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Cell Selection and Reselection
3GRPLS (RN3155) – Section 4
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CM requestsNAS controlradio
measurements
PLMNselected
PLMNavailable
registrationarea changes
locationregistration
response
indicationto user
manual mode
locationregistration
cell selectionand reselection
PLMN selectionand reselection
automatic mode
RRC tasks:
• PLMN selection & reselection;
• Cell selection & reselection;
• Location registration LR.
if the UE is in the RRC idle mode
if the UE is in the RRC connected modestates:• CELL_FACH,• CELL_PCH &• URA_PCH
Cell Selection and Reselection: Motivation
TS 25.304:Idle mode task
subdivided into 3 processes:
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PLMN search
Search PLMNs
UTRA:
If RSCP > -95 dBm
GSM:
If RSSI > -85 dBm
High qualityPLMNs
Other foundPLMNs
PLMN IdPLMN Id+ RSCP/RSSI
UE AS
UE NAS
TS 25.304 & TS 43.022
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Operator controlled PLMN list
User controlled PLMN list
Last registered PLMN
Home PLMN
Other high quality PLMN‘s in random
order
Switch onin automatic PLMN selection operation mode
HPLMN Search Period Timer6 .. 480 minutesDefault: 60 minutes
PLMN Selection
Other PLMN‘s in decreasing signal
quality order
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Cell- acceptable (limited services*)- suitable (full service set)- barred- reserved#
Access Class barred:(UE access classes 0..9 and 11..15)
BCCH SIB3/4: Cell Access Restriction
Cell status and special reservations
* e.g. Emergency Call (Access Class = 10) in Network w/o Roaming Agreement# e.g. for operator use
Cell status &special reservations: Access Control
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Cell Barred Cell reservedfor operator
Cell reservedfor future extension
Case
1
2
3
4
not barred
not barred
not barred
barred
not reserved not reserved
not reserved reserved
reserved ---
--- ---
suitable for selection and reselection
suitable for AC 11 or 15 in HPLMN otherwise “barred”
Cell “barred”
Not suitable – not even for emergency call
Cell status and special reservations
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UE RRC idle
I ignore all Access Class related cell
access restrictions when selecting a cell
to camp on
UE RRC connected
Access Class only relevant for access
(from RRC IDLE)
Access Class irrelevantfor access
suitable cell
suitable cell
Access Control
Access Control normallyused for load reasons:
Overload Control feature
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• WCEL: CellBarred•Defines whether the cell is barred or not. •A barred cell is a cell where a UE is not allowed to camp on. •This parameter is part of SIB 3.•0 (Barred), 1 (Not barred); default: 1.
• WCEL: TBarred•If the UE does not select another cell, and the barred cell remains to be the “best” one, the UE shall after expiry of the time interval Tbarred again check whether the status of the barred cell has changed.•This parameter is part of SIB 3.•[10, 20, 40, 80, 160, 320, 640, and 1280] seconds; default: 40 seconds.
• WCEL: Cell_Reserved•Defines whether the cell is reserved for operator use. •This parameter is part of SIB 3.•0 (Reserved), 1 (Not reserved); default: 1.
• WCEL: IntraFreq_Cell_Reselect_Ind•Defines whether intra-frequency cell re-selection is allowed when the cell is barred.•This parameter is part of SIB 3/4.•0 (Allowed), 1 (Not allowed); default: 0.
NSN Parameters for Cell Reservations and Restrictions
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Cell Selection Process
NAS controls
AS controlscorrespondentprocedures
NAS:
PLMNselection
• RAT(s) information associated with the selected PLMN• forbidden registration areas• list of equivalent PLMNs
UE CN
AS:attempts to find suitable cells
States and State Transition in the RRC Idle Mode
suitablecell
found
campednormally
campedon any cell
all networkservices available
limited servicese.g. Emergency Call
YES
NO
acceptable cell
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1
Initial Cell Selection
Camped normally
Cell Reselection Evaluation
Process
no cell information stored for the PLMN
cell information stored for the PLMN
go here whenever a new PLMN is selected
no suitable cell found
suitable cell found suitable cell found
Connected Mode
suitable cell found
no suitable cell found
no suitable
cell found
Stored Information
Cell Selection
trigger
suitable cell selected
no suitable cell found
Cell Selection when leaving
connected mode
leave idle mode
return to idle mode
NAS registration
rejected
(adopted from TS 25.304)
States and State Transition in the RRC Idle Mode
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Camped on Any Cell
Any Cell Selection
Connected Mode
(Emergency calls only)
return to idle mode
go here when no USIM in the UE
USIM inserted 1
leave idle mode
no acceptable cell found
an acceptable cell found
Cell Selection when leaving
connected mode
acceptable cell found
suitable cell found 1
Cell Reselection Evaluation
Process
trigger
acceptable cell selected
no acceptable cell found
(adopted from TS 25.304)
States and State Transition in the RRC Idle Mode
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Qqualmeas (dB)(CPICH Ec/N0)
Qrxlevmeas (dBm)CPICH RSCP
Qrxlevmin
Srxlev > 0
Pcompensation
Squal > 0S-Criterion
fulfilledSqual >0 AND
Srxlev > 0
suitable
cell?
