05 mn1889eu11mn 0001 cell selection

Cell selection and reselection Siemens

MN1889EU11MN_0001 © 2005 Siemens AG

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Contents 1 Definition of adjacencies 3 1.1 General remarks 4 1.2 Parameters 6 2 Cell selection / cell reselection 9 2.1 General remarks 10 2.2 Parameters 16 3 Abnormal release of a TBF with cell reselection 17 3.1 General remarks 18 3.2 Parameters 19 4 Network controlled cell reselection 21 4.1 General remarks 22 4.2 Parameters 27 5 Traffic control strategy 29 5.1 General remarks 30 5.2 Parameters 36 6 Cell reselection (packet switched) from GSM to UMTS 39 6.1 General remarks 40 6.2 Parameters 42 7 Network controlled cell reselection to UMTS due to sufficient coverage 45 7.1 General remarks 46 7.2 Parameters 50 8 Network assisted cell change 55 8.1 General remarks 56 8.2 Parameters 60

Cell selection and reselection

Siemens Cell selection and reselection

MN1889EU11MN_0001© 2005 Siemens AG

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1 Definition of adjacencies



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1.1 General remarks NOTE Most of the parameters given in the definition of adjacent cells are corresponding to the settings of the cell itself. Therefore there is no difference between the meaning of the parameters in the different objects. The definition of neighbor cells in the BSC database is split into two objects: the ADJC object itself, and a TGTPTPPKF object, that is necessary for reference to cells that are handled by another BSC (external neighbors).

GSUP flag The GPRS Support attribute indicates whether or not the neighbor cell can be a target cell for GPRS cell reselection in case a PBCCH is configured in the serving cell. The status of this flag is not relevant if no PBCCH is created. Only if GSUP=TRUE the GPRS cell reselection parameters defined in the related PTPPKF object are broadcast in the PACKET SYSTEM INFORMATION TYPE 3 on the PBCCH. If a PBCCH is available, GPRS MS will not monitor the BCCH any more, i.e. the MS will only consider the information broadcast in the PACKET SYSTEM INFORMATION for cell reselection. This means that only if GSUP=TRUE the MS monitors the neighbor cell for GPRS cell reselection on the basis of the C31 criterion. If GSUP=FALSE and a PBCCH is configured, the neighbor cell will be ignored by the MS and no cell reselection to this neighbor cell will take place for any GPRS mobile. The parameters of the neighbor cell that are broadcast in the PACKET SYSTEM INFORMATION on the PBCCH are derived from the PTPPKF object associated to the neighbor cell as follows: 1. If the cell is an internal cell (i.e. belonging to the same BSC), the parameters are

derived from the PTPPKF object entered in the TGTCELL parameter. 2. If the cell is an external cell (i.e. belonging to a different BSC), the parameters

are derived from the TGTPTPPKF object entered in the TGTCELL parameter.



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TGTCELL= TGTCELL=internalneighbor

cells

external neighbor

cellsTGTBTS:n

TGTBTS:n/TGTPTPPKF:m

ADJC

BTSM:x/BTS:y/PTPPKF:n

BTSM:x/BTS:y

Fig. 1 Adjacent cell definition



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1.2 Parameters As mentioned above, the parameters for ADJC are identical to the parameters defined for the cells themselves and thus will be discussed there.

ADJC parameters: Parameter Range (default) Meaning GSUP TRUE, FALSE,

Default = FALSE This parameter defines whether or not GPRS is supported in the neighbor cell. Note: this parameter is only relevant if PBCCH is configured in the serving cell.

GTEMPOFF 0 .. 7, NULL Default = 1 step size: 10 dB 7 means infinity

GPRS_TEMPORARY_OFFSET applies a negative offset to C31 and C32 during runtime of the penalty timer.

GPENTIME 0 .. 31, NULL Default = 0 0 means 10 sec. … 31 means 320 sec.

GPRS_PENALTY_TIME defines the duration for which the GPRS Temporary Offset is applied in the C31 and C32 values of the cell reselection procedure.

GRESOFF 0 .. 31, NULL Default = 16 0: -52 dB 1: -48 dB ..... ...... 10: -12 dB 11: -10 dB ..... ...... 22: +12 dB 23: +16 dB ..... ...... 31: +48 dB

GPRS_RESELECT_OFFSET specifies the positive or negative offset and hysteresis to be applied to GPRS RESELECTION CRITERION in the mobile station.

GHCSTH 0..31; NULL Default = 10 Each step: 2dB 0 = -110 dBm, … 31 = -48 dBm

GPRS_HCS_THRESHOLD is the signal strength threshold for applying HCS GPRS re-selection.



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GHCSPC 0 .. 7, NULL Default = 3

GPRS_HCS_PRIORITY_CLASS defines the HCS priority which is used for the cell reselection procedure.

NCGRESOFF MDB52....DB48 Default = DB00 MDB52: -52 dB MDB51: -51 dB ..... ...... MDB01: -1 dB DB00: 0 dB ..... ...... DB48: +48 dB

This attribute specifies to mobile station the positive or negative offset and hysteresis to be applied to C32 value in the GPRS Network Controlled Cell Reselection procedure .

NCGTEMPOFF DB00 … DB60, NEVERDefault = DB00 The value NEVER means infinity.

This attribute applies a negative offset to C31 and C32 for the duration of NC_GPRS_PENALTY_TIME in the GPRS Network Controlled Cell Reselection Procedure.

NCGPENTIME SEC000...SEC320 Default = SEC000 SEC000: 0 seconds SEC001: 1 second SEC002: 2 seconds … SEC320: 320 seconds

This attribute gives the duration for which the NC_GPRS_TEMPORARY_OFFSET is applied in GPRS Network Controlled Cell Reselection procedure.

NCC1THADJC DB00...DB63 Default = DB05 DB00 0 dB DB01 1 dB .... DB63 63 dB

This attribute establishes the threshold concerning the C1 value for an adjacent cell.



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TGTPTPPKF parameters

Parameter Range (default) Meaning TGTPTPPKF NAME

pathname: TGTBTS:tgtbtsn/TGTPTPPKF:0 tgtbtsn: 0 .. 499

For every of the TGTBTS (0 .. 499) one TGTPTPPKF can be defined.

