FACCH Call Set-up

FACCH Call Set-up

dn9814074Issue 7-0 en

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2003330Nokia BSC S10.5 ED, Vers. 2, ProductDocumentation

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FACCH Call Set-up

Contents

Contents 3

List of tables 4

List of figures 5

Summary of changes 7

1 Introduction to FACCH Call Set-up feature 91.1 FACCH Call Set-up overview 9

2 Functional properties of FACCH Call Set-up 112.1 FACCH Call Set-up user interface 112.2 FACCH Call Set-up and mobile access 12

3 Channel required procedure of FACCH Call Set-up 153.1 Detailed description of channel required procedure of FACCH Call Set-

up 15

4 Channel reservation procedure of FACCH Call Set-up 19

5 Channel activation procedure of FACCH Call Set-up 215.1 CHANNEL_ACTIVATION message 215.2 CHANNEL_ACTIVATION_ACKNOWLEDGE message 22

6 Immediate assignment procedure of FACCH Call Set-up 256.1 IMMEDIATE_ASSIGN_COMMAND message 256.2 IMMEDIATE_ASSIGNMENT, SABM, UA messages 266.3 ESTABLISH_INDICATION message 27

7 Mode modify procedure of FACCH Call Set-up 297.1 ASSIGNMENT_REQUEST message 307.2 MODE_MODIFY in the BSS 327.3 CHANNEL_MODE_MODIFY in the BSS 33

Glossary 35



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Contents

List of tables



FACCH Call Set-up

List of figures

Figure 1. CHANNEL REQUIRED procedure 15

Figure 2. CHANNEL_REQUEST message, only one octet long 16

Figure 3. CHANNEL ACTIVATION procedure 21

Figure 4. IMMEDIATE ASSIGNMENT procedure 25

Figure 5. MODE MODIFY procedure 29



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List of figures



FACCH Call Set-up

Summary of changes

Summary of changes

Changes between document issues are cumulative. Therefore, the latest documentissue contains all changes made to previous issues.

Changes made between issues 7 and 6

No major changes, only a note about AMR and FACCH Call Set-up added inchapter Introduction to FACCH Call Set-up feature .


MODE_MODIFY in the BSS

Multirate configuration <OPTION> added to MODE_MODIFY message.

CHANNEL_MODE_MODIFY in the BSS

Multirate configuration <OPTION> added to CHANNEL_MODE_MODIFYmessage.

The document has been revised throughout to comply with the latestdocumentation standards.


No modifications in content; consistency of concepts and references checked andcorrected.


Purpose of this function class

Removed information concerning phase 1 and phase 2 mobile stations.

References

Added References Dual Band GSM/DCS Network Operation and Half RateTelecom. Removed Reference ETR 09.09 Technical Report.

Detailed description

Added Figure 2: CHANNEL_REQUEST message. Added Tables 1 and 2: NECIparameter is set to OFF/ON.

Channel reservation procedure



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Summary of changes

Channel reservation principles changed.

Channel activation procedure

Field changes in channel_activation message due to half rate and dual band.

Mode modify procedure

New failure reasons and field changes due to half rate added in the procedure.

Sections removed:

FACCH call set-up and other features

Failure



FACCH Call Set-up

1 Introduction to FACCH Call Set-upfeature

This feature is optional. In FACCH call set-up, the MS is assigned from theCCCH to the TCH - instead of the SDCCH - with the IMMEDIATEASSIGNMENT procedure. The TCH is used for signalling and thus noassignment procedure is needed in the Radio interface. Instead, only the MODEMODIFY procedure to the TCH channel is required to change the channel modefrom signalling to speech.

When an MS requests a dedicated resource by sending a random access, the BSCtries to allocate a SDCCH for the MS. If there are no SDCCHs available at thatmoment the BSC tries to allocate a TCH instead of rejecting the resource request.If there are free TCHs, the FACCH call set-up is used. This means that FACCH isused instead of SDCCH for call set-up signalling and at the assignment phase ofthe call the channel mode is modified from signalling to, for example, speech.

