https://youtu.be/e7RsGq0NOnE?si=FNbaeAQRjv-Av3xp

Introduction

Ad hoc wireless networks operate without a centralized infrastructure, relying on a distributed set of nodes that share a common broadcast radio channel. The limited bandwidth available, along with the dynamic nature of such networks, necessitates the design of specialized Media Access Control (MAC) protocols. These protocols aim to efficiently manage access to the shared medium, addressing unique challenges such as node mobility, hidden and exposed terminal problems, and the error-prone nature of wireless communication.

Key Design Issues of MAC protocols

1. Bandwidth Efficiency

• Definition: The ratio of bandwidth used for actual data transmission to the total available bandwidth.
• Goal: Maximize bandwidth efficiency by minimizing control overhead and optimizing data transmission.

2. Quality of Service (QoS) Support

• Challenge: Node mobility complicates QoS, as bandwidth reservations may become invalid with node movement.
• Requirement: Protocols must include mechanisms for QoS support, particularly for time-critical traffic.

3. Synchronization

• Importance: Time synchronization among nodes is crucial for bandwidth reservations and efficient communication.
• Method: Synchronization may require the exchange of control packets, which should be optimized to minimize bandwidth consumption.

4. Hidden and Exposed Terminal Problems

• Hidden Terminal Problem: Collisions occur when nodes outside each other’s transmission range send packets simultaneously to a receiving node.
• Exposed Terminal Problem: A node unnecessarily refrains from transmitting because it detects a nearby transmission, even though it wouldn't cause a collision.
• Impact: These problems reduce network throughput, especially under high traffic conditions.

5. Error-Prone Shared Broadcast Channel

• Nature: The broadcast nature of wireless channels leads to potential packet collisions.