Multiplexing techniques in Computer Networks - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the multiplexing technique that divides the channel by time slots.

Computer Networks

The multiplexing technique that divides the channel by time slots is called [1].

Drag options to blanks, or click blank then click option'

ATime Division Multiplexing

BFrequency Division Multiplexing

CWavelength Division Multiplexing

DCode Division Multiplexing

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing TDM with Frequency Division Multiplexing which divides by frequency bands.

Choosing Wavelength Division Multiplexing which is used in fiber optics.

Time Division Multiplexing (TDM) divides the channel into time slots, allowing multiple signals to share the same frequency channel by taking turns in time.

2fill in blank

medium

Complete the code to identify the multiplexing technique that uses different frequency bands for each signal.

Computer Networks

The multiplexing technique that assigns different frequency bands to each signal is called [1].

Drag options to blanks, or click blank then click option'

ATime Division Multiplexing

BFrequency Division Multiplexing

CCode Division Multiplexing

DStatistical Multiplexing

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up FDM with TDM which separates by time.

Choosing Statistical Multiplexing which is dynamic allocation.

Frequency Division Multiplexing (FDM) divides the total bandwidth into frequency bands, each carrying a separate signal simultaneously.

3fill in blank

hard

Fix the error in the statement describing the multiplexing technique that uses unique codes for each signal.

Computer Networks

The multiplexing technique that uses unique codes to separate signals is called [1].

Drag options to blanks, or click blank then click option'

ACode Division Multiplexing

BTime Division Multiplexing

CFrequency Division Multiplexing

DWavelength Division Multiplexing

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing CDM with FDM or TDM.

Choosing Wavelength Division Multiplexing which is for fiber optics.

Code Division Multiplexing (CDM) assigns unique codes to each signal so they can be transmitted simultaneously over the same frequency band.

4fill in blank

hard

Fill both blanks to complete the dictionary comprehension that maps multiplexing techniques to their main characteristic.

Computer Networks

multiplexing = {"TDM": "[1]", "FDM": "[2]"}

Drag options to blanks, or click blank then click option'

ATime slots

BFrequency bands

CUnique codes

DWavelengths

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the characteristics of TDM and FDM.

Using codes or wavelengths incorrectly here.

TDM uses time slots to separate signals, while FDM uses frequency bands.

5fill in blank

hard

Fill all three blanks to complete the dictionary comprehension that maps multiplexing techniques to their main characteristic and example.

Computer Networks

multiplexing = {"CDM": "[1]", "WDM": "[2]", "Statistical": "[3]"}

Drag options to blanks, or click blank then click option'

AUnique codes

BWavelengths

CDynamic allocation

DTime slots

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing WDM with FDM or TDM.

Mixing up statistical multiplexing with fixed time or frequency division.

CDM uses unique codes, WDM uses wavelengths in fiber optics, and Statistical Multiplexing uses dynamic allocation of bandwidth.

Practice

1. What is the main purpose of multiplexing in communication systems?

easy

A. To allow multiple signals to share a single communication channel

B. To increase the power of a single signal

C. To encrypt data for secure transmission

D. To convert analog signals to digital signals

Solution

1. Step 1: Understand the concept of multiplexing

   Multiplexing is a technique used to combine multiple signals so they can share one communication channel efficiently.

2. Step 2: Identify the main purpose

   The main goal is to use the channel efficiently by allowing many signals to use it simultaneously, not to increase power, encrypt, or convert signals.

3. Final Answer:

   To allow multiple signals to share a single communication channel -> Option A

4. Quick Check:

   Multiplexing = sharing channel [OK]

Hint: Multiplexing means many signals, one channel [OK]

Common Mistakes:

• Confusing multiplexing with encryption
• Thinking multiplexing increases signal power
• Mixing multiplexing with signal conversion

2. Which of the following is the correct abbreviation for Time Division Multiplexing?

easy

A. TDM

B. FDM

C. WDM

D. CDM

Solution

1. Step 1: Recall common multiplexing abbreviations

   Time Division Multiplexing is abbreviated as TDM, Frequency Division Multiplexing as FDM, Wavelength Division Multiplexing as WDM, and Code Division Multiplexing as CDM.

