Building a Cellular IP Testbed

1. Javier Gomez and Andrew .T. Campbell Columbia University comet.columbia.edu/wireless support from Ericsson, Intel, Nortel and IBM Building a Cellular IP Testbed

2. Telecomm world IP world 3G, IP 3GPP, 3GPP 2 etc... Mobile IP Micro-mobility approaches Wireless IP Wireless IP views

3. 3G Wireless • Existing schemes • IMT-2000 • too many proposals • Pros • smooth mobility support • Cons • circuit model • complex/expensive infrastructure (e.g. MSCs) • strictly based on hierarchical networks

4. Mobile IP • Existing schemes • IPv4 mobility with/without route optimization • IPv6 mobility • Pros • Simple and scalable mobility solution • Cons • handoff latency and packet loss • signaling load and performance scalability • QOS

5. Micro-Mobility Schemes • New proposals for fast handoff in IETF • hierarchical foreign agents (Nokia,96) • Cellular IP (Columbia/Ericsson,98) • Hierarchical IPv6 (INRIA,98) • HAWAII (Lucent,99) • THEMA (Lucent/Nokia,99) • Other initiatives • ICEBERG (UCB/Ericsson)

6. Cellular IP Project • Project started at Columbia with Ericsson, 97 • Simple Vision: • combining the strengths of “Cellular + IP” without inheriting their weaknesses. • Cellular IP inherits cellular technology principles • but implements these around the IP paradigm • Observation • 3G and Internet fundamentally different

7. Design Goals • fast and seamless handoff • per-mobile routing soft-state • real-time location tracking - implicit paging • support for active and idle users • “passive connectivity” • single scalable protocol • simplicity • no new packet formats, encapsulation or address space • distribute mobile-aware functions (e.g., costly MSC kit) • built a foundation for QOS support

8. home agent Internet w/ Mobile IP mobile access network base station mobile Macro/micro mobility

9. Building Blocks • base station • wireless access point • routes IP packets • integrated cellular control found in MSC and BSC • IP routing replaced by Cellular IP routing • gateways • mobile IP support macro-mobility • mobiles hosts attached to the network use the IP address of the gateway as their Mobile IP COA • inside the network hosts are identified by their home addresses and packets are routed without tunneling or address conversion • mobile host

10. MobileIP/CellularIP

11. Protocol Overview • Location management & handoff are integrated with routing • data packets transmitted by a node are used to establish location and routing “soft-state” • no explicit signaling is required • uplink packets are routed to the gateway on a hop-by-hop basis • downlink packets a routed on the reverse path • idle mobiles allow state to timeout • in-band paging mechanism locates idle hosts

12. home agent E C R G Internet w/ Mobile IP R D A foreign agent F B Internet Mobile Access Network Cellular IP Mobile IP Network Model • Main Algorithms • Routing, handoff and paging

13. home agent E C R G Internet w/ Mobile IP R D R A foreign agent F B host Uplink Packets: Shortest Path

14. home agent E C R G Internet w/ Mobile IP R D R A foreign agent F B host Uplink packets: Create Location Information

15. home agent E C R G Internet w/ Mobile IP R D R A foreign agent F B host Hard Handoff • Redirected uplink packets create new downlink path • Optimal reuse of previous path

16. Semi-Soft Handoff • Delay device for synchronization home agent E C R G Internet w/ Mobile IP R D R A foreign agent F B host

17. home agent E C R G Internet w/ Mobile IP R D R A foreign agent F B host OK, Some control Messaging • Control packets are regular IP packets with no payload • They update routing entries • Discarded before reaching the internet

18. E C R G Internet w/ Mobile IP R D R A foreign agent F B host Location Management of Idle Hosts • paging mechanism • in-band signaling for paging using live data • target and broadcast technique home agent

19. Security • mobile and network have shared secret key • control messages are authenticated • Cache mappings cannot be created or modified by data packets • control packets are ICMP • control packets must contain timestamp and authentication information

20. Implementation Model

21. Cellular IP Testbed I

22. Cellular IP Testbed II

23. Hardware Cellular IP nodes/mobiles hosts: Pentium 300 MHz wired links • ethernet 10/100 Mbps wireless links • Wavelan 2 Mbps • Lucent 802.11, 2-11 Mbps • Aironet 802.11, 2-11 Mbps

24. Downlink Packet Loss @Handoff

25. TCP Throughput @Handoff

26. Scalability • Cellular IP uses per-host routes in order to support high performance handoff • does N impacts the performance? Cellular IP node 100 Mbps 100 Mbps Test mobile ttcp N

27. cellular IP node’s throughput

28. Total population of mobiles active idle Scalability The main scalability bottleneck is the overhead associated with life tracking of mobiles Cellular IP achieves scalability by: • separation of location management between idle/active mobile hosts

29. (Wireless LANs today/tomorrow?) • Today: • target coverage and high throughput as primary design goals • there is no provision for frequency reuse • power control is difficult • Tomorrow?: • data access still random (CDMA/CSMA) • there is some sort of control channel... • Improved frequency reuse/Handoff support • slotted paging = power savings

31. Summary • 3G is being redefined toward IP centric solutions • Number of new proposals on micro-mobility • New 3GIP working group • Cellular IP • is capable of combining the strengths of “Cellular and IP” approaches without inheriting their weaknesses • source code available November 99 • comet.Columbia.edu/cellularip • DEMO Cellular IP at IEEE MOMUC99

32. Cellular IP Team • Andrew T. Campbell • Javier Gomez • Sanghyo Kim • Bill Paul • Andras G. Valko (Ericsson Research) • Zoltan Turanyi (Ericsson Research) • Chieh-Yih Wan

33. Publications • Papers • "Design, Implementation and Evaluation of Cellular IP", IEEE Personal Communications, August 200.0 • Internet Draft • Cellular IP, Internet Draft, draft-ietf-mobileip-cellularip-00.txt, IETF Mobile IP Working Group Document, December 1999. • Papers, IDs and source code • comet.columbia.edu/cellularip/publications.htm