Testing indoor signal coverage

A while back, in one of my posts, I’d discussed methods for maximizing the testing of municipal networks within indoor areas. A problem is that often system integrators performing system testing and the municipalities completing acceptance testing don’t have access to all indoor establishments, such as homes and private businesses. So how can you adequately determine if indoor signal coverage meets requirements if you don’t have access to all facilities? Believe me. You’ll be facing this question sooner or later.

Probably the best you’ll be able to do is to estimate indoor signal coverage. One method is to develop simulation models that depict, as close as possible, the city environment. Simulation can estimate indoor coverage fairly well, but you’ll need to spend a great deal of time building the model due to a somewhat steep learning curve when initially using the tools and methods necessary to precisely render the city environment. Just be sure to weigh the costs of doing simulation and understand that the results will be an estimation that’s only as good as the model provides. If you do invest in simulation, it’s crucial that you measure signal coverage at sample indoor locations throughout the municipality to confirm that the simulation is offering valid results.

Another way of verifying indoor coverage is to test as many indoor locations as practical, and use the test results to gain a solid understanding of the typical attenuation offered by different types of facilities. You may consider calculating an average attenuation value for the entire city or determine different attenuation values for each major area type, such as residential, business parks, downtown streets, etc. You can then combine the attenuation data with outdoor coverage test results in order to estimate what coverage you’ll have inside the facilities. Most outdoor signal coverage test tools allow you to include attenuation factors in order to scale what is indicated on coverage maps. So, this process allows you to generate an indoor coverage map from an outdoor one, and it doesn’t take much time to complete. The problem is that you’ll still have some inaccuracies (maybe not enough to worry about) because you’re estimating the attenuation values.

– – – – –

Jim Geier is an independent consultant and founder of Wireless-Nets, Ltd (www.wireless-nets.com), a consulting firm assisting municipalities, enterprises, hospitals, airports, and equipment providers with the development and deployment of wireless networks. Jim is the author of several books, including Deploying Voice over Wireless LANs (Cisco Press), Wireless LANs (SAMS), Wireless Networks First Step (Cisco Press), Wireless Networking Handbook (Macmillan), and Network Reengineering (McGraw-Hill).

Comments

  1. Drew Lentz says:

    I agree with the methodology of this article, but would like to add one critical piece. After completing your assessment and assignment of attenuation data, make sure that you go back and test those numbers.

    It is easy to assign attenuation to specific types of building materials, clutter areas, foliage, etc. in most propagation applications, but for the best real-world numbers, assign that data and then double-check it. This will help you get around the inaccuracies and give you a better feel of what types of signals can bleed through what types of materials!