Idle Mode

Content

Cell Selection

Cell Reselection

Parameter Configuration

Cell Selection

The UE will select an initial cell at power-on or do registration after ‘out of service’ conditions.

When the UE moves in the IDLE mode, in state URA_PCH or CELL_FACH, it needs to change the cell that it camps on through the cell reselection strategy.

Cell Selection for FDD cells: Srxlev > 0 AND Squal > 0

for TDD cells: Srxlev > 0

Squal = Qqualmeas – Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Qqualmeas: The quality of received signal expressed in CPICH Ec/N0 (dB). Qrxlevmeas: Measured cell RX level value. This is received signal, CPICH RSCP for FDD

cells (dBm), P-CCPCH RSCP for TDD cells (dBm) and RXLEV for GSM cells (dBm). Qqualmin: Minimum required quality level in the cell (dB). Qrxlevmin: Minimum required RX level in the cell (dBm).

Pcompensation ＝ max(UE_TXPWR_MAX_RACH – P_MAX, 0)

UE_TXPWR_MAX_RACH: Maximum TX power level MaxRACHTxPwr on RACH (read in system information) (dBm) (for cells under the RNC, it is the max value of MaxRACHTxPwr (Prach); for cells under other RNC, it is the value of MaxRACHTxPwr (externalUtranCell)).

P_MAX: Maximum RF output power of the UE (dBm)

Content

Cell Selection

Cell Reselection

Parameter Configuration

Cell Reselection

If the serving cell uses the HCS (UseOfHCS (utranCell)) structure, the following cell reselection rule H is used for quality ranking in cell reselection.

Hs = Qmeas,s - Qhcss

Hn = Qmeas,n - Qhcsn – TOn * Ln

TOn = TEMP_OFFSETn * W(PENALTY_TIMEn – Tn)

Ln = 0 if HCS_PRIOn = HCS_PRIOs

Ln = 1 if HCS_PRIOn <> HCS_PRIOs

W(x) = 0 for x < 0W(x) = 1 for x >= 0

Cell Reselection

If the cell does not use the HCS structure, the following cell reselection rule R is used for quality ranking in cell reselection.

Rs = Qmeas,s + Qhysts + Qoffmbms Rn = Qmeas,n - Qoffsets,n + Qoffmbms - TOn * (1 – Ln)

TOn = TEMP_OFFSETn * W(PENALTY_TIMEn – Tn)

Ln = 0 if HCS_PRIOn = HCS_PRIOs

Ln = 1 if HCS_PRIOn <> HCS_PRIOs

W(x) = 0 for x < 0W(x) = 1 for x >= 0

How the suitable cell is selected

If a TDD or GSM cell is ranked as the best cell, then the UE will perform cell re-selection to that TDD or GSM cell and camps on the chosen cell.

If an FDD cell is ranked as the best cell and the quality measurement for cell selection and re-selection is set to CPICH RSCP, the UE will perform cell re-selection to that FDD cell and and camps on the chosen cell

If an FDD cell is ranked as the best cell and the quality measure for cell selection and re-selection is set to CPICH Ec/No, the UE shall perform a second ranking of the FDD cells according to the R criteria specified above, but using the quality measure CPICH Ec/No for deriving the Qmeas,n and Qmeas,s and calculating the R values of the FDD cells

Content

Cell Selection

Cell Reselection

Parameter Configuration

Parameter Configuration

Parameter Configuration

Parameter Configuration

13

Intra-Frequency Cell Reselection

Time

P-CPICH Ec/No

Serving CellServing Cell

Neighboring Cell

Neighboring Cell

Neighboring cell criterion S

is fulfilled and is ranked

Neighboring cell better ranking

than Serving cell

UE perform cell reselection

Treselections

Qhyst2s

Qoffset2s,n

Qqualmin

UE perform intra-frequency measurements

Qqualmin + SIntraSearch

Intra-Frequency Cell Reselection Key Parameter ListParameter Explanation

QqualminThe parameter indicates the cell’s minimum required quality value which fulfills the cell selection suitability criterion. The measured cell whose CPICH Ec/No is lower than Qqualmin cannot be selected.

Qrxlevmin

The parameter indicates the cell’s minimum required Rx level value which fulfills the cell selection suitability criterion. The measured cell whose CPICH RSCP or Rx level is lower than Qrxlevmin cannot be selected.

SintrasearchThe parameter indicates the threshold to trigger the measurement for intra-frequency cell reselection.

Qhyst2sThe parameter indicates the hysteresis value for FDD cells when the measurement quantity for cell reselection is CPICH Ec/No.

Qoffset2s,nThe parameter indicates the offset between the serving cell and

neighbor cell when measurement quantity is CPICH Ec/No.

Treselection This parameter indicates the cell reselection timer value.

Inter-RAT Cell Reselection Sample

Time

Quality/RxLev

GSM Serving Cell

WCDMA Serving Cell

GSM Neighboring Cell WCDMA

Neighboring Cell

Inter-RAT cell criterion S is fulfilled and is

ranked

Neighbor cell is better ranking

than Serving cell

UE performs inter-RAT cell

reselection

Treselections

Qhyst1s

Qoffset1s,n

Qrxlevmin(GSM)

UE performs inter-RAT

measurements

Qqualmin + SSearchRat

3G→2G Cell Reselection Key Parameter List

Parameter Explanation

QqualminThe parameter indicates the cell’s minimum required quality value which fulfills the cell selection suitability criterion. The measured cell whose CPICH Ec/No is lower than Qqualmin cannot be selected.

QrxlevminThe parameter indicates the cell’s minimum required Rx level value which fulfills the cell selection suitability criterion. The measured cell whose CPICH RSCP or Rx level is lower than Qrxlevmin cannot be selected.

SSearchRatThe parameter indicates the threshold to trigger the measurement for inter-RAT cell reselection.

Qhyst1sThe parameter indicates the hysteresis value for FDD cells when the measurement quantity for cell reselection is CPICH RSCP.

Qoffset1s,nThe parameter indicates the offset between the serving cell and neighbor cell when measurement quantity is CPICH RSCP.

Treselection This parameter indicates the cell reselection timer value.