Optimal Collaborative Access Point Association In Wireless Networks

1. Optimal Collaborative Access Point Association InWireless Networks Ouldooz Baghban KarimiSchool of Computing ScienceSimon Fraser University Jiangchuan LiuSchool of Computing ScienceSimon Fraser University Jennifer RexfordDepartment of Computer SciencePrinceton University INFOCOM 2014

2. Increase in Mobile Data Usage • Not Enough Wireless Resources • Increase in Mobile Traffic • 52% Increase over a period of a year • More offloading from cellular

3. Popularity of Wireless Local Area Networks • Dense availability of WiFi resources • Data collected in Greater Vancouver urban residential area • High availability of resources • Low availability of owned resources • Wasting excess/unused resources

4. WiFi Popularity: Real-World Example • Same Upstream Internet Service Provider • Collaboration: sharing excess WiFi Capacity • Private Access Point + Hot Spot • Optimal collaborative access point association • Centralized • Insights on Collected Data • Number of access points • Co-channel access points • Ineffective association based on highest signal quality • Interference and collision

5. Centralized Access Optimization

6. Association Problem • System Components • Users • Access Points • Local access point • Provides access to its registered devices • Host access point • Provides access to external nodes • Services quality for local users • Shared upstream provider • Opportunity • Centralized access optimization • Clustering • Reduced billing complexity • Limitations • No central control over • Deployment • Sharing limits

7. Example (a) Link Capacities (b) Non-collaborative (d) Optimal Collaborative with Concurrent Associations (c) Optimal Collaborative Association

8. Proportional Fair Access Point Association • Network Utility Maximization (NUM) Framework • Proportional Fairness [Li et al., 2008] • Maximize throughput: Proportional fair • Subject to • Time/medium sharing among co-channel access points • Time/medium sharing among users on the same access point • Limit for external users

9. PF with Sharing Results • Placement of access points based on measurement data • Increased Overall throughput • Dropped rate experienced only at a few high-rate users

10. PF with Sharing Results • Increased throughput with increase in the number of access points • Maintain collision • Concurrent connections • Maintain throughput with increased users per access point • Unused extra access points

11. PF with Sharing Results • Define cost of association • Higher external cost of association solves the dropped rate problem

12. Conclusion • Higher mobile data usage requires higher wireless resources • Dense, accessible, and inexpensive WLAN resources • Measurements to confirm • Offload from cellular networks to dense WLAN networks • Challenges & Solutions in WLANS • Collaborative access • Centralized association optimization in upstream provider • Used measurements for simulations • Up to 140% throughput increase

13. Thank you!