GRXLAMI 0 .. 63, Default = 6

GPRS_RXLEV_ACCESS_MIN is the minimum received level at MS side which is required to access a cell

GMSTXPMAC 0 .. 31, Default = 2

GPRS_MS_TXPWR_MAX_CCCH defines the maximum power which the MS may use on PBCCH and PCCCH. Values and meanings are the same as defined for the parameters MSTXPMAXGSM, MSTXPMAXDCS, and MSTXPMAXPCS.

RACODE 0 .. 255 The Routing Area Code identifies the routing area to which the cell belongs.

RACOL 0 .. 7 Default = 0

This parameter defines the Routing Area Color Code. Since a routing area (identified by its RACODE) can be smaller than a LA, and the RACODE is not unique in the network, but only in the LA, the RACOL parameter is used to choose the right RA when the mobile is listening to cells of different LA (containing routing area with the same code). The RA Color Code for the cells of the neighboring LA should therefore be set to a different value.



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2 Cell selection / cell reselection



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2.1 General remarks 2.1.1 No PBCCH exists According to GSM, if no PBCCH exists in the serving cell, GPRS cell selection / cell reselection is performed in the same way as for circuit-switched idle mode, that means it is controlled in this case by C1 and C2 : C1 = A - Max(B,0) A = RLA_C - RXLEV_ACCESS_MIN B = MS_TXPWR_MAX_CCH - P For the class 3 DCS 1800 MS: B = MS_TXPWR_MAX_CCH + POWER OFFSET - P RXLEV_ACCESS_MIN = Minimum received signal level at the MS required for access to the system. MS_TXPWR_MAX_CCH = Maximum TX power level a MS may use when accessing the system. POWER OFFSET = The power offset to be used in conjunction with the MS TXPWR MAX CCH parameter by the class 3 DCS 1 800 MS. P = Power class of the MS (Maximum RF output power of the MS). All values are expressed in dBm. For a suitable cell, C1 must be greater than 0.



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C2 is defined with the following formula: C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET * H(PENALTY_TIME - T) if PENALTY_TIME ≠ 31 C2 = C1 - CELL_RESELECT_OFFSET for PENALTY_TIME = 31 where • for non-serving cells:

H(x) = 0 for x < 0 H(x) = 1 for x ≥ 0

• for serving cells: H(x) = 0

T is a timer implemented for each cell in the list of strongest carriers. T shall be started from zero at the time the cell is placed by the MS on the list of strongest carriers, except when the previous serving cell is placed on the list of strongest carriers at cell reselection. In this, case, T shall be set to the value of PENALTY_TIME (i.e. expired). CELL_RESELECT_OFFSET, TEMPORARY_OFFSET, PENALTY_TIME and CELL_BAR_QUALIFY are optionally broadcast on the BCCH of the cell.



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2.1.2 PBCCH exists If a PBCCH exists, according to GSM the cell reselection is controlled by C1, C31 and C32. The cells to be monitored for cell re-selection are defined in the BA(GPRS) list, which is broadcast on PBCCH. If PBCCH does not exist, BA(GPRS) is equal to BA(BCCH). For a multi-RAT MS, cell re-selection to other radio access technologies shall also be possible. The MS shall measure the received RF signal level on the BCCH carriers of the serving cell and the surrounding cells as indicated in the BA(GPRS) list and calculate the received level average (RLA_P) for each carrier. RLA_P shall be a running average determined using samples collected over a period of 5 s, and shall be maintained for each BCCH carrier. The same number of measurement samples shall be taken for all BCCH carriers except, if the parameter PC_MEAS_CHAN indicates that the power control measurements shall be made on BCCH, for the serving cell where at least 6 measurement samples shall be taken per 52-multiframe. The samples allocated to each carrier shall as far as possible be uniformly distributed over the evaluation period. At least 5 received signal level measurement samples are required for a valid RLA_P value.



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In the following, (s) denotes the serving cell, and (ni) denotes the neighbor cells. The path loss criterion parameter C1 is used as a minimum signal level criterion for cell re-selection for GPRS in the same way as for GSM idle mode. Now, C1 is defined in the following way: C1 = A - Max(B,0) A = RLA_P - GPRS_RXLEV_ACCESS_MIN B = GPRS_MS_TXPWR_MAX_CCH - P The GPRS specific parameters GPRS_RXLEV_ACCESS_MIN and GPRS_MS_TXPWR_MAX_CCH for the serving cell and neighbor cells are broadcast on PBCCH of the serving cell (POWER OFFSET is not used).



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In addition to C1, a so-called signal level threshold criterion parameter C31 for hierarchical cell structures (HCS) is used to determine whether prioritized hierarchical GPRS cell re-selection shall apply: C31(s) = RLA_P(s) - HCS_THR(s) (serving cell) C31(n) = RLA_P(n) - HCS_THR(n) - TO(n) * L(n) (neighbor cell) where HCS_THR is the signal threshold for applying HCS GPRS re-selection. HCS_THR is broadcast on PBCCH of the serving cell. The cell ranking criterion parameter (C32) is used to select cells among those with the same priority and is defined by: C32(s) = C1(s) (serving cell) C32(n) = C1(n) + GPRS_RESELECT_OFFSET(n) - TO(n) * (1-L(n)) (neighb. cell) where GPRS_RESELECT_OFFSET applies an offset and hysteresis value to each cell, TO(n) = GPRS_TEMPORARY_OFFSET(n) * H(GPRS_PENALTY_TIME(n) - T(n)). L(n) = 0 if PRIORITY_CLASS(n) = PRIORITY_CLASS(s) L(n) = 1 if PRIORITY_CLASS(n) ≠ PRIORITY_CLASS(s) H(x) = 0 for x < 0 H(x) = 1 for x ≥ 0 GPRS_RESELECT_OFFSET, PRIORITY_CLASS, GPRS_TEMPORARY_OFFSET and GPRS_PENALTY_TIME are broadcast on PBCCH of the serving cell.



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2.1.3 Cell reselection algorithm The MS shall update RLA_P and calculate the value of C1, C31 and C32 for the serving cell and the non-serving cells. The MS shall make a cell re-selection if: • C1 for the serving cell falls below zero, or • a non-serving suitable cell is evaluated to be better than the serving cell. The best

cell is the cell with the highest value of C32 among those cells that have the highest PRIORITY_CLASS among those that fulfill the criterion C31 ≥ 0, or all cells, if no cells fulfill the criterion C31 ≥ 0.

