Common_lac_action Plan.ppt

Common LAC Implementation

Content  Background  Problem description  LA updates in 2G Vs. combined 2G/3G networks  Recommended steps  Consideration, Common 2G/3G LA’s  Summary/Conclusion

Ericsson Confidential

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Common LAC Implementation

2008-07-08

Background 

Customer complaints about missed calls –

Terminating calls rerouted to customer voice mail box



Many operators are experiencing increased load from paging and location updates in their combined 2G/3G networks



Both problems are amplified by the increased part of dual mode terminals



Many networks have initially been rolled out with an overlay 3G architecture with inferior coverage compared to 2G.



These conditions will remain, although getting less frequent.

Ericsson Confidential

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Common LAC Implementation

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Content  Background  Problem description  LA updates in 2G Vs. combined 2G/3G networks  Recommended steps  Consideration, Common 2G/3G LA’s  Summary/Conclusion

Ericsson Confidential

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Common LAC Implementation

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Problem description 

Parallel 2G and 3G coverage and no restrictions for subscribers to roam between both accesses result in high volume of inter-system Location Updates –



Terminating calls to subscribers during the events below will fail –



Typically 2.5 seconds per Inter-MSC LU Typically 2 seconds per Intra-MSC LU The UE stops listen to 3G page typically 2.5 s (large variation) prior to LU request

Terminals cannot be paged during the RA Update procedures (when camping on 2G) –



Second page won’t help unless above procedures are completed

Terminals cannot be paged during the LU procedures – – –



Two types: 1) Inter- and 2) intra-MSC Location Updates (LU)

Similar times as for LU are valid for RA Update

Terminals also need time to find and tune in to new paging channel after a Location Update –

Typically 3 seconds (large variation)

Ericsson Confidential

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Common LAC Implementation

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LU type normal, 2G only ”Horizontal” LU’s limited to LA border areas Few but processing demanding procedures for LU’s. HLR

MSC

MSC

BSC

BSC

2G LAI 123-01-1

MSC Pool can improve the LU and paging characteristics by reducing the number of inter MSC LU’s.

2G LAI 123-01-2

LU’s limited to border areas, hence not so big issue with paging deafness due to the low number of MT calls during LU procedure

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LU type normal, separate 2G/3G core ”Vertical” LU’s anywhere in the LA Large volume of Inter-MSC LU’s HLR

1st and 2nd page often to old LA (old MSC) MSC-S

MSC

MSC MGw

BSC

BSC

RNC

Subscribers may suffer from paging deafness & poor availability. 2G LAI 123-01-1

LU’s may occur anywhere within the LA depending on the signal strength.

2G LAI 123-01-2

3G LAI 123-01-3

3G LAI 123-01-4

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Common LAC Implementation

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LU type normal, common 2G/3G core ”Vertical” LU’s anywhere but within the same MSC Same volume of LU’s but faster Intra MSC LU’s HLR

BSC

MSC-S

MSC-S

MGw

MGw

BSC

RNC

1st page most often in correct LA. Global 2nd page definitely in correct LA.

RNC

Drastically improved paging success rate!

2G LAI 123-01-1

2G LAI 123-01-2

3G LAI 123-01-3

3G LAI 123-01-4

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Common LAC Implementation

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LU type normal, common 2G/3G core with common LA’s ”Vertical” LU’s anywhere but within the same MSC LU’s are not needed for terminals that support common LA’s (unknown figure today).

HLR

BSC

MSC-S

MSC-S

MGw

MGw

BSC

RNC

RNC

Drastically increased paging. 3G calls also paged in 2G and vice versa.

Further improved paging success rate (for supporting terminals)! 2G LAI 123-01-1

2G LAI 123-01-2

3G LAI 123-01-1

3G LAI 123-01-2

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Common LAC Implementation

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Content  Background  Problem description  LA updates in 2G Vs. combined 2G/3G networks  Recommended steps  Consideration, Common 2G/3G LA’s  Summary/Conclusion

Ericsson Confidential

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Common LAC Implementation

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LAU + RAU Separate Core  12-15 Sec Common Core Sep LAIs  8-9 Sec Common LAC  3-4 Sec

