IEEE 802.21 MEDIA INDEPENDENT HANDOVER

DCN: 21-09-0118-00-0000

Title: Issues with 802.21-2008

Date Submitted: July, 2009

Presented at IEEE 802.21 Session #33

Authors or Source(s): Vivek Gupta

Abstract:

Issues with 802.21-2008

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802.21-2008 Issues

802.21 Overview

• Defines 3 services

Event Services detects events and delivers triggers from both local as well as remote interfaces (i.e. between terminal and network)

Command Service provides a set of commands for the MIH users to control handover

Information Service provides the information model and an information server to make more effective handover decisions. The mobile terminal obtains information from the repository using its current network point of attachment or the target point of attachment

Issues with 802.21-2008

• Existing and emerging cellular systems (WiMAX, 3G, 2G) already have these service concepts defined

• 802.21-2008 does not address service continuity during handovers

• 802.21-2008 just focuses on switching between radios• Network Discovery and Selection is main focus• Not viable since ND&S is not a big issue in licensed bands

• 802.21-2008 does not address Single Radio Handovers

Issues with 802.21-2008

• Event Service

• Limited utility of remote events• Refer to Aboba draft

• Individual MACs already define most of MIH Events• Link_Detected, Link_Up, Link_Down, etc.

• MIH Events don’t have any specific MAC connotation• How to implement Link_Going_Down?

• Measurement Reporting (for network-initiated handover)• MS reports its radio measurements to the network • This can be avoided since the MS can make decision for handover• So why care about MIH_Link_Parameters_Report ?

Issues with 802.21-2008

• Command Service

• MIH_MN_xxx, MIH_Net_xxx, MIH_N2N_xxx• Handle Client<>Network Co-ordination• Help with switching radios for dual radio handovers

• Not very useful in practice• Network policies typically uploaded on client devices• Client makes HO decisions based on policies• No Client<>Network co-ordination required

• MIH_MN_xxx, MIH_Net_xxx, MIH_N2N_xxx• Not required for dual radio handovers

Issues with 802.21-2008

• Information Service

• 3GPP has decided to use OMA for ANDSF• 802.11 planning to use native GAS mechanism

• 802.21 IS and RDF• Complicated and difficult to use• Value add not very clear and no SDO is adopting this!

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How to Fix 802.21-2008

MS

3GPP Network

Internet

Internet

WiMAX Network

Dual Radio Handovers

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BS ASN GW

eNB 3GPP EPC

21• Both Radios are connected to

network at the same time

• The platform needs to support simultaneous Tx/Rx

• MS uses target radio to prepare resources in target network

• Dual radio handovers lead to:• Interference when radios are in close proximity in IMT-2000 bands• Higher cost due to need for RF isolation, sharper filtering or active cancellation• Complexity in platform design

eNB: eNodeBBS: Base StationEPC: Evolved Packet CoreASN: Access Service NetworkGW: GatewayMS: Mobile Station

MS

3GPP Network

Internet

Internet

WiMAX Network

Single Radio Handovers

45BS ASN GW

eNB 3GPP EPC 21• Only one radio is connected to network at any time

• Only one radio is Tx at a time

• MS uses source radio to prepare resources in target network

• In Single radio handovers:• A L2/L3 tunnel is established between source and target network• MS uses L3 tunnel for resource reservation and authentication in target network• MS establishes Network and Security context in target network• MS powers down the source radio and powers up the target radio and does ranging on target

radio to connect to target network

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Inter-System Tunnel b/w Networks SRS

SRS: Single Radio Server

1. DL channel acquisition, MAC Synchronization (DL-MAP)

2. Initial ranging & PHY adjustment. RNG_REQ/RSP messages

3. Negotiation of basic capabilities SBC_REQ/RSP messages

4. PKMv2 MS Authentication & Authorization PKM_REQ/RSP

5. Registration (REG_REQ/RSP) Messages

6. Transport Connection Establishment DSA_REQ/RSP/ACK

7. IP Address Allocation (DHCP)

WiMAX Single Radio Handover Messages

Mobile Station

WiMAX Network

Messages over air-interface for initial network entry for WiMAX

IP Tunnel IP Tunnel IP TunnelSource

NetworkSingle Radio

Server Target

NetworkMS

N/W Entry Messages over L3 Tunnel for Single Radio HO from 3GPP to WiMAX

Dual Radio Handover Procedure

UE/ MS Source Access

Target Access

Information Repository

HA

7. Inter-system Handover Procedure (Dual/Single radio Handover)

1. Data Traffic through Source Access Network

AAA

6. Target RAT Selection and HO Decision

2. Target RAT System Information Broadcast

3. Policy and Target RAT Information Query/Response

4. Turn on Target-RAT(s) radio. Inter-RAT scanning

N/W Mobility Manager

5. Target RAT-Measurement Reporting (Optional)

8. Target RAT Network Entry Procedure

12. Data Traffic through Target Access Network

9. Switch Radio Trigger10. Mobility Protocol Binding Update

11. UE/MS IP Address Resolution

Network Discovery

& Selection

Dual Radio Handover Procedure

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802.21 Handovers

• Define Single Radio Handovers• WiMAX<>3G (Use L3 tunneling)• WiMAX<>WiFi (Use L3/L2 tunneling)• Use 802.21 MIH Protocol for tunneling MAC messages

• L2 Inter-RAT Information Broadcast• Define small subset of information that can be broadcast at L2

• Define IS at L3• Small subset of info could be used by WMF• Under discussion

• Measurements• Define a single report for WiFi-WiMAX• Use 3G Report format for 3GPP measurement reporting

• Optimized Handover between different technologies• IEEE 802.21-2008, Published in Jan-2009

• Security Signaling during Handovers • IEEE 802.21a, PAR Approved in Dec-2008

• Handovers to Broadcast Technologies• IEEE 802.21b, PAR Approved in Jan-2009

• Emergency Services in 802 networks• IEEE 802.21.1, PAR under development

• Battery Power Conservation in Multi-Radio devices• IEEE 802.21c, PAR under development

• Progression towards Media Independent Services• IEEE 802.21 Revision PAR under development

802.21 EvolutionMulti-Radio Activities in IEEE 802.21

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802.21 Next Steps

• WG already planning on doing things beyond Handovers• Multi-radio (Media independent) services

• Need to change Title and Scope of WG• Members not happy when name Media Independent Handoff appears on

cover page of subsequent specifications (ES)• Constantly asked by 802EC why are we doing things beyond handovers

• Revision PAR allows us to change Title and Scope of WG• 21-0075-01-0000