1. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 1 Defining Layer 2.5 Alan Carlton Interdigital Communications alan.carlton@interdigital.com

2. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 2 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

3. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 3 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.

4. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 4 The Cellular Mobility Model GSM1800 AP Cellular STA Network GSM900 AP EDGE AP GSM/900 AP GSM900 AP GSM900 AP FDD AP Centralized Radio Resource Management Approach Semi-Static Frequency Assignments Full Mobility Support 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

5. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 5 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)

6. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 6 The WLAN Mobility Model - Current IEEE 802.X STA Network 802.11a AP 802.11 AP 802.11b AP 802.11a AP 802.11 AP 802.16 AP 802.11n AP Dynamic Frequency Assignments Distributed Radio Resource Management Approach e.g. Gateway, Router Limited Mobility Support Radio Network

7. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 7 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

8. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 8 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 AP 802.11 AP 802.11n AP Dynamic Frequency Assignments Two Basic Options Are Considered Radio Network e.g. Gateway, Router Enhanced Mobility Support (802.21) CENTRALIZED Handover Policy Function DISTRIBUTED Handover Policy Function Option AOption B STA ONLY SYSTEM

9. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 9 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)

10. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 10 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 Handover Policy Function 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 MIB 802.11 Model

11. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 11 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 Layer 2.5 Signaling/Control Function 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

12. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 12 Typical Mobile System Architecture compared to 802.X Transparent Mode Option Physical GSM RR MAC RLC Convergence IP Mobility Protocol (MM) Physical 3G RRC MAC RLC Convergence IP Mobility Protocol (MM) Network GPRS (2G) STA3GPP (3G) STA Physical Data Link GSM 04.183GPP 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 2.5 IEEE 802.21

13. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 13 Key Protocol Functions Mobility ProtocolResource 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

14. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 14 Station FunctionNetwork/Radio Network Functions Layer 2.5 Mobility Protocol Higher Layers Physical MAC LLC U-Plane Layer 2.5 Physical MAC Link Layer Handover Policy Function Mobility Protocol Higher Layers U-Plane Lower Layers 802.11a AP 802.11a AP 802.11 AP CENTRALIZED Handover Policy Function IEEE 802.X STA Network Example: End to End Functional Configuration e.g. Gateway, Router The RHF may be defined as logical functional entity

15. doc.: IEEE 802.21-xxx Submission May 10-14, 2004 Alan Carlton, Interdigital CommunicationsSlide 15 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.