Edexcel GCSE Computer Science (1CP2) Exam Questions

Award up to two marks for a linked description such as:

• The bandwidth/capacity of the access point is shared between all the connected devices (1) so each device gets less bandwidth as more devices connect, which reduces the speed of data transfer (1)
• The devices have to take turns to transmit (contention) (1) so each device waits longer before it can send data, which increases latency (1)
• The access point can only support a maximum number of connections (1) so once this limit is reached, further devices cannot connect to the network (1)

Allow 'contention' as an alternative to devices having to take turns to transmit.

Allow 'the network becomes slower' as the second mark only where it is linked to shared bandwidth, to devices taking turns to transmit or to the maximum number of connections.

Do not accept a response that only states the network becomes slower, or that there are more devices/more traffic, without saying how this affects performance.

Do not accept responses about range or interference unless they are linked to the number of connected devices.

Award up to two marks for a linked description such as:

• Interference from other devices corrupts the wireless signal (1) so the data has to be resent, which increases the delay (1)
• Devices on a wireless network take turns to use the same channel/frequency (1) so a device may have to wait for the channel to be free before it can transmit, which adds to the delay (1)
• Data on a wireless connection must pass through the access point to reach the wired network (1) so the extra processing/conversion at the access point adds a delay (1)

Do not accept responses that only state that a wireless connection is slower/less reliable than a wired connection, without explaining how this adds latency.

Do not accept 'data is sent through the air' on its own, as this does not explain why latency is higher.

Do not accept responses about bandwidth or speed on their own.

Award up to two marks for a linked explanation such as:

• Data can avoid a busy/congested link (1) because the router can choose another path (1)
• Data can still arrive if a link fails (1) because the router sends it another way (1)
• Data can take the shortest/fastest path (1) because the router compares the routes and chooses the one with the fewest hops/least traffic (1)

For both marks, the expansion must follow/associate with the statement.

Allow other valid benefits with a linked reason, e.g. traffic can be shared across routes/load balanced (1) because the router can send some packets by another path (1)

Do not accept 'the route is always the same' as this is not a benefit of choosing a route.

Do not accept 'routers are fast' or 'packets are sent faster' on its own: the reason must say how the route is chosen, e.g. avoiding congestion or using a routing table.