ps core signaling evolution

EUGAP Meeting No. 31: Jakarta; November 25 - 27, 2013; 1

Signalling Evolution Packet Core Paul Bramich

Senior Solution Architect, Ericsson


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What is the main contributing factor to signalling load increases for Packet Core?

A. Rise of smartphones B. Popularity of different Apps C. New usage patterns D. Changed device behavior E. LTE topology RAN direct to core

Main contributing factors

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Rise of Smartphones & tablets

Popularity & variety of apps

New usage pattern & device behavior

In LTE, direct exposure of Core to eNodeBs

Main contributing factors


The e2e smartphone challenge overview


The e2e smartphone challenge overview

Data traffic

RAN

con

trol

pla

ne lo

ad

Feature phones

PCs

Data: IP packets to/from apps, services, Internet Signaling: Mobile-specific messages for managing mobility and resources for Data traffic

Significant signaling x

Many smartphones =

Impact on some networks

Signalling load increasingly important with smartphones

Smart Phones


Why EPC signalling concerns?

Rapid uptake of popular LTE Smartphones ...which have a chatty traffic behaviour just

as for 3G

Frequent idle-to-active mode transactions Reduced phone battery consumption Increased cell capacity Controlled by the LTE RAN idle timer

LTE architecture without central controller Inter-base station mobility events visible in

EPC


0

10

20

30

40

Op1 Op2 Op3 Op4

10s 20s 61s 61s

HOSR

Live OPERATOR EXAMPLES No of Service requests/BH/SAU

The lower the idle timer value, the higher the signalling load on EPC

EPC network dimensioning need to consider that this impact is mainly controlled by RAN

0

10

20

30

40

50

60

4s 10s 10s 20s 20s 61s 61s RAN idle timer

SR/SAU/B

0

30

0 60 120

SRHO

Simulated impact of Idle Timer

s

1/BH/SAU Signaling rates in 4 LTE

networks with different Idle Timer settings

1/BH/SA

RAN idle timer

SR/SAU/Bhr

Signaling rates in 4 LTE networks with different Idle

Timer settings

1/BH/SAU


E2e network impacts

10

MME

SGW

HSS HLR/ AuC

eNB UE

Paging increases over radio interface

RRC signalling increases over radio interface

Service Request signalling request

increases to re-establish the RAB

Re-Authentication signalling request increases due to

Selective Authentication on every nth UE procedure

PGW

ENIQ Event Based Monitoring Data Transaction increase

Send Authentication Information Transaction increase

Paging Request increase to re-establish RAB for downlink traffic being buffered more often due to being in idle state quicker

Modify Bearer Message increase to notify SGW and PGW of RAB state change from CONNECTED to IDLE and IDLE to CONNECTED

Downlink Data Notification increase from PGW to SGW and then to MME to trigger paging to UE for re-establish RAB due to being in idle state quicker

S1-U S5-C

S5-U

Gr

RAN Utilisation Savings due to less

connected states


Operator 1 Operator 2

Operator 3

LTE world range

Signaling UE / RAN =>

Frequency per SAU per BH

3G LTE only

After LTE launch

Before LTE

launch

LTE connected

subs

Customer under study

(current)

MME GGSN2) SGW2)

Attach 0.9 0.1 3.7 0.1 - 7 0.2 -

Detach 0.04 0.1 0.03 0.1 0.1 ()

PDP / Bearer Activation 0.2 3 0.75-0.80

1 0.2 - 5 0.3

Service Request 4.4 7.2 7 3.74 7.7 (100%) 3 60 2-4 ()

S1 / Iu Release 12 13.9 17 12 20 (100%) 3 60 17-32 -

Paging 2.7 6.6 10 1.5 8.4 (500%) 1 - 20 2 - 3)

Intra-SGSN-MME RAU/TAU1)

1.8 3.9 0.5-0.8 .5-.8 0.2 5 0.9 - -4)

Intra-RAT HO1) (X2 / SRNS...)

