sfi

NDP

ENTERPRISE IRELAND

NCNRC

Communications Network Research Institute

WLAN Resource Monitor (WRM)

Mark Davis

The WRM application allows the user to analyze the performance of the stations in terms of their bandwidth utilization and availability. For example, it is possible to monitor the percentage utilization of the available capacity for each station (and its associated access categories). The screenshot below shows how this measurement is presented as a series of meters that allow the user to quickly determine station performance.

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The WRM application supports the B, G, and A modes and includes IEEE 802.11e/WMM QoS operation where the network bandwidth measurements for each of the four defined access categories (ACs) are presented in real time and on a per node basis. The ACs are defined as Best Effort (BE), Background (BK), Video (VI) and Voice (VO). Associated with each of these ACs is a set of EDCA parameters (AIFSN, ECWmin, ECWmax) that determine how the AC contends for access via the MAC mechanism. By appropriately setting the EDCA parameters for each of the ACs, it is possible to prioritize the manner in which they access the medium.


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The screenshot shows the wealth of detailed information related to the network bandwidth measurements that the WRM application can provide to network managers.


A brief overview of the theoretical basis of the WRM application as well as some of the technical details regarding its implementation is given in the following presentation.

Download Presentation (0.9 MB)

Obtaining a Copy of the WRM Application

A demo version of the WRM application that runs under Microsoft Windows XP and Vista is now available. The application has been designed to operate with the AirPcap wireless packet capture adapter (i.e. a Wi-Fi sniffer tool) from CACE Technologies Inc. The AirPCap Ex adapter is recommended for use with the WRM application.

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Please click here to download a demo version of the WRM application.

Note: In order to use the WRM application, it is necessary to first install the AirPCap driver from CACE Technologies Inc.

The installation package contains the following:

A FAQ on the WRM application may be obtained by clicking on the following link WRM FAQ.

The latest version of the WRM (version 1.1) is compatible with the Wireshark Network Protocol Analyzer. Captured WLAN packets from Wireshark can be exported to a file which can be read by the WRM to provide for valuable L2/MAC peformance metrics.


WRM API

At the heart of the WRM application is a piece of software (the WRM engine) that processes the wireless frames captured by the WLAN adapter. The WRM has been realized as an API that allows new applications to be quickly developed. The API is available as a portable C/C++ shared library (~300 kB) which a developer links to when building a new application. The API supports both the Windows and Linux OS environments. The details of the WRM engine are hidden from the developer and its operation is controlled through a small number of functions and the network bandwidth measurements are returned through a standardized data structure.

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