wireless hotspots: current challenges and future directions cnlab at kaist presented by an...

Wireless Hotspots:

Current Challenges and Future Directions

CNLAB at KAIST

Presented by An Dong-hyeok

Mobile Networks and Applications 2005

1. Introduction

2. An example scenario

3. Technological challenges

4. Alternative approaches to connectivity

5. Conclusions

Contents

CNLAB at KAISTCALAB at KAIST

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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

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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

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1. Introduction

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Benefits

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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?

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Technology

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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


3.1 Authenticating to the Hotspot Provider

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Technology

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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


3.2 Wireless-hop security

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Technology

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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


3.2 Wireless-hop security

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Technology

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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


3.3 Radio Frequency Range

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Technology

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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


3.4 Network Performance and QoS

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Technology

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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


3.4 Network Performance and QoS

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Technology

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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


3.5 Network Management

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Technology

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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


3.6 Location and Context-Awareness

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Technology

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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


3.7 Pricing Model

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Alternative

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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

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Alternative

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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

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Conclusion

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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

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