Dual Transfer Mode b 10

ED 01 RELEASED DUAL TRANSFER MODE

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Site VELIZY

EVOLIUM SAS

Originators R. MAUGER

DUAL TRANSFER MODE

System : ALCATEL GSM BSS Sub-system : SYS-TLA Document Category : PRODUCT DEFINITION

ABSTRACT This SFD describes the "DUAL TRANSFER MODE" feature. This feature allows a dual transfer mode capable MS to use a radio resource for CS traffic and simultaneously one or several radio resources for PS traffic.

Approvals Name App.

R. MAUGER SYT Manager

E. ZORN PL

J.-P. GRUAU PM


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REVIEW Ed. 01 Proposal 03 2006/02/10 MRD/TD/SYT/rma/0060.2006

HISTORY Ed. 01 Proposal 01 2005/10/28 First proposal based on Ed1 RL of the SFD DTM written for B9

(3BK 10204 0604 DTZZA), for alignment with B10 step 2 specifications. In particular, it takes into account : Change of instance for EN_DTM (from BSS to cell) Description of interactions between DTM and GPRS QoS Update of PM counters (MFS and BSC)

Ed.01 Proposal 02 2005/12/02 Update according to review report MRD/TD/SYT/rma/0413.2005 Update of OMC, SED impacts according to information provided by sub-systems.

Ed. 01 Proposal 03 2006/01/09 Update according to review report MRD/TD/SYT/rma/0017.2006 Alignment with B10 step 2 specifications :

No support of RT PFC in DTM Alignment of counters list and names with MFS counters

catalogue Ed. 01 Released 2006/02/10 Update according to review report MRD/TD/SYT/rma/0060.2006


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TABLE OF CONTENTS

1 INTRODUCTION...........................................................................................................................................9 1.1 Scope 9 1.2 Document structure.............................................................................................................................9 1.3 Definitions and pre-requisite..............................................................................................................9

2 HIGH-LEVEL DESCRIPTION .....................................................................................................................10 2.1 Functional Requirements..................................................................................................................10

2.1.1 Overview....................................................................................................................................10 2.1.2 Activation of the feature.............................................................................................................10 2.1.3 Support of Gs interface..............................................................................................................10 2.1.4 Half rate .....................................................................................................................................10 2.1.5 EGPRS ......................................................................................................................................10 2.1.6 Inter-cell handovers ...................................................................................................................10 2.1.7 Intra-cell handovers ...................................................................................................................11 2.1.8 Hierarchical networks ................................................................................................................11 2.1.9 Extended cells ...........................................................................................................................11 2.1.10 Support of GPRS QoS...............................................................................................................11

2.2 Overall description of the proposed solutions...............................................................................11 2.3 Compliance to the marketing requirements ...................................................................................12 2.4 Compliance to 3GPP standard .........................................................................................................12 2.5 Working assumptions .......................................................................................................................13 2.6 Dependencies ....................................................................................................................................13 2.7 HW Coverage......................................................................................................................................14 2.8 Decision criteria.................................................................................................................................15

2.8.1 Standardisation..........................................................................................................................15 2.8.2 Competition ...............................................................................................................................15 2.8.3 Customer ...................................................................................................................................15 2.8.4 Gains .........................................................................................................................................15

2.8.4.1 Telecom gains..........................................................................................................................15 2.8.4.2 Operational gains.....................................................................................................................15

2.8.5 Risks ..........................................................................................................................................15 3 SYSTEM IMPACTS.....................................................................................................................................17

3.1 Telecom ..............................................................................................................................................17 3.1.1 Functional-level description.......................................................................................................17

3.1.1.1 (De)activation of the dual transfer mode feature .....................................................................17 3.1.1.2 Broadcast of (packet) system information ...............................................................................17 3.1.1.3 Monitoring the RR operating of the MS ...................................................................................18 3.1.1.4 Paging co-ordination in the BSS..............................................................................................18 3.1.1.5 MS contexts shared between the MFS and the BSC ..............................................................20 3.1.1.6 Radio resource management ..................................................................................................21

3.1.1.6.1 Supported DTM multislot classes ....................................................................................21 3.1.1.6.2 CS call multiplexing on TCH............................................................................................23 3.1.1.6.3 TBFs multiplexing on PDCHs ..........................................................................................24 3.1.1.6.4 Maximizing the number of consecutive PDCHs ..............................................................24 3.1.1.6.5 Sharing of the radio resources between the BSC and the MFS .....................................25 3.1.1.6.6 TBF re-allocations for MS operating in DTM ...................................................................26 3.1.1.6.7 Interactions between DTM and QoS ...............................................................................26

3.1.1.7 Interactions with NC2 mode and CCN mode...........................................................................27 3.1.1.8 Power control management .....................................................................................................27 3.1.1.9 Timing advance management..................................................................................................27 3.1.1.10 GPRS transparent transport protocol...................................................................................27 3.1.1.11 Signalling protocol changes .................................................................................................28


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3.1.1.11.1 DTM mode .......................................................................................................................28 3.1.1.11.2 New signalling procedures in the CS domain for DTM....................................................28

3.1.1.11.2.1 Reassignment of the signalling channel from SDCCH to TCH .............................28 3.1.1.11.2.2 Modification of a TCH channel mode from "signalling only" to "speech" or "data".29

3.1.1.11.3 Connection establishments .............................................................................................30 3.1.1.11.4 Connection releases ........................................................................................................31 3.1.1.11.5 Handovers when in dedicated mode ...............................................................................31 3.1.1.11.6 Handovers in dual transfer mode ....................................................................................32

3.1.1.12 MS Classmark handling .......................................................................................................34 3.1.2 Telecom Specification impacts..................................................................................................35

3.1.2.1 System Information management............................................................................................35 3.1.2.2 DTM Functional Specification ..................................................................................................35

3.1.2.2.1 Radio link establishment in the BSC ...............................................................................35 3.1.2.2.2 Normal assignment in the BSC .......................................................................................35 3.1.2.2.3 Internal channel change in the BSC................................................................................35 3.1.2.2.4 External channel change in the BSC...............................................................................35 3.1.2.2.5 Channel Modification in the BSC.....................................................................................36 3.1.2.2.6 Call release in the BSC....................................................................................................36 3.1.2.2.7 Power control ...................................................................................................................36 3.1.2.2.8 DTM operation in the MFS...............................................................................................36 3.1.2.2.9 DTM operation in the BTS ...............................................................................................36

3.1.2.3 Classmark handling .................................................................................................................36 3.1.2.4 Resource allocation and management ....................................................................................36 3.1.2.5 Handover preparation ..............................................................................................................36 3.1.2.6 Packet System Information ......................................................................................................36 3.1.2.7 Radio resource management Packet resource handling .....................................................37 3.1.2.8 GPRS - Radio interface MAC layer ......................................................................................37 3.1.2.9 GPRS - Radio interface RLC layer .......................................................................................37 3.1.2.10 BSCGP.................................................................................................................................37 3.1.2.11 BSS Telecom parameters ....................................................................................................37 3.1.2.12 MFS counters catalogue ......................................................................................................37 3.1.2.13 BSC counters catalogue.......................................................................................................37 3.1.2.14 Layer 3 Air interface catalogue ............................................................................................37 3.1.2.15 Layer 3 Abis interface catalogue..........................................................................................37 3.1.2.16 Layer 3 A interface catalogue ..............................................................................................37 3.1.2.17 LCS & (E)GPRS Telecom presentation ...............................................................................37