Note

The BTS must support AMR, otherwise the AMR with FACCH Call Set-up doesnot work.

1.1 FACCH Call Set-up overview

The whole topic summary of FACCH Call Set-up

Functional properties of FACCH Call Set-up

Channel required procedure of FACCH Call Set-up

Channel reservation procedure of FACCH Call Set-up

Channel activation procedure of FACCH Call Set-up



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Introduction to FACCH Call Set-up feature

Immediate assignment procedure of FACCH Call Set-up

Mode modify procedure of FACCH Call Set-up



FACCH Call Set-up

2 Functional properties of FACCH Call Set-up

2.1 FACCH Call Set-up user interface

The network operator can set the FACCH call set-up for each BSC, via the man-machine interface (MMI).

Similarly, with the MMI the operator can set the NECI field for newestablishment cause values on or off for an individual cell

The parameters used are described below.

FACCH CALL SET UP

The network operator can activate or deactivate the whole FACCH Call Set-upfeature by using parameter FACCH call set up . This parameter can be operatedvia Parameter Handling MML. For more details, see Parameter Administration .It is also available in the NMS.

NEW ESTABLISHMENT CAUSES SUPPORT

The network operator can set the value of NECI field by using parameter newestablishment causes support . This parameter can be operated via BaseTransceiver Station Handling MML. For more details, see Radio networkadministration .

EMERGENCY CALL ON FACCH

The network operator can activate or deactivate the emergency call to useFACCH Call Set-up by using parameter emergency call on FACCH . Thisparameter can be found from radio network database and it can be operated viaBase Station Controller Handling MML. For more details, see Base StationController Handling in MSC (ED). It is also available in the NMS.



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RE-ESTABLISHMENT ON FACCH

The network operator can activate or deactivate the re-establishment to useFACCH Call Set-up by using parameter re-establishment on FACCH . Thisparameter can be found from radio network database and it can be operated viaBase Station Controller Handling MML. For more details, see Base StationController Handling in MSC (ED). It is also available in the NMS.

ORDINARY CALLS ON FACCH

The network operator can activate or deactivate the mobile originating call to useFACCH Call Set-up by using parameter ordinary calls on FACCH . Thisparameter can be found from radio network database and it can be operated viaBase Station Controller Handling MML. For more details, see Base StationController Handling in MSC (ED). It is also available in the NMS.

ANSWER TO PAGING CALL ON FACCH

The network operator can activate or deactivate the mobile terminated call to useFACCH Call Set-up by using parameter answer to paging call on FACCH . Thisparameter can be found from radio network database and it can be operated viaBase Station Controller Handling MML. For more details, see Base StationController Handling in MSC (ED). It is also available in the NMS.

2.2 FACCH Call Set-up and mobile access

The NECI field allows the mobile stations to use the new establishment causevalues. The field also shows the half rate support for the call. (see Half Rate inBSC ). When a mobile station requests a channel, the request can include moreaccurate information about the establishment cause and channel type needed forthe service requested.

The following calls and channel types are possible:

. emergency call (SDCCH or TCH/F)

. call re-establishment (SDCCH, TCH/F or TCH/H)

. answer to paging (SDCCH, TCH/F or TCH/H indicated by MS)

. mobile originating speech/data call (SDCCH, TCH/F or TCH/H)

. location updating (SDCCH)

. other procedures on SDCCH.



FACCH Call Set-up

The channel request values also include the indication of the suggested rate. TheBSC will allocate a suitable resource for a transaction according to the SDCCH orthe TCH.

The following channel request values can be set in the FACCH call set-up:

. emergency call

. answer to paging

. ordinary call

. re-establishment.



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FACCH Call Set-up

3 Channel required procedure of FACCHCall Set-up

The CHANNEL REQUIRED procedure offers the mobile station the means tostart the establishment of the mobile originating call or the answering to thePAGING REQUEST message.

