Cooperative Smartphones with Network Coding: From Theory to Practice

Transcription

1 Cooperatve Smartphones wth Network Codng: From Theory to Practce Anh Le Lorenzo Keller Blerm Cc Hülya Seferoğlu Athna Markopoulou Chrstna Fragoul Unversty of Calforna Irvne École Polytechnque Fédérale de Lausanne Supported by AFOSR MURI and ArmaSusse W+T

2 Applcatons of Network Codng? Recurrent questons about network codng: Is t mplemented n practce? How much beneft does t brng? How much s the overhead? Show me an eample applcaton! Last year we developed a network codng scheme for a wreless multhop network for uncast traffc. H.Seferoglu A.Markopoulou K.K. Ramakrshnan I2NC: Intra- and Inter- Sesson Network Codng for Uncast Flows n Wreless Networks n INFOCOM Ths year we mplemented network codng on smartphones 2

3 Why Smartphones? Ubqutous Androd n partcular: fastest growng among smartphones open source. Equpped wth multple network nterfaces and ncreasng computatonal/storage capabltes Stll lmted resources (bandwdth CPU energy) 3

4 Cooperatve Vdeo Streamng on Smartphones Scenaro The Internet Vdeo Source Youtube Netfl etc. Vdeo Proes Several users wthn promty of each other Interested n vewng the same vdeo at the same tme (stored locally or remotely) Some or all of them have a cellular connecton Base Statons Moble-to-moble connectons possble va bluetooth or wf. Smartphones 4

5 Cooperatve Vdeo Streamng on Smartphones Eamples The Internet Vdeo Source Each ndvdual user may not have hgh enough bandwdth to stream a hgh qualty vdeo (due to bad tme-varyng or no cellular connecton) Base Statons Specal case: sharng a vdeo stored on one of the phones Smartphones 5

6 Cooperatve Vdeo Streamng on Smartphones Queston The Internet Vdeo Source How to best utlze all resources to mamze the (common) vdeo rate seen by users? Base Statons Ths scenaro lends tself naturally to network codng. NC enables users to receve vdeo rate = ther mncut. Smartphones 6

7 Cooperatve Vdeo Streamng on Smartphones Key Ingredents The Internet Vdeo Source 1. Cooperatve use of cellular lnks Schedulng across 3G lnks 2. Cooperatve use of local lnks Hybrd Push+Pull Network Codng+Broadcast Base Statons 3. Implementaton on Androds. Smartphones 7

8 Related Work Network codng on moble devces NC Implementaton on laptops COPE: Katt et al. XORs n th ar: practcal wreless network codng SIGOCOMM 2006 Y. Park C. o S. Yun H. Km Mult-room IPTV delvery through pseudo-broadcast over IEEE lnks n Proc. of VTC Tape Tawan May S. Sen N. K. Madabhush S. Baneree Scalable wf meda delvery through adaptve broadcasts n Proc. of NSDI San ose CA Aprl NC Implementaton on phones and tablets Baochun L s Utoronto: Iphone Ipad Computaton/feasblty: Wang and L: [IWQoS 2006 Infocom 2007].. Gesture Flow [Infocom 2011]: streamng gestures n nteractve applcatons across pads F. Ftzek s Aalborg Unversty: Noka phones Computaton/Feasblty: M.Pederse F. Ftzek T.Larsen Implementaton and peeformance evaluaton of network codng for cooperatve moble devces n IEE CCWN Workshop May CN PctureVewer: a moble applcaton usng network codng EW 2009 workshop at Aalborg Error recovery n broadcast LTE lnks: P. Vngelmann M. V. Pedersen F. H. P. Ftzek and. Hede On-the-fly packet error recovery n a cooperatve cluster of moble devces Globecom

9 Related Work Cooperaton Cooperatve Moble Devces DTNs Moble Socal Networks. Network Codng-based P2P C. Gkantsds P. R. Rodrguez Network codng for large scale content dstrbuton n Proc. of Infocom Mam FL March M. Wang B. L R2: random push wth random network codng n lve peer-to-peer streamng n IEEE SAC vol. 25(9) pp Dec Z. Lu C. Wu B. L S. Zhao UUSee: large-scale operatonal on demand streamng wth random network codng n Proc. of Infocom San Dego CA March B. L D. Nu Random network codng n peer-to-peer networks: from theory to practce n Proceedngs of the IEEE vol. 99(3) pp March

