Key terms
Make sure you can explain each of these in your own words. The glossary has short definitions.
- Protocol
- simplex
- half-duplex
- full-duplex
- modulation
- bandwidth
- throughput
- latency
- jitter
- CRC
- multiplexing
- packet switching
Self-check questions
Write your answers first, then open the answers to check them.
- List the five components of a data communication system.
- Which transmission mode does modern switched Ethernet use, and why is it better than half-duplex?
- Why is optical fibre preferred for backbone links?
- A 25 MB file is sent over a 50 Mbps link. How long does it take in the ideal case?
- State one difference between circuit switching and packet switching.
Show answers
Message, sender, receiver, transmission medium, protocol.
Full-duplex, so that both devices can send and receive at the same time and no collisions occur, giving higher effective throughput.
Very high bandwidth over long distances with low signal loss and immunity to electromagnetic interference.
25 MB = 200 Mb; 200 / 50 = 4 seconds.
Circuit switching reserves a dedicated path for the whole communication; packet switching splits data into packets that share the network and may take different routes.
Next: when you are confident with this unit, test yourself with the multiple-choice questions for Unit 1 in the Final Revision section.