3.1.3 Interfaces...................................................................................................................................38 3.1.3.1 Radio interface.........................................................................................................................38 3.1.3.2 Abis interface ...........................................................................................................................38 3.1.3.3 A interface ................................................................................................................................38 3.1.3.4 Gb interface..............................................................................................................................38 3.1.3.5 BSCGP interface......................................................................................................................38 3.1.3.6 GCH interface ..........................................................................................................................39

3.2 Operation and maintenance .............................................................................................................39 3.2.1 OMC-R parameters ...................................................................................................................39 3.2.2 Modelisation of OMC-R parameters..........................................................................................40

3.2.2.1 OMC GDMO impacts ...............................................................................................................40 3.2.2.2 ACIE Interface impacts ............................................................................................................40 3.2.2.3 OMC-BSC interface impacts....................................................................................................40 3.2.2.4 OMC-MFS interface impacts....................................................................................................40

3.2.3 Other parameters ......................................................................................................................40 3.2.4 PM counters ..............................................................................................................................41 3.2.5 PM indicators.............................................................................................................................42 3.2.6 Migration....................................................................................................................................42

3.2.6.1 OMC migration.........................................................................................................................42 3.2.6.2 BSC migration ..........................................................................................................................42 3.2.6.3 MFS migration..........................................................................................................................42

3.2.7 Java scripts................................................................................................................................43


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3.2.8 Fault Management.....................................................................................................................43 3.2.9 O&M Specification impacts .......................................................................................................43

3.2.9.1 Step 2 A .................................................................................................................................43 3.2.9.2 Step 2 B .................................................................................................................................43

3.3 Validation............................................................................................................................................43 3.3.1 Testing tools ..............................................................................................................................43 3.3.2 Test strategy..............................................................................................................................43

3.3.2.1 System tests coverage.............................................................................................................43 3.3.2.2 Overall strategy for system tests..............................................................................................43

3.4 Methods ..............................................................................................................................................46 3.5 GCDs 46 3.6 Engineering rules ..............................................................................................................................46

4 SUBSYSTEM IMPACTS.............................................................................................................................47 4.1 BTS 47 4.2 BSC 47

4.2.1 DTM Activation/Deactivation .....................................................................................................47 4.2.2 BSC Shared DTM Information...................................................................................................47 4.2.3 MFS shared DTM information ...................................................................................................47 4.2.4 Enter/Leave DTM mode ............................................................................................................47 4.2.5 DTM Request ............................................................................................................................48 4.2.6 DTM assignment .......................................................................................................................48 4.2.7 DTM packet Notification ............................................................................................................48 4.2.8 MS (in Dedicated mode) TCH handover ...................................................................................48 4.2.9 MS (in Dedicated mode) SDCCH handover..............................................................................48 4.2.10 MS (in DTM mode) handover ....................................................................................................49 4.2.11 GTTP .........................................................................................................................................49 4.2.12 Assignment Request procedure ................................................................................................49 4.2.13 Clear Command ........................................................................................................................49 4.2.14 State Handling in BSC call buffer ..............................................................................................49 4.2.15 Radio Resource Management...................................................................................................50 4.2.16 Classmark handle......................................................................................................................50 4.2.17 Power Control Management......................................................................................................50 4.2.18 Cell State change/Response, BSC State Change/Response...................................................50 4.2.19 Abnormal Case..........................................................................................................................51

4.3 Transcoder .........................................................................................................................................51 4.4 MFS 51 4.5 OMC-R.................................................................................................................................................51

4.5.1 HMI impacts...............................................................................................................................51 4.5.2 Optional feature .........................................................................................................................52 4.5.3 Overview of the impact upon OMC specs.................................................................................52

4.5.3.1 The DFS LCM ..........................................................................................................................52 4.5.3.2 The OMC3 Form for Key Generator (KeyGEN).......................................................................52

4.6 LASER.................................................................................................................................................52 4.7 MPM/NPA/RNO...................................................................................................................................52 4.8 Polo 52 4.9 OEF 52

5 PERFORMANCE & SYSTEM DIMENSIONING.........................................................................................53 5.1 Traffic model ......................................................................................................................................53 5.2 Performance.......................................................................................................................................53 5.3 Load constraints................................................................................................................................53

6 OPEN POINTS ............................................................................................................................................54 7 IMPACTS SUMMARY.................................................................................................................................55 8 GLOSSARY ................................................................................................................................................56

8.1 Abbreviations.....................................................................................................................................56 8.2 Terminology .......................................................................................................................................56


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9 ANNEX A: 3GPP STANDARD REMINDER...............................................................................................57 9.1 DTM mobile station capabilities.......................................................................................................57

9.1.1 Singleslot and multislot operations............................................................................................57 9.1.2 Support of EGPRS ....................................................................................................................57 9.1.3 Multislot configurations for dual transfer mode .........................................................................57 9.1.4 Differences between 3GPP release 1999, release 4 and release 6 .........................................58

9.2 Common ID procedure ......................................................................................................................59 9.3 Paging co-ordination for GPRS........................................................................................................59 9.4 Radio resource operating modes and mobility management states ...........................................60 9.5 GPRS Transparent Transport Protocol ...........................................................................................60 9.6 Usage of main DCCH with SAPI = 0.................................................................................................61

9.6.1 Usage of the main DCCH for GPRS signalling at MS side .......................................................62 9.6.2 Usage of the main DCCH for GPRS signalling at BSS side .....................................................62 9.6.3 Format of LAPDm frames..........................................................................................................62

9.7 (Packet) system information monitoring while in dual transfer mode.........................................62 9.8 Discontinuous reception (DRX) .......................................................................................................63 9.9 Dual transfer mode information field element in the Old BSS to New BSS information IE.......63 9.10 Mobility management ........................................................................................................................64 9.11 Suspend/Resume procedure............................................................................................................64

9.11.1 GPRS suspension for MS in class B mode of operation...........................................................64 9.11.2 GPRS suspension for dual transfer mode not supported .........................................................64

9.12 Comparison between PSI13 and PSI14 ...........................................................................................65 10 ANNEX B: MAIN SCENARIOS ..................................................................................................................67

10.1 CS establishment while in packet idle mode..................................................................................67 10.1.1 Establishment of a MO CS connection while in packet idle mode ............................................67 10.1.2 Establishment of a MT CS connection while in packet idle mode.............................................68 10.1.3 Intra-cell handovers when in dedicated mode...........................................................................68 10.1.4 Intra-BSC inter-cell handovers when in dedicated mode..........................................................69 10.1.5 Inter-BSC inter-cell handovers when in dedicated mode..........................................................70

