From the book : Internet of Things From Hype to Reality: The Road to Digitization (2nd ed), Ammar Rayes, Samer Salam. 2019. Springer International Publishing At the end of the chapter I (page 30-33),_ let's find Problems and Exercises, Please need your help tp answer below questions:

1. Circuit-switched networks are designed with either frequency-division multi- plexing (FDM) or time-division multiplexing (TDM). For TDM link, time is divided into frames of fixed duration, and each frame is divided onto a fixed number of time slots as shown below (for a network link supporting up to three connections/circuits).

(a) How does FDM work in circuit-switched networks?

(b) What is the typical frequency band in tradition circuit-switched-based tele- phone networks/public-switched telephone network (PSTN)?

(c) Compare FDM with TDM.

(d) Draw FDM and TDM for a tradition circuit-switched network link supporting up to five connections/circuits.

Thanks very much