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Questions and Answers
What is the primary goal of multiplexing in bandwidth utilization?
What is the primary goal of multiplexing in bandwidth utilization?
Which statement correctly describes the role of a multiplexer (MUX) in a multiplexed system?
Which statement correctly describes the role of a multiplexer (MUX) in a multiplexed system?
What is a key feature of circuit-switched networks during the setup phase?
What is a key feature of circuit-switched networks during the setup phase?
What happens during the teardown phase of circuit-switched communication?
What happens during the teardown phase of circuit-switched communication?
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Which of the following statements best describes the data transfer process in a circuit-switched network?
Which of the following statements best describes the data transfer process in a circuit-switched network?
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In terms of resource allocation efficiency, what advantage does multiplexing provide?
In terms of resource allocation efficiency, what advantage does multiplexing provide?
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How does the teardown phase in circuit-switched networks affect overall efficiency?
How does the teardown phase in circuit-switched networks affect overall efficiency?
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What is a significant drawback of circuit-switching in resource allocation?
What is a significant drawback of circuit-switching in resource allocation?
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What is the primary advantage of statistical time-division multiplexing over synchronous TDM?
What is the primary advantage of statistical time-division multiplexing over synchronous TDM?
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Which of the following strategies can be used to manage data rates when they are not the same?
Which of the following strategies can be used to manage data rates when they are not the same?
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In statistical TDM, how does the multiplexer determine which input lines to allocate slots?
In statistical TDM, how does the multiplexer determine which input lines to allocate slots?
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What distinguishes the structure of slots in synchronous TDM from that in statistical TDM?
What distinguishes the structure of slots in synchronous TDM from that in statistical TDM?
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What is a key characteristic of spread spectrum techniques in wireless communication?
What is a key characteristic of spread spectrum techniques in wireless communication?
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Why is addressing necessary in statistical TDM but not in synchronous TDM?
Why is addressing necessary in statistical TDM but not in synchronous TDM?
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What is the role of pulse stuffing in managing data rates?
What is the role of pulse stuffing in managing data rates?
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In spread spectrum communication, what is meant by expanding bandwidth to $B_{ss}$ such that $B_{ss} ext{ » } B$?
In spread spectrum communication, what is meant by expanding bandwidth to $B_{ss}$ such that $B_{ss} ext{ » } B$?
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What are the three phases involved in circuit switching?
What are the three phases involved in circuit switching?
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During the setup phase of circuit switching, what is primarily established?
During the setup phase of circuit switching, what is primarily established?
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Why is the teardown phase significant in circuit-switched networks?
Why is the teardown phase significant in circuit-switched networks?
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What happens during the data transfer phase of circuit switching?
What happens during the data transfer phase of circuit switching?
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What is one drawback of circuit-switched networks regarding resource allocation?
What is one drawback of circuit-switched networks regarding resource allocation?
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How does the efficiency of circuit-switched networks compare to other types of networks?
How does the efficiency of circuit-switched networks compare to other types of networks?
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What is typically required for creating a connection between two end systems in circuit switched networks?
What is typically required for creating a connection between two end systems in circuit switched networks?
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What characteristic of circuit-switched networks allows for minimal delay during communication?
What characteristic of circuit-switched networks allows for minimal delay during communication?
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Study Notes
Bandwidth Utilization
- Multiplexing combines multiple low-bandwidth channels into one larger channel, improving efficiency.
- Spreading expands a channel's bandwidth to enhance privacy and anti-jamming.
- Bandwidth utilization is the use of available bandwidth for specific goals, such as efficiency or privacy.
Multiplexing
- Multiplexing allows simultaneous transmission of multiple signals across a single link when the link's bandwidth exceeds the individual devices' needs.
- The need for multiplexing arises due to increasing data and telecommunication traffic.
- A multiplexed system (n lines sharing one link) uses a multiplexer (MUX) to combine signals and a demultiplexer (DEMUX) to separate them at the receiving end.
- Efficiency, by maximizing resource utilization, especially bandwidth, is a goal of multiplexing.