10.2 PS establishment while in dedicated mode....................................................................................71 10.3 CS establishment while in uplink packet transfer mode...............................................................75 10.4 CS establishment while in downlink packet transfer mode..........................................................79 10.5 PS establishment while in dual transfer mode...............................................................................81 10.6 CS connection release while in dual transfer mode ......................................................................81 10.7 PS connection release while in dual transfer mode ......................................................................83 10.8 Intra-BSC inter-cell handover while in dual transfer mode...........................................................84 10.9 Inter-BSC inter-cell handover while in dual transfer mode...........................................................86 10.10 GPRS Transparent Transport Protocol ...............................................................................89 10.11 GPRS suspension in cells not supporting dual transfer mode ........................................90

11 ANNEX C: SUPPORT OF GPRS QOS (FUTURE IMPROVEMENT) ........................................................91


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TABLE OF FIGURES Figure 1: Supported (2+2) timeslot configurations .......................................................................................... 22 Figure 2: Supported (3+2) timeslot configurations. ......................................................................................... 23 Figure 3: Examples of a TCH shared by two HR CS calls. ............................................................................. 24 Figure 4: Examples of a DTM PDCH shared by several MSs......................................................................... 24 Figure 5: RR operating modes and transitions for a DTM capable MS. ......................................................... 60 Figure 6: Transmission of an LLC PDU on the main DCCH ........................................................................... 61 Figure 7: Format of LAPm frames. .................................................................................................................. 62 Figure 8: Establishment of a MO CS connection while in packet idle mode................................................... 68 Figure 9: Intra-cell handover when in dedicated mode. .................................................................................. 68 Figure 10: Traffic TCH to traffic TCH intra-BSC inter-cell handover when in dedicated mode....................... 69 Figure 11: Traffic TCH to traffic TCH inter-BSC inter-cell handover when in dedicated mode....................... 70 Figure 12: Establishment of a MO PS session while in dedicated mode with reallocation of the CS resource.

.................................................................................................................................................................. 71 Figure 13: Establishment of a MT PS session while in dedicated mode and in GMM ready state. The old

TCH is re-assigned................................................................................................................................... 73 Figure 14: Establishment of a MT PS session while in dedicated mode and in GMM ready state. The old

TCH is not re-assigned............................................................................................................................. 74 Figure 15: Establishment of a MT PS session while in dedicated mode and in GMM standby state. ............ 75 Figure 16: Establishment of a CS connection while the MS is in uplink packet transfer mode. ..................... 76 Figure 17: TCH assignment request received while a DTM request is under process................................... 78 Figure 18: Establishment of a CS connection while the MS is in downlink packet transfer mode.................. 81 Figure 19: CS connection release while in dual transfer mode with on-going UL TBF (case MSC initiating the

normal CS connection release)................................................................................................................ 82 Figure 20: CS connection release while in dual transfer mode with on-going DL TBF (case MSC initiating the

normal CS connection release)................................................................................................................ 83 Figure 21: PS connection release while in dual transfer mode. ...................................................................... 84 Figure 22: Intra-BSC inter-cell handover while in dual transfer mode (case of TCH to TCH handovers). ..... 85 Figure 23: Inter-BSC inter-cell handover while in dual transfer mode (case of TCH to TCH handovers). ..... 88 Figure 24: Transport of an UL LLC PDU with GTTP....................................................................................... 89 Figure 25: Transport of a DL LLC PDU with GTTP......................................................................................... 89 Figure 26: GPRS suspension in a cell that does not support dual transfer mode. ......................................... 90


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INTERNAL REFERENCED DOCUMENTS Not applicable

REFERENCED DOCUMENTS Alcatel references [ 1] 3BK 10204 0609 DTZZA, SFD: Autonomous packet resource allocation [ 2] 3BK 10204 0605 DTZZA, SFD: Support of QoS in the BSS [ 3] 3DC 25339 0046 DRZZA, MFD: Dual Transfer Mode [ 4] 3BK 10204 0632 DTZZA, SFD: A956 RNO BSS B9 [ 5] 3BK 10204 0025 DTZZA, SFD: Extended dynamic allocation

3GPP references [ 6] 3GPP TS 43.055 3GPP TS Group GERAN, Dual Transfer Mode, Stage 2, Release 6 [ 7] 3GPP TS 45.002 3GPP TS Group GERAN, Multiplexing and multiple access on the radio path,

Release 6 [ 8] 3GPP TS 45.008 3GPP TS Group GERAN, Radio subsystem link control, Release 6 [ 9] 3GPP TS 24.008 3GPP TS Group CN, Mobile radio interface Layer 3 specification, Core network

protocols, Stage 3, Release 6 [ 10] 3GPP TS 44.060 3GPP TS Group GERAN, GPRS MS-BSS interface, RLC/MAC protocol,

Release 6 [ 11] 3GPP TS 44.018 3GPP TS Group GERAN, Mobile radio interface layer 3 specification, RRC

protocol, Release 6 [ 12] 3GPP TS 48.008 3GPP TS Group GERAN, MSC-BSS interface layer 3 specification, Release 6 [ 13] 3GPP TS 23.060 3GPP TS Group SA, GPRS Service description, Stage 2, Release 6 [ 14] 3GPP TS 43.064 3GPP TS Group GERAN, Overall description of the GPRS radio interface,

Stage 2, Release 6 [ 15] 3GPP TS 44.064 3GPP TS Group CN, MS-SGSN LLC layer specification, Release 6 [ 16] 3GPP TS 48.018 3GPP TS Group GERAN, GPRS BSS-SGSN interface, BSS GPRS protocol,

Release 6

PREFACE This document is the input paper for the feature DUAL TRANSFER MODE inside TD. It will further on be used as reference for the development of that feature in each subsystem.


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1 INTRODUCTION

1.1 Scope The present document aims to be the basis for decision of a proposed change to be made on the BSS system. It provides all necessary information related to functional description, gains, description of the system impacts and subsystem impacts. This document does not describe the support of DTM multislot class 11. Description of this feature can be found in ref.[ 5].

1.2 Document structure The section 2 of this document presents: the functional requirements, an overall description of the features, the compliance to marketing requirements and to the 3GPP standard, which working assumptions have been made and the dependencies, as well as some decision criteria such as the risk, the gain, etc associated to the features addressed by

the present SFD.

The section 3 identifies the system impacts : it gives the principles and presents the functional split of the feature between subsystems. The interactions within the BSS between the various modules, layers, etc are shown as well as the interaction with the other Network Elements. Impacts on telecom and O&M Step2 specifications are also given in this section. The validation strategy is presented as well as the impacts on GCD, methods and engineering rules.

The section 4 recaps the impacts for each subsystem.

The section 5 addresses the performance and system dimensioning concerns.

The section 6 identifies and describes the open points that have been raised in the various reviews.

The section 7 is a sum up of the system impacts.

The section 8 contains the glossary of the present document.

Annex A contains a description of the 3GPP standard features related to the dual transfer mode.

Annex B presents the main scenarios related to the dual transfer mode feature.

1.3 Definitions and pre-requisite Annex A defined the main terms introduced by the 3GPP standard to describe the dual transfer mode feature. It also presents the main changes introduced by the dual transfer mode feature in the 3GPP standard.