If the parameter C32_QUAL is set, positive GPRS_RESELECT_OFFSET values shall only be applied to the neighbor cell with the highest RLA_P value of those cells for which C32 is compared above. PRIORITY_CLASS and C32_QUAL are broadcast on PBCCH of the serving cell. When evaluating the best cell, the following hysteresis values shall be subtracted from the C32 value for the neighbor cells: • in MM standby state, if the new cell is in the same routing area: 0. • in MM ready state, if the new cell is in the same routing area:

GPRS_CELL_RESELECT_HYSTERESIS. If the parameter C31_HYST is set, GPRS_CELL_RESELECT_HYSTERESIS shall also be subtracted from the C31 value for the neighbor cells.

• in MM standby or ready state, if the new cell is in a different routing area: RA_RESELECT_HYSTERESIS.

• in case of a cell re-selection occurred within the previous 15 seconds: 5 dB. GPRS_CELL_RESELECT_HYSTERESIS, C31_HYST and RA_RESELECT_HYSTERESIS are broadcast on PBCCH of the serving cell.



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2.2 Parameters The following parameters can be set in the PTPPKF object.

Parameter Range (default) Meaning GRXLAMI 0 .. 63,

Default = 6 GPRS_RXLEV_ACCESS_MIN is the minimum received level at MS side which is required to access a cell

GMSTXPMAC 0 .. 31, Default = 2

GPRS_MS_TXPWR_MAX_CCCH defines the maximum power which the MS may use when accessing a cell

GCELLRESH 0 .. 7, Default = 2

GPRS_CELL_RESELECT_HYSTERESIS applies an additional hysteresis to the C31 signal level threshold criterion

C31H TRUE, FALSE, Default = TRUE

the C31_HYST indicates whether or not GPRS_CELL_RESELECT_HYSTERESIS shall be applied to C31 for neighbor cells

C32QUAL TRUE .. FALSE,Default = FALSE

C32_QUAL indicates for certain situations whether or not GPRS_RESELECT_OFFSET shall be applied

RARESH 0 .. 7, Default = 2

the RA_RESELECT_HYSTERESIS is a hysteresis which is applied in MM STANDBY or READY state if the MS reselects a cell belonging to a different routing area

GHCSTH 0 .. 31, Default = 10

GPRS_HCS_THRESHOLD is the signal strength threshold for applying HCS GPRS re-selection. Each step: 2dB 0 = -110 dBm, ..., 31 = -48 dBm

GHCSPC 0 .. 7, Default = 3

GPRS_HCS_PRIORITY_CLASS defines the HCS priority which is used for cell reselection purpose

PCMECH MEABCCH, MEAPDTCH, Default = MEABCCH

PC_MEAS_CHAN indicates whether the MS measures the receive level downlink on BCCH or on PDCH for uplink power control purpose: MEABCCH: downlink measurements for power control are performed on BCCH; MEAPDTCH: downlink measurements for power control are performed on PDCH.



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3 Abnormal release of a TBF with cell reselection



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3.1 General remarks If access to another cell is allowed, i.e. the RANDOM_ACCESS_RETRY bit is set, the mobile station performs abnormal cell reselection and initiates establishment of an uplink TBF on the new cell. The mobile station shall not reselect back to the original cell for T_RESEL seconds if another suitable cell is available. The parameters RANDOM_ACCESS_RETRY and T_RESEL (default value 5 s) are broadcast in PSI 3. If access to another cell is not allowed, i.e. the RANDOM_ACCESS_RETRY bit is not set, or if no neighbor cells are available, the mobile station returns to the packet control channel and reports a RLC/MAC failure to the higher layer. The MS is under no circumstances allowed to access a cell to attempt abnormal cell reselection later than 20 seconds after the detection within the MS of the abnormal release causing the abnormal cell reselection attempt. In the case where the 20 seconds elapses without a successful abnormal cell reselection the attempt is abandoned.



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3.2 Parameters The following parameters can be set in the PTPPKF object.

RAARET TRUE, FALSE, Default = TRUE

The RANDOM_ACCESS_RETRY parameter defines whether or not random access retry to another cell is allowed in case of abnormal release.

TRESEL 0 .. 7, Default = 0

TRESEL defines how long a cell reselection is inhibited to a cell which was left with an abnormal release if another cell is available. 0 = 5 s 1 = 10 s 2 = 15 s 3 = 20 s 4 = 30 s 5 = 60 s 6 = 120 s 7 = 300 s



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4 Network controlled cell reselection



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4.1 General remarks Even if no handover functionality is foreseen for GPRS, the functionality of the network controlled cell re-selection exists. As the network has to decide about the target cell of a cell reselection, it needs some knowledge about the position of the MS. The network therefore may request measurement reports from the MS and control its cell re-selection. This is indicated by the parameter NETWORK_CONTROL_ORDER: • NC0: Normal MS control

The MS performs autonomous cell reselection. • NC1: MS control with measurement reports

The MS sends measurement reports to the network. The MS performs autonomous cell reselection.

• NC2: Network control The MS sends measurement reports to the network. The MS performs autonomous cell reselection only when the reselection is triggered by a downlink signaling failure or a random access failure.

The parameter values NC1 and NC2 only apply in MM Ready state. In MM Standby state, the MS always uses normal MS control independent of the ordered NC mode. GPRS mobiles in packet idle mode should work in NC0 mode, otherwise the network would have to manage the packet measurement reports and associated access requests needed by mobiles to transmit periodically packet measurement reports. Besides there are advantages on MS battery life time. Consequently NC2 should be used only for mobiles in packet transfer mode, while NC1 should not be used. The NC mode information is broadcast on SI13, if no GPRS control channel is present, or on PSI1 and PSI5, if a GPRS control channel is present. The broadcast mode is NC0; so every mobile in packet idle mode doesn’t transmit packet measurement reports to the BSC.



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Cell change

PCU

Fig. 2 Principle of Network Controlled Cell Reselection



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Network Controlled Cell Reselection procedure When a mobile is involved in a TBF (uplink or downlink), the BSC modifies the NC mode from NC0 to NC2 by a Packet Measurement Order message transmitted to that specific mobile on PACCH. This message carries also the info NC_Reporting_Period_T parameter (which overwrites the correspondent value optionally broadcast by PSI5), and the NC_Frequency_List.

