2g 3g cell reselection alcatel

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

3 CELL RESELECTION FROM 2G TO 3G The algorithm is described in the 3GPP TS05.08. As the Alcatel UTRAN may be neighboured with a BSS of any constructor, we start with 3GPP description, then we focus on Alcatel B8 and B9 BSS implementation.

A multi-RAT UE camping on 2G, or attached to GPRS on 2G may measure 3G cells. Reselection of the 3G cells may be under control of the UE or the network.

The main function of the GMM sub-layer is to support the mobility of user terminals, such as informing the network of its present location and providing user identity confidentiality.

In GMM Standby state, and packet idle mode, cell-reselection is performed by UE. In GMM Ready state, cellreselection is either performed by UE or controlled by network. This is indicated by the parameter NETWORK_CONTROL_ORDER. The meaning of the different parameter values is specified as follows: NC0 Normal MS controls The MS shall perform autonomous cell re-selection.

NC1

MS control with measurement reports The MS shall send measurement reports to the network.

The MS shall perform autonomous cell re-selection.

NC2

Network control The MS shall send measurement reports to the network.

The MS shall only perform autonomous cell re-selection when the reselection is triggered by a downlink signalling failure or a random access failure.

RESET

The MS shall return to the broadcast parameters. Only sent on PCCCH or PACCH.

The parameter values NC1 and NC2 only apply in Ready state. In Standby state, the MS shall always use normal MS control independent of the ordered NC mode.

3.1 CELL RESELECTION FROM 2G TO 3G UNDER UE CONTROL

At SGSN level, the UE is either in: • Idle state, the subscriber is not attached to the SGSN. • GMM Standby state (the UE is not transmitting data), • GMM Ready State (the UE is transmitting data or has just transmitted data) and NETWORK_CONTROL_ORDER=NC0 or NC1.

The algorithm is the same in idle or attached to GPRS, only parameters change.

3.1.1 IN GMM IDLE STATE

The UE in GMM idle state monitors SI (System Information) broadcast on the BCCH.

UE measurements on the serving cell in idle

For the purposes of cell selection and reselection, the UE is required to maintain an average of received signal levels for all monitored frequencies. These quantities termed the "received level averages" (RLA_C), shall be unweighted averages of the received signal levels measured in dBm.

3DF 01900 0000 PTZZA – DIAMS

The network controls the measurements for reselection of 3G cells by the parameter Qsearch_I broadcast on BCCH. Qsearch_I defines a threshold and also indicates whether these measurements shall be performed when RLA_C of the serving cell is below or above the threshold. These measurements may be performed less frequently than measurements of GSM cells, in order to conserve UE power.

UE in idle searches for 3G cells: • Either when RLA_C of the serving cell is below Qsearch_I, Qsearch_I belongs to [-98dBm; -74dBm], • Or when RLA_C of the serving cell is above Qsearch_I, Qsearch_I belongs to [-78dBm; -54 dBm], • Or always, • Or never.

ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

19/77

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

UE measurements on 3G neighbour cells

UE reads FDD UTRAN neighbour UARFCN from System Information 2ter or 2quater broadcast on the BCCH depending on BSS constructor. SI2quater lists scrambling codes of the FDD neighbour cell, while SI2ter does not. If the 3G Cell Reselection list includes UTRAN frequencies, the UE shall, at least every 5 s update the value RLA_C for the serving cell and each of the at least 6 strongest non-serving GSM cells.

A multi-RAT UE shall be able to monitor 64 FDD cells on up to 3 FDD frequencies, with a maximum of 32 cells per frequency.

The UE shall be able to identify and select a new best UTRAN cell on a frequency, which is part of the 3G Cell Reselection list, within 30 seconds after it has been activated under the condition that there is only one UTRAN frequency in the list and under good radio conditions (hypothesis for good radio conditions in 3GPP TS0508: CPICH Ec/Io = -10.4 dB, CPICH RSCP = -70 dBm). The allowed time is increased by 30 seconds for each additional UTRAN frequency in the 3G Cell Reselection list. However, multiple UTRAN cells on the same frequency in the list do not increase the allowed time.

2G to 3G cell reselection criteria

The UE shall reselect a suitable UTRAN cell (as defined in 2.1) if: CPICH Ec/No > FDD_Qmin

and

CPICH RSCP > RLA_C + FDD_Qoffset for the serving cell and all of the suitable non-serving GSM cells for a period of 5 seconds.

