1. | Human voice frequency ranges from 16 Hz to about 20 KHz. Telephone companies use the most-significant 4,000 KHz portion of this spectrum to deliver voice conversation between two users. This downgrade in the quality of conversation allows the transmission links to save bandwidth remarkably. Using a three-level hierarchy of multiplexing (12:1, 5:1, and 10:1):
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2. | Consider the integration of three analog sources and four identical digital sources through a time-division multiplexer that uses its entire 170 Kb/s maximum capacity. The analog lineswith bandwidths of 5 KHz, 2 KHz, and 1 KHz, respectivelyare sampled, multiplexed, quantized, and 5-bit encoded. The digital lines are multiplexed, and each carries 8 Kb/s.
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3. | Assume that two 600 b/s terminals, five 300 b/s terminals, and a number of 150 b/s terminals are to be time-multiplexed in a character-interleaved format over a 4,800-b/s digital line. The terminals send 10 bits/character, and one synchronization character is inserted for every 99 data characters . All the terminals are asynchronous, and 3 percent of the line capacity is allocated for pulse stuffing to accommodate variations in the terminal clock rate.
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4. | Consider a time-division multiplexer having a frame time of 26 µ s. Each user channel has 6 bits, and each frame has 10 bits of overhead information. Assume that the transmission line carries 2 Mb/s of information.
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5. | Consider a synchronous TDM with eight inputs, each becoming an average of 2 µ s active and 6 µ s inactive. Frames can receive four channels only.
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6. | For a four-input statistical TDM, consider two different frame sizes of 2 and 3. Sketch one set of three plots, each showing the clipping probability versus = 0.2, 0.4, 0.6, 0.8. |
7. | Consider a statistical TDM in which 11 sources and 10 channels are present. Find the clipping probability, assuming a probability of 0.9 that a given source is busy. |
8. | Find the average clipping time for each burst of information in statistical TDMs. |
9. | A string of 110011101 arrives at the line coder of a modem. Give the output form if the line coder is designed by:
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10. | A string of 100101011 arrives at the modulation unit of a modem. Give the output signal if the modulator is designed by:
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11. | We want to design the input port processor of a high-speed router and analyze the delay. Incoming packets to IPP are fragmented into smaller segments, with each segment consisting of d bits data plus 50 bits of header. The switch fabric requires segments to be transmitted at r b/s. To achieve the highest possible speed:
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12. | Computer simulation project. To simulate the routing table of routers, write a computer program to construct a look-up routing table with ten entries. Each entry must contain a sequence number, time, destination address, cost of a destination node (given a certain network), and router port number. Your program should demonstrate the updating mechanism on a frequent basis. |