Cell Selection Criterion S (in the FDD mode)
Squal =CPICH Ec/No – QqualMin
Srxlev =Qrxlevmeas – Qrxlevmin– Pcompensation
QqualMin:-24...0; def.: -18 dB
SIB 11/12
AdjsQrxlevmin:-115...-25; def.:-115 dB
SIB 11/12
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Cell Selection Criterion S
Pcompensation= max(UE_TXPWR_MAX_RACH – P_MAX, 0)
Cell size defining parameters:• Qrxlevmin• Qqualmin
I am outsid
e
I am inside, but have not
enough power
-50 .. 33 dBm
UEtxPowerMaxPRACH-50..33 dBm; 21 dBm
SIB3/4
AdjsQrxlevmin:-115...-25; def.: -115 dB
Srxlev = Qrxlevmeas – Qrxlevmin– Pcompensation
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Initial Cell Selection(scan RF channel)
Stored Information Cell Selection
carrier, even Scr.Code may be stored in UE
or
I have to find a suitable
cell
Squal = Qqualmeas – Qqualmin > 0Srxlev = Qrxlevmeas – Qrxlevmin – Pcompensation > 0
Once a suitable cell is found this cell is selected
(Initial) Cell Selection Process
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• Active Set cells as candidates for cell selections; if not suitable, then
• Stored information cell selection Squal > 0Srxlev > 0
Cell Selection When Leaving the RRC Connected Mode
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• WCEL: QrxlevMin •The minimum required RX level in the cell. •This parameter is part of SIB 3.•[-119 ... –25] dBm, step 2 dBm; default: -115 dBm.
• WCEL: QqualMin•The minimum required quality level in the cell (Ec/No). •This parameter is part of SIB 3.•[-24 ... 0] dB, step 1 dB, default: -18 dB.
• WCEL: UEtxPowerMaxPRACH•This parameter defines the maximum transmission power level a UE can use on PRACH. •The value of the parameter also effects the cell selection and reselection procedures. •The value of the parameter is sent to UE in the Cell selection and re-selection of SIB 3 and 4 of the serving cell.[..]
NSN Parameters for Cell Selection
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S-Criterionfulfilled
cells with highest HCSPriorities &H > 0
measurementthresholds
cells with lower HCS
priority than in serving cell
If No Cellwith H>0accept allneighbours
HCS in use: HCS not in use:
S-Criterionfulfilled
measurementthresholds
H-Criterionfor fast
moving UEsfor slow
moving UEs
R-Criterioncell ranking
R-Criterioncell ranking
R-Criterioncell ranking
Cell Reselection in the RRC Idle and RRC Connected Mode
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Hierarchical Cell Structures
3
3
3
33
3
1
2
2
2
Normally, different layers are created using different frequencies
Priority
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Cell reselection without HCS
• Normal re-selection process (without HCS) follows simplified procedure
• Measurement criteria without HCS
• S-criteria
• R-criteria
Without HCS
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Cell reselection without HCS
Measuredneighbours
Neighbour listfrom BCCH
Best ranked cell
Measurement criteria
S – criteriaSuitable
neighbours
R – criteria
Re-selection if not serving cell
Without HCS
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SintrasearchSintersearchSsearchRAT m
No need to measure
neighbour cells
Intra- frequency
Sx=Squal (in FDD mode)
Intra-frequencyInter-frequency
serving cell
Example: NSN Qqualmin = -18 dB, Sintrasearch = 10dB, Sintersearch = 8dB,Ssearch_RAT = 4dB
When to perform measurements
Intra-frequency
Inter-freqencyInter-RAT
Cell Reselection: Measurement RulesWithout HCS
-8 dB-10 dB-14 dBEC/N0 =
SinterSearch:0...20; def.: 8 dB
SintraSearch:0...20; def.: 10 dB
Ssearch_RAT:0...20; def.: 4 dB
