10 Mar

Designing For Success

By Ryan McCaigue

Building a municipal wireless network at first feels like a daunting task. There are many obstacles to avoid, technologies to consider, and decisions to make. Not many municipalities have the expertise in engineering and RF design staff to facilitate the construction and integration of a wireless network. Finding an experienced partner, trusted adviser is critical to your success.

Municipal wireless networks are capable of supporting a wide range of applications. Each application to be run on the network must be considered in the design of the network so that no one application has a negative impact on the overall performance. I recommend that a municipality start with a thorough review of the applications that are being considered. This involves a great deal of discussion with stakeholders likely to use the network.

A few of the more common stakeholders:
Public Transit
Municipal Workers
Public Access

Start with a thorough assessment of your application needs. Meet with stakeholders to explore the opportunities and costs involved in deploying a municipal wireless network. Working to build consensus among various departments and constituents to ensure the broadest possible adoption of the network.

Designing the network requires establishing clear goals and expectations for the applications to be run on the network followed by assessing the impact of those applications on the network design.

Starting with requirements for each application, engineer a solution to meet those requirements. Find an engineering team, independent design firm that does not sell equipment or profit from the selection of one vender over another. One who has worked with a wide variety of vendors in the Municipal market. Focus on standards-based, cost-effective, reliable, time-tested solutions.

Designing a municipal wireless network is more than simply a “Dixie Cup Exercise”.

I’ve seen a number of consultants and vendors doing great disservice to their clients by not doing an appropriate professional, detailed RF design. You can’t simply rollout a map and draw circles on it to predict the propagation of radio frequency energy. You can’t simply say it will take 40 nodes per square mile to provide ubiquitous coverage.
Each municipality has its own unique challenges, terrain, trees, buildings, and other sources of RF interference. Each requires a detailed site surveys, interference testing, and propagation modeling for every radio and client.

Right is a sample of a 900+ node network. This heat map shows the propagation of the 4.9 public safety within the terrain. The goal of this network was to establish 95% street level coverage for public safety. Trees in this city play a major role in the ability to establish the required coverage in the north half of the city and buildings in the south. Each network must be designed to fit the unique local conditions.

Right is a section of a map showing the water department and traffic management divisions have assets covered by a mesh network. It also shows that public safety will have mobile access to the data they need at street level.

Right is the propagation of a 5 GHz tower site that is providing capacity to a mesh network in a point to multipoint network configuration.

Note the impact of the hills on the lower corners and upper center on the coverage. 72 locations where considered and modeled before the final selection of 8 locations was made.

Without a detailed analysis and plan the city would be running the risk of making a large investment in a network that would not meet the goals and needs of the municipality.

These are just a few samples of the types of engineering plans and tools required to plan and deploy a municipal wireless network. Before you start the deployment insist on seeing this type of analysis pre and post deployment. This will ensure you have a complete and reliable network and you can maximize ROI.

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