NED (3)

GSM/EDGE BSS, Rel. RG20(BSS), Operating Documentation, Issue 07

BSC/TCSM description

PCU2 in BSC

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Issue 3-1Approval Date 2011-04-07

Confidential

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Id:0900d8058084ea0dConfidential

The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. This documentation is intended for the use of Nokia Siemens Networks customers only for the purposes of the agreement under which the document is submitted, and no part of it may be used, reproduced, modified or transmitted in any form or means without the prior written permission of Nokia Siemens Networks. The documentation has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Nokia Siemens Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation.

The information or statements given in this documentation concerning the suitability, capacity, or performance of the mentioned hardware or software products are given "as is" and all liability arising in connection with such hardware or software products shall be defined conclusively and finally in a separate agreement between Nokia Siemens Networks and the customer. However, Nokia Siemens Networks has made all reasonable efforts to ensure that the instructions contained in the document are adequate and free of material errors and omissions. Nokia Siemens Networks will, if deemed necessary by Nokia Siemens Networks, explain issues which may not be covered by the document.

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Other product names mentioned in this document may be trademarks of their respective owners, and they are mentioned for identification purposes only.

Copyright © Nokia Siemens Networks 2011. All rights reserved

f Important Notice on Product SafetyThis product may present safety risks due to laser, electricity, heat, and other sources of danger.

Only trained and qualified personnel may install, operate, maintain or otherwise handle this product and only after having carefully read the safety information applicable to this product.

The safety information is provided in the Safety Information section in the “Legal, Safety and Environmental Information” part of this document or documentation set.

The same text in German:

f Wichtiger Hinweis zur Produktsicherheit Von diesem Produkt können Gefahren durch Laser, Elektrizität, Hitzeentwicklung oder andere Gefahrenquellen ausgehen.

Installation, Betrieb, Wartung und sonstige Handhabung des Produktes darf nur durch geschultes und qualifiziertes Personal unter Beachtung der anwendbaren Sicherheits-anforderungen erfolgen.

Die Sicherheitsanforderungen finden Sie unter „Sicherheitshinweise“ im Teil „Legal, Safety and Environmental Information“ dieses Dokuments oder dieses Dokumentations-satzes.

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Table of contentsThis document has 35 pages.

Summary of Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1 Overview of PCU2 in BSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2 PCU2 plug-in unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.1 PCU2 plug-in unit variants and hardware architecture . . . . . . . . . . . . . 102.2 PCU2 software architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.3 Implementing PCU2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3 Network configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4 Operability of PCU2 in BSC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.1 Hardware and software configuration management . . . . . . . . . . . . . . . 174.2 Operator parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.3 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

5 Key performance indicators and counters for PCU2 . . . . . . . . . . . . . . . 305.1 Benchmarking KPIs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305.2 Counter differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.3 Indirect effects of other implementation differences in counters . . . . . . 34

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List of figuresFigure 1 Main hardware blocks in the PCU1 and PCU2 variants . . . . . . . . . . . . . 10Figure 2 Restructured task management in PCU2 . . . . . . . . . . . . . . . . . . . . . . . . 11

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List of tablesTable 1 PCU plug-in unit variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Table 2 PCU2 software image names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Table 3 PRFILE parameter differences between PCU1 and PCU2 . . . . . . . . . . 18Table 4 Extended uplink TBF scheduling rate . . . . . . . . . . . . . . . . . . . . . . . . . . 25Table 5 Delayed downlink TBF polling rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

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PCU2 in BSC Summary of Changes

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Summary of ChangesChanges between document issues are cumulative. Therefore, the latest document issue contains all changes made to previous issues.

Changes between issues 3-1 and 3-0New PCU plug-in unit variant is added in the table, PCU plug-in unit variants.

Changes between issues 3-0 and 2-1New SW modules are added in the table, PCU2 software image names.

Changes between issues 2-1 and 2-0Information on InSite BTS has been removed.

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Overview of PCU2 in BSC

1 Overview of PCU2 in BSCFor GPRS/EDGE, the BSC needs the packet control unit (PCU), which performs all the data processing tasks related to GPRS/EDGE traffic. It implements both the Gb and Ibis interfaces in the BSC, removes any unnecessary TRAU overheads coming from the Ibis interface, and forms the Frame Relay/IP frames for the Gb interface.

The PCU is a key unit in the following procedures:

• GPRS/EDGE radio resource allocation, management and scheduling • GPRS/EDGE radio connection establishment and management • GPRS/EDGE data transfer • Modulation and coding scheme selection • Gb uplink load sharing and downlink flow control • Collecting of PCU statistics

In the BSC, the PCU hardware plug-in units are configured to every BSC signalling unit (BCSU) and are activated based on the traffic needs.

PCUM is a new functional unit in multi controller. PCUM and PCU2-E (Packet Ibis) variants are same from SW point of view. For more information, see PCUM documen-tation.

The PCU plug-in unit family consists of the following plug-in unit variants:

Related topics

• BSC/TCSM Hardware Descriptions • Plug-in Unit Descriptions

• PCU2-D • PCU2-U • PCU2-E

General name

Name of hardware product variant

Explanation

PCU Packet Control Unit, a general term for all GSM/EDGE PCU versions

PCU1 PCU First generation PCU for BSc and BSC2i

PCU-S First generation PCU for BSc and BSC2i

PCU-T First generation PCU for BSc and BSC2i

PCU-B First generation PCU for BSC3i, includes two logical Plus

PCU2 PCU2-U Second generation PCU for BSc and BSC2i

PCU2-D Second generation PCU for BSC3i, includes two logical Plus

PCU2-E Second generation PCU for BSC3i and Flex BSC

PCUM Packet Control Unit in Multi controller BSC, it is a new functional unit in multi controller BSC.

Table 1 PCU plug-in unit variants

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PCU2 in BSC Overview of PCU2 in BSC

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• Plan and Dimension • Abis EDGE Dimensioning • BSC EDGE Dimensioning • Gb EDGE Dimensioning

• Activate • Data

• Activating and Testing BSS10083: EGPRS • Activating and Testing BSS9006: GPRS

• Reference • Commands

• Service Terminal Commands • PCU2 Service Terminal Commands

• Counters/Performance Indicators • EDGE, GPRS, and GSM Voice Key Performance Indicators

• Parameters • BSS Radio Network Parameter Dictionary • PRFILE and FIFILE Parameter List

• For more information on PCUM, see- PCUM documentation.

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PCU2 plug-in unit

2 PCU2 plug-in unitThe second generation packet control unit (PCU2) is a plug-in unit in the BSC. The PCU2 is an independent processing unit embedded in every BCSU of the BSC. It takes advantage of the BSC’s redundancy and overload protection mechanisms.

