Presentasjon om: "Gruppepresentasjon Virtual Transparent Directory with Mobile Ad-Hoc Networking Henning Berg Jon Oldevik Lars Kristian Snellingen Bye Mansur Ali Abbasi."— Utskrift av presentasjonen:
Gruppepresentasjon Virtual Transparent Directory with Mobile Ad-Hoc Networking Henning Berg Jon Oldevik Lars Kristian Snellingen Bye Mansur Ali Abbasi Sven Jørgen Karlsen
Virtual Transparent Directory with Mobile Ad-Hoc Networking Objectives –Learning to ”ad-hoc” –Implementing a simple solution to ad-hoc file sharing Approach –Reading theory; books and articles –Defining a prototype File Sharing on a virtual ad-hoc network –Analysing usage areas –Implementing the prototype Expected results –Knowledge on mobile ad-hoc networking and bluetooth… Technology: J2ME, Bluetooth Usage –An implemented prototype –Documentation of results
Mobile Ad-Hoc Networking About ad-hoc –Latin phrase: for this purpose –Also: refer to an improvised and often impromptu event or solution In computer networking –Ad-hoc is mostly associated with wireless devices. –Requires no base station. –Devices discover others within range to form a network –Connections are possible over multiple nodes –Devices out of range can be found by forwarding –Routing protocols provide stable connections even if nodes are moving around. Example: Sony's PlayStation Portable uses Ad-Hoc connection for wireless multiplayer gaming. MANET
More about MANETs Self-configuring network of mobile terminals connected by wireless links –Which form an arbitrary topology. The terminals are free to move randomly and organise themselves arbitrarily; May operate standalone or be connected to a larger (Inter)net. Minimal configuration and quick deployment –Natural or human-induced disasters, military conflicts, emergency medical situations etc. Earliest MANETs were called packet radio networks –Sponsored by DARPA in the early 1970s.. a short range alternative for ad-hoc HiMoNN (Highly Mobile Network Node) Example of ad-hoc application for tactical and rescue services etc.
Prototypeapplikasjon – Transparent Virtual Directory (TVD) Fildelingstjeneste der alle nodene i et ”tilfeldig” nett skal kunne dele filer med hverandre ved bruk av Bluetooth-kompatible enheter Skal brukes som grunnlag for resonnering om ad- hoc nettverk Flere problemområder knyttet til ”spontane” nettverk. Blant annet: –Master/slave-problematikk (server/klient) –Ruting –Filreplikering og eierskap av filer –Lastbalansering –Filforwarding
Virkemåte til TVD Tre scenarioer som kan beskrive de fleste situasjoner (ved å kombinere disse): 1.To noder i et nett hvor ‘node A’ ønsker å laste ned to filer som befinner seg fysisk på ’node B’ Tre noder i et nett hvor ‘node A’ ønsker å laste ned en fil fra ‘node B’ og en fil fra ‘node C’ Tre noder i et nett hvor ’node A’ og ’node B’ er innenfor rekkevidde av hverandre, og ’node B’ og ’node C’ er innenfor rekkevidde av hverandre. ’Node A’ ønsker å laste ned en fil fra ’node C’.
Scenario 1: To noder, ’node A’ ønsker å laste ned to filer fra ’node B’
Scenario 2: Tre noder, ’node A’ ønsker å laste ned en fil fra hver av de to andre nodene i nettet
Scenario 3: Tre noder, ’node A’ ønsker å laste ned en fil fra en node som ikke er direkte tilgjengelig for ’node A’
Problemområder: - Master/slave-problematikk, ruting, lastbalansering og filforwarding: - JSR82 som spesifiserer bruken av Bluetooth i J2ME-applikasjoner indikerer en master/slave-kategorisering av enheter - Mange noder i et nett kan føre til at mye av båndbredden blir brukt til kontrollpakker - Mobiler og PDAer har begrenset med prosessorkapasitet og minne, og store, tunge rutingsprotokoller kan bli et problem Vi tror en reaktiv point-to-point (hop-by-hop) rutingprotokoll vil være best for TVD. En gitt rute blir funnet når den trengs Vil trolig benytte JBAN – et rammeverk som fjerner master/slave- problematikken, lastbalansering og har innebygd ruting
Problemområder: Filreplikering og eierskap av filer - Vil begrense oss til at kun én node i et nett kan dele ut en fil med et gitt filnavn. Andre noder som laster ned denne filen vil ikke uten videre dele denne ut
Usage areas of Ad Hoc networking Social services –Dating, chatting Work related / ”useful” areas –Emergency areas –Military operations –Sensor Networks Entertainment –Gameplay Information sharing –File sharing –Streaming media services –Commercial and sales
Usage areas of TVD Sharing of image and music files Comercials / product information Work situasions –Document sharing –Collecting data from nodes
Example usage scenario of TVD Document sharing between coworkers at a meeting: –No papers –No possibility to forget / loose links –Don’t need to bring a big laptop, the cell phone is enough.
