Transcript Slide 1

Wireless Hotspots: Current
Challenges and Future Directions
CSI5175 Wireless and Mobile Electronic Commerce
Networks and their Applications
Mao Zhang
2009.03.20
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Content
 Introduction
 An example scenario
 Technological challenges
 Alternative approaches to connectivity
 Conclusions
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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
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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.
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’sWi-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 emails using the hotel Wi-Fi network
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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
 3rd party authenticators?
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Technological challenges – Wirelesshop 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
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Technological challenges – Wirelesshop security - Continued
 Security challenges
 Mutual Trust: e.g., implicit trust in the key distributor inWEP
 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 802.11Wi-Fi networks are highly
susceptible to denial-of-service (DoS) attacks
 Malicious Attacks: Hotspots are a comparatively open environment for
malicious users
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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
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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
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Technological challenges – Pricing
model
 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
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Alternative approaches to connectivity Multihop hotspots
 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.
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Alternative approaches to connectivity Interoperation with WAN data services
 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: www.weroam.com
 Handoff Mechanism
 Location-assisted Roaming
 System Support for Handoff: Is handoff initiated at the user device or by the
network?
 Billing
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Conclusions
 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.
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