Episode Archives

CTS 162: 802.11ax OFDMA Subcarriers

With OFDMA in 802.11ax, the size of the subcarriers has been divided by 4. Going from 312.5KHz wide with OFDM to 78.125KHz wide. The symbol duration has been increased by 4 times in the meantime. Going from 3.2 microseconds with OFDM to 12.8 microseconds. View the full image here Advantages of having more subcarriers Allow...

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CTS 161: 802.11ax BSS Coloring

Why is there a need for BSS Coloring? To help a receiving device identify the BSS from which a receiving PPDU originates from so that there’s a reduction in BSS collision reporting a busy medium. 802.11ax allows the medium to be reused more often between OBSSs by identifying those overlapping BSSs. The primary purpose is...

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CTS 160: 802.11ax OFDMA Resource Units

802.11ax (Wi-Fi 6) brings OFDMA to wireless. It’s an enhancement over OFDM which was a single-user transmission.  When a signal is sent or received it is done with one device. In OFDMA, it allows multiple access which means simultaneous transmissions to/from multiple devices. There is a downlink multi-user operation and an uplink multi-user operation. In...

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CTS 159: Wi-fi 6 (802.11ax) Overview

I decided to finally get myself a little familiar with 802.11ax. I’m not sure why but I’ve pretty much ignored it until now. In this episode, I’m going to provide my overview of 802.11ax, or Wi-Fi 6. This episode will be the start of a mini series diving into detail of the components of 802.11ax....

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CTS 158: 802.11w – Management Frame Protection

802.11w applies to robust management frames protected by Protected Management Frame (PMF). Wireless environment includes: Rogues Susceptible to eavesdropping Data traffic is usually encrypted Management frame is usually unencrypted Goal of 802.11w is to protect management frames from forgery or spoofing. I see it all the time in San Francisco. Deauthentication attacks coming left, right,...

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CTS 157: The effect of rate limiting on Wi-Fi

Welcome to a new episode where we speak with Troy Martin. We’re following his presentation at WLPC Prague, Effects of Rate Limiting on Wi-Fi Flow. We ask Troy to go into more detail about rate limiting and the effect it has on Wi-Fi. Effect Of Rate Limiting on Wi-Fi Users often goes around obstacles. What...

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