In case of a cell reselection occurring within the previous 15 seconds, FDD_Qoffset is increased by 5 dB. Where: - CPICH Ec/No (dB) and CPICH RSCP (dBm) are the FDD quantities measured by UE. - RLA_C (dBm) is the 2G quantity measured by UE. - FDD_Qmin and FDD_Qoffset are broadcast on BCCH of the serving cell: - FDD_Qmin: minimum threshold for UTRAN FDD cell reselection, - FDD_Qoffset: applies an offset to RLA_C.

Note: The parameters required to determine if the UTRAN cell is suitable are broadcast on BCCH of the UTRAN cell. A UE may start reselection towards the UTRAN cell before decoding the BCCH of the UTRAN cell, leading to a short interruption of service if the UTRAN cell is not suitable.

Cell reselection to UTRAN shall not occur within 5 seconds after the UE has reselected a GSM cell from an UTRAN cell if a suitable GSM cell can be found.

If more than one UTRAN cell fulfils the above criteria, the UE shall select the cell with the greatest RSCP value.

3.1.2 IN GMM STANDBY STATE OR GMM READY STATE

If PBCCH is activated and the UE is PBCCH-capable, the UE in GMM standby or ready state monitors PSI (Packet System Information) broadcast on the PBCCH.

Otherwise, the UE in GMM standby or ready state monitors SI (system information) broadcast on the BCCH; and procedures in [7] shall apply.

UE measurements on the serving cell

3DF 01900 0000 PTZZA – DIAMS

The UE 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 optionally the NC_FREQUENCY_LIST, and calculate the received level average (RLA_P) for each carrier.

The network controls the measurements for reselection of 3G cells by the parameter Qsearch_P broadcast on PBCCH. Qsearch_P defines a threshold and also indicates whether these measurements shall be performed when RLA_P of the serving cell is below or above the threshold.

UE attached to GPRS searches for 3G cells: • Either when RLA_P of the serving cell is below Qsearch_P, Qsearch_P belongs to [-98dBm; -74dBm], ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

20/77

Or when RLA_P of the serving cell is above Qsearch_P, Qsearch_P belongs to [-78dBm; -54 dBm], Or always, Or never.

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

• • •

UE measurements on 3G neighbour cells

If the GPRS 3G Cell Reselection list includes UTRAN frequencies, the UE shall, at least every 5 second update the value RLA_P for the serving cell and each of the at least 6 strongest non-serving GSM cells.

For a multi-RAT UE, cells or frequencies with other radio access technologies may also be included in the GPRS 3G Cell Reselection list to be monitored. This list may be modified by PACKET MEASUREMENT ORDER or PACKET CELL CHANGE ORDER messages. It provides the UE with: • FDD UTRAN neighbour UARFCN(s) • Optionally, FDD UTRAN neighbour Scrambling Codes.

A multi-RAT UE shall be able to monitor 64 FDD cells on up to 3 FDD frequencies, with a maximum of 32 cells per frequency.

At BSS level, the UE attached to GPRS is either: • In packet transfer mode (BSS mode where the mobile is transmitting data), • Or in packet idle mode (BSS mode where the mobile is not transmitting data).

In packet transfer mode, the UE shall be able to send the first access at the latest 5+x seconds after a new best UTRAN cell, which is part of the GPRS 3G Cell Reselection list, has been activated under the condition that there is only one UTRAN frequency in the list and that no new GSM cells are activated at the same time and under good radio conditions. x is the longest time it may take to receive the necessary system information in the new cell. The allowed access time is increased by 5 seconds for each additional UTRAN frequency in the GPRS 3G Cell Reselection list and by the time required for BSIC decoding of new activated GSM cells. However, multiple UTRAN cells on the same frequency in the list do not increase the allowed access time.

In packet idle mode, the UE shall be able to identify and select a new best UTRAN cell on a frequency, which is part of the GPRS 3G Cell Reselection list, within 30 seconds after it has been activated under the condition that there is only one UTRAN frequency in the list and under good radio conditions (hypothesis for good radio conditions in 3GPP TS0508: CPICH Ec/Io = -10.4 dB, CPICH RSCP = -70 dBm) . The allowed time is increased by 30 seconds for each additional UTRAN frequency in the GPRS 3G Cell Reselection list. However, multiple UTRAN cells on the same frequency in the list do not increase the allowed time.