QqualMin:-24...0; def.: -18 dB
Squal =CPICH Ec/No
-qQualMin
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Rs = Qmeas,s + Qhysts
Rn = Qmeas,n - Qoffsets,n
Qmeas,n
Qmeas,s
Qm
eas
Rs
Rn
Qoffsets,n
Qhysts
Rn > Rs =>“cell reselection“
Treselection
Cell Reselection: R-CriterionWithout HCS
Qmeas = Ec/No or RSCPEc/No Qhyst2 /RSCP Qhyst1Rs / Rn: Serving / Neighbouring cell value
Qhyst20.. 40; def.: 2 dB
AdjisQoffset2-50.. 50; def.: 0 dB
FDD cells & Ec/No:2nd Ranking
Adjg,s,iQoffset1-50.. 50; def.: 0 dBQhyst1
0.. 40; def.: 0 dB
WCDMA & GSM cells; RxLev:
1st Ranking
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• WCEL: UseOfHCS•This parameter indicates whether the serving cell belongs to a Hierarchical Cell Structure (HCS). •This parameter is part of SIB 11/12.•0 (HCS not used), 1 (HCS in use); default: 0.
• WCEL: Sintrasearch•The threshold for intra-frequency measurements, and for the HCS measurement rules.•This parameter is part of SIB 3.•[0 ... 20] dB, step 2 dB, default: 10 dB.
• WCEL: Sintersearch•The threshold for inter-frequency measurements, and for the HCS measurement rules.•This parameter is part of SIB 3.•[0 ... 20] dB, step 2 dB, default: 8 dB.
• WCEL: Ssearch_RAT•The RAT-specific threshold for inter-RAT measurement rules. •This parameter is part of SIB 3.•[0 ... 20] dB, step 2 dB, default: 4 dB.
NSN Parameters for Cell Reselection (Part I)
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Cell reselection with HCS
• Normal re-selection process (without HCS) follows procedure
• Measurement criteria without HCS
• S-criteria
• H-criteria
• R-criteria
• HCS specific H-criteria defines whether priorities are applied in re-selection
With HCS
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Cell reselection with HCS
Measuredneighbours
Neighbour listfrom BCCH
Best ranked cell
Measurement criteriawith HCS
S – criteria
Neighboursto rank
R – criteria
Re-selection if not serving cell
With HCS
Suitableneighbours
H – criteria
Prioritizedneighbours
UseOfHCS0 (not used), 1 (used)
SIB 11/12
HCS_PRIO0 (lowest) ..
7(highest); step: 1SIB 11/12
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Higher HCS priority
Intra-frequencyInter-frequency
Intra-frequencyInter-frequency
Equal &higher HCS
priorityIntra-
frequencyInter-
frequency
Example: NSN Sintrasearch = 10 dB, Sintersearch = 8 dB,Ssearch_RAT = 4 dB,SsearchHCS = -1 dB
Cell Reselection: Measurement RulesWith HCS
SintrasearchSintersearchSsearchRAT mSlimitsearchRAT m
Sx=Squal (in FDD mode)if Srxlevs > SsearchHCS
BCCH SI: HCS is used
-8 dB-10 dB-14 dBEC/N0 =
Srxlevs ≤ SsearchHCSif SsearchHCS
-1..91; def.: -1 dB*SIB3
AdjsQrxlevmin:-115...-25; def.: -115 dB
SIB 11/12
Srxlev =Qrxlevmeas – Qrxlevmin
-115 dBmRSCP =
*negative values are set to 0 by UE
Srxlevs ≤ SsearchHCS OR Squal ≤ Sintersearch
Squal =CPICH Ec/No
- QqualMin
QqualMin:-24...0; def.: -18 dB
SIB 11/12
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Example: NSN Sintrasearch = 10 dB, Sintersearch = 8 dB,Ssearch_RAT = 4 dB, Slimit, searchRAT = 2 dB SsearchHCS = -1dB, SHCS_RAT = -1dB
Cell Reselection: Measurement RulesWith HCS
or
SintrasearchSintersearchSsearchRAT m
Higher HCS priority
Intra-frequencyInter-frequency
SlimitsearchRAT m
Intra-frequencyInter-frequency
Intra-frequency
Inter-freqencyInter-RAT
Intra-frequency,
Inter-frequency, &
Equal and higher HCS priority inter
RAT
Equal &higher HCS
priorityIntra-
frequencyInter-
frequency
Sx=Squal (in FDD mode)
if Srxlevs ≤ SHCS,RATm measure on allInter-RAT cells
if Srxlevs > SHCS,RATm
HCS; Inter-RAT measurements?
