “ xxxxx year xx month xx day xx

place xx objective” format. 3) In DT test procedure, attention to observe the related parameters: Ec/Io, Rx Power, Tx Power,

Tx-Adj, FFER and this can help to understand the possible problem of network in time;4) Attention the environment geography change in test:

5) If there is sudden drop call, origination failure or handoff failure, write down the position and

go back here to teat again after all DT test, this is better to accumulate data for analyzing;

6) In test procedure, if than abnormal things happen, like replacing handset battery and notebook battery or other things, it is better to process in the same place, in order to keep the test data

integrity.

5. DT data analyzing After test, the right analyzing for test data is the key and this analyzing also can reflect theoptimization engineer technical level very much. According to the data analyzing with software,

the network coverage quality and problem can be found and then the adjustment scheme will be

decided to solve and improve the problem; The detailed analyzing procedures will be discussednext.

6. Decide adjustment scheme According analyzing result, decide adjustment scheme. For the concrete problem, there may be

several schemes to select. List them in priority;

7. Adjustment scheme implement Give the scheme to operator to implement. Because the adjustment is very important, so

optimization engineer should take part in implementation if necessary.



8. Validate DT test Judge if the adjustment is effective according to validate test;

9. Judge if the requirement is satisfied. According to validate test result, judge if the original optimization requirement is satisfied, or

locate the problem reasons and then write the optimization report, the optimization project is

finished; If can not, the new adjustment scheme should be decided or analyze the test data again,

DT Test Analyzing Application in

Optimization,coverage analyzing and

How to evaluate network coverageperformance

DT test application in coverage analyzing According DT test, the following data can be got and they can be used as coverage performance parameters:

· The strongest pilot strength (Ec/Io dB):

- MS Rx power (dBm): the total power received by MS inside 1.23MHz bandwidth including

interference.

· MS Tx power (dBm): MS transmitting power in calling or access statate.· MS Tx-Adj (dB): MS adjustment parameter in transmitting power. For 800MHz system,

TxPwr= -73 – RxPwr +Tx-Adj; For 1.9GHz system, TxPwr= -76 – RxPwr + Tx-Adj

· F- FER (%): Forward frame error rate

How to evaluate network coverage performance with DT test data

Single index analyzing

1. MS received power (RxPwrdBm) MS received power is one index to measure forward link coverage deepness.

MS received sensitivity is -105dBm, consider 5dB edge coverage margin, for different

environment DT test data should satisfy the following requirement:Rx Power > -100dBm is the range for outdoor coverage;

Rx Power > -85dBm is the range for indoor coverage;

Rx Power > -80dBm is the range for dense indoor coverage;

2. MS transmitting power (TxPwrdBm) MS transmitting power is one index to measure reverse link coverage deepness.

MS maximum Tx power is 23dBm, consider 5dB edge coverage margin, for different



environment DT test data should satisfy the following requirement:

Tx Power < 18dBm is the range for outdoor coverage;

Tx Power < 3dBm is the range for indoor coverage;Tx Power < -2dBm is the range for dense indoor coverage;

3. The strongest pilot (Ec/IodB) Pilot Ec/Io is one important index to measure forward link coverage performance. Usually the

cell threshold is >-15dB. In order to guarantee reliable demodulation, the maximum pilotthreshold need >-13dB. Pilot power ratio usually can not be changed.

4. MS (Tx-AdjdB) Tx_Adj reflects closed-loop power control adjustment. Usually, Tx_Adj range should be 0~-

10dBm. Too high or too low Tx_Adj value are all abnormal phenomena and indicate forwardand reverse link are not balanceable. Too low Tx_Adj indicates reverse link is better than

forward link, or reverse link initial power is too high; too high Tx_Adj indicates forward link is better than reverse link, or there is reverse interference.

5. Forward frame error rate (Fwd FER %) Forward FER reflects forward link coverage integrated quality. In CDMA system, the idealobjective FER is about 1% for 8K voice service. For data service the FER can be a little high.

The actual objective should be adjusted by operators’ requirement. For voice service, FER

increase will lead to bad voice quality. In coverage edge area, because of bad signal, FER may behigh.

Integrated analyzing Use Tx, Rx and Ec/Io to evaluate coverage ratio:

Urban DT test: calculate the average result for test data in 0.1km*0.1km Bin and get the average

Tx, Rx and strongest Ec/Io. Record the total Bin ratio that can satisfy Tx<=3dBm, Rx>=-85dBmand Ec/Io>-12dB simultaneously, that is the integrated coverage ratio.

Main roads DT test: directly use test data to calculate the ratio: Tx<=3dBm, Rx>=85dBm and

Ec/Io>-12dB, then combine them to get the integrated coverage ratio.

The popular optimization methods to

improve coverageThe popular optimization methods to improve coverage 1. Adjust antenna azimuth, down tilt, height;2. Replace antenna type and adjust antenna gain, beam width, adopt electric-down tilt antenna;

3. Adjust cell power;

4. Clear out outside interference;



5. Add new BTS or radio-remote station or repeater;

6. Add indoor distribution system;

7. Move BTS and adjust network topology structure;

DT Test Analyzing Application in Call Failure

MS calling principle MS call includes out-going call and in-going call; they are all included to “origination

procedure”.

One subscriber dials another subscriber; it is called as one origination. If the connection betweentwo subscribers can not be setup in defined time, it is called as “one origination failure”.

For example: MS voice out-going call. Its call procedure is shown as Fig

The signal procedure is like the following:



During the call procedures, if any one step is not finished, the call will be failed.

Integrated Analyzing Call successful ratio is used for network integrated evaluation. Increase successful ratio will

increase subscribers’ confidence for network and network equipments utilizing ratio. Call

successful ratio includes origination successful ratio and termination successful ratio.

For the large-scale commercial network, call successful ratio observed from OMC is more

accurate; for the network without load or light load, DT test can be used to acquire call

successful ratio, adopt sequence call test in DT test.

Call successful ratio= (total call successful number/total call attempt number)*100%

Commonly for urban area, 98% is a good performance index; for rural area this index should be

a little low.

Attention: The concrete index for call successful ratio is finally decided by operator’s requirement.

Call failure reasons analyzing

Call failure caused by equipment problems Strictly speaking, equipment problems should be solved before network optimization, but

actually a lot of equipment problems are found in optimization.



Typical phenomena The problems are sudden: the previous network works normally, and the problems happen

suddenly.The problems are universal: after DT test, it can be found that the problems happen in large area.

Analyzing:

Inquire if there is hardware changing recently, like boards replacing or transmission changingand so on; Inquire if there is software changing recently, like the software version updating or parameters adjustment;

If there are software and hardware adjustment, check the adjustment and consider resuming these

adjustments, observe if the problem will happen;

If there is no adjustment recently, start single cell checking and judge if there is problem in

hardware;

Single cell checking can find the obvious equipment problem, but some secluded problems arehard to find. At this time, boards resetting and replacement can be used to locate the problem.

Solution: Because the reason is equipment problem, so the solution can not be called as “optimization”, itis just like troubleshooting.

In troubleshooting, TRX, CHM, CCM, and antenna feeder system are the key points we should

care for.

Note: The operation for software and hardware should be very cautious. For commercial network, the

operation should be carried out by operator’s engineers after operator’s permission; All the operation for equipment should be after midnight, if there is problem in operation,everything should be resumed in time.

Call failure caused by poor coverage

Typical case: MS Rx power is about -100dBm or less;

MS Tx power tends to 23dBm;The strongest pilot Ec/Io is <-15dB;

After MS sends origination message, it is hard to access successfully, finally it is shown: call

failure;

Analyzing: MS call failure caused by poor coverage is normal phenomenon. In the edge of coverage, MS

receive power is very low and usually Rx power is about -100dBm or less, the strongest pilotEc/Io is -15dB or less; MS Tx power will tend to the maximum 23 dBm.



When MS starts origination in the edge of coverage, the signal transmission between BTS and

MS can not be received correctly for the bad air link and the call will be failed.In addition, even if MS starts origination in good coverage area, it will take some time to access

for MS. When MS moves fast to outside or cell (cars or railway stations), MS may have reached

outside of the coverage before access completion, this will lead to call failure.

Note: In CDMA protocol MS maximum Tx power is 23dBm (0.2W). But MS is produced by different

manufactures; the real maximum Tx power may exceed 23 dBm in practice.

Optimization solution: The ultimate way for this kind of problem is add new BTS or repeater in blind coverage area or

poor coverage area.

If adding new BTS is not possible, other methods also can be used to improve coverage, like

increase antenna height, select large gain antenna, and adjust antenna azimuth and down tilt. Butthese methods can not solve problems ultimately, and it should be very careful when change

these parameters.

CDMA Call failure caused by wireless link

fading and

Call failure caused by forward and reverse imbalance

Call failure caused by wireless link fading Typical case: In the beginning of origination, MS forward and reverse signal are normal, but finally the call is

failed;In this period MS received signal fades greatly ( MS is in the corner of street or goes into

subway).

Analyzing: When MS is in the corner of the street or goes into subway, the radio environment will change

greatly and signal fade very fast. Usually both forward and reverse link will fade at the sametime. If MS starts access at this time, it is very possible to meet access failure for signal losing.

