JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA 2022 COMPUTER NETWORKS Previous Question Paper (October/November - 2022 - R20)

The OSI (Open Systems Interconnection) reference model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven distinct layers to ensure interoperability between diverse communication systems.

1. Physical Layer: Transmits raw bit streams over a physical medium. It defines hardware specifications, voltage levels, and cable types.
2. Data Link Layer: Provides node-to-node data transfer and handles error detection and correction from the physical layer. It manages framing and physical addressing (MAC).
3. Network Layer: Manages logical addressing and routing of packets across different networks. It determines the best path for data transmission.
4. Transport Layer: Ensures end-to-end communication, flow control, and error recovery. It segments data and manages transmission reliability (e.g., TCP/UDP).
5. Session Layer: Establishes, manages, and terminates sessions between applications on different devices.
6. Presentation Layer: Translates data between the application format and the network format, handling encryption, compression, and character encoding.
7. Application Layer: Provides network services directly to user applications, such as HTTP, FTP, and SMTP.

Wireless transmission refers to the transfer of information between two or more points that are not connected by an electrical conductor. It utilizes the electromagnetic spectrum to propagate signals through free space.

Key components and technologies include:

• Radio Waves: Used for long-distance communication, including FM/AM radio, television, and mobile networks. They are omnidirectional and can penetrate buildings.
• Microwaves: High-frequency waves used for point-to-point communication, satellite links, and Wi-Fi. They require line-of-sight propagation and are susceptible to atmospheric interference.
• Infrared: Used for short-range communication, such as remote controls and local data exchange. It cannot penetrate walls, providing inherent security for short distances.
• Challenges: Wireless signals face significant hurdles including attenuation (signal weakening over distance), interference from other electronic devices, multipath propagation (reflections causing echoes), and security vulnerabilities due to the open nature of the medium.