Exercícios - Parte 1 - Perguntas PDF

Chapter 7 (Kurose) Review Questions SECTION 7.2 R3. What are the differences between the following types of wireless channel impairments: path loss, multipath propagation, interference from other sources? R4. As a mobile node gets farther and farther away from a base station, what are two actions t...

Chapter 7 (Kurose) Review Questions SECTION 7.2 R3. What are the differences between the following types of wireless channel impairments: path loss, multipath propagation, interference from other sources? R4. As a mobile node gets farther and farther away from a base station, what are two actions that a base station could take to ensure that the loss probability of a transmitted frame does not increase? Problems P1. Consider the single-sender CDMA example in Figure 7.5. What would be the sender’s output (for the 2 data bits shown) if the sender’s CDMA code were (1, -1, 1, -1, 1, 1, 1, -1)? P2. Consider sender 2 in Figure 7.6. What is the sender’s output to the channel (before it is added to the signal from sender 1), Z2 i,m? P3. Suppose that the receiver in Figure 7.6 wanted to receive the data being sent by sender 2. Show (by calculation) that the receiver is indeed able to recover sender 2’s data from the aggregate channel signal by using sender 2’s code. P4. For the two-sender, two-receiver example, give an example of two CDMA codes containing 1 and 21 values that do not allow the two receivers to extract the original transmitted bits from the two CDMA senders. Comer (6th Edition) EXERCISES 8.7 Define the concept of Hamming distance. 8.8 Compute the Hamming distance for the following pairs: ( 0000, 0001 ), ( 0101, 0001 ), ( 1111, 1001 ), and ( 0001, 1110 ). Forouzan (4th edition) Q5-2. Define carrier signal and explain its role in analog transmission. Q5-4. Which characteristics of an analog signal are changed to represent the digital signal in each of the following digital-to-analog conversions? Q5-5. Which of the four digital-to-analog conversion techniques (ASK, FSK, PSK or QAM) is the most susceptible to noise? Defend your answer. Q5-6. Define constellation diagram and explain its role in analog transmission. Q6-1. Describe the goals of multiplexing. Capítulo 14 3. Em que difere o OFDM do FDM? Tanenbaum (6th edition) Capítulo 2 18. A modem constellation diagram similar to Fig. 2-17 has data points at (0, 1) and (0, 2). Does the modem use phase modulation or amplitude modulation? 21. Suppose that A, B, and C are simultaneously transmitting 0 bits, using a CDMA system with the chip sequences of Fig. 2-22(a). What is the resulting chip sequence? A = (–1 –1 –1 +1 +1 –1 +1 +1); B = (–1 –1 +1 –1 +1 +1 +1 –1); C = (–1 +1 –1 +1 +1 +1 –1 –1); D = (–1 +1 –1 –1 –1 –1 +1 –1) 23. Consider a different way of looking at the orthogonality property of CDMA chip sequences. Each bit in a pair of sequences can match or not match. Express the orthogonality property in terms of matches and mismatches. 24. A CDMA receiver gets the following chips: (-1 +1 -3 +1 -1 -3 +1 +1). Assuming the chip sequences defined in Fig. 2-22(a), which stations transmitted, and which bits did each one send? 25. In Fig. 2-22, there are four stations that can transmit. Suppose four more stations are added. Provide the chip sequences of these stations. Stallings - Wireless (2016 edition) 5.15 Briefly define OFDM, OFDMA. 5.17 List three benefits of spread spectrum. 5.18 What is frequency hopping spread spectrum? 5.19 What is direct sequence spread spectrum? 5.20 What is CDMA? Hassan – Wireless (2022) Chapter 2 Multiple Choice, True/False, and Fill-in-Blanks Questions Q2. 10 W is equivalent to — dBm. Q4. It is impossible to send 3000 bits/second through a wire which has a bandwidth of 1000 Hz. Q11. 64-QAM has 16 bits per symbol. Review Exercises Q1. What is the wavelength of a signal operating at the frequency of 2.4 GHz? Q2. What is the frequency of a signal having a wavelength of 50 cm? Q3. Represent the following powers in dBm: A. 100 kW Q5. How many Watts of power is: A. 30 dBm Q6. Received signal strength is measured at 10 mW. What is the noise power in dBm, if SNR = 10 dB? Q7. A telephone line is known to have a loss of 20 dB. The input signal power is measured at 1 Watt, and the output signal noise level is measured at 1 mW. Using this information, calculate the output signal to noise ratio (SNR) in dB. Q8. What is the maximum data rate that can be supported on a 10 MHz noise-less channel if the channel uses eight-level digital signals? Chapter 3 True/False and MCQ Q1. With a subcarrier spacing of 10 kHz, how many subcarriers will be used in an OFDM system with 8 MHz channel bandwidth? Q2. Let us consider an OFDM system that uses the same carrier spacing irrespective of the channel bandwidth used. It employs 1024 subcarriers for 10 MHz channel. How many subcarriers will be used if the channel was 1.25 MHz wide?