Mobility Management in Packet-based Communication Networks

1. Mobility Management in Packet-based Communication Networks Yun Won Chung Electronics and Telecommunications Research Institute E-mail: ywchung@ieee.org

2. Contents • Introduction • Mobility management in circuit-based communication networks • Mobility management in packet-based communication networks • Mobility management in all-IP networks • Further studies

3. Introduction • Mobility management • Location management • Location update (registration) • Call delivery • Handoff management • Tradeoff between location update and call delivery • Signaling load analysis • Resolution of location information (i.e., cell, location area, service area)

4. Mobility Management in Circuit-based Communication Networks

5. Location update Call delivery Location Management

6. Network Service Area in 2G Systems * source: reference [1]

7. Location Registration and Call Delivery • Centralized database architecture • Dynamic hierarchical architecture • Per-user location caching • User profile replication • Pointer forwarding • Local anchoring • Distributed database architecture • A fully distributed registration scheme • Partitioning • Database hierarchy

8. Location Update and Terminal Paging • Location update schemes • Dynamic LA management • Three dynamic update schemes • Time-based • Movement-based • Distance-based • Terminal paging schemes • Paging under delay constraints • Update and paging under delay constraints

9. Mobility Management in Packet-based Communication Networks

10. Mobile Station State • In circuit-based communication networks • MT is in idle or busy state • In packet-based communication networks • MS is in Idle, ready, or standby state in GPRS • UE is in PMM-detached, PMM-idle, cell-connected, or URA-connected state in UMTS • Cell, URA, RA, or LA is the unit area for location update • Frequency of location update and paging depend on the state of MS or UE • Effect of timer (i.e. ready timer, inactivity timer, etc.) is important

11. Network Service Area in GPRS * source: reference [1]

12. GPRS MS State Model • Idle • MS is not reachable • After attach, the MS moves to ready state • Ready • Packet transmission is possible • Cell-based location update is performed • Ready state can be sub-divided into ready(off) and ready(on) • Standby • RA-based location update is performed

13. URAs, RAs, and LAs in UMTS * source: reference [2]

14. MM state model in SGSN RRC state model in UTRAN UMTS UE State Model

15. UMTS UE MM and RRC States • MM state • PMM detached • UE is not reachable • PMM connected • Packet switched (PS) signaling connection is established • Serving RNC id is stored • Cell-connected or URA-connected • PMM idle • PS signaling connection is released • Only RA information is stored • RRC state • Idle • No RRC connection • Cell connected • Cell level location information is managed • Stays until inactivity timer expires • URA connected • URA level location information is managed

16. Research on the Analysis of MS State • Yun Won Chung, Dan Keun Sung, and A. Hamid Aghvami, “Steady State Analysis of Mobile Station State Transitions for General Packet Radio Service,” in Proc. PIMRC’2002, pp. 2029 – 2033, Lisbon, Portugal, 2002 • Yun Won Chung, Dan Keun Sung, and A. Hamid Aghvami, “Steady State Analysis of User Equipment State Transitions for Universal Mobile Telecommunications Systems,” in Proc. PIMRC’2002, pp. 2034 – 2038, Lisbon, Portugal, 2002 • Yun Won Chung and Dan Keun Sung, “Modeling and analysis of combined mobility management and implicit cell update scheme in General Packet Radio Service,” in Proc. VTC’2003 Spring, Jeju, Korea, 2003

17. Analysis of GPRS MS State • Location update & paging in GPRS • Cell in ready state • RA in standby state • Location update and paging frequencies depend on the state of MS • Tradeoff between location update and paging signaling based on the number of cells in an RA • Derivation of steady state probability of MS • Performance analysis using steady state probability

18. Modified MS State Model • Exit from Idle • Ready(off) by Attach (T12) • Exit from Ready(off) • Idle by detach (T21) • Ready(on) by packet session arrival (T23) • Standby by ready timer expiry (T24) • Exit from Ready(on) • Idle by Detach (T31) • Ready(off) by completion of session processing (T32) • Exit form Standby • Idle by Detach (T41) • Ready(off) by RA update due to movement or RA update timer expiration (T42) • Ready(on) by packet session arrival (T43)

19. Steady State Probability • Stationary probability • Steady state probability

20. Numerical Example P1: idle P2: ready(off) P3: ready(on) P4: standby

21. Analysis of UMTS UE State • Location update & paging in UMTS • Cell in cell-connected state • URA in URA-connected state • RA in PMM-idle state • Location update and paging frequencies depend on the state of UE • Derivation of steady state probability of UE • Performance analysis using steady state probability

22. Modified UE State Model • Exit from PMM detached • Cell connected (off) by attach (T12) • Exit from Cell connected (off) • PMM detached by detach (T21) • Cell connected (on) by packet session arrival (T23) • URA connected by inactivity timer expiry (T24) • Exit from Cell connected (on) • PMM detached by detach (T31) • Cell connected (off) by completion of session processing (T32) • Exit form URA connected • PMM detached by detach (T41) • Cell connected (off) by URA update (T42) • Cell connected (on) by packet session arrival (T43) • PMM idle by URA update timer expiration (T45) • Exit from PMM idle • Detach request (T51) • RA update due to movement of a UE or expiration of an RA update timer (T52) • Incoming or outgoing session arrival (T53)

23. Numerical Example P1: PMM detached P2: cell connected(off) P3: cell connected(on) P4: URA connected P5: PMM idle

24. Combined Mobility Management * source: reference [1]

25. Combined Mobility Management • Location Update • Based on LA in GSM • Based on cell or RA in GPRS • Size of LA > size of RA • Paging • Based on paging area (= LA or RA) • Combined Mobility Management • Class-A mode MS • Attached to both GSM and GPRS • Supports simultaneous operation of GPRS and GSM services • Gs interface between SGSN and MSC/VLR • Combined RA/LA update using one radio signaling message • Circuit-switched paging via SGSN to either RA or cell based on a GPRS MS state • Efficient management of GSM/GPRS MM

26. Combined Mobility Management • Implicit cell update • The location of MS is known to network if GSM MS is in busy state • How can we utilize this cell-based location information for Class-A GPRS MS state management? • After the implicit cell update, paging only one cell may be sufficient for call or packet delivery if the cell location is managed • A new MS state model • Incorporation of GSM MS state into GPRS MS state • Ready state can be sub-divided into ready(off), ready(on)-GSM, ready(on)-GPRS, ready(on)-GSM/GPRS

27. Modified MS State Model

28. Numerical Examples

29. Mobility Management in All-IP Networks

30. Micro-Mobility Protocols • Cellular IP • HAWAII • Regional registration • Hierarchical Mobile IP • Fast handoff

31. Seamoby Activities • RFC 2132: dormant mode host alerting (“IP paging”) problem statement • RFC 3154: requirements and functional architecture for an IP host alerting protocol • MH state • Active • Dormant • Functional entities • Paging agent • Tracking agent • Dormant monitoring agent

32. Motivation of IP Paging • Consider an MH, which is moving fast and is not involved in a communication • Bandwidth consumption • Processing power • Protocol states • Optimization for nodes that are currently not in a session might be taken into consideration • Entering dormant mode • Avoids frequent location update • Decreases the preciseness of the network’s knowledge about individual mobile’s location to paging areas • Dormant mode supports • saving scarce radio bandwidth • cutting superfluous location updating • reducing battery energy drainage

33. P-MIP (an Idle MN’s Movement) HA FA Reg reply MN Reg request PA1 PA2 * source: reference [3]

34. P-MIP (Page an Idle MN) HA CN MN FA data paging reg * source: reference [3]

35. Analysis of P-MIP MS State • Yun Won Chung, Dan Keun Sung, and A. Hamid Aghvami, “Steady State Analysis of P-MIP Mobility Management,” IEEE Communications Letters, June 2003 • P-MIP MS State • Active • Idle

36. Numerical Examples

37. Further Studies • Multicast accommodating host mobility • Power saving MM algorithm • Vertical handoff • Mobility support in WLAN • Network mobility • Integrated MM in heterogeneous all-IP networks

38. References • Brahim Ghribi and Luigi Logrippo, “Understanding GPRS: the GSM packet radio service,” Computer Networks, vol. 34, pp. 763-779, 2000. • Yi-Bing Lin, Yieh-Ran Haung, Yuan-Kai Chen, and Imrich Chlamtac, “Mobility management: from GPRS to UMTS,” Wireless Communications and Mobile Computing, vol. 1, pp. 339-359, 2001. • Xiaowei Zhang, “Paging in Mobile IP”, presentation material on the 4th International Workshop on Wireless Mobile Multimedia, Rome, Italy, July 2001, http://www.comet.columbia.edu/~xzhang/pmip/ • I. F. Akyildiz, et al., Mobility management in next-generation systems, Proceedings of the IEEE, vol. 87, no. 8, Aug. pp. 1347 – 1384, 1999.

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