Note:

For the signal losing, MS and BTS sides will transmit again. If the fading time is short, access procedure can be continued; but if the fading time is too long, the retransmitted signal may be

lost and the access will be failed.



Solution: Optimize network topology structure and decrease the area where signal fades greatly.

Call failure caused by forward and reverse imbalance

Typical case: MS received power and strongest pilot Ec/Io maintain in good state, such as Rx Power>-

100dBm, Ec/Io>-15dB;After MS origination, reverse Tx power is increasing continuously, until 23dBm, but access is

failed;

After access failure, MS will stay in previous pilot;

When MS is nearer to BTS, MS call can be successful. Observe Tx_Adj, it is a positive value.(Note: only when MS acquires F-TCH and reverse closed-loop power control starts working,

Tx_Adj value will be efficient)

Analyzing: In the above case, MS Rx power and pilot Ec/Io are all good, and this means the forward link isgood. But in MS origination procedure MS is increasing transmitting power until maximum, andthis means the reverse link is bad.

That is forward and reverse imbalance. Tx_Adj>0 also means forward is better than reverse.

Because forward is better than reverse, so in the edge of coverage BTS can not receive the signal

from MS correctly and call is failed.

Optimization method: Find the rootstock of imbalance:

Judge if the cell power configuration is too high:

Judge if the pilot gain is too high:

Judge if there is reverse interference;

Some analyzing when MS termination call is

not successfulSome analyzing when MS termination call is not successful

Typical case: Originated MS signal is normal;Originated MS finally can here voice record: “the number you dialed is not reachable”.



Analyzing: Commonly the reason may be the following:The terminated MS is not in service area or the signal coverage is poor;

The terminated MS just crosses LAC and does not start location update registration;

The terminated MS is just in idle handoff state.In order to confirm which reason causes the problem, need analyze the condition and locate the problem.

Acquire if the terminated MS is in coverage area and judge if the reason is MS has moved over

coverage area or signal is too bad;Acquire if the terminated MS is in the border of two LACs, judge if the reason is MS does not

make registration in time (Signal tracing can be used to analyze), usually one city should be

assigned only one LAC area, except for very big city;

If the above two cases can be excluded, it is very possible that MS is just in idle handoff and cannot be terminated successfully.

In IS-95A 6.6.2.1.4.2 protocol:

In idle handoff, MS will go into non-slot mode. After idle handoff, MS will throw away all themessages from the old BTS, which has not been processed. This means: when BTS sends paging

message to MS, MS is just in idle handoff and MS can not receive the message correctly;

furthermore, even if MS has received the message, it can still not send paging response. These

two cases will lead that MS can not be terminated successfully.

This is why we often meets the case: the first dialing to other MS, we will hear voice record: “the

number you are dialing is not reachable” (because MS is just in idle handoff); but the second

dialing will be successful (because MS has finished idle

handoff).

Note: System not support access handoff also can cause terminated call failure. When MS is paged

successfully and MS is just moving from the current cell to another cell, MS will access failure because the system does not support access handoff and the current cell pilot fades too fast.

In this case, MSC side often sends voice record to origination MS like: “The network is busy

now, please redial later”. Certainly different operators may send different voice records.

Optimization method: If the reason is coverage, it is normal;If the reason is crossing LAC, check LAC planning. Usually the border of LAC should be set in

the low traffic area;

If the reason is idle handoff, it is normal phenomenon. If the problem is very heavy,

consider adjusting the network topology structure and changing idle handoff area.



Drive Test Application in Call Drop

Analyzing

Drive Test Application in Call Drop AnalyzingCall drop is the interruption of call and it is caused by BTS or MS releasing traffic channel

without user permission.

Call drop mechanismCDMA system is a closed-loop system, the closed-loop signal link is very necessary between

BTS and MS in data or voice transmission. Some important process, like power control and

handoff, all need one closed-loop link. If this link is broken for any reason, MS will lose control

and need initialization again and go back to idle state. When closed-loop signal link is broken,call drop mechanism will be started. Closed-loop signal link includes forward link and reverse

link, any one link is broken can cause call drop.

1 MS drop mechanism

1. MS bad frame If the mobile station receives N2m consecutive bad frames on the Forward Traffic Channel, itshall disable its transmitter. Thereafter, if the mobile station receives N3m consecutive good

frames, the mobile station should re-enable its transmitter.

(Extracted from 95 standard 6.4.4) In 95 standards, N2m is defined as constant 12; N3m is

defined as constant 2.

