Cellular networks (4G, 5G) in Computer Networks - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding 4G LTE Technology

Which of the following best describes the main improvement 4G LTE brought compared to 3G networks?

A It increased data speeds and enabled IP-based communication.

B It introduced packet switching for voice calls only.

C It replaced all radio towers with satellite communication.

D It focused solely on improving battery life of devices.

💡 Hint

Think about what 4G LTE improved most for internet and communication.

4G LTE mainly improved data speeds and shifted communication to IP-based systems, unlike 3G which was more circuit-switched.

📋 Factual

intermediate

5G Frequency Bands

Which frequency range is commonly used by 5G networks to achieve very high data rates but with limited coverage?

A Millimeter wave bands above 24 GHz

B Mid-band frequencies around 2-6 GHz

C Below 100 MHz bands

D Sub-1 GHz bands

💡 Hint

Consider which frequencies allow very fast data but don't travel far.

Millimeter wave bands above 24 GHz offer very high data rates but have limited range and penetration.

🔍 Analysis

advanced

Comparing 4G and 5G Latency

Given that 4G networks typically have latency around 50 milliseconds and 5G aims for latency as low as 1 millisecond, what is the practical impact of this reduction?

A It only improves battery life of mobile devices.

B It enables near real-time communication suitable for applications like remote surgery and autonomous driving.

C It allows for faster web page loading but no change in real-time applications.

D It increases the maximum number of connected devices but does not affect speed.

💡 Hint

Think about applications that need very fast response times.

Lower latency in 5G enables applications requiring near real-time responses, such as remote surgery and autonomous vehicles.

❓ Reasoning

advanced

5G Network Architecture Benefits

Which feature of 5G network architecture helps it support diverse use cases like IoT devices, enhanced mobile broadband, and ultra-reliable low latency communication?

A Replacing all base stations with Wi-Fi hotspots.

B Use of a single fixed frequency band for all services.

C Network slicing that creates multiple virtual networks on the same physical infrastructure.

D Limiting the number of connected devices to reduce congestion.

💡 Hint

Consider how one network can serve very different needs simultaneously.

Network slicing allows 5G to create multiple virtual networks tailored for different services on the same hardware.

❓ Comparison

expert

Impact of Massive MIMO in 5G

Massive MIMO (Multiple Input Multiple Output) is a key technology in 5G. What is its main advantage compared to traditional MIMO used in 4G?

A It only improves voice call quality without affecting data transmission.

B It uses fewer antennas to reduce hardware costs but lowers data rates.

C It replaces antennas with satellite links for better global coverage.

D It uses a large number of antennas to improve capacity, coverage, and spectral efficiency significantly.

💡 Hint

Think about how adding more antennas affects signal quality and capacity.

Massive MIMO uses many antennas to send and receive multiple data streams simultaneously, greatly improving network performance.

Practice

1. What is the main advantage of 5G over 4G in cellular networks?

easy

A. Faster speeds and lower delay

B. Longer battery life for devices

C. Better voice call quality only

D. Uses older technology standards

Solution

1. Step 1: Understand 4G and 5G basics

   4G provides fast internet and good connectivity for most uses.

2. Step 2: Compare 5G features

   5G improves speed significantly and reduces delay (latency), allowing more devices to connect smoothly.

3. Final Answer:

   Faster speeds and lower delay -> Option A

4. Quick Check:

   5G speed & latency = Faster and lower [OK]

Hint: 5G is about speed and delay, not just calls [OK]

Common Mistakes:

• Thinking 5G only improves call quality
• Confusing battery life improvements with network speed
• Assuming 5G uses older technology

2. Which of the following is the correct way to describe 4G technology?

easy

A. A wired internet connection

B. A type of computer processor

C. A wireless network technology for mobile devices

D. A software application for phones

Solution

1. Step 1: Identify 4G technology type

   4G is a wireless network technology that connects mobile devices to the internet.

2. Step 2: Eliminate incorrect options

   It is not wired, not a processor, and not software but a network standard.

3. Final Answer:

   A wireless network technology for mobile devices -> Option C

4. Quick Check:

   4G = Wireless network tech [OK]

Hint: 4G connects phones wirelessly, not wired [OK]

Common Mistakes:

• Confusing 4G with hardware components
• Thinking 4G is software
• Assuming 4G means wired internet

3. Consider this code snippet simulating network speed check:

network = "5G"
speed = 1000 if network == "5G" else 100
print(speed)

What will be the output?

medium

A. 100

B. 1000

C. network

D. Error

Solution

1. Step 1: Check the network variable value

   The variable network is set to "5G".

2. Step 2: Evaluate the conditional expression

   Since network == "5G" is true, speed is assigned 1000.

3. Final Answer:

   1000 -> Option B

4. Quick Check:

   network == "5G" -> speed = 1000 [OK]

Hint: Check condition true? Then speed = 1000 [OK]

Common Mistakes:

• Assuming speed is 100 by default
• Confusing variable names with output
• Expecting syntax error due to inline if

4. This code tries to print the network type but has an error:

network = 4G
print(network)

What is the error and how to fix it?

medium

A. No error, code runs fine

B. print() function is missing parentheses

C. Variable name 'network' is invalid

D. 4G should be in quotes to be a string

Solution

1. Step 1: Identify the error in variable assignment

   4G is not in quotes, so Python treats it as a variable, causing an error.

2. Step 2: Fix by adding quotes

   Put "4G" in quotes to make it a string: network = "4G".

3. Final Answer:

   4G should be in quotes to be a string -> Option D

4. Quick Check:

   Strings need quotes in Python [OK]

Hint: Strings must be in quotes to avoid errors [OK]

Common Mistakes:

• Forgetting quotes around text
• Thinking print() needs no parentheses
• Assuming variable names can't be 'network'

5. A city wants to upgrade its cellular network to support many smart devices with very low delay. Which technology should they choose and why?

hard

A. 5G, because it supports more devices and has lower latency

B. 4G, because it is widely available and fast enough

C. 3G, because it uses less power

D. Wi-Fi, because it covers large outdoor areas

Solution

1. Step 1: Understand the city's needs

   The city needs to support many smart devices with very low delay (latency).

2. Step 2: Compare network technologies

   4G is fast but 5G supports many more devices simultaneously and has much lower latency. 3G is outdated and Wi-Fi does not cover large outdoor areas well.

3. Final Answer:

   5G, because it supports more devices and has lower latency -> Option A

4. Quick Check:

   Many devices + low delay = 5G [OK]

Hint: More devices + low delay = choose 5G [OK]

Common Mistakes:

• Choosing 4G for large device support
• Confusing Wi-Fi coverage with cellular
• Picking older 3G technology