After this change, the MS is working in NC2 control mode and transmits periodically Packet Measurement Report messages to the BSC. If the MS is involved in an uplink TBF, it uses blocks scheduled by the USF for the measurement report, while in a downlink TBF it uses blocks assigned with a RRBP field. If required, the BSC may transfer a MS to another cell by a Packet Cell Change Order command. This message contains the characteristics of the new cell that are necessary to identify it (i.e. BSIC + BCCH frequency) and the Network Controlled Cell Reselection measurement parameters valid for the mobile station in the new cell. Upon receipt of the PACKET CELL CHANGE ORDER message the mobile station starts timer T3174. When a network controlled cell reselection is performed, the mobile station immediately aborts any TBF in progress, if required. It stops all RLC/MAC timers except for timers related to measurement reporting. Then the MS switches to the identified new cell and performs the relevant RLC/MAC procedures in the new cell. The mobile station regards the cell change procedure as completed when it has received a successful response to its CHANNEL REQUEST or PACKET CHANNEL REQUEST message in the new cell.



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RACH (one phase)

Immediate Assignment

RLC Data Block

Packet Uplink Ack/Nack

RLC Data Block

Packet Measurement Order (NCO=2)

RLC Data Block

Packet Measurement Report

RLC Data Block


RLC Data Block (CV=0)


Packet Control Acknowledge

Packet Cell Change OrderMS start T3174and switch to indicated cell

RACH (one phase)

Immediate Assignment

RLC Data Block

RLC Data Block


RLC Data Block


NEW CELL

OLD CELL

MS startsto transmitin NCO = 0

MS passesto NCO = 2

MS BSC

MS stopsT3174

Packet Uplink Ack/Nack

Packet Uplink Ack/Nack (Final Ack)

Fig. 3 Call Flow for Network Controlled Cell Reselection



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Cell Reselection failure The MS returns to the old cell and starts the timer T3176 in case • the timer T3174 expires before a response to the CHANNEL REQUEST or

PACKET CHANNEL REQUEST message has been received in the new cell, or • an IMMEDIATE ASSIGNMENT REJECT or PACKET ACCESS REJECT message

is received from the new cell, or • the contention resolution procedure fails on the new cell. If the mobile station was in uplink packet transfer mode or in a simultaneous uplink and downlink packet transfer mode before the cell change, the mobile station establishes a new uplink TBF and sends the PACKET CELL CHANGE FAILURE message on this TBF (in the old cell). The mobile station then resumes its uplink data transfer on this new TBF. When the mobile station has sent a PACKET CELL CHANGE FAILURE message, timer T3176 is stopped. If T3176 expires and the mobile station was previously in an uplink packet transfer mode or in a simultaneous uplink and downlink packet transfer mode on the old cell, the mobile station performs an abnormal release with random access. If the mobile station was previously in a downlink packet transfer mode only on the old cell the mobile station performs an abnormal release. On the mobile station side, if the PACKET CELL CHANGE ORDER message instructs the mobile station to use a frequency that it is not capable to use, then the mobile station returns a PACKET CELL CHANGE FAILURE message with cause "frequency not implemented". If the PACKET CELL CHANGE ORDER message is received by the mobile while a circuit switched connection is on-going, then the mobile station returns a PACKET CELL CHANGE FAILURE message with the cause "on-going CS connection". NOTE The MS timer values T3174 and T3176 are fixed in the GSM recommendations. The values are

T3174: 15 sec. T3176: 5 sec.



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4.2 Parameters The network controlled cell reselection is handled by the following BSC parameter:

Parameter Range (default) Meaning NCRESELFLAG ENABLE, DISABLE

Default = DISABLE This parameter enables or disables the network controlled cell reselection feature.

The following parameters can be set in the PTPPKF object.

Parameter Range (default) Meaning NTWCOR NC0, NC1, NC2,

Default = NC 0 NETWORK_CONTROL_ORDER is the parameter which defines whether the MS or the network controls the cell reselection and whether or not the MS sends measurement reports

NTWCREPPIDL MSEC480, MSEC960, MSEC1920, MSEC3840, MSEC7680, MSEC15360, MSEC30720, MSEC61440 Default: MSEC61440

This parameter indicates the time period for cell reselection measurement reporting when the MS is in packet idle mode.

NTWCREPPTR MSEC480, MSEC960, MSEC1920, MSEC3840, MSEC7680, MSEC15360, MSEC30720, MSEC61440 Default: MSEC3840

This parameter indicates the time period for cell reselection measurement reporting when the MS is in packet transfer mode.

NTWCNDRXP NODRX, MSEC240, MSEC480, MSEC720, MSEC960, MSEC1200, MSEC1440, MSEC1920 Default: MSEC480

This parameter indicates the minimum time the mobile station shall stay in non-DRX mode after an NC measurement report has been sent.



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GNMULBAC 0 .. 3, NULL Default: NULL

This attribute specifies the minimum number of neighbor cells reported by MS not belonging to the frequency band of the serving cell.

NCSARA FALSE, TRUE Default: TRUE

This attribute NcSameRoutingArea, if set to TRUE, allows to prefer a network controlled cell selection to cells of the same routing area. In this case, the parameter NCRARESH should be set to 0 (DB00).

NCC1TH DB00, DB01, ... DB63 Default: DB03 (unit: dB)

The Network Controlled C1 Threshold defines a threshold concerning the C1 value: When a mobile has its C1 value below this threshold, it is moved to an adjacent suitable cell.

PKTMEASREPCNT 1 .. 10 Default: 1

This attribute indicates the number of consecutive serving cell’s BCCH carrier measurements under threshold NCC1TH , which are necessary to order a cell change.

NCRARESH DB00, ..., DB63 Default: DB00 [0 dB]

This attribute specifies the offset to apply to C32 of adjacent cell not belonging to the same routing area of serving cell. It has to be set to 0, when the NCSARA parameter is set to TRUE.



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5 Traffic control strategy



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5.1 General remarks Even if no handover functionality is foreseen for GPRS, the functionality of the network controlled cell re-selection has the same scope as the SBS feature 'handover due to traffic reason', i.e. the distribution of MS among cells according to network criteria. The network criterion is the optimum usage of resources, i.e. the better traffic distribution among the available channels in all the available cells, i.e. the max revenue for the operator for the GPRS packet data traffic.



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Cell change

....

congestion

PCU

Fig. 4 Principle of Network Controlled Cell Reselection



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When a mobile is involved into a packet data flow (packet transfer mode), the BSC modifies the Network Control Order value from NC0 to NC2. In addition, the time period is specified for transmitting NC measurement reports from the MS containing the appropriate receive levels. Then the MS periodically transmits packet NC measurement reports to the BSC. The NC measurement reports are used in the algorithm for the Network Controlled Cell Reselection. This takes also into account: • the number of configured channels for GPRS/EGPRS • the number of used channels for GPRS/EGPRS • whether channels are permanently reserved for GPRS/EGPRS or belong to a

common pool.