10 Related Work NUM Formulaton Network Codng & NUM for wreless multhop networks D. S. Lun N. Ratnakar M. Medard R. Koetter D. R. Karger T. Ho E. Ahmed and F. Zhao Mnmum-cost multcast over coded packet networks n IEEE Trans. on Informaton Theory vol. 52(6) une L. Chen T. Ho S. Low M. Chang and. C. Doyle Optmzaton based rate control for multcast wth network codng n Proc. of Infocom Anchorage AK May Yuan Z. L W. Yu and B. L A cross-layer optmzaton framework for mult-hop multcast n wreless mesh networks n IEEE SAC vol. 24(11) Nov Z. L B. L and M. Wang Optmzaton models for streamng n multhop wreless networks n Proc. of ICCCN Honolulu HI Aug Network Codng & NUM for P2P networks M. Chen M. Ponec S. Sengupta. L P. A. Chou Utlty mamzaton n peer-to-peer systems n Proc. of ACM Sgmetrcs Annapols MD une S. Lu R. Z.-Shen W. ang. Reford M. Chang Performance bounds for peer-asssted lve streamng n Proc. of ACM Sgmetrcs Annapols MD une Z. Shao and S.-Y. R. L To code or not to code: rate optmalty of network codng versus routng n peer-topeer networks n IEEE Trans. on Communcatons vol. 59(4) pp Aprl C. Lang M. Zhao and Y. Lu Optmal bandwdth sharng n multswarm multparty p2p vdeo-conferencng systems n IEEE/ACM Trans. on Networkng March S. Hua Y. Guo Y. Lu H. Lu and S. S. Panwar Scalable vdeo multcast n hybrd 3g/ad-hoc networks n IEEE Trans. on Multmeda vol. 13(2) pp Aprl M. Ponec S. Sengupta M. Chen. L P. A. Chou Mult-rate peerto-peer vdeo conferencng: a dstrbuted approach usng scalable codng n Proc. of ICME New York NY uly D.-C. Tomoze and L. Massoule Flow Control for Cost-Effcent Peer-to-Peer Streamng n Proc. of Infocom San Dego CA March

11 Key ngredents - revsted The Internet Vdeo Source 1. Cooperaton: use cellular lnks and local lnks 2. Network codng: ntra-sesson applcaton-layer 3. Broadcast: use wreless+nc effcently overhearng on androds 4. Implementaton on Androds Smartphones 11

12 Outlne NUM formulaton and soluton H.Seferoglu L. Keller B.Cc A. Le A. Markopoulou Cooperatve Vdeo Streamng on Smartphones n Allerton 2011 Mcrocast: mplementaton+demo on androds L. Keller A. Le B.Cc H.Seferoglu A. Markopoulou C. Fragoul Mcrocast: under submsson Ongong Work 12

13 NUM Formulaton Cooperaton & Uncast The Source Downlnk 3g/4g C p Smartphones C p g mau ( ) s. t. N g g N C C (1 τ N { } Optmze vdeo rate: 0 N 0 N N p (1 γ ) N N p ) τ { } N N Interference Flow conservaton constrants Capacty constrants { } 13

14 Downlnk 3g/4g The Source C p Smartphones C p g NUM Formulaton Cooperaton & Broadcast mau ( ) s. t. N g g f N H C (1 0 N 0 N N f mn{ C τ Optmze vdeo rate: p γ ) N N N N } (1 p { } { } ) τ Interference Flow conservaton constrants Downlnk and local area capacty constrants N H 14

15 NUM Formulaton Cooperaton & Broadcast & NC Downlnk 3g/4g The Source C p Smartphones C p g mau ( ) s. t. N g g f N H C (1 0 N 0 N N f mn{ C τ Optmze vdeo rate: p γ ) N N N N (1 p )} τ { } { } Flow conservaton constrants Downlnk and local area capacty constrants N H Interference 15

16 NUM Soluton 16 ) ( ') ( 1 = U λ Rate Control at the Source N N p C s t N N ) (1.. ) ( ma η λ Downlnk Rate Control γ τ η τ τ N H N H s t p C.. )}) (1 mn{ ( ma Local Area Rate Control/Schedulng Queue Update at the Source Queue Update at Smartphones N t t t t N t + = + + )]} ( ) ( [ ) ( { 1) ( β λ λ N N t g t t t t + = + + )]} ( ) ( [ ) ( { 1) ( β η η Cooperaton & Broadcast & NC γ τ η τ τ N H N H s t p C.. )}) (1 } mn{ ( ma Cooperaton & Broadcast & No-NC γ τ τ η τ N N N N s t p C.. ) (1 ma Cooperaton & Uncast & NC/No-NC

17 Performance Evaluaton Numercal Results: throughput vs # of users C =1 p =0 C =1 p =0 C =1 p =0 C =1 p =0.2 17

18 From NUM to Implementaton Can use numercal smulaton to: understand the effect of varous parameters check real eperments Implementaton should mmc the optmal soluton How to determne source vdeo rate? Optmal downlnk rates? Optmal moble-to-moble rates Whch moble should transmt? What nformaton needs to be echanged? 18

19 Hardware platform Implementaton Hardware Google Neus S 1 GHz Corte A8 512 MB RAM Network connectons cellular (3G) b Bluetooth 2.1+EDR 19

