3.1 Transmission Media (Guided vs Unguided)
Transmission Media represents the physical communication pathway between sender and receiver. Media is categorized into Guided (bounded/wired) where signals are constrained inside a physical conductor, and Unguided (wireless) where electromagnetic waves propagate freely through air or vacuum.
Figure 3.1: Categorization of guided (wired) and unguided (wireless) physical transmission media.
3.2 Multiplexing Techniques (FDM vs TDM vs WDM)
Multiplexing is the technique of combining multiple independent incoming data signals into a single aggregated stream over a shared physical communication channel, maximizing channel capacity utilization.
Figure 3.2: FDM partitions the channel by frequency bands; TDM partitions channel access by cyclic time slots.
3.3 Switching Techniques (Circuit vs Packet Switching)
In large communication networks, data must be switched across intermediate nodes to reach its destination. The two dominant switching paradigms are Circuit Switching and Packet Switching.
Figure 3.3: Circuit switching holds a dedicated end-to-end line open; Packet switching shares lines dynamically across packets.
