Urban-128709201967490

For internal use only / 1 © Nokia Siemens Networks

Přetížení mobilních sítí, iPhone efekt, a co by nás tak ještě mohlo potkat.


Co je za tím I. ?

• Většina operátorů mobilních sítí nedávno začala s masivním prodejem „Smartphones“

Google, iPhone, Nokia 97 ...

• Aplikace, které umožňují uživatelům online připojení jsou velmi oblíbené

email, instant messaging, presence ...

• Smartphone aplikace zatěžují signalizační kanály (tzv. Control Plane) daleko více než standardní služby typu CS, PS a HSPA.

• Zatížení signalizačních kanálů vyžaduje, aby operátoři mobilních sítí a jejich dodavatelé WCDMA RAN technologií přijali určitá opatření.


Co je za tím II. ?

Výrobci mobilních telefonů :

„Musíme snížit spotřebu,

jinak budou naši

zakázníci nabíjet mobil i vícekrát denně:

Fast Dormancy“

Vývojáři aplikací :

„Naši klienti chtějí být online.

Musíme jim to umožnit:

Keep alive messages“

Operátoři mobilních sítí a jejich dodavatelé technologií :

„Vše pro spokojenost klientů !

Jak ale optimalizovat síť, když do ní stále někdo vrtá“

Uživatel


Some networks are suffering from Smartphones


Trocha teorie.


Radio Resource Control States

Cell PCHCell PCH

Cell FACHCell FACH

URA PCHURA PCH

RRC Connection Establishment

Dedicated ModeDedicated Mode

Idle ModeIdle Mode

Cell PCHCell PCH

Cell FACHCell FACH

URA PCHURA PCH

RRC Connection Release

Cell DCHCell DCH

RRC Connection Release


Smart phone impact to HSPA networks3GPP HSPA Radio Resource Control (RRC) States

3GPP standard

1. RRC states in WCDMA RAN are designed to allow

• low UE power consumption, • high network efficiency• low response times to services

2. Large amount of data is carried on Cell DCH state

3. Small amount of data is carried on Cell FACH

4. Cell/URA PCH state is used for UE power saving

Cell DCH

Cell FACH

IDLE

Cell/URA PCH

>0.5 kB

Data volumes

<0.5 kB

UE power consumption

>200 mA

>100 mA

<5 mA

<5 mA

= RRC connected

= IDLE

RAB setup


Smart phone impact to HSPA networks3GPP HSPA RRC State Changes

3GPP standard compliant solution:

1. RRC state changes are controlled by network parameters

2. Terminal is moved from Cell DCH to Cell FACH and further to Cell PCH based on inactivity. The typical optimized parameters are 2-3 seconds (use of short timers)

3. Optimal parameter settings use short times and are designed for low mobile (smart) phone power consumption and long battery life

Cell DCH

Cell FACH

Idle

Cell/URA PCH

2-3 s inactivity

2-3 s inactivity

Data volume >0.5 kB

= RRC connected

= IDLE

RAB setup

NSN RNCs have these features included since many years (RAN1.5 onwards, 2003).


Smart phone impact to HSPA networks3GPP HSPA RRC State Changes3GPP standard compliant solution:• Cell PCH feature required to optimally

support smart phone behavior. Positive effects:

1.Less RNC control plane capacity needed

– Cell PCH state feature provides a major increase in number of UEs with RRC connection

– Cell PCH state feature keep UEs in RRC connection state, no RAB setup

2.Longer battery life for smart phone– Complex RAB setup can be avoided

from Idle state to Cell DCH state which consumes lots of control plane capacity

Cell DCH

Cell FACH

Idle

Cell/URA PCH

2-3 s inactivity

2-3 s inactivity

= RRC connected

= IDLE

RAB setup

NSN RNCs have had Cell PCH state supported for many years

(RAN1.5 onwards, 2003).


Cell/URA PCH

Other network switching between the RRC* states

Data rate

Idle

*) RRC: Radio Resource Control

30 signalingmessages

1. RRCconnReq2. RRCconnSetup 3. L1sync 4. NBAPsync 5. UEonDCH 6. RRCconnSetupComplete 7. RRC:IDT 8. RANAP:InitialUEmessag

e 9. RANAP:CommonId 10. RANAP:SMC11. RRC:SMC 12. RRC:SMComplete 13. RANAP:SMComplete 14. RANAP:RABassignment

Req 15. GTPtunnelSetup 16. RRC:RBsetup 17. RRC:RBsetupComplete 18. RANAP:RABassignment

Resp 19. RRC:MControl(HO) 20. RRC:MControl(TVM)21. UEonDCH but without u-

plane

DCH/HSPA Long inactivity timer

Time

Long inactivity timerCELL_FACH

Idle

Data rate

Time

High

Low

Zero

High

Low

Zero

Optimized state mgmt. by Nokia Siemens Networks

PCH PCH

4 signalingmessages

1. RRC:CellUpdate2. RRC:CUConfirm(C-

RNTI) 3. RRC:UMIConfirm4. UEonFACH with u-

plane

CELL_FACH inactive

150 ms

2 s


Cell/URA PCH

Other network switching between the RRC* states

Idle

*) RRC: Radio Resource Control

30 signalingmessages

1. RRCconnReq2. RRCconnSetup 3. L1sync 4. NBAPsync 5. UEonDCH 6. RRCconnSetupComplete 7. RRC:IDT 8. RANAP:InitialUEmessag

e 9. RANAP:CommonId 10. RANAP:SMC11. RRC:SMC 12. RRC:SMComplete 13. RANAP:SMComplete 14. RANAP:RABassignment

Req 15. GTPtunnelSetup 16. RRC:RBsetup 17. RRC:RBsetupComplete 18. RANAP:RABassignment

Resp 19. RRC:MControl(HO) 20. RRC:MControl(TVM)21. UEonDCH but without u-

plane

DCH/HSPA Long inactivity timer

Time

Long inactivity timerCELL_FACH

Idle

Data rate

Time

Optimized state mgmt. by Nokia Siemens Networks

PCH PCH

4 signalingmessages

1. RRC:CellUpdate2. RRC:CUConfirm(C-

RNTI) 3. RRC:UMIConfirm4. UEonFACH with u-

plane

CELL_FACH inactive

150 ms

2 s

Low device powerconsumption with Nokia Siemens Networks

Device power consumption

Device power consumption

>200 mA

>100 mA

<5 mA

>200 mA

>100 mA

<5 mA


Keep alive messagesaneb vývojáři aplikací zasahují


Always on applications create control plane load

• Many applications require always on connectivity for a good service experience.

• In order to maintain always on connectivity applications send keep-alive messages frequently.

• Keep alive message consumes control plane resources.

• Due to explosion of keep alive messages sent control plane load has sky rocketed in many WCDMA networks

Keep alive messages make RNC change UE states frequently

Keep alive messages

Cell DCH

Cell PCH / IDLE

state


Fast Dormancyaneb výrobci mobilních telefonů zasahují


0% 20% 40% 60% 80% 100%

Pohled účastníka mobilní sítě: moje priority"future of mobility" survey

Klíčové potřeby účastníka

Zlepšená životnost baterie

Fixní cena za přístup k internetu

Nižší cena za mezinárodní roaming

Voice over IP (VoIP)

Zlepšený procesní výkon zařízení

Zlepšené pokrytí v méně obydlených oblastech

Aktivní “multiple SIM“ karta ve stejném zařízení

http://www.theregister.co.uk/2007/11/19/mobile_experience/


Sudden changes in behaviour can happen

In Smart phone dominated network changes can happen overnight, caused by new firmware or killer application

For example iPhone user-friendly firmware upgrade makes upgrades unheard fast: in one network 50% of phones were upgraded within 1 week after the new firmware came available – boosting the impact of new firmware


Smart phone impact to HSPA networksWhat Went Wrong? – Why Fast Dormancy was introduced

DCH/ HSPADCH/ HSPA

FACHFACH

RRC idleRRC idle

PCHPCH

Long timer

Why is Cell PCH state needed in RNC?

1. When Cell PCH is not supported, operators are forced to use long timers to avoid frequent RAB setups

– That leads to high UE power consumption with always-on applications

2. When UE power consumption was high, some UE vendors implemented so called “Fast Dormancy” functionality which releases RRC/RAB connection when data transmission is over.

3. Frequent RAB release/setups causes problems for network (RNC) capacity.

Long timer

Only NSN implemented Cell PCH state in their RNC (2003). Many operations are using Cell PCH power saving state


A co dál ?


3GPP Solution

• 3GPP Release 8 (TS 25.331) specified, network controlled Fast Dormancy functionality clarifying the UE behavior and providing the network with information of what the UE actually wants to do, but leaving the network in charge of the UE RRC state.

• That is, the UE is not allowed to release RRC connection and move to idle state on its own without network control.

• When RNC receives SCRI from UE with a special newly introduced cause value indicating the packet data session end, the RNC can command the UE to PCH state instead of releasing RRC connection and dropping the UE to idle state.

• Not yet implemented in networks, nor UEs


A co třeba úplně nová síť LTE ?

Velmi rychlý “Link

Adaptation“(modulace dle kvality kanálu)

Krátký TTI = 1 msTransmission time

interval

Advanced Scheduling Time & Freq. (Frequency

Selective Scheduling)

TX RX

Tx RxMIMO

Channel

DL: OFDMA

UL: SC-FDMA

variabilita v šířce pásma

HARQ: Hybrid Automatic Repeat Request

64QAMModulace

1

2

21NACK ACK

Rx Buffer

Combined decoding


Děkuji

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