The embedded solution removes the need for additional network elements or units when introducing the GPRS/EDGE functionality in the network, consequently offering opera-tional efficiency.

The PCU2 solution is designed to offer support for the new service enablers and func-tionalities introduced in the GSM-based networks with GPRS/EDGE. The PCU2 hardware and software architecture creates a basis for these new packet data related functionalities,

2.1 PCU2 plug-in unit variants and hardware architectureIn the PCU2 solution, there are three PCU2 plug-in unit variants which implement the new hardware architecture. PCU2-D, which includes two logical PCU2 units is used for BSC3i, PCU2-U is used for the older BSC versions and PCU-E is used for BSC3i and FlexiBSC. For more information on the PCU2 plug-in unit variants, see the PCU2 hardware plug-in unit descriptions.

PCU2 introduces more processing capacity for both PowerQuicc (PQ) and digital signal processors (DSP) with external memory and hardware architecture enhancements to create a basis for new packet data related functionalities.

The functionalities include enhancements in the following areas:

• Enhanced processing capabilities for PQ and DSPs with external memory and a higher DSP-level Abis channel connectivity to fully support the software architecture enhancements.

• Enhanced processing capacity of PCU-E DSPs increases significantly the number of channels served by a single plug-in unit. It thus provides sufficient packet data capacity within the limited space and amount of BSCU units.

• Actual traffic and O&M information separated on different paths between PQ and DSPs.

Figure 1 Main hardware blocks in the PCU1 and PCU2 variants

PCU2-D/U

PQII

8 DSP Cores

Exte

rnalD

SP

Me

mo

ry

PCU1

PQII

16 DSP Cores

PCU2-E

PQIII

6 DSP Cores

Exte

rnalD

SP

Me

mo

ry

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PCU2 in BSC PCU2 plug-in unit


2.2 PCU2 software architectureThe PCU2 software architecture, with its modular decomposition and restructured task management, uses the hardware architecture changes to provide a basis for the new packet data related functionalities.

With PCU2, the DSPs take care of more tasks than in PCU1. The tasks include radio link control (RLC), scheduling, quality control, as well as Abis L1 processing. With PCU1, the DSPs only take care of the Abis L1 processing.

Figure 2 Restructured task management in PCU2

The PCU2’s software architecture introduces enhancements in the following areas:

• The RLC, Scheduler, and Quality control functionalities implemented on the DSPs improve the RTT and balances load between PQ and DSPs.

• The asynchronous data transfer of LLC PDUs, which is used instead of the synchro-nous transfer of RLC/MAC blocks between PQ and DSP, reduces the load in the PQ-DSP interface and provides faster PQ-DSP transactions.

• For PCU2-D/U, BTS support is increased from 64 to 128, and the TRX resource support is extended from 128 to 256. PCU2-E supports maximum of 384 BTS and 1024 TRXs. Thus there is increased BTS and TRX support, which consequently provides more flexibility to the segment concept used with Multi BCF Control and Common BCCH.

• The new GPRS link adaptation algorithm enables the support for the GPRS coding schemes 3 and 4 (CS-3 and CS-4). It also gives the possibility to reach a higher throughput per subscriber when the GPRS coding schemes 3 and 4 are used.

• The use of uplink state flag (USF) granularity 4 improves the use of the radio inter-face resources in a situation where the GPRS and EGPRS mobiles are in the same radio time-slot (RTSL).

• Improved end user service perception: The PCU2 software architecture implements RLC on DSPs and, depending on the radio conditions, gives benefit to application level delays, that is active and idle RTTs. The active RTT measures delay from the data transfer point of view has an impact for example on the duration of file down-loads experienced by the end users as well as on services with fast interaction requirements. The idle RTT measures delay from the access point of view, that is, the impact to TCP startup, improves on its part the end user experience for example in downloading web pages.

In the S15 software release, the PCU2 does not support the following:

PCU1

PQ

Resource ManagerGb InterfaceRLCScheduler

DSP

Abis L1

PCU2

PQ

Resource ManagerGb Interface

DSP

Abis L1RLCSchedulerQuality Control

Exte

rnalD

SP

Mem

ory

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PCU2 plug-in unit

• PBCCH/PCCCH

2.3 Implementing PCU2The PCU2s can be installed to any GSM/EDGE BSC. PCU2-D is used with BSC3i, PCU2-U with older BSC products and, PCU-E is used for BSC3i and Flexi BSC. In the PCU2 upgrade, the existing PCU1s are replaced with PCU2s. It is required to have at least BSC S11.5 software installed before the PCU2 hardware upgrade is performed. The PCU2 plug-in units cannot be created into the BSC hardware database before the software has been activated.

The preferred PCU2 configuration can be selected flexibly according to the functionality and packet switched traffic handling capacity needs. Mixed configurations with PCU1s are also supported, which enables flexible and on need based equipping of PCU2s.

The PCU2 hardware is installed by using a spare BCSU for the hardware upgrade and making BCSU switchovers until every unit is upgraded. The PCU2 hardware upgrade is done in the following way:

1. Change the BCSU working state from SP-EX to SE-NH.2. Switch the BCSU cartridge power off.3. Check that all the PCU2 plug-in unit jumpers are set according to the instructions.4. Install and configure the PCU2 to BCSU.5. Switch the BCSU cartridge power on.6. Change the BCSU state to TE-EX.7. Run the diagnostics.8. Once the diagnostics have been completed, change the BCSU working state to SP-

EX.9. Repeat the steps for all the BCSUs to be equipped with PCU2.

PCU2 is activated with a license key. In the BSC, the PCU licensing is linked to the current PCU configuration. The configuration can be defined according to the following alternatives and is always needed when you define the required PCU license type (PCU1 or PCU2):

• In configurations where only PCU1s are used in the same track position, a PCU1 license key is always required for the active PCU1s.

• In mixed configurations where PCU1s and PCU2-D/Us are used in the same track position, a PCU1 license key is always required for the active PCU1s and PCU2-D/Us. For example, when a TRX extension is done with PCU2-D/Us, BCSUs for a BSC configured with PCU1s, a PCU1 license key is also needed for the TRX exten-sion.

• In configurations where only PCU2-D/Us are used in the same track position, a PCU2 license key is always required for the active PCU2-D/Us. For example, in a PCU2-D/U hardware upgrade where all the existing PCU1s are replaced with PCU2-D/Us, a PCU2 license key is also needed.

• In configurations where PCU2-E is used, a PCU2 licence key is required but the only difference is that for activating each beginning step of 256 channels per PCU an additional PCU2 license key is required.

g For PCU2 to support Packet Abis, the license for BSS21440: Packet Abis over TDM/Ethernet should be activated.