For this monitoring, the MS may use search frames that are not required for BSIC decoding or interference measurements in packet transfer mode. If indicated by the parameter 3G_SEARCH_PRIO, the MS may use up to 25 search frames per 13 seconds without considering the need for BSIC decoding or packet transfer mode interference measurements in these frames.

In GMM ready state, in B9, a 2G to 3G cell reselection can be done. It is transparent to the UTRAN: UE and CN are re-establishing the service on 3G. Nevertheless, this is disabled per default, as this degrades the performances on 2G (measuring also 3G). This cannot be “fast” mobility and this is the reason, why today this feature is not activating on the commercial networks.

2G to 3G cell reselection criteria

The UE shall reselect a suitable UTRAN cell (as defined in 2.1) if: CPICH Ec/No >FDD_Qmin And

CPICH RSCP > RLA_P + FDD_GPRS_Qoffset for the serving cell and all of the suitable non-serving GSM cells for a period of 5 seconds.

3DF 01900 0000 PTZZA – DIAMS

In case of a cell reselection occurring within the previous 15 seconds, FDD_GPRS_Qoffset is increased by 5 dB. Where • CPICH Ec/No (dB) and CPICH RSCP (dBm) are the FDD quantities measured by UE. • RLA_P (dBm) is the 2G quantity measured by UE. • FDD_Qmin and FDD_GPRS_Qoffset are broadcast on PBCCH of the serving cell: • FDD_Qmin: minimum threshold for UTRAN FDD cell reselection, ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

21/77

•

FDD_GPRS_Qoffset: applies an offset to RLA_P.

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

Note: The parameters required to determine if the UTRAN cell is suitable are broadcast on BCCH of the UTRAN cell.

Cell reselection to UTRAN shall not occur within 5 seconds after the UE has reselected a GSM cell from an UTRAN cell if a suitable GSM cell can be found.

If more than one UTRAN cell fulfils the above criteria, the UE shall select the cell with the greatest RSCP value.

3.2 CELL RESELECTION FROM 2G TO 3G UNDER NETWORK CONTROL

The UE is in GMM Ready state (at SGSN level) and NETWORK_CONTROL_ORDER=NC2. When PBCCH is not activated or the UE is not PBCCH capable, the UE reads BCCH and CCCH. Otherwise, the UE reads PBCCH and PCCCH. The network specifies to the UE which measurements are expected through parameters broadcast on BCCH/PBCCH or sent individually to the UE on CCCH/PCCCH or PACCH (Packet Cell Change Order or Packet Measurement Order), in which case it overwrites the broadcast parameters. The individual parameters are valid until the RESET command is sent to the UE or there is a downlink signalling failure or the UE goes to the Standby state or the UE enters dedicated mode.

Based on reported measurements, a cell re-selection command (Cell Change Order) may be sent from the network to the UE. The command may include re-selection of another radio access technology/mode. When the UE receives the command, it shall re-select the cell according to the included cell description and change the network control.

Algorithm to trigger cell-reselection based on UE measurements is BSS constructor dependent. As Alcatel BSS B8 does not support it for inter-RAT cells, there is no further description.

The cell reselection from 2G to 3G under network control feature allows the network also to perform a handover of a packet switched connection from GPRS to UMTS. It uses the inter-RAT Cell Reselection / inter-RAT Cell Change Order procedures to UTRAN: GPRS and UMTS R99 PS domain do not support the Handover/Relocation procedures that are defined for the CS domain.

Inter-RAT Cell Change Order procedure is defined in TS 25.331. This procedure is initiated by GPRS in a cell operating in NC2 mode by sending a cell change order to the UE, in which the identity of the target UTRAN cell is specified. Decision is taken by GPRS based on its knowledge of UTRAN adjacent cells and UE inter-RAT measurement reports is requested.

The UE initiates a cell reselection procedure via the establishment of a new RRC connection to UTRAN.

The UTRAN receives a RRC CONNECTION REQUEST message from the UE with Establishment Cause ‘inter-RAT cell reselection’ or ‘inter-RAT cell change order’ and handles it like any other Establishment Cause. Both RRC connection requests are associated with indicator (RRC_connect_req_interRAT).

From the UTRAN point of view, whereas there is only one single PS RAB or multiple PS RAB, the procedure is handled in the same way.

3DF 01900 0000 PTZZA – DIAMS

The 2G to 3G cell reselection works well without needing the scrambling code.

ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

22/77

3.3 PARAMETERS, THEIR RANGE AND CODING

above

below

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

3.3.1 QSEARCH_I, QSEARCH_P 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

= -98 dBm = -94 dBm = -90 dBm = -86 dBm = -82 dBm = -78 dBm = -74 dBm ∞ (always) = -78 dBm = -74 dBm = -70 dBm = -66 dBm = -62 dBm = -58 dBm = -54 dBm ∞ (never)

Table 7: Qsearch_I and Qsearch_P coding values

Qsearch_I is sent in system information SI 2ter or SI 2quater (BCCH) depending on BSS constructor.

The default UE value if Qsearch_I is not sent in system information is 15 (never).

When Qsearch_I=7 (infinity), UE shall always measure 3G cells.

Qsearch_P is sent in system information Packet SI 3 quarter (PBCCH), or PACKET MEASUREMENT ORDER or PACKET CELL CHANGE ORDER messages.

3.3.2 FDD_QMIN

FDD_Qmin is sent in system information SI 2ter or SI 2quater depending on BSS constructor. FDD_Qmin is sent in system information Packet SI 3 quarter or PACKET MEASUREMNT ORDER or PACKET CELL CHANGE ORDER messages.

The default UE value if FDD_Qmin is not sent in system information is 7 (-12 dB).

3DF 01900 0000 PTZZA – DIAMS

0 1 2 3 4 5 6 7

= -20 dB = -6 dB = -18 dB = -8 dB = -16 dB = -10 dB = -14 dB = -12 dB Table 8: FDD_Qmin coding values

FDD_Qmin should be consistent with Qqualmin introduced in 2.1cell selection criteria.

Consistently rule will be detailed in the document on Parameters, but for sure, FDD_Qmin>Qqualmin.

ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

23/77

The recommended setting for 2G in case of 2G to 3G cell reselection is the following: FDD_Qmin = -10 dB Qsearch_I = 7 (infinity), resulting that UE always measures 3G All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

FDD_Qoffset = 0

3.3.3 FDD_QOFFSET AND FDD_GPRS_QOFFSET 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

− ∞

= -28 dB = -24 dB = -20 dB = -16 dB = -12 dB = -8 dB = -4 dB = 0 dB = 4 dB = 8 dB = 12 dB = 16 dB = 20 dB = 24 dB = 28 dB

(always select a cell if acceptable)

Table 9: FDD_Qoffset and FDD_GPRS_Qoffset coding values

FDD_Qoffset is sent in system information SI 2ter or SI 2quater depending on BSS constructor. The default UE value if FDD_Qoffset is not sent in system information is 8 (0 dB).

FDD_GPRS_Offset is sent in system information Packet SI 3 quarter or PACKET MEASUREMENT ORDER or PACKET CELL CHANGE ORDER messages.

FDD_Qoffset and FDD_GPRS_Qoffset should be consistent with Qoffset_snGSM introduced in 2.5 cell reselection criteria.

3.4 IMPLEMENTATION IN ALCATEL B8 BSS OF CELL RESELECTION FROM 2G TO 3G

In Idle and GMM Standby state, the cell reselection is under UE control. In GMM Ready state, either the cell reselection is under UE control or there is no cell reselection possible from 2G to 3G.

Alcatel B8 BSS does not advise 3G cells measurements while the UE is in Packet Transfer Mode (implies GMM Ready state). Indeed, the UE could interrupt its data transfer frequently for monitoring 3G neighbour cells and a degradation of throughput is observed while the UE is performing measurements on 3G cells.

Alcatel B8 BSS only enables mobile autonomous GSM to UMTS cell reselection. NC2 is not available for interRAT cells, thus preventing the multi-RAT UE from for searching for UMTS FDD cells while the UE is in GMM ready state and in NC2 mode.

3G search deactivation introduced in Alcatel BSS B8 prevents the multi-RAT UE from searching for UMTS FDD cells while the UE is in GMM ready state and in NC0 mode.

3DF 01900 0000 PTZZA – DIAMS

The drawing below basically represents the different states of a UE attached to GPRS:

ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

24/77

GMM Standby state All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

Packet Idle Mode

GMM Ready state

Beginning of transfer Ready timer expiration

Packet Transfer Mode End of transfer

Packet Idle Mode Figure 5: GMM states transitions in GPRS

Below the algorithm, which determines, if 3G-search is activated in GMM Ready state or not:

The UE in Packet Transfer Mode is in Ready state, if NETWORK_CONTROL_ORDER= • NC0, if EN_2G_TO_3G_CELL_RESELECTION= • “Enable with 3G search activated while the UE is in GMM ready state“, UE perform measurements on 3G cells even during the transfer. 3G cell reselection is also possible during the transfer.