5.1.1 Network controlled cell reselection due to Um congestion On a timer basis the system checks if the radio resource occupation has reached or exceeded a configurable threshold (Cell_Res-Thres_OUT). In that case the system calculates MS candidates based on the cell reselection algorithm. As many MS are taken into account as radio resources are necessary to be released, in order to reduce the traffic load under the threshold (Cell_Res-Thres_OUT). The algorithm also determines cells, which accept incoming MS due to a configurable threshold (Cell_Res-Thres_IN) where the resource occupation must be lower than (Cell_Res-Thres_IN). Cells, which belong to the same PCU as the highly loaded cell from which this MS shall be redistributed, are candidates for cell reselection.



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• NCCR is activated only in packet transfer mode to avoid MR messages– NC2 is commanded by BSS with PMO message– Before the MS returns to the idle state, NC0 mode is restored with

another Packet Measurement Order message sent by the BSS

Fig. 5 NCR Activation



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5.1.2 Network controlled cell reselection due to Abis congestion

The BSC Call Processing handles dynamically • circuit switched channels (full-rate, half-rate and AMR), which require max. 1 x

16Kbit/s, • GPRS PDCH up to CS2, which require 1 x 16Kbit/s too, • GPRS PDCH up to CS3/CS4, which require 2 x 16Kbit/s, and • EGPRS PDCH (MCS1 – MCS9), which require up to 5 x 16Kbit/s. The BSC assigns single or multiple 16Kbit/s Abis resources from an Abis pool to air interface timeslots keeping into account: • Service type • Quality of Service Requirements for (E)GPRS • Abis/PCU resource congestion In case of (E-) GPRS, the initial Abis assignment can be changed dynamically during operation due to: • Radio Propagation Conditions of the Channels (Link Adaptation) • LOCK/SHUTDOWN/fault of SUBTSLB • Preemption of circuit switched services over packet switched services • Abis congestion Thresholds of Abis occupation can be defined to activate the features 'Cell load dependent activation of half rate' and 'HO due to radio resource management criteria'.



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CELL 1

BTSM1

TRFHITHABISTRFHITHR

TRFHITHABISTRFHITHR

TRFHITHABISTRFHITHR

TRFLTHABISTRFLTHR

TRFLTHABISTRFLTHR

CELL 2

BTSM2CELL 3

BTSM3

TRFLTHABISTRFLTHR

Fig. 6 Abis Congestion Thresholds

(Abis) Channels

Occupancy

FR

HR

ABISHRACTTHRHRACTT

Fig. 7 Abis Thresholds for HR activation



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5.2 Parameters The following parameter is set globally in the BSC object:

Parameter Range (default) Meaning TRFPS TRUE, FALSE

Default = FALSE This parameter defines the flag enabling the traffic control algorithm.

The following parameters can be set in the PTPPKF object:

Parameter Range (default) Meaning TRFPSCTRLT 1,2,….,100

Default: 5 This trafficPsControlTimer indicates the time period for the estimation of GPRS cell occupation.

CRESELTRHSOUT 50, 51 .. 100 Default: 85

This parameter defines the GPRS “occupation” threshold in percent: When the number of active GPRS MS is above this value, the network controlled cell reselection procedure can order GPRS MS to reselect another cell until the number of active GPRS MS is again below the threshold.

CRESELTRHSINP 0, 1, …, 85 Default: 75

This parameter defines the GPRS “occupation” threshold in percent: When the number of active GPRS MS is above this value, this cell cannot be ordered to be a target cell by network controlled cell reselection procedure.

NCTRFPSCTH 30, …, 100 Default = 75

This attribute indicates the threshold under which no other GPRS mobiles are ordered to change cell.



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The following parameters can be set in the BTSM object:

parameter value range meaning ABISHRACTTHR 0 .. 100, NULL

Default = 60 This parameter defines the threshold that indicates the percentage of busy Abis subslots (fully busy + half busy + out of service) in the Abis pool that triggers the Cell Load Dependent Activation of Half Rate in all the cells of the site where the feature is ENABLED.

ABISTRFHITHR 50 .. 100, NULL Default = 90

This parameter defines the Abis high traffic level threshold. In combination with the TRFHITH parameter, it is used to establish if handover for traffic reason has to be enabled/disabled. When the percentage of busy Abis subslots in the BTSM exceeds the value of the parameter, handover for traffic reason is ENABLED in all the BTS of the site for which TRFHOE is set to TRUE. In this case, if a handover for traffic reason is requested to BSC, it is performed towards a different BTSM.

ABISTRFLTHR 0 .. 80, NULL Default = 70

This parameter defines the Abis low traffic level to determine whether or not a BTSM can be a candidate to receive handover for traffic reason.



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6 Cell reselection (packet switched) from GSM to UMTS



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6.1 General remarks The inter-system cell reselection from GSM/GPRS to UMTS allows a packet switched connection which was started in the GSM/GPRS system to be delivered to the UMTS system. The principles for the packet switched cell reselection from GPRS to UMTS are the same as used for the circuit switched cell reselection from GSM to UMTS. In the following, the procedures and criteria by which the UE/MS decides to make this kind of inter-system change are analyzed. This cell reselection feature is important to guarantee a better quality connection when the mobile detects a stronger signal from a neighbor cell, even if this cell belongs to another Radio Access Technology (RAT). New UMTS operators who have not installed GPRS systems up to now, have to pay for the usage of GPRS networks of other operators and will therefore require GPRS to UMTS cell reselection in order to minimize their costs. Current GSM/GPRS operators do also require the GPRS to UMTS cell reselection in order to make best use of their UMTS islands. The principles of the cell reselection from GPRS to UMTS are displayed in the figure below.



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5sec

Qsearch

start WCDMA measurements

RLA_P of serving GSM cell

RSCP of WCDMAneighbor cell

RLA_P of (non serving) GSM neighbor cell

Cell Reselection(only if CPICH Ec/No is greater or equal GPRS_FDD_Qmin)

FDD_GPRS_Qoffset

Time

Fig. 8 Principle of the GPRS to UMTS cell reselection



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6.2 Parameters The following parameters can be set in the PTPPKF object:

Parameter Range (default) Meaning GUMTSSRHPRI TRUE,

FALSE, NULL, Default = NULL

The GPRS_UMTS_Search_Priority indicates whether or not GPRS-attached MS can search 3G cells when BSIC decoding is required, i.e. if the searching time can be longer than normal value (13 sec. instead of 10 sec. ).