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PCU2 in BSC PCU2 plug-in unit


For more detailed upgrade information, see Enabling GPRS in BSC in Activating and Testing BSS9006: GPRS under Activate/Packet Switched Data.

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Network configuration

3 Network configurationIn this section, the recommendations and dimensioning differences which you need to know when introducing PCU2 are discussed. For more information on EDGE dimen-sioning, see GSM/EDGE Dimensioning.

Pure GPRS network (CS1&CS2 only)The network is considered as pure GPRS network, when edge is disabled in all cells under the PCU. Edge is disabled when EGENA=N (with the MML command ZEQV).

In PCU1, it is possible to have some EDAPs which do not have any TRXs attached. Although the effect of these so-called dummy EDAPs is insignificant to the PCU perfor-mance it is not recommended to create those.

In PCU2, the dummy EDAPs should not be used. By not creating any EDAP in PCU the system ensures that the load caused by the GPRS channels is divided evenly between PCU internal resources.

CS-3 and CS-4 capable networkWhen activating the CS-3 and CS-4 coding schemes application software in a GPRS-only or a mixed GPRS/EGPRS network, the following requirements must be met in target cell:

• Licence for CS-3 and CS-4 enabled • EDGE capable TRXs • BTS software has to support CS-3 and CS-4 • Dynamic Abis

CS-3 and CS-4 requires Dynamic Abis Pool (EDAP). EDAP should be dimensioned and defined for all TRXs supporting CS-3 and CS-4 based on needed data throughput. All BTSs connected to EDAP should be taken into account when defining proper EDAP size.

When CS-3 and CS-4 are activated in a mixed GPRS/EGPRS network, the initial EDAP size can be defined by the normal EDAP size recommendations.

Note that CS-3 and CS-4 are not activated when the PCU1 and PCU2 are plugged in the same track in different BCSUs because the PCU1 does not support CS-3 and CS-4.

For more information on CS-3 and CS-4, see GPRS Coding Schemes in GPRS System Feature Description under Feature Descriptions/Existing Features/Packet Switched Data. For more information on EDAP dimensioning, see Abis EDGE Dimensioning under Plan and Dimension.

EDGE networkThe PCU2 architecture removes limitation for number of EDAP because PCU2 uses DSP resources more optimal way. There is no recommendation for number of EDAP’s in PCU2.

In PCU1, the recommended number of EDAP’s is 1, 2, 4, or 8.

A PCU2-D or a PCU2- U with 8 DSPs can handle the same number of EDAPs as a PCU1 with 16 DSPs. The maximum number of EDAPs for PCU2-D and PCU-U is 16.

In PCU2-E, the maximum number of EDAPs is 60 and the total number of DSPs for handling the EDAPs is 6.

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PCU2 in BSC Network configuration


You should avoid creating dummy EDAPs also in a pure EDGE configuration to evenly distribute the load among DSPs.

Gb interfaceThe Gb dimensioning and recommendations are the same for both PCU1 and PCU2. For more information, see Gb EDGE Dimensioning under Plan and Dimension.

Mixed PCU1 – PCU2 HW configuration in the same BSCThe BSC supports two types of mixed PCU1-PCU2 hardware configurations, that is, symmetric and asymmetric.

In a symmetric configuration, all the BCSUs have an identical PCU configuration, that is, in every BCSU, the same type of PCU is used in a certain slot. There are no specific restrictions in this configuration. However, the PCU variant specific features are sup-ported only on the cells served by the proper PCU variant.

In an asymmetric configuration, there are different PCU variants in the same slot in dif-ferent BCSUs. To ensure a successful BCSU switchover the following limitations should be considered in an asymmetric configuration:

• If any of the PCU1 units has a limited Abis connectivity (128 channels), this limitation applies to all PCUs in that slot, including PCU2.

• CS-3 and CS-4 are not supported by any of the PCU2s in that slot. • PCU2-E cannot be installed on the same slot with a different type of PCU (PCU2-D

or PCU-B).

PCU2 in Packet AbisPCU2 connectivity with Packet Abis has the same timeslot and bit rate as that of Legacy Abis. EDAP is not used when the connection is Packet Abis.

• PCU2-E - ETPT InterfacePCU2-E is connected to ETPT with ethernet datalink. This connection is needed for PS data transfer.PCU2-E ------- ESB ------- ESB ------- ETPTORPCU2-E ------- ESB -------external switch -------ESB ------- ETPTETPT uses IP protocol for host-to-host communication and UDP protocol for process-to-process communication between ETPT and PCU2-E.

• PCU2-D - ETPT InterfaceETPT is connected PCU2-Ds via the hotlink interface that connects the ETPT to GSWB. On the hotlink interface, ETPT supports HDLC data links towards PCU2-Ds. There is a separate HDLC data link for every PCUDSP. This means that one ETPT supports to 256 HDLC data links. ETPT – PCU2-D connection is needed for PS data transfer.

• PCU2-E - ETPE InterfacePCU2-E is connected to ETPE with ethernet datalink. This connection is needed for PS data transfer.PCU2-E ----- ESB ----- ESB ------- ETPEETPE uses IP protocol for host-to-host communication and UDP protocol for process-to-process communication between ETPE and PCU2-E.

• PCU2-D - ETPE InterfaceETPE is connected PCU2-Ds via the hotlink interface that connects the ETPE to GSWB. ETPE – PCU2-D connection is needed for PS data transfer.

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Network configuration

For more information, see BSS21454: Packet Abis over Ethernet and BSS21440: Packet Abis over TDM.

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4 Operability of PCU2 in BSC

4.1 Hardware and software configuration managementHardware configurationIn the PCU2 solution, there are three PCU2 plug-in unit variants: PCU2-D is used for BSC3i, PCU2-U is used for the older BSC version and PCU-E is used for BSC3i and Flexi BSC. You can create and connect PCU1 and PCU2 with the same MML com-mands.

Software configurationThe PCU2 consists of the following new software modules:

• Flash Boot for the PowerQuicc • Boot archive that contains PowerQuicc SW - OSE operating system, PCU2 platform

software, and PCU2 application software • Three DSP SW modules: boot, diagnostics, and applications.

Implementing PCU2 in BSCThe main difference between the PCU1 and PCU2 installation is that in PCU2 it is easier to load the boot software, that is the flash image for PQ. In GPRS/EDGE HW upgrade the check and possibly required loading of the boot SW are handled by a macro. In case the boot software needs to be loaded in CD installation, follow the hardware and software (CD) installation procedures introduced in CD Installation Instructions docu-mentation. That documentation contains instructions for manual loading of the PCU2 boot software.

