Architectures to support Offloading and Multi Connection APCC/ATNAC 2010 Version 0.1 Prasan de Silva...

Architectures to support Offloading and Multi Connection

APCC/ATNAC 2010

Version 0.1

Prasan de SilvaEnterprise Architect (Wireless & Convergence)Group TechnologyTelecom (NZ) Corporation

2© Copyright Telecom Corporation of New Zealand 2010. All rights reserved.

Disclaimer

The views presented in this presentation are not reflective of Telecom’s technology roadmap. The author is presenting his own research views on this emerging area

within the industry.


Contents

1. Definition and Problem Space

2. Typical Use Cases for Offload and Multi Connection

3. Survey of Technology Options

4. Recap on UMTS Architecture

5. Recap on LTE Architecture

6. Femto Cell Architecture (3GPP Rel 8)

7. Femto Cell Architecture (3GPP Rel 10)

8. Local IP Access (LIPA) (3GPP Rel 10)

9. Integrated WLAN (I-WLAN) (3GPP Rel 7)

10.IP Flow Mobility (3GPP Rel 10)

11.ITU-T SG13 Multi Connection Architecture

12.Comparison of Techniques (intra-3GPP)

13.Comparison of Techniques (inter-3GPP)

14.A Target Architecture to Support Offload and Multi Connection


Definition and Problem Space

• A mobile network is composed of finite resources which must be used optimally to maximise KPI’s such as accessibility, retainability and reduce cost per bit to serve.

• While it is expected that networks scale to meet traffic demands, the key constraint is available spectrum.

• Accepted (or traditional) practice for network expansion follows a pattern such as:

• radio access network is optimised (e.g. antenna tilts, power budgets, interference mitigation etc)• sectorisation techniques can be employed (omni to 2/3sector to 6 sector etc)• additional carriers can be added (if spectrum is available)• coverage footprints can be reduced and new sites deployed• hierarchical cells structures can be introduced such as micro/pico cells to offload the macro carriers

• .The industry is witnessing unprecedented growth in demand for capacity – primarily driven by data devices.

• Reports such as Credit Sussie [*] claim that even if an extra 300MHz of required spectrum planned for allocation by the FCC in 2015 happens, 65% of the projected growth will still not be met.

• This suggests that traditional methods of offloading alone will not suffice and other techniques will be needed to meet the demand from mobile devices.

• This presentation focuses on state of the art mechanisms under study for offload and multi-connection techniques.

• An underlying premise behind offload strategies is that the cost to serve of the recipient network or resource must be substantially lower than the primary network.

• The presentation draws on current output from 3GPP and ITU T Study Group 13

*Telecom Industry Themes – Profiting From the Spectrum Crisis, 24 May 2010


Typical Use Cases for Offload and MC

Session TransferralBandwidth Aggregation

Resiliency – path diversity Concurrent Applications

Ref: ITU-T Y.2000 Supplement 9


Survey of Technology Options

Offload & Multi Connection

Offload

Intra-RAT(e.g. UMTS 850Mhz to

UMTS 2100 MHz)

Inter-RAT(e.g. UMTS to GSM)

Intra-3GPP

Femto(Home NodeB)

Inter-3GPP

I-WLANLocal IP Access

Hierarchical Cell Structures(e.g. macro to micro or

pico cells)

IP Flow Mobility

ITU-T SG13Multi Connection


Recap on UMTS Architecture

MSC

RNC

Radio Access Network

Packet Switched Core

Data Services(e.g. Internet)

Public Switched Telephone Network

(PSTN)

User Equipment

Node B

MGW

SGSN GGSN

IuB

Gn

IuPS

IuCS

Gi

HLR

Gr

D

Mc

IuB

Nb

Nc

Circuit Switched Core

Ref: 3GPP TS23.002 v9.1.0


Recap on LTE Architecture

Ref: 3GPP TS23.002 v9.1.0

SGW

MME

P-GW

PCRF

Control Plane

eNode B

S1-U

Gx

HSSS6a

S11 X2

S5

SGi

S1-MME

(D) eNode B

LTE UE

Data Services (e.g. Internet)

S10

EPCE-UTRANUE

EPS

User Plane

LTE RANEPC

LTE-Uu

Un

RN


Femto Cell Architecture (3GPP Rel 8)

• The femtocell, or Home NodeB (HNB as defined by 3GPP) combines the NodeB and RNC functions.

• The HNB interconnects to the Home NodeB Gateway (HN GW) via the newly defined IuH interface.

• The IuH interface performs pseudo registration functions of HNB and UE’s as well as tunnelling of Non-Access Stratum (NAS) signalling to the core network.

• The femtocell interconnects to the Mobile core network via the standard IuCS/PS interfaces, through the HNB GW function.

• Mobility procedures employ existing mechanisms such as idle mode cell reselection through neighbour list advertisements, PLMN IDs, Closed Subsriber Group IDs, LAC, RAC, SAC and Primary Scrambling Code parameters sent via standard System Information Blocks.