GFDDQMI

MDB20, MDB18, MDB16, MDB14, MDB12, MDB10, MDB08, MDB06, NULL, Default = MBD12

The GPRS_FDD_Qmin is a threshold for signal Ec/No. If the FDD adjacent level carrier is higher than the serving cell + FDD_GPRS_Qoffset and Ec/No is higher than GFDDQMI, GPRS attached FDD_MS may select the adjacent FDD cell.

TDDGQO ALWAYS, MDB28, MDB24, MDB20, MDB16, MDB12, MDB08, MDB04, DB00, DB04, DB08, DB12, DB16, DB20, DB24, DB28, Default: DB00

The TDD_GPRS_Qoffset parameter indicates an offset which is applied for the carrier level of the TDD serving cell.

GFDDREPQTY

RSCP, Ec_No, NULL, Default = NULL

The GPRS_FDD_Reporting_Quantity parameter indicates the reporting quantity by GPRS-attached mobiles for UTRAN FDD cells.



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Parameter Range (default) Meaning GTDDMURREP

0...3 (step 1) NULL Default = NULL

The GPRS_TDD_Multirat_Reporting parameter indicates the number of TDD UTRAN cells to be included in the measurement reports by GPRS-attached mobiles.

GFDDMURREP

0...3 (step 1) NULL Default = NULL

The GPRS_FDD_Multirat_Reporting parameter indicates the number of FDD UTRAN cells to be included in the measurement reports by GPRS-attached mobiles.

QSRHPRI

UMDB98, UMDB94, UMDB90, UMDB86, UMDB82, UMDB78, UMDB74, ALWAYS, OMDB78, OMDB74, OMDB70, OMDB66, OMDB62, OMDB58, OMDB54, NEVER, Default = NEVER

The Qsearch_Priority parameter defines a threshold and indicates whether the measurements have to be made by the mobile when the signal is under or above the threshold; the value is expressed in dB.

FDDGQO

ALWAYS, MDB28, MDB24, MDB20, MDB16, MDB12, MDB08, MDB04, DB00, DB04, DB08, DB12, DB16, DB20, DB24, DB28, Default: DB00

The FDD_GPRS_Qoffset parameter indicates an offset which is applied for the carrier level of the serving GPRS cell and suitable non-serving GPRS cell(s).



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Parameter Range (default) Meaning GFDDRSCPMI

MDB115, MDB113, MDB111, MDB109, MDB107 MDB105, MDB103, MDB101, MDB099, MDB097, MDB095, MDB093, MDB091, MDB089, MDB087, MDB085 Default = MDB101

The GPRS_FDD_RSCP_MIN is a threshold for signal RSCP. If the FDD adjacent level carrier is higher than the serving cell + FDD_GPRS_Qoffset and RSCP is higher than GFDDRSCPMI, GPRS attached FDD_MS may select the adjacent FDD cell.

GFDDQMIO

DB00, DB02, DB04 DB06, DB08, DB10, DB12, DB14 Default = DB00

The GPRS_FDD_Qmin_Offset is an offset subtracted from GPRS_FDD_Qmin in the cell reselection process.



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7 Network controlled cell reselection to UMTS due to sufficient coverage



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7.1 General remarks As discussed above cell reselection from GSM to UMTS during packet transfer is possible in mobile controlled cell reselection mode. In network controlled cell reselection mode reselection within the 2.5G network is possible and it is used to distribute traffic within the BSC area. Both mechanisms can be combined. When a UMTS cell adjacent to the GSM cell can provide sufficient coverage for a MS the network can order the MS to change from the GSM serving cell to the UMTS target cell. The UE/MS has to perform the measurements of the adjacent UMTS cells and has to report them to the GSM network by periodically sending PACKET MEASUREMENT REPORT messages to the BSS. The number of FDD and TDD neighboring cells that the UE/MS adds to the PACKET MEASUREMENT REPORT depends on the values of the GPRS_FDD_MULTIRAT_REPORTING and the GPRS_TDD_MULTIRAT_REPORTING parameters that can be defined by the operator. Network Controlled (NC) cell reselection from GSM/GPRS (including EGPRS) to UMTS can be enabled/disabled via the EnableUmts_SuffCov_NC_Resel parameter.

Reselection algorithm The Network Controlled Cell Reselection (NCCR) algorithm is initiated in the BSC for UE/MSs that are in the packet transfer mode. The BSC evaluates the periodically incoming PACKET MEASUREMENT REPORT messages from the UE/MS. The NCCR to UMTS for a TDD neighboring cell is initiated when the level of the Received Signal Code Power (RSCP) measured for the TDD cell is larger than the UmtsSuff_RSCP_NC_Resel threshold that can be set by the operator. For a FDD neighboring cell the threshold depends on the GPRS_FDD_REPORT_QUANT parameter. For RSCP reporting, the NCCR to UMTS is initiated when the received level of the RSCP measured for the FDD cell is larger than the UmtsSuff_RSCP_NC_Resel threshold that can be set by the operator. For Ec/No-reporting, the NCCR to UMTS is initiated when the measured received quality (Ec/No) of the FDD cell is higher than the value of the UmtsSuff_EcNo_NC_Resel threshold that can also be set by the operator.



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PCU

GSM/GPRS cell GSM/GPRS cell

UMTS cell

Cell change

Fig. 9 Principle of Network Controlled Cell Reselection to UMTS



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UMTS cell ranking in the Target Cell List (TCL) UMTS neighboring cells that fulfill the above described threshold conditions are included in a Target Cell List (TCL). TDD cells and FDD cells are ranked separately in TDD and FDD sublists. TDD cells in the TDD sublist are ranked according to the level of the RSCP; i.e. the TDD cell with the largest RSCP is placed at the top of the TDD sublist. FDD cells in the FDD sublist are ranked according to the level of the RSCP or according to the received Ec/No quality, depending on the GPRS_FDD_REP_QUANT operator defined parameter. If RSCP reporting is used, the FDD cell with the largest RSCP is placed at the top of the FDD sublist. If Ec/No-reporting is used, the FDD cell with the largest Ec/No is placed at the top of the FDD sublist. To form the complete UMTS TCL, the FDD sublist is sorted before the TDD sublist.