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2 HIGH-LEVEL DESCRIPTION

2.1 Functional Requirements

2.1.1 Overview The functional requirements are presented in the MFD Dual transfer mode [ 3].

The dual transfer mode feature has been introduced in 3GPP standard in order to simplify the internal architecture of the MSs and offer services that demand the simultaneous existence of a CS connection and a PS session. Contrary to classical Class A MSs, Class A DTM MSs do not need two independent transmitter/receiver chains to support simultaneous packet and circuit traffic.

Operators have expressed their need for Class A DTM MSs, since they want to offer services that demand the simultaneous existence of CS and PS connections. For instance, with DTM MSs, end-users can exchange their pictures during a voice call.

This is particularly important during the co-existence of GSM/GPRS with UMTS. Indeed, in the coming years, UMTS coverage may not be available in some areas where there is GSM/GPRS. As radio coverage is a vital service, in order for an operator to be able to sell "UMTS class A services", it is necessary to be able to imitate class A services in areas of only GSM coverage. On the other hand, the provision of class A services with GERAN technology is also essential for operators without UMTS coverage.

2.1.2 Activation of the feature The DTM feature is optional. It shall be activated at cell level only if it has been bought by the Customer.

2.1.3 Support of Gs interface Since release B7, Alcatel has not implemented paging co-ordination in the BSS and has instead promoted the support of the Gs interface. The Gs interface is then a pre-requisite to fully support the DTM feature. However, the BSS shall not forbid the activation of the DTM feature if the Gs interface is not supported (i.e. when the network mode of operation is set to NMO II or NMO III).

Alcatel implementation of the dual transfer mode feature assumes that the Core network supports the Gs interface. Thus, Alcatel Core network should also support the Gs interface.

2.1.4 Half rate Support of half rate configurations (one single timeslot encompassing one half rate circuit channel + one half rate packet channel) is not required in a first implementation of DTM.

When a MS operates in DTM, there is no requirement on channel rate, i.e. Full Rate or Half Rate. If the TCH of the DTM call is allocated in Half Rate, it is not required to allocate another Half Rate non-DTM call in the same timeslot. Moreover, it is not required to pile up TCH/H of two DTM calls.

2.1.5 EGPRS DTM has to be supported for both GPRS and EGPRS. As most of the DTM MSs should support EGPRS in the coming years, the handling of DTM MS supporting only GPRS should be as simple as possible.

2.1.6 Inter-cell handovers The number of inter-cell handovers should be minimized for DTM calls, as an inter-cell HO leads to the re-allocation of the packet session. Therefore, handover causes having a low priority should be inhibited for the time the MS is operating in DTM. Inter-Rat handovers towards 3G shall not be disabled for DTM calls.


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2.1.7 Intra-cell handovers The number of intra-cell handovers should be minimized for DTM calls, as an intra-cell HO leads to the re-allocation of the packet session. Therefore, handover causes having a low priority should be inhibited for the time the MS is operating in DTM.

2.1.8 Hierarchical networks As (E)GPRS are preferentially offered in macro cells, the BSS shall ensure that at least one PDCH can be used in micro cells to re-direct the MS towards the macro cells. It means that the BSS shall allow a PDCH used by a MS operating in DTM mode to be shared by other (E)GPRS MS. Indeed, as there are usually scarce PS resources in micro cell, the system shall allow packet access to several (including MS in DTM) at the same time.

2.1.9 Extended cells As usage of DTM in extended cells would give too many constraints on resource allocation, and also as handovers between inner and outer cells would lead to PS session break and restart, it is not required to support DTM in extended cells.

2.1.10 Support of GPRS QoS Interactions between DTM and GPRS QoS shall be managed as follows : Any PFC related to a MS in DTM or in dedicated mode shall be downgraded to best effort. TBFs with NRT PFCs are handled in the same way as best effort TBFs.

2.2 Overall description of the proposed solutions The dual transfer mode feature impacts the MS, the BSS, and the MSC. As far as the BSS is concerned, the BSS shall be able to: Serve a PS request and continue the on-going CS connection (i.e. when the MS is in dedicated mode). Serve a CS request and continue the on-going PS connection (i.e. when the MS is in packet transfer

mode). In this case, the PS service is interrupted during the establishment of the CS connection.

The A interface has been modified by the 3GPP standard to support the dual transfer mode so that the BSC knows the IMSI associated with each SCCP connection to the MSC. This procedure also applies to non-DTM MSs. This means that the BSC is able to ensure that PS paging messages can be delivered to MSs which have a CS connection to the MSC.

In order to minimize the impacts on MS implementation, the 3GPP standard has re-used the multislot class concept for dual transfer mode so that the possible timeslot configurations are such that: The number of radio timeslots allocated to a CS connection is limited to one. The TCH/PDCH radio timeslots allocated in each direction are contiguous and shall be allocated taking

into account the multislot class supported by the MS. Figure 1 shows an example of a multislot configuration (2 uplink, 3 downlink).

0 1 2 3 4 5 6 7Rx

Tx

f1

f2

0 1 2 3 4 5 6 7 0 1 2

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 75 6 7

CS PS Measurements

Figure 1: Example of multislot configuration of a GPRS class A mobile station in dual transfer mode.


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If GPRS signalling needs to be sent while the MS is in dedicated mode, the signalling LLC frames can be sent on the main DCCH (FACCH or SDCCH) with layer 2 SAPI 0. This procedure uses a new protocol called GPRS Transparent Transport Protocol (GTTP).

For paging, the behavior of the MS is as in class B mode of operation: the PCH takes priority to PPCH, and both to CBCH (see note). The MS shall not be required to operate in two different frequencies in the same moment in time. However, GSM CS and GSM PS services will be still supported simultaneously. Thus, the dual transfer mode feature is a subset of the GPRS class A capabilities.

Note : In case the mode of network operation is defined such that the network performs the paging for circuit-switched and packet-switched services on different paging channels, an class B UE in both idle mode and packet idle mode should either attempt to listen to both paging channels with priority for the circuit-switched service. The least priority shall go to listening of CBCH. See 3GPP TS 22.060 for further information.

2.3 Compliance to the marketing requirements This section identifies the compliance of the dual transfer mode feature to the marketing requirements.

Feature Item Compliance Comments

2.4 Compliance to 3GPP standard This section describes the compliance of the proposed Alcatel solution to the 3GPP standard (See Annex A for further details on 3GPP standard options. It especially highlights the options offered by the standard and which of them are implemented in Alcatel BSS.

3GPP functions B10 Comments Singleslot DTM operation Multislot DTM operation X (2+2), (3+2) and (2+3) configuration are

supported. (2+3) configuration requires Extended Dynamic Allocation (see ref[ 5]).

(E)GPRS DTM Multi Slot Class X Extended (E)GPRS DTM Multi Slot Class Handled as an (E)GPRS DTM Multi Slot Class Exclusive use of PDCH/H TCH/F + PDCH/F configuration X TCH/H + PDCH/H configuration Only allowed on the timeslot allocated to CS traffic TCH/H + PDCH/H + PDCH/F configuration Only possible in downlink direction Incremental support for Extended (E)GPRS Multi Slot Class

X But, configurations of using PDCH/H are not supported

Compliance to 3GPP release 1999 X Compliance to 3GPP release 4 X Dual Transfer Mode information field in the Old BSS to New BSS information IE in BSSAP Handover Required message

X This field is optional for the BSS.