Other Related Ad-Hoc Bluetooth Applications Mobiluck (http://www.mobiluck.com/) –Sending messages and photos other to bluetooth users ProximityMail (http://www.inventop.com/index.htm) –Group-based message sending / subscription MeetingPoint (http://www.net-cell.com/MP/index.html) –Channel-based contact application (messaging) Freejack and sMan –”Bluejacking” software
Bluetooth - background Bluetooth is a wireless standard for interconnecting devices, using short -range, low-power, inexpensive radios. –Radio: 2.4 Ghz ISM band, license-free. 79 (23) channels of 1 Mhz. Gross rate <= 1 Mbits –Original idea: To get rid of the cables between devices (similar to infrared networks) Soon expands in scope and overlaps with WLAN and IR networks. –13 profiles (applications) built on stacks of more than 9 protocols. History: –1994: Ericsson initiated a SIG (special interest group) together with IBM, Intel, Nokia and Toshiba, to std. connecting mobile phones with other devices without cables. Named after Harald Blåtann II (940-981), a danish Viking king who unified Denmark and Norway (a brief period, between Harald Hårfagre and Olav the Saint). –1999: V1.0 released in 1500 pages (!). Triggers a parallell effort in IEEE 802.15, which looks at WPANs, but only std. the physical and data link layers. Purpose: Open std. managed by a neutral body. –2002: 802.15.1 approved by IEEE. –2004: V2.0 Core spec. with EDR (up to 3 Mbits speed) released. –Present/Future: The two stds. will converge?
Bluetooth - architecture Piconet: basic building block of a Bluetooth system –One master node, and up to7 active slave nodes (up to 255 parked nodes), <= 10 meters apart. –All communication goes through the master, direct slave-slave is not possible. The slaves are fairly dumb, basically just doing doing whatever their master tells them to do. –Technical note: a piconet is a centralized TDM system, with the master controlling the clock and allocating time slots. Scatternet: interconnected piconets, via bridge nodes.
Bluetooth – protocol stack Service Discovery Protocol (SDP): Inquire about services, find out how to access ● Object exchange (OBEX) Support “object exhanges”, basis for Synchronization Profile and File Transfer Profile. ● Radio Frequency Communication (RFComm): Emulates the std. serial port (RS-232) on PCs for integration with legacy devices. ● Logical link control adaptation protocol (L2CAP) Packet intf. to higher layers (m/s roles hidden at this layer), packet segmentation and reassembly. Multiplexes several logical channels over one physical link.
J2ME – Java Platform, Micro Edition What is it? –A set of technologies and specifications for small devices –Small-footprint subsets of Java SE components –Smaller virtual machine and leaner APIs targeted at consumer and embedded devices Why suitable for us? –Java Bluetooth API –Open, non-proprietary standard for bluetooth application development –Hides complexity of Bluetooth and allows focus on application development
J2ME – Java Platform, Micro Edition Not so MICRO after all…?
JBAN – A potential pain reliever? Pain: –The process of forming a scatternet out of piconets is usually not dynamic and practical –The scatternets formed are not robust –Routing and network management causes a lot of headache for the developer Pain relief: –JBAN: a open source Java library for Bluetooth networking –Provides a new way to form an ad-hoc network at the Java application level –Allows unlimited devices to form a network dynamically –More robust networks, no distinction between master and slave nodes –Routing and network management is performed at high level Possible pitfalls: –JBAN is relatively new (more or less a bundle of code in jar-file) –“Released” February 2006, no documentation, no reported experiences –May require some “hacking” to make it work the way we want it to To use or not to use? –No pain no gain…JBAN may help increase the gain and reduce the pain –Decision: Let’s try it out!
Project status So far so good: –Focused on background reading and understanding the technology and tools –Evaluated and abandoned several ideas before TVD: Triangular positioning of Bluetooth nodes Solutions for crisis management / emergency warnings –Now have a well elaborated, feasible idea: TVD –No external collaboration = free, independent development The path forward: –Ready to embark on coding / implementation Work in smaller subgroups, iterative Testing in a Bluetooth network simulator? –Will result in greater theoretical and practical insight into Mobile Ad-Hoc Networking and especially Bluetooth+J2ME –If successful in implementation and testing, further development may be interesting (perhaps as a open source project)
Future of Bluetooth Advancements in progress –Larger range –Higher transfer speeds –QoS improvements –Will become more feasible for more sophisticated use