-14 dBEC/N0 =
Slimit,SearchRAT0..20; def.: 2 dB
SIB3
-16 dB
SHCS_RAT-1..91; def.:-1 dB*
SIB3
AdjsQrxlevmin:-115...-25; def:. -115 dB
SIB 11/12
Srxlev =Qrxlevmeas – Qrxlevmin
-115 dBmRSCP ≤
*negative values are set to 0 by UE
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• WCEL: SHCS_RAT•The RAT specific threshold for inter-RAT measurement rules. •This parameter is part of SIB 3.•[-1 ... 91] dB, step 2 dB, default: -1 dB (UE sets this value to 0).
• WCEL: Slimit_SearchRAT•Threshold for skipping inter-RAT measurement rules in HCS. •Above this RAT specific threshold in the serving UTRA cell, the UE does not need to perform any inter-RATm measurements. •This parameter is part of SIB 3.•[0 ... 20] dB, step 2 dB, default: 2 dB.
• WCEL: SsearchHCS•Threshold for intra- and inter-frequency measurement rules in HCS. •Below this limit in the serving cell, the UE initiates measurements of all intra and inter-frequency neighbouring cells of the serving cell. •This parameter is part of SIB 3.•[-1 ... 91] dB, step 2 dB, default: -1 dB (UE sets this value to 0).
NSN Parameters for Cell Reselection (Part II)
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Measurement Rules with HCS and fast moving UEsWith HCS
NCR = cell reselections threshold (default: 8)TCRmax = time period
NCR/TCRmax
fast moving UE
time
TCrmaxHyst
measurement rule for fast moving UEs
measures neighbouring cells with equal or lower HCS priority
priorizes cells with lower HCS priority for re-selection
Example: NSN NCr: 1..16; def.: 8; SIB3TCrmax: not used, 30, 60, 120, 180, 240 s; def.: 60s; SIB3TCrmaxhyst: not used; 10..70; 10; SIB3
measurement rules forslow moving UEs
measurement rules forslow moving UEs
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• WCEL: NCr•This parameter defines the maximum number of cell reselections.•If the number of cell reselections during the TCrmax time period exceeds the value of NCr, high mobility has been detected. •Not used if TCrmax equals 'not used’.•This parameter is part of SIB 3.•[1 ... 16], default: 8.
• WCEL: TCrmax•The duration for evaluating the allowed amount of cell reselections. •If the number of cell reselections during the time period defined by Tcrmax exceeds Ncr, high mobility has been detected. •This parameter is part of SIB 3.•[0 (= not used), 30, 60, 120, 180, 240] seconds, default: 60 seconds.
• WCEL: TCrmaxHyst•Cell reselection hysteresis for reverting from UE high-mobility measurements.•The additional time period before UE reverts to low-mobility measurements.•This parameter is part of SIB 3.•[0 (= not used), 10, 20, 30, 40, 50, 60, 70] seconds, default: 0 seconds.
NSN Parameters for Cell Reselection (Part III)
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Cell Reselection: H-Criterion (slow moving UE)With HCS
HCS is in use:Candidates
for cell re-selection? H-Criterion !
