May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 1

doc.: IEEE 802.21-xxx

Submission

Defining Layer 2.5

Alan Carlton

Interdigital Communications

alan.carlton@interdigital.com

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 2

doc.: IEEE 802.21-xxx

Submission

Objectives

To stimulate a discussion on the preferred 802.21 Mobility Architecture

To stimulate a discussion on the scope of 802.21 To review Typical Mobile System architecture

approaches as they may pertain to the broad objectives of 802.21

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 3

doc.: IEEE 802.21-xxx

Submission

Mobile System Terminology Used in this Presentation

Two key modes exist for typical mobile systems - IDLE mode and CONNECTED mode: IDLE mode (STA) characteristics

No User service, monitoring of paging channels, available service request channels 100% of Receiver available for Downlink Measurements Background coordination, unscheduled AP/technology reselection

CONNECTED mode (STA) characteristics Active User service (e.g. a call), Handover possible Limited Receiver availability for measurements (User service takes priority) Fully Coordinated, scheduled AP/technology handover

Selection: Prior to entering IDLE mode (e.g. at Power up) the STA must perform selection in order to determine the

best AP and technology available for service

Reselection: While in IDLE mode (i.e. No User service) the STA must continuously examine neighbor AP (and different

technology AP). Upon determination of a ‘better’ AP the STA will transition over to the new AP

Handover While in CONNECTED mode (i.e. Active User Service) a handover occurs upon transition from one AP to

another AP (possibly using a different technology) offering significantly better service. In the ideal case this transition will occur without noticeable interruption of the Active User Service.

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 4

doc.: IEEE 802.21-xxx

Submission

The Cellular Mobility Model

GSM1800

AP

Cellular STA

Network

GSM900

AP

EDGE

AP

GSM/900

AP

GSM900

APGSM900

AP

FDD

AP

Centralized Radio Resource Management Approach

Semi-Static Frequency Assignments

Ful

l Mob

ility

Sup

port

Handover Policy

Function

e.g. GSM Base Station

e.g. FDD Node B

e.g. 2G MS, 3G UE

e.g. 2G BSC, 3G RNC

Radio Network

e.g. Switch, Server

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 5

doc.: IEEE 802.21-xxx

Submission

The Cellular Mobility Model (Continued) Radio Network Characterization:

Centralized RRM approach (Semi-Static Frequency assignments in each AP) Some Radio Planning Required

IDLE Mode Operation: Intra-technology (e.g. GSM to GSM)

AP Selection/Reselection decision made in STA supported by System information broadcast by the Handover Policy function (Policy defined in the Handover Policy function)

Inter-technology (e.g. GSM to FDD/WCDMA) AP Selection/Reselection decision made in STA supported by System information broadcast at the Handover

Policy function (Policy defined in the Handover Policy function)

CONNECTED Mode Operation: Intra-technology

AP handover decision made in the Handover Controller function supported by measurements made by the STA and sent to the Handover Policy function via L3 signaling (Policy defined in the Handover Policy function)

Inter-technology AP handover decision made in the Handover Policy function supported by measurements made by the STA

and sent to the Handover Policy function via L3 signaling (Policy defined in the Handover Policy function)

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 6

doc.: IEEE 802.21-xxx

Submission

The WLAN Mobility Model - Current

IEEE 802.X STA

Network

802.11a

AP802.11

AP

802.11b

AP802.11a

AP

802.11

AP

802.16

AP

802.11n

AP

iBook

Dynamic Frequency Assignments

Distributed Radio Resource Management Approach

e.g. Gateway, Router

Lim

ited

Mob

ility

Sup

port

Radio Network

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 7

doc.: IEEE 802.21-xxx

Submission

The WLAN Mobility Model (Continued) Radio Network Characterization:

Distributed RRM approach (Dynamic Frequency assignments in each AP) Radio Planning Not Required

IDLE Mode Operation: Intra-technology (e.g. 802.11a to 802.11a)

AP Selection/Reselection decision made autonomously in STA (Policy defined in the STA) Inter-technology (e.g. 802.11 to 802.16)

SELECTION/RESELECTION NOT STANDARDIZED – SCOPE OF 802.21 CONNECTED Mode Operation:

Intra-technology

HANDOVER NOT STANDARDIZED – SCOPE OF 802.21 Inter-technology

HANDOVER NOT STANDARDIZED – SCOPE OF 802.21

General Scope of 802.21

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 8

doc.: IEEE 802.21-xxx

Submission

The WLAN Mobility Model – Enhanced (802.21)

802.11a

AP

IEEE 802.X STA

Network

802.11

AP

802.16

AP

802.11b

AP

802.11a

AP802.11

AP

802.11n

AP

iBook

Dynamic Frequency Assignments

Two Basic Options Are Considered

Radio Network

e.g. Gateway, Router

Enh

ance

d M

obili

ty S

uppo

rt (

802.

