Reality Check – Wireless Lessons from the Real-World
Environmental Effects on Wireless: Topographical Elements and Wireless Planning with Modeling and Design Systems
By John Welch – Apprion Wireless Advisor
This month we wrap up our Real–World Lessons Series on the "Environmental Effects on Wireless" with a look at the topographical elements effect on wireless deployments and an introduction to modeling software and the variables necessary to design a wireless system.
What impact do topographical elements have on wireless deployments?
Topographical and structural events include buildings, foliage, support structure and other elements that are a part of "the lay of the land". Topological structures may cause undesired attenuation, and the scattering or blocking of signals. Conversely, the effects of structure and ground topology may cause signal ducting, a phenomena which causes usable and perhaps interfering signal to be present at distances far greater than needed or desired.
In order to overcome the environmental effects of topology and structure, a design engineer has several excellent tools at his disposal. One such tool is model and design software. Modeling software is a good first step in wireless system planning and can help mitigate the effects of or, in many cases, take advantage of structure and topology. The modeling software programs contain logarithms for the propagation of signal for almost any given environment. The modeling programs allow for the input of structure. Important variables associated with that structure can be assumed then assigned, augmented or controlled.
Gathering accurate data is important. The boundary effects of radio frequency are complex and effected by not only structure in general but in the nuances of structure. Furthermore, structure may be dynamic in nature. Staging areas, equipment storage and rail areas are in constant flux, therefore, actual data in the form of real measurements (gathered in a "hands on" approach) is necessary for choosing exact equipment numbers, type and locations within almost any geographic area.
The result of the software program is an accurate "heat map" that predicts transceiver placement, transceivers' signal strengths of the targeted area, and includes a Bill of Materials. Regardless of the sophistication of modern modeling software, it should not be used alone or remotely for anything more than "ball park" equipment estimates. The accuracy of a modeling tool is at the mercy of the data input into the tool. Simply put, the more accurate the data, the more data points and the more on site measurements input into the program - the more reliable the results.
Conclusion
Environmental factors influence many variables, and an understanding of these variables allows the designer to:
- Identify the type of wireless services needed / system requirements
- Identify the types of product to fulfill the needed services
- Determine the minimum specification for each product
- Identify the specific need for security of data in the wireless and wired infrastructure
- Identify accurately the materials and man-hours necessary for the completion of a system
- Select the best possible locations for equipment
- Design a system which is reliable flexible and scalable.
 John Welch is a Senior Wireless Systems Engineer at Apprion. John has over thirty years experience in technology and engineering with RF, digital and analog devices and various wireless communication and video systems. He brings over 12 years of specialized wireless implementation and design experience with industrial, metropolitan and military wireless infrastructures and systems. Implementations to date include a last mile point to point wireless system under the 802.11 and 802.16 standards, a metropolitan wireless 802.11 deployment in the Auckland, New Zealand central business district and numerous industrial wireless network implementations at oil/gas, chemical and power facilities. In addition, John has developed patents and new inventions for wireless networking systems, antenna design and deployment methodologies.
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