CDMA Call Processing_Excellent

7/27/2019 CDMA Call Processing_Excellent

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CDMA CALL PROCESSING


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To process a call, MS goes through theTo process a call, MS goes through the

following stages to get traffic channel.following stages to get traffic channel.

SYSTEM INITIALISATION STATESYSTEM INITIALISATION STATE

SYSTEM IDLE STATESYSTEM IDLE STATE SYSTEM ACCESS STATESYSTEM ACCESS STATE

TRAFFIC CHANNEL STATETRAFFIC CHANNEL STATE


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Tune to CDMA Carrier

Mobile acquires pilot channel and sync channel

Mobile acquires paging channel and monitors for messages

Mobile sends messages on access channel, BS sendsmessages on paging channel.

Speech communication on forward and reverse trafficchannel, Power control on forward link

System initialization state

Idle state

Access State

Traffic channel state

CALL PROCESSING


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CALL PROCESSING STATE:CALL PROCESSING STATE:

In system initialization state the mobileIn system initialization state the mobileacquires a pilot channel by searching the PN offacquires a pilot channel by searching the PN off

sets and selects the strongest pilot signal.sets and selects the strongest pilot signal. Then it acquires synchronization channel usingThen it acquires synchronization channel using

WW3232 and detecting timing offset of pilotand detecting timing offset of pilot

channel. Then mobile acquires the systemchannel. Then mobile acquires the systemconfiguration and timing information.configuration and timing information.

hen the MS enters the system idle state wherehen the MS enters the system idle state whereit monitors the paging channel. Now the mobileit monitors the paging channel. Now the mobilecan receive necessary message to initiate orcan receive necessary message to initiate or

receive a call.receive a call.


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If a call is placed or received, MS enters theIf a call is placed or received, MS enters thesystem access state exchanging necessarysystem access state exchanging necessaryparameters. MS transmits its response onparameters. MS transmits its response on

access channel and BS transmits on pagingaccess channel and BS transmits on pagingchannel.channel.

On access, the MS enters traffic channelOn access, the MS enters traffic channelstate and communicate. It also transmitsstate and communicate. It also transmitscontrol messages replacing speech bycontrol messages replacing speech by

signaling.signaling.

Power control messages are sent on forwardPower control messages are sent on forwardlink channel.link channel.


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SYSTEM INITIALIZATION STATESYSTEM INITIALIZATION STATE

Power up andmobile enters

initialization state

Systemdeterminationsub state

Pilotacquisitionsub state

Sync channelacquisitionsub state

Timingchange substate

CDMAsystem isselected

Pilot channel isacquired

Sync channelis acquired

System timingis acquired

Enter idlestateAnalog

initialization

Begin analogmode


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System determination sub state :System determination sub state :

Mobile can select analog or CDMA, if theMobile can select analog or CDMA, if thesystem selects CDMA, the mobile sets thesystem selects CDMA, the mobile sets theCDMA channel parameters to channelCDMA channel parameters to channel

number.number. Pilot channel acquisition sub state:Pilot channel acquisition sub state:

Mobile acquires pilot channel of CDMAMobile acquires pilot channel of CDMA

system and tunes to CDMA channel and setssystem and tunes to CDMA channel and setsits code channel for the pilot channel andits code channel for the pilot channel andsearches for pilot channel within 20 msec, thesearches for pilot channel within 20 msec, the

mobile should acquire pilot channel, elsemobile should acquire pilot channel, elsemobile enters system determination sub statemobile enters system determination sub stateindicating failure.indicating failure.


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Synchronization acquisition sub state :Synchronization acquisition sub state :Mobile acquires the sync channel andMobile acquires the sync channel and

obtains system configuration and timingobtains system configuration and timinginformation for CDMA system and sets itsinformation for CDMA system and sets itscode channel for sync channel if mobile doescode channel for sync channel if mobile doesnot receive a sync channel message withinnot receive a sync channel message within21 msec, mobile enters the sync21 msec, mobile enters the sync

determination sub state with a protocoldetermination sub state with a protocolmismatch indication.mismatch indication.

If it receives within 21 msec, mobileIf it receives within 21 msec, mobilestores system configuration and timingstores system configuration and timinginformation.information.


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Timing change sub state :Timing change sub state :If a mobile synchronizes its long codeIf a mobile synchronizes its long code

timing of system timing to those of CDMAtiming of system timing to those of CDMA

system after receiving and processing syncsystem after receiving and processing sync

messages.messages.