3.2 0.1 2.6 1 - 25 -

Inter-SGSN-MME RAU/TAU with W=>L IRAT

1 6.6 - - 0.5 - 8 0.02

Signaling impact assumptions:

1) Intra-RAT, Intra-SGSN-MME

2) SGW: LTE, S11. GGSN: WCDMA, Gn, no 3GDT

3) Mainly DL data notifications before paging

4) No SGW relocation

potential Signaling impact

Ultimately, traffic profile will depend on device mix, user behavior, apps & RAN design etc


35sec Inactivity timer

0

500

1000

1500

2000

2500

3000

0:00:00 0:00:09 0:00:17 0:00:26 0:00:35 0:00:43 0:00:52 0:01:00 0:01:09 0:01:18

Repeat mo-Data request from same M-TMSI (VXE8 MME - National LTE RAN) - ZOOMED

Count

Count of Top 10

All repeat activities handled in same

connected state with 35 sec timer setting

Larger sample size than next slide


10sec Inactivity timer

0

1000

2000

3000

4000

5000

6000

7000

0:00:00 0:00:09 0:00:17 0:00:26 0:00:35 0:00:43 0:00:52 0:01:00 0:01:09 0:01:18

Normalised Count of Time between repeated Service Request for MoData from same M-TMSI - National (VXE8 MME)

All Subscribers

Top 10 Subscribers per Repeat Activity Delta Time Point

Large spikes also seen at 15 and 20

secs.

Large spikes also seen at 15 and 20

secs.

This could be due to device issues or configuration and is limited to only a handful of

individual UEs

At 11 secs there is a considerable request to

reactivate the RAB given it has just gone idle.


Network impacts of RAN timer changes

MME (S1 and S11 interfaces) ~100% increase in Service Request Procedures ~30% increase in LTE paging over S1 interface ~30% increase in Modify Bearer Requests over S11 interface

SGW/PGW (S11 & S5 interface) ~30% increase in Modify Bearer Requests received over S11 interface and S5 (internal/external) to PGW ~30% increase in Downlink Data Notification sent to SGW over S5 (internal/external) and S11 interface to MME. ~Session Controller board CPU impacts.

HSS (S6a & HLR/AUC i/f for Auth) ~10% increase in S6a Authentication Procedures. ~10% increase in MAP Send Authentication Procedures between the HSS and HLR

RAN Increased signalling over the air interface due to paging and RAB establishment request increases. *Better capacity utilisation of radio interface (e.g. PRBs, SR etc.) due to less time spent in connected state.


Why reduce LTE RAN Idle timer?

A. Because Apple said to B. To save RAN bearers C. To improve battery life D. So Ericsson can sell more

So why do it????

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So why do it???

Battery Life


Feature roadmap overview Feature 3GPP? GSM WCDMA LTE

Smart and Adaptive Paging No 2013A 2013B 2010B

Selective SR Handling No - 2011A -

UE Signalling Control No 2011A 2011A 2011A

Dynamic TAI List Control Yes - - 2012A

Attach Throttling ? - - 2013A

Smart and Adaptive Paging feature reduces signaling load by up to 90%

Selective Service Request Handling features enable the SGSN-MME to selectively handle which radio access bearers (RABs) to re-establish elimination of unnecessary setup of multiRABs within the radio

network up to 50% makes room for more users and directly impacts the needed investment


Smart Adaptive Paging


Selective Service Request Handling


UE Signalling Control

GSM, WCDMA & LTE applicable!


Smartphone signalling demo

Please check with your local Ericsson representative to secure the Smartphone signalling demo


Slide Number 1Important setup!Lets check your EUGAP awareness!Main contributing factorsMain contributing factorsThe e2e smartphone challengeoverviewThe e2e smartphone challengeoverviewWhy EPC signalling concerns?Live OPERATOR EXAMPLESNo of Service requests/BH/SAUE2e network impactspotential Signaling impact35sec Inactivity timer10sec Inactivity timerNetwork impacts of RAN timer changesSo why do it????So why do it???Feature roadmap overviewSmart Adaptive PagingSelective Service Request Handling UE Signalling ControlSmartphone signallingdemoSlide Number 22

ps core signaling evolution

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