Trickle Simulation Project Solution

Trickle




Trickle is an algorithm used for propagating and maintaining code updates in wireless sensor net-works (WSNs). Code updates are important in WSNs for several reasons: (i) the requirements of the applications have changed and parameters need to be updated for optimal operation or (ii) a bug has been discovered which needs to be patched. However, energy is a primary driver in the design of WSNs protocols. Code propagation is an expensive process: (i) the size of the code may be large, requiring several messages, (ii) all nodes need to receive the new code and (iii) there may be many redundant messages on the network, and (iv) learning when to propagate the update is important.




Trickle uses techniques from the epidemic, scalable multicast and wireless broadcast research areas. To regulate itself, Trickle uses a technique, called \polite gossip" to exchange code metadata. Trickle has to balance between propagation speed and maintenance cost, and achieves that through several parameters. The parameters are: (i) a counter c, (ii) a redundancy constant k, and (iii) a gossiping interval . We call the tuple (c; k; ) a Trickle tuple and a given value assignment to the Trickle tuple is called a Trickle con guration. Trickle exists as a standard library in the Contiki Operating System.




You will need to read the paper about Trickle, which is available for download from the module webpage.




Coursework




You are required to run a number of simulations to understand the relationship between these Trickle parameters. You will generate a network of 64 nodes and you will need to vary either the distance between the nodes or the transmit power to generate two di erent network topologies, namely a dense network and sparse network. You are allowed to use the existing implementation of Trickle in Contiki.




You will write a sensor network application in Cooja, a wireless sensor network simulator for Contiki. The application will drive the use of Trickle. For each experiment, you will choose a certain number of nodes, ranging from 1 to 5. We call these nodes proposers. Each proposer will propose a value in the range 1 : : : 100. Each proposer will then disseminate its proposed value using Trickle. At the end of the dissemination process, every node will evaluate the average of the values that have been proposed. So, for example, if there are 4 proposers P1 : : : P4, and P1 proposes 50, P2 proposes 60, P3 proposes 40 and P4 proposes 70, then every node needs to return 55, which is the average of the 4 proposed values. You may need to have a few runs to determine the time taken for the execution to complete and use this as an approximation of the time it will take for the dissemination to complete.




You will produce the following set of plots for the above program:




 
Node id (X-axis) v/s computed average value (Y-axis), for a given Trickle con guration and a given number of proposers. You are to produce the plot for 4 di erent Trickle con gurations for a single topology of your choice.




 
Network diameter v/s Dissemination latency, for a given Trickle con guration and a given number of proposers. You are to produce the plot for 4 di erent Trickle con gurations and for both topologies.




 
Number of proposers v/s number of messages, for a given Trickle con guration. You are to produce the plot for 4 di erent Trickle con gurations. You will also need to show for both topologies




 
Number of proposers v/s dissemination latency, for a given Trickle con guration. You are to produce the plot for 4 di erent Trickle con gurations. You will also need to show for both topologies




The following are the de nitions for the above metrics:




1. Network diameter: Maximum path length between any pair of nodes in the network.






 
Dissemination latency: Miminum time taken for all the nodes to compute the correct average.




 
Number of messages: The total number of message transmissions in the network, by all nodes.




 
Number of messages per node: Number of messages/ number of nodes.




Deliverables




You will submit the following via Tabula, as a zip le, by Monday 4th March at 12pm:




 
A pdf report, of no more than 6 pages. You will explain the working of Trickle in your own words (around half a page). You will explain your experimental setup in detail, e.g., what Trickle con gurations have been used, and discuss the results/plots that you obtain. You will have a short Discussion section in your report where you discuss whether the results you have obtained match those expected of Trickle.




 
A readme le, to explain how to run your experiments.




 
Any piece of code that you write, e.g., scripts, protocol changes etc.




Mark Breakdown




The coursework is worth 40% of the module mark. The mark allocation for each component of your submission will be as follows:




Table 1: Mark breakdown




Component
% Mark








Trickle explanation
10%




Experimental setup
20%




Each set of plots * 4
10%*4=40%




Discussion
5%








Application code
20%




Code compilation & execution
5%








Total
100%
















Important Information



The nature of this project is such that it will not be possible for a student to nish this in one week, as running wireless sensor networks simulations takes time. It is thus advised that students start the project early and plan ahead to ensure the project is successfully completed.

























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