dynamic abis

Dynamic Abis

dn0431625Issue 1-0 en

# Nokia CorporationNokia Proprietary and Confidential

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2003353Nokia BSC/TCSM S11.5 ProductDocumentation

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2 (28) # Nokia CorporationNokia Proprietary and Confidential


Dynamic Abis

Contents

Contents 3

List of tables 4

List of figures 5

1 Overview of Dynamic Abis 7

2 Requirements for Dynamic Abis 11

3 Technical description of Dynamic Abis 133.1 Capacity-related parameters of Dynamic Abis 133.2 Abis L1 frames 143.3 GPRS TBF 163.4 EGPRS TBF 173.5 Restrictions to Dynamic Abis 17

4 Functionality of Dynamic Abis 214.1 Dynamic Abis Pool management 214.2 EGPRS Dynamic Abis Pool connections 234.3 Dynamic Abis Pool in PCU 24

5 User interface of Dynamic Abis 275.1 Parameters 275.2 MMLs 275.3 Counters 285.4 Alarms 28



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Contents

List of tables

Table 1. Software requirements for Dynamic Abis 11

Table 2. Hardware requirements for Dynamic Abis 12

Table 3. Coding schemes. Need for master (M) and slave channels (S) on Abis. 15



Dynamic Abis

List of figures

Figure 1. An example of T1 allocation 8



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List of figures



Dynamic Abis

1 Overview of Dynamic Abis

The Dynamic Abis splits Abis E1/T1 transmission lines into:

. permanent 16 kbit/s sub timeslots for signalling

. permanent 16 kbit/s sub timeslots for voice and data

. Dynamic Abis Pools (DAP) for radio timeslots that require more than 16kbit/s transmission capacity from Abis

The DAP area connected to (E)GPRS use is called the EGPRS Dynamic AbisPool (EDAP). The DAP can be shared by a number of EDGE capabletransceivers (TRX) in the same BCF cabinet. The DAP and the TRXs sharing ithave to be allocated to the same Abis E1/T1 transmission line. The followingfigure illustrates an example of T1 Dynamic Abis configuration; DAP 1 is sharedby TRXs 1, 3, and 5:



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Overview of Dynamic Abis

Figure 1. An example of T1 allocation

In the BSC there can be two different (E)GPRS territory types:

1. GPRS territory

. CS1 and CS2 packet data channels, no DAP

. CS1 - CS4 packet data channels, DAP required

TSL 1

TSL 12

TSL 13

TSL 18

TSL 24

MBCCH SDCCH TCHF TCHF

TCHFTCHFTCHFTCHF

TCHF TCHF TCHF TCHF

TCHDTCHF TCHDTCHD

TCHF TCHFSDCCHMBCCH

TCHF TCHFTCHFTCHF

TCHF

TCHF

TCHF TCHF TCHF

TCHDTCHDTCHD

TCHF TCHFSDCCHMBCCH

TCHF TCHFTCHFTCHF

TCHF

TCHF

TCHF TCHF TCHF

TCHDTCHDTCHD

TSIG5 TSIG6

TSIG4TSIG3

TSIG2TSIG1 OMU

EDGE TRX 1

TRX 2

EDGE TRX 3

TRX 4

EDGE TRX 5

TRX 6

BTS 1,SEGMENT 1

BTS 2,SEGMENT 2

BTS 3,SEGMENT 3

BCF

DAP 16 X 64k

Signaling



Dynamic Abis

2. EGPRS territory

. MCS1 - MCS9 and CS1 - CS2, DAP required

. MCS1 - MCS9 and CS1 - CS4, DAP required

Dynamic Abis is application software but it is always required with EGPRS andCS3&4.

Warning

One EDAP resource should not be shared between several BCF cabinets.This may damage the TRX or DTRU hardware if the operator tries to shareEDAP between several cabinets.

Refer to Dynamic Abis Pool Handling for operating instructions on how tohandle Dynamic Abis pools in the BSC.