Packet Cell Change Order The BSC includes the UMTS cell, which was placed at the top of the UMTS TCL, into the PACKET CELL CHANGE ORDER message. By sending this message to the UE/MS the BSC requests that the UE/MS perform a cell reselection to this UMTS cell.

Mobile Speed Sensitive (MSS) NCCR G->U The EnableUmts_MSS_NC_RESEL parameter makes it possible to enable/disable the “Mobile Speed Sensitivity” of the NCCR G->U algorithm. When enabled, the NCCR G->U is performed for a “fast moving” UE/MS only under certain conditions: A timer (Timer_UE_Speed) and a micro cell identifier (GPRS_microcell_Umts) can be defined for each UMTS neighboring cell of a GSM cell; i.e. these 2 parameters can be specifically set for UMTS neighboring cells by the operator. The MSS NCCR G->U algorithm is only applied for those UMTS neighboring cells that are defined as micro cells (GPRS_microcell_Umts = TRUE). The timer is started for an UE/MS when the “sufficient” threshold condition for the NCCR G->U algorithm is met. GSM/GPRS cell reselection to this UMTS micro cell is thus inhibited for the UE/MS until the timer expires. A UMTS micro cell is only added to the UMTS TCL for the NCCR G->U handover, when the “sufficient” threshold condition is met during the whole timer period. Logically, a “fast moving” UE/MS violates this timer condition and therefore, the NC cell reselection from a GSM/GPRS serving cell to this UMTS micro cell is not initiated for “fast moving” UE/MSs.



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GSM/GPRS cells

UMTS cells

Fast moving MS/UE -> no cell reselection

Slow moving MS/UE -> cell reselection

Fig. 10 Speed sensitivity of the Network Controlled Cell Reselection to UMTS



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7.2 Parameters The following parameters have to be configured per BSC:

Parameter Range (default) Meaning EUSCNCRESEL TRUE, FALSE

Default: FALSE The enableUmtsSuffCovNcResel attribute is used to enable or disable this feature. Note that if the feature is enabled, the already existing NCRESELFLAG attribute of the BSC must also be enabled.

The following parameters have to be configured per ADJC3G:

Parameter Range (default) Meaning USRSCPNCRESEL

0, …, 63 Default = 8 for FDD Default = 18 for TDD The values are based on the scale: 0: RSCP < -115 dBm 1: -115 <= RSCP < -114 dBm2: -114 <= RSCP < -113 dBm… 62: -54 <= RSCP < -53 dBm 63: -53 <= RSCP < -52 dBm

This attribute defines the “sufficient” RSCP threshold used by the BSC to control the initiation of the reselection. It can be set for each UMTS neighboring cell (FDD or TDD) of a GSM cell. It is always used for TDD cells, for FDD cells it is used only when the FDD_REP_QUANT attribute is set to "RSCP" reporting.

USECNONCRESEL

0, …, 49 Default: 19 Scale: 0: Ec/Io < -24 dB 1: -24 <= Ec/Io < -23.5 dB 2: -23.5 <= Ec/Io < -23 dB … 48: -0.5 <= Ec/Io < 0 dB 49: 0 <= Ec/Io

The umtsSuffEcNoNCResel attribute defines the “sufficient” Ec/No threshold used by the BSC to control the initiation of NCCR G->U. It can be specifically defined for reporting purposes for each FDD neighboring cell of a GSM cell.



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Parameter Range (default) Meaning GMICROCU TRUE, FALSE

Default: FALSE The gprsMicrocellUmts attribute describes whether or not a UMTS neighboring cell is a UMTS microcell to which the additional MSS condition of the Mobile Speed Sensitive (MSS) reselection algorithm applies.

TUESP 0, …, 100 Default: 5 (seconds)

The timerUeSpeed is used for Mobile Speed Sensitive (MSS) cell reselection. The timer is started for an MS/UE when the threshold condition for "sufficient UMTS coverage" is met. Network controlled GSM/GPRS cell reselection to the specific UMTS microcell is inhibited for the MS/UE until this timer has expired. A UMTS microcell is only included in the UMTS TCL when the threshold condition for "sufficient UMTS coverage" is met during the whole timer period. A "fast moving" MS/UE violates this timer condition and therefore, NC cell reselection from a GSM/GPRS serving cell to the UMTS microcell is not performed for "fast moving" MSs/UEs.

The following parameters have to be configured per TGTFDD/TGTTDD:

Parameter Range (default) Meaning MSTXPMAXUMTS

0, …, 19 Default = 9 Scale: 0: 43 dBm 1: 41 dBm … 19: 5 dBm

The msTxPwrMaxUmts parameter indicates the maximum level of transmission power a MS is allowed to use in the serving cell for UMTS.



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The following parameters have to be configured per PTPPKF:

Parameter Range (default) Meaning EUMSSNCRESEL TRUE, FALSE

Default: FALSE This attribute is used to enable or disable the “Mobile Speed Sensitivity” of the network controlled GSM/GPRS to UMTS cell reselection.

GFDDREPQTY RSCP, Ec_No, NULL Default = NULL

The GPRS_FDD_Reporting_Quantity parameter indicates the reporting quantity by GPRS-attached mobiles for UTRAN FDD cells.

GFDDMURREP 0, ..., 3, NULL Default = NULL

The GPRS_FDD_Multirat_Reporting parameter indicates the number of FDD UTRAN cells to be included in the measurement reports by GPRS-attached mobiles.

GTDDMURREP 0, ..., 3, NULL Default = NULL

The GPRS_TDD_Multirat_Reporting parameter indicates the number of TDD UTRAN cells to be included in the measurement reports by GPRS-attached mobiles.

QSRHPRI UMDB98, UMDB94, UMDB90, UMDB86, UMDB82, UMDB78, UMDB74, ALWAYS,OMDB78, OMDB74,OMDB70, OMDB66,OMDB62, OMDB58,OMDB54, NEVER Default = NEVER

The Qsearch_Priority parameter defines a threshold and indicates whether the measurements have to be made by the mobile when the signal is under or above the threshold; the value is expressed in dB.

GUMTSSRHPRI TRUE, FALSE, NULL Default = NULL

The GPRS_UMTS_Search_Priority indicates whether or not GPRS-attached MS can search 3G cells when BSIC decoding is required, i.e. if the searching time can be longer than normal value (13 sec. instead of 10 sec.).



