Medium Access

What does 802.11 Contention Look Like (Part 3) – Probabilities & Our First Model

In my previous blog posts in this series I covered the inherent problem with CSMA/CA and how it loses efficiency as more stations make use of a channel.  I also covered some of the basic rules of how CSMA/CA works as implemented by 802.11 Wireless LANs. As I mentioned at the beginning of this blog […]

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What Does 802.11 Contention Look Like (Part 2) – How contention works:

802.11 Medium Access Control implemented with the Distributed Co-ordination Function (DCF) and Enhanced DCF Channel Access (EDCA) methods, uses a random back-off counter to help ensure that clients do not transmit their data at the same time, but rather take turns to send their data one after the other.  This is the “Collision Avoidance” part […]

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What Does 802.11 Contention Look Like? (Part 1)

The IEEE 802.11 Wireless LAN protocol uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) with a fairly robust arbitration mechanism to allow WLAN Stations (STAs) to gain access to the wireless medium based on their traffic priority. The central problem with CSMA/CA and the 802.11 arbitration mechanisms is that the chances of a collision […]

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