• With overlapping coverage, connected mode handoff is also supported.

Ref: 3GPP TS25.467 v9.1.0



Ref: 3GPP TS25.467 v9.1.0

UTRAN

Broadband Network

HNB

NodeB

RNC

HNB GTY

IuB

IuH

Radio Access Network Core Network

MSC

HLR

SGSN GGSN

IuCS

IuPS

IuPS

IuCS

Gn GiPacket Data Network

D

Gr



L2/L1

Transport IP

Tunnel Layer IPSec

SCTP SCTP

RF

MAC

RLC

L2/L1

Transport IP

IP IP

SCTP

SCCP/ M3UA

HNB HNB GW

L2/L1

MSC

Uu

IuCS

UE

CS Control Plane (24.008)

IP

NAS

RUA RUA

RRC RANAP RANAP R ANAP

SCCP/M3UA

Tunnel Layer IPSec

HNBAP HNBAP

IuH

RF

MAC

RLC

RRC

NAS

L2/L1

Ref: 3GPP TS25.467 v9.1.0

• A key concern with regards to Femto is interoperability – and the key interface is the IuH

• There are two key protocols operating over IuH, namely, RANAP User Adaptation (RUA) and Home NodeB Application Part (HNBAP).

• RUA implies that every HNB acts like an RNC to the core from a signalling perspective.

• HNBAP is the means by which all HNB management and registrations occur.

• Can an operator safely mix and match vendor products for HNB and HNB GW – and if not what are the consequences?



• 3GPP Release 10 is studying Femto architectures which integrate directly into an operator IMS core.

• This approach allows offloading CS traffic from both the UTRAN and mobile CS core.

• The most promising option is where the IMS Centralised Services (ICS) architecture is re-used (this effectively implies that H2=I2)

• The key item to this approach is that the HNB GW natively converts UMTS layer 3 NAS signalling to SIP. The HNB GW therefore acts like an MSC enhanced for ICS.

• Native protocol mapping by the HNB GW avoids the need to do conversions (like NAS<->BICC) which can lead to service transparency issues.

Ref: 3GPP TR23.832 v10.0.0



Ref: 3GPP TR23.832 v10.0.0

UTRAN

Broadband Network

HNB

NodeB

RNC

HNB GTY

IuB

IuH

Radio Access Network

Core Network

MSC

HLR

SGSN GGSN

Gn GiPacket Data Network

D

Gr

P-CSCF I-CSCF

S-CSCF

MGCF/MGW

IMS Core Network

HSS

H2 Mw Mw

Mg

Cx

IuPSIuCS

RTP


Local IP Access (LIPA)

• Local IP Access (LIPA) is defined as the capability that allows the UE to request that all the packet data traffic exits the mobile architecture at the base station node (i.e. eNB).

• The offload in this case is to the customers LAN network (e.g. their xDSL based broadband connection).

• In this scheme the user plane packet data session does not utilise the mobile RAN, backhaul or core network. The control plane, however continues to use the mobile infrastructure.

• The enhancement needed in the HNB end is the support of a local gateway function which acts as the egress for the packet data user plane (i.e. a GGSN or SGW/P-GW function).

• A subset of this approach is called Selected IP Traffic Offload (SIPTO).

Ref: 3GPP TR23.829 v1.2.0


Local IP Access (LIPA)

Ref: 3GPP TR23.829 v1.2.0

E-UTRAN

Broadband Network

H(e)NB

eNodeB

H(e)NB GTY


MME

HSS

SGW P-GW

S1-U

S1-MME

S5 SGiPacket Data Network

S6a

S1-MME

S1-U

L-GW

To xDSL Network

S11


Integrated WLAN (I-WLAN)

• I-WLAN allows a 3GPP operator to extend the cellular subscription to the WLAN domain for seamless service authentication and authorisation but not seamless handoff to/from 3GPP network.

• I-WLAN reuses the USIM based credentials to authenticate WiFi access, thus offloading the entire mobile RAN and PS core.

• I-WLAN introduces a new Packet Data Gateway (PDG) node which acts as an operator hosted access router and security gateway.

• The PDG interworks with the operators AAA infrastructure, which in turn links to the HSS/HLR/AuC so that EAP-SIM or EAP-AKA schemes could be used in the WLAN domain. Thus the reuse of customers (U)SIM based credentials.

Ref: 3GPP TS23.234 v9.0.0


Integrated WLAN (I-WLAN)

Ref: 3GPP TS23.234 v9.0.0

UTRAN

Broadband Network

WiFi AP

NodeB

RNCIuB

Wu


MSC

HLR

SGSN GGSN

IuCS

IuPS

AAA

Gn

GiPacket Data Network

D

Gr

D’

Wm

Wi

PDG


IP Flow Mobility

• IP flow mobility and seamless WLAN offload has been standardised in Release 10 TS23.261.

