Municipal Wi-Fi Network Surveying and Testing: Part III
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Part one of this series introduced municipal Wi-Fi surveying and testing performed by independent testers, including the typical phases, and how to get prepared for each. Then part two began by detailing how to build a muni wireless toolkit, and jumped into performing a Pre-Installation Survey. This tutorial will conclude the series by discussing how to perform the Pilot and Acceptance Testing phases.
As discussed in the earlier parts, Pilot Testing is performed to help pick between competing solution providers. Acceptance Testing is performed after a municipal network is installed to determine if the solution provider has met the technical requirements and if the network is ready to be turned over to the city or other owner. The testing and surveying tasks for each of these phases are very similar; however Acceptance Testing should be more in-depth and could be performed with more accurate testing techniques and tools.
- Review and analyze plans. The solution providers network designs and installation plans should be reviewed by the independent testers for suitability and efficiency, and they should discuss the findings in the report. For example, the following could be factored in:
- Wireless standards used for the nodes and backhaul equipment. For instance, they would discover if dual-radio nodes are used and note the frequencies used. Plus, they should discover the frequencies used by the backhaul equipment and if it would have any impact on the municipal network.
- Number of nodes per square mile. The independent testers could also compare the amount of nodes used by the solution provider to the amount recommended by the equipment vendor, and investigate if a discrepancy is found. More modes may be required to cover areas that are RF unfriendly, usually due to more (tall) buildings, trees, and hills. However if they see the solution provider is using more nodes inefficiently, they should note this for the report.
- Perform the drive survey. While driving about one-mile increments in the intended coverage area, the independent testers should simultaneously:
- Scan for wireless networks. In order for them to verify wireless coverage and signal quality, theyll need to do a drive survey of the coverage area. Then they can compare the Signal-to-Noise Ratio (SNR) values seen in the coverage area to the required values. The setup for this type of surveying was discussed in part two of this tutorial series.
- Observe mounting assets. During the drive survey, they should keep an eye out for the mounting assets used. Plus they should pay attention to the placement of the nodes on the mounting assets. Generally, for the most effective coverage its recommended to place nodes as close as possible to the middle of streets, for instance on horizontal traffic light poles or the end of the arms of typical street lights. The independent tester should analyze if the mounting assets and node placements are effective for the given area and the particular nodes. They might even take pictures of the different mounting asset and placement types to include in the report.
- Observe the environment. They should pay attention to the environment, particularly its potential (positive or negative) impact on the municipal network, such as the amount of tall buildings, dense foliage or trees, or highly or lightly populated areas. Then later they can compare how well the solution providers did in getting the required coverage and signal levels to the level of challenge provided by the environment of the area.
- Test network performance. Though performance results vary depending upon the networks current usage, the independent testers should still perform some throughput and latency tests during the Pilot and Acceptance Testing phases; which could involve the following:
- Perform ping tests. Ping all the nodes through one or more node. If performing Pilot Testing, they should compare the results between each pilot area.
- Perform roaming latency tests. This is to measure the suitability of high-performance applications, such as VoIP or VoWLAN. One way they can do this is by connecting to a server, located at the backhaul of the network, while capturing the packets with a WLAN analyzer. Then they can start traveling through the coverage area, while connected to the server. When theyre done, they could examine the packet traces to find out the delay between roaming from one node to another, and compare it to the times recommended for the application.
- Perform active throughput tests. They can run these tests against multiple nodes throughout the area with your WLAN analyzer.
- Verify the networks back-up power capabilities. With the cooperation of the city and solution provider, the independent testers can schedule a time to have the power cut from the nodes. Then they could simply verify that the network and nodes are operational for at least the required time period.
- Evaluate the technical aspects of any proposed solutions for city, public, or safety applications. This can include their predications of the applications performance and impact on the network.
When the independent testers are done, theyll need to compile the report. In the report, the surveying and testing methodology should be stated, along with their findings and recommendations. This should include the averages, maximums, and minimums of the municipal networks signal and signal-to-noise ratio levels captured with the WLAN analyzer. Then they should compare the captured values to the required levels. They should also report on the network design and installation plans (discussed in Step 1), and then discuss the results of their performance tests.
Finally, the independent testers should give any recommendations that may help the networks performance and efficiency, and indicate whether the solution provider has met the requirements.
Eric Geier is an author of many wireless networking and computing books including Home Networking All-in-One Desk Reference For Dummies (Wiley 2008) and Wi-Fi Hotspots: Setting up Public Wireless Internet Access (Cisco Press 2006).