ABSTRACT: This contribution contains our analysis of S-RNC placement in the Evolved Network Architecture.

TITLE: S-RNC Location in the Evolved Network - Analysis

TSG-X WG31

RECOMMENDATION: Review and Adopt

Samsung Electronics grant a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner's name any Organizational Partner's standards publication even though it may include all or portions of this contribution; and at the Organizational Partner's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner's standards publication. Samsung Electronics are also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution.This document has been prepared by Samsung Electronics to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on Samsung Electronics . Samsung Electronics specifically reserves the right to amend or modify the material contained herein and to any intellectual property of Samsung Electronics other than provided in the copyright statement above.

X31-20070208-xxx

DATE: February 08, 2007

Notice

SOURCE: Samsung : Kyungjoo Grace Suh, Bill Semper, Jungsoo Jung, B.S. Bae, Veronika Kondratieva, Naehyun Lim, Daegyun Kim joo.suh@samsung.com Tel. +82-31-279-5123

Sprint Nextel : Brent Hirschman Brent.Hirschman@sprint.com Tel. +1-913-794-4271 

SK Telecom : Sean Kwak kwaksh@sktelecom.com Tel. +82-2-6100-2353

2/14

Samsung’s Position

Samsung believes the S-RNC should either be located in the AG or as a separate entity• Merits of Mobility management

– Especially paging in Idle Mode

• AG buffers the packets and initiates the paging via S-RNC – No backhaul overhead to forward data

3/14

S-RNC as a Logical Entity - Functions

Session Storage Point : Negotiated Air Interface Context• This needs to be in a central location for each session

– MS may negotiate independent Personalities with the RAN

– Each BS in the Active Set has an InUse instance, indicating the Personality in use for that BS

– Each BS must have a copy of the Session Information (Personalities, Session Signature)

Paging and Location Management• Maintain latest location information on the MS• Provide signaling for paging the MS when data arrives for it• Functions suggest central location

4/14

Interface Definitions for S-RNC as Separate Entity

S-RNC – AG Interface• AG->S-RNC

– Presence information– Paging Requests

• S-RNC->AG– Paging Responses

S-RNC – BS interface function • S-RNC->BS

– Paging Requests– Session Information Responses

• BS->S-RNC– Paging Responses– Session Information Requests– Location Updates

5/14

S-RNC Location for Paging

AG buffers data, signals S-RNC• If Data arrives at AG for idle MS

– S-RNC uses location information to page MS

– When MS is located, S-RNC signals AG; BS establishes bearer with AG, data flows

– No forwarding of data in RAN to correct BS

6/14

S-RNC Location in Network Architecture

The S-RNC is located in AG.• Easy to control paging• AG buffers the packets and initiates the paging via S-RNC

– Less backhaul overhead to forward data from BS to BS

The S-RNC as separate entity in RAN.• Central Session Information point• Data buffering in AG• Paging involves signaling with AG, no forwarding of buffered

packets through RAN (data does not come into the RAN until the MS is found)

7/14

Increased complexity in BS• Session Information retrieval more complex – one BS must

Anchor session always• Anchor BS needs to have bigger user plane buffer.

Paging is less efficient – data forwarded to Anchor BS must be forwarded to correct BS

Backhaul overhead to forward the buffered packets from anchor BS to correct BS

Limitation of SRNC in BS

8/14

Concerns about Contribution “Architecture and Handoff with S-RNC”

Contribution X31-20070201-xxx QCOM S-RNC claimed the following;• Optionally, S-RNC served as IAP (Data Anchor) when the AT

is in idle states. • Interface between S-RNC and eBS:

– Same as inter-eBS interface

– Key is distributed to the eBS

Samsung claims the following;• If S-RNC is served as data anchor, S-RNC buffers incoming

user data when MS is in idle state. Therefore, there can be backhaul overhead to forward data.

• The function of SRNC-eBS interface is paging and session fetch.

• The function of eBS-eBS interface is L2/L3 forwarding and active set managements.

9/14

Conclusion

Samsung believes the S-RNC should either be located in the AG or as a separate entity• Provides central location for Session Information Storage;

easier administration• If Paging is done by buffering data at the AG, the S-RNC can

be used to find the MS and there is no need to forward buffered data between BSs

• This makes for a less complicated BS

10/14

Appendix AAnalysis of S-RNC Location for Paging Data arrives at AG for Idle MS

• AG buffers data, signals S-RNC– S-RNC uses location information to page MS– When MS located, S-RNC signals AG; BS establishes bearer with AG,

data flows– No forwarding of data in RAN to correct BS

• Forward data to Anchor BS, allow Anchor BS to signal other BSs to page MS

– If MS has moved, data needs to be forwarded to new BS – wastes backhaul

– In flat architecture, assumes topology that allows all BSs to communicate with each other

• Forward data to S-RNC (assumes S-RNC separate entity in RAN)– S-RNC is signaling entity; this requires bearer paths between AG and S-

RNC– When MS is found, BS will still need to set up bearer to AG. Data flow

may be tricky (S-RNC forwards data to BS, eventually AG forwards data to BS)

11/14

Appendix BCase 1: Idle State- Inter AG/ Intra SRNC Handoff

AG - A

BS A-1

MS

4. MS

ID response

HA

BS A -2 BS B -1 BS B -2

SRNC B

3. MS

ID request

1. idle mode Move MS

5. MS ID assignment

AG - B

8. Bearer Setup

6. B

eare

r S

etup

7. Context Transfer

2.registration

12/14

Appendix B Case 2: Idle State- Inter AG/ Inter SRNC Handoff

SRNC A

AG - A

BS A-1

MS

5. M

S ID

res

pons

e

HA

BS A -2 BS B -1 BS B -2

SRNC B3. M

S ID

request

4. Session Transfer

1. idle mode Move MS

6. M

S ID

as

sign

men

t

AG - B

9. Bearer Setup

7. B

eare

r S

etup

8. Context Transfer

2.reg

istratio

n

13/14

Appendix B Case 3: Active State- Inter AG/ Intra SRNC Handoff

AG - A

BS A-1

MS

HA

BS A -2 BS B -1 BS B -2

SRNC B

1. Route Open Request

2. Route Open &Active set change

3. Move MS

6. MS ID Assignment

AG - B

9. Bearer Setup

7. B

eare

r S

etup

8. Context Transfer

5. MS

ID response

4. MS

ID request

14/14

Appendix BCase 4: Active State- Inter AG/ Inter SRNC Handoff

SRNC A

AG - A

BS A-1

MS

7.

MS

ID

re

spo

nse

HA

BS A -2 BS B -1 BS B -2

SRNC B

1. Route Open Request

5. M

S ID

requ

est

6. Session Transfer

3. Route Open &Active set change

4. Move MS

8. MS ID Assignment

AG - B

11. Bearer Setup

9. B

eare

r S

etup

10. Context Transfer

2. Session fetch