An office wireless network is near a microwave oven and several other wireless networks.
Explain how interference can affect the speed of a wireless network.
Mark scheme
Award up to two marks for a linked explanation such as:
- The speed of data transfer is reduced/is slower (1) because interference corrupts the radio signal, so data/packets are lost and have to be resent/retransmitted (1)
- The network speed is lower (1) because there is more noise on the wireless signal, so data is sent at a lower transmission rate (1)
- The throughput of the wireless network is reduced (1) because time is used resending corrupted data/packets instead of sending new data (1)
For both marks, the expansion must follow/associate with the statement.
Award 1 mark for a statement that the speed/transfer rate is reduced (e.g. slower, takes longer), even if no reason is given.
Do not accept 'interference damages/corrupts the radio signal' or 'the signal is weaker' on its own without a link to the speed.
Do not accept 'data is lost' on its own without saying how this reduces the speed.
Do not accept 'interference increases the bandwidth' or 'interference makes the signal stronger'.
Example answers and how they were marked
Interference corrupts the radio signal, so packets are lost and resent, which makes the data transfer slower.
Why: Linked point (1): data transfer is slower; reason (1): interference corrupts the signal so packets are lost and resent.
The speed of the wireless network will be lower.
Why: Point only (1): states the effect on speed. No linked reason why interference causes this.
Interference increases the bandwidth, so the data travels faster.
Why: Misconception that interference increases bandwidth; the mark scheme says not to accept this.