2. MS fading timer The mobile station shall establish a Forward Traffic Channel fade timer. The timer shall be

enabled when the mobile station first enables its transmitter when in the Traffic Channel

Initialization Sub state of the Mobile Station Control on the Traffic Channel State. The fadetimer shall be reset for T5m seconds whenever N3m consecutive good frames are received on the

Forward Traffic Channel. If the timer expires, the mobile station shall disable its transmitter and

declare a loss of the Forward Traffic Channel. (Extracted from 95 standard 6.4.4) In 95standards, N3m is defined as constant 2; T5m is defined as constant 5s.

3. MS acknowledgment failure If the mobile station has not received an acknowledgement within T1m seconds after

transmitting the message, the mobile station shall retransmit the message. (Extracted from 95

standard 6.6.4.1.3.1.1) The mobile has N1m attempts to transmit a message that requiredacknowledgment. If the mobile does not receive the acknowledgement T1m seconds after the

N1m time, the mobile declares an acknowledgment failure. In 95 standards, N1m is defined as

constant 3; T1m is defined as constant 0.4s.



2 BTS call drop mechanism

1. BTS bad frame when FER reaches to 90% in 100 frames and this happens 3 times consecutively, BTS will

release the links.

2. BTS acknowledgement There 9 times for BTS acknowledgement, and the waiting time between two acknowledgementsis 0.4s.

Integrated analyzing Call drop ratio can be used to evaluate network integrated performance. Call drop ratio

improvement can decrease subscribers’ complaints and increase their satisfaction. For the large

scale commercial network, call drop ratio observed from background OMC is more accurate andimpersonal; for unloaded or light-load network, it can be got by DT test. In DT test, the call

mode adopts “sequence call test”, call drop ratio is defined as: call drop number/total successfulcall number; if adopts “long call test”, total successful call number is total calling time (s)/90.

For urban area, call drop ratio is less than 0.8% means network performance is good; for suburbor roads coverage, this index can be a litter low.

CDMA Call failure caused by unsuitable

access parameters

Call failure caused by unsuitable access parameters

Typical case: MS Rx power is normal and pilot Ec/Io is normal;

Observe MS received signal messages in DT test, MS does not receive BTS ACK message after

MS starts origination, then finally the access is failed;In this period MS Rx power is normal, there is no large fading;

But MS Tx power is not high before access failure:

Analyzing: According to call procedure principle, when BTS receives MS access request, BTS will send

ACK message to MS. In above cases, MS does not receive BTS ACK message, this is the mainreason for call failure.

MS does not receive ACK message, two possibilities:

1. BTS does not receive MS access request;2. BTS has sent ACK message, but MS does not receive.

For the second, usually the reason is large fading in forward link and MS can not receive the

message. According to DT test, if there are no large fading phenomena, this reason can be



excluded.

For the first reason, according to DT test, it is very possible. There are also two possibilities:

There is large fading or strong interference in reverse link; In this case, MS Tx power will tendto maximum and it can be solved;

Access parameters setting are not suitable and access problem power is too low, so access

request can not be received correctly.

The related parameters are like the following:

INIT_PWR Definition: Initial power, the correction factor used by the mobile stations in the open-loop

power estimation for initial transmission on an access channel expressed as a binary complementvalue in units of 1 dB

Range: -16~~15dB, default value is 0dB;

Note: High INIT_PWR value is better for access channel acquisition, but increases reverse

interference; low INIT_PWR will make access channel acquisition become difficult.

NOM_PWR Definition: Nominal transmit power offset, BTS use this parameter as correction factor for open-

loop power control, expressed as a binary complement value in units of 1 dBRange: -8~~7dB, default value is 0dB;



PWR_STEP Definition: Power increment, the value by which mobile stations increase their transmit power between successive probes in an access probe sequence, in units of 1 dB.

Range: 0~~7dB

NUM_STEP Definition: Number of access probes. This parameter is one less than the maximum number of access probes that mobile stations are to transmit in a single access probe sequence.

Range: 1~~15dB, default value is 6

Note: high NUM_STEP value can increase access probability, but also can increase access time;

low NUM_STEP value will decrease access probability.

MAX_REQ_SEQ

Definition: The maximum number of access probe sequences for an access channel request. Thevalue must be greater than 0.

Range: 1~~15, default value is 2 Note: high MAX_REQ_SEQ value can increase access probability, but also can delay access

time; low MAX_REQ_SE value will decrease access probability, but decrease access time.

MAX_RSP_SEQ Definition: The maximum number of access probe sequences for an access channel response.

The value must be greater than 0.Range: 1~~15, default value is 2

Note: high MAX_ RSP _SEQ value can increase access probability, but also can delay accesstime; low MAX_ RSP _SEQ value will decrease access probability, but decrease access time.

Note: To confirm if BTS receives access request or sends ACK message, the best way is to start signaltracing for this MS.

Optimization method: Check background parameter setting and adjust access parameters.

cdma drive test and optimization.docx

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