S-Criterionfulfilled
only cells with
highest HCSpriorities &
H > 0
measurementthresholds
cells with lower HCS
priority than in serving cell
H-Criterionfor fast
moving UEsfor slow
moving UEs
R-Criterioncell ranking R-Criterion
cell ranking
Hs = Qmeas,s – Qhcss
Hn = Qmeas,n - Qhcsn – TOn * Ln
accept allNeighbours*
cells withH>0
R-Criterioncell ranking
no cells withH>0
Qhcs#: -24..0; def.: -24 dB
* id. to HCS not in use
TOn: temporary Offset during Penalty Time;3, 6, 9, 12, 15, 18, 21, 100 dB; Infinity; def: 3
#AdjgHCSthreshold:-110..-37; def.: -110 dB
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Cell Reselection: H-Criterion (slow moving UE) and TOn
Qmeas,n - Qhcsn
0time
TOnTOn
PENALTY_TIMEn PENALTY_TIMEn
TOn = 0 TOn = 0
StartTn
StartTn
StopTn
Hs = Qmeas,s – Qhcss
Hn = Qmeas,n - Qhcsn – TOn * Ln
Example:HCS_PRIOn <> HCS_PRIOs
=> Ln = 1
TOn = TEMP_OFFSETn * W(PENALTY_TIMEn – Tn)
temp. offset used only when neighbour has different priority thanserving cell
TOn: temporary Offset during Penalty Time;Adji/g/sTempOffset1
3, 6, 9, 12, 15, 18, 21, 100 dB; Infinity
Ln = 0, if HCS_Prion = HCS_Prios
= 1, if HCS_Prion ≠ HCS_Prios
Penalty_Timen : 0..60; def.: 0s
H-Criterion:H>0
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• WCEL: HCS_PRIO•This parameter defines the HCS priority level for a cell. •Value 0 indicates the lowest HCS priority and value 7 indicates the highest HCS priority.•[0 ... 7], default: 0.
• WCEL: QHCS•Quality threshold level for applying prioritised hierarchical cell re-selection for a cell. •Part of HCS Serving cell information (Qhcss). •This parameter is part of SIB 3. •[-24 ... 0] dB, step 0.5 dB, default: -24 dB.
• HOPS: AdjsHCSthreshold•Defines the threshold level which must be exceeded by the CPICH Ec/No of the intra-frequency neighbouring cell before the hierarchical cell re-selection becomes possible (Qhcsn).•[-24 ... 0] dB, step 0.5 dB, default: -24 dB.
• HOPI: AdjiHCSthreshold: •[-24 ... 0] dB, step 0.5 dB, default: -24 dB.
• HOPG: AdjgHCSthreshold: •[-110 ... -37] dBm, step 1 dBm, default: -110 dBm.
NSN Parameters for Cell Reselection (Part IV)
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• HOPS: AdjsTempOffset1•This parameter is used in the cell ranking between cells when the intra-frequency neighbour cell has the same HCS priority level as the serving cell. •[3, 6, 9, 12, 15, 18, 21, 100 (Infinity)] dB, default: 3 dB. •HOPI: AdjiTempOffset1, •HOPG: AdjgTempOffset1
• HOPS: AdjsTempOffset2•This parameter is used in the cell ranking between WCDMA cells when the intra-frequency neighbour cell has the same HCS priority level as the serving cell. •[2, 3, 4, 6, 8, 10, 12, 100 (Infinity)] dB, default: 2 dB. •HOPI: AdjiTempOffset2
• HOPS: AdjsPenaltyTime•Defines the time period during which the Temporary Offset 1/2 is applied in the cell re-selection procedure for the intra-frequency neighbour cell in question.•[0 ... 60] seconds, step 10 seconds, default: 0.•HOPI: AdjiPenaltyTime, •HOPG: AdjgPenaltyTime
NSN Parameters for Cell Reselection (Part IV)
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Qmeas,n – Qoffsets,n
PENALTY_TIMEn PENALTY_TIMEn
TOn = 0 TOn=0
StartTn
StartTn
StopTn
Rs = Qmeas,s + Qhysts
Rn = Qmeas,n - Qoffsets,n - TOn * (1 – Ls)
Example:HCS_PRIOn = HCS_PRIOs
=> Ln = 0 TOn = TEMP_OFFSETn * W(PENALTY_TIMEn – Tn)
Qmeas,s
temp. offset used only when neighbour has same priority thanserving cell
TOn
TOn
Cell Reselection: R-Criterion and TOnWith HCS
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Cell Reselection: R-CriterionWith HCS
Rs = Qmeas,s + Qhysts
Rn = Qmeas,n - Qoffsets,n - TOn * (1 – Ls)
Qmeas,n
Qmeas,s
Qm
eas
Rs
Rn
Qoffsets,n
Qhysts
Example: HCS_PRIOn <> HCS_PRIOs => Ln = 1
Treselection: 0..31; default: 2s
Adjg,s,iQoffset-50.. 50; def.: 0 dB
Qhyst10.. 40; def.: 0 dB
Qhyst20.. 40; def.: 2 dBAdji&sQoffset2
-50.. 50; def.: 0 dBFDD cells & Ec/No:
2nd Ranking
WCDMA &GSM; RxLev:1st Ranking
Rn > Rs => “cell reselection“
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• WCEL: Qhyst1 (Qhyst2) • Qhyst1 is used for TDD and GSM cells, and for FDD cells when cell selection and re-
selection quality measure is set to CPICH RSCP (CPICH Ec/No) (Qhyst1s/ Qhyst2s). • This parameter is part of SIB 3.• [0 ... 40] dB, step 2 dB, default: Qhyst1 = 0 dB, Qhyst2 = 2 dB.
• HOPS: AdjsQoffset1 (AdjsQoffset2) • This parameter is used in the cell re-selection and ranking between WCDMA cells. • The value of this parameter is subtracted from the measured CPICH RSCP (CPICH Ec/No)
of the intra-frequency neighbour cell before the UE compares the quality measure with the cell re-selection/ranking criteria.
• [-50 ... 50] dB, default: 0 dB. • HOPS: AdjsQoffset1 (AdjsQoffset2), HOPG: AdjgQoffset1
• WCELL: Treselection• The UE triggers the reselection of a new cell if the cell reselection criteria are fulfilled during
the time interval Treselection.• This parameter is part of SIB 3.• [0 ... 31] seconds, default: 2 seconds.
• The remaining parameters were already specified under NSN Parameters for Cell Reselection (Part IV).
NSN Parameters for Cell Reselection (Part V)
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DRXcycle
Nserv
S
S
S S
start measurement on all neighbouring cells
12 seconds
if still no suitable cells
UE initiates cell selection procedures for the
selected PLMN
UE “out of service area”At least one• CPICH Ec/Io
measurement• CPICH RSCP
measurement• S criterion evaluation
DRX cycle
if UE RRC idle
if UE in CELL_FACH, CELL_PCH or URA_PCH
Cell Reselection: Measurement Requirements – Serving Cell
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At least one• CPICH Ec/Io measurement, or
CPICH RSCP measurement
TmeasureFDD cycle
3 dB
Serving cellIntra-frequency cell
time
UE is capable of evaluating that an intra-frequencycell has become better ranked (if Treselection = 0)
within TevaluateFDD
Cell Reselection: Measurement – Intra-frequency Cells
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At least one• CPICH Ec/Io measurement or
CPICH RSCP measurement
(Ncarrier-1) * TmeasureFDD cycle
3 dB for CPICH Ec/Io 5 dB for CPICH RSCP
Serving cellInter-frequency cell
time
UE is capable of evaluating that an inter-frequencycell has become better ranked (if Treselection = 0)
within (Ncarrier -1) * TmeasureFDD
Cell Reselection: Measurement– Inter-frequency Cells
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DRX cyclelength [s]
Nserv [number ofDRX cycles]
TmeasureFDD [s](number of
DRX cycles)
TevaluateFDD [s](number of
DRX cycles)
TmeasureGSM [s](number of
DRX cycles)0.08 4 0.64 (8 DRX cycles) 2.56 (32 DRX cycl) 2.56 (32 DRX cycl)
0.16 4 0.64 (4) 2.56 (16) 2.56 (16)
0.32 4 1.28 (4) 5.12 (16) 5.12 (16)
0.64 4 1.28 (2) 5.12 (8) 5.12 (8)
1.28 2 1.28 (1) 6.4 (5) 6.4 (5)
2.56 2 2.56 (1) 7.68 (3) 7.68 (3)
5.12 1 5.12 (1) 10.24 (2) 10.24 (2)
In idle mode, UE supports DRX cycles lengths 0.64, 1.28, 2.56 and 5.12 s
Each GSM neighbour• GSM BCCH carrier RSSI
TmeasureGSM
BSIC at least every 30 seconds for each of the 4 strongest GSM BCCH carriers
30 seconds
+
(DRX cycle length table source: TS 25.133 V3.11.0 chap. 4.2.2.1)
Cell Reselection: Measurement Requirements + GSM Cells
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50 ms
50 ms
50 ms
TSI
TBCCH
intra-frequency
inter-frequency
inter-RAT
Cell Reselection: Maximum Interruption in Paging Reception