The MS requests a dedicated signalling channel SDCCH with theCHANNEL_REQUEST message.

Figure 1 shows the CHANNEL REQUIRED procedure.

Figure 1. CHANNEL REQUIRED procedure

3.1 Detailed description of channel required procedureof FACCH Call Set-up

The MS requests access by sending the CHANNEL_REQUEST message (a) tothe BTS on the RACH. It is sent in random mode and consists of two differentinformation elements coded as follows:

MS BTS BSC MSC

a)CHANNEL REQUEST

b)CHANNEL REQUIRED



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Figure 2. CHANNEL_REQUEST message, only one octet long

The ESTABLISHMENT CAUSE information field indicates the reason forrequesting the establishment of a connection. This field has a variable length(from 3 bits up to 6 bits). The RANDOM REFERENCE is an unformatted fieldwith variable length (from 5 bits down to 2 bits). The ESTABLISHMENTCAUSE information field length is 3 when the MS is GSM phase 1 level or whenthe MS is GSM phase 2 level and the NECI parameter is set to OFF.

The following estbalishment causes are supported: (RANDOM REFERENCEfield is filled with 'x').

. NECI parameter is set to OFF:

MESSAGE MEANING OF ESTABLISHMENT CAUSE

8 .... 1

000xxxxx Other procedures (SDCCH).

100xxxxx Answer to paging. (SDCCH or TCH/F)

101xxxxx Emergency call. (SDCCH or TCH/F)

110xxxxx Call re-establishment. (SDCCH or TCH/F)

111xxxxx Originating call. (SDCCH or TCH/F)

. NECI parameter is set to ON:

MESSAGE MEANING OF ESTABLISHMENT CAUSE

8 .... 1

0000xxxx Location updating (SDCCH needed).

0001xxxx Other procedures which can be completed

with an SDCCH.

100xxxxx Answer to paging. (SDCCH or TCH/F)

101xxxxx Emergency call. (SDCCH or TCH/F)

110xxxxx Call re-establishment (SDCCH or TCH/F)

Bit 8 7 6 5 4 3 2 1

Octect 1ESTABLISHMENT RANDOM

CAUSE REFERENCE



FACCH Call Set-up

111xxxxx Originating call (SDCCH or TCH/F)

0010xxxx Answer to paging. Dual rate MS and TCH/F

is requested. (TCH/F or SDCCH)

0011xxxx Answer to paging. Dual rate MS and TCH/H

or TCH/F is requested. (TCH/H, TCH/F or SDCCH)

0100xxxx Originating speech call from dual rate MS

when TCH/H is sufficient. (TCH/H, TCH/F or

SDCCH)

0101xxxx Originating data call from dual rate MS

when TCH/H is sufficient. (TCH/H, TCH/F or

SDCCH)

011010xx Call re-establishment; TCH/H was in use

and the network sets NECI bit to 1.

(TCH/H, TCH /F or SDCCH)

The network uses the random reference and the MS access slot number to identifyand to address the MS.

The MS starts the GSM timer T3120 and waits for its access acceptance, which isthe IMMEDIATE_ASSIGNMENT message on the AGCH.

If the MS access is not granted within the time limit defined by the T3120, theMS makes a second attempt, sending another CHANNEL_REQUEST messagewith a new random reference on the next time slot. A new value of the GSMtimer T3120 is computed and used. The MS repeats this procedure either until itis granted access or until the number of repetitions reaches the maximum.

CHANNEL_REQUIRED message

After receiving the CHANNEL_REQUIRED message (b), the BSC starts toallocate a relevant channel.

The CHANNEL_REQUIRED message from the BTS includes the followingdata:

. message discriminator: common channel management

. message type: channel required

. channel number: uplink CCCH (RACH)

. request reference: establishment cause, random reference received in thechannel request and the frame number on which it was received

. access delay: delay of the access burst as measured by the BTS.



