1. CDA6530: Performance Models of Computers and Networks Project 3 Q&A
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2. Structure definition in Matlab:
m = 300; n =300;
Structure definition in Matlab:
Node=struct('status', zeros(m,n), 'infectTime', zeros(m,n), 'InfectOtherTime', zeros(m,n));
Or you can define:
NodeState = zeros(m,n);
NodeInfectTime = zeros(m,n);
NodeInfectOtherTime = zeros(m,n);

3. Multiple Way to Remember Infection Traffic
Define a queue variable to remember:
Generated infection traffic source (or destination)
Active time (when the source passes the traffic to all its neighbors, or when a vulnerble node receives the traffic)
Quite complicated since the event queue is very dynamic

4. Multiple Way to Remember Infection Traffic (my approach)
Use each infected node variable to remember when its outgoing infection traffic reach its neighbors
NodeInfectOtherTime(i,j) save the time for infection traffic reaching the node(i,j)’s neighbors

5. How to determine neighboring nodes?
You don’t need the code to remember the topology since it is so regular
Node(a,b)’s 4 neighbors:
Upper node: (a-1,b), Down node: (a+1, b)
Left node: (a,b-1), right node: (a, b+1)
Make sure you check if any of the above 4 nodes are non-exist
For S2, you also need to check if the node is one of those 10 shortcut nodes
If yes, considering the 5th neighboring node

6. How to decide the simulation end time?
At current discrete time k, check all nodes:
If all (NodeInfectOtherTime(.,.) < k), then stop
It means there does not exist any future infection traffic anymore

7. Infection Activity from sending node angle
At current time t:
If the NodeState(j,k) == ‘infected’
If the NodeInfectOtherTime(j,k) == t,
%the node infection traffic reach its neighbors now!
Check all its neighbors to see if any neighbor is infected now, if the neighbor node(a, b) is infected now:
NodeState(a,b) = infected;
NodeInfectTime(a,b) = t;
generate Poisson distr. delay time x;
NodeInfectOtherTime(a,b) = x +t +1;
If NodeState(j,k) == ‘vulnerable’
Do nothing

8. Two Actions for Every Infected Node
Act 1: when node(a,b) becomes infected at current discrete time t
Change its status: NodeState(a,b) = INFECTED;
Assign:
NodeInfectTime(a,b) = t;
x = PoissonGenerator();
NodeInfectOtherTime(a,b) = t + x + 1;
Act 2: when an infected node delivers infection traffic to its neighbors
When? if (NodeState(a,b) == INFECTED &&
t == NodeInfectOtherTime(a,b) )
Check each of its neighbor:
If neighbor node(c,d) is vulnerable and will be infected?
Run Act 1 for the node(c,d)

9. startTime = cputime;
Simulation….
simulateCPUTime = cputime – startTime;