After sync channel is acquired and syncAfter sync channel is acquired and syncmessage is received, it stores themessage is received, it stores the

following information like systemfollowing information like system

identification, network identification,identification, network identification,system time, long code at system time,system time, long code at system time,

paging channel data rate etc..paging channel data rate etc..


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CDMA initialization

Acquires primary paging

channel (W1)

monitors paging channel

Authentication

Idle hand off

Page Response

Mobile origination

Receives an incoming call

Registration

Idle StateIdle State


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Idle State :Idle State :Mobile monitors paging channel.Mobile monitors paging channel.

Mobile can receive messages from baseMobile can receive messages from base

station to initiate or receive a call.station to initiate or receive a call.It can also initiate a registrationIt can also initiate a registration

process, message transmission. Afterprocess, message transmission. After

entering idle state, mobile sets its Walshentering idle state, mobile sets its Walshcode to the primary paging channel andcode to the primary paging channel andsets its rate to the rate obtained from syncsets its rate to the rate obtained from sync

message.message.Paging channel is subdivided into 80Paging channel is subdivided into 80

msec slots are called paging channel slots.msec slots are called paging channel slots.


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InIn slotted modeslotted mode, the mobile monitors only, the mobile monitors onlycertain assigned slots. When pagingcertain assigned slots. When paging

channel is not monitored, mobile can stopchannel is not monitored, mobile can stopor reduce its processing activities to saveor reduce its processing activities to save

battery power.battery power.

In theIn the non slotted modenon slotted mode, paging and, paging andcontrol data can be received on any of thiscontrol data can be received on any of this

slot. The mobile monitors all the slots onslot. The mobile monitors all the slots on

continuous basis.continuous basis.


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Idle Hand off :Idle Hand off :

Idle hand off or change of paging channelIdle hand off or change of paging channeloccurs when a mobile has moved fromoccurs when a mobile has moved fromcoverage of one base station to coverage ofcoverage of one base station to coverage of

another, during idle state. Hand off shouldanother, during idle state. Hand off shouldoccur when it detects new pilot that is strongeroccur when it detects new pilot that is strongerthan current pilot.than current pilot.

Pilots are identified by short PN offsets.Pilots are identified by short PN offsets.These pilot sets are maintained by active,These pilot sets are maintained by active,candidate, neighbor, remaining. If neighborcandidate, neighbor, remaining. If neighbor

set or remaining set is stronger than active setset or remaining set is stronger than active setand candidate set, pilot hand off is performed.and candidate set, pilot hand off is performed.On receiving new message, from new pagingOn receiving new message, from new pagingchannel, it resumes operations.channel, it resumes operations.


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SYSTEM ACCESS STATE:SYSTEM ACCESS STATE:

It includes following sub states.It includes following sub states.

1.1. Update overhead informationUpdate overhead information2.2. Mobile State origination AttemptMobile State origination Attempt

3.3. Page ResponsePage Response4.4. Registration Access sub stateRegistration Access sub state

5.5. Mobile Station TransmissionMobile Station Transmission


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Traffic channel sub state:Traffic channel sub state:

Speech communication takesSpeech communication takesassociated with control messages.associated with control messages.

There are 5 sub states in this.There are 5 sub states in this.

1.1. Traffic Channel initialization :Traffic Channel initialization :

In this state, mobile verifies it canIn this state, mobile verifies it can

receive forward traffic channel and startsreceive forward traffic channel and startstransmit on reverse link.transmit on reverse link.

2.2.

Waiting for order sub state:Waiting for order sub state:

In this, MS waits for an alert withIn this, MS waits for an alert with

information message.information message.


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3.3. Waiting for MS answer sub state:Waiting for MS answer sub state:

In this state, the MS waits for user toIn this state, the MS waits for user to

answer the call.answer the call.4.4. Conversation sub state:Conversation sub state:

Here, the MS exchange primary trafficHere, the MS exchange primary traffic

data packets with base station.data packets with base station.

5.5. Release Sub state:Release Sub state:

In this case, MS disconnects a call.In this case, MS disconnects a call.


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CDMA REGISTRATIONCDMA REGISTRATION

Registration is a process in which theRegistration is a process in which the

MS tells the base station about theMS tells the base station about thewhereabouts. It notifies base station ofwhereabouts. It notifies base station of

its location status, identification, slot cycleits location status, identification, slot cycle

and other characteristics.and other characteristics.Purpose of registration is to enable thePurpose of registration is to enable the

base station to page the mobile in case ofbase station to page the mobile in case of

an incoming call.an incoming call.


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CDMA supports 9 types of registration.CDMA supports 9 types of registration.

