Unit 6 - Practice Quiz

1 What is the primary function of the Physical Layer in the OSI model?

2 Which of the following is NOT a fundamental component of a data communication system?

3 Data flow in a system where communication can happen in both directions but not at the same time is called:

4 Which of the following is an example of a guided transmission medium?

5 Fiber optic cables transmit data in the form of:

6 Which transmission medium is commonly used for TV distribution and cable internet?

7 Unguided media is also commonly referred to as:

8 The loss of signal energy as it travels through a medium is known as:

9 Which type of transmission impairment alters the shape of the signal?

10 Random, unwanted electrical signals that interfere with the transmitted data are called:

11 Which of the following describes a Wireless Local Area Network (WLAN)?

12 IEEE 802.11 is a set of standards for which type of network?

13 Which IEEE 802.11 standard operates in the 5 GHz band with a maximum data rate of 54 Mbps?

14 Which of the following IEEE 802.11 standards introduced Multiple Input Multiple Output (MIMO) technology?

15 What is the maximum data rate of the IEEE 802.11b standard?

16 What is a network of Bluetooth devices called?

17 In a Bluetooth piconet, what is the maximum number of active slave devices that can connect to a single master?

18 Multiple interconnected piconets form a larger Bluetooth network known as a:

19 Which Bluetooth layer is roughly equivalent to the physical layer of the OSI model?

20 What frequency band does Bluetooth operate in?

21 A digital signal has 8 levels. How many bits are required to represent each level, and what is the bit rate if the baud rate is 1000 baud?

22 Which of the following line coding schemes ensures synchronization by providing a transition at the middle of every bit interval, regardless of the data bits?

23 According to the Nyquist theorem, what is the maximum bit rate for a noiseless channel with a bandwidth of 3 kHz using a signal with 4 discrete levels?

24 In optical fibers, to maintain total internal reflection, how must the refractive index of the core () compare to the refractive index of the cladding ()?

25 Which phenomenon limits the maximum transmission distance in multimode step-index optical fibers by causing pulses to spread out and overlap?

26 Why are unshielded twisted pair (UTP) cables twisted?

27 Which of the following unguided media requires strictly line-of-sight transmission and is highly susceptible to rain fade?

28 A signal travels through a cable and its power drops from 100 mW to 1 mW. What is the attenuation in decibels (dB)?

29 If the Signal-to-Noise Ratio (SNR) of a channel is 0 (i.e., signal power equals noise power), what is the Shannon capacity of a channel with a 1 MHz bandwidth?

30 Which type of transmission impairment is caused by different frequency components of a signal traveling at different propagation speeds through a guided medium?

31 A transmission channel has an of 30. Approximately what is the actual signal-to-noise power ratio (SNR)?

32 In wireless networking, what problem occurs when two stations can both transmit to a central access point, but cannot detect each other's signals?

33 Why is CSMA/CD generally not used in wireless networks?

34 Which of the following IEEE 802.11 standards operates in the 5 GHz band and uses Orthogonal Frequency Division Multiplexing (OFDM) to achieve up to 54 Mbps?

35 How does IEEE 802.11g maintain backward compatibility with IEEE 802.11b while offering higher data rates?

36 Which major physical layer enhancement was introduced in IEEE 802.11n to significantly increase throughput and range?

37 In the IEEE 802.11 MAC architecture, what is the primary function of the Distributed Coordination Function (DCF)?

38 In a Bluetooth piconet, what is the maximum number of active slave devices that can be connected to a single master device at one time?

39 In Bluetooth architecture, what is a 'scatternet'?

40 Which Bluetooth layer is responsible for multiplexing multiple logical connections, segmenting, and reassembling larger packets from upper layers?

41 A communication channel has a bandwidth of . The signal-to-noise ratio (SNR) is $63$. If a system uses multi-level signaling to achieve exactly the Shannon capacity, what is the minimum number of signal levels () required according to the Nyquist theorem?

42 A signal travels through a cascade of three devices: an amplifier with a gain of , a cable with an attenuation of spanning , and a final amplifier. If the input power is and the required output power is , what must be the gain of the final amplifier?

43 Consider a continuous periodic signal represented by a Fourier series. If the fundamental frequency is , and a low-pass filter with a cutoff frequency of is applied, what is the maximum number of harmonics (including the fundamental) that will successfully pass through the channel for a purely square wave?

44 In a step-index multi-mode optical fiber, if the core refractive index is and the cladding refractive index is , what is the fractional index change () and the approximate maximum acceptance angle () in a vacuum?

45 Which of the following scenarios maximizes the free-space path loss (FSPL) in an unguided microwave link, assuming constant antenna gains?

46 In IEEE 802.11n, spatial multiplexing is used to increase throughput. If a system uses a MIMO configuration with a channel and short guard interval, how does it achieve its theoretical maximum physical layer data rate of compared to a setup?

47 Which specific backward compatibility mechanism causes severe throughput degradation in an IEEE 802.11g network when an 802.11b client associates with the AP?

48 In the IEEE 802.11 MAC architecture, what is the exact function of the Network Allocation Vector (NAV) during an RTS/CTS exchange?

49 In a Bluetooth Scatternet, node X functions as a slave in Piconet 1 and a master in Piconet 2. Since Bluetooth devices possess a single transceiver, how does node X manage participation in both piconets?

50 Which of the following accurately describes the error correction applied to the header of a Bluetooth Baseband packet?

51 In IEEE 802.11n, Frame Aggregation is introduced to improve MAC efficiency. What is the fundamental difference in error recovery between A-MSDU and A-MPDU?

52 In a cellular network utilizing a hexagonal grid, if the cluster size is and the radius of a cell is , what is the exact co-channel reuse ratio ()?

53 A receiver operates at a temperature of with a bandwidth of . If the received signal power is and Boltzmann's constant is , what is the approximate Signal-to-Noise Ratio (SNR) in decibels?

54 In IEEE 802.11a OFDM, how are the 64 subcarriers distributed for actual transmission operations?

55 At the Bluetooth L2CAP layer, which of the following mechanisms provides a reliable channel utilizing a sliding window protocol and Go-Back-N or Selective Reject retransmission?

56 In Direct Sequence Spread Spectrum (DSSS) systems like CDMA, the near-far problem severely degrades performance. Which technique is strictly necessary at the Physical Layer to counteract this?

57 A network transmits $1500$-byte frames over a link spanning . The signal propagation speed is . What is the bandwidth-delay product of this link, and what does it represent?

58 When designing a point-to-point microwave link over unguided media, how much of the first Fresnel zone must ideally be free of obstacles to consider the path equivalent to free space, and what happens if an obstacle intrudes exactly at the boundary of the first Fresnel zone?

59 A baseband transmission system uses Manchester encoding. If the data rate is , what are the minimum and maximum fundamental frequencies generated in the physical channel depending on the data pattern?

60 In Bluetooth Basic Rate (BR), the frequency hopping spread spectrum (FHSS) operates at . If an ACL link utilizes multi-slot packets (e.g., DH5), how does the hopping mechanism behave during the transmission of this packet?