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Data Communications and Networking 5th edition Behrouz A. Forouzan - Solutions
What is the transmission time of a packet sent by a station if the length of the packet is 1 million bytes and the bandwidth of the channel is 200 Kbps?
What is the length of a bit in a channel with a propagation speed of 2 × 108 m/s if the channel bandwidth isa. 1 Mbps?b. 10 Mbps?c. 100 Mbps?
How many bits can fit on a link with a 2 ms delay if the bandwidth of the link isa. 1 Mbps?b. 10 Mbps?c. 100 Mbps?
What is the total delay (latency) for a frame of size 5 million bits that is being sent on a link with 10 routers each having a queuing time of 2 μs and a processing time of 1 μs. The length of the link is 2000 Km. The speed of light inside the link is 2 × 108 m/s. The link has a bandwidth of 5
Calculate the value of the signal rate for each case in Figure 4.2 if the data rate is 1 Mbps and c = 1/2.Figure 4.2a. One data element per one signal element (r = 1)b. One data element per two signal elements r = (1/2)c. Two data elements per one signal element (r = 2)d. Four data
Distinguish between a signal element and a data element.
In a digital transmission, the sender clock is 0.2 percent faster than the receiver clock. How many extra bits per second does the sender send if the data rate is 1 Mbps?
Distinguish between data rate and signal rate.
Draw the graph of the NRZ-L scheme using each of the following data streams, assuming that the last signal level has been positive. From the graphs, guess the bandwidth for this scheme using the average number of changes in the signal level. Compare your guess with the corresponding entry inTable
Define baseline wandering and its effect on digital transmission.
Define a DC component and its effect on digital transmission.
Define the characteristics of a self-synchronizing signal.
Repeat Problem P4-3 for the 2B1Q scheme, but use the following data streams.a. 0000000000000000b. 1111111111111111c. 0101010101010101d. 0011001100110011Problem 4-3Draw the graph of the NRZ-L scheme using each of the following data streams, assuming that the last signal level has been positive. From
Repeat Problem P4-3 for the MLT-3 scheme, but use the following data streams.a. 00000000b. 11111111c. 01010101d. 00011000Problem 4-3Draw the graph of the NRZ-L scheme using each of the following data streams, assuming that the last signal level has been positive. From the graphs, guess the
Find the 8-bit data stream for each case depicted in Figure 4.36. Time a. NRZ-I Time b. differential Manchester
An NRZ-I signal has a data rate of 100 Kbps. Using Figure 4.6, calculate the value of the normalized energy (P) for frequencies at 0 Hz, 50 KHz, and 100 KHz.Figure 4.6 10 | 0 | 1 0 | r = 1 Save = N/2 NRZ-L Time P Bandwidth NRZ-I Time 0.5 2 fIN 1 O No inversion: Next bit is 0 Inversion: Next bit is 1
A Manchester signal has a data rate of 100 Kbps. Using Figure 4.8, calculate the value of the normalized energy (P) for frequencies at 0 Hz, 50 KHz, 100 KHz.Figure 4.8 O is L 1 is 1 Save = N ave 2 Manchester Time 1- Bandwidth 0.5– 0+ Differential 2 f/N Manchester Time
The input stream to a 4B/5B block encoder is0100 0000 0000 0000 0000 0001Answer the following questions:a. What is the output stream?b. What is the length of the longest consecutive sequence of 0s in the input?c. What is the length of the longest consecutive sequence of 0s in the output?
What is the result of scrambling the sequence 11100000000000 using each of the following scrambling techniques? Assume that the last non-zero signal level has been positive.a. B8ZSb. HDB3 (The number of nonzero pulses is odd after the last substitution.)
What is the Nyquist sampling rate for each of the following signals?a. A low-pass signal with bandwidth of 200 KHz?b. A band-pass signal with bandwidth of 200 KHz if the lowest frequency is 100 KHz?
What is the maximum data rate of a channel with a bandwidth of 200 KHz if we use four levels of digital signaling.