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TFAILNCU 0, …, 100 Default: 5 (seconds)

The TimerFailNcUmts is used when the BSC has received a PACKET CELL CHANGE FAILURE message (containing an UMTS cell description) from a UE/MS. The particular UMTS neighboring cell is excluded from the UMTS TCL until this timer expires.

MAFAILNCU 0, …, 100 Default = 4

The maxFailNcUmts attribute specifies the maximum number of reselection retries for the same UMTS neighboring cell to a UE/MS, in case the ordered cell change to this UMTS neighboring cell fails.

TBNCU 0, …, 100 Default = 5 (seconds)

The BSC starts the TimeBackNcUmts for a UE/MS that is in the packet transfer mode and has been relocated to a GSM/GPRS cell. Until it expires, the NC cell reselection from GSM/GPRS to UMTS is inhibited for the UE/MS. This timer avoids fast “ping-pong” back cell reselection to the UMTS network.

The following parameters have to be configured per CPCU:

Parameter Range (default) Meaning T5 2, …, 29

Default = 10 Unit = sec.

This timer defines the waiting time for a response from the SGSN after sending a RA-CAPABILITY-UPDATE PDU.

NRACPBLUPDRET 1, …, 30 Default = 3

This parameter defines the maximum number of retries in the RA-CAPABILITY-UPDATE procedure.



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8 Network assisted cell change



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8.1 General remarks The goal of this feature is to support the MS with the Network Assisted Cell Change procedures, providing certain system information of the target cell before performing cell change. When the MS has to reselect a new cell with NACC support, it delays the reselection and it enters in CCN (Cell Change Notification) mode, then it invokes NACC by proposing a target cell to the BSC. The BSC evaluates the target cell proposed by the MS, since it may approve the proposed cell or may indicate another one, then it provides the system information related to the new cell. In order to perform this evaluation the BSC takes into account radio and traffic parameters. NACC procedure assists the MS also after the cell change, providing the required missing SI/PSI.

Cell Change Notification Mode In the cells where this feature is activated a new parameter called CCN_ACTIVE is broadcast. It indicates whether CCN is enabled in the cell or not. If a MS is camping on a cell where CCN is implemented (CCN_ACTIVE=1) it may access NACC support. In order to do this it has to be aware of neighbor cells where CCN is supported. This information is related to the cells in the neighbor cell list and is reported via the CCN_SUPPORTED parameter. When CCN_SUPPORTED is not present but CCN is enabled in the serving cell, the mobile station assumes that CCN is enabled towards all neighbor cells. If this MS determines that a cell re-selection towards one of its neighboring cells is required, it will first check the corresponding CCN_SUPPORTED parameter, if available. If this is true for the target cell of the cell reselection procedure (i.e. the cell is handled by the same BSC) the MS enters CCN mode and sends a Packet Cell Change Notification message to the BSS. Otherwise (external neighbor) it makes the reselection without NACC support. To request assistance from the network, the MS sends a Packet Cell Change Notification message to inform the network that the cell-reselection criteria are now fulfilled. This message carries the BSIC and the ARFCN as identity for the proposed cell as well as the measurement reports for the proposed cell and for other neighbor cells if available. The data transfer continues in the old cell until the network takes a decision and transmits the chosen target cell to the mobile. On the Network side the NACC algorithm starts when the Packet Cell Change Notification message arrives to the PPXU



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MS

Packet Cell Change NotificationCCN

Mode

DATA Transfer

Packet Cell Change Continue orPacket Cell Change Order

Packet Control Ackn. (Cell Change)

Packet Neighbour Cell Data

BSC

Fig. 11 Initial signaling flow for network assisted cell change

MS

Packet PSI/SI Status

Packet Serving Cell Data

BSC

Fig. 12 Subsequent signaling flow after network assisted cell change



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NACC decision If the proposed cell has an acceptable Path_Loss (C1>NCC1TH) and is going to a not congested cell the NACC algorithm accepts the cell proposed by the MS. If the Path_Loss is unacceptable (C1<= NCC1TH) or the target cell is congested the algorithm evaluates another cell (if available). The SI of the selected cell is contained in one or more instances of the PACKET NEIGHBOUR CELL DATA message. If there are no acceptable cells, the NACC algorithm gives no response to the MS, and the timers in the MS (fixed to 1 second) allow the mobile to continue the cell reselection in NC0/NC1 mode. If the cell selected is the same proposed by the MS the network send a Packet Cell Change Continue, if it is a different one a Packet Cell Change Ordered is sent. When the mobile station receives one of these messages it has to transmit a PACKET CONTROL ACKNOWLEDGMENT message in the specified uplink radio block if a valid RRBP field is received as part of the message; before it switches to the new cell.

Acquisition of missing system information In the new cell the MS indicates with a Packet PSI/SI Status message the (packet) system information which is missing. The network then will deliver this requested information to the MS.



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Packet Cell Change Notification received with

list of target cells

Path loss acceptable ?

Cell congested ?

Yes

No

Remove cell fromlist of target cells

Yes

No

List empty ?

Yes

No

Try next cell fromlist of target cells

Send Neighbour Cell Data

Cell = MS proposed cell ?

Yes

No

Send Packet CellChange Order

Send Packet CellChange Order

Fig. 13 Decision algorithm for network assisted cell change



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8.2 Parameters The following parameters have to be configured per BSC:

Parameter Range (default) Meaning CCHANTFACT TRUE, FALSE

Default: FALSE The CellChangeNotificationActive attribute indicates whether CCN is enabled in the BSC or not.

SYSPACKSYSSUP TRUE, FALSE Default: FALSE

The value of this parameter indicates if the PACKET PSI STATUS and PACKET SI STATUS messages are supported or not in the BSC.

NACCNTWCOR NC0, NC1 Default = NC0

This attribute defines the usage of Network Control Order during NACC when MS is in Packet transfer Mode. When NACC is enabled, the value of this attribute is put in the parameter Network Control Order inside Packet Measurement Order message.

The following parameters are defined in the CPCU:

Parameter Range (default) Meaning T3 1, .., 100,

Default = 50 Unit = 100msec

This timer defines the waiting time for a response from the SGSN after sending a SUSPEND PDU.

T4 1, .., 100, Default = 10 Unit = 100msec

This timer defines the waiting time for a response from the SGSN after sending a RESUME PDU.

05 mn1889eu11mn 0001 cell selection

Documents

packet idle

busy abis

packet transfer

mm ready state

mm standby

packet system

gprs attached

active gprs