Delay-tolerant Networking using Wi-Fi Direct - Droidcon 2013

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Mobile connectivity is notoriously poor in football stadia due to their construction and the high density of users. Yet, football fans increasingly expect the same level of connectivity and access to services that they experience elsewhere. In this talk, we present our proposed solution – sharing Internet connectivity and content over data connections betweens fans’ smartphones that form a delay tolerant network (DTN).

The talk is focuses on: the issues existing technologies face when attempting to provide Internet connectivity in densely populated areas; the delay-tolerant network developed in the Digital Stadium research project; a discussion of some the Wi-Fi Direct issues faced when developing the DTN; a summary of the User-centred approach so that the application could gain traction amongst fans; and the results of the deployment during match days.

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Delay-tolerant Networking using Wi-Fi Direct - Droidcon 2013

  1. 1. Delay-tolerantNetworking UsingWi-FiDirect Stephen Naicken Visiting Research Fellow, Sussex University Droidcon 2013
  2. 2. Outline The Problem The Solution Wi-Fi Direct Deployment in the AMEX Community Stadium, Falmer Results Future work and Conclusions · Poor mobile data connectivity in stadia· · Pocket Switched Network implementing a distributed cache with idempotent HTTP POST · · Trials and tribultations· · · · 2/61
  3. 3. The Problem Poor in-stadia mobile data connectivity
  4. 4. Dr. Ian Wakeman, Senior Lecturer at Sussex University. UEFA Champions League Final, 2012.
  5. 5. Project EPSRC-funded research project to investigate the use of smartphones to build new ways of communicating within stadiums · 5/61
  6. 6. In-stadia Mobile Data Experiences Smartphones offer opportunities to improve the visitor experience But poor connectivity in-stadia is a barrier to deployment of these applications · Live scores and league tables Seat location service Pie and pint ordering Video highlights and goal-line replays · · · · · 6/61
  7. 7. The American Express Community Stadium Opened in 2011 Capacity of 30750 Home to Brighton and Hove Albion Football Club · · · Dominic Alves. http://www.flickr.com/photos/dominicspics/5606852371/
  8. 8. In-stadia Mobile Data Experiments 8/61
  9. 9. Problem Statement In a typical stadium, the concrete and steel construction and large crowds combine to make mobile Internet access very unreliable How can we improve connectivity so that fans can access matchday services? What are the possible solutions? · · · Do nothing, but EPSRC would not be impressed Invest in mobile network infrastructure to increase capacity Wi-Fi · · · 9/61
  10. 10. Issues with Mobile Networks Investment in mobile networks will not yield benefits to all fans unless all major operators invest Mobile network operators unlikely to be supportive of cash-stripped clubs A UK operator has invested approx. £1m to improve mobile data connectivity at leading Premier League club's stadium · · · Fans still complain of poor connectivity and the club accept that video can still not be delivered to all fans - 10/61
  11. 11. Issues with Wi-Fi Cost Performance Issues · Typically quoted cost to British clubs is around £500000 US market costs could be around $6m Technology spend at British clubs is typically low Many Football League clubs would struggle to justify costs (low ROI) · · · · · It doesn't work too well Low numbers of simulataneous users User experience is typically poor - e.g. Gillette Stadium · · · 11/61
  12. 12. The Solution Pocket Switched Networking
  13. 13. Technology Idea 13/61
  14. 14. Technology Idea 14/61
  15. 15. Technology Idea 15/61
  16. 16. Technology Idea 16/61
  17. 17. Supporting HTTP GET
  18. 18. Supporting HTTP GET
  19. 19. Supporting HTTP GET
  20. 20. Supporting HTTP GET
  21. 21. Supporting HTTP GET
  22. 22. Supporting HTTP GET
  23. 23. Supporting HTTP POST
  24. 24. Supporting HTTP POST
  25. 25. Supporting HTTP POST
  26. 26. Supporting HTTP POST
  27. 27. Supporting HTTP POST
  28. 28. Wi-Fi Direct Trials and Tribulations
  29. 29. Connectivity Bluetooth Tethering Ad-hoc Wi-Fi Wi-Fi Direct · System dialog prompts· · Unrestricted Internet access for all· · Not part of the API and requires superuser· · Only option open to us· 29/61
  30. 30. Starting Wi-Fi Direct on ICS WifiP2pManager p2pManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE); // Wfd callbacks on a handler thread channel = p2pManager.initialize(context, wfdHandler.getLooper(), channelListener); if (!wifiManager.isWifiEnabled()) { // remember to handle exceptions gracefully Class p2pManagerClazz = Class.forName ("android.net.wifi.p2p.WifiP2pManager"); Method method = p2pManagerClazz.getMethod("enableP2p", new Class[]{WifiP2pManager.Channel.class}); method.setAccessible(true); method.invoke(p2pManager, channel); method.setAccessible(false); } JAVA 30/61
