This website houses notes from my studies at the University of Liverpool. If you see any errors or issues, please do open an issue on this site's GitHub.
Guided Transmission Media In addition to the following you can also have transfer through physical media. This can give the best transfer rate (especially for large amounts of data). Twisted Pair You can twist the cables more to give better cross talk. Coaxial Cable - A copper core surrounded by...
The channel capacity can be defined in two different ways: Data Rate: In bits per second. Rate at which data can be communicated. Bandwidth: The frequency width of the transmitted signal. In cycles per second or Hz. Constrained by the transmitter and medium. Nyquist Bandwidth If the bandwidth is $B$,...
Attenuation The received signal must be sufficiently higher than noise to be received without error. Signal amplitude decreases with distance. Depends on the medium. Attenuation is an increasing function of frequency. Delay Distortion This occurs as the velocity of propagation of a signal through a guided medium varies with frequency:...
Sine Waves Sine waves can be made using the following function: \[s(t)=A\sin(2\pi ft+\phi)\] Where: $A$ - Amplitude $f$ - Frequency $t$ - Time $\phi$ - Phase $T$ - Period ($\frac1f$) Any signal can be made of many sine components. Frequency Domain Representation You can plot the frequencies of a periodic...
The Problem You have been contacted to develop a computer system for a university medical clinic. The clinic needs the following types of service: Staff management Booking appointments Keeping records You are asked to build an interactive system which handles all of these aspects online. Developing Requirements We need to...
This lecture is basically a copy of some COMP122 lectures. For more information on any topic, click on the link below: General OOP concepts - Introduction to OOP Objects Classes Constructors Encapsulation Inheritance - Subclasses Dynamic binding is where you write: B temp = new C(); This is where we...
These notes are low-effort, due to catching up in this module. See the videos and slides for more detail. The link layer concerns the links that connect various nodes (hosts and routers) on a network. The link layer only needs to transfer a frame from a node to an adjacent...
These notes are low-effort, due to catching up in this module. See the videos and slides for more detail. Routing Algorithms Routing algorithms choose a sequence of routers for a packet to traverse from source to destination. We can define the cost of a hop by using link costs: graph...
These notes are low-effort, due to catching up in this module. See the videos and slides for more detail. Network Layer The network layer completes two functions: Forwarding - Moving packets from a router’s input link to the appropriate router output link. Routing - Determining the route taken by packets...
These notes are low-effort, due to catching up in this module. See the videos and slides for more detail. You may want a protocol that is tailored to a specific scenario such as: Long fat pipes (many in flight packets). Wireless networks (noisy links with high bandwidth). Long delay links...