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FACCH Call Set-up

4 Channel reservation procedure ofFACCH Call Set-up

After receiving the CHANNEL_REQUIRED message, the BSC starts to searchfor a SDCCH channel. If there are no SDCCHs available the BSC starts to searchfor a TCH channel. If a TCH channel is available in the cell from which theoriginal access was granted, the BSC reserves it and the IMMEDIATEASSIGNMENT procedure starts.

The BSC can allocate TCH or SDCCH channels as follows:

. TCH/F or TCH/H channel due to the CHANNEL_REQUIRED message, ifthere are no SDCCHs available and the FACCH set-up is allowed

. SDCCH channel due to the CHANNEL_REQUIRED message, if there areSDCCHs available and the FACCH set-up is allowed

. SDCCH channel due to the CHANNEL_REQUIRED message, if theFACCH set-up is not allowed.

The number of TCH and SDCCH channels depends on the radio configuration.

If all the SDCCH and TCH channels are reserved in the cell, the BSC sends anIMMEDIATE_ASSIGNMENT_REJECT message to the MS.



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Channel reservation procedure of FACCH Call Set-up



FACCH Call Set-up

5 Channel activation procedure of FACCHCall Set-up

After a new TCH has been successfully reserved, the BSC activates the channelby sending the CHANNEL_ACTIVATION message to the BTS. The GSM timerT9103 supervises the channel activation procedure. The channel mode for theTCH channel is signalling .

If the BTS refuses to activate the new channel, it sends theCHANNEL_ACTIVATION_NACK message that includes the reason for thefailure to the BSC.

Figure 3 shows the CHANNEL ACTIVATION procedure.

Figure 3. CHANNEL ACTIVATION procedure

5.1 CHANNEL_ACTIVATION message

The BSC sends the CHANNEL_ACTIVATION message to the BTS in order toactivate the new TCH channel.

The CHANNEL_ACTIVATION message includes the following data:

. message discriminator: dedicated channel management

. message type: channel activation

MS BTS BSC MSC

a)CHANNEL ACTIVATION

b)CHANNEL ACTIVATION ACK



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. channel number

. activation type

. channel mode: DTX control and channel type (signalling, TCH/F or TCH/H, no resources required)

. channel identification: channel description and mobile allocation<OPTION>

. encryption information <OPTION>

. BS power: maximum BS power level authorised in the cell <OPTION>

. MS power: maximum MS power level authorised in the cell <OPTION>

. timing advance to be used by the MS in subsequent communications<OPTION>

. SACCH_INFORMATION <OPTION>.

When the Abis interface is on the GSM phase 2 level, channel identification isnot used. Encryption information is present if needed. SACCH information isused in dual band cell (see Basic Call ). Other optional elements are alwayspresent.

5.2 CHANNEL_ACTIVATION_ACKNOWLEDGEmessage

A successful activation is acknowledged by the BTS with theCHANNEL_ACTIVATION_ACK message. The BTS starts the transmission andreception on the associated SACCH, using the power levels and the timingadvance received in the CHANNEL_ACTIVATION message.

The BTS acknowledges a failure with the CHANNEL_ACTIVATION_NACKmessage. The following failure cases are possible (see ETS 300 596 (GSM08.58)):

. radio resource not available

. radio channel already activated or allocated

. protocol error and subclause, such as mandatory information error

. O&M intervention when the channel cannot be used for O&M reasons

. encryption algorithm not implemented

. equipment failure



FACCH Call Set-up

. service or option not available

. not implemented unspecified

. mandatory IE error

. general IE error.

If the BSC does not receive the CHANNEL_ACTIVATION_ACK orCHANNEL_ACTIVATION_NACK message within the time limit of the GSMtimer T9103, or if it has received the CHANNEL_ACTIVATION_NACKmessage, it releases the allocated channel and sends anIMMEDIATE_ASSIGNMENT_REJECT message to the MS.