4.2 Operator parametersThere are some differences in the use of operator parameter between PCU1 and PCU2.

SW Module PCU2-D PCU2-U PCU2-E

PQ RAM image IGWMNPQD.IMG IGWMNPQU.IMG IGWMNPQE.IMG

DSP diagnostics image IGWDGDSD.IMG IGWDGDSU.IMG IGWDGDSE.IMG

DSP boot image IGWBTDSD.IMG IGWBTDSU.IMG IGWBTDSE.IMG

DSP RAM image IGWMNDSD.IMG IGWMNDSU.IMG IGWMNDSE.IMG

Flash image for PQ IGWBTPQD.IMG IGWBTPQU.IMG IGWBTPQE.IMG

PQ RAM image with Packet Abis Software

IGWMPPQD.IMG - IGWMPPQE.IMG

DSP RAM image with Packet Abis Software

IGWMPDSD.IMG - IGWMPDSE.IMG

Table 2 PCU2 software image names

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Operability of PCU2 in BSC

Class Number Name Function PCU1 use

PCU2 use

Notes

046 0046 MEMORY_OUT_FLAG_SUM

Memory out flag sum

Yes Yes

046 0047 EGPRS_UPLINK_PENALTY

EGPRS uplink penalty

Yes Yes

046 0048 EGPRS_UPLINK_THRESHOLD

EGPRS uplink threshold

Yes Yes

046 0049 EGPRS_DOWNLINK_PENALTY

EGPRS downlink penalty

Yes Yes

046 0050 EGPRS_DWNLINK_THRESHOLD

EGPRS downlink thresh-old

Yes Yes

046 0051 GPRS_UPLINK_PENALTY GPRS uplink penalty

Yes Yes

046 0052 GPRS_UPLINK_THRESHOLD

GPRS uplink threshold

Yes Yes

046 0053 GPRS_DOWNLINK_PENALTY

GPRS downlink parameters

Yes Yes

046 0054 GPRS_DOWNLINK_THRESHOLD

GPRS downlink threshold

Yes Yes

046 0055 UPLNK_RX_LEV_FRG_FACTOR

Uplink Rx-level forgetting factor

Yes Yes

046 0059 TERRIT_BALANCE_THRSHLD

Territory balance threshold

Yes Yes

046 0060 TERRIT_UPD_GTIME_GPRS

GPRS territory update guard time

Yes Yes

046 0061 TBF_LOAD_GUARD_THRSHLD

TBF load guard threshold

Yes Yes

046 0062 TBF_SIGNAL_GRD_THRSHLD

TBF signal guard threshold

Yes Yes

046 0064 PRE_EMPTIVE_TRANSMISSIO

Pre-emptive transmission

Yes Yes

046 0066 BCCH_BAND_TBF_THRSHLD

BCCH band TBF threshold

Yes Yes

046 0067 DL_TBF_RELEASE_DELAY

Downlink tempo-rary block flow release delay

Yes Yes

046 0068 UL_TBF_RELEASE_DELAY

Uplink temporary block flow release delay

Yes Yes

046 0071 UL_TBF_REL_DELAY_EXT

Uplink TBF release delay in extended mode

Yes Yes

Table 3 PRFILE parameter differences between PCU1 and PCU2

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046 0072 UL_TBF_SCHED_RATE_EXT

Uplink TBF scheduling rate in extended mode release delay

Yes No PCU2 uses parameter POLLING_INTERVAL_BG(default)/IA/STRM for this purpose

046 0085 POLLING_INTERVAL_STRM

POLLING INTERVAL STRM

No Yes

046 0086 POLLING_INTERVAL_IA POLLING INTERVAL IA

No Yes

046 0087 POLLING_INTERVAL_BG POLLING INTERVAL BG

No Yes

046 0090 PFC_PFT_LEGACY_STRM PFC PFT LEGACY STRM

No No

046 0091 EGPRS_GPRS_MUX_PENALTY

EGPRS GPRS MUX PENALTY

No Yes

046 0092 GPRS_UL_MUX_DEC_FACTOR

GPRS UL MUX DEC FACTOR

No No

046 0093 EGPRS_DL_MUX_DEC_FACTOR

EGPRS DL MUX DEC FACTOR

No No

046 0094 NCCR_STOP_DL_SCHEDULING

NCCR stop downlink sched-uling

No No out of use, NCCR

046 0095 NCCR_STOP_UL_SCHEDULING

NCCR stop uplink schedul-ing

No No out of use, NCCR

046 0096 NCCR_NON_DRX_PERIOD

NCCR Non DRX Period

Yes Yes NCCR

046 0097 NCCR_MEAS_REPORT_TYPE

NCCR measure-ment report type

Yes Yes NCCR

046 0099 SUSPEND_PCU_LOAD_NOTIF

PCU Load Notifi-cation lifetime

No No

046 0100 CHA_CONC_UL_TBF_FAV_DIR

CHA_CONC_UL_TBF_FAVOR_DIR

No Yes

046 0101 CHA_CONC_DL_TBF_FAV_DIR

CHA_CONC_DL_TBF_FAVOR_DIR

No Yes

046 0102 PFC_PFT_MAX_NRT PFC_PFT_MAX_NRT

No No

046 0103 PFC_PFT_MAX_RT PFC_PFT_MAX_RT

No No


PCU2 use

Notes

Table 3 PRFILE parameter differences between PCU1 and PCU2 (Cont.)

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046 0105 DTM_CALL_ASSIGN_TIMER

DTM call assign-ment timer

No Yes

046 0106 MAX_LAPD_LENGHT Maximum LAPD message length

No Yes

046 0107 DTM_MS_CL_11_SUPP_EDA

DTM Multislot Class 11 mobile extended dynamic alloca-tion mode support

No Yes

046 0109 IBNACC_POLLING_TIME IBNACC polling time

No No

046 0110 LBNCCR_MIN_INTERVAL_PLR

LBNCCR Minimum Interval Between PS Load Reports

No No

046 0111 QOS_UPGRADE_TIME QoS upgrade time

No No

046 0113 POLLING_INTERVAL_BG_LOW

Polling interval BG low

No Yes

046 0114 POLLING_INTERVAL_IA_LOW

Polling interval IA low

No No

046 0115 POLLING_INTERVAL_ST_LOW

Polling interval ST low

No No

046 0116 DL_DTM_TBF_REL_DELAY

Downlink tempo-rary block flow release delay for DTM call

No Yes

046 0117 UL_DTM_TBF_RELDELAY_EXT

Uplink TBF release delay for DTM call in extended mode

No Yes

046 0118 UL_DTM_TBF_REL_DELAY

Uplink temporary block flow release delay for DTM call

No Yes

049 0 TNS_BLOCK NS level block timer

Yes Yes NS

049 1 TNS_RESET Timer for NS level reset

Yes Yes NS

049 2 TNS_TEST Timer for NS level test

Yes Yes NS

049 3 TNS_ALIVE Timer for NS level alive proce-dure

Yes Yes NS

049 5 NS_BLOCK_RETRIES NS block retries Yes Yes NS


PCU2 use

Notes


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049 6 NS_UNBLOCK_RETRIES NS unblock retries