20 Software platform Androd 2.3 Applcaton wrtten n ava runs on Androd (moble phones tablets) ava 2 SE (laptops etc.) Implementaton Software 20

21 Applcaton Archtecture GUI and Vdeo player Segment reorderng and cachng Abstracon layer for streamng protocol Requester: Download segments from source Local Collabora/on (and network codng) Network layer Downlnk: WF/3G Local lnk: Bluetooth/WF (w. or w/o overhearng) 21

22 NCUtls : l Feasblty of Network Codng on: not a (maor) challenge ava (and C) lbrares avalable at: Parameters: GF(2 8 ) generaton sze m=25 packet sze n=900 bytes (<MTU). Table look-up multplcatons XOR addtons RLNC encodng Progressve decodng Performance: Ma (.e. at 100% CPU) encodng/decodng rate w/o optmzatons: 3.5 Mbps pror state-of-the-art for phone 3G: 1.5 Mbps Pck fracton (25%) of coeffcents randomly: 4.5 Mbps (the rest set to 1) Natve C mplementaton: 20 Mbps (à can support > 50 phones n local network) Encodng becomes a problem when sendng to many peers Bottleneck: saturate CPU or network frst? Overhearng to the rescue 22

23 Handlng Multple Interfaces: a challenge Androd s optmzed for space and battery 3G WF Bluetooth Smultaneously usng multple nterfaces: 3G operates ndependently of Bluetooth or WF Bluetooth and WF: on the same chp not ndependent We used 3G and (WF or BT) 3G and WF: androds turns off one of the two We avoded usng Androd Wf Manager. We develop custom controller for Wf nterface We re-mplemented network layer (to provde routng and datagram communcaton) transparently of the underlyng lnk layer 23

24 Broadcast (Overhearng) a maor challenge Bluetooth: broadcast not supported WF: doable but dffcult A B WF Broadcast: not the best opton (base rate relablty) WF Overhearng on androds (vs. PCs) s challengng: Have to root the phone Drver for overhearng not avalable on all devces Snffer: we had to buld custom C/C++ lbrares to provde overhearng API Flter: dscard rrelevant overheard packets Overhearng works n nfrastructure but not n ad-hoc mode 24 C

25 Overhearng cont d Pseudo Ad-hoc mode Challenge: - Overhearng not possble n ad-hoc mode - Infrastructure mode: but redundant transmssons A AP B Soluton: Pseudo-adhoc - nfrastructure mode - A sends traffc to AP - B and other nodes overhear - AP does not forward traffc A AP B 25

26 NC + Overhearng: worth the effort measurement results 4 phones 2 download from 3G Total 3G rate: 1 Mbps (500 Kbps per phone) Recevng rate per phone: 1 Mbps WF LAN: 11Mbps Wth NC + Overhearng: LAN traffc measured: 2.24 Mbps Estmated number of phones to congest LAN > 12 Wthout NC + Overhearng: LAN traffc measured: 3.63 Mbps Estmated number of phones to congest LAN : >6 4 phones one dssemnates to others no 3G Smlar benefts 26

27 Applcaton Archtecture - revsted GUI and Vdeo player Segment reorderng and cachng Abstracon layer for streamng protocol Requester: Download segments from source Local Collabora/on (and network codng) Network layer Downlnk: WF/3G Local lnk: Bluetooth/WF (w. or w/o overhearng) 27

28 Coordnatng Multple 3Gs Scheduler One node s responsble to schedule the download of segments Each node s assgned a number of segments to download proportonally to ther 3G rates Scheduler handles download errors nodes leavng and 3G stalled Ongong work: ont 3G and local rate control and schedulng 28

29 Local Dstrbuton R2 NC+Push has poor performance due to hgh redundancy packets resulted from: Tmng of the breakng sgnal/feedback Small segment sze (lmted by moble CPU) Regular Pull (Bttorent-lke) does not take advantage of broadcast Our proposal: A Hybrd Push/Pull Intal push broadcast generaton Pull: report dmensons mssng For broadacst: broadcast the ma number of dmensons mssng by any recever. Subsequent pulls support mult-hop 29

30 Mcrocast n Acton Scenaro 1 2 HTTP Server Base staon downloadng over 3G lnk cooperaon over wf lnk overhearng over wf lnk 3 4

31 Mcrocast n Acton Demo Vdeo at: 31

32 Net Steps Characterze performance n practce Ma achevable rate per user: mn-cut Benefts depend on local network vs. 3G rate + CPU. Measurements show that Mcrocast acheves mn-cut for low 3G rates Brdge gap between NUM and mplementaton Rate control and schedulng on cellular and local lnks Beyond the one-hop scenaro Make Mcrocast publcly avalable: Androd applcaton PC/laptop applcaton ava lbrary 32

33 Thank you!