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Tag: Wi-Fi

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

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 series, my intention here is to build an argument and the logic for describing what WLAN contention actually looks like in the real world.  We’ve…

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

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 of CSMA/CA. When two (or more) 802.11 stations both have data to send on the same channel and both have established that the channel is…

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What Does 802.11 Contention Look Like? (Part 1)

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 occurring between two stations increases seemingly exponentially with the number of active stations contending for the wireless medium.  This means that as more and more…

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Wi-Fi CSMA/CA – Going Deep

Wi-Fi CSMA/CA – Going Deep

In my career as a Wireless Engineer I have read a whole bunch of articles on Wireless Arbitration and how it works and to be perfectly honest, I have not ever really looked deep enough to fully understand how the carrier medium is actually marked as busy by the PHY and MAC layers. I learnt pretty early on that at the beginning of the transmission of a frame, there is a field somewhere that tells all the other stations to…

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The Great WLAN Vendor Consolidation of 2015?

The Great WLAN Vendor Consolidation of 2015?

So. One of the things I have been thinking about recently is the state of many Enterprise WLAN Vendors in the marketplace. Before I go any further I should  state that any of the opinions I express here are purely my own and I am not speaking for anyone else apart from sharing my own personal musings on the topic. So don’t take this too seriously.