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

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

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.