Research Challenges in Mobile Networking and Computing

1. Research Challenges in Mobile Networking and Computing • Outline • Overview of Mobile Networking and Computing • Mature Research • Micro-mobility • System interworking • Open Research Topics • Security proposal • Summary Thomas F. La Porta Professor, Department of Computer Science and Engineering Penn State University

2. Global Access Lines (billion) 3 2 1 0 Wireless Cable Wireline 1958 1978 2005 Mobile Internet - Ubiquitous Communications and Computing • Wireless access to networks will soon be the most popular method • Today: 850M phone lines, 700M wireless subscribers • Wireless growth far exceeds wired growth • Internet is driving network growth • Internet users still doubling yearly • Ubiquitous wireless data has stalled… • low data rates • limited terminals • limited applications • …Mobile computing has not • lap tops are everywhere • dial-up service is pervasive • Hindered by low performance, poor connectivity, and inconvenience

3. Telephone Network Internet Telephone Network Internet Radio Radio Mobile Communications Today: Tale of 2 Networks • Cellular Telecommunications Network • Network tailored for voice – very low bandwidth • Devices not suitable for Internet and computing applications • Despite high penetration & coverage, Internet access has fizzled • The Internet – Wireless Enterprise Networks • Network tailored for best-effort data traffic – high bandwidth, no controls • Supports general computing and data networking applications • Gaining high density in hot-spots, but no ubiquitous coverage Wireless Controllers Wireless Gateways Access Router Edge Router

4. 4GRadios Core InternetBackbone 4G AirInterface Evolution to Multiservice networks 3G CellularNetworks RadioController AccessRouter UrbanNetworks • Outdoor Areas • High Mobility AggregationRouter • Broadband Distribution Networks • High Speed Pico Cells Presence EnterpriseNetworks Location AccessRouter • 802.11++ • Local Mobility • Packet Voice • High Data Rates AggregationRouter AggregationRouter Authentication HomeNetworks AccessRouter • DSL/Cable • High Speed Internet Access • Allow People to network • Self Configuring Ad HocNetworks 4GRadios • End-to-end Internet • commonmobility management and control • common transport infrastructure • common services infrastructure • Unifies various technologies (wireless, wireline, mobility)

5. Examples of Individual Multiservice Networks • Wireless Networks • 1980’s – voice services • 1990’s – voice services with very limited data capabilities (e.g., short messaging) • 2000’s – 3G multimedia networks (voice, data, multimedia) • Internet • Original use – best effort data (email, remote login, file transfers) • 1990s – some multimedia (video and audio streaming, conferencing) • 2000’s – merging of data, voice, and multimedia (Internet telephony in enterprises) • Next trend (already ongoing): merging individual networks • Impacts: • transport • control protocols • services infrastructure • management • security

6. Merging of Networks • Many challenges due to diverse applications, legacy systems, and philosophies • Voice (aka Public Switched Telephone Network) and Data (aka The Internet) • Public and Private (corporate networks) • Interworking is a big problem • service definitions, protocols, profiles, … • End result: Telephone network will get dumber, the Internet will get smarter

7. Where are we? • Seamless high-speed ubiquitous network access • new access technologies – many already exist • mobility between networks – active research area () • Internetworking • drive towards common control paradigm – controversial () • interworking between networks – islands exist () • performance – new demands on network controllers • Security • eCommerce, enterprise data, distributed computing – no one feels safe • authorization and accounting – bringing order to chaos • Intelligence and Applications • distribution between network and end devices – solutions have been vertical

8. Where are we? • Seamless high-speed ubiquitous network access • new access technologies • mobility between networks • real-time mobility – Handoffs • real-time location – Paging • Internetworking • Security • Intelligence and Applications

9. Home Agent MD Current Internet-Based Mobile Packet Networks: Mobile IP Permanent IP Address Temporary IP Address Regular routing Foreign Agent Internet Host Radio Access Networks Intranet Foreign Agent IP Tunneling • Handoffs always managed by Home Agent • high update overhead • slow handoffs • 3G UMTS Network structure is similar • uses specially defined (non-Internet) protocols for mobility