Related topics

. Requirements for Dynamic Abis

. Technical description of Dynamic Abis

. Functionality of Dynamic Abis

. User interface of Dynamic Abis

. For EDGE dimensioning guidelines, see GSM/EDGE BSS SystemDocumentation Set (Plan category)



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Overview of Dynamic Abis



Dynamic Abis

2 Requirements for Dynamic AbisSoftware requirements

Table 1. Software requirements for Dynamic Abis

Network element Software release required

BSC S11.5

Nokia UltraSite EDGE BTSs For Dynamic Abis: CX3.3

For CS3&CS4: CX4.1

Nokia MetroSite EDGE BTSs For Dynamic Abis: CXM3.3

For CS3&CS4: CXM4.1

Nokia 2nd Gen. BTSs Not supported

Nokia Talk-family BTSs Not supported

Nokia PrimeSite BTSs Not supported

Nokia InSite BTSs Not supported

MSC/HLR No requirements

SGSN No requirements

Nokia NetAct OSS4



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Requirements for Dynamic Abis

Hardware requirements

Table 2. Hardware requirements for Dynamic Abis

Network element Hardware requirements

BSC PCU PIUs

For CS3&CS4: PCU2

BTS Nokia UltraSite EDGE BTS and/or NokiaMetroSite EDGE BTS

TCSM No requirements

SGSN No requirements

For an overview of Dynamic Abis, see Overview of Dynamic Abis .



Dynamic Abis

3 Technical description of Dynamic Abis

3.1 Capacity-related parameters of Dynamic Abis

Dynamic Abis pool (DAP) is a continuous block of 64 kbit/s timeslots. Themaximum size of one DAP in a PCU is 24 timeslots but the BTSs limit the usablesize into 12 timeslots. The sum of all DAPs in one PCU is 51 timeslots. There canbe a maximum of 16 DAPs per PCU. There can be up to 128 DAPs in a BSCEand BSCi, up to 256 DAPs in a BSC2E/2A/2i, and up to 384 DAPs in a BSC3i.DAP's identifier value range is 1 - 470.

The capacity of a specific EDAP depends on:

. the total number of EDAPs in the PCU

. the EDAP size

. the number of EDGE TRXs and EGPRS channels/packet data channels(PDCHs) connected to the EDAP

. the modulation and coding schemes (MCS) used in data transmission

The MCSs that are used are selected by the PCU based on the radio link qualitymeasurements and Link Adaption algorithms. Operator parameters for initialMCSs are also taken into account when selecting an MCS for data transmission.However, Dynamic Abis capacity (EDAP size and available PCU DSP resources)also affects MCS usage and because of this, Dynamic Abis and PCU capacitylimitations are also taken into account in MCS selection.

Dynamic Abis counters monitor EDAP usage and Dynamic Abis limitations. Thefollowing actions may have to be considered if the Dynamic Abis countersindicate problems in Dynamic Abis usage:



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Technical description of Dynamic Abis

. increasing EDAP size

This may help, for example, in cases where the EDAP counters indicatethat TBFs are left without requested EDAP resources, EDAP peak usage is100 %, EDAP average usage is high, but EDAP resource limitations arenot caused by the lack of PCU resources.

. decreasing the number of EDGE TRXs and/or EGPRS channels attachedto EDAP

This may help, for example, in cases where the EDAP counters indicatethat TBFs are left without requested EDAP resources and EDAP resourcelimitations are caused by the lack of PCU resources.

. sharing the load between PCUs (moving an EDAP(s) and/or GPRSchannels from one PCU to another)

This may help, for example, in cases where the EDAP counters indicatethat TBFs are left without requested EDAP resources and EDAP resourcelimitations are caused by the lack of PCU resources.

Note

EDAP size is the same for both downlink and uplink directions. It is not possibleto set different EDAP sizes for downlink and uplink directions.

3.2 Abis L1 frames

In Nokia (E)GPRS implementation PCU frames (based on TRAU frames in CS )are used to carry the PS traffic over Abis. One PCU frame uses 16kbit/s subtimeslot. There are following PCU frame types:

. PCU data frame

- used when TRX is not in EDGE mode and is able to carry CS-1 andCS-2

. PCU master data frame

- used when TRX is in EDGE mode and carries CS-1 or MCS-1 on itsown and CS-2...CS-4 and MCS-2...MCS-9 with the help of slaveframe(s)

. PCU slave data frame(s)



Dynamic Abis

- carry additional data that does not fit in PCU master data frames

. PCU random access frame

- used only in uplink direction to carry access burst information

. PCU synchronisation frame

- used after territory upgrade for synchronising PCU with BTS radiotimeslots

Master and slave channels with different coding schemes

PCU slave data frames are transferred in the EDAP area and they are alwaysassociated with the PCU master data frames transferred in the permanent 16 kbit/ssub timeslots. The following table displays the number of 16 kbit/s sub timeslotsrequired by different coding schemes.