  31. 31. Wi-Fi Protected Setup WifiP2pConfig config = new WifiP2pConfig(); config.deviceAddress = device.deviceAddress; JAVA // Push-Button Configuration config.wps.setup = WpsInfo.PBC; JAVA // Display pin on client, enter on GO config.wps.setup = WpsInfo.DISPLAY; JAVA // Display pin on GO, enter on client config.wps.setup = WpsInfo.KEYPAD; JAVA p2pManager.connect(channel, config, wfdActionListener) JAVA 31/61
  32. 32. WPS without the dialog prompts - API 16-17 Automatic acceptance of WPS PBC dialogs is possible Once again using reflection API 16-17: WifiDirectAutoAccept.java (AllJoyn) Interception of PBC dialogs only occurs when app is in foreground · · · · 32/61
  33. 33. And API 18... Method m = wifiP2pManager.getClass().getMethod("startWps", channel.getClass(), WpsInfo.class, WifiP2pManager.ActionListener.class); WpsInfo wpsInfo = new WpsInfo(); wpsInfo.setup = WpsInfo.PBC; m.invoke(wifiP2pManager, channel, wpsInfo, wfdActionListener); JAVA Starts a two minute WPS window at the Group Owner (GO) Execute WPS PBC on client to connect to GO PBC supports only one connection attempt at a time At supplicant, CTRL-EVENT-WPS-OVERLAP · · · · 33/61
  34. 34. Wi-Fi Legacy Connections to GO BroadcastReceiver receiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { if(intent.getAction().equals (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION)){ wifiP2pManager.requestGroupInfo(channel, new WifiP2pManager.GroupInfoListener() { @Override public void onGroupInfoAvailable(WifiP2pGroup group) { if(group != null){ // clients require these String ssid = group.getNetworkName(), String passphrase = group.getPassphrase() } } }); } } }; registerReceiver(receiver, new IntentFilter (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION)); wifiP2pManager.createGroup(channel, wfdActionListener); JAVA 34/61
  35. 35. Other Issues Samsung devices will destroy the Wi-Fi Direct group when the last remaining client disconnects Samsung devices have supported simultaneous infrastructure Wi-FI and Wi-Fi Direct connections since API 16 Samsung S4 persistent group passphrase will change when group is destroyed and re-created On some devices, it is possible to crash the Wi-Fi driver with many Wi- Fi Direct operations · · · · 35/61
  36. 36. Deployment App Deployment, Fan Interaction & Feedback
  37. 37. User-centred Design Methodology Built Fan Pilot group of Android users Worked closely with key BHAFC staff to identify business-driven services · Focus groups In-app user experience sampling Observation and accompanied journeys · · · · 37/61
  38. 38. Survey 1628 season ticket holders responded 95% smartphone users Profile data e.g. Data usage, services used in stadium Only 6% reported no connectivity issues Sought participation consent in the survey · · · · · 38/61
  39. 39. Services: Matchday Statistics 47/61
  40. 40. Services: Twitter 48/61
  41. 41. Services: Traffic 49/61
  42. 42. Battery and Data Limits 50/61
  43. 43. Results Installs, Round Trip Times, Data Transfered and More
  44. 44. Deployments Brighton vs. Wolves - 4th May 2013 Brighton vs. Bolton - 21st September 2013 · Final game of the season Brighton guaranteed place in Playoffs, but will their arch-rivals, Crystal Palace join them Although on a small scale, first successful deployment · · · · Largest deployment to date, 127 users Comprehensive testing across a wide range of devices Optimisation to applications' Wi-Fi Direct state machine · · · 52/61
  45. 45. Application Views (04/05/13) 53/61
  46. 46. Round Trip Times on the DTN Content is cached and replicated across the mobile phones The time from sending HTTP GET request to receiving a response Where the content is not available in the phone's cache and the phone does not have a data connection And the response is from either some other phone's cache or data connection Median RTT = 131s · · · · · 54/61
  47. 47. The app was a godsend on the final day of the season. It’s hit-and-miss as to whether you can get a signal at the Amex, but the app meant I knew the ever-changing scores and league positions throughout the afternoon. “ ”
  48. 48. Connectivity Graph (21/09/13) 56/61
  49. 49. Results (21/09/13) 338 installs and 127 in-stadium users 595 DTN Connections 1GB over DTN 60% of data over DTN 4006 requests from UI Median delay 108s · · · ·· · · 57/61
  50. 50. Future Work And some conclusions
  51. 51. Conclusions Successful deployments of a pocket-switched network using Wi-Fi Direct Positive user feedback from both club and fans Fans have improved access to matchday services · · · 59/61
  52. 52. (Immediate) Future Work Optimise battery management by optimising the protocols and code Integrating the app with BHAFC's ticketing system Distributing video replay in-stadia Deploying stadium-wide through the Play store Likely University Spin-off · · · Self-destructs when you leave the stadium to comply with digital rights · · Aiming for in-stadium user numbers in the order of thousands Target date: Brighton vs. Blackburn - 9th November · · · 60/61
  53. 53. Questions? stephenn@sussex.ac.uk twitter stephennaicken www www.digitalstadium.mobi

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