CSI5175 Wireless and Mobile Electronic Commerce Networks and their Applications Mao Zhang Wireless Hotspots: Current Challenges and Future Directions 1

Content Introduction An example scenario Technological challenges Alternative approaches to connectivity Conclusions 2

Introduction Today, users access the Internet at a variety of places and environments where they spend a considerable amount of time outside private networks. Wireless local area networks (WLANs) have emerged as a promising networking platform to extend network connectivity to these public places, or hotspots. WISPs have established Wi-Fi hotspots in increasing numbers at public venues. Several technological and deployment challenges remaining  Can roam anywhere?  Easy configuration?  A common way to authenticate?  Payment and billing?  Get bandwidth required?  Alternative network access technologies?  In summary, problems include authentication, security, coverage, management, location services, billing, and interoperability. 3

An example scenario A scenario to motivate the vision of widespread Wi-Fi availability and to explore the various barriers Kate needs to travel from San Diego to New York to attend a business meeting.  A presentation needs to send to colleagues before the departure  Register with the meeting venue’s Wi-Fi and get the location within the building to be guided to the meeting room  During the meeting, retrieve data from San Diego through VPN and then share with colleagues over an in-room ad hoc wireless network  Dinner time, CDMA 1xRTT card into Laptop to connect to the Internet to locate a good restaurant and get driving directions  Back to hotel, access s using the hotel Wi-Fi network 4

Technological challenges – Authenticating to the hotspot provider Sometimes, authentication is coupled with wireless-hop security where only authorized users receive network access. Authentication helps the network to establish the users’ identity, while wireless-hop security ensures data privacy for authenticated users and protection for the network. Repeat authentication at each hotspot location and the process might be configured differently. Research questions:  Ease of access and mechanism  Authentication Latency: existing hardware mechanisms such as SIM-Card based authentication?  User Identity: existing identities such as those already through other services  3 rd party authenticators? 5

Technological challenges – Wireless- hop security Security mechanisms provide data privacy to network users and also protect the network against malicious use. Current approaches include per-user authentication, authorization of authenticated users through access keys, and access control, a number of schemes achieve security and provide authentication at MAC are being deployed in W-Lans  WEP is simple to manage in environment with known users.  Port-based network access control: ports are configured to block all traffic except authentication until the user identity is established.- IEEE 802.1X 6

Technological challenges – Wireless- hop security - Continued Security challenges  Mutual Trust: e.g., implicit trust in the key distributor in WEP  Dynamic Key Management: simplified and transparent key exchange and renew  Hardware Approaches: Are there ways to provide the robustness of 802.1X through alternative hardware-based approaches?  Denial-of-Service: Current Wi-Fi networks are highly susceptible to denial-of-service (DoS) attacks  Malicious Attacks: Hotspots are a comparatively open environment for malicious users 7

Technological challenges – Network performance and QoS The ability to adequately provide capacity and coverage to handle dynamically-varying, location-dependent user load.  Understand the users’ behavior  Adapt to the changing resource availability or changing traffic characteristics which is not easy  Suggestion if adaptation is not possible Questions for research  Measurement and Modeling  Monitoring (measurements of throughput, channel contention, packet errors, etc.)  QoS Enforcement: How can MAC protocols be designed to guarantee users a fair share of the wireless bandwidth and better channel utilization 8

Technological challenges – Location and context-awareness Hotspots has the potential to make location and context- aware services more valuable and readily accessible to users Requires a number of issues to be addressed  Application scenarios  Location Privacy and Anonymity: balance  Sensor Fusion: possibility to integrate multiple location sensing technologies  Location Granularity: absolute location vs. relative location  Location to Place: the capability to translate geographic location information into a more usable form 9

Technological challenges – Pricing model 10 Wi-Fi revenues are comparatively poor, the networks are at a disadvantage compared to their cellular counterpart due to the lack of widespread coverage. But it has the potential to offer users a higher bits/sec value. Related challenges:  Subscription-based (prepaid) vs. pay-per-use model?  Central Billing Entity

Alternative approaches to connectivity - Multihop hotspots 11 Multihop access increases the network diameter and allows clients out of range of access points to receive connectivity. Challenges introduction:  Node Mobility: the number of active nodes in the ad hoc network, the network topology, and the volume of network traffic is constantly changing  Channel Interference: transmissions can cause interference at the access points, degrading effective throughput and the channel capacity.  Multiple Network Access: nodes in the multihop hotspot need: a wireless network adapter with more than one radio; or a wireless network adapter with the capability to multiplex connections from more than one network ; or more than one wireless adapter.

Alternative approaches to connectivity - Interoperation with WAN data services 12 Interoperation between cellular and hotspot networks is beneficial to both wireless carriers and hotspot operators.  Hardware support: for both services on mobile devices to migrate the connection across access technologies  Software ability through sensing to switch to the most resource-efficient mode of access  The establishment of roaming relationships and agreements between network operators for effective packet routing as users switch between them. TOGEWAnet AG offers a seamless integration of WLAN and GSM GPRS services and an integrated authentication, security, and billing over a common infrastructure:  Handoff Mechanism  Location-assisted Roaming  System Support for Handoff: Is handoff initiated at the user device or by the network?  Billing

Conclusions 13 The continuing rollout of hotspot deployment is being fueled by the growing requirement for high-speed connectivity in public areas A successful and viable hotspot business model will depend on the extent that it can provide value for all its stakeholders  End user: easy to use, economically attractive, and provides fast access  Hotspot network providers: reliable and robust third-party authenticating entity, establish peering agreements with other providers and accommodate the various resource and performance demands of the users.  Premise and building owners: establish business agreements with hotspot network providers to offer network access an everyday utility for the end user.