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

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

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

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

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)

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 Cellular IP Project

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 Design Goals

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

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 Building Blocks

MobileIP/CellularIP

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 Protocol Overview

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

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

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

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

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

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

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

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 Security

Implementation Model

Cellular IP Testbed I

Cellular IP Testbed II

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

Downlink Packet

TCP

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

cellular IP node’s throughput

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 Scalability Total population of mobiles idle active

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 (Wireless LANs today/tomorrow?)

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

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

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