Table 3. Coding schemes. Need formaster (M) and slavechannels (S) on Abis.

CS/MCS

Need for masterand slavechannels

CS1 M

CS2 M+S

CS3 M+S

CS4 M+S

MCS1 M

MCS2 M+S

MCS3 M+S

MCS4 M+S

MCS5 M+S

MCS6 M+ 2*S

MCS7 M+ 3*S

MCS8 M+ 4*S



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Table 3. Coding schemes. Need formaster (M) and slavechannels (S) on Abis.(cont.)

CS/MCS

Need for masterand slavechannels

MCS9 M+ 4*S

The MS may use a lower CS/MCS for uplink data transmission than the CS/MCSfor which uplink EDAP resources have been reserved.

3.3 GPRS TBF

In the BSC, there can be separate territories for GPRS and EGPRS. In GPRS loadsituations or when a GPRS territory does not exist, it is possible that GPRS traffic(GPRS TBFs) uses EGPRS territory. When a GPRS TBF is via GPRS territory(via a non-EDGE TRX), the CS-2 coding scheme needs only 16 kbit/s from Abis.When a GPRS TBF is via CS-3 and CS-4 capable GPRS territory or via EGPRSterritory (via an EDGE TRX), the CS-2 coding scheme needs a 16 kbit/s masterAbis channel and one 16 kbit/s slave channel from the EDAP. This is because theEDGE TRX uses different PCU frame formats and synchronisation schemes. CS-3/CS-4 always uses EDAP.

If a 16 kbit/s slave channel for a GPRS TBF cannot be found, for examplebecause of EDAP load situations, the coding schemes CS-2 - CS-4 cannot beused. In the uplink direction, the MS's transmission turn may have to be rejected.In the downlink direction, CS-1 may be used instead of CS-2 - CS-4 in certaincases. Appropriate counters are updated.

For more information, see (E)GPRS in BSC .



Dynamic Abis

3.4 EGPRS TBF

The GPRS RR procedures apply to EGPRS as well. The difference comes fromthe EGPRS's need for more than 16 kbit/s Abis transmission capacity. The masterAbis channel is always linked to a PDTCH . The rest of the required Abistransmission is allocated from the EDAP in 16-64 kbit/s blocks, depending on thecoding scheme (MCS) used. The Dynamic Abis resource information and codingscheme is told to the BTS by inband signalling in the PCU master data frametransferred on the master Abis channel.

If enough 16 kbit/s slave channels for the coding scheme (MCS) used by theEGPRS TBF cannot be found because of the EDAP load situation, the desiredcoding scheme cannot be used. In the uplink direction, the MS's transmission turnmay have to be rejected. In the downlink direction, a lower coding scheme maybe used instead of the desired coding scheme in certain cases. Appropriatecounters are updated.

3.5 Restrictions to Dynamic Abis

Only Nokia UltraSite EDGE BTSs and Nokia MetroSite EDGE BTSs are able touse Dynamic Abis allocation. Furthermore, only EDGE capable TRXs (EDGETRX) are capable of using shared EGPRS Dynamic Abis Pool (EDAP) resources.

PCUPCM allocation restrictions

. One EDAP cannot be divided to separate PCUPCMs.

. DSP HW restriction: one PCUPCM TSL (64 kbit/s = 4 x 16 kbit/ssubTSLs) must be handled in one DSP core.

. The system does not allow an EDAP area to overlap with another EDAParea or with (E)GPRS channels on PCMs.

Internal PCU1 restrictions

. In one logical PCU1 there are 16 digital signal processor (DSP) cores. In aPCU1, one DSP core can handle only one EGPRS dynamic Abis pool(EDAP), but one EDAP can be shared by several DSP cores. The DSPcores sharing an EDAP must be either odd or even DSP cores.