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FACCH Call Set-up

6 Immediate assignment procedure ofFACCH Call Set-up

The IMMEDIATE_ASSIGN message enables the MS to assign onto a TCHchannel, whereas the IMMEDIATE_ASSIGN_REJECT message refuses to grantthe MS access. The GSM timer T3101 supervises the immediate assignmentprocedure.

If the TCH channel reservation or activation has failed, the BSC sends theIMMEDIATE_ASSIGN_REJECT message to the MS.

Figure 4 shows the IMMEDIATE ASSIGNMENT procedure.

Figure 4. IMMEDIATE ASSIGNMENT procedure

6.1 IMMEDIATE_ASSIGN_COMMAND message

After a successful TCH channel activation, the BSC sends theIMMEDIATE_ASSIGN_COMMAND message (a) to the BTS. This messagecontains the IMMEDIATE_ASSIGN message, which the BTS sends to the MS.

The IMMEDIATE_ASSIGN_COMMAND message includes the following data:

MS BTS BSC MSC

a)IMMEDIATE ASSIGN COMMAND

b)IMMEDIATE ASSIGN

SABM c)d)ESTABLISH INDICATION

e)UA



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. message header

. message type

. channel number

. immediate assignment information.

IMMEDIATE ASSIGNMENT information contains the completeIMMEDIATE_ASSIGNMENT message:

. message header

. page mode: normal paging

. channel description of the TCH allocated, the associated SACCH andfrequency or hopping sequence

. request reference as sent by the MS in the channel request

. initial timing advance

. mobile allocation if frequency hopping is used

. rest octet only for phase 2.

6.2 IMMEDIATE_ASSIGNMENT, SABM, UA messages

After receiving the IMMEDIATE_ASSIGNMENT message, the MS tunes to theassigned TCH and starts to establish the signalling link across the network. TheMS sends the layer 2 SABM (Set Asynchronous Balanced Mode) to the BTS onthe TCH. The SABM (c) contains a layer 3 service request message. The MSspecifies the service type required to the network through the service requestmessage.

The service request message is as follows:

1. CM (Connection Management) Service Request - for mobile originatingcalls and for a mobile originating SMS (Short Message Service) - contains:

. header

. CM service types

. ciphering key sequence number

. MS classmark 2

. mobile identity.



FACCH Call Set-up

2. Paging Response contains:

. header

. ciphering key sequence number

. MS classmark 2

. mobile identity.

3. CM_Re-establishment

The BTS acknowledges the SABM by sending the UA (e) frame to the MS. TheMS expects this acknowledgement within the time T; otherwise it acts asdescribed in I-ETS 300 022-1 (GSM 04.08).

6.3 ESTABLISH_INDICATION message

The BTS forwards the MS service request to the BSC in theESTABLISH_INDICATION message (d), which includes the following data:

. message discriminator: radio link layer management

. message type: establishment indication

. channel number: TCH + SACCH

. link identifier: main signalling channel TCH

. L3 Information - complete L3 service request as received from the MS.

Having received the ESTABLISH_INDICATION message, the mobilemeasurement (power control and handover) algorithm starts.



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FACCH Call Set-up

7 Mode modify procedure of FACCH CallSet-up

The MODE MODIFY procedure changes the channel mode from signalling tospeech. The ASSIGNMENT_REQUEST message from the MSC starts theprocedure.

Figure 5 shows the MODE MODIFY procedure.

Figure 5. MODE MODIFY procedure

MS BTS BSC MSC

a)DT1(ASSIGNMENT REQUEST)

b)MODE MODIFY

c)MODE MODIFY ACKNOWLEDGE

d)DATA REQUEST(CHANNEL MODE MODIFY)

e)CHANNEL MODE MODIFY

f)CHANNEL MODE MODIFY ACK

g)DATA INDICATION(CHANNEL MODE MODIFY ACK)

h)DT1(ASSIGNMENT COMPLETE)



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7.1 ASSIGNMENT_REQUEST message

The ASSIGNMENT_REQUEST message (a) from the MSC involves thefollowing actions:

The MSC sends an ASSIGNMENT_REQUEST message to the BSC for theassignment of channels on the A interface and the Radio interface. Furthermore, itruns a supervisory timer.