21)

CENTRALIZED Handover

Policy Function

DISTRIBUTED Handover

Policy Function

Option A Option B

ST

A O

NL

Y SY

ST

EM

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 9

doc.: IEEE 802.21-xxx

Submission

Option A & Option B Definition IDLE Mode Operation:

Intra-technology (e.g. 802.11a to 802.11a) AP Selection/Reselection decision made autonomously in STA (Policy defined in the STA)

Inter-technology (e.g. 802.11 to 802.16) [SCOPE OF 802.21] Option A: AP Selection/Reselection decision made autonomously in STA (Policy defined in the STA)

Option B: AP Selection/Reselection decision made in STA supported by System information broadcast at the Handover Policy function level (Policy defined in the Handover Policy Function)

CONNECTED Mode Operation: Intra-technology [SCOPE OF 802.21]

Option A: AP handover decision made autonomously in STA (Policy defined in the STA)

Option B: AP handover decision made in the Handover Policy function supported by measurements made by the STA and sent to the Handover Policy function via new signaling mechanisms (Policy defined in the Handover Policy Function)

Inter-technology [SCOPE OF 802.21] Option A: AP handover decision made autonomously in the STA (Policy defined in the STA)

Option B: AP handover decision made in the Handover Policy function supported by measurements made by the STA and sent to the Handover Policy function via new signaling mechanisms (Policy defined in the Handover Policy Function)

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 10

doc.: IEEE 802.21-xxx

Submission

Option A: DISTRIBUTED Handover Policy Function

Option A Provides a Very Limited Mobility Solution

MAC Sublayer

MAC Sublayer

ME

Physical Sublayer

ME

PLCP Sublayer

PMD Sublayer H

and

ov

er P

oli

cy

Fu

nct

ion

STA Functional Architecture Concept

Intra/Inter Technology Reselection decision made autonomously by the STA Adequate but sub-optimal solution

Intra/Inter Technology Handover decision made autonomously by the STA Slow Handover Solution /Really just an

extension of Reselection and would be characterized as such in a typical Mobile system

Break and then Make strategy (Resource availability not guaranteed)

Adequate solution for non real-time services

Unacceptable solution for real time services (such as voice)

Poorly scaleable solution

Local MIB802.11 Model

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 11

doc.: IEEE 802.21-xxx

Submission

Option B: CENTRALIZED Handover Policy Function

Option B Provides a Full Mobility Solution – Typical Mobile System Architecture Approach

MAC Sublayer

MAC Sublayer

ME

Physical Sublayer

ME

PLCP Sublayer

PMD Sublayer L

ayer

2.5

Sig

nal

ing

/Co

ntr

ol

Fu

nct

ion

System HPF

STA Functional Architecture Concept

Measurements

System Info

Handover Intra/Inter Technology Reselection decision supported by System Information Optimal solution

Intra/Inter Technology Handover decision coordinated by RPF and supported by measurement reports and System signaling Fast Handover Solution Make and then Break strategy (Resource

availability is guaranteed) Adequate solution for non real-time

services Acceptable solution for real time services

(such as voice) Easily scaleable solution

802.11 Model

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 12

doc.: IEEE 802.21-xxx

Submission

Typical Mobile System Architecture compared to 802.X

Transparent Mode Option

Transparent Mode Option

Physical

GSM RR

MAC

RLC

Convergence

IPMobility Protocol (MM)

Physical

3G RRC

MAC

RLC

Convergence

IPMobility Protocol (MM)

Net

wo

rk

GPRS (2G) STA 3GPP (3G) STA

Ph

ysic

alD

ata

Lin

k

GSM 04.18 3GPP 25.331

User Plane

Control Plane

User Plane

Control Plane

In a Full Mobility Solution Layer 2.5 is a key enabler

IEEE 802.xx STA

e.g. Mobile IP

Physical

MAC

LLC

Convergence

IP

IEEE 802.3,11,16…

IEEE 802.2

Transparent Mode Option

Layer 2.5IEEE 802.21

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 13

doc.: IEEE 802.21-xxx

Submission

Key Protocol Functions

Mobility Protocol Resource Control Protocol(e.g. GSM-MM/MAP, Mobile IP…) (e.g. GSM-RR, 3GPP RRC, L2.5?)

System Information Termination (or Paging) Cell Selection/Reselection Establishment Release Measurement Reporting Power Control Handover at Radio Level

Discovery Registration Tunneling Termination (or Paging) Handover at Network Level Security

Both Functions are required in order to support a Full Mobility Solution

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 14

doc.: IEEE 802.21-xxx

Submission

Station Function Network/Radio Network Functions

Layer 2.5

Mobility Protocol

Higher Layers

Physical

MAC

LLC

U-P

lan

e

Layer 2.5

Physical

MAC

Link Layer

Handover Policy

Function

Mobility Protocol

Higher Layers

U-P

lan

e

Lower LayersLower Layers

802.11a

AP

802.11a

AP

802.11

AP

CENTRALIZED Handover Policy

Function

IEEE 802.X STA

iBook

Network

Example: End to End Functional Configuration

e.g. Gateway, Router

The RHF may be defined as logical functional entity

May 10-14, 2004

Alan Carlton, Interdigital Communications

Slide 15

doc.: IEEE 802.21-xxx

Submission

Conclusions The Option B architecture with a centralized Handover Policy Function would seem to

be the most promising approach and is recommended. In order to provide a full mobility solution both Radio Mobility (e.g. GSM RR) and

Network Mobility (e.g. Mobile IP) protocol functionality is required in the system. Layer 2.5 is a key enabler in a full mobility solution. In order to support the Option B Architecture 802.21 should define a Layer 2.5

Signaling and Control Protocol with some similar properties to RR style protocols currently used in typical Mobile systems.

The Handover Policy Function may be defined as a logical entity. It is not necessary to define any restrictions in the Standard on its location in a physical implementation though some recommendations may be made if valuable.

The Option B architecture closely maps to well proved typical Mobility System architectures and will simplify future advanced interworking scenarios unanticipated at this time (e.g. tightly coupled handover).

The Centralized Handover Policy Functional architecture may be easily extended to support Wireless to Wired interworking scenarios e.g. the Handover policy upon connecting a Wireless device to a Wireline system may be automatic handover.