Author: Neftaly Malatjie

Signal coverage testing is often part of performing a wireless site survey and should be done before installing the WLAN. This is done by positioning a test access point at various locations throughout the required coverage area and using a signal meter to measure signal values in the vicinity of the test access point. The results of this propagation testing provide a basis for making decision on where to install access points.

Testing Signal coverage testing involves using a signal coverage tester (sometimes referred to as a signal meter) to measure WLAN signals throughout the coverage areas. The main objective is to ensure that signal levels are high enough to support the levels of performance that the users need when using applications over the WLAN.

When planning the testing of a WLAN, consider the following forms of testing:

• Signal coverage testing: Signal coverage testing determines where client devices are able to satisfy coverage requirements. This testing may be part of performing a WLAN site survey or done after the network is installed to determine the as-installed signal coverage.
• Performance testing: Performance testing determines whether the WLAN can satisfy user needs for using specific applications over the WLAN.
• In-motion testing: In-motion testing determines whether users can continue to make use of applications while roaming throughout the coverage areas, especially when the roaming requires handoffs between access points.
• Security vulnerability testing: Security vulnerability testing ensures that the WLAN implements required security mechanisms and offers sufficient protection to unauthorized access and passive monitoring.
• Acceptance/verification testing: After installing a WLAN, it is important to run a series of acceptance/verification tests to ensure that the WLAN satisfies all requirements. This is especially important if the organization is having a contractor install the WLAN.
• Simulation testing: In some cases, such as when implementing a very large WLAN, it may be beneficial to simulate the behaviour of the WLAN before actually installing it. This can provide helpful feedback when designing the system, especially if the WLAN will have critical performance requirements.
• Prototype testing: Prototype testing involves implementing an individual function of the WLAN that is not well understood before deploying the complete system. For example, an organization may not be very familiar with 802.1X authentication systems and may benefit by implementing the 802.1X authentication in a lab environment with a limited number of test client devices.
• Pilot testing: Before installing the WLAN across the entire organization, which may include numerous buildings and different applications, it is strongly advisable to install the system in a limited number of facilities (ideally one) and make that one work effectively first. After you work out all the problems, you can install the WLAN at the remaining location without the need for extensive rework because the problems will likely have been solved during the pilot testing.

Simulation uses software models that artificially represent the network’s hardware, software, traffic flows, and use. You can run simulations that replay or generate various types of traffic or protocol streams to validate results quickly; days of network activity go by in minutes when simulating traffic using such tools. Currently available simulation tools can assist a designer in developing a simulation model. Most simulation tools represent the network using a combination of processing elements, transfer devices, and storage devices. Simulation tools are generally costly, with prices in the tens of thousands of dollars. You might be better off hiring a company that already owns a simulation tool.

The main attributes of using simulation to verify the technologies are the following:

• Results are only as accurate as the model; in many cases, you will need to estimate traffic flows and utilization.
• After building the initial model, you can easily make changes and rerun tests.
• Simulation does not require access to network hardware and software.
• It does not require much geographical space, just the space for the hardware running the simulation software.
• Simulation software is fairly expensive, making simulation not economically feasible for most one-time designs.
• The people working with the simulation program will probably need training.

Consider using simulation for the following situations:

• When developing a type of WLAN product that does not yet exist
• When it is not feasible or possible to obtain applicable WLAN hardware and associated software for testing purposes
• When testing performance requirements based on predicted user activity (because it is often not practical to do this with physical prototyping)

When it is cost-effective to maintain a baseline model of a product or system to test changes to the baseline