MAC Protocols in Wireless Networks:
MAC protocols manage access to the wireless channel in wireless networks. They determine how devices compete for and use the channel to send data efficiently.
Challenges in Wireless Networks:
- Hidden terminal: Nodes can’t hear each other but can talk to a central point.
- Exposed terminal: Nodes avoid transmitting due to interference.
Types of MAC Protocols:
1. Fixed Assignment:
- Allocates specific time slots or frequencies to nodes.
- Ensures no collisions but can be inefficient if nodes are idle.
2. Random Assignment:
- Nodes contend for the channel using random access methods.
- Listens for ongoing transmissions before sending.
- Backs off for random time if channel is busy.
- Example: CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance).
- Mixes fixed assignment and random access.
- Nodes request channel access in a reservation phase.
- Data transmission phase follows reservation.
- Example: RTS/CTS (Request-to-Send/Clear-to-Send) in IEEE 802.11.
Choosing the Right MAC Protocol:
- Depends on network requirements and trade-offs.
- Efficiency vs. complexity.
- Consider hidden/exposed terminal issues and overall network performance.