CS paging co-ordination in NMO I X CS paging co-ordination in NMO II CS paging co-ordination in NMO III PS paging co-ordination X In any NMO RA capability update X Function already implemented in the BSS. Compliance to 3GPP release 6 X This does not include optional DTM enhancements


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in release 6. DTM Enhancements in release 6 DTM GPRS High Multi Slot Class Note: X means that the function is implemented in release B10, whereas means that the function is not implemented.

Table 1: Compliance to 3GPP standard.

2.5 Working assumptions The following assumptions have been made in this document: Single slot operation DTM MSs are not supported in Alcatel BSS because the implementation of these

MSs is difficult compared to the throughput expected in PS services. Only multislot operation DTM MSs are supported.

In Alcatels implementation, the Gs interface is required to support DTM to ensure CS paging co-ordination. It avoids the BSS to ensure the paging co-ordination. This choice is in line with Alcatel strategy which promotes the support of Gs interface. Furthermore, this assumption is consistent with the fact that paging co-ordination for GPRS is not ensured today when the network mode of operation is set to NMO II and NMO III where the Gs interface is absent. Indeed, in NMO II and NMO III, the MS cannot received CS paging while in packet transfer mode.

While in dual transfer mode, the BSS only allocates full rate PDCHs to the MS. The use of half rate PDCH is mainly interesting in single slot operation. In multislot operation, the use of half rate PDCH is only allowed on the timeslot allocated for the half rate TCH, and goes against the GPRS principles since a half rate PDCH cannot be shared with several mobile stations.

The dynamic Abis feature allows to simplify the radio resource allocations. It avoids to define new TBF re-allocation triggers. In this SFD, it is then assumed that the dynamic Abis feature is implemented.

2.6 Dependencies In this section, the technical dependencies between the dual transfer mode feature and with features addressed by other SFDs or already implemented are identified.

The dual transfer mode feature: requires the following features: Feature Dependency RAE-4 The RAE-4 feature allows the MFS to get a full picture of the

radio resources that can be used as PDCH. It simplifies the radio resource co-ordination required for the DTM feature.

is enhanced by the following features: Feature Dependency Dynamic Abis The dynamic Abis allows simplifing radio resource allocations. If

not implemented, new TBF re-allocations triggers may need to be defined to associate the required number of Abis nibbles to the PDCHs used by MSs operating in DTM.

USF granularity of 4 The use of the USF granularity of 4 may allow simplifying the radio resource allocation algorithms.

Extended Dynamic Allocation EDA allows to support DTM timeslot configurations with more than one PDCH in UL, see [ 5]

is incompatible with the following features: Feature Dependency

will be enhanced by the following future features:


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Feature Dependency 3GPP Rel. 6 DTM Enhancements

This 3GPP feature would allow to continue PS session, even when CS part is released. Note that this is optional both for MS and BSS.

3GPP DTM options that are not supported

See Section 2.4

decreases the interest of the following features: Feature Dependency

2.7 HW Coverage This section defines the HW coverage of the feature(s).

System: GSM 900 Yes DCS 1800 / DCS1900 Yes GSM 850 Yes

Network element: In the following tables, indicate : Xsw if feature supported by the NE with software impact, Xhw if feature supported by the NE with hardware impact Xsw+hw if feature supported by the NE with software and hardware impact. X : The feature is supported on the NE without hardware or software impacts. - : The feature is not supported by the NE or the NE is not concerned by the feature

Impact BTS Generation: BTS G2 with DRFU

(frozen at B7.2 level)

BTS Mk2 with DRFU (frozen at B7.2 level)

A9100 (Evolium standard) Xsw A9110 (M4M) Xsw A9110-E (M5M) Xsw

BSC Generation: BSC G2 Xsw BSC Mx Xsw

MFS: MFS Xsw

MFS Mx Xsw

Transmission: Alcatel TSC

Transcoder: TRAU G2 with DT16 TRAU G2 with MT120 TRAU G2.5 (with MT120)

MSC: MSC Xsw

SGSN: SGSN

Data IWF: Data IWF


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HLR: HLR

O&M: OMC-R Xsw POLO Xsw OEF Xsw LASER MPM/NPA Xsw RNO Xsw

MSTS: MSTS Xsw

2.8 Decision criteria In this section, the criteria relevant for deciding whether or not to implement the feature(s) are provided.

2.8.1 Standardisation The dual transfer mode feature has been defined first in release 1999. In 3GPP standard, operators like Vodafone have expressed their strong interest for DTM capable MSs.

2.8.2 Competition It is likely that our competitors like Ericsson and Nokia (Vodafones suppliers) will implement the dual transfer mode feature in the coming years.

From the MS suppliers point of view, here is the status as known by Alcatel : Nokia : DTM with class 9 &11 and 3G hand over : Available now

Philips : DTM with class 9 &11 : Q1'06

2.8.3 Customer T-Mobil requires this feature for quite a long time

2.8.4 Gains This section qualifies and quantifies the gains brought by the feature. 2.8.4.1 Telecom gains The dual transfer mode feature does not bring any Telecom gain. 2.8.4.2 Operational gains None.

2.8.5 Risks The following risks have been identified: The core network has to support the DTM feature especially the Common ID procedure. If not

supported, PS paging co-ordination cannot be ensured. The dual transfer mode has an high impact on existing signalling protocols, a great care shall then be

taken to ensure no regression at the B9 to B10 migration. The dual transfer mode feature will seriously impact BSC load. Impacts on the load of the processors of

the BSC needs to be assessed. The load on the BSCGP should be impacted due to the additional messages used during paging and

assignments. The BSCGP load needs to be assessed. The IMSI of the DTM MS is stored in the BSC MS contexts, which may make appear memory limitations

of the BSC.


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DTM will lead to a more complex resource allocation algorithm


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3 SYSTEM IMPACTS

3.1 Telecom

3.1.1 Functional-level description This section describes the functional impacts of the dual transfer mode feature. Each main function of the BSS is analysed separately to show the impacts. 3.1.1.1 (De)activation of the dual transfer mode feature The O&M parameter called EN_DTM allows the activation of the dual transfer mode feature at cell level. This parameter is provided only to the BSC. It is sent to the MFS through BSCGP interface. DTM is not supported in following types of cells :

Non-Evolium BTS Extended cells Cells where MAX_PDCH_HIGH_LOAD < 2 ((E)GPRS is mandatory for DTM operation, and at least

2 PDCHs are required in the PS zone for allocation of DTM resources to (at least) one DTM call) Note that the feature cell shared over two BTSs does not allow sharing a cell between one Evolium BTS and one non-Evolium BTS.

3.1.1.2 Broadcast of (packet) system information 1) Overview A DTM MS is aware that the dual transfer mode of operation is supported in the cell by the DTM_SUPPORT bit sent in the following (packet) system information messages (See also Table 2): In System Information Type 13 message (sent on BCCH) when no PBCCH is present in the cell, In Packet System Information Type 1 message (sent on PBCCH or on PACCH) when a PBCCH is

present in the cell. In System Information Type 6 message (sent on SACCH) when the MS is in dedicated mode or in dual

transfer mode. No distinction is done between DTM capable MS and DTM non-capable MS (the DTM support is always indicated).

