Call Setup Analysis - A Drive Test Perspective

RADIO PLANNING AND OPTIMISATION

Call Setup Analysis – A Drive Test Perspective (Presentation/Discussion) 27 July 2009

By

Grant Chivandire Grant Chivandire - Radio Planning and Optimisation Specialist

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Objectives This presentation will cover the following:  System Info Messages  Types of MOC  Signaling Flow for MOC  Call Setup Failures & possible causes

Grant Chivandire - Radio Planning and Optimisation Specialist

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System Info Messages  Contain network parameters sent to MS through air interface  These parameters are:  Network Identity parameters  Cell selection parameters  System control parameters  Network function parameters


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System Information Messages – Idle Mode These are sent to the MS on BCCH  SYS INFO 1  Contains RACH control information and cell channel description  These include the following: • Cell frequency allocation (CA list) • Maximum retransmission times (Max retrans) • Extended transmission timeslots (Tx_interger) • Cell Bar access (CBA) • Common access control level (AC) • Call re-establish permitted (RE) • Emergency calls permitted (EC)


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System Information Messages – Idle Mode  SYS INFO 1 Message from ACTIX


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System Information Messages – Idle Mode  SYS INFO 2  Contains the following: • Neighbour cell description • NCC permitted • RACH control parameters (same as in SYS INFO TYPE 1)

 SYS INFO 2 Message from ACTIX


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System Information Messages – Idle Mode  SYS INFO 3  Contains the following: • Location Area Identity (MCC, MNC, LAC, CI) • Control channel description (reserved Access Grant Blocks, CCCH Configuration, IMSI Attach/Detach allowed, Paging Multiframes, T3212) • Cell Option (Power control indication, DTX, RLINKT) • Cell Selection (MS_TXPWR, ACCMIN, ACS, NECI) • RACH control parameters (same as in SYS INFO TYPE 1)


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System Information Messages – Idle Mode  SYS INFO 3 Message from ACTIX


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System Information Messages – Idle Mode  SYS INFO 4  Contains the following: • Cell Selection Parameters • RACH Control Parameters • CBCH Channel description  SYS INFO 4 Message from ACTIX


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System Information Messages – Dedicated Mode These are sent to the MS on SACCH  SYS INFO 5  Contains neighbour cell BCCH frequencies (Phase 1 Mobiles)  SYS INFO 5 Bis  Contains neighbour cell BCCH frequencies which could not fit in the limited space of TYPE 5 and belong to the same band as serving BCCH  SYS INFO 5TER  Contains neighbour cell BCCH frequencies whose band is different from serving BCCH (Dual Band Mobiles)  SYS INFO 5TER Message from ACTIX


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System Information Messages – Dedicated Mode  SYS INFO 6  Contains the following: • Cell Identity • LAI • Cell option • NCC Permitted  SYS INFO 6 Message from ACTIX


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Mobile Originating Call - MOC Types  Early Assignment  The network assigns the TCH+FACCH after sending CC Call Proceeding and completes call setup on the FACCH  Late Assignment  The network does not assign the TCH+FACCH until after alerting has started

 Very Early Assignment  The network makes an immediate assignment to the TCH+FACCH in the initial RR establishment and performs the entire transaction on the FACCH  The SDCCH is not used Grant Chivandire - Radio Planning and Optimisation Specialist

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Signaling Flow of MOC


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Signaling Flow – MOC (Um Interface)  Channel Request (uplink)  MS sends Channel Request message on the RACH  Message contains the following: • Cause value – MOC • Random reference number  Channel Request Message from ACTIX


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Signaling Flow – MOC (Um Interface)

(Cont…)

 Immediate Assignment (downlink)  BSC sends immediate assignment through the BTS to the MS on AGCH  Message contains the following: • Details of the signaling channel being assigned • Request reference details  Immediate Assignment Message from ACTIX


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(Cont…)

 Setup (uplink)  MS sends setup message to the MSC on SDCCH  Message contains the following: • Bearer capabilities • B-number details  Setup Message from ACTIX

 NB: Authentication and Ciphering have been omitted Grant Chivandire - Radio Planning and Optimisation Specialist

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(Cont…)

 Call Proceeding (downlink)  MSC send call proceeding message to MS on SDCCH informing it that the call setup is in progress  Message contains the following: • Transaction ID which maybe co-related to the relevant SETUP message  Call Proceeding Message from ACTIX


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(Cont…)

 Assignment Command (downlink)  BSC sends Assignment Command to MS on SDCCH  Message contains the following: • Details of the traffic channel being assigned • Amount of power to be used by the MS  Assignment Command Message from ACTIX


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(Cont…)

 Assignment Complete (uplink)  MS sends Assignment Complete message to BSC on FACCH after it has switched to the assigned TCH  Assignment Complete Message from ACTIX


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(Cont…)

 Alerting (downlink)  MSC sends Alerting message to MS on FACCH  The MS will hear the ring-back

 Alerting Message from ACTIX


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(Cont…)

 Connect (downlink)  MSC sends Connect message to MS on FACCH  This happens after the called party has answered the call  Calling MS switches over to voice on the assigned TCH  Connect Message from ACTIX


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(Cont…)

 Connect Acknowledgement (uplink)  MS sends a Connect Acknowledgement to MSC on FACCH  Call has been successfully setup

 Connect Acknowledgement Message from ACTIX


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Call Setup Failure  RACH Success


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Call Setup Failure  Paging Success


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Call Setup Failure  High SDCCH Congestion Rate


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Call Setup Failure  High SDCCH Drop Rate


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Call Setup Failure  High TCH Congestion Rate


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Call Setup Failure  Disconnect Cause  Disconnect cause code • Layer 3 message contains the cause code and description for the disconnection • Get more information from 3GPP TS 24.008 document


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THANK YOU !

Call Setup Analysis - A Drive Test Perspective

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