Yes Yes NS

049 7 NS_ALIVE_RETRIES NS alive retries Yes Yes NS

049 8 NS_RESET_RETRIES NS reset retries Yes Yes NS

049 9 TGB_BLOCK Timer of GB block

Yes Yes BSSGP

049 10 TGB_RESET Timer for Gb reset

Yes Yes BSSGP

049 11 TGB_SUSPEND Timer for Gb suspend

Yes Yes BSSGP

049 13 BVC_BLOCK_RETRIES BVC block retries Yes Yes BSSGP

049 14 BVC_UNBLOCK_RETRIES BVC unblock retries

Yes Yes BSSGP

049 15 BVC_RESET_RETRIES BVC reset retries Yes Yes BSSGP

049 16 SUSPEND_RETRIES Suspend retries Yes Yes GPRS Suspend

049 20 FC_R_DIF_TRG_LIMIT R_dif limit value Yes Yes DL Flow control

049 21 FC_MS_R_DEF MS-specific leak rate default value

Yes Yes DL Flow control

049 22 FC_MS_R_DEF_EGPRS MS-specific leak rate default value for EGPRS


049 23 FC_MS_R_MIN Minimum value of MS leak rate


049 24 FC_MS_B_MAX_DEF Buffering capacity default value


049 25 FC_MS_B_MAX_DEF_EGPRS

Buffering capacity default value


049 26 FC_R_TSL GPRS timeslot transmission capacity


049 27 FC_R_TSL_EGPRS EGPRS timeslot transmission capacity


049 28 FC_B_MAX_TSL GPRS timeslot buffering capacity


049 29 FC_B_MAX_TSL_EGPRS EGPRS timeslot buffering capacity



PCU2 use

Notes


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049 31 TSNS_PROV Timer for sub-network service procedures

Yes Yes Gb Over IP

049 32 SNS_ADD_RETRIES Sub-network service add retries

Yes Yes Gb Over IP

Parameter is delivered to the PCU, but it is not in use, because BSC initiated Add proce-dure is not supported.

049 33 SNS_CONFIG_RETRIES Sub-network service config retries

Yes Yes Gb Over IP

049 34 SNS_CHANGEWEIGHTS_RETRIES

Sub-network service change-weights retries

Yes Yes Gb Over IP

Parameter is delivered to the PCU, but it is not in use, because BSC initiated Change-weight proce-dure is not supported.

049 35 SNS_DELETE_RETRIES Sub-network service delete retries

Yes Yes Gb Over IP

049 36 SNS_SIZE_RETRIES Sub-network service size retries

Yes Yes Gb Over IP

049 37 TGB_RAC_UPDATE TGB RAC UPDATE

Yes Yes RA Capability Update

049 38 RAC_UPDATE_RETRIES RAC UPDATE RETRIES

Yes Yes RA Capability Update

049 0052 CONVERSATIONAL_ARP1 Priotity class conversational and traffic class 1

No No


No No


No No


PCU2 use

Notes


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049 0055 STREAMING_ARP1 Priotity class streaming and traffic class 1

No No


No No


No No

049 0058 INTERACT_PRIOR_1_ARP1

Priotity class interactive 1 and traffic class 1

No No



No No



No No



No No



No No



No No



No No



No No



No No

049 0067 BACKGROUND_ARP1 Priotity class background and traffic class 1

No Yes


No Yes


No Yes

049 72 RESUME_RETRIES Resume retries Yes Yes GPRS Resume


PCU2 use

Notes


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For a list of all related parameters, see PRFILE and FIFILE Parameter List and BSS Radio Network Parameter Dictionary under Reference/Parameters.

Scheduling step sizeIn the PCU2, the new bucket round-robin (BRR) scheduling algorithm replaces the priority-based scheduling used in the PCU1. The following are the related radio network parameters for scheduling step sizes for priority level in the PCU1:

• DL high priority SSS (DHP)

• DL normal priority SSS (DNP) • DL low priority SSS (DLP)

• UL priority 1 SSS (UP1)

• UL priority 2 SSS (UP2)

• UL priority 3 SSS (UP3) • UL priority 4 SSS (UP4)

The corresponding parameters for PCU2 are:

• background traffic class scheduling weight for ARP 1 (BGSW1) • background traffic class scheduling weight for ARP 2 (BGSW2)

• background traffic class scheduling weight for ARP 3 (BGSW3)

The existing scheduling step size values can be converted into the scheduling weight values as shown in the following table:

The upgrade macro converts and updates values of the PCU1 specific Scheduling Step Size parameters to the corresponding PCU2 parameters.

Extended uplink TBF scheduling rateThe extended uplink TBF scheduling rate parameters are used differently for PCU1 and PCU2.

049 73 TGB_RESUME Timer for Gb resume

Yes Yes GPRS Resume

049 0082 PS_NULL_NRI_SUPPORT PS_NULL_NRI support

No Yes


PCU2 use

Notes


SSS Weight SSS Weight

1 60 7 9

2 30 8 8

3 20 9 7

4 15 10 6

5 12 11 5

6 10 12 5

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In the PCU1, UL_TBF_SCHED_RATE_EXT defines the next block period when a TBF in the extended mode is given a transmission turn. However, a TBF in the extended mode cannot have better residual capacity than it would in the normal mode.

In the PCU2, POLLING_INTERVAL_BG defines the time in block periods during which the TBF in the extended state cannot have transmission time. The parameter is the same for all traffic classes. After the POLLING_INTERVAL has elapsed, the TBF is returned to scheduling and it gets a transmission turn when the scheduler decides so.

Delayed downlink TBF polling rateThe delayed downlink TBF polling rate is different for the PCU1 and PCU2.

In the PCU2, POLLING_INTERVAL_BG defines the time in block periods how often the mobile station (MS) is polled during the delayed downlink TBF release.

In the PCU1, the time cannot be adjusted with any parameter.

BLER limitsBLER limits are needed for the Quality Control function and for the Link Adaptation (LA).

The maximum block error rate (BLER) limit is set with different parameters in the PCU1 and PCU2.

For PCU1 (with the ZEQV command):

• maximum BLER in acknowledged mode (BLA)

PCU2 PCU1

How often a USF is scheduled for the MS during the inactivity period in Extended uplink TBF mode.

Defined by the PRFILE parameter: POLLING_INTERVAL_BG.

Recommended value is 4 block periods (80 ms).

