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Questions and Answers
What is multiplexing?
What is multiplexing?
Multiplexing is a set of techniques that allow the simultaneous transmission of multiple signals across a single data link.
Which two main types of multiplexing are discussed in the document?
Which two main types of multiplexing are discussed in the document?
FDM can be applied when the bandwidth of a link is greater than the combined bandwidths of the signals being transmitted.
FDM can be applied when the bandwidth of a link is greater than the combined bandwidths of the signals being transmitted.
True
In TDM, all signals share the same frequency but are transmitted at different time slots.
In TDM, all signals share the same frequency but are transmitted at different time slots.
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What does the term 'interleaving' refer to in TDM?
What does the term 'interleaving' refer to in TDM?
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In Synchronous TDM, the multiplexer allocates the same time slot to each device regardless of whether or not the device has data to transmit.
In Synchronous TDM, the multiplexer allocates the same time slot to each device regardless of whether or not the device has data to transmit.
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Asynchronous TDM offers flexibility, allowing the number of time slots in each frame to be adjusted based on the demand.
Asynchronous TDM offers flexibility, allowing the number of time slots in each frame to be adjusted based on the demand.
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What is WDM?
What is WDM?
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In the context of wireless communication, how does SDM work?
In the context of wireless communication, how does SDM work?
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What is the primary purpose of multiple access methods in telecommunications and computer networks?
What is the primary purpose of multiple access methods in telecommunications and computer networks?
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Which of the following is NOT an example of shared physical media?
Which of the following is NOT an example of shared physical media?
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TDMA is a special form of TDM used in the digital 2G cellular systems such as GSM.
TDMA is a special form of TDM used in the digital 2G cellular systems such as GSM.
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FDMA allocates different frequency bands to different data streams, making it ideal for applications like satellite communication and cellular phone systems.
FDMA allocates different frequency bands to different data streams, making it ideal for applications like satellite communication and cellular phone systems.
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What is the principle behind CDMA?
What is the principle behind CDMA?
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CDMA finds application in:
CDMA finds application in:
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Study Notes
Digital Communication and Switching - Lecture Notes
- Course: Digital Communication and Switching
- Semester: I AY 2024-25
- Lecture: 8 & 9 - Multiplexing
- Lecturer: Lenin Joseph (LJ)
- Date: Dec 25, 2024
Multiplexing
- Multiplexing is a set of techniques enabling simultaneous transmission of multiple signals across a single data link.
- Key techniques include Frequency-Division Multiplexing (FDM) and Time-Division Multiplexing (TDM).
- FDM divides the available bandwidth into non-overlapping frequency sub-bands, each carrying a separate signal.
- TDM transmits multiple signals over a single channel by allocating them, in turn, different time slots.
Frequency-Division Multiplexing (FDM)
- Divides the total bandwidth into non-overlapping frequency sub-bands.
- Each sub-band carries a separate signal.
- Suitable when link bandwidth exceeds combined bandwidth of signals.
- Applications include: Telemetry, FM and TV broadcasting, telephone calls via high-capacity trunk lines, satellite communication, and broadband DSL.
Time-Division Multiplexing (TDM)
- Transmits multiple signals over a single channel by assigning alternating time slots.
- Ideal when transmission medium data rate surpasses sender/receiver data requirements.
- Includes synchronous and asynchronous types.
- Applications include: Telegraphy, Digital Telephony
Synchronous TDM
- Allocates the same time slot to each device irrespective of data transmission needs.
- No addressing required.
- Inefficient: link capacity not fully utilized if not all devices have data to send.
- Data transmission in a fixed order.
Asynchronous TDM
- Flexible approach – time slots allocated only when data is present.
- Time slot allocation not fixed.
- Requires addressing to identify source of data in a frame.
- More efficient than synchronous TDM, maximizing link usage.
Wave-Division Multiplexing (WDM)
- Similar to FDM, but for light signals transmitted through fiber optic channels.
- Employs very high frequencies.
Space Division Multiplexing (SDM)
- Transmits multiple wireless signals simultaneously on a common frequency without interference.
- Achieved via multiple antenna elements forming a phased array antenna.
Multiple Access Techniques
- Channel access methods permitting multiple terminals to share a multi-point transmission medium.
- Examples include wireless networks, bus networks, ring networks, and star networks.
- Based on multiplexing methods (allowing several data streams/signals to share one channel).
Time Division Multiple Access (TDMA)
- Special form of TDM enabling sharing of a single frequency channel through allocating time slots.
- Employed in digital 2G cellular systems like GSM.
- Time slots allocated one-by-one.
Frequency Division Multiple Access (FDMA)
- Channel access scheme based on FDM for different data streams.
- Data streams allocated to specific frequency bands.
- Example – early (1G) cell phone systems, where calls were assigned to different uplink/downlink channels.
Space Division Multiple Access (SDMA)
- Channel access method for mobile communication systems to reuse cell phone frequencies in a service area.
- Reusing frequencies possible with adequate separation between cells.
Code Division Multiple Access (CDMA)
- Multiple access scheme based on spread spectrum.
- Utilizes wider radio spectrum than data rate.
- Allows multiple simultaneous signals over same carrier frequency using unique spreading codes.
- Employed in satellite systems (sharing transponders) and cellular phone systems for efficient use of spectrum compared to other methods.
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Description
Explore the fundamentals of multiplexing in Digital Communication and Switching with a focus on Frequency-Division Multiplexing (FDM) and Time-Division Multiplexing (TDM). This quiz covers essential concepts related to how multiple signals can be transmitted simultaneously over a single data link. Enhance your understanding of these crucial techniques used in various applications.
