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- 2071 Chaitra · 2 marks
- 2070 Asar · 3 marks
Multiple access protocols
Short answer
Multiple access protocols are MAC rules for sharing a channel: random access (ALOHA, CSMA/CD) with collision handling, controlled access (polling, token passing) with turns, and channelization (FDMA, TDMA, CDMA) dividing the medium.
What are multiple access protocols? How can a multi-access channel be shared by different nodes?
Multiple access protocols
When many nodes share a single broadcast channel, collisions can occur if two nodes transmit at the same time. Multiple access protocols are the rules in the MAC sublayer that decide which node may use the shared channel and when, so that the channel is used efficiently with few or no collisions.
How a multi-access channel is shared
Multiple access protocols
|- Random access : ALOHA (pure, slotted), CSMA, CSMA/CD, CSMA/CA
|- Controlled access : Reservation, Polling, Token passing
|- Channelization : FDMA, TDMA, CDMA
- Random access: no station is in control; each sends when it has data and resolves collisions by retransmitting after a random wait. Examples: ALOHA, CSMA/CD (Ethernet), CSMA/CA (Wi-Fi).
- Controlled access: stations take turns, so no collision. Methods: reservation (reserve a slot before sending), polling (a master asks each station) and token passing (the station holding the token sends).
- Channelization: the channel is split by frequency (FDMA), time (TDMA) or code (CDMA) and each station gets a fixed share.
✓ Answer checked by Claude Opus 5.5 (high effort)
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