In DTM Information message (sent on FACCH) when the MS is in dedicated mode in order to reduce the interruption of GPRS services. This message is only sent to DTM capable MS. It allows informing the MS that the DTM is supported in the serving cell after a handover so that the MS does not need to wait for the receipt of the System Information Type 6 message before initiating the GPRS access in the new cell. For instance, if the serving cell broadcasts SI5, SI5bis, and SI6 messages on SACCH, the minimum scheduling period of SI6 is about 0.5 * 3 = 1.5 s. A gain of up to 1.5 s is then expected in the GPRS interruption time during the handover procedure.

In Packet System Information Type 13 message (sent on PACCH) when the MS is in packet transfer mode.

In Packet System Information Type 14 message (sent on PACCH) when the MS is in dual transfer mode.

The DTM_SUPPORT bit is set in the (packet) system information messages only if the flag EN_DTM is enabled.

Messages Channels State of the MS when receiving the message System Information Type 13 BCCH Packet idle mode Packet System Information Type 1 PBCCH

or PACCH

Packet idle mode or Packet transfer mode

System Information Type 6 SACCH Dedicated mode Dual transfer mode

DTM Information FACCH Dedicated mode Packet System Information Type 13 PACCH Packet transfer mode


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Packet System Information Type 14 PACCH Dual transfer mode

Table 2: Messages indicating to the MS the DTM support in the cell.

2) Broadcast of the PSI14 message The PSI14 message allows MS operating in DTM to reduce the interruption of a GPRS session after a CS connection release. Indeed, the MS may use the PSI14 as a substitute for the SI13 message after the release of the CS connection until the MS receives the SI13 message or starts receiving information on PBCCH. A gain of up to 1.8 s (corresponding to the minimum period to send the SI13 message on BCCH) can then be expected in the interruption time of GPRS sessions.

The Packet System Information Type 14 message is sent periodically (with a period set by the parameter T_PSI_PACCH) on the PDCHs that carry the PACCH of at least one DTM TBF. A DTM TBF is a TBF established for a MS operating in dual transfer mode. As a simplification, PSI14 is sent on all PACCHs of a DTM enabled cell, so that MAC does not need to know whether a TBF is DTM or not.

Support of DTM PSI13 PSI14 If DTM is enabled in the cell X X If DTM is disabled in the cell X

(a) in a cell without a PBCCH

Support of DTM PSI1 PSI14 If DTM is enabled in the cell X X If DTM is disabled in the cell X

(b) in a cell with a PBCCH Table 3: Packet system information messages periodically sent to the MS on a given PDCH.

When both the PSI13 and PSI14 messages or both the PSI1 and PSI14 messages are periodically sent on a PDCH, MAC layer ensures that the time difference between two consecutive messages is T_PSI_PACCH/2.

3.1.1.3 Monitoring the RR operating of the MS In addition to the existing states, the MFS and the BSC shall manage the new state: dual transfer mode (See also Section 9.4).

The MFS and the BSC considers that a DTM MS has entered the dual transfer mode when the packet request procedure initiated in dedicated mode is completed, i.e.: For the BSC : At receipt of the 44.018 Assignment Complete message in response to a DTM

Assignment Command message, or at the sending of a 44.018 Packet Assignment message. For the MFS : when the TBF is successfully established, further to a command for DTM assignment sent

to the BSC

Similarly, the MFS and the BSC considers that a DTM MS has left the dual transfer mode when either the CS connection is released or the PS connection is released, i.e.: At the sending of the 44.018 Channel Release message, or At the end of the DL TBF if there was no UL TBF on-going, i.e. at the receipt of the final Packet Downlink

Ack/Nack message (in RLC acknowledged mode) or of the final Packet Control Acknowledgement message (in RLC unacknowledged mode).

At the end of the UL TBF if there was no DL TBF on-going, i.e. at the receipt of the final Packet Control Acknowledgment message in response to the final Packet UL Ack/Nack message.

At the detection by RLC of abnormal TBF release 3.1.1.4 Paging co-ordination in the BSS When the DTM feature is enabled, the BSS shall use the following channels to page a DTM MS engaged in a CS or PS connection (See also Table 4 for NMO I): The PACCH to page a DTM mobile for a CS connection if this mobile has already a PS connection on-

going. In this case, the MS is in packet transfer mode.


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The main DCCH (FACCH or SDCCH) to page a DTM mobile for a PS connection if this mobile has already a CS connection on-going. In this case, the MS is in dedicated mode.

This can be achieved only if there is a paging co-ordination between the PS and CS domains. Each time the BSC receives an incoming CS paging for a DTM MS it needs to know if this mobile has already a PS connection on-going so that it is paged on the PACCH. Conversely, each time the MFS receives an incoming PS paging for a DTM MS it needs to know if this mobile has already a CS connection on-going so that it is paged on the main DCCH (FACCH or SDCCH). It is the reason why the support of paging co-ordination is necessary for the DTM feature.

State of a GPRS-attached DTM mobile station

CS paging (*) PS paging

In packet idle mode PCH if no PCCCH PPCH if PCCCH

PCH if no PCCCH PPCH if PCCCH

In packet transfer mode PACCH (**) NA In dedicated mode NA Main DCCH (***) In dual transfer mode NA NA Note (*): CS paging of GPRS-attached MS shall go via the SGSN in NMO I. Note (**): The paging co-ordination is ensured by the SGSN. Note (***): The paging co-ordination shall be ensured by the BSS. The BSS shall send a packet notification if the DTM MS is in GMM Standby state and dedicated mode. If the DTM MS is in GMM Ready state and dedicated mode it will receive from the SGSN a DL LLC PDU which will initiate a packet downlink assignment with the DTM Assignment Command or Packet Assignment message. Table 4: Paging channel used depending on the state of the MS. Network operation mode I is assumed.

1) CS paging co-ordination: DTM MS in packet transfer mode upon receipt of a CS paging If the network operates in NMO II or NMO III, there is no Gs interface between the MSC and the SGSN. In this case the paging co-ordination could be done by the BSS. The BSC needs to know the list of mobiles engaged in PS connection and the MFS needs to know the list of mobiles engaged in CS connection. The co-ordination between the MFS and the BSC to know on which channel to page the DTM mobiles could be achieved thanks to information contained in an IMSI data base located either in the MFS or the BSC. If the network operates in NMO I, i.e. there is a Gs interface between the MSC and the SGSN, the paging co-ordination is done by the network (between the MSC and the SGSN). In this case the SGSN sends CS and PS paging messages to the MFS on the Gb interface. In this case the co-ordination between the MFS and the BSC is still needed but only the MFS needs to know the list of DTM MSs engaged in a CS connection. Moreover, the BSC does not need to know the list of mobiles engaged in a PS connection.

It is proposed that the BSS ensures the CS paging co-ordination only in NMO I when the Gs interface is present. This choice is explained by the following justifications: In release B9, in NMO II and III, the paging co-ordination is not ensured for CS paging messages

received while the MS is in packet transfer mode. It is not required that the DTM feature improves the paging management here.

