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Author: Rob Krumm

SETTING MINIMUM DATA RATES? – READ THIS FIRST.

SETTING MINIMUM DATA RATES? – READ THIS FIRST.

  Nowadays when you speak with a WLAN professional you will often hear the suggestion of setting or restricting minimum PHY rates to optimise your WLAN’s  performance.  Many professionals nowadays consider this to be one of the basic tasks that must be completed in the process of configuring and optimising a WLAN. Configuring the minimum rates in a WLAN can have many benefits to your network’s performance including reduction of management overhead, removal of unnecessary RTS/CTS frames, better airtime utilisation, and enhanced throughput…

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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.