Open Internet Challenges in Mobile Broadband Networks

1
Open Internet Challenges in Mobile Broadband
Networks

• Jennifer Rexford
• Princeton University
• http//www.cs.princeton.edu/jrex

2
FCC and Open Internet

• Open Internet Order (2010)
• Transparency
• No blocking
• No unreasonable discrimination
• Open Internet Advisory Committee (2012)
• Track effects of the Open Internet Order
• Provide recommendations to the FCC
• Representatives from community organizations,
  equipment manufacturers, application providers,
  venture capital firms, ISPs, Internet governance,
  and academia

3
Mobile Broadband Working Group

• Mobile broadband
• Increasingly crucial part of Internet access
• Yet, still at an early stage of development
• Special treatment in Open Internet Order
• Network practice transparency
• Certain no blocking requirements
• Wider latitude for differentiated service
• Three case studies
• ATT limiting the FaceTime application
• Mobile apps overloading signaling resources
• Carriers limiting use of Google Wallet

4
Apple FaceTime

• High-quality video chat service
• Originally available only over WiFi

5
ATT and FaceTime A Timeline

• Jun12 Apple announces FaceTime over cellular
• Carrier restrictions may apply
• Aug12 ATT limits use of FaceTime over
  cellular
• Limited to customers with the Mobile Share plan
• Sprint and Verizon announcesupport on all data
  plans

6
ATT and FaceTime Timeline

• Aug12 Some advocates and press denounce
• ATT is violating FCCs Open Internet Order
• FaceTime competes with ATTs voice/video
  telephony
• Reasonable network management practices do not
  include favoring one data plan over another
• Aug12 ATT responds in a blog posting
• ATTs policy regarding FaceTime is fully
  transparent
• ATT does not have a competitive video chat app
• FCC rules dont regulate availability of
  preloaded apps

7
ATT and FaceTime A Timeline

• Sep12 Public interest groups respond
• Announcing intent to file a formal FCC complaint
• Oct12 ATT customer files an FCC complaint
• Blocking of FaceTime on his unlimited data plan
• Nov12 ATT relaxes limitations on FaceTime
• Supporting FaceTime on tiered plans over LTE
• though other customers would not have access

8
ATT/FaceTime Issues

• Pre-loaded application
• Available to all users of popular phone
• Accessed via devices core calling features
• High bandwidth requirements
• Symmetric bandwidth usage, with asymmetric
  capacity
• Limited adaptation in the face of congestion
• Staged deployment
• Rapid adoption could lead to unpredictable load
• Initially limit the number of users accessing an
  app
• Enforcement point
• Usage limited on the device, not in the network

9
Apps With High Signaling Traffic

• Signaling channel
• Keeps track of mobile devices and their locations
• Notifies network when a device wants to send
  traffic
• Overloaded signaling channel
• Prevents new requests from reaching the network
• Can become congested before the network bandwidth
• Unique issue in cellular networks
• Due to Radio Resource Control function
• and the shared, constrained resources

10
Chatty Applications

• Periodic transfers
• Keep-alive messages (e.g., push services, NATs)
• Polling (i.e., has something happened?)
• Ad updates
• Measuring user behavior
• Skewed usage of signaling resources
• Up to 30 resource usage for lt2 traffic volume
• In some cases, 90 signaling usage by one
  application
• Also drains the battery on the phone
• Machine-to-machine traffic could make this worse

http//web.eecs.umich.edu/zmao/Papers/periodic_ww
w2012.pdf
11
Managing Signaling Load is Hard

• End device
• Strong incentives, and (some) app-level knowledge
• But, incomplete control over application behavior
• Application developer
• Complete knowledge of own application, but not
  others
• But, limited knowledge of the network state
• Network
• Sees all traffic and controls resource scheduling
• But, incomplete knowledge of applications, or
  ability to infer app before harm has been caused

12
Signaling Management Challenges

• Application-specific management
• Adjusting timers for periodic polling
• Piggybacking of requests on data traffic
• Application-level signaling control
• Huge number of applications
• Average lifetime of 30 days and revenue of 700
• E.g., ATT has worked with 100 app developers
• Complex optimizations
• Cross-application and cross-device
• Joint management of bandwidth and signaling load

13
Going Forward

• Network management is challenging
• Large mix of rapidly evolving applications
• Growing number of mobile devices
• Limited bandwidth and signaling capacity
• The technical details matter
• Capabilities of todays equipment
• Best practices for network management
• Tension between competing goals
• Managing limited cellular network resources
• Encouraging innovation in applications