PCU2 SW ED upgrade macro sets the PCU2-specific POLLING_INTERVAL_BG parameter into its recom-mended value.

Defined by PRFILE parameter: UL_TBF_SCHED_RATE_EXT.

Default value is 80 ms (every 4 block periods).

Table 4 Extended uplink TBF scheduling rate

PCU2 PCU1

How often the MS is polled during delayed downlink TBF release.

Defined by the PRFILE parameter: POLLING_INTERVAL_BG.

Recommended value is 4 block periods (80 ms).

PCU2 SW ED upgrade macro sets the PCU2-specific POLLING_INTERVAL_BG parameter into its recom-mended value.

Defined by RLC RTT. New poll is sent as soon as the MS has responded to previous poll.

Typical value is 220 ms (every 11 block periods).

Table 5 Delayed downlink TBF polling rate

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• maximum BLER in unacknowledged mode (BLU)

For PCU2 (with the ZEEV command):

• PFC ack BLER limit for transfer delay 1 (ABL1)

• PFC unack BLER limit for SDU error ratio 1 (UBL1)

Packet flow context (PFC) feature is not applicable with BSC SW. Only the ABL1 and UBL1 parameters are used, although all ABL1-5 and UBL 1-6 parameters are visible. All BLER limit parameters are visible regardless of the state of the PFC feature.

In Quality Control function the above corresponding parameters are used similarly in both PCU1 and PCU2. The BLER parameter values are not directly comparable though, so they are not converted in the upgrade. See also Link Adaptation below.

Link AdaptationThe GPRS Link Adaptation (LA) algorithm is different in PCU1 and PCU2. The EGPRS LA algorithm is the same. For more information, see Link Adaptation for GPRS and Link Adaptation for EGPRS in GPRS System Feature Description and EDGE System Feature Description under Feature Descriptions/ Existing Features/ Packet Switched Data.

In the PCU1, the LA algorithm selects the coding scheme based on the BLER estimate. BLER is estimated for each TBF based on the successfully and unsuccessfully transmit-ted/received RLC data blocks.

In the PCU2, the LA algorithm selects the coding scheme based on the channel quality measurements made by the RLC receivers. In downlink data transfer it is the RXQUAL value received from the MS and in uplink data transfer it is the BEP measurement received from the BTS. The PCU2’s GPRS LA algorithm covers all the coding schemes CS-1, CS-2, and also CS-3 and CS-4 if the CS-3 and CS-4 application software is acti-vated.

The LA algorithm in the PCU1 operates only in the RLC acknowledged mode. In the RLC unacknowledged mode, the PCU1 uses always CS-1. The LA algorithm in the PCU2 operates in both in the RLC acknowledged and RLC unacknowledged modes.

The LA algorithm in the PCU2 can be operated in two different modes:

• In adaptive mode (ADAPTIVE LA ALGORITHM = TRUE), the look-up tables that are used for RXQUAL -> BLER mapping are updated automatically based on the statis-tics gathered from the TBF connections.

• In non-adaptive mode (ADAPTIVE LA ALGORITHM = FALSE), the look-up tables have constant values that have been determined by means of simulations.

The LA algorithm in the PCU1 uses the following parameters (MML command ZEQO):

• DL adaption probability threshold (DLA) • DL BLER crosspoint for CS selection hop (DLBH)

• DL BLER crosspoint for CS selection no hop (DLB)

• UL adaption probability threshold (ULA) • UL BLER crosspoint for CS selection hop (ULBH)

• UL BLER crosspoint for CS selection no hop (ULB)

The LA algorithm in the PCU2 uses the following parameters (MML command ZEQO):

• DL coding scheme in acknowledged mode (DCSA)

• UL coding scheme in acknowledged mode (UCSA)

DN70505952 27



• DL coding scheme in unacknowledged mode (DCSU) • UL coding scheme in unacknowledged mode (UCSU)

• adaptive LA algorithm (ALA)

as well as the following parameters (MML command ZEEO):

• PFC ack BLER limit for transfer delay 1 (ABL1)

• PFC unack BLER limit for SDU error ratio 1 (UBL1)

The Link Adaptation parameters for PCU1 and PCU2 are not directly comparable and they are therefore not converted in the upgrade.

GPRS capacity throughput factorGPRS capacity throughput factor parameter defines the segment's GPRS capacity throughput factor. This is used when calculating the PCU DSP need in automatic PCU selection and PCU2 pooling. The GPRS capacity throughput factor (GCTF parameter) has a default value of 80%, which means that the PCU tries to reserve DSP resources for a segment so that 80% of the default channel capacity is served with highest coding scheme supported by segment's territory type. This parameter is used in Packet Abis PCU and it is applicable only for PCU2.

4.3 MaintenanceService terminalThe PCU2 service terminal is enhanced from the PCU1 service terminal. The syntax of the service terminal (ST) commands as well as the set of available commands and command functionalities are also different. The PCU2 has, for example, new monitoring commands for testing and fault finding purposes. For more information, see PCU2 Service Terminal Commands under Reference/Commands.

A list of available commands with short introductions can be printed on the PCU2 service terminal with the “help” command, which displays a short syntax help. The “help” command can always be replaced by a question mark.

Note that the PCU2 service terminal is case-sensitive and uses mainly lower case letters.

Log systemThe size of default log buffer is 1.5 MB in the PCU2 and 32 kB in the PCU1. In both PCU types the buffer is ring buffer. In the PCU2, the system start-up logs are stored.

In both of the PCU variants, the critical logs are transferred to the OMU’s disk as a default without any action needed from your part. The PCU1 also stores the critical and error logs to the PCU’s log buffer as default, but in the PCU2 log buffering must be set ON separately for the critical and error logs with the command efl (enable file logging).

The default log level (for critical logs) is ON after a PCU2 reset. The other log levels can be set ON by the PCU2 service terminal command sll (select log level). The log levels that are ON can be seen by using the command dld (display log details). For more infor-mation, see PCU2 Service Terminal Commands under Reference/Commands.

The recommended log level for optimum system performance is the default log level. The other log levels should only be used on Nokia Siemens Networks' advice.

In the PCU2, all the telecom applications have the same log levels.

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In the PCU2, the logs can be transferred out faster via an IP connection than via an OMU connection. Therefore it is recommended to map the IP address for the PCU2.

Note that when setting the log levels manually, the settings remain until the PCU2 is reseted.

AlarmsThe following new alarms are PCU2-specific:

• 1301 PCU DIGITAL SIGNAL PROCESSOR RESTARTThe PCU DSP has not answered to a supervision message sent from the PCU Power Quicc processor, or the DSP has reported that a critical process running on it has died.Because of the failure, the signal processor and the data channels handled by it are temporarily out of use.The PCU Power Quicc processor tries to reload and restart the DSP.This is a disturbance that does not require user actions.

