Medium Access Control Protocols
a day ago
- #Communication Protocols
- #Medium Access Control
- #Wireless Networks
- Medium Access Control (MAC) protocols are essential for managing communication in shared mediums to prevent message collisions.
- ALOHA was the first random-access MAC protocol, using two frequencies to separate data and acknowledgments, with random delays for retransmissions after collisions, achieving up to 18.4% efficiency.
- Ethernet improved on ALOHA by using CSMA/CD, allowing nodes to listen before transmitting and detect collisions immediately, with exponential backoff to adapt to network size.
- WiFi employs CSMA/CA with a single frequency, using DIFS and RTS/CTS packets to handle hidden node problems and prioritize acknowledgments from the router.
- Cellular networks use orthogonal multiple access schemes like FDMA, TDMA, and CDMA, with cell towers scheduling resource blocks to minimize collisions, except during initial random-access registration.
- Mesh networks, such as those in SURAN, Bluetooth Mesh, Zigbee, and LoRa, operate without infrastructure, using various strategies like spread spectrum, CSMA/CA, and simple ALOHA for low-power or dynamic environments.
- Other protocols include hybrid TDMA-CSMA, MACA, Q-CSMA, Busy Tone, DDMC-TDMA, and KAMA, each addressing specific network challenges like hidden nodes, traffic types, and decentralized scheduling.