According to the information received from P&S, it is likely that most of the operators will use the Gs interface in the coming years.

If the paging co-ordination were required in NMO II and III, upon receipt of each CS paging the BSC will have to check whether the MS is in packet transfer mode. The BSC will then have to maintain a list of MSs in PTM, which will increase BSCGP load (due to the exchange of the identity of the MS in PTM at the beginning of the PTM and at the end of the PTM).

As the BSS does not support CS paging co-ordination, the flag BSS_PAGING_COORDINATION included in the GPRS Cell Options IE of SI13, PSI1, PSI13 and PSI14 shall be set to 0: The cell does not support CS paging coordination (See [ 10] and [ 11]]).


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2) PS paging co-ordination: DTM MS in dedicated mode upon receipt of a PS paging The MFS has to know whether or not a DTM MS is in dedicated mode in order to possibly initiate a mobile terminating PS session on the main DCCH. For that purpose, the MFS shall handle a specific context for each DTM MS in dedicated mode.

A new BSCGP message is then introduced to let the BSC provide the MFS with the IMSI of the DTM MS in dedicated mode. This message is called BSC Shared DTM Info Indication. In order to ensure the PS paging co-ordination for DTM MS in dedicated mode, this message shall be sent to the MFS: At regular intervals (monitored by the timer T_SHARED_DTM_INFO (BSC)), to avoid any

desynchronisation between BSC and MFS, as soon and as long as the MS enters dedicated mode At CS call establishment: As soon as the BSC retrieves the IMSI of the DTM MS (when establishing the

SCCP connection), it shall send it to the MFS through a BSC Shared DTM Info Indication message. At CS call release: Once the CS call is released, the BSC shall send the BSC Shared DTM Info

Indication message indicating that the MS has left the dedicated mode. At completion of any procedure modifying the dedicated channel allocated to the MS (immediate

assignment, normal assignment, intracell handover, intercell handover, DTM assignment, CS release)

Additionally, whenever the MS leaves DTM mode following the release of all its TBFs, the MFS sends to the BSC the message MFS Shared DTM Info Indication, to re-enable all HO causes (see sections 2.1.6 and 2.1.7). This message is acknowledged by the BSC through the message MFS Shared DTM Info Indication ACK.

As the BSC identifies the MS context with the BSC reference (BSSAP_REF plus DTC_id) and the MFS identifies the MS context with the IMSI, both the BSC reference and the IMSI are required to identify a given DTM MS on the BSCGP interface. That means that the BSC Shared DTM Info Indication message contains both the IMSI of the MS and the corresponding BSC reference id.

3.1.1.5 MS contexts shared between the MFS and the BSC The BSS manages two MS contexts for a MS operating in dual transfer mode: One MS context is located in the BSC and maintain information elements related to CS domain, One MS context is located in the MFS and maintain information elements related to PS domain.

As explained in Section 3.1.1.4, the MFS shall be informed that a DTM MS has entered or left the dedicated mode to allow the MFS to forward PS paging or packet downlink assignment messages to the BSC which will then send them on the main DCCH. This exchange of information between the two MS contexts is done through the BSC Shared DTM Info Indication message.

In order to allow to share Information elements between these two contexts, the MS contexts shall be identified by two MS identifiers, the BSC reference (BSSAP_REF plus DTC_id) derived from the SCCP id and the MS IMSI. The IMSI is provided to the BSC during: CS connection establishments for normal assignments, i.e. at CS call establishment, CS connection establishments for external handovers PS connection establishments CS connection establishments on SDCCH only

The IMSI is provided to the MFS during : PS connection establishments

The SCCP id is provided to the BSC during: CS connection establishments for normal assignments, i.e. at CS call establishment, CS connection establishments for external handovers.

1) CS connection establishments for normal assignments The 3GPP standard has defined the Common ID procedure to inform the BSC about the IMSI of the MSs (for both non-DTM or DTM MSs) at call establishments. The BSC shall then be able:


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To retrieve the IMSI of a MS at CS call establishment on receipt of the Common ID message over the SCCP connection or in the SCCP Connection Confirm message.

To associate the MS with the RR and SCCP connections for the duration of the RR connection.

It can be noticed that the Common ID procedure is required for two purposes: To ensure PS paging co-ordination: The IMSI has to be known by the MFS during the dedicated mode to

retrieve the CS connection concerned by the PS paging (See the scenario described in Figure 15). To ensure CS paging co-ordination: The IMSI has to be known by the BSC to retrieve the MS context in

the MFS and let the MFS launch the re-establishment of the DL TBF interrupted due to the CS paging (See the scenario described in Figure 18).

2) CS connection establishments for external handovers The BSC shall be able: To retrieve the IMSI included in the 48.008 Handover Request message. To associate the IMSI of the MS with the corresponding RR connections. The MSC shall include the IMSI of the MS in the 48.008 Handover Request message at least when the MS is dual transfer mode capable and the IMSI is available.

This scenario is described in Figure 23. 3) PS connection establishments In downlink, the MFS receives the IMSI of the MS: In the PS PAGING BSSGP PDUs if the MS is in GMM Standby state In the DL LLC PDUs if the MS is in GMM Ready state. As an exception, the SGSN may omit the IMSI in

the DL LLC PDU if the MS identified by the TLLI is in MM non-DRX mode period (i.e. during a GMM procedure for GPRS attach or routing area updating) and the SGSN does not have a valid IMSI.

In uplink, the MFS cannot retrieve the IMSI from the UL TBF. Only the TLLI is used as MS identifier for UL TBFs. Usually, except in case of cell updates, if the MS enters the packet transfer mode through an UL TBF, the IMSI is known on receipt of the next DL LLC PDU. Therefore, it seems acceptable not to use the RA capability update procedure to retrieve more quickly the IMSI of the MS. The consequence is that during a cell update without DL TBF establishment, the MS doesnt monitor the (P)CCCH and then may miss CS paging messages received on the Gs interface and sent on (P)CCCH. Note that this problem also exists in release B9.

4) Defense mechanism As explained above, periodic sending of BSC Shared DTM Info Indication message is implemented as defense mechanism between the MFS and the BSC to avoid inconsistent information stored either in the BSC or in the MFS, e.g. keeping in the MFS a MS marked as in "dedicated mode" while this MS has left the "dedicated mode".

3.1.1.6 Radio resource management 3.1.1.6.1 Supported DTM multislot classes As the implementation of DTM single slot operation is difficult for the MS, it is likely that in the coming years only multislot operation DTM MS will be available. Therefore, only multislot operation is supported by Alcatel BSS.

For multislot operation, the 3GPP standard allows mixing full and half rate PDCH in the downlink direction. But, the 3GPP standard forbids this mix in the uplink direction. In order to simplify the first Alcatel DTM implementation, it is proposed not to support such mix configurations. Therefore, only full rate PDCHs will be supported and Extended (E)GPRS DTM MS will be handled as normal (E)GPRS DTM MS in Alcatel BSS (See Section 9.1.1 for the definition of Extended (E)GPRS DTM MS).