Paging and LU analysis Common core, separate LAI’s

Separate 2G and 3G core H

A

Common core, common LAI S

E

S

S

S

MG

MG

MG

B

R

MG

B

B

R

R 2G LAI-1

2G LAI-1

2G LAI-1

3G LAI-1

Supporting terminals 3G LAI-2

3G LAI-2

1. Stop listen 2. LU req. to 3G page

1. Stop listen to 3G page

4. Listen to 1. Stop listen 2. LU req. to 3G page 2G page

3. LU acc.

4. Listen to 2G page

3. LU acc.

2.5s

5.5 s

Non-supporting terminals 1. Stop listen 2. LU req. to 3G page

2.5s

2.5s

2. Listen to 2G page

4. Listen to 2G page

3. LU acc.

2s 3s tot 7.5s (excluding RAU)

tot 8s (excluding RAU) Ericsson Confidential

2.5s

3s

11

tot 7.5s (excluding RAU)

Common LAC Implementation

2s 3s 2008-07-08

Content  Background  Problem description  LA updates in 2G Vs. combined 2G/3G networks  Recommended steps  Consideration, Common 2G/3G LA’s  Summary/Conclusion

Ericsson Confidential

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Common LAC Implementation

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Recommended steps for improved paging success rate 1. Tune threshold values for Inter-system LU/HO to minimize “pingponging” 2. Check dimensioning of signaling links and SDCCH channels. 3. Try the Super Charger MDE. HLR subscriber data is kept in VLR to reduce VLR-HLR signaling. 4. Migrate to Dual Access to reduce the LU times, and RAU times and secure that paging is done in correct MSC. 5. Use 2nd page, increase default 4s time supervision for 1st paging to 8-10s -Higher probability for a successful page. 6. Possibly also adjust time supervision for 2nd, default 7s, maximum 10s 7. Migrate to common PLMN id for 2G and 3G to reduce terminal load for LU’s

8. Introduce Common LA for 2G and 3G access. Ericsson Confidential

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Common LAC Implementation

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Content  Background  Problem description  LA updates in 2G Vs. combined 2G/3G networks  Recommended steps  Consideration, Common 2G/3G LA’s  Summary/Conclusion

Ericsson Confidential

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Common LAC Implementation

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Consideration, Common 2G/3G LA’s  Some terminals would still do Location Update between 2G and 3G in a common LA  Important features which improve paging characteristics will not work – – – –

Partial Roaming, Access Restriction Data (Roaming Service Restriction) Gs-interface, MDEPs..

 The paging load would increase – Both accesses are always paged, big issue in many markets – LA to be redimensioned?  Max paging per second (120-150 per second)

 Roaming subscribers get access to both 2G and 3G services – CS: MDEP to allow VT calls based on IMSI analysis (BS3G) – PS: Feature QoS Based on IMSI

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Common LAC Implementation

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Content  Background  Problem description  LA updates in 2G Vs. combined 2G/3G networks  Recommended steps  Consideration, Common 2G/3G LA’s  Summary/Conclusion

Ericsson Confidential

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Common LAC Implementation

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Summary/Conclusion 

An overlay 3G network is an obvious way to introduce 3G without disturbing the 2G operations –



Safe learning period, simple implementation projects

As the number of 3G and dual mode terminals increases some critical issues have to be taken care of. –

High LU load, paging deafness etc.



Ericsson strongly recommend to migrate to MSS with dual access to diminish the paging and LA/RA issues

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Common Location Areas could be introduced provided that the mentioned considerations are being handled.

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Common 2G/3G RA is being investigated and is a candidate for future releases (2008 SGSN Feature Package 01 Q3 2008).

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Common LAC Implementation

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Abbreviations

MRD LA RA EIR LAI MDE

Market Requirement Description Location Area Routing Area Equipment Identity Register Location Area Identity Market Development

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Extra slides on measurement results

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LAC Unification improvement in time of reselection in live Nw Time of reselection for different scenarios • When RNC and BSC are in different MSS and different LAC --> 12-15 seg. • When RNC and BSC are in same MSS and different LAC

-->

8-9 seg.

• When RNC and BSC are in same MSS and LAC --> 3-4 seg (only RAU is done).

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Common LAC Implementation

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Measurements in lab 

Inter System Change WCDMA to GSM

1.9s (RA update part measured on the Gb interface)



Intra SGSN Routing Area Update

1.1s (measured on the Iub interface)



Inter SGSN Routing Area Update

1.7s (measured on the Iub interface)

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Intra MSC location update

0.7s (measured on the Iub interface)



2G->3G IRAT

4s (measured at UE from leaving RAT until ready to listen to paging in new RAT)



3G->2G IRAT

8.5s (measured at UE from leaving RAT until ready to listen to paging in new RAT)

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