We have a baseband channel with a 1-MHz bandwidth. What is the data rate for this channel if we use each of the following line coding schemes?a. NRZ-Lb. Manchesterc. MLT-3d. 2B1Q
Which of the four digital-to-analog conversion techniques (ASK, FSK, PSK or QAM) is the most susceptible to noise? Defend your answer.
What is the position of the transmission media in the OSI or the Internet model?
If the power at the beginning of a 1 Km 2.6/9.5 mm coaxial cable is 200 mw, what is the power at the end for frequencies 1 KHz, 10 KHz, and 100 KHz? Use the results of Problem P7-4.
A light signal is travelling through a fiber. What is the delay in the signal if the length of the fiber-optic cable is 10 m, 100 m, and 1 Km (assume a propagation speed of 2 × 108 m)?
Consider an n × k crossbar switch with n inputs and k outputs.a. Can we say that the switch acts as a multiplexer if n > k?b. Can we say that the switch acts as a demultiplexer if n < k?
We need a three-stage space-division switch with N = 100. We use 10 crossbars at the first and third stages and 4 crossbars at the middle stage.a. Draw the configuration diagram.b. Calculate the total number of crosspoints.c. Find the possible number of simultaneous connections.d. Find the possible
We want to transmit 1000 characters with each character encoded as 8 bits.a. Find the number of transmitted bits for synchronous transmission.b. Find the number of transmitted bits for asynchronous transmission.c. Find the redundancy percent in each case.
Define analog transmission.
Calculate the baud rate for the given bit rate and type of modulation.a. 2000 bps, FSKb. 4000 bps, ASKc. 6000 bps, QPSKd. 36,000 bps, 64-QAM
Define carrier signal and explain its role in analog transmission.
Calculate the bit rate for the given baud rate and type of modulation.a. 1000 baud, FSKb. 1000 baud, ASKc. 1000 baud, BPSKd. 1000 baud, 16-QAM
Define digital-to-analog conversion.
What is the number of bits per baud for the following techniques?a. ASK with four different amplitudesb. FSK with eight different frequenciesc. PSK with four different phasesd. QAM with a constellation of 128 points
Which characteristics of an analog signal are changed to represent the digital signal in each of the following digital-to-analog conversions?a. ASKb. FSKc. PSKd. QAM
Draw the constellation diagram for the following:a. ASK, with peak amplitude values of 1 and 3b. BPSK, with a peak amplitude value of 2c. QPSK, with a peak amplitude value of 3d. 8-QAM with two different peak amplitude values, 1 and 3, and four different phases
Draw the constellation diagram for the following cases. Find the peak amplitude value for each case and define the type of modulation (ASK, FSK, PSK, or QAM).The numbers in parentheses define the values of I and Q respectively.a. Two points at (2, 0) and (3, 0)b. Two points at (3, 0) and (−3,
Define constellation diagram and explain its role in analog transmission.
How many bits per baud can we send in each of the following cases if the signal constellation has one of the following number of points?a. 2b. 4c. 16d. 1024
What are the two components of a signal when the signal is represented on a constellation diagram? Which component is shown on the horizontal axis? Which is shown on the vertical axis?
What is the required bandwidth for the following cases if we need to send 4000 bps? Let d = 1.a. ASKb. FSK with 2Δf = 4 KHzc. QPSKd. 16-QAM
Define analog-to-analog conversion.
The telephone line has 4 KHz bandwidth. What is the maximum number of bits we can send using each of the following techniques? Let d = 0.a. ASKb. QPSKc. 16-QAMd. 64-QAM
Which characteristics of an analog signal are changed to represent the lowpass analog signal in each of the following analog-to-analog conversions?a. AMb. FMc. PM
A corporation has a medium with a 1-MHz bandwidth (lowpass). The corporation needs to create 10 separate independent channels each capable of sending at least 10 Mbps. The company has decided to use QAM technology. What is the minimum number of bits per baud for each channel? What is the number of
Which of the three analog-to-analog conversion techniques (AM, FM, or PM) is the most susceptible to noise? Defend your answer.
