1. A Congestion Pricing User Study Using a 802.11a Wireless LAN Jimmy Shih, Randy Katz, Anthony Joseph

2. Problem Statement How to allocate wireless bandwidth? Insufficient bandwidth during peaks. Use prices to encourage some users to conserve bandwidth during congestion. E.g. Encourage heavy users to conserve bandwidth to support more light users. Congestion pricing:vary prices according to load. Allocate scarce bandwidth. Save over-provisioning. Provide guaranteed service. Goals: Measure effectiveness of using congestion pricing. Understand user acceptance to changing prices.

3. State-of-the-Art Proposals of different congestion pricing mechanisms. Senders pay at each congested point. Senders pay to neighboring domains. Receivers pay for received congested packets. Simulations: Assume particular user model. Show that congestion pricing potentially can be better. Little actual experimentation. Need to quantify tradeoffs of congestion pricing. Need to demonstrate user acceptance.

4. Methodology Combination of user experiments and simulations to quantify effectiveness of congestion pricing for wireless bandwidth. 1.Experiments for understanding acceptance and reactions to price changes. 2.Simulations for understanding management of congestion pricing under high loads. 3.Combining user experiments with simulations to verify users’ reactions and tradeoffs.

5. Prototype Internet WLAN Internet Packeteer PacketShaper Web Server Access Router 1 2 3 1:Control: TCP connection. 2:Control: web connections. 3:Data

6. User Interface Rate-limit each IP address to certain bandwidth. Give each user some free tokens a week. User needs more bandwidth, goes to web server, looks at prices, and decides to purchase more. Provide users with current usage information. Users can change their bandwidth selections at any time.

7. Pilot Study Tested out UI and stability of the prototype with graduate students using a wired Ethernet network. Traces of download and upload bandwidth usages. Download Upload

8. Spring Semester Plan Deploy a 802.11a network using 10 access points around Soda Hall. Provide 50 graduate students with wireless cards for participating in the pricing experiments. Expected Results: Show users willing to interact with UI that only requires their attention when they need more bandwidth. Measure percentage of new and existing users requesting excess bandwidth when prices change.

9. Summary Determine effectiveness of using dynamic prices for allocating scarce bandwidth. Conduct a user study using a 802.11a WLAN. Expected Contributions: Collect traces of wireless bandwidth usages. Understand user acceptance to changing prices. Model users’ reactions to changing prices. Quantify effectiveness of congestion pricing for wireless bandwidth.