. In the PCU1s, one DSP core can handle 0 to 20 channels (16 kbit/s),including active EDAP channels, EGPRS channels, GPRS channels, andPBCCH/PCCCHs. The maximum number of 16 kbit/s channels per PCU is256.



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A DSP core attached to EDAP can handle 16 radio timeslots, so four slavechannels are needed in order to reach the maximum number of channels.

. All EGPRS channels of one EDGE TRX must be handled in the DSP corewhich handles the related EDAP. If an EDAP is handled in several DSPcores, the EGPRS channels of one EDGE TRX can be divided to severalDSP cores in a PCU1.

. In the uplink direction, the PCU1 allocates uplink EDAP resources for thehighest CS/MCS granted for an MS during the TBF's lifetime.

. In PCU1 there is one synchronisation master channel (SMCH) for everyEDAP. Due to DSP restrictions, the SMCH must be allocated onPCUPCM0. To ensure that each EDAP has SMCH candidates onPCUPCM0, the PCU1 reserves a number of sub timeslots from PCUPCM0exclusively for each EDAP, that is, for the EGPRS and PBCCH/PCCCHchannels on the TRXs attached to the EDAP.

. PCU and PCU-S can handle 128 radio timeslots. This issue should betaken into account in PCU dimensioning.

Internal PCU2 restrictions

. In one logical PCU2 there are 8 digital signal processor (DSP) cores. In aPCU2, one DSP core can handle two EGPRS dynamic Abis pool (EDAP),but one EDAP can be shared by several DSP cores.

. In the PCU2s, one DSP core can handle 0 to 40 channels (16 kbit/s),including active EDAP channels, EGPRS channels, GPRS channels, andPBCCH/PCCCHs. The maximum number of 16 kbit/s channels per PCU2is 256. Note that the maximum sum of EGPRS channels, GPRS channels,and PBCCH/PCCCHs is 32 per DSP core so to reach 40 channels therehave to be at least 8 EDAP channels.

. All EGPRS channels of one EDGE TRX must be handled in the DSP corewhich handles the related EDAP. Because of the Enhanced Quality ofService (EQoS) functionality in PCU2 all the channels of a TRX must beon the same DSP core.

. In PCU2 there is one synchronisation master channel (SMCH) for everyDSP. The PCU2 can allocate the SMCHs to both PCUPCMs 0 and 1.



Dynamic Abis

Common restrictions for both PCU1 and PCU2

. EDAP resource usage in a PCU dynamically reserves the DSP resources inthe PCU. When EGPRS and GPRS calls (TBFs) in EGPRS territory useEDAP resources, allocation of the new PSW radio timeslots to the PCUmay fail due to the current EDAP and DSP resource load.

. When new PSW radio timeslots are added/upgraded to the PCU, the PCUDSP resource capacity used for the EDAPs decreases. This may lead to asituation where the desired CS/MCS cannot be assigned to the TBFs. Indownlink direction, the TBFs can adjust the downlink data according tolimited Dynamic Abis capacity. In uplink direction, the PCU DSP resourceload situation may cause a situation in which the uplink transmission turnscannot be assigned for the MSs, for example if adequate uplink DynamicAbis resources cannot be allocated.

. The EDAP size itself also limits the CS/MCS usage for both downlink anduplink TBFs.




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Dynamic Abis

4 Functionality of Dynamic Abis

4.1 Dynamic Abis Pool management

Dynamic Abis is application software. However, the Dynamic Abis is mandatoryto enable EGPRS or CS3/CS4 support in the BSC and in the PCU. If DynamicAbis is used, the operator must define the pool to be used by the TRX. It must belocated on the same PCM as TRXSIG and the fixed traffic timeslots.

Activating Dynamic Abis Pool for (E)GPRS use

The operator can allocate common transmission resources for EDGE-capableTRXs from the Abis ET-PCM. This common resource is called the Dynamic AbisPool (DAP) and it is comprised of consecutive Abis ET-PCM timeslots. Therecan be several DAPs in one Abis ET-PCM but normally only one is needed. TheDAP has to be created before the EDGE TRXs using the DAP are created to theAbis ET-PCM. If the operator wants to change the TRX's usage of Dynamic Abis,they can attach or detach a DAP from the TRX.

