1. IDMP-based Fast Handoffs and Paging in IP-based Cellular Networks IEEE 3G Wireless Conference, 2001 李威廷 11/22/2001 Telcordia

2. 2 Outline Introduction IDMP Overview Fast Handoff Scheme in IDMP Paging Support in IDMP Conclusions

3. 3 Introduction (1/3) Disadvantages of Mobile IP High update latency Large global signaling load Lack of paging support These problem are also present in various non-hierarchical MIP solutions

4. 4 Introduction (2/3) The Intra-Domain Mobility Management Protocol (IDMP) is proposed recently to reduce: the latency of intra-domain location updates and the mobility signaling traffic.

5. 5 Introduction (3/3) IDMP is conceptually a two-level generalization of the Mobile IP architecture Mobility Agent (MA) provides a mobile node (MN) a domain-wide stable point of packet redirection IDMP can be combined with multiple global binding protocols With Mobile IP or SIP

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7. 7 IDMP Overview (1/3) IDMP is a multi-CoA intra-domain mobility solution Unlike HAWAII, MIP-RR or HMIPv6, IDMP is designed as a stand-alone solution for intra-domain mobility and does not assume the use of MIP for global mobility management

8. 8 IDMP Overview (2/3) Mobility Agent (MA) It is similar to a Mobile IP Regional Registration (MIP-RR) GFA It provides an MN a stable global CoA Subnet Agent (SA) It is similar to a MIP FA It provides subnet-specific mobility services

9. 9 IDMP Overview (3/3) MN obtains two concurrent CoAs: Local Care-of Address (LCoA) Similar to MIP’s care-of address Unlikely MIP, it only has local scope Global Care-of Address (GCoA) Domain-level granularity

10. Fast Handoff Scheme in IDMP

11. 11 Handoff Delay of IP-based BS (1/2) Radio-channel Establishment Delay (Δ 1 ) Establishing new radio-channel for new BS IP Subnet Configuration (Δ 2 ) SA mode:obtain an agent beacon and then request a new LCoA Co-located mode: DHCP and then LCoA Intra-domain Update Delay (Δ 3 ) MN must inform the MA of its new LCoA

12. 12 Handoff Delay of IP-based BS (2/2) Δ 1 is expected to be quite low CDMA-based soft handoff: Δ 1 is 0 Old BS is not discontinued until the connection with the new BS is established IDMP’s fast handoff process is designed to eliminate Δ 3, not eliminate Δ 2

13. 13 The Fast Handoff Procedure (1/2) Either MN or old SA generates MovementImminent message to the MA Upon reception of this message, the MA multicasts all inbound packets to the entire set of neighboring SAs Each of these SAs buffers such arriving packets After MN performs a subnet-level configuration, new SA forward all buffered packets.

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15. 15 The Fast Handoff Procedure (2/2) IDMP’s MovementImmient message does not specify the IP address of the new BS Multicast forwarding is invoked concurrently with subnet-level IP configuration phase, thereby reducing the Δ 3 The MA decides (network-controlled) the set of target BSs to which in-flight packets are multicast Only the new BS forwards arriving multicast packets to the MN

16. 16 Implementing Fast Handoff IP multicast The group membership is not dynamic PIM or DVMRP can be used to establish the multicast tree Buffer size (intra-domain update latency) * (incoming traffic rate)

17. 17 Alternative Fast Handoff Suggestions Layer-2 trigger is used to cause old FA to establish a transient tunnel to the new FA It eliminates Δ 2, but authentication is only at radio layer The MN initiate a new MIP registration with the new FA through the old FA HMIPv4/v6 Does not provide network any control over handoff process

18. Paging Support in IDMP

19. 19 Paging Operation for Idle Hosts SAs are grouped into Paging Area (PA) The MN in passive/idle mode listens FA Agent Advertisement to know which PA it belongs to MN Moving among the same PA does not update MA about its current LCoA, and not obtain a new LCoA The MA multicast a PageSolcitation packet to all the subnets associated with the MN’s current PA

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21. 21 Paging Implementation Paging Area Identifier (PAI) is used An SA can be associated with multiple PAs An MN must inform its MA when it switches from the active to the idle state, thereby activating the paging functionality at the MA

22. 22 Comparison with Alternative IP Paging Schemes IDMP does not need intermediate nodes Only SA and MA take part in the paging process  localize future upgrades Paging operations are distributed among different MAs (each serving different MNs) There is no single point of failure for the entire domain

23. 23 Conclusions (1/2) IDMP is an IP-based hierarchical mobility management and IP-based BS architecture Although the latency is higher than other schemes that assume some layer-2 coordination, the temporary buffering mechanism provides acceptable latency variation

24. 24 Conclusions (2/2) IDMP does not assume a tree-like topology and allows easy configuration of variable- sized Pas Implementation of IDMP Linux Mobile IP code (MosquitoNet Proj) MA daemon is modified from HA daemon