Continuing with this blog series, the concept map for this week is about the 802.11 MAC Sublayer. The map presents the basics of the 802.11 MPDU format, including types of frames, MAC addressing, frame fragmentation, and QoS capabilities.

Click to Enlarge

Last week I started this blog series where, as part of my study routine for the CWAP certification, I intend to build various concept maps to summarize each of the major topics of the official CWAP study guide and share them with the WLAN community. The concept map of this second part is about the 802.11 Physical (PHY) Layer:

Last year I became a Certified Wireless Network Administrator (CWNA), and doing so showed me that I really didn't know about wireless networks as well as I thought, even though I work with them everyday.

The design of WiFi Explorer aims to make it easy for non-technical users to troubleshoot home or a small office wireless networks, but also to provide IT and WLAN professionals a tool for preliminary assessments and troubleshooting of larger and more complex networks such as the those found in enterprise environments. Here's a list of features in WiFi Explorer you might find useful when it comes to troubleshooting wireless networks.

A few weeks ago I released Airtool, a simple menubar app for OS X that allows you to easily perform 802.11 frame captures on a single or multiple channels. One of the options in Airtool lets you configure the link-layer header type you want to capture as part of the frames. In this blog post I'm going to give a brief description of the header types that are available for the built-in Wi-Fi adapter on a Mac so you can understand the differences and choose the right header type for your captures.

Here are some ideas on how to improve your home Wi-Fi:

1. Check the placement of your access point (AP).
A location that is higher and to the center of the house should give the best coverage.

2. Do a quick survey and choose a wireless channel that is less occupied.
For 2.4 GHz networks consider using channels 1, 6, or 11, to avoid overlapping. As for 5 GHz, the channels are spaced further apart so overlapping is less of an issue.

Normally, you connect to an AR.Drone using its Wi-Fi interface, but if for some reason this is not working, you can open a serial console to do any necessary fixes or simply have a permanent connection to the device for debugging, for example. To open a serial console, you will need a USB to UART connector, a USB extension (optional) and some wires. Although there might be other USB to UART bridges that would work fine, I have only used the CP2102 bridge from Sillicon Labs (Amazon, $6.97).

(USE THESE INSTRUCTIONS AT YOUR OWN RISK)

Today I came across this article titled How to Find the Best Wi-Fi Chanel with Wireless Diagnostics in Mac OS X that basically explains how to use the bundled Wi-Fi scanner that comes with OS X Mavericks to choose the best channel for your wireless network.

Every now and then I'm told by users of WiFi Explorer that the app does not detect "hidden" networks. Unfortunately, this is true. The CoreWLAN framework used by WiFi Explorer, and other similar apps in the Mac App Store, does not provide any information from networks that have been configured to not broadcast their SSID or network name. WiFi Explorer will, however, find and display the information of a hidden network if you're connected to it, but if that's not the case, nothing will be shown.