10. MD R R R R R R R R R R R R Real-Time Mobility: Domain-based Mobility Internet Domain Router Domain Router Local mobility Local mobility • Distributed control:Enhanced reliability, better scaling • Localized mobility management:Lower overhead, fast handoffs • Based on IP protocols:Independent of access network • Mobility across access networks

11. MD R R R R R R R R R R R R Real-Time Mobility: HAWAII for handoffs Internet Domain Router Domain Router Local mobility Local mobility Mobile IP • Distributed control:Enhanced reliability • recovery of lost state via Internet routing protocols • Localized mobility management:Lower overhead, fast handoffs • updates only reach routers affected by a movement • Minimized or Eliminated Tunneling:efficient routing, easy QoS • dynamic, public address assignment to mobile devices • Compatible with Mobile IP

12. BS20 HAWAII Overhead Domain Router/HA ... Router 1 Router 7 ... BS1 BS1 BS-20 2 L B r L B rn MIP = B D + B D T p 16 M 2 rn L B gr L B M-IP H = + B D B D T p 16 M 2 BD r L L B R rn B + B D D + Hawaii 16YTR p

13. HAWAII Handoff Delay: Packet Loss Audio (160B/20msec)

14. Home Router/Switch MD R R R Real-Time Location: IP Paging • Motivation • dormant mode increases battery life considerably • mobile device must be located (quickly) to deliver data • currently each network type has unique paging protocols • Challenges • limit overhead (messages) while maintaining low latency • do not impact fast-path packet forwarding • devise scaleable solution in terms of network size and administrative domains • support various paging algorithms • Basic Solution • compatible with and leveraging IP protocols • distributed control for scale and scope Determined by address Determined by Registration Determined by Paging Serving Router/Switch Network Host

15. Home Agent R R R Internet Domain Paging Area Foreign Agent Foreign Agent Foreign Agent Mobile IP Paging Area Unified Paging HA initiates page • Uniform mobility management • wireless LANs, outdoor Old FA initiates page Any router initiates page • 3 Options: • Home Agent Paging • Home agent buffers packets and initiates page to all Foreign Agents • Can be controlled by corporate network • Does not scale • Foreign Agent Paging • Last active Foreign agent buffers packets and initiate paging • Distributes load • Domain Paging • Fully distributed, very scaleable and reliable

16. R R R R R R R R R R R R IP Paging: Domain Paging Any router initiates paging Internet Domain Router Domain Router IP Paging Area • Basic Procedures • dormant MH does not send updates unless crossing Paging Area • packets sent to last known domain • any router in old path to Mobile Host may initiate paging • Characteristics • more complex: changes to routers in access network • excellent scaling: load distributed among all routers • excellent scoping: only routers in a paging area need topology information • excellent reliability: failed routers are routed around (OSPF)

17. IP Paging: Latency Results • Latency (from Stanford University Local Area traces) • Foreign Agent and Domain Paging scale best: distributed load • Domain paging slightly more scaleable (~10%): dynamic load balancing • Messaging Overhead • Domain Paging has lowest overhead: no paging related updates to Home Agent

18. Where are we? • Seamless high-speed ubiquitous network access • Internetworking • drive towards common control paradigm • Internet Control • interworking between networks • support for legacy systems (and stubborn operators!) • performance • efficiency • Security • Intelligence and Applications

19. User/mobile location management Integrate HLR/VoIP server Security control (authentication center, IP security server) functions Service profile DB management IP security server Internet Control and Interworking: Unified Mobility Manager Provide Home Location Register and Internet functionality Current HLR Cellular VoIP server Internet (VoIP) MAP / SS7 User location manager Cellular • Integrate 3 key functions of HLR & IP (VoIP) servers • mobility management • security • profile management • Support multiple interfaces • Wireless: ANSI 41, GSM / UMTS MAP • Internet: VoIP (SIP, H.323), AAA (RADIUS) Protocol Gateways Integrated User Profile Database VoIP / IP AAA / IP Internet ANSI41 / SS7 Cellular Security manager UMM

