1. Wireless Hotspots: Current Challenges and Future Directions CNLAB at KAIST Presented by An Dong-hyeok Mobile Networks and Applications 2005

2. 1.Introduction 2.An example scenario 3.Technological challenges 4.Alternative approaches to connectivity 5.Conclusions Contents CNLAB at KAIST CALAB at KAIST 2

3. 3 Wireless Local Area Networks(WLANs) promising networking platform to extend network connectivity to wireless hotspots several technological and deployment challenges remaining for ubiquitous infrastructure ideal platform for networking in public places Introduction CNLAB at KAIST 1. Introduction long-range, wide-area coverage expensive licenses, high installation cost not meet the connectivity for large data and performance-intensive multi-media applications cellular data services

4. 4 Goal of this paper highlight the challenges posed by the vision of a global hotspot infrastructure Discuss the research problems that remain to realize Authentication, security, coverage, management, location services, billing and interoperability Introduction CNLAB at KAIST 1. Introduction

5. 5 Benefits CNLAB at KAIST scenario Send email using Wi-Fi connection in San Francisco airport Register with Wi-Fi network in New York WLAN determines location and guide to meeting room Connect to corporate network through a VPN using WLAN use the GPS using CDMA2000 Access corporate email using hotel Wi-Fi network. 2. An example scenario Question How easy is it for her to get connected when traveling from one hotspot to another? Is there one single authentication entity at all places? Is she able to get access from any location within the hotspot, or are there areas where there is not adequate coverage?

6. 6 Technology CNLAB at KAIST Formal authentication mechanism Enables users to identify themselves to the network Ease of Access Mechanism Startup Latency - SIM card: lost, malicious user User Identity: existing identity Third-Party Authenticators Research questions 3. Technological challenges 3.1 Authenticating to the Hotspot Provider

7. 7 Technology CNLAB at KAIST need of the provisioning of wireless-hop security not familiar with higher-layer security mechanisms sensitive information need to exchange securely to protect network against malicious users Wired Equivalent Privacy (WEP) in Wireless LAN standard - disadvantage: not scalable to configure keys to many users encryption algorithms are vulnerable to attack Port based network access control - more secure than WEP - disadvantage: lose validity after a short amount of time changing AP, need re-authentication MAC Layer Approaches 3. Technological challenges 3.2 Wireless-hop security

8. 8 Technology CNLAB at KAIST Network Layer Approaches CHOICE network architecture - per-packet verification - access keys are issued and verified using a centralized Authorizer- Verifier entity - more scalable because of less state maintenance in the AP Mutual Trust Simplicity-Robustness Tradeoffs Dynamic Key Management Hardware Approaches Denial-of-Service Malicious Attacks Security Challenges 3. Technological challenges 3.2 Wireless-hop security

9. 9 Technology CNLAB at KAIST Range extension Challenges Power management Wireless LAN Bridging Hardware Approaches Wireless MANs Multi-hop Hotspots Interoperability with Cellular Data Network Roaming mobile user If RF coverage is not adequate, user can easily lose connection For uninterrupted connection, hotspot operators increase the density of hotspot coverage 3. Technological challenges 3.3 Radio Frequency Range

10. 10 Technology CNLAB at KAIST Install enough APs to handle the estimated load Increase the infrastructure and maintenance cost Limit the number of APs because of interfering channel Ability of hotspot administrators handle dynamically varying, location-dependent user load Guarantee a certain minimum level of QoS 3. Technological challenges 3.4 Network Performance and QoS

11. 11 Technology CNLAB at KAIST Challenges measurement and modeling monitoring Effectively measure and monitor load at AP QoS Enforcement End-to-End QoS Dynamic resource adaptation accurate way of measuring load at each AP guarantee a minimum available resources 3. Technological challenges 3.4 Network Performance and QoS

12. 12 Technology CNLAB at KAIST Challenges Heterogeneity AP State Management Switched Wireless LANs Network capacity planning As hotspot coverage grows, APs need to be installed at various parts of network APs can be installed after a site survey 3. Technological challenges 3.5 Network Management

13. 13 Technology CNLAB at KAIST Challenges Application scenarios Location privacy and anonymity Sensor fusion Absolute Vs Relative location Interpreting location Ubiquitous availability of hotspot make location and context-aware service more valuable 3. Technological challenges 3.6 Location and Context-Awareness

14. 14 Technology CNLAB at KAIST Challenges Payment model Central billing entity - unified pricing mechanism( internet + hotspot charge ) Third-party billing contracts Usability - contract the task of infrastructure deployment, management, and support to third-party vendors. Current pricing model of Wi-Fi Users are not compelled to buy Wi-Fi connectivity 3. Technological challenges 3.7 Pricing Model

15. 15 Alternative CNLAB at KAIST Multi-hop A network where mobile nodes reach the AP over one or more hops Increase the network diameter Allow client out of range of AP to receive connectivity Node Mobility Channel Interference Power Management Multiple Network Access - one adapter & multi radio - one adapter & multiplex connection - multi adapter Multi-hop Challenge 4. Alternative Approaches to Connectivity 4.1 Multi-hop hotspots

16. 16 Alternative CNLAB at KAIST Cellular network Alternative Wi-Fi network Need hardware & software support Handoff mechanism System( device & network support ) support for handoff billing Challenge 4. Alternative Approaches to Connectivity 4.2 Interoperation with WAN Data Services

17. 17 Conclusion CNLAB at KAIST Highlight several technical and deployment-related challenges Authentication, security, coverage, network management, billing, and interoperability Provide a mechanism that is easy to use, economically attractive, and provide fast access For the end user 4. Conclusions Have a reliable and robust third-party authenticating entity Establish peering agreements with other providers for seamless and various service For the hotspot network providers Establish business agreements with hotspot network providers For the premise and building owner

18. 18 CNLAB at KAIST Any Question?