• Protocol 5.4: Greedy georouting protocol

    PROTOCOL

    Greedy georouting protocol

    SUMMARY

    The purpose of Greedy Georouting is to relay a message between two motes on the same network. After the source and sink mote have been selected, the source mote is given the coordinates of the sink mote. The source mote then sends the message to the neighbor with the closest Euclidean distance to the sink mote. This continues until the message has been relayed to the sink mote.

    OPERATION

    • Click the Setup button to generate a network based on communication distance and network size.
    • Click the Go! button to run the algorithm.

    NOTICE

    • The source mote is yellow and the sink mote is red. Both are larger than the other motes.
    • The message path is thick and orange in color.
    • Use the MoteLabel list to change the labels to the mote id.

    TRY

    • What happens if the communication distance is too small, making a disconnected network? Does the algorithm still route the message? Change this by adjusting the c slider.
    • Try selecting GG or RNG from the NetworkStructure drop-down box to change the network shape to a Gabriel Graph or Relative Neighborhood Graph. Does the algorithm run any differently?
    • Try running the algorithm slowly to get a better idea of how the algorithm runs. Change this by adjusting the speed slider.

    LINK TO BOOK

    Protocol 5.4

    CREDITS

    Code designed by Matt Duckham. Additional coding by Alan Both.

    LICENSE

    Copyright 2011, 2012 Matt Duckham

    This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License http://www.gnu.org/licenses/ for more details.

    Protocol 5.3

    The formal specification procedure used for all the protocols on this site is based on the standard distributed systems approach of Nicola Santoro (see Santoro, N. Design and Analysis of Distributed Algorithms. Wiley, Hoboken, NJ. 2007.) For more details on the protocol specification style, please refer to the book accompanying book for this website, Decentralized Spatial Computing: Foundations of Geosensor Networks.

    ;;  Copyright 2011, 2012 Matt Duckham
    ;;
    ;;  This program is free software: you can redistribute it and/or modify
    ;;     it under the terms of the GNU General Public License as published by
    ;;     the Free Software Foundation, either version 3 of the License, or
    ;;     (at your option) any later version.
    ;;
    ;;     This program is distributed in the hope that it will be useful,
    ;;     but WITHOUT ANY WARRANTY; without even the implied warranty of
    ;;     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ;;     GNU General Public License for more details.
    ;;
    ;;     You should have received a copy of the GNU General Public License
    ;;     along with this program.  If not, see <http://www.gnu.org/licenses/>.
    
    __includes["../gsn.nls"]
    ;; Define a new breed of turtle called motes
    breed [motes mote]
    
    ;; Each mote can store the local variables m which is the message, N which is the set of
    ;; neighbor locations and d which is the coordinates of the sink mote.
    motes-own [m N d]
    
    ;; System setup and initialization
    to initialize
      if NetworkStructure = "UDG" [create-udg] ;; Create UDG network
      if NetworkStructure = "GG"  [create-udg create-gg] ;; Create GG network
      if NetworkStructure = "RNG" [create-udg create-rng] ;; Create RNG network
      ask motes [
        set N []
        become "IDLE" ;; Set all motes to state IDLE
      ]
      let sink one-of motes ;; Selecting the sink mote
      ask sink [
        set color red
        set size (size * 1.5) ;; The sink mote is larger than other motes
      ]
      ask one-of motes [ ;; Selecting the source mote
        set size (size * 1.5) ;; The source mote is larger than other motes
        set m "'Hello!'"
        become "SEND"
        set color yellow
        set d (list [xcor] of sink [ycor] of sink) ;; Setting destination coordinates
      ]
    end
    
    ;; Runs the greedy georouting algorithm
    to go
      ask motes [ step ]
      mote_labels ;; Changes the labels of the motes based on the MoteLabel dropdown list
      tick
    end
    
    ;;
    ;; Mote protocols
    ;;
    
    ;; Step through the current state
    to step
      if state = "SEND" [ step_SEND stop ]
      if state = "IDLE" [ step_IDLE stop ]
      if state = "LSTN" [ step_LSTN stop ]
    end
    
    ;; Sends a PING message to neighbors, then transitions into the LSTN state.
    to step_SEND
      broadcast (list "PING") ;; Broadcast 'ping' to neighbors
      become "LSTN" ;; Change state to listen for responses to 'ping'
    end
    
    ;; Motes in the IDLE state respond to a PING message by sending back their coordinates 
    ;; and respond to a MSGE message by determining if it is the sink mote. If it is, it
    ;; shouts the relayed message. If it isn't, it stores the message and destination
    ;; coordinates and transitions into the SEND state.
    to step_IDLE
      if has-message "PING" [ ;; Receiving PING message
        let msg received "PING"
        let p (list xcor ycor)
        broadcast (list "POSN" p) ;; Broadcast location in response to 'ping' message
        stop
      ]
    
      if has-message "POSN" [ ;; Ignore POSN message
        let msg received "POSN"
        stop
      ]
    
      if has-message "MSGE" [ ;; Receiving MSGE message
        let msg received "MSGE"
        let m' item 1 msg
        let d' item 2 msg
        ifelse (list xcor ycor) = d' [ ;; Check if this node location is the destination for this message
          show (word "Message " m' " received!") ;; The message has been successfully received at the destination
          become "DONE"
        ]
        [
          set m m' ;; Store the message and the destination
          set d d'
          become "SEND"
        ]
        stop
      ]
    end
    
    ;; Motes in the LSTN state wait until they have received POSN messages from all of its
    ;; neighbors. They then determine the neighbor with the closest Euclidean distance to the
    ;; sink mote. It then sends the relayed message to that neighbor.
    to step_LSTN
      if has-message "POSN" [ ;; Receiving POSN message
        let msg received "POSN"
        let l item 1 msg
        set N fput l N ;; Store received neighbor location
        if length N = count link-neighbors [ ;; Check if messages received from all neighbors
          let min-dist 1000000 ;; Arbitrarily large initial distance
          let min-loc []
          foreach N [
            let n' ?
            if min-dist > dist n' d [ ;; Find closest neighbor
              set min-dist dist n' d
              set min-loc n'
            ]
          ]
          send (list "MSGE" m d) one-of motes with [(list xcor ycor) = min-loc] ;; Forward message to next neighbor
          ask link-with one-of motes with [(list xcor ycor) = min-loc] [
            set color orange
            set thickness 0.15
          ]
          become "IDLE"
        ]
        stop
      ]
    end
    
    ;; Changing the labels of the motes based on the MoteLabel dropdown list
    to mote_labels
      ask motes [
        if MoteLabel = "none" [set label ""] ;; Hide the label
        if MoteLabel = "mote id" [set label who] ;; Show mote id
      ]
    end
    

    The NetLogo procedures for this applet can be downloaded directly as: Protocol5.3.nlogo

    All the NetLogo simulation models for this book depend on two library files: gsn.nls and env.nls
    These files should be placed in the parent directory of the .nlogo file (and are common to all the .nlogo models on this website).

Leave a Reply

Your email address will not be published. Required fields are marked *

*

* Copy this password:

* Type or paste password here:

8,281 Spam Comments Blocked so far by Spam Free Wordpress

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>