A cable company uses one of the cable TV channels (with a bandwidth of 6 MHz) to provide digital communication for each resident. What is the available data rate for each resident if the company uses a 64-QAM technique?
Find the bandwidth for the following situations if we need to modulate a 5-KHz voice.a. AMb. FM (β = 5)c. PM (β = 1)
Find the total number of channels in the corresponding band allocated byFCC.a. AMb. FM
Describe the goals of multiplexing.
Assume that a voice channel occupies a bandwidth of 4 kHz. We need to multiplex 10 voice channels with guard bands of 500 Hz using FDM. Calculate the required bandwidth.
List three main multiplexing techniques mentioned in this chapter.
We need to transmit 100 digitized voice channels using a passband channel of 20 KHz. What should be the ratio of bits/Hz if we use no guard band?
Which of the three multiplexing techniques is (are) used to combine analog signals? Which of the three multiplexing techniques is (are) used to combine digital signals?
In the analog hierarchy of Figure 6.9, find the overhead (extra bandwidth for guard band or control) in each hierarchy level (group, supergroup, master group, and jumbo group).Figure 6.9 48 kHz 12 voice channels 4 kHz 240 kHz 60 voice channels 4 kHz 5 Group D 2.52 MHz 600 voice channels M F 10
We need to use synchronous TDM and combine 20 digital sources, each of 100 Kbps. Each output slot carries 1 bit from each digital source, but one extra bit is added to each frame for synchronization. Answer the following questions:a. What is the size of an output frame in bits?b. What is the output
Define the analog hierarchy used by telephone companies and list different levels of the hierarchy.
Define the digital hierarchy used by telephone companies and list different levels of the hierarchy.
We have 14 sources, each creating 500 8-bit characters per second. Since only some of these sources are active at any moment, we use statistical TDM to combine these sources using character interleaving. Each frame carries 6 slots at a time, but we need to add 4-bit addresses to each slot. Answer
Which of the three multiplexing techniques is common for fiber-optic links? Explain the reason.
Ten sources, six with a bit rate of 200 kbps and four with a bit rate of 400 kbps, are to be combined using multilevel TDM with no synchronizing bits. Answer the following questions about the final stage of the multiplexing:a. What is the size of a frame in bits?b. What is the frame rate?c. What is
Distinguish between multilevel TDM, multiple-slot TDM, and pulse-stuffed TDM.
Four channels, two with a bit rate of 200 kbps and two with a bit rate of 150 kbps, are to be multiplexed using multiple-slot TDM with no synchronization bits. Answer the following questions:a. What is the size of a frame in bits?b. What is the frame rate?c. What is the duration of a frame?d. What
Distinguish between synchronous and statistical TDM.
Two channels, one with a bit rate of 190 kbps and another with a bit rate of 180 kbps, are to be multiplexed using pulse-stuffing TDM with no synchronization bits. Answer the following questions:a. What is the size of a frame in bits?b. What is the frame rate?c. What is the duration of a frame?d.
Define spread spectrum and its goal. List the two spread spectrum techniques discussed in this chapter.
Answer the following questions about a T-1 line:a. What is the duration of a frame?b. What is the overhead (number of extra bits per second)?
Define FHSS and explain how it achieves bandwidth spreading.
Define DSSS and explain how it achieves bandwidth spreading.
Figure 6.34 shows a multiplexer in a synchronous TDM system. Each output slot is only 10 bits long (3 bits taken from each input plus 1 framing bit). What is the output stream? The bits arrive at the multiplexer as shown by the arrows.Figure 6.34 1011101111 0 1 – Frame of 10 bits 111111100 0 0
Figure 6.35 shows a demultiplexer in a synchronous TDM. If the input slot is 16 bits long (no framing bits), what is the bit stream in each output? The bits arrive at the demultiplexer as shown by the arrows.Figure 6.35 10100000||10 1 0101010100001||0111000001111000 TDM
Answer the following questions about the digital hierarchy inFigure 6.23:a. What is the overhead (number of extra bits) in the DS-1 service?b. What is the overhead (number of extra bits) in the DS-2 service?c. What is the overhead (number of extra bits) in the DS-3 service?d. What is the overhead
What is the minimum number of bits in a PN sequence if we use FHSS with a channel bandwidth of B = 4 KHz and Bss = 100 KHz?
