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Propagation Studies

A propagation study is a computer simulated model of how a radio system should perform.  It gives an idea of the coverage, dead-spots and performance of a proposed radio system for planning purposes, as well as an existing system for diagnostic purposes. It's accuracy depends on many variables, and NO propagation model or study will take all of them into perfect account.

There are several different mathematical and scientific models used to determine "coverage" in a propagation study, and about as many ways to dissemble, hedge bets or oversell as there are people.  The most complete collection of technical details for determining how to run and present a propagation study is the Telecommunications Industry Association (TIA) Service Bulletin 88 or TSB-88 with addendum B.  However, there is no law or regulatory body that requires its use or the use of any specific method or modeling procedure. It is not a "standard" per se, but is the most complete, honest and well researched technical manual existent.

A short explanation of TSB-88 was published in MRT - Mobile Radio Technology - in Oct 1, 2004.

An extract:

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As wireless communications systems technology evolves, the complexity in determining compatibility between different types of modulation, separate or concurrent operational geographic areas and applications usage increases. There is a need to support the development of “best practices” in wireless system design, and TIA TSB-88-B provides a baseline metric.

To provide system managers with guidelines in determining compatibility between system types and even within single systems, TIA commissioned TSB-88-B (“the Bulletin”) to help address interference and frequency management issues between different types of technologies across different bands. It was prepared in part as a response to requests from user organizations and is intended to assist system designers as they work to design and implement new systems based on narrowband technologies and potentially incompatible types of system deployments. Some of the key issues that the document covers are the following:

• Design and frequency coordination of bandwidth-efficient narrowband technologies to be deployed as a result of the FCC “Spectrum Refarming” efforts;
• Quantification of the impact of new narrowband/bandwidth-efficient digital and analog technologies on current technologies;
• Migration and spectrum-management issues regarding the transition to narrowband/bandwidth-efficient digital and analog technologies. Including channel-spacing issues from 30 and 25 kHz to 15, 12.5, 7.5, and 6.25 kHz.

Additionally, the Bulletin provides preliminary information regarding narrowband and wideband data coverage issues in 25, 50, 100 and 150 kHz channel bandwidths for use in the 700-MHz band.

The overall focus of the standard is on methods of modeling, simulating and verifying Noise- and Interference-Limited Systems. This is important, because system managers have more choices than ever in terms of modulation techniques, and the number of entities involved in wireless communications systems continues to climb.

This Bulletin gives guidance on modeling and simulating narrowband/bandwidth-efficient technologies in a “post-Refