Explain the different design issues for Wireless MAC protocol with certain ex- amples.

  1. Channel Access: How devices share the wireless channel to transmit data.
    • Example: CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) used in Wi-Fi, where devices listen for a clear channel before transmitting to avoid collisions.
  2. Collision Handling: Dealing with data collisions when multiple devices transmit simultaneously.
    • Example: CSMA/CD (Carrier Sense Multiple Access with Collision Detection) used in Ethernet, where collisions are detected and resolved by retransmitting.
  3. Contention vs. Scheduled Access: Deciding between letting devices contend for the channel or scheduling access.
    • Example: Contention-based protocols like CSMA for dynamic networks, vs. TDMA (Time Division Multiple Access) for fixed schedules in cellular systems.
  4. Hidden Terminal Problem: Addressing situations where devices can’t hear each other.
    • Example: Using RTS/CTS (Request-to-Send/Clear-to-Send) exchange in Wi-Fi to prevent hidden terminal collisions.
  5. Exposure Problem: Avoiding excessive interference caused by nearby transmissions.
    • Example: WiMAX uses beamforming techniques to direct signals towards specific devices, reducing exposure to unrelated devices.
  6. Energy Efficiency: Maximizing device battery life while maintaining effective communication.
    • Example: Zigbee uses low-duty cycle and sleep modes to save energy in sensor networks.
  7. Quality of Service (QoS): Prioritizing traffic based on application requirements.
    • Example: IEEE 802.11e (Wi-Fi QoS Extension) introduces QoS classes for different traffic types like voice and video.
  8. Security: Preventing unauthorized access and data breaches.
    • Example: WPA2/WPA3 in Wi-Fi use encryption and authentication to secure communications.
  9. Backoff Mechanisms: Defining rules for devices to wait before retrying after collisions.
    • Example: Ethernet uses binary exponential backoff to reduce collisions in shared media networks.
  10. Frame Format: Structuring data frames for efficient transmission and reception.
    • Example: Wi-Fi frames include headers for addressing, control, and error-checking information.