If the MSC fails to receive any response, that is, theASSIGNMENT_COMPLETE or ASSIGNMENT_FAILURE message, from theBSS within the defined time, the MSC is expected to clear the call with aCLEAR_COMMAND message. The BSS releases the MS connection with theCHANNEL RELEASE procedure.

The BSC expects to receive the following fields in theASSIGNMENT_REQUEST message:

. message type

. channel type: speech, TCH/F or TCH/H, speech algorithm

. L3 header information

. priority <OPTION>

. circuit identity code indicating the channel to be used on the A interface

. downlink DTX flag <OPTION>

. radio channel identity <OPTION>

. interference band to be used <OPTION>.

If any of the situations listed below is identified without taking any actiontowards the BTS, the BSC will reject the request with theASSIGNMENT_FAILURE message on analysing theASSIGNMENT_REQUEST message. On receiving theASSIGNMENT_FAILURE message, the MSC can either issue a CLEARCOMMAND or retry.



FACCH Call Set-up

1. If the BSC is not able to use the A channel indicated in theCIC (Circuit Identification Code) because it is used foranother call, the BSC rejects the message with the causerequested terrestrial circuit already allocated .

2. If the BSC is not able to use the A channel indicated in theCIC because the channel has been marked as faulty, the BSCrejects the message with the cause request terrestrial resourceunavailable .

3. If the CIC is blocked, the BSC rejects the request with theASSIGNMENT_FAILURE message (the cause requestedterrestrial resource unavailable ) and sends a BLOCKmessage to the MSC. For reasons which cause a circuit to beblocked by the BSC, see ETS 300 590 (GSM 08.08).

4. If there is no circuit pool on the A interface which is able tosupport the requested type of TCH, the BSC sends anASSIGNMENT_FAILURE message with cause requestedtranscoding/rate adaption not available to the MSC.

5. If there is a circuit pool on the A interface which is able tosupport the requested type of TCH but the pool implied by theCIC is totally contradictory with the TCH type requirement,the BSC sends an ASSIGNMENT_FAILURE message withthe cause circuit pool mismatch to the MSC.

6. If the circuit pool implied by the CIC is at least partiallycompliant with the requested TCH type the change of thecircuit pool may be required. Reasons for the change are theactual traffic channel resource situation of the cell and theattempt to allocate the resources in the most optimized way. Inthis case the BSC can send the ASSIGNMENT_FAILUREmessage with the cause switch circuit pool .

7. If requested speech coder versions are not supported, the BSCsends an ASSIGNMENT_FAILURE message with the causerequested speech version unavailable to the MSC.

8 If the radio interface data rate requirement is totallycontradictory with the requested TCH channel rate, the BSCsends an ASSIGNMENT_FAILURE message with the causeinvalid message contents to the MSC.

If the MSC receives an ASSIGNMENT_FAILURE message with a causeindicating a CIC problem, the MSC may choose to send anotherASSIGNMENT_REQUEST for the same call using a different circuit.



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7.2 MODE_MODIFY in the BSS

If the ASSIGNMENT_REQUEST is valid, the BSC proceeds to perform theMODE_MODIFY procedure.

The BSC first sends the MODE_MODIFY message (b) to the BTS to change thechannel mode from signalling to speech. At this point the BSC connects the Abischannel to the A channel and the speech path is switched through.

Synchronization with the transcoder starts as described in ETS 300 597 (GSM08.60).

The MODE_MODIFY message includes the following data:

. message discriminator: dedicated channel management

. message type: mode modify

. channel number

. channel mode: DTX control and channel type (speech, TCH/F or TCH/H,speech algorithm).

. multirate configuration <option>.

Multirate configuration element is present in calls using multirate speech codec(see Enhanced Speech Codecs ).

On receiving the MODE_MODIFY_ACK message (c), the BSC starts to changethe MS channel mode.

