Monday, October 21, 2013

principles of communications, 2013/2014, end of week #2, to L7

To note for today- the slide on graphs, with Edge and Node list has a list of all edges, alongside o nthe right list of nodes  - the list of nodes isn't meant to line up with the list on the left - its just a list for node i=1-5, what other nodes, in the directed graph,  are adjacent (look at arrows on edges - note in 2 cases (1<->2 and 5<->4, they are bi-directional)....

fun references today:-
Ghost Maps




Small Worlds...

DDOS visualised

Couple more corrigenda/errata
1. in the alpha/beta models of random graphs, there's k used for average degree of the net (e.g. pN in the alpha model), but also used for the toal number of edges (N*(N-1)/2) - so take care with k
2. there's an expression in the slides about max-flow in DAR (the "Sticky Random Routing" for the telephoen net) for using Erlang's call blocking probability for a given link, then work out what the toal capacity will be for 1 hop and 2-hop/tandem routes - this has n, which is number of calls you get through, then mentioned a technique called LP  to solve the maximisation problem given in terms of sum of calls that get through (or are blocked) over all direct and tandem routes- we are'nt covering that technique this year, but LP stands for Linear Programming, and is fairly straightforward if you want to look it up - it is commonly used in optimisation and shows up in Operations research/Logistics (freight etc) and so on all the time.

Friday, October 18, 2013

principles of communications, 2013/2014, end of week #1, to L4

We have now covered Systems, and Layers (lawyers)...

Next week, Graphs, and Routes!

Friday, October 11, 2013

principles of communications, 2013/2014, L1

Today this course starts: principles of communcations

This blog will be where I put errata, answers to questions, and just generally track progress of where we've got to for students and supervisors....

Today [11.10.13] got as far as 1/2 way through Systems lecture - Monday
intend to finish that and go about 1/2 way through Layers material: