EmNet: Satisfying The Individual User Through Empathic Home Networks J. Scott Miller, John R. Lange & Peter A. Dinda Department of Electrical Engineering and Computer Science Northwestern University Prescience Lab

Summary User satisfaction in home broadband environments varies dramatically across users –There is no canonical user –Demonstrated with user study EmNet: use per-user feedback to schedule external link –User satisfaction increases by 20% First network scheduling policy to use per-user satisfaction

Outline User satisfaction in home networks –User study with controlled conditions EmNet: Design and implementation –Targets home network routers Evaluation –User study with controlled conditions

Per-User Variation Traditional optimizations focus on a canonical user –Abstract definition for the average user Real users have large variability –Different performance demands to achieve satisfaction Optimizing for a single user is non-optimal –Leads to both over and under provisioning

User study Variance in typical home network users –Measured satisfaction with network performance –Emulated home network environment 20 study participants –Taken from University population 3 web applications –Wikipedia, Image labeler, streaming video 16 cross traffic scenarios –Both upload and download Collected per scenario satisfaction ratings –Satisfaction measured on 10 point scale

Study Testbed Internet Cross Traffic Client Cross Traffic Server Network Bridge (Home Router) Test Subject Web Proxy Emulated Broadband Link

Interface Measurements collected via web interface –Overlaid onto web pages viewed by users Router injected code in every web page viewed

Study Results (Streaming Video) Large Per-User variation in satisfaction Average satisfaction varies between cross traffic scenarios

Implications There is no canonical user –Users have different performance expectations Per-user satisfaction can be collected in real-time Optimal network scheduling requires knowledge of user satisfaction

EmNet Designed to be embedded in home network routers –Optimizes home networks based on user satisfaction Components –User Interface (Satisfaction sensor) –Proxy server and Interface injector –Policy Controller –Network Controller

Proxy Server and User Interface Injects JavaScript interface onto web pages Monitors and tracks network traffic –Associates connections with user input signals –FlowSets Real time measurements of user satisfaction –Corresponding to a given group of connections –Drives bandwidth allocation decisions On screen slider Real time satisfaction measurements Used as input to policy controller

Policy Controller Optimizes bandwidth allocation between network flows –Maximizes user satisfaction –Minimizes over-provisioning Output –percentage of bandwidth allocated per FlowSet Input –User satisfaction measurements –Connections associated with each measurement Prevents link monopolization –Guaranteed minimum static allocation –Allocates bandwidth between FlowSets and background traffic –Cost function User 1 Back Ground User 2 Back Ground Static BWDynamic BW User 1 User 2 Back Ground UserBack Ground Satisfaction Rating Value

Network Controller Manages network connection performance –Assigns actual bandwidth FlowSets Weighted Fair Queuing approach –Weights are set to ensure proportional allocation under load

System Architecture User drives queuing decisions Designed for home network routers

Evaluation EmNet prototype implementation – Installed in network testbed Network controller in network bridge – FreeBSD and DummyNET Simplistic cost function –Users effectively pay for data (~$10)

User Study Separate from initial variability study –18 participants from university population Same 3 applications –Wikipedia, Image Labeler, Streaming Video Subset of initial cross traffic scenarios –Most significantly affecting satisfaction User interface was injected onto every page –Collected results with and without control active

Evaluation Testbed Internet Cross Traffic Client Cross Traffic Server Network Bridge (Home Router) Test Subject Web Proxy Satisfaction Measurements Network Controller

Results Image LabelerVideo Streaming

General Results EmNet increases user satisfaction with a nominal increase in bandwidth usage –20% more satisfied than without network control –12% more satisfied than static WFQ –6% more bandwidth than static WFQ Experimental cost function ineffective –Users rarely decreased the slider to lower incurred cost –Cost function had no real world value

Additional information in Northwestern Technical Report Prescience Lab – Empathic Systems – John Lange –