When a DAP is created, the BSC reserves the corresponding block of timeslotsfrom the PCUPCM. These PCUPCM circuits are needed when DAP circuits areconnected to EGPRS use. The BSC downgrades all packet switched trafficchannels from the PCU and then upgrades these same traffic channels to packetswitched use again. This short interruption ensures that the BSC can find a blockof free timeslots from the PCUPCM and to ensure optimised PCU DSP resourceusage for each DAP connected to the PCU. Refer to Creating dynamic Abis poolfor operating instructions on how to handle Dynamic Abis pools in the BSC.

Dynamic Abis Pool modification

The operator can change the size of the Dynamic Abis Pool (DAP) by addingAbis ET-PCM time slots to DAP, or by removing Abis ET-PCM time slots fromDAP. The integrity of the DAP is kept up in these operations. This means thatnew Abis ET-PCM time slots are added to either upper or lower edge of the DAPand Abis ET-PCM time slots are removed from either upper or lower edge of theDAP.



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Functionality of Dynamic Abis

When new Abis ET-PCM time slots are added to DAP, the BSC reserves acorresponding block of time slots from PCUPCM. These PCUPCM circuits areneeded when DAP circuits are connected to EGPRS use. The BSC downgradesall packet switched traffic channels from PCU and then upgrades these sametraffic channels to packet switched use again. This short interruption ensures thatthe BSC can find a block of free time slots from the PCUPCM and to ensureoptimised PCU DSP resource usage for each DAP connected to the PCU.

The operator can also change the controlling PCU of the DAP. When the DAP'sPCU is changed, the BSC downgrades all packet switched traffic channels fromboth the old and the new PCU and then upgrades these same traffic channels topacket switched use again. This short interruption ensures optimised PCU DSPresource usage for each DAP connected to those PCUs. If there are one or moreTRXs attached to that pool, the packet switched channels of the segments of theTRXs are upgraded to the new PCU. Refer to Modifying Dynamic Abis pool foroperating instructions on how to handle Dynamic Abis pools in the BSC.

Dynamic Abis Pool deletion

The operator can delete Dynamic Abis Pool (DAP) when there are no TRXsattached to it. The BSC releases all resources reserved for the DAP when it isdeleted. The BSC downgrades all packet switched traffic channels from the PCUand then upgrades these same traffic channels to packet switched use again. Thisshort interruption ensures optimised PCU DSP resource usage for each otherDAP connected to the PCU. Refer to Deleting Dynamic Abis pool for operatinginstructions on how to handle Dynamic Abis pools in the BSC.

Dynamic Abis Pool circuit routings

Circuit routings are needed for Abis ET-PCM circuits to utilise the Dynamic Abisfeature in BSC. The BSC makes these routings automatically when DynamicAbis Pool (DAP) is created, modified or deleted.

The BSC adds Abis ET-PCM circuits to a circuit group named 'ET-PCM' at thesame time as the Abis ET-PCM circuits are added to DAP. This prevents other useof these Abis ET-PCM circuits while they belong to the DAP. The ET-PCMcircuit group is common for all DAP circuits.

The BSC has also own circuit group for every DAP. These DAP circuit groupsare named to 'DAPxxx', where 'xxx' indicates Dynamic Abis Pool number withthree digits. The DAP circuit group is specially designed for Dynamic Abis and itenables hunting and connection methods required by Dynamic Abis. The BSCadds DAP circuits to the DAP circuit group as one bit wide circuits which are inascending order according to timeslots and subtimeslot. The BSC changes statesof these circuits from BA to WO at the same time as the circuits are added tocircuit group.



Dynamic Abis

Note

It is not allowed to make changes to DAP routings manually even if it is possiblewith MML commands provided by the DX 200 platform. Removing DAProutings causes malfunction of the Dynamic Abis.

4.2 EGPRS Dynamic Abis Pool connections

The procedure where Dynamic Abis pool (DAP) circuits are connected toEGPRS use is called the EDAP upgrade procedure and the procedure where DAPcircuits are removed from EGPRS use is called the EDAP downgrade procedure.If GPRS service is provided with an EDGE TRX, EDAP circuits may also beused for GPRS. In EDAP upgrade and downgrade the BSC downgrades allpacket switched traffic channels from the PCU and then upgrades these sametraffic channels to packet switched use again. This short interruption ensuresoptimised PCU DSP resource usage for each DAP connected to the PCU.