The configurations supported by Alcatel BSS are indicated in Table 5. For instance, a 3+2 configuration has to be interpreted as a configuration where One TCH and two PDCHs are allocated to the MS in DL, One TCH and one PDCH are allocated to the MS in UL.


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The possible timeslot configurations are shown in Figure 1 for (2+2) and in Figure 2 for (3+2). Note that the asymmetric configuration (2+3) is supported for MS multislot Class 11 allow with Extended Dynamic Allocation since the USF mechanism does not allow that the number of PDCHs assigned in UL is higher than the number of PDCHs assigned in DL, see ref.[ 5] for details. Whenever the multislot class indicated by the MS is not supported by Alcatel BSS, the BSS will look for an allocation based on a multislot class compatible with the MS multislot class and supported by Alcatel BSS (see section 9.1.1).

Multislot class

Type Rx Tx Sum Ttb Tra Trb Symmetric configuration

Asymmetric configuration

5 1 2 2 4 1 3 1 (2+2) NA 6 1 3 2 4 1 3 1 (2+2) NA 9 1 3 2 5 1 2 1 (2+2) (3+2) 10 1 4 2 5 1 2 1 (2+2) (3+2) 11 1 4 3 5 1 2 1 (2+2) (3+2), (2+3) in EDA

Table 5: DTM multislot classes supported in Alcatel BSS.

TP

210

T

543 76

210 543 76

DL (Rx)

UL (Tx) P (a)

PT

210

P

543 76

210 543 76

DL (Rx)

UL (Tx) T (b)

Legend: T: TCH, P: PDCH, Bold underlined timeslots represent the PACCH location. Figure 1: Supported (2+2) timeslot configurations

PTP

210

PT

543 76

210 543 76

DL (Rx)

UL (Tx) (a)


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TPP

210

TP

543 76

210 543 76

DL (Rx)

UL (Tx) (b)

Legend: T: TCH, P: PDCH, Bold underlined timeslots represent the PACCH location. Figure 2: Supported (3+2) timeslot configurations.

3.1.1.6.2 CS call multiplexing on TCH The 3GPP standard allows the following configurations: Sharing a radio timeslot for two DTM CS calls as illustrated in Figure 3 b), Sharing a radio timeslot for one DTM CS call and one non-DTM CS call as illustrated in Figure 3 a). It is proposed not to implement these options for the following reasons: Sharing a radio timeslot for one DTM CS call and one non-DTM CS call may lead to create a hole in the

PDCHs allocated to the MFS especially if the DTM CS call is released a long time before the release of the non-DTM CS call. Note that intracell handovers to re-assign a TCH in the zone preferred for CS allocations are not supported.

Sharing a radio timeslot for two DTM CS calls may be interesting in case the cell is high loaded. However, as the penetration rate of DTM MS should be low in release B10, this case does not need to be optimized in a first implementation of DTM.

These options increase the number of scenarios to be tested for a first implementation of the DTM feature.

Therefore, as a simplification, TCH for DTM will be exclusively established in FR, whatever the MSC request or the previous allocation.

T1P1P1

210

P1

543 76

210 543 76

DL (Rx)

UL (Tx)

T2

T1

T2

(a)

T1P1P1

210

P1

543 76

210 543 76

DL (Rx)

UL (Tx)

T2

T1

T2

P2P2

P2

(b)


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Legend: T1: HR TCH of MS 1 T2: HR TCH of MS 2 P1: FR PDCH of MS 1 P2: FR PDCH of MS 2 Bold underlined timeslots represent the PACCH location.

Figure 3: Examples of a TCH shared by two HR CS calls. 3.1.1.6.3 TBFs multiplexing on PDCHs The principles below could be followed when allocating the PDCHs to a MS in DTM: The MFS shall allow the multiplexing of TBFs on DTM PDCHs. A DTM PDCH is a PDCH used by a MS

operating in dual transfer mode. An example of such a multiplexing is shown in Figure 4. The MFS shall offer the best throughput to a DTM MS taking into account the QoS requirements of the

other MSs and the EGPRS capability of the MS. The radio timeslots to serve a DTM request (including the TCH) are searched assuming that every radio

timeslot offers the same voice link quality (i.e. to select a TCH the MFS will not take into account the interference level of each radio timeslot provided by the BTS to the BSC).

As the penetration of non-EGPRS capable DTM MS should be very low, no complex behaviour is required to handle allocations for non-EGPRS capable MSs operating in DTM even if it leads sometimes to non-optimal allocations.

Note that the term throughput refers to a throughput measured in radio transmission units. It is fully independent of the radio conditions of the PS connection. As the MFS is the master to find the best radio resources to be allocated to DTM MSs (including TCH), then radio link quality will not be considered.

P1

210 543 76

210 543 76

DL (Rx)

UL (Tx)

T1

T1

P2

P1

P2P2

P2

MS1 is is a multislot class 5 MS2 is is a multislot class 9

Legend: T1: FR TCH of MS 1 P1: FR PDCH of MS 1 P2: FR PDCH of MS 2 Bold underlined timeslots represent the PACCH location.

Figure 4: Examples of a DTM PDCH shared by several MSs.

3.1.1.6.4 Maximizing the number of consecutive PDCHs The MSs operating in DTM will generate holes in the allocation zone where the priority is given to PS traffic. Indeed, the TCHs allocated to MSs in DTM reduce the multiplexing gain offered when the whole available PDCHs are consecutive on a given TRX. The following assumptions are proposed for DTM allocation:

As a DTM TBF cannot be completely preempted, it is proposed to find resources for such a call in the non preemptable PS zone. This means that the allocation of a DTM call is limited to the MAX_SPDCH_HIGH_LOAD zone (see [ 17] for the definition of this zone). Additionally, the DTM TBF is allocated in the leftmost part of the packet zone, in order to preserve CS capacity.

DTM best effort TBFs and best effort (BE) TBFs are considered with the same priority (same weight, same scheduling). More bandwidth is not offered to a DTM BE TBF compared to a BE TBF.

Specific constraints apply for PS resources to be allocated in DTM :


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The PDCH shall be allocated in the MFS (i.e. the PDCH is in allocated state, but not in the not allocated or de-allocating state).

The PDCH shall be located in the non preemptable PS zone of the cell The PDCH shall not be in the Full state in the considered direction The PDCH shall not be locked due to a CS preemption process

Specific constraints apply for CS resources to be allocated in DTM : The RTS shall be allocated in the MFS (i.e. the PDCH is in allocated state, but not in the not

allocated or de-allocating state). The RTS shall be located in the non preemptable PS zone of the cell The RTS position shall be compatible with the DTM multislot class of the MS The RTS does not support any RT PFC The RTS does not support any PACCH channel (when considering all the DL and UL TBFs

established on this RTS and all the RT PFCs created on this RTS). The basic Abis nibble mapped onto the RTS is available, i.e. it is either free or it is used in an M-

EGCH link from which it is possible to release one GCH.

3.1.1.6.5 Sharing of the radio resources between the BSC and the MFS It is proposed that the MFS is the master to find the best radio resources to be allo

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Dual Transfer Mode b 10