• “Enable with 3G search deactivated while the UE is in GMM ready state”, when the UE enters Packet Transfer Mode, it receives a PACKET MEASUREMENT ORDER message from BSS, which overwrites the value of Qsearch_P or Qsearch_I broadcast in the SI2TER or PSI3QUATER messages by a Qsearch set to “never”. 3G cell reselection will be possible when the UE leaves the Ready state.

• NC2, the 3G-search is systematically deactivated when activating the NC2 mode through Packet Measurement Order. When transfer ends, if NC2_DEACTIVATION_MODE= • “NC2 deactivation at the expiry of the GMM Ready timer”, no Packet Measurement order is sent at the end of the transfer, NC0 applies when the UE leaves Ready state at the ready timer expiration, then 3G cell reselection becomes possible.

• “NC2 deactivation at the end of the packet transfer”, a Packet Measurement order is sent at the end of the transfer to deactivate NC2, NC0 applies, 3G cell reselection becomes possible whatever the setting for EN_2G_TO_3G_CELL_RESELECTION (except “Disabled”). UE stays in Ready state until the ready timer expires.

3DF 01900 0000 PTZZA – DIAMS

If EN_2G_TO_3G_CELL_RESELECTION takes the value “Disabled”, SI2ter, PSI3quater do not broadcast 3G cells, Packet Measurement Order does not include 3G cells. 2G to 3G reselection is not possible, except if the UE leaves the 2G coverage and performs a cell selection procedure.

ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

25/77

3.4.1 B8 BSS PARAMETERS FOR 3G CELL RESELECTION

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

Parameter

Comment

FDD_Qoffset

Offset added to the received level average of the serving cell and of the neighbour GSM cells for UTRAN FDD cell re-selection.

FDD_Qmin Minimum threshold for Ec/Io for UTRAN FDD cell reselection.

Qsearch Threshold for searching for 3G cells depending whether the received level average of the serving cell is below or above the threshold.

In a cell with FDD_ARFCN_list not empty, Qsearch =-70, i.e. always search for 3G neighbour cells.

NETWORK_CON Defines whether the UE or the TROL_ORDER BSS controls the cell reselections.

Domain

Range

Step

Access Example

GSM cell

-32 to 28 dB -32= -∞ (always select a cell if acceptable)

1

RNO

-32= -∞

GSM cell

-20 to -6 dB

2

RNO

-12 dB

GSM cell

Below: -98 to –70 dBm -70= ∞(always) Above: -78 to –50 dBm -50= ∞ (never)

4

RNO

+∞

GSM cell

0: NC0 2: NC2 for R99 onwards UE 3: NC2 for all UE 0: NC2 deactivation at the end of the packet transfer, PMO is sent 1: NC2 deactivation at the expiry of the GMM Ready timer, PMO is not sent 0: Disabled 1: Enabled with 3G search activated while the UE is in GMM ready state 2: Enabled with 3G search deactivated while the UE is in GMM ready state 0 to 3276,6

enum

RNO

0

enum

RNO

0

enum

RNO

2

0.2 MHz

RNO

10786

NC2_DEACTIVATI Defines whether or not the GSM cell ON_MODE Packet Measurement Order with a Reset Command is sent at the end of a packet transfer.

EN_2G_TO_3G_ Enables/Disables the GSM to CELL_RESELECTI UTRAN FDD cell reselections ON and defines the 3G-search activation mode for MS in GMM Ready state.

GSM cell

3DF 01900 0000 PTZZA – DIAMS

FDD_ARFCN_LIST List of neighbour FDD UTRAN BSS frequencies 0 = 0.0 MHz, 1 = 0.2 MHz, ... , 16383 = 3276.6 MHz. The value of “-1” indicates that no UTRAN frequency is provided.

FDD_Qmin is broadcast in SI2ter on BCCH and in PSI 3quater on PBCCH if there is a PBCCH allocated and activated in the serving cell.

FDD_Qoffset is broadcast in SI2ter on BCCH (FDD_Qoffset) (FDD_GPRS_Qoffset) if there is a PBCCH allocated in the serving cell.

