1 / 71

Resource sharing in mobile wireless networks

Explore resource sharing in mobile networks for enhanced connectivity. Topics cover data dissemination, bandwidth sharing, and peer-to-peer communication. Learn about 7DS application and limitations of current network models.

ddunford
Download Presentation

Resource sharing in mobile wireless networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Resource sharing in mobile wireless networks Maria Papadopouli Computer Science Department Columbia University http://www.cs.columbia.edu/~maria

  2. Academic background • Columbia University Ph.D. candidate Fall 1996- advisor Prof. GolubchikFall 1996–1998 advisor Prof. SchulzrinneFall 1998- • New York University M.S. Computer Science May 1994 • University of Crete B.S. Computer Science June 1992

  3. References on resource sharing in mobile ad hoc networks with Prof. Schulzrinne • “Effects of power conservation, wireless coverage & cooperation on data dissemination among wireless devices “, ACM MobiHoc 2001 • “Performance analysis of 7DS a data dissemination & prefetching tool for mobile users”,IEEE Sarnoff 2001, best paper/poster award • “7DS in mobile ad hoc networks”,Globecom 2000 • “Performance of data dissemination among mobile devices”,journal submission, 2002 • “Design & implementation of a P2P data dissemination & prefetching tool for mobile users”,Metro 2001 • “Network connection sharing in ad hoc wireless network among collaborative hosts”,Nossdav 1999

  4. References on video on demand with Prof. Golubchik • "A Scalable Video on Demand server for a Dynamic Heterogeneous Environment", Lecture Notes in Computer Science, Springer 1998 • "Support  of VBR Video Streams Under Disk Bandwidth Limitations", ACM SIGMETRICS Performance Evaluation Review 1997 •  (with also J.C-S. Lui), "A survey of approaches to fault tolerant design of video on demand servers: Techniques, analysis and comparison", Special issue of Parallel Computing Journalon Parallel Data Servers and Applications1998

  5. Outline • Introduction • Background on wireless data access • Motivation • Overview of 7DS • Performance analysis on 7DS • Conclusions • Future work

  6. Background • Fast growth in pervasive computing devices • Fast wireless data servicesgrowth • Base stations for wireless WAN will not keep pace • Regulatory, environmental & cost barriers for a dense deployment Users experience intermittent connectivity & limited data access

  7. Mobile information access Dependency oninfrastructure : • Wireless WAN eg 802.11, 3G, CDPD, GSM, Bluetooth, Ricochet • Infostations (Rutgers) • When a client is in the proximity of the server, it access the data • Peer-to-Peer • Routing in mobile, ad hoc & sensor networks

  8. Mobile information access Interactivity model : • Synchronous • Users directly access or request the data • Asynchronous (using prefetching) • Hoarding (Coda [CMU], Seer [UCLA])

  9. Limitations of infostations & wireless WAN • No communication infrastructure eg field operation missions, tunnels, subway • Emergency • Overloaded • Expensive • Wireless WAN access with low bit rates & high delays

  10. Host A Host B Limitations of ad hoc networks • All hosts cooperative • Complete path for the communication of two hosts

  11. Limitations of hoarding • Only files • Files exist prior to disconnection • No dynamic generated information

  12. Wireless data services • Delay tolerant • Location-dependent services • User location hints at data needs • Overhead to discover, access & update local data

  13. Challenge Accelerate data availability & enhance dissemination & discovery of information under bandwidth changes & intermittent connectivity to the Internet due to host mobility considering power, bandwidth & memory constraints of hosts

  14. Our Approach Increase data availability by enabling devices to share resources • Information sharing • Message relaying • Bandwidth sharing • Self-organizing • No infrastructure • Exploit host mobility

  15. Outline • Introduction • Background on wireless data access • Motivation • Overview of 7DS • Simulations & Analysis on 7DS • Information dissemination • Message relaying • Bandwidth sharing • Conclusions • Future work

  16. 7DS • Application • Zero infrastructure • Relay, search, share & disseminate information • Generalization of infostation • SporadicallyInternet connected • Coexistswith other data access methods • Communicates with peers via a wireless LAN • Power/energy constrained mobile nodes

  17. traffic, weather, maps, routes, gas station Examples of services using 7DS news WAN events in campus, pictures where is the closest Internet café ? pictures, measurements service location queries schedule info autonomous cache

  18. WLAN query WAN Host D data query Host A Information sharing with 7DS cache miss Host C WLAN cache hit data Host B Host A

  19. Power conservation • server to client • only servershares data • no cooperation among clients • fixed info server (infostation model) • mobile info server communication enabled on off time Forwarding FW query query • peer to peer • data sharing among peers Host C Host A Host B time 7DS options Cooperation Server to client Peer to peer Querying active (periodic) passive

  20. Outline • Introduction • Simulations & Analysis on 7DS • Information dissemination • Message relaying • Bandwidth sharing • wireless LAN • video on demand environment • Conclusions • Future work

  21. Simulation environment pause time 50 s mobile user speed 0 .. 1.5 m/s host density 5 .. 25 hosts/km2 wireless coverage 230 m (H), 115 m (M), 57.5 m (L) ns-2 with CMU mobility, wireless extension & randway model querier wireless coverage dataholder randway model

  22. Simulation environment pause time 50 s mobile user speed 0 .. 1.5 m/s host density 5 .. 25 hosts/km2 wireless coverage 230 m (H), 115 m (M), 57.5 m (L) ns-2 with CMU mobility, wireless extension querier wireless coverage 1m/s pause mobile host data holder

