Which multiple access technique is used by ieee 802.11 standard for wireless lan?

General
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which multiple access technique is used by ieee 802.11 standard for wireless lan?

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Which multiple access technique is used by IEEE 802.11 standard for wireless LAN?

Answer:
IEEE 802.11 standard for wireless LAN, commonly known as Wi-Fi, utilizes a multiple access technique called “Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA).” This technique is specifically designed to manage how devices access the shared wireless medium to avoid collisions and ensure efficient communication.

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA):

  1. Carrier Sense (CS): Before transmitting data, a device using CSMA/CA listens to the wireless medium to detect if it is busy (i.e., if other devices are transmitting). If the medium is idle, the device waits for a short Interframe Space (IFS) duration before starting its transmission. If the medium is busy, the device defers its transmission and continues to listen until it becomes idle.

  2. Multiple Access: Multiple devices can contend for access to the wireless medium. When multiple devices attempt to transmit simultaneously, collisions can occur. CSMA/CA aims to minimize collisions by employing a contention-based access mechanism.

  3. Collision Avoidance (CA): Instead of detecting collisions like in Carrier Sense Multiple Access with Collision Detection (CSMA/CD), CSMA/CA focuses on avoiding collisions. It achieves this by using a mechanism known as the Distributed Coordination Function (DCF), which includes a process of random backoff. After sensing that the medium is idle, devices select a random backoff interval before initiating transmission. This random backoff reduces the likelihood of collisions, as devices are less likely to choose the same transmission slot.

  4. Acknowledgment (ACK): After successfully receiving a frame, the receiving device sends an acknowledgment frame (ACK) to the sender. If the sender does not receive an ACK within a specified timeframe, it assumes that the frame was not successfully transmitted and retransmits it.

By employing CSMA/CA, the IEEE 802.11 standard ensures efficient and reliable communication in wireless LAN environments, effectively managing the shared medium and minimizing the occurrence of collisions, which can degrade network performance.