Telecommunications

In all communication, there are three parts: the one sending (sender), the path through which the signal travels (medium), and the one receiving it (receiver). Identify these three parts in each situation: (a) sending a message on a mobile phone; (b) watching a video on a laptop; (c) playing online on a console.

The figure shows the diagram of any communication: a sender transmits a message that reaches a receiver, but the central element is covered with a question mark, as shown in the diagram.

Which element of the diagram is covered? Give two examples of this element, one wired and one wireless, and explain what would happen to the message if that element disappeared.

Classify these transmission media into "wired" and "wireless": twisted pair, Wi-Fi, fibre optic, Bluetooth, coaxial cable, 4G mobile networks. Explain in one sentence what difference there is between the two groups.

Fibre optics have replaced old copper ADSL in many homes. Explain the difference between transmitting information as light pulses or as electric current, and reason why fibre achieves much higher speeds and degrades less over distance.

True or false? Justify each answer: (a) fibre optics transmit information as light pulses; (b) Bluetooth is designed for very short distances; (c) Wi-Fi travels through the air as radio waves; (d) the television remote control can work from kilometres away.

Match each device to the medium it uses to communicate: (a) the TV remote control, (b) wireless headphones, (c) your mobile phone when you are out on the street, (d) the classroom computer connected to the router. Media: 1. Bluetooth; 2. infrared; 3. network cable (twisted pair); 4. 4G or 5G mobile network.

Order these media from shortest to longest typical range and explain the criterion you followed: infrared, satellite, Wi-Fi, Bluetooth, 4G mobile networks.

When subscribing to an internet connection "of $600$ megs", those megs are megabits per second ($\text{Mbps}$). Using the analogy of a pipe or a road, explain what it means for one connection to have more megs than another and what a family notices when using it.

Connections advertise a download speed and an upload speed. Explain what downloading and uploading data mean, and give an everyday example of each action: one where you use downloading and another where you use uploading.

The figure compares typical speeds of four transmission media, as shown in the chart.

Order the four media from slowest to fastest and choose the most suitable one for each situation, justifying your choice: (a) wireless headphones; (b) watching a high-quality film; (c) a home desktop computer; (d) a mobile phone on the bus. Notice that the Bluetooth bar is barely visible: what does that tell you about what that medium is used for (and what it is not)?

Your family pays for $300\ \text{Mbps}$ fibre, but the speed test shows $280\ \text{Mbps}$ with the computer connected by cable and only $60\ \text{Mbps}$ with the laptop on Wi-Fi at the back of the house. Analyse where those megs are "lost" and suggest two ways to recover them.

In a home there is $600\ \text{Mbps}$ fibre, but the computer in the attic, connected via Wi-Fi, only reaches $30\ \text{Mbps}$. Analyse where the bottleneck is (the fibre or the wireless link?) and suggest two different technical solutions (wiring the room, installing an access point, or a Powerline/PLC adapter using the electrical installation), comparing them.

A video game takes up $60\ \text{GB}$ and your connection downloads at $100\ \text{Mbps}$. Remember that $1$ byte is $8$ bits: first convert megabits per second to megabytes per second, then calculate the theoretical download time of the game (use the school convention $1\ \text{GB} = 1024\ \text{MB}$), and explain why in reality it will take somewhat longer.