Multiplexing Techniques
- Frequency-Division Multiplexing (FDM): Analog technique combining signals by modulating different carrier frequencies. Signals are separated through guard bands and carrier frequencies must not interfere with original data frequencies.
- Wavelength-Division Multiplexing (WDM): Analog technique similar to FDM, but uses wavelengths instead of frequencies to carry different signals.
- Time-Division Multiplexing (TDM): Digital technique where signals are transmitted in time slots. Each connection uses a portion of link time sequentially.
Synchronous TDM
- Input is divided into frames with each input connection occupying one time slot in each frame.
- Output duration is n times shorter than input duration (n=number of connections).
- Each time slot duration is 1/n of frame duration.
- Data rate of output link is n times faster than individual input connection's data rate.
- Efficiency can be improved by interleaving.
- If no data is available, time slots are wasted.
Statistical TDM
- Time slots are dynamically allocated based on when data is available instead of pre-assigned.
- Improved efficiency if some connections don't have data to send.
- Time slots are not always full.
- 3 management strategies can be used for unbalanced data rates (multilevel, multiple slots, and pulse stuffing).
Pulse Stuffing
- Used when bit rates of sources are not multiples of each other.
- Dummy bits are added to input lines with lower rates to equalize the overall data rate. This enables multiplexing..
Spread Spectrum
- A form of wireless communications that varies the frequency of transmitted signals.
- Increases robustness to interference and jamming.
- Spreads out the signal to occupy a wider frequency spectrum (Bss).
- Two spread spectrum implementations: FHSS and DSSS.
- Bandwidth needed is wider than the original signal needs (B).
FHSS (Frequency Hopping Spread Spectrum)
- M different carrier frequencies are used for transmitting the signal, hopping between them.
- Pseudorandom sequence determines frequency-hopping pattern.
DSSS (Direct Sequence Spread Spectrum)
- Data bit is replaced by a longer chip sequence using a spreading code.
- Chip sequence divides data in a higher rate in bandwidth.
Switching Techniques
- Circuit Switching: Establishes a dedicated connection between communicating devices for the duration of their communication, akin to establishing a telephone circuit.
- Message Switching: Each switch stores the entire message, examines it for errors or routing data, and forwards it to the next switch in the route. The message path is dynamic during transmission, not fixed.
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Packet Switching: Breaks messages into packets for transmission. Each packet is treated as an independent unit with routing information. Two types of packetswitching: Datagram and Virtual Circuit.
- Datagram Networks: Each packet is routed independently of other packets in a message.
- Virtual Circuit Networks: A dedicated path is established before transmission. Packets following this path are given a virtual circuit ID.
Addressing in Various Networks
- Circuit Switching: No need for addressing during transmission since only a dedicated channel exists.
- Message Switching: A message needs a destination address.
- Packet Switching: Each packet needs its destination address in the header, and switches use the destination address for routing.
Transmission Media (Guided)
-
Twisted-Pair Cable: Two insulated copper wires twisted together.
- UTP (Unshielded): Cheaper, less shielded.
- STP (Shielded): More expensive, shielded against noise/interference.
- Coaxial Cable: Central conductor surrounded by an insulator, an outer conductor, and a plastic sheath.
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Fiber-Optic Cable: Thin glass or plastic fibers transmit data as light.
- Multimode: Multiple light beams with varying paths.
- Single-mode: Single light beam with relatively similar paths.
Transmission Media (Unguided)
- Wireless communication methods (radio waves, microwaves, infrared).
- Radio Waves: Omnidirectional, can penetrate walls.
- Microwaves: Unidirectional, need line-of-sight.
- Infrared: Short-range, cannot penetrate walls.
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Description
This quiz covers the concepts of bandwidth utilization and multiplexing, including how multiple low-bandwidth channels can be combined into a larger channel. You'll learn about the different techniques such as Frequency-Division Multiplexing (FDM) and the role of multiplexers and demultiplexers. Test your understanding of these fundamental telecommunication principles.
