TamoSoft: Network Analysis Tools & Security Software
Contents

Site Survey Tool - TamoGraph
 
Introduction
Overview
Why to Perform a Site Survey
When to Perform a Site Survey
Survey Types
System Requirements
Driver Installation
Driver Installation Troubleshooting
Trial Version Limitations
License Types
Interface Overview
Access Point List
Floor Plan / Site Map
Plans and Surveys, Properties, and Options Panel
Main Menu
Performing a Site Survey
New Project Wizard
Calibration
Configuration
Data Collection
Understanding Survey Types: Passive vs. Active
Active Survey Configuration
Best Practices, Tips, and Tricks
Survey Job Splitting
Analyzing Data – Passive Surveys
Selecting Data for Analysis
Adjusting AP Locations
Splitting an AP into Multiple Unique APs
Visualization Types
Signal Level
Signal-to-Noise Ratio
Signal-to-Interference Ratio
AP Coverage Areas
Number of APs
Expected PHY Rate
Frame Format
Channel Bandwidth
Requirements
Analyzing Data – Active Surveys
Selecting Data for Analysis
Visualization Types
Actual PHY Rate
TCP Upstream and Downstream Rate
UDP Upstream and Downstream Rate
UDP Upstream and Downstream Loss
Round-trip Time
Associated AP
Requirements
Reporting and Printing
Customizing Reports
Google Earth Integration
Configuring TamoGraph
Plans and Surveys
Properties
Plan / Map
Environment
Requirements
Scanner
Options
Colors and Value Ranges
AP Detection and Placement
Visualization Settings
Miscellaneous
Configuring GPS Receiver
Using GPS Configuration Dialog
Finding the GPS Receiver Port Number
Frequently Asked Questions
Sales and Support

Channel Bandwidth

This visualization shows what type of channel bandwidth (also called channel width) is being used in the given WLAN area. Wi-Fi networks use three types of channel bandwidth:

§20 MHz Legacy: This is a legacy type used by 802.11 a/b/g equipment that is not based on the latest 802.11n standard. Each channel occupies 20 MHz of radio spectrum.
§20 MHz HT: This is a new frame format introduced in the 802.11n standard. It occupies the same 20 MHz spectrum space as the legacy equipment, but uses HT-mixed and HT-Greenfield frame formats.
§40 MHz HT: This is a new frame format introduced in the 802.11n standard. It uses two 20 MHz channels simultaneously, thus occupying 40 MHz spectrum space. This technology is often referred to as “channel bonding.” It also uses HT-mixed and HT-Greenfield frame formats.

Channel bandwidth is shown for the AP that has the strongest signal in the given map area among the APs selected for analysis. This mimics the roaming behavior of client adapters that connected to the strongest AP. While other audible APs may offer other types of bandwidth, a typical adapter will connect to the AP with the strongest signal. You can deselect one or several of the selected APs to see channel bandwidth types for less strong APs.

Double-clicking on the Channel Bandwidth legend on the status bar allows you to configure the color scheme and change its value range.

Suggested Solutions

 

If you see 20 MHz Legacy or 20 MHz HT channel bandwidth in the areas where you expect to see 40 MHz HT, the following solutions are suggested:

§Check your AP configuration. If you are using newer 802.11n equipment, make sure that it is configured to use 40 MHz or automatic 20/40 MHz channel width.
§Your AP's ability to use 40 MHz channels depends on the wireless environment. A 40 MHz-enabled AP may fall back to 20 MHz mode in some situations (e.g., when an 802.11n client that does not support 40 MHz bandwidth is connected). Because of the changing environment, the site survey results regarding the channel bandwidth may change from time to time. Perform site surveys regularly.
§If you are using legacy 802.11 a/b/g equipment, consider upgrading to 802.11n.