ED

02

and

in

PSI

3quater

RELEASED

R4 3G-2G algorithms_ed02.doc

on

PBCCH

003 2006-10-05

3DF 01900 3411 VAZZA

26/77

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

Qsearch is broadcast in SI2ter on BCCH (Qsearch_I) and in PSI 3quater on PBCCH (Qsearch_P) if there is a PBCCH allocated and activated in the serving cell.

3.5 IMPLEMENTATION IN ALCATEL B9 BSS OF CELL RESELECTION FROM 2G TO 3G 3.5.1 ISSUES OF B8, TAKEN INTO ACCOUNT IN B9 AND B9 REQUIREMENTS Issue I1: “SI2TER limitations”

The scheduling period of the 3G cell reselection parameters and frequencies is higher when they are transmitted in SI2TER than when they are conveyed on SI2QUATER. Indeed, a single occurrence of an SI2TER message can contain only one UARFCN; instead a single occurrence of an SI2QUATER message may contain a list of UARFCN.

Requirement 1: UTRAN FDD neighbourhood information conveyed in SI2QUATER on BCCH

On BCCH, the SI2QUATER message coding is more efficient than SI2TER then it allows the MS to acquire and to refresh more quickly its knowledge of the 3G neighbouring cells information. Then, on BCCH, the neighbour UTRAN FDD cells shall be provided in SI2QUATER (new message). SI2QUATER message shall be sent on the Extended BCCH if the operator has enabled the Extended BCCH, otherwise on the Normal BCCH. Requirement 1R1 complies with R99Release 4: in R99Release 4, the 3GPP standard offers 2 ways of broadcasting the 3G neighbour cells: either the SI2TER or SI2QUATER.

Issue I2: “3G coverage”

The 3G coverage is not necessarily the same as the 2G one, it could exist areas covered by one BSS without being covered with 3G technology.

The FDD frequencies are described at BSS level and the 2G to 3G cell reselection is enabled at BSC level. So, FDD frequencies are broadcast on any cell managed by the BSC, even for GSM cells having no 3G neighbouring, thus leading to waste of time for UE/MS camping on such cells. The implementation of a flag, at GSM cell level, enabling or not the 2G to 3G cell reselection could avoid such waste of time.

In B9 there are some requirements that must be taken into account:

Requirement 2: Enabling 2G to3G cell reselection on a per GSM cell basis

The FDD frequencies defined at BSS level are broadcast (SI2TER, SI2QUATER and PSI3QUATER) only in the GSM cells where 2G to 3G cell reselection is enabled

3.5.2 B9 FEATURES UTRAN FDD neighbourhood information conveyed in SI2QUATER on BCCH The SI2QUATER is sent (Requirement 1) in an Evolium serving cell if:

i) The O&M parameter EN_2G_TO_3G_CELL_RESELECTION is set to “Enabled with 3G search activated while the UE/MS is in GMM ready state” or “Enabled with 3G search deactivated while the UE/MS is in GMM ready state” for that cell (Requirement 2) and ii) There is at least one UTRAN FDD neighbour frequency to describe

3DF 01900 0000 PTZZA – DIAMS

The SI2TER is sent in a non Evolium serving cell if:

i) The O&M parameter EN_2G_TO_3G_CELL_RESELECTION is set to “Enabled with 3G search activated while the UE/MS is in GMM ready state” or “Enabled with 3G search deactivated while the UE/MS is in GMM ready state” for that cell (Requirement 2) and ii) There is at least one UTRAN FDD neighbour frequency to describe The PSI3QUATER is sent in a serving cell if:

ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

27/77

3DF 01900 0000 PTZZA – DIAMS

All rights reserved. Passing on and copying of this document, use and communication of its contents not permitted without written authoriziation from Alcatel.

i) The O&M parameter EN_2G_TO_3G_CELL_RESELECTION is set to “Enabled with 3G search activated while the UE/MS is in GMM ready state” or “Enabled with 3G search deactivated while the UE/MS is in GMM ready state” and ii) There is at least one UTRAN FDD neighbour frequency to describe

The SI2QUATER message (Requirement 1R1), which is sent on the BCCH, conveys:

ED

02

RELEASED

R4 3G-2G algorithms_ed02.doc

003 2006-10-05

3DF 01900 3411 VAZZA

28/77