1. Policy-Based QoS Management Architecture in an Integrated UMTS and WLAN Environment 莊勝超　洪志宗　張永伸　蘇芳生 IEEE Communications Magazine November 2003 p.118

2. Outline • Introduction • Policy-Based QoS architecture in WLAN Networks • Policy-Based QoS management in an integrated environment (Scenarios) • Conclusion

3. Introduction • Why integrate WLAN and UMTS network? • UMTS ’s bandwidth is not sufficient for public wireless broadband service • WLAN acts as an complementary broadband access in hotspots • What is the benefit for integrating WLAN and UMTS network? • High bandwidth for hotspot and seamless coverage for other place

4. Introduction (cont.) • QoS (Quality of Service) • QoS is an industry-wide initiative to provide preferential treatment to certain subsets of data, enabling that data to traverse the Internet or intranet with higher quality transmission service • Policy-based • Policy-based management is an administrative approach that is used to simplify the management of a given endeavor by establishing policies to deal with situations that are likely to occur

5. Introduction (cont.) • PDF/PDP (Policy Decision Function/Point) • MPDF (Master PDF) • PEP (Policy Enforcement Point) • COPS (Common Open Policy Service)

6. Policy-based QoS architecture in WLAN (cont.) • Tightly Coupled • WLAN devices is treated as if they are normal UMTS UE (User Equipment) • PDF can enforce the network-level policies at the WR directly • PDF is reused (WLAN and UMTS) • No effect on the 3GPP access control and billing/charging entities

7. Policy-based QoS architecture in WLAN (cont.) • Loosely Coupled • WLAN is considered as a peer UMTS network • Constitutes a distinct policy domain with its own PDF (WPDF) • Standalone WPDF to perform service-level policy control for the WLAN domain • Is not expected to affect the access control and billing/charging reference model

8. Policy-based QoS architecture in WLAN

9. QoS Management in an integrated UMTS and WLAN environment • One operator controls the UMTS network and WLANS • Different UMTS operators share a WLAN • An independent WLAN is interconnected to a UMTS operator’s network

10. Scenario 1: UMTS and WLAN under one operator

11. Scenario 1

12. Scenario 1 (cont.) • When encountered a conflict • WPDF asks the MPDF to resolve the policy conflict (by sending QoS parameters) • MPDF resolves conflicts by creating new network-level policies based on the network-wide policies • After resolved the conflict • MPDF validate new policy with UMTS’ PDF • Sends back new policy to WPDF and also writes to policy repository

13. Scenario 2: A WLAN network shared by multiple operators

14. Scenario 2 (cont.) • WPDF is a child node in the policy hierarchies of operators A’s and B’s networks • It is serving two MPDFs that are peers.

15. Scenario 2 (cont.) • It is inevitable that the WPDF will encounter conflict policies provided by different MPDFs • Way of resolving conflicts • MPDFs soles responsible for negotiating new policies that will replace the old policies • Additional policies known as overriding policies are preset in the WPDF and are used to resolve the conflicting policies

16. The reason why solution 2 is better • Operators of MPDFs does not have to worry about policies in shared WLAN infrastructure • New WLAN domains can easily be added without affecting policies implemented by the individual MPDFs

17. Scenario 2 (cont.)

18. Scenario 2 (cont.) • When encountered conflicts • First, WPDF must verify that they do not conflict with policies installed by another MPDF • Second, WPDF asks the MPDF to resolve the conflicts by sending QoS parameters

19. Scenario 2 (cont.) • If there is a conflict between QoS parameters and policies installed by another MPDF • WPDF resolve the conflict by applying overriding policies (modify QoS parameters) • Send overriding policies to MPDF • After MPDF creating new policy • MPDF validates them with PDF of the UMTS domain on the data path of the session

20. Scenario 3: Customers’s WLAN Interconnected to an operator’s UMTS network

21. Scenario 3 (cont.) • This model allows the UMTS operator to provide wide-area mobile services to customers that have their own WLAN infrastructure • WPDF in the WLAN domain is a peer of the MPDF in the UMTS network • Network-level policies is determined by service level specifications (SLSs)

22. Scenario 3 (cont.) • There are dynamic and static service requirements • Static service can be directly translated into enforceable netowrk level policies • Dynamic services are dependent on the state of the UMTS/WLAN network • Dynamic services can only be translated into network-level policies after negotiating with the connecting networks

23. Scenario 3 (cont.)

24. Scenario 3 (cont.) • When encounter a network state change • WLAN send revised SLS parameter encapsulated in COPS) to IPA2 • IPA2 check if the requested SLS parameters is supportable • If supportable, return a positive COPS message • If not supportable, forward SLS parameters to IPA3 after translate into network-level policies for verification purpose • If translate failed, return negative COPS decision message to WLAN

25. Scenario 3 (cont.) • Continued • IPA3 will repeat IPA2's action • If updated SLS parameters can be implemented, IPA3 will return a positive COPS message, or it will return a negative COPS message to IPA2 • After IPA2 received positive COPS message, it will also return a positive COPS message to WLAN

26. Scenario 3 (cont.) • If WPDF receieved a negative COPS message • Modify SLS parameters and resend it • Retry until a upper limit

27. Conclusion • Todos • Standarlize COPS message • Enhance security of communications channel between the interconnected policy entities • Quicken the process of policy negotiation in peering architecture • Problem • Depth of the hierarchical architecture affects the policy provisioning time in an operator's network