• 3298 PCU DIGITAL SIGNAL PROCESSOR FAILUREThe PCU2 has not been able to recover from a digital signal processor (DSP) failure.Because of the failure, the signal processor and the data channels handled by it are out of use.This is a two star alarm that triggers a BCSU switchover. Note that the PCU1 uses the alarm 3012 DIGITAL SIGNAL PROCESSOR FAILURE for permanent DSP fail-ures. In the PCU1, no BCSU switchover is performed because of a DSP failure. The PCU2 does not support alarm 3012.

• 3523 PCU2-ETP Serial link failureSerial link between packet control unit (PCU) and Exchange Terminal for Packet Transport (ETP) has failed. Cells connected to the PCU have lost General Packet Radio Service.

• 3524 PCU2-ETP Ethernet link failureEthernet link between packet control unit (PCU) and Exchange Terminal for Packet Transport (ETP) has failed. Cells connected to the PCU have lost General Packet Radio Service.

The following alarms have been modified for the PCU2:

• 0125 PCU PROCESSOR LOAD HIGHThe purpose of this notice is to provide an early warning on a PCU processor load situation. The notice is set when a PCU processor load is approaching the level where the overload protection actions are started. As a default this notice is not in

0 LOG_NULL Switching off the logs

1 LOG_WARNING Warning level logs for debugging purposes

2, 3, 4, 5 LOG_INFO Information logs for debugging purposes

6 LOG_ERROR Error logs which do not impact system operations, to be taken for all modules

11 LOG_CRITICAL Error logs which impact system oper-ations, to be taken for all modules

DN70505952 29



use, that is, the notice has to be enabled by setting a PRFILE parameter. The notice does not require cancelling.In the PCU2. this notice is set when either the PQ or DSP load is approaching the overload levels, whereas in the PCU1 this notice is set only by a PQ load situation.

• 3164 PCU PROCESSOR OVERLOADThis two-star alarm is set when the PCU processor load has activated the first PCU overload protection actions, to protect the service provided for the current active users served by the PCU. The alarm is cancelled when the load has fallen below the overload levels.In the PCU2, this alarm is set when either PQ or DSP load has reached the overload levels and the overload protection begins, whereas in the PCU1 this notice is set only by PQ load situation.

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Key performance indicators and counters for PCU2

5 Key performance indicators and counters for PCU2

5.1 Benchmarking KPIsWhen introducing a new PCU generation, some changes are expected to be seen in key performance indicator (KPI) and statistical counter values, and this should be noted when comparing statistics from cells under the different PCUs variants. A difference in KPI demonstrates a different behaviour between the PCU plug-in unit variants. The fol-lowing table shows how the benchmarking KPI values are expected to change in similar and comparable configuration and traffic conditions. For more information on definitions of the KPI formulas, see EDGE, GPRS, and GSM Voice Key Performance Indicators under Reference / Counters/Performance Indicators.

As a main principle, all available PCU counters and KPIs are comparable because the counter triggering is based on the same logic in both PCU variants. The exceptions to this rule are presented in Counter differences.

DN70505952 31

PCU2 in BSC Key performance indicators and counters for PCU2


KPI Group KPI name Formula ID Expected difference

Network Usage

Uplink RLC payload trf_243 Improvement in EGPRS throughput allows more payload in the same time in PCU2. Observed improve-ment depends heavily on traffic model of network.

Downlink RLC payload

trf_244 Improvement in EGPRS throughput allows more payload in the same time in PCU2. Observed improve-ment depends heavily on traffic model of network.

DTM PS payload ratio

dtm_3 Comparison not possible, because DTM is supported only by PCU2.

PS Erlangs trf_237d No difference.

Relative share of PS Erlangs

trf_242a No difference.

Downlink GPRS Erlangs

trf_208c No difference.

Uplink GPRS Erlangs

trf_205d No difference.

Downlink EGPRS Erlangs

trf_162f Lower in PCU2. Less Erlangs are needed for the same amount of data due to better EGPRS throughput.

Uplink EGPRS Erlangs

trf_161i Lower in PCU2. Less Erlangs are needed for the same amount of data due to better EGPRS throughput.

UL signaling TBFs usage ratio

tbf_61 No difference.

Share of EDGE requests


User Experi-ence

Volume weighted LLC Throughput

llc_3a Higher in PCU2. PCU2 has better EGPRS RLC throughput, which gives also better LLC throughput, when EDGE is used. Observed improvement depends heavily on traffic model of network.

Volume weighted LLC throughput for GPRS

llc_4a Higher in PCU2. PCU2 takes advantage of CS-4 to achieve better RLC throughput, which improves LLC throughput as well. Observed improvement depends heavily on traffic model of network.

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Availability Data service avail-ability ratio

ava_68 No difference.

PDTCH congestion

DL multislot alloca-tion blocking

tbf_16a Direct comparison not possible because of counter updating difference.

DL multislot soft blocking

blck_33a No difference.

Downlink TBFs per timeslot

tbf_38d No difference.

PDTCH quality

Downlink GPRS RLC throughput

trf_235b No difference with CS-1 and CS-2 in PCU2. Improve-ment with CS-3 and CS-4.

Uplink GPRS RLC throughput

trf_233c No difference with CS1 & CS2 in PCU2. Improvement with CS3 & CS4.

Downlink EGPRS RLC throughput

trf_236 Higher in PCU2. PCU2 uses air interface and internal resources more efficiently. New LA algorithm look-up table used in PCU2 causes lower coding schemes to be used in difficult radio condi-tions, which can also cause decrease in RLC through-put per TSL, but gives better end user throughput caused by fewer RLC retransmis-sions.

Uplink EGPRS RLC throughput

trf_234 Higher in PCU2. PCU2 uses air interface and internal resources more efficiently. New LA algorithm look-up table used in PCU2 causes lower coding schemes to be used in difficult radio condi-tions, which can also cause decrease in RLC through-put per TSL, but gives better end user throughput caused by fewer RLC retransmis-sions.

TBF establishment failure ratio


TBF success ratio tbf_67 No difference.

Mobility DL flush per minute tbf_64 Decrease in DL flush per minute.

Abis con-gestion

Inadequate EDAP resources in downlink

dap_7a Improvement in PCU2 (lower value) due to PCU2 hardware and new EDAP congestion handling.


DN70505952 33



5.2 Counter differencesBy default, all counters work in the same way in the PCU1 and PCU2, that is, the trig-gering points for updating the counters are the same for both PCU variants. The excep-tions are listed below.

