9 Communication and networks

Synchronous transmission (2 + 1)

• Receiver and transmitter are continually synchronised by a common clock

• Timing information is transmitted within/alongside the data

• (used for internal data buses)

Asynchronous transmission (2 (3))

• Receiver’s clock is synchronised to transmitter’s each time a start bit is received

• Once the stop bit is received

  • the transmission stops

  • time is provided for the receiver to process

  • the next start bit is able to be recognised

Bit rate

The number of bits transmitted per second.

Baud rate

The rate at which signals on a wire or line can change.

Bandwidth

The range of signal frequencies that a transmission medium can transmit without a significant reduction in signal strength.

Latency

The time delay between the moment the first data packet of a communication starts and when it is received at its destination.

Bit Rate and Bandwidth relationship

Directly proportional

Bit rate vs Baud rate magnitude

Bit rate can be higher than baud rate if more than one bit is encoded in each signal change.

Serial transmission

Sends one bit at a time down a single wire

Parallel transmission

Sends multiple bits at the same time using multiple wires (each bit is sent down a different wire)

Serial vs Parallel Transmission

2. Pros of Serial (Cons of Parallel):

• 💰 Cost: The hardware/wiring required for serial is cheaper.

• 📶 Interference: No crosstalk. Bits cannot interfere with each other because they are not sent simultaneously.

• 🎯 Accuracy: No data skewing. Bits are guaranteed to arrive in the exact order they were sent.

• 📏 Distance: Reliable over longer distances (Parallel is only reliable over very short distances).
  

3. Cons of Serial (Pros of Parallel):

• 🐢 Throughput: Serial can only send one bit at a time per clock cycle, whereas Parallel has the advantage of sending multiple bits exactly at the same time.

Protocol

A set of rules relating to communication between devices.

Flashcards needed on

Everything in the mind map (e.g.): All of networks