20. Core Servers Integrated user profile Unified Mobility Manager: Architecture • Core servers • Common functions across protocols • Interface via abstraction of basic services • Multiple server instances on a cluster of processors for system scalability • Interworking function between protocols: O(n) versus O(n2) complexity • Protocol gateways • Perform protocol specific controls • Facilitate new protocol introduction • Integrated user profile DB • Common database for a ‘user’ UMM CDMA 2000 PG GSM/UMTS Core Operations PG Wireless Data PG VoIP Servers PG

21. Serving Switch GW Switch BS PSTN UMM UMM HLR Serving Switch BS Internet MGW MGW UMM – Location Management Performance • 2 Basic Scenarios Considered: UMTS Network with HLR or UMM • 2 call scenarios – goal: calls travel over IP network • call from PSTN to UMTS phone (PSTN to cellular) • call from SIP phone to UMTS phone (Internet to cellular) PSTN call HLR/ UMM HLR & UMM are the same SIP Call SIP • SIP-HLR • uses PSTN for transport • inefficient Serving Switch GW Switch BS PSTN Internet • SIP-UMM • uses packet for transport • efficient • SIP-UMM (SIP e2e) • most efficient Serving Switch BS Internet

22. UMM Analytical Results • Migration to packet • short term: performance degradation from circuit/packet translation • long term: packet end-to-end improves performance

23. Research Topics: Intelligence For Network Transport • Balance between simple networks and functional networks • Ad Hoc Networks • self-configuration • very dynamic routing • Challenges: security, performance, relay networks to enhance cellular telecom • Sensor Networks • power-aware component to most functions (routing, etc.) • nodes participate in processing information • Challenges: placement, distribution of functions • Traditional Networks • multiclass admission control & charging algorithms • IP Services platforms (firewalls, web redirection, …) • Challenges: heterogeneous networks, network architecture • Heterogeneous Networks • real-time mobility between networks • Challenge: vastly different network characteristics

24. Research Topics: Intelligence for Services • Support for creativity, rapid deployment, and wide accessibility • Network architectures • separation of transport and service control • re-use across network types • Challenges: scalability, performance, reliability • Protocols • interworking across systems • legacy systems • Challenges: correct semantics, functionality mapping, software • Heterogeneous networks • access from different networks • access via different protocols • Challenges: security, flexibility, performance Services Transport

25. Research Topics: Security • Performance/Security Tradeoff • Traditional Wireless • 3G data services require network-based enhancements • Challenges – limiting performance impact, or improving performance • Ad hoc wireless, sensor networks • existing solutions are not scalable • Challenges – trade-offs of security and performance • General • end-to-end security solutions, including network, devices, OS, …

26. Performance Focused Security • Goal: Allow network-based performance enhancements in a secure environment • Specific Problem: Data performance in wireless networks is poor • network-based solutions have been proposed for 3G • caching has been proposed for ad hoc and relay networks • proposed solutions contradict security models for mobile VPNs • Sketch of solution • allow at least one intermediate “router”, positioned at the edge of the network, to view and process a portion of a secure packet • trade-off level of security for performance • Benefits • higher performance data services • access to network-based value added services with limited security trade-off

27. Security Solution for 3G: Mobile Multi-layered IPSec • Define multiple zones in a packet (as in ML-IPsec by Zhang and Singh) • each zone has an associated security association (keys, etc.) • each zone may be terminated in one or more places inside the network • Research: Initialization, Mobility, Performance • distribution of keys and initialization • maintenance of security during mobility • performance impact • implementation issues Wireless Router Corporate Network Client Network Firewall Host } Example End-to-end encryption for payload Concatenated encryption for control information

28. Ubiquitous Mobile Computing - Summary • The potential still remains… • …Hard work required - • networking: end-to-end systems issues with access and core • intelligence: distribution between device and network (dynamic & flexible) • applications and support services: retain generality • new network architectures • … with Imagination - • new ways to use mobile capabilities • perhaps extension of wireline network paradigms is wrong!!!