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Idle Mode and Common Channel Behavior

Idle Mode and Common Channel Behavior. PLMN Selection Cell Selection / Reselection LA / RA Update Paging System Information. Functions. Automatic PLMN Selection. Last registered PLMN Home PLMN PLMN priority List from “user controlled” USIM

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Idle Mode and Common Channel Behavior

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  1. Idle Mode and Common Channel Behavior

  2. PLMN Selection Cell Selection / Reselection LA / RA Update Paging System Information Functions

  3. Automatic PLMN Selection • Last registered PLMN • Home PLMN • PLMN priority List from “user controlled” USIM • PLMN priority List from “operator controlled” USIM • Other PLMN where RSCP > -95 dBm in random order • Other PLMN where RSCP <= -95 dBm in descending order If Not Available If Not Available If Not Available If Not Available If Not Available *In case HPLMN was not available for selection, it will be tried again in 30min. during national roaming (default)

  4. P-CCPCH (PSC + SSC + BCH) UE monitors Primary SCH code, detects peak in matched filter output Slot Synchronization Determined ------> UE monitors Secondary SCH code, detects SCG and frame start time offset Frame Synchronization and Code Group Determined ------> UE determines Scrambling Code by correlating all possible codes in group Scrambling Code Determined ------> UE monitors and decodes BCH data BCH data, Super-frame synchronization determined ------> UE adjusts transmit timing to match timing of BS + 1.5 Chips Cell Synchronization complete Cell Search Initiate Cell Synchronization

  5. Cell Selection These 2 parameters allow the carrier to reserve or limit access to the cells in the network; CellReserved Reserved ; Not Reserved (If Reserved, there will be no service to UEs) AccessClassNBarred [0-65535] (Each bit corresponds to an Access Class)

  6. Cell selection criteria: IF Squal > 0 AND Srxlev > 0 then cell selection criteria are met CPICH Ec/No [dB] measured by UE Sent on SIB3 CPICH RSCP [dBm] measured by UE max(maxTxPowerUl - P, 0) Cell Selection Squal = Qqualmeas – qQualMin Srxlev = Qrxlevmeas – qRxLevMin - Pcompesation

  7. Cell Reselection happens; When the UE is camped normally has found a better neighbouring cell than the cell on which it is camping When the cell on which it is camping is no longer suitable The cells to camp on are ranked based on R criteria; R (serving) = Qmeas(s) + qHyst(s) R (neighbour) = Qmeas(n) - qOffset(s,n) Cell Reselection qHyst1 CPICH RSCP qOffset1sn CPICH RSCP qHyst2 CPICH Ec/No qOffset2sn CPICH Ec/No QMeas can be either RSCP or Ec/No depending on the value of parameter QualMeasQuantity. For GSM cells it always is RSCP. For WCDMA it is Ec/No by default

  8. Camp on Neigbour1 ranking ranking ranking Measurement Quantity QHyst1 1 Serving cell 1 2 2 Neighbour 1 1 2 Qoffset1sn Neighbour 2 3 3 3 treSelection Cell Reselection WCDMA Same idea as in GSM, serving cells are favored while neighbors are penalized

  9. UE starts Intra-frequency measurements if : Squal<=sIntraSearch [2 dB] Measurements in Idle Mode • UE starts Inter-Frequency measurements if : Squal<=sInterSearch [2 dB] • UE starts GSM measurements if : Squal<=sRATSearch [2 dB] And/or Srxlev<=sHcsRat [2 dB]

  10. Cell Reselection IRAT treSelection (2 sec.)

  11. IeF & IRAT Measurements in Cell_FACH mode Measurements are controlled by 2 parameters in Cell_FACH mode; interFreqFddMeasIndicator: TRUE or FALSE depending on presence of IeF neighbors TRUE  UE will perform measurements and evaluate cell reselection criteria on IeF cells FALSE  UE will not perform measurements and will not evaluate cell reselection criteria on IeF cells fachMeasOccaCycLenCoeff= 4  with this setting the UE will leave the FACH channel every 16th frame to perform measurements on IeF or IRAT neighbors (2fachMeasOccaCycLenCoeff = 24 = 16 (IeF or IRAT) or 23=8 (IeF and IRAT) )

  12. Mobility Management Registrations • Location / Routing Area Update • A new cell w/ different LAC/RAC • Periodic Registration • LU is controlled by T3212 sent on BCCH • RU is controlled by T3312 (CN parameter) • IMSI attach/detach • During Switch on & off

  13. tPICH PICH • • • Frame withPI Indicator • • • AssociatedS-CCPCH frame • • • S-CCPCH • • • Paging • UEs can be paged on; • Idle Mode (Type I)  via PICH & PCH [S-CCPCH] • Cell_FACH Mode (Type II)  via DCH • Cell_DCH Mode (Type II)  via DCH Idle Mode Paging PCH is only decoded when PICH indicates that there is a paging for UEs paging group DRX (Discontinuous Reception) is used to limit battery consumption in idle mode

  14. Master Information Block System Information Block 1 System Information Block 3 System Information Block n Master / System Information Blocks The UE reads the system information on the BCCH when the following events occur: • UE is powered up • UE changes cell in Idle mode or in state CELL_FACH • UE is informed of a change of System Information, when the UE is in Idle mode or state CELL_FACH • UE moves from dedicated mode to common mode • Timer expires for SIBs • The SIBs contain all information necessary for UEs to work properly in both Idle and Connected mode • Each SIB contains different kinds of information • Each SIB has its own repetition period (sibxRepPeriod) • The MIB has a fixed, predefined repetition rate equal to 80 ms

  15. Mapping of System Information onto MIB and SIBs

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