IGCSE Computer Science 0478: Wireless Access Point and Modem in a Home Network

A family's internet service provider installs a single combined networking box in their living room. Two features of this box are relevant here. First, it lets a phone and a tablet join the home network from anywhere in the house without any cable ever being plugged into them, sending and receiving data as radio signals instead. Second, the box is also wired, by a telephone line running outside the house, to equipment belonging to the internet service provider; along this connection, the box converts the family's outgoing digital data into a signal suitable for transmission down the telephone line, and converts incoming signals from the telephone line back into digital data the home network can use.

(a) Name the piece of network hardware responsible for letting the phone and the tablet join the home network without a cable, and describe what it does. [2]

(b) Name the piece of network hardware responsible for converting the family's data for transmission down the telephone line and converting it back again, and describe what it does. [2]

(c) One evening, the connection along the telephone line to the internet service provider develops a fault, but the box itself is still switched on. State, with a reason, whether the phone would still be able to send a photo directly to the tablet over the home network, and whether it would still be able to load a website from the internet. [2]

Part (a): The wireless access point

The feature that lets the phone and the tablet join the home network without a cable is provided by a wireless access point (WAP). A WAP allows devices with a wireless network interface card to connect to the network by sending and receiving data as radio signals, rather than needing a cable plugged directly into them. This is why the phone and tablet can join the network from anywhere in the house. [2 marks]: [1] for naming the wireless access point, [1] for describing that it allows wireless (radio-signal) connection to the network in place of a cable.

Part (b): The modem

The feature that converts data for the telephone line connection to the internet service provider is provided by a modem (modulator-demodulator). Going out, the modem modulates the family’s digital data into a signal suitable for transmission down the telephone line; coming in, it demodulates the incoming signal from the telephone line back into digital data that devices on the home network can use. This conversion is what allows the home network to communicate with the internet service provider over a connection originally designed to carry telephone calls. [2 marks]: [1] for naming the modem, [1] for describing the modulation/demodulation of data for the telephone line connection.

Part (c): What still works, and what does not, after the fault

Phone to tablet, directly over the home network: still possible. Sending a photo between two devices already on the same home network only relies on the wireless access point, which lets them communicate with each other locally; it does not need the connection to the internet service provider at all.
Loading a website from the internet: not possible. A website is stored outside the home network, so reaching it depends on the modem’s connection along the telephone line to the internet service provider, and that specific connection is the one that has developed the fault.

[2 marks]: [1] for correctly stating the phone-to-tablet transfer would still work, with a valid reason; [1] for correctly stating the website would not load, with a valid reason.

Final answers

(a) Wireless access point (WAP), lets devices connect to the network using radio signals instead of a cable.
(b) Modem, converts data between the digital form used on the network and the signal needed to travel along the telephone line to the internet service provider.
(c) The phone-to-tablet transfer would still work (local, via the WAP); loading a website would not work (depends on the modem’s now-faulty connection to the ISP).