Physical Layer

Physical communication layer is the building block for all other layers. It provides point-to-point connection to transport bit streams. The central issue here is how to send binary information from one location to another using a particular physical channel which is often analog in nature. Specifically, we are faced with the following questions:

• Physical characteristics of the channel
• Modulating schemes used to carry digital information over analog channels
• Analog vs. digital channels
• Bit error rate performance associated with the particular modulating scheme
• maximum channel rates (channel capacities)
• Transmission and Switching
  • Time Division Multiplexing
  • Time Division Switching
  • TDM Hierarchy
  • Channel Bandwidth Allocations Using TDM
  • Integrated Digital Services Networks (ISDN)