An FHSS system uses a 4-bit PN sequence. If the bit rate of the PN is 64 bits per second, answer the following questions:a. What is the total number of possible channels?b. What is the time needed to finish a complete cycle of PN?
A pseudorandom number generator uses the following formula to create a random series:Ni + 1 = (5 + 7Ni) mod 17 - 1In which Ni defines the current random number and Ni+1 defines the next random number. The term mod means the value of the remainder when dividing (5 + 7Ni) by 17. Show the sequence
We have a digital medium with a data rate of 10 Mbps. How many 64-kbps voice channels can be carried by this medium if we use DSSS with the Barker sequence?
Using Figure 7.6, tabulate the attenuation (in dB) of a 18-gauge UTP for the indicated frequencies and distances.Figure 7.6 26 gauge Gauge Diameter (inches) 0.0403 20 24 gauge 18 18 0.02320 22 0.02010 24 16 26 0.0159 22 gauge 14 12 18 gauge 10 6. 4 10 100 1000 f (kHz) Attenuation (dB/km) Table 7.5
Name the two major categories of transmission media.
How do guided media differ from unguided media?
If the power at the beginning of a 1 Km 18-gauge UTP is 200 mw, what is the power at the end for frequencies 1 KHz, 10 KHz, and 100 KHz? Use the results of Problem P7-1.
What are the three major classes of guided media?
Using Figure 7.9, tabulate the attenuation (in dB) of a 2.6/9.5 mm coaxial cable for the indicated frequencies and distances. Table 7.6 Attenuation for 2.6/9.5 mm coaxial cable dB at 1 KHz dB at 100 KHz Distance dB at 10 KHz 1 Km 10 Km 15 Km 20 Km
What is the function of the twisting in twisted-pair cable?
What is refraction? What is reflection?
What is the purpose of cladding in an optical fiber?
Calculate the bandwidth of the light for the following wavelength ranges (assume a propagation speed of 2 × 108 m):a. 1000 to 1200 nmb. 1000 to 1400 nm
Name the advantages of optical fiber over twisted-pair and coaxial cable.
How does sky propagation differ from line-of-sight propagation?
Using Figure 7.16, tabulate the attenuation (in dB) of an optical fiber for the indicated wavelength and distances.Figure 7.16 100 50 10 0.5 0.1 0.05 0.01 800 1000 1200 1400 1600 1800 Wavelength (nm) Loss (dB/km) Table 7.7 Attenuation for optical fiber Distance 1 Km 10 Km dB at 800 nm dB at 1000
What is the difference between omnidirectional waves and unidirectional waves?
A beam of light moves from one medium to another medium with less density. The critical angle is 60°. Do we have refraction or reflection for each of the following incident angles? Show the bending of the light ray in each case.a. 40°b. 60°c. 80°
Describe the need for switching and define a switch.
A path in a digital circuit-switched network has a data rate of 1 Mbps. The exchange of 1000 bits is required for the setup and teardown phases. The distance between two parties is 5000 km. Answer the following questions if the propagation speed is 2 × 108 m:a. What is the total delay if 1000 bits
Transmission of information in any network involves end-to-end addressing and sometimes local addressing (such as VCI). Table 8.2 shows the types of networks and the addressing mechanism used in each of them.Table 8.2Answer the following questions:a. Why does a circuit-switched network need
List the three traditional switching methods. Which are the most common today?
What are the two approaches to packet switching?
Compare and contrast a circuit-switched network and a packet-switched network.
What is the role of the address field in a packet traveling through a datagram network?
What is the role of the address field in a packet traveling through a virtualcircuit network?
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