EGPRS Dynamic Abis Pool upgrade

The BSC performs the EDAP upgrade procedure when:

1. the DAP is created

2. new circuits are added to the DAP

3. the PCU controlling the DAP is restarted

There are two phases in the EDAP upgrade procedure. In the first phase the BSCmakes connections between Abis ET-PCM circuits and PCUPCM circuits. In thesecond phase the BSC attaches DAP circuits to EDAP by informing the PCUabout mappings between the Abis ET-PCM circuits and the PCUPCM circuits.

The BSC connects DAP circuits to EDAP starting from the last circuit and thenconnecting the next circuit from the side of previous circuit as long as there arecircuits configured to (E)GPRS use. EDAP is always comprised of consecutiveDAP circuits. All the circuits belonging to the DAP are connected to the EDAP.

EGPRS Dynamic Abis Pool downgrade

The BSC starts the EDAP downgrade procedure when:

1. the DAP is deleted

2. circuits are removed from the DAP



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There are two phases in the EDAP downgrade procedure. In the first phase theBSC detaches DAP circuits from the EDAP by informing the PCU about changedmappings between Abis ET-PCM circuits and PCUPCM circuits. In the secondphase the BSC releases connections between the Abis ET-PCM circuits and thePCUPCM circuits.

BCSU (PCU) restart

When the BCSU is restarted the BSC releases all EDAP connections related tothe BCSU. After the PCU becomes operational again, the BSC runs an upgradeprocedure for each EDAP controlled by the PCU. The PCU shares the DSPresources optimally for all the EDAPs when the BCSU (PCU) is restarted.

BCSU (PCU) switchover

If a switchover is made for the BCSU, the BSC releases all EDAP connectionsrelated to the old BCSU and then starts an upgrade procedure to recover theEDAP connections in the new BCSU. The PCU shares the DSP resourcesoptimally for all the EDAPs in BCSU (PCU) switchover.

4.3 Dynamic Abis Pool in PCU

A PCU shares DSP resources optimally for EDAPs when a new dynamic Abispool is created or an existing pool is deleted or modified. DSP resources are alsoshared after BCSU restart or switchover. A PCU shares all (working) DSP coresbetween all EDAP's connected to the PCU by using a PCU internal algorithm.PCU DSP resources for an individual EDAP depends on the total number ofEDAPs for the PCU and on EDAP-specific properties (EDAP size and attacheddefault EGPRS channel count). Because the following formulas use the EDAP-specific default EGPRS channel count, BCSU switchover is recommended whenthe default EGPRS channel count is changed, in order to maintain optimal PCUDSP resource sharing for EDAPs.

First the PCU calculates the ideal DSP core count for each EDAP:

where

IdealDSPcoreCountForEDAP=EDAPsizeIn16kbit/sChannels + DefaultEGPRSchannels+ PBCCH_PCCCHs

20



Dynamic Abis

. EDAPsizeIn16kbit/sChannels is EDAP size in 16 kbit/s PCM subTSLs

. DefaultEGPRSChannels is the sum of default EGPRS channels of all theTRXs (BTSs) attached to the EDAP

. PBCCH_PCCCHs is the number of PBCCH/PCCCH channels

. 20 is the 16kbit/s channel handling capacity of a single PCU DSP core

The ideal DSP core count is rounded upwards.

If the result of the algorithm that calculates the ideal DSP core counts for eachEDAP indicates that all available DSP cores are not needed for EDAPs, the PCUmay dedicate DSP cores also for GPRS channels, that is for the radio timeslots ofTRXs not attached to any EDAP. The PCU calculates the maximum number ofGPRS-dedicated DSP cores with following formula:

DSP_need_for_GPRS = def_gprs_tchs_no_dap / 20

where

. def_gprs_tchs_no_dap is the number of default GPRS channels

. 20 is the 16 kbit/s channel handling capacity of a single PCU DSP core

The result is rounded downwards.

Special configurations for algorithm:

. If there are no EDAPs defined for a PCU, all DSPs are dedicated forGPRS.

. If there is only one EDAP for PCU, one DSP group (even or odd) is forEDAP and the others dedicated for GPRS (PCU1 only).

