Seemingly, not a day goes by and another governmental organization is announcing plans to build a wireless mesh network. The value of these networks is clear — communities can cost effectively provide high speed wireless voice and data communication services to their employees, residents and visitors. The challenges associated with realizing the benefits of these wireless networks are significant. With ten years of experience in wireless network development and implementation, Wireless Valley’s team of wireless industry experts have seen the benefits and pitfalls of these deployments and are helping customers address the challenges. The implementation of a wireless mesh network can be deceivingly simple. Install the access point (AP), plug it into an electrical source and turn it on. The APs automatically identify and connect to other APs in line of sight. In reality, this is rarely, if ever, the case with wireless deployments. Wireless Valley chief product officer, Dr. Roger Skidmore, points out, “If you do not consider and plan for all of the operational and environmental factors which impact each installation, the network will not have the necessary coverage and capacity to provide the quality of service expected by users. In many cases, this renders the network useless for many of the intended applications. This is especially detrimental if public safety or emergency medical teams hope to communicate using the network.” In order to properly set up a municipal wireless mesh network, planners need to consider the following three issues:
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- Environment – Many factors impact the performance of wireless signals. The construction and location of buildings, foliage and other natural and manmade obstructions can degrade or block wireless signals.
- Use of the network – The number of users accessing the network and the type of applications they will employ are important to consider. For example, significantly more users will access the network in a government office than in a parking lot. Also, applications such as public safety communications require high bandwidth and secure, uninterrupted service.
- Coverage and connection – One of the benefits of a mesh network is that all the APs can potentially share information with each other and transport traffic. However, if the traffic has to travel through too many APs in the mesh before it gets to a backhaul connection, the user will experience unacceptable delays. At the same time, it is important to make sure that there are enough connections available to each AP to ensure redundancy. If one or several APs are not operational, the network should still be able to function efficiently if it has been designed properly. Obviously, this ‘balancing act’ between coverage and connections can be quite difficult to determine.
The traditional way to plan and design wireless networks is through a site survey. This process involves powering up an AP in a part of the area to be covered, taking measurements of signal strength and coverage and then repeating the exercise until you have covered the entire region. This highly manual and time-consuming process is not practical for most municipal mesh projects, which are usually quite large in scope. Plus this method only enables planning for wireless coverage; it does not consider how the network will be used and what applications will be operating. The preferred alternative is a combination of computer-based design with a limited site survey used to optimize the design. This method enables a repeatable and scalable process in which users place APs and select which ones will have wired connections to the network, run simulations of the proposed network’s operation and adjust the design to address any identified coverage holes and capacity problems. Perhaps most important, this method understands and accounts for two items not considered in a site survey: the environmental and interference factors, which impact the wireless signal and the capacity and bandwidth needs of the network. Once the design is complete and the network implemented, the user can conduct a limited site survey to determine any adjustments that might be necessary. Properly planning a wireless mesh network will bring many benefits including more complete coverage, faster speed, strong reliability, ease of deployment, and lower implementation and operational costs.