  23. data v2 v3 Simulation environment pause time 50 s mobile user speed 0 .. 1.5 m/s host density 5 .. 25 hosts/km2 wireless coverage 230 m (H), 115 m (M), 57.5 m (L) ns-2 with CMU mobility, wireless extension wireless coverage v1

  24. Dataholders (%) after 25 min high transmission power P2P Mobile Info Server Fixed Info Server 2

  25. 2 km 1 km 1 km Scaling properties of data dissemination wireless coverage R R 2 km If cooperative host density & transmission power are fixed, data dissemination remains the same

  26. Scaling properties of data dissemination (cont’d) wireless coverage R R/2 For fixed wireless coverage, the larger the densityofcooperative hosts, the more efficient the data dissemination

  27. Average delay (s) vs. dataholders (%) Fixed Info Server one server in 2x2 high transmission power 4 servers in 2x2 medium transmission power

  28. Average Delay (s) vs Dataholders (%)Peer-to-Peer schemes high transmission power medium transmission power

  29. r/2 v x x R/2 Scaling properties of data dissemination (cont’d) L wireless coverage of info server r v L x x R

  30. trapping model with particles C and T (traps) particles C perform random walk in 2D space particles T static, randomly distributed in space of infinite capacity particles T absorb C when C step onto them survival probability fn at long times n log (fn)  -An T C Modeling Fixed Info Server as diffusion-controlled process querier  particle C fixed info server trap trappingreceiving data

  31. Fixed Info Serversimulation and analytical results high transmission power Probability a host will acquire data by time t follows 1-e-at

  32. Outline • Introduction • Background on wireless data access • Motivation • Overview of 7DS • Performance analysis on 7DS • Information dissemination • Message relaying • Network connection sharing • Conclusions • Future work

  33. WLAN messages Host A Message relaying with 7DS WAN Gateway WLAN Message relaying Host B Host A

  34. Message relaying • Take advantage of host mobility to increase throughput • Hosts buffer messages & forward them to a gateway • Hosts forward their own messages to cooperative relay hosts • Restrict number of times hosts forwards

  35. Messages (%) relayed after 25 min(average number of buffered messages : 5) 2

  36. Outline • Introduction • Background • Motivation • Overview of the system • Performance analysis • Information dissemination • Message relaying • Network connection sharing • Conclusions • Future work

  37. Network connection sharing Host F WAN Host E Host A thin WAN links Hosts A & B dual-homed They act as gateways to WAN for hosts C & D Host D Wireless LAN Host C Host B

  38. Network connection sharingprotocol Host E WAN • Csends request for gateway • B & Arespond advertising their bandwidth in WAN link • 4.C selects least loaded gateway (eg A) • 5.A  Cadmission control thin wireless WAN links HostA HostD WLAN Host B Host C

  39. Benefits using network connection sharing • Statistical multiplexing for bursty traffic • Increase bandwidth utilization of the WAN links • 80% bandwidth utilization for Pareto traffic • Load balancing across gateways • For shared data applications : • Reduction of replicated data • Increase quality of service

  40. Outline • Introduction • Background on wireless data access • Motivation • Overview of the system • Performance analysis • Information dissemination • Message relaying • Network connection sharing • Conclusions • Future work

  41. Conclusions • Dominant parameters: • density of cooperative hosts • wireless coverage density of cooperative hosts & their mobility • For fixed cooperative hosts density & transmission power : scale area performance same • For fixed wireless coverage density : Density of cooperative host  performance 

  42. Conclusions (cont’d) • Probability a host will acquire data by time t in • Fixed Info Server : 1-e-at • Peer-to-Peer : 1-e-at • Message relaying is beneficial : • Probability a message will reach the Internet  • Utilization of available throughput  by taking advantage of host mobility

  43. Future work • Location-dependent applications & services • Actual traces & models for user mobility, access patterns & data locality • Enhanced power conservation mechanism • Security & micro-payment issues • Extension of network connection protocol • Generalization of diffusion models for P2P • Adaptive scalable algorithms for information discovery

  44. Summary of contributions in video on demand Novel multimedia retrieval scheduling algorithms In multi-disk environments : • adapt to bandwidth changes • maximize data retrieval forall streams using replication and multi-resolution In single-disk environments : • allocatedisk bandwidth in a fair manner

  45. Thank you!

  46. Future work: short term • More on power conservation for data dissemination • Peer-to-peer scheme using diffusion controlled processes • Prototype • Deployment of 7DS in CU campus & in Bremen • Public release of the code • Collaborations • IBM, HP, Bertelsmann & Limewire (Gnutella)

  47. Future work : longer term • Information discovery & dissemination in pervasive computing • Model & abstractions for the quality of information • Tight energy, bandwidth • Privacy & security for mobile, peer-to-peer applications • Scaling & structural properties

  48. multicast query wait to hear if Q is challenged multicast challenge run non-trivial computational task sends response Preventing DoS attacks Host Q Host R receives query verifies Q’s answer decides to cooperate

  49. send credentials send e-check wait for data from R send data Electronic check payment Host Q Host R verify R is known to the bank & authorized for 7ds receive e-check verify it is genuine store e-check

  50. send public key with report form query send query wait for data from R send data decrease counter send ack decrease counter send nack Token-based payment Host Q Host R check token counter verify R’s public key receive query increase token counter increase token counter senddata

More Related