. If there are 16 EDAPs for PCU, all DSPs must be used for EDAPs andthere are no GPRS dedicated DSPs.

Only GPRS channels are allowed to GPRS-dedicated DSPs. Both GPRS andEGPRS channels are allowed to a DSP assigned for EDAPs.

For each EDAP, the PCU calculates the EDAP DSP load based on the ideal DSPcore count for that EDAP:

DSP_EDAPload=EDAPsizeIn16kbit/sChannels + DefaultEGPRSchannels+ PBCCH_PCCCHs

IdealDSPcoreCountForEDAP



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If the sum of ideal DSP core counts for all EDAPs in the PCU differs from theavailable DSP core count, the PCU adjusts DSP resources for each EDAPaccording to the available DSP core count as follows.

If the sum of ideal DSP core counts for all EDAPs in the PCU is less than theavailable DSP core count, the PCU dedicates DSP cores for GPRS as mentionedabove, and if there are still unassigned DSP cores after GPRS dedication, theextra DSP cores are allocated to the EDAPs, starting from the EDAP with thehighest DSP EDAP load.

If the sum of ideal DSP core counts for all EDAPs in the PCU is more than theavailable DSP core count, the PCU decreases the DSP core count for the EDAPsthat have the lowest DSP EDAP loads until the sum of allocated DSP core countsequals the available DSP cores. However, each EDAP gets at least one DSP core.The PCU tries to minimize the relative effect with more than one EDAP with thesame DSP EDAP load, as the PCU decreases the highest DSP core count first.

PCU DSP resources assigned to an EDAP may limit the usage of EDAPresources and PCU capacity for new GPRS channels.

A possible but a bad configuration example:

. One EDAP containing 12 TSLs and 15 EDAPs containing 2 TSLs each areconfigured to one PCU1. The first EDAP is handled in one DSP core, andthe EDAP has 48 channels. Only 16 EDAP channels of the first EDAP canbe used by 4 EGPRS channels.




Dynamic Abis

5 User interface of Dynamic Abis

5.1 Parameters

Radio network parameters:

. identification (ID)

. Abis interface ET-PCM number and first TSL of the pool(CRCT)

. pool size (SIZE)

. BCSU-unit which handles PCU (BCSU)

. PCU-unit which handles PCU PCMs (PCU)

. new first timeslot (NFT)

. new last timeslot (NLT)

. TRX(s) connected to pool(s) (TRXS)

. dynamic Abis pool ID (DAP)

For more information, see BSS Radio Network Parameter Dictionary.

5.2 MMLs

The following MML is used to handle Dynamic Abis Pool:

. Abis Interface Configuration (ES )



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User interface of Dynamic Abis

5.3 Counters

The Dynamic Abis introduces new measurements and counters. The followingmeasurements are related to Dynamic Abis:

. 1 Traffic Measurement

. 76 Dynamic Abis Measurement

The purpose of Dynamic Abis Measurement is to help the operator to monitorand control the usage of EDAPs and to give the operator better possibilities toconfigure and optimize for example EDAP sizes. There are separate counters forboth uplink and downlink measurements. Traffic Measurement contains countersfor partially successful and failed territory upgrade requests, for example.

5.4 Alarms

The alarm EGPRS DYNAMIC ABIS POOL FAILURE (3068 ) is set in thefollowing cases:

. if the BSC cannot attach DAP circuits to EDAP (all successfully connectedDAP circuits are attached to EDAP)

. if the BSC cannot connect one DAP circuit to EDAP because ofconnection failure

. if an EDAP configuration update or an EDAP modification to PCU fails

PCU capacity (for example, PCU DSP resource load for on-going EGPRS callsusing EDAP resources) may start limiting the EGPRS and GPRS RR procedures.It is possible that new GPRS TCHs cannot be added to the PCU. Thereforeterritory upgrades fail either partly or completely. The alarm (E)GPRSTERRITORY FAILURE (3273 ) is set, if the (E)GPRS territory size in the BTS isbelow the limit specified by the BTS-specific radio network parameter defaultGPRS capacity (CDEF) . The BSC has not been able to add more radiochannels to the territory within informing delay. The BSC's ability to transfer (E)GPRS traffic in the BTS has been reduced or totally prevented.




Dynamic Abis

dynamic abis

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