1
Q
Data Transmission
A
- Transferring data between two or more devices
2
Q
Serial Transmission
A
- Sends bits one after another over a single channel in order.
- The order sent dictates the order received.
- Used for long-distance data transfer. Data sent is small.
3
Q
Asynchronous Serial Transmission
A
- Stop and start bits in header/footer, Co-ordinate transmitter and receiver.
- Gaps are used between sending bits as data stream is not constant.
- No synchronisation required.
- Cost effective, Slower.
4
Q
Synchronous Serial Transmission
A
- Continuous stream in time with master clock.
- Data moves faster, Less timing errors.
- Accuracy dependent on syncing, Usually more expensive.
5
Q
Parallel Transmission
A
- Multiple bits, same time, diff channels.
- Data can be sent faster.
- Order the bit string received depends on source, user location, and available bandwidth.
- Some bits may be received faster than others, need to be arranged once received.
- Easier to program, For time sensitive data, Large amounts of data.
- Requires more channels, If bits don’t load fast enough noticeable difference.
6
Q
Simplex
A
- One direction.
- Fibre optic cable.
- One device for transmitting, one for receiving.
- Entire bandwidth used.
7
Q
Half Duplex
A
- Both directions, one at a time.
- Simplex with switchable direction.
- Cheaper than double tracks.
8
Q
Full Duplex
A
- Both directions, same time.
- Increases communication efficiency.
- Cable constructed in zipcord style.
9
Q
Multiplexing
A
- Multiple signals sent over a link at the same time.
- Receiver recovers seperate signals. ‘Demultiplexing’.
- Multiplexer divides channel into sub-channels, allocates data into one sub channel. Data is transmitted, and then the demultiplexer receives, identifies, and sends onward.
- Makes it possible for transmission over big networks. Stretches valuable resources.
- Several independent data sources are combined to be sent along a single route to a specific destination.
10
Q
Circuit Switching
A
- Route set up before all packets sent down it.
- Packets arrive in order.
- If one bit breaks all fails.
- Bandwidth not used to full capacity.
11
Q
Packet Switching
A
- Each packet takes different route.
- Resilient to failure.
- Full bandwidth used.
- Packets don’t arrive in order/ Extra processing.
12
Q
Control Data v Actual Data
A
CONTROL:
- Source/Destination address.
- Order number.
- Control signals.
- Error control bits.
- In header/footer of packet.
ACTUAL:
- Message.
12
Q
Network Collision
A
- Two data sets detected simultaneously.
- Both sets discarded, source PC notified they have been.
- Computers wait a random time before sending off packet again.
13
Q
Routing Data
A
- Determines path packet takes.
- Looks for quickest path.
- Calculates lowest cost.