72058 UL TBF RELEASE DUE TO FLUSH

In rare occasions the PCU1 already has released the UL TBF when flush message arrives, while the PCU2 still keeps the TBF alive. In these occasions this counter is updated in the PCU2, but not in the PCU1.

72070 BAD_FRAME_IND_UL_CS1

The PCU2 updates this counter only when UL TBF is in the active state, which results in lower values than in the PCU1, which updates counter already in the establishment phase of the TBF.

72079, 72080 NO RADIO RES AVA UL TBF, NO RADIO RES AVA DL TBF

The PCU2 updates the counters 72079 and 72080 only if no resources are available for a new establishment/reallocation. The PCU1 is also updated when no better resources are available and the TBF continues with old allocation.

72093, 72095 DL_TBF_ESTABLISHMENT_FAILED, DL_EGPRS_TBF_REL_DUE_NO_RESP

The PCU2 is optimised in a situation where an attempt is made to establish DL TBF using old DL resources via the PDA. In a situation where the MS has already sent PDAN (FAI=1) and started the timer T3192 and the MS does not start using these resources sent in the PDA, the PCU2 does not update the DL_TBF_ESTABLISHMENT_FAILED/ DL_EGPRS_TBF_REL_DUE_NO_RESP_MS counter, but tries to establish the TBF via the CCCH. Even if this proactive DL TBF re-establishment fails, the PCU2 does not update the DL_TBF_ESTABLISHMENT_FAILED/ DL_EGPRS_TBF_REL_DUE_NO_RESP_MS counter.

In the same situation where the MS does not start using resources sent in the PDA, the PCU1 instead updates the DL_TBF_ESTABLISHMENT_FAILED/DL_EGPRS_TBF_REL_DUE_NO_RESP_MS counter and freezes the resources for 5 seconds and tries DL TBF establishment just after 5 seconds.

72168, 72069, 72070 AVE BUSY GPRS CH UL, AVE BUSY GPRS CH DL, AVE BUSY GPRS CH DEN

These sampling based counters are updated every second in the PCU2 and every fifth second in the PCU1.

072265 UL MCS reduction due to PCU resources

PCU con-gestion

DL MCS selection limited by PCU

dap_9 Improvement in PCU2 (lower value) due to PCU2 hardware and new EDAP congestion handling.

Gb conges-tion

Downlink Gb load frl_8a No difference.


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The counter is updated only in case of Packet Abis when uplink MCS is reduced due to PCU resources. This counter is not updated for PCU1.

072266 DL MCS reduction due to PCU resources

The counter is updated only in case of Packet Abis when downlink MCS is reduced due to PCU resources. This counter is not updated for PCU1.

5.3 Indirect effects of other implementation differences in countersSome implementation differences in the functionality indirectly cause differences in the counter values. These differences are listed here. The scale of difference depends heavily on network configuration and traffic profile.

72001 MAX_DUR_UL_TBF

As a default the PCU2 prefers 4+1 allocation, while the PCU1 prefers 3+2 allocation. This will usually result a higher value for MAX_DUR_UL_TBF.

72028, 72033, 72039, 72049, 72149 DL_TBF_RE_ALLOCATIONS, DL_TBF_REALLOC_FAILS, REQ_1_TSL_DL, ALLOC_1_TSL_DL, REQ_1_TSL_DL_FOR_EGPRS_MS

In the PCU2, during DL TBF establishment on the CCCH (due to DLPDU), if the MS RAC (radio access capabilities of mobile station) is known, the PCU2 allocates the required number of TSLs to the DLTBF immediately, based on the multislot class of the MS.

Out of these assigned TSLs, the PCU2 selects one TSL and this TSL is indicated in the Immediate Assignment message. Once the DLTBF is established, a PDA message is sent out to the MS in which the complete DL channel allocation is informed to the MS.

In the PCU1, initially only 1 TSL is allocated in the DL, and later on a channel reallocation is done to move to multiple TSLs and the DL_TBF_RE_ALLOCATIONS counter is incre-mented.

So if DL TBF is established on the CCCH and the number of TSLs needed to allocate is more then one in DL direction then DL_TBF_RE_ALLOCATIONS is incremented. This also increases the probability of DL_TBF_REALLOC_FAILS. Furthermore, ALLOC_1_TSL_DL , REQ_1_TSL_DL/REQ_1_TSL_DL_FOR_EGPRS_MS will be incremented every time by the PCU1 in these cases.

This implementation difference causes higher value of these counters with the PCU1.

72059, 72061 DL_TBF_REL_DUE_TO_FLUSH, DL_TBF_REL_DUE_TO_SUSPEND

The values of these counters are typically lower in the PCU2 than in the PCU1, because when the FLUSH or SUSPEND message is received by the PCU2, DL TBF has been already released by the PCU2 more frequently than the PCU1. This is due to the differ-ent handling of delayed DL TBF when UL TBF exists for the MS.

The PCU2 releases DL TBF when a maximum of 5.7 seconds has been reached in the delayed state. In the same situation the PCU1 maintains DL TBF in the delayed state until UL TBF is released.

73001, 79002 RETRANS_DL_RLC_MAC_BLOCKS, UL_RLC_BLOCKS_IN_ACK_MODE

The values of these DL RLC/MAC block counters show in many cases lower values than the PCU1. This is due to differences in MCS selection, enhanced LA algorithm and more

DN70505952 35



efficient dynamic Abis usage. When a new TBF is established, the PCU2 uses the MCS used most recently in the previous TBF of the MS, but the PCU1 always uses the initial MCS selected by the operator.

This causes a difference in the number of used RLC/MAC blocks. More efficient DAP usage enables higher MCS usage in good radio conditions, which decreases the number of used RLC/MAC blocks. A new enhanced LA takes a lower MCS in use earlier when radio conditions get worse, which decreases need for retransmissions.

90004 DROPPED_DL_LLC_PDUS_LIFETIME

The PCU2 attempts to re-establish DL TBF after it gets abnormally released due to N3105 condition (8 bad frames received instead of DL Ack in sequence). The PCU1, on the other hand, does not try to re-establish the DL TBF and discards all the buffered DL LLC PDUs, when DL TBF is abnormally released.

The counter DROPPED_DL_LLC_PDUS_LIFETIME is incremented in case the PCU is not able to transmit an LLC PDU to the MS in the life time specified. Since the PCU2 tries to re-establish the DL TBF, whereas, the PCU1 discards the DL LLC PDUs imme-diately on N3105, the chances of DL LLC PDU discards due to lifetime expiry are higher with the PCU2 (as the lifetime of buffered DL LLC PDUs may expire during the re-estab-lishment period - up to 2 seconds). The PDUs discarded by the PCU1 after N3105 are not counted in DROPPED_DL_LLC_PDUS_LIFETIME.

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