• The standard allows a WiFi/Cellular device to split traffic between the two access networks simultaneously in a coordinated manner.

• By coordinating traffic between the networks, it is possible to offload some or all sessions from the cellular network.

• For example, a UE involved in a videoconference may send real time voice component over UMTS and the high bandwidth video over WLAN.

• The Evolved Packet Core (EPC) has provided the missing pieces of flow mobility for non-3GPP access integration (e.g. for I-WLAN, WiMAX). Hence IP flows can be anchored in the common core and bearer plane tunnels moved across the IP-CANs as needed with seamless continuity of sessions.

• The key enabler being derivatives of Mobile IP - specifically DSMIPv6, P-MIP, and C-MIP.

Ref: 3GPP TS23.261 v10.0.0


IP Flow Mobility

Ref: 3GPP TS23.402 v10.0.0

E-UTRAN

WLAN

AP

eNodeB


MME

HSS

SGW

P-GW

S5 SGiPacket Data Network

S6a

S1-MME

S1-U

S11

ePDG

AAA

S2a,b,c

SWm

SWx


ITU-T SG13 Multi Connection Architecture

Multi- connection Transport Control Function

Service Stratum

Transport Stratum

Transport Functions

Transport Control Functions

Service Control and Content Delivery Functions

External Applications

Application Support Functions and Service Support Functions

Service Control Functions

Content Delivery Functions

Network Attachment and Control Functions

Resource and

Admission control

Functions

Mobility Management and Control Functions

End-User

Functions

Functions from Other

Networks

Functionsfrom other

Service Providers

ANI

NNI

SNI

UNI

Service User Profiles

Transport User Profiles

IdM Function

s

Man

agem

ent

Fun

ctio

ns

Control

Media

Management

IdM

Access Point 1

User Equipme

nt

Multi- connection Application

Access Point n

Multi-connection

Coordination Funciton

Multi- connection Access Control

Function

Multi- connection Registration Function

Multi- connection Service Control Function

Multi- connection Media Control

Function

Multi- connection Access Control

Function

• Multi Connection is a new and promising area under study in ITU-T SG13.

• The functionality is not being addressed in other SDO’s. Though 3GPP’s new item on Inter-UE Transfer (or IUT) has some overlap.

• The diagram below shows the work-in-progress mapping to the NGN reference architecture, highlighting new functional entities which need to be defined.

Ref: ITU-T SG13 Y.MC_ARCH (Draft)


Comparison of Techniques ( intra-3GPP)

Offload Technique

RAN Offload? Core Offload? Standard Complete?

Device Impact?

Network Impact?

Ideal Reference

Case

Yes Yes Yes No No

Hierarchical Cells

Yes for congested macro sector

No Yes No No

Inter-band Yes for congested freq. band

No Yes No (for multi band UE)

No

Inter-RAT Yes (e.g. GERAN to UTRAN)

No Yes No (for multi RAT UE)

No

Femto (Rel8)

Yes No Yes Yes for CSG support

Yes – new nodes needed

Femto (Rel10)

Yes Yes for IMS alternate

No No Yes – new nodes needed

LIPA Yes Partial (user plane offloaded)

No Yes - LTE device needed

Yes - Enhancements

to HeNB needed

SIPTO No Yes (partial) No No Yes - Direct tunnel for UMTS and new L-GW

for LTE


Comparison of Techniques (inter-3GPP)

Offload Technique

RAN Offload? Core Offload? Standard Complete?

Device Impact?

Network Impact?

I-WLAN Yes Yes Yes Yes – EAP schemes

Yes – new network

node/AAA integration

IP Flow Mobility

Yes – entire session offload or partial session offload

No Yes Yes Yes

GAN Yes No Yes (for GSM) Yes Yes

ITU-T MC Yes – similar to IP flow mobility

No No Yes - TBD Yes - TBD


A Target Architecture to Support Offload and MC

HNB GW

RNC

H(e)NBGW

(e)PDG

MSC

SGSN

SGW

MME

HLR

HSS

AAA

PCRF

P-GW

*ANDSF

S3

S11

S1-U

S1-U

S1-C

S1-C

X2

S4

SGs

IuPS

IuCS

IuPS

IuCS

D

Gr

Gs Wx

SWx

Gx

S6a

S1-C/U

IuB

IuB

NodeB(macro)

NodeB(micro)

H(e)NB

IuH

HNB

eNodeB

AP

S14

Home NodeB Network

UTRAN

Home eNodeB Network

E-UTRAN

Non-3GPP Networks

PDN

UMTS Core

Evolved Packet Core (EPC)

S5 SGi

S2a, S2b, S2c

S6d

AuC

H

S6b

Gxa

SWm

L-GGSN

L-GW

(D)eNB

RNUn


Thank you for listening

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