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Category: WLAN general

All posts on the topic of Wireless LANs including 802.11 standards, Wi-Fi alliance etc. that are not related to any specific WLAN vendor

WPA2-Personal Encryption is Now Pointless.

WPA2-Personal Encryption is Now Pointless.

  “It is a secret in the Oxford sense. You may tell it to only one person at a time.” – Lord Franks (1905-1992) English academic, diplomat and philosopher   SHA-1 In the world of telecommunications and technology, nothing lasts forever.  When it comes to the issue of security, nothing is ever truly secure and nothing stays unbroken. Consider the case of good old Hashing Algorithm SHA-1.  For years researchers have been warning that SHA-1 is weak, and have been actively urging people not…

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Is LTE-U Really Wi-Fi’s Great Challenger?

Is LTE-U Really Wi-Fi’s Great Challenger?

So I will admit I am writing this in a fit of pique.  Today Bloomberg published this preposterous piece of marketing flimflam claiming that LTE-U has the potential to replace or drown out Wi-Fi.  I am not sure if the consultants quoted in that article are drinking kool-aid together, but I certainly feel like they have missed some key points. So I am going to ask one very simple question: What does LTE-U enable that Wi-Fi doesn’t? Answer: The ability…

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Using the ODROID C2 as a WLAN Testing Tool – Part 3: Some Exploring and Installing wicd

Using the ODROID C2 as a WLAN Testing Tool – Part 3: Some Exploring and Installing wicd

Previous Articles in this series: Install & Preconfigure DietPi DietPi, First Boot In the previous posts in this series I took a look at how I installed and configured DietPi on my ODROID C2.  I also went through the settings and some software packages that I wanted to install on the first boot.  I should re-iterate here that one of the goals of this series is not to blandly show the reader how to do things, but also to try…

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Using the ODROID C2 as a WLAN Testing Tool – Part 2: DietPi, First Boot

Using the ODROID C2 as a WLAN Testing Tool – Part 2: DietPi, First Boot

In the Previous Post,  I went through the basic steps of installing DietPi on an SD Card / eMMC card using the MAC OS terminal and preparing the network settings for the first boot.  If you are reading this post, you should have DietPi installed on your eMMC / SD Card and it is time to boot your SBC for the first time (if you haven’t already).   As a reminder, I am using the ODROID-C2 and will just refer to…

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Using the ODROID C2 as a WLAN Testing Tool – Part 1: Install & Preconfigure DietPi

Using the ODROID C2 as a WLAN Testing Tool – Part 1: Install & Preconfigure DietPi

This series is inspired by the “Maker Session” conducted at the WLAN Pros Conference last year in Budapest.  During the Maker Session each one of the attendees was given an ODROID C2  single board computer along with a battery pack and various other accessories including an 8GB eMMC , eMMC reader, WLAN Adapter etc.  The session went through the steps of installing a customised image of DietPi that included some very handy WLAN tools included in it.  You can see…

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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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802.11 PHY Compatibility – Basic Overview

802.11 PHY Compatibility – Basic Overview

802.11g <–> 802.11 / 802.11b: When 802.11g (ERP-OFDM) was released in 2003, we needed a way to co-exist with the large installed base of older 802.11 (DSSS) and 802.11b (HR-DSSS) based networks and equipment out there.  The solution to the problem used RTS/CTS control frames to silence the channel before an 802.11g station used any of the higher modulations.  Before transmitting a frame using OFDM modulation, the transmitting station would initiate an RTS / CTS exchange with the receiving station.  The RTS/CTS…

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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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