Lec-4: Physical layer in computer networks in hindi | Functions of Physical layer | OSI
Understanding the Physical Layer in OSI Model
Overview of the Physical Layer
- The physical layer is the first layer from the bottom of the OSI model and serves as the last layer on the sender's side, while being the first on the receiver's side.
- It provides functionalities to higher layers, specifically delivering bits received from data link layer for transmission.
Functions of the Physical Layer
- The physical layer decides how to send signals using transmission media, which can be guided (wired) or unguided (wireless).
- It deals with hardware components such as cables and connectors, converting logical data into actual signals for transmission.
Types of Cables and Connectors
- Various types of cables are used in physical layer communications: twisted pair cables, coaxial cables, and optical fibers. Each has unique functionalities.
- Connectors like UTP, BNC, and MGRT are essential hardware devices that facilitate connections between different types of cables.
Topology in Physical Layer
- Physical topology refers to how devices are connected; common topologies include star, mesh, and bus configurations.
- Point-to-point communication is a specific configuration where only one sender communicates with one receiver without sharing lines with others.
Hardware Components in Physical Layer
- Key hardware components include repeaters (to boost signal strength due to attenuation caused by noise) and hubs (for multipoint connections).
- Detailed explanations about these components can be found in previous videos linked in the description box.
Transmission Modes
- The physical layer discusses various transmission modes: simplex (one-way communication), half-duplex (two-way but not simultaneous), and full duplex (simultaneous two-way communication).
Understanding Multiplexing and Encoding in Communication
Multiplexing Concepts
- Signals can be sent through various frequencies, allowing multiple small channels within a single channel. This method eliminates the need to purchase new channels for each signal.
- Multiplexing combines multiple signals into one for transmission, while demultiplexing separates that single signal back into its original multiple signals at the receiver's end.
- The primary advantage of multiplexing is efficient use of the same channel for different types of data transmission.
Encoding Techniques
- Different encoding methods are utilized based on the type of data being transmitted. Digital devices generate discrete data that must be encoded appropriately before transmission.