If the BSC fails to receive the MODE_MODIFY_ACK message (c) within thedefined time, or the message does not contain all the information expected, theBSC returns an ASSIGNMENT_FAILURE message to the MSC with the causeequipment failure . The MSC either aborts with a CLEAR_COMMAND messageor retries.

If the BSC receives the MODE_MODIFY_NACK message, the BSC returns anASSIGNMENT_FAILURE_message to the MSC either with the causeequipment failure or requested transcoding or rate adaption unavailable . Thecause value is mapped from the cause value received from theMODE_MODIFY_NACK message. The MSC either aborts with aCLEAR_COMMAND message or retries.



FACCH Call Set-up

7.3 CHANNEL_MODE_MODIFY in the BSS

After receiving the MODE_MODIFY_ACK, the BSC sends theCHANNEL_MODE_MODIFY message (d,e) to the MS and starts a timer. Thiscommand is transparent to the BTS and is transferred as the DATA_REQUESTmessage over the Abis interface.

The CHANNEL_MODE_MODIFY gives the MS all the information necessaryto change the channel mode to speech. The message consists of the following:

. header

. channel description

. channel mode: speech full rate or speech half rate.

. multirate configuration <option>.

Multirate configuration element is present in calls using multirate speech codec(see Enhanced Speech Codecs ).

On receiving the CHANNEL_MODE_MODIFY over the Radio interface, theMS changes the channel mode from signalling to speech and acknowledges it tothe BSC by sending the CHANNEL_MODE_MODIFY_ACK message to it. Thismessage is transparent to the BTS and is transferred over the Abis as aDATA_INDICATION message (g). The BSC checks the channel mode IE of theCHANNEL_MODE_MODIFY_ACK message. If - instead of the one that wasordered - the old mode is returned, the procedure has failed (see ETS 300 597(GSM 08.60)). If the ordered mode is returned, the BSC sends theASSIGNMENT_COMPLETE message (h) to inform the MSC of the successfulchannel MODE MODIFY procedure.

If the timer for waiting for the CHANNEL_MODE_MODIFY_ACK messageexpires, the BSC returns an ASSIGNMENT_FAILURE message to the MSCwith the cause radio interface message failure . The MSC either aborts or retries.



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FACCH Call Set-up

Glossary

AGCH Access Grant Channel

BCCH The Broadcast Control Channel is a unidirectional channel from a network to anMS.

BSC Base Station Controller

BSS Base Station Subsystem

BTS Base Transceiver Station

CCCH The Common Control Channel covers the logical channels of the type RACH,PCH and AGCH.

FACCH The Fast Associated Control Channel is always associated with a traffic channel.

GSM phase There are two possibilities for the GSM phase: GSM phase 1 and GSM phase 2.On the GSM phase 1 level, the network element is compliant with the protocolsdefined by the GSM phase 1 specifications. Respectively, on the GSM phase 2level, the network element is compliant with the protocols defined by the GSMphase 2 specifications.

IMSI International Mobile Subscriber Identity

MMI Man-Machine Interface

MS Mobile Station

MSC Mobile Services Switching Centre

NECI New establishment causes support.

NMS Network Management System

NSS Network Switching Subsystem

Ordinary call Refers to both MS originated and terminated calls.

Phase 1 MS An MS that complies with the protocols defined in Phase 1 GSM specifications.

Phase 2 MS An MS that complies with the protocols defined in Phase 2 GSM specifications.

PLMN Public Land Mobile Network

PSTN Public Switched Telephone Network

RACH Random Access Channel



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Glossary

SACCH The Slow Associated Control Channel is always associated with a traffic channelor an SDCCH.

SDCCH Stand alone Dedicated Control Channel

TCH Traffic Channel

TMSI The Temporary Mobile Subscriber Identity field is included in the cell selectionparameter IE. The information in this field is broadcast in the frames of SystemInformation 3 and 4 to the mobile stations.



FACCH Call Set-up

Documents

FACCH Call Set-up