6. Explain the operation of digital modulation techniques, including amplitude shift  keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK).

7. Compare and contrast circuit switching and packet switching in network  communication.

8. Explain the operation of virtual circuits and datagram networks in packet-switched  networks. Discuss the advantages and limitations of each approach.

9. Discuss the transmission modes in data communication, particularly parallel  transmission and serial transmission.

10. Explain the concept of switching in network communication. Discuss the different  types of switches, including circuit switches, packet switches, and virtual circuit  switches.

11. Explain the operation of statistical multiplexing and wavelength division multiplexing  (WDM) in telecommunications systems.