2. Step 2: Match abbreviation to full form

   Since the question asks for Time Division Multiplexing, the correct abbreviation is TDM.

3. Final Answer:

   TDM -> Option A

4. Quick Check:

   Time Division Multiplexing = TDM [OK]

Hint: T for Time in TDM helps remember [OK]

Common Mistakes:

• Mixing TDM with FDM
• Confusing WDM with CDM
• Assuming CDM stands for Time Division

3. Consider a communication system using Frequency Division Multiplexing (FDM) with 3 channels at frequencies 100 MHz, 110 MHz, and 120 MHz. Which statement is true?

medium

A. Channels transmit one after another in time slots

B. Channels use unique codes to transmit simultaneously

C. All channels transmit at the same time but on different frequencies

D. Channels combine wavelengths to send data

Solution

1. Step 1: Understand Frequency Division Multiplexing (FDM)

   FDM assigns different frequency bands to each channel so they can transmit simultaneously without interference.

2. Step 2: Analyze the given frequencies and options

   The channels at 100 MHz, 110 MHz, and 120 MHz transmit at the same time but on different frequencies, unlike time division or code division multiplexing.

3. Final Answer:

   All channels transmit at the same time but on different frequencies -> Option C

4. Quick Check:

   FDM = simultaneous different frequencies [OK]

Hint: F in FDM means frequency, so different frequencies [OK]

Common Mistakes:

• Thinking FDM uses time slots
• Confusing FDM with CDM code usage
• Assuming wavelength combination applies here

4. A student wrote that in Time Division Multiplexing (TDM), all channels transmit simultaneously on different frequencies. What is the error in this statement?

medium

A. TDM combines wavelengths for transmission

B. TDM uses different codes, not frequencies

C. TDM is only used for analog signals

D. TDM transmits signals one after another in time slots, not simultaneously

Solution

1. Step 1: Review how Time Division Multiplexing works

   TDM divides time into slots and assigns each channel a slot to transmit sequentially, not simultaneously.

2. Step 2: Identify the mistake in the student's statement

   The student incorrectly said channels transmit simultaneously on different frequencies, which describes FDM, not TDM.

3. Final Answer:

   TDM transmits signals one after another in time slots, not simultaneously -> Option D

4. Quick Check:

   TDM = sequential time slots, not simultaneous [OK]

Hint: TDM means time slots, not simultaneous frequencies [OK]

Common Mistakes:

• Confusing TDM with FDM
• Assuming TDM uses codes or wavelengths
• Thinking TDM only works for analog signals

5. In a fiber optic system using Wavelength Division Multiplexing (WDM), four data streams are combined using wavelengths 850 nm, 1310 nm, 1550 nm, and 1625 nm. If one wavelength channel fails, what is the best approach to maintain communication without losing all data?

hard

A. Switch all data streams to a single wavelength immediately

B. Use redundancy by adding backup wavelengths for critical data streams

C. Convert WDM to TDM to avoid wavelength failure

D. Increase the power of the remaining wavelengths to cover the lost one

Solution

1. Step 1: Understand Wavelength Division Multiplexing (WDM) and failure impact

   WDM uses different light wavelengths to carry separate data streams. If one wavelength fails, that data stream is lost unless there is backup.

2. Step 2: Evaluate options to maintain communication

   Adding backup wavelengths (redundancy) for critical streams ensures communication continues even if one channel fails. Switching all streams to one wavelength or increasing power won't solve the failure. Converting to TDM is not practical on the fly.

3. Final Answer:

   Use redundancy by adding backup wavelengths for critical data streams -> Option B

4. Quick Check:

   WDM failure needs backup wavelengths [OK]

Hint: Backup wavelengths keep WDM data safe [OK]

Common Mistakes:

• Trying to merge all streams on one wavelength
• Thinking power increase fixes wavelength failure
• Assuming switching multiplexing types is easy