4003-543/4005-742 Ad Hoc Networks
Module 1. Fundamentals -- Lecture Notes
Prof. Alan Kaminsky
Rochester Institute of Technology -- Department of Computer Science
"Ad Hoc"
- From the Merriam-Webster Online Dictionary:
-
Main Entry: 1ad hoc
Pronunciation: 'ad-'häk, -'hOk; 'äd-'hOk
Function: adverb
Etymology: Latin, for this
: for the particular end or case at hand without consideration of wider application
-
Main Entry: 2ad hoc
Function: adjective
1 a : concerned with a particular end or purpose <an ad hoc investigating committee> b : formed or used for specific or immediate problems or needs <ad hoc solutions>
2 : fashioned from whatever is immediately available : IMPROVISED <large ad hoc parades and demonstrations -- Nat Hentoff>
Taxonomy of Ad Hoc Networks
- The spectrum: Fixed networks <----- vs. -----> ad hoc networks
- Computing device characteristics
- Sessile devices vs. mobile devices
- Wired connectivity vs. wireless connectivity
- Mains powered vs. battery powered
- Network characteristics
- Preexisting infrastructure vs. ad hoc infrastructure
- Routers, access points, DHCP servers, etc. vs. lack thereof
- Seldom varying configuration vs. rapidly varying configuration
- Devices staying in range of the network vs. devices moving in and out of range
- Constant network topology vs. varying network topology
- Devices staying powered on vs. devices turning on and off frequently
- Preplanned configuration vs. ad hoc configuration
- Topology not a complete graph vs. topology a complete graph
- Extended area vs. proximal area
- Packet forwarding (routing) vs. packet broadcasting
- Preexisting infrastructure vs. ad hoc infrastructure
- Application characteristics
- Central server based vs. central serverless (peer-to-peer)
- One-to-one vs. one-to-many vs. many-to-many communication patterns
Issues in Ad Hoc Networks
- The Internet tends to fall at the fixed end of the spectrum along each dimension
- The Internet protocols were designed for the fixed end of the spectrum and tend not to work well at the ad hoc end of the spectrum
- For ad hoc networks, we need new solutions to the issues the Internet addressed
- Network application technology
- Fixed end: Client-server, TCP sockets, distributed object middleware (CORBA, RMI, SOAP, etc.)
- Ad hoc end: Not a lot there! -- Many-to-Many Invocation (M2MI), Tuple Board
- Routing
- Fixed end: Predetermined routes, shortest path algorithms, link state routing, distance vector routing
- Ad hoc end: On-demand routes, Dynamic Source Routing (DSR), Ad Hoc On Demand Distance Vector Routing (AODV), others
- Broadcast and multicast routing
- Network security
- Fixed end: block ciphers, message authentication codes, two-party key exchange, public key ciphers, digital signatures, public key infrastructure (PKI), secure transport protocols (SSL, TLS, HTTPS)
- Ad hoc end: Not a lot there! -- Group key exchange
- Location awareness
- Fixed end: Not a lot there, since devices tend to be sessile
- Ad hoc end: GPS tracking, cellphone tracking, RFID tracking, location-aware content/services/applications
- Energy awareness
- Fixed end: Not a lot there, since devices tend to use "limitless" mains power
- Ad hoc end: Energy aware routing, energy aware applications
- "Moore's Law does not apply to batteries." -- Heard during a presentation at JavaOne 2000.
Applications for Ad Hoc Networks
- Services
- Printers
- Projectors
- Computing grids
- Conversations
- Conversations in quiet spaces
- Conversations in noisy spaces
- Sharing
- Photos (What You See Is What I Get)
- Videos
- MP3s (What You Hear Is What I Get)
- Bulletin boards
Sidney Harris. "You Want Proof? I'll Give You Proof!" W. H. Freeman and Company, 1991.
- Groupware
- Presentations
- Whiteboard
- Note taking
- Document authoring
- Calendar scheduling
- Contact information
- Monitoring, sensor networks
- Fire
- Intruder
- Medical
- Panic buttons
- Battlefield
- Environmental (wildfires, whales)
- Multiplayer games
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