1.1. Power up registration :Power up registration : The mobile registers,The mobile registers,when it powers up.when it powers up.2.2. Power down registration :Power down registration : The mobileThe mobile

registers, when it powers down informing theregisters, when it powers down informing thesystem that it is no longer active.system that it is no longer active.

3.3. Time based registration :Time based registration : the mobile registersthe mobile registersat regular intervals of time. Its use also alerts theat regular intervals of time. Its use also alerts thesystem to automatically deregister mobile stationssystem to automatically deregister mobile stationsthat did not perform a successful power downthat did not perform a successful power downregistration.registration.

4.4. Distance based registration :Distance based registration : Mobile performsMobile performsa registration when distance between currenta registration when distance between currentbase station and the base station which it hasbase station and the base station which it hasprevious registered exceeds the threshold.previous registered exceeds the threshold.


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5. Zone based registration :5. Zone based registration : Mobile registers when itMobile registers when it

enters a new zone.enters a new zone.

6. Parameter changed registration :6. Parameter changed registration : Mobile does aMobile does aregistration when it enters a new system or some ofregistration when it enters a new system or some ofits stored parameters change.its stored parameters change.

7. Ordered registration :7. Ordered registration : mobile registers when amobile registers when abase station asks for it.base station asks for it.

8. Implicit registration :8. Implicit registration : When a MS sends aWhen a MS sends a

successful origination message or page responsesuccessful origination message or page responsemessage, base station can ask a mobile of its location.message, base station can ask a mobile of its location.

9. Traffic channel registration :9. Traffic channel registration : Base station tellsBase station tells

the mobile, it is registered.the mobile, it is registered.Only power up, power down, time based,Only power up, power down, time based,

location based registrations are presentlylocation based registrations are presentlysupported.supported.


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CALL PROCESSING (Mobile Station to Base Station)

Sends origination message Receives origination messageAccess Channel

Receive Paging Channel Sets up Traffic Channel, startssending null traffic data

Paging Channel

Sets up reverse traffic chAcquires reverse traffic Ch

Rev traffic ChStarts sending Traffic Chpreamble

Fwd traffic ChReceives Ack from BS

Starts sending null trafficdata

Rev traffic Ch

Sends BS Acknowledgement

Receives data from Mobile

Sends originationcontinuation message

Rev traffic Ch Receives the message

Receives ring back tone Fwd traffic Ch Sends Alert with info msg

Ring Stops Fwd traffic Ch Called subscriber answers, alerttone off.

Conversation ConversationFwd/Rev traffic Ch

Mobile originated call

MS BTS


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CALL PROCESSING (Base Station to Mobile Station)

Sends page message Receives page messagePaging Channel

Receive Paging Response Sends paging Responsemessage

Access Channel

Sets up traffic chReceives traffic data frames

Paging ChStarts sending null Trafficdata

Rev traffic ChSends channel assignment

Acquires rev tfc ch sendsbs ack order

Fwd traffic Ch

Sets up reverse traffic ch, sendstraffic channel preamble

Process primary traffic data

Sends alert with info msg Fwd traffic Ch Starts ringing, user answers,stops ringing

Receives connect order Rev traffic Ch Sends connect order

Conversation ConversationFwd/Rev traffic Ch

Mobile Terminated callBS MS


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Mobile initiated call disconnect

MS

Detects user initiated , sends Release order

Enters system determination sub state, ofmobile station initialization state

Sends releaseorder

Rev Tfc Ch

Fwd Tfc Ch

BS


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Base Station initiated call disconnect

BS

Detects user initiated ,

sends Release order

Enters system determination

sub state, of mobile station

initialization state

Fwd Tfc Ch

Rev Tfc Ch

MS


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CALL PROCESSING DURING SOFT HAND OFF

Mobile Station Base Station

< User conversation using A > < User conversation using A >

Pilot B level exceeds T_ADDsends pilot strengthMeasurement Report

A receives measurementreport, B starts sending data

Receives hand off direction

message ( Starts using activeset A&B)

acquires reverse traffic

channel, A and B send hand offdirection message to use A&B

Sends hand off completion

message

A&B receive completion

messageHand off drop timer for pilot A

expiresA&B receive measurement

report

Continued.

RTCH

RTCH

RTCH

FTCH


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CALL PROCESSING DURING SOFT HAND OFF

Mobile Station Base Station

Mobile sends measurementreport

A&B send hand off directionmessage to use pilot B only

Receives hand off directionmessage

Sends hand off completion

message

A&B receive completion message

A stops transmitting on fwd chand receiving on rev traffic channel

< User conversation using B > < User conversation using B >

RTCH

FTCH

RTCH

F/RTCH

Documents

CDMA Call Processing_Excellent