Transcript Document

PRoPHET with LEGO Mindstorms
The Goal of the Project
The task in this project is to implement the PRoPHET (Probabilistic Routing Protocol using History of Encounters and
Transitivity) and Epidemic routing protocol for the LEGO Mindstorms platform (RCX), and then do a comparison between
the two protocols by evaluating the results from our test runs. The LEGO robots will act as nodes in an intermittently
connected network.
PRoPHET
Epidemic Routing
PRoPHET is a routing protocol for intermittently
connected networks. In such networks there are no
guarantees that a fully connected path between the
sources and the destinations exists at all time. To send
messages through these kind of networks, PRoPHET
uses a probability function to determine which path the
packet should choose.
Epidemic is a simple routing protocol for intermittently
connected networks. It basically forwards all messages
to all node it meets, hence flooding the network. When
the receive buffer is full it will write over the old
messages.
Test setup
About LEGO Mindstorms
Lego Mindstorms are the next generation of LEGO.
Simply it is a microcomputer where you can connect
different devices, such as motors, light sensors, triggers.
It’s also capable of transmitting and receiving IR (infra
red), which is vital to this project, since we want to send
and receive data from the different nodes in the network.
The robots are kept inside areas, where they are
supposed to communicate with their neighbours when
an opportunity arise.
Id 3
Id 4
Id 5
The internal memory in the Robot is 32Kb.
Id 1
Id 2
The Robots has an OS called BrickOS, which is an
alternative operating system for the Lego Mindstorms
(RCX). It provides a C/C++ development environment
for RCX.
Id 6
Results
The results are derived from the data collected through
our test runs. Below are two diagrams showing how the
two protocols compare with respect to delivery ratio and
average sent messages per node.
The tables below show the probability from a specific
node to the other nodes calculated by PRoPHET from
some of our test runs.
Average sent m essages per node
Average Delivery Ratio
Node Id1
Id2: 0.5743
Id3: 0.1644
Id4: 0.0697
Id5: 0.2344
Id6: 0.1178
Node Id2
Id1: 0.5965
Id3: 0.3659
Id4: 0.1679
Id5: 0.5881
Id6: 0.2700
Node Id3
Id1: 0.0901
Id2: 0.2999
Id4: 0.3601
Id5: 0.3634
Id6: 0.1404
Node Id4
Id1: 0.0406
Id2: 0.0915
Id3: 0.2931
Id5: 0.2057
Id6: 0.0741
Node Id5
Id1: 0.2532
Id2: 0.5144
Id3: 0.5466
Id4: 0.2992
Id6: 0.6054
Node Id6
Id1: 0.1422
Id2: 0.2623
Id3: 0.2394
Id4: 0.1912
Id5: 0.5763
25
80
20
60
50
PROPHET
40
Epidemic
30
Messages
Delivery ratio (%)
70
15
PROPHET
Epidemic
10
20
5
10
0
0
5
8
Buffer Size
11
0
5
8
11
Buffer Size
The left diagram clearly shows PRoPHET having a
higher delivery rate than Epidemic when buffer size is
limited. The right diagram shows that PRoPHET is also
utilizing less resources.
Members
Patrik Vesterlund
Andreas Browall
Jonas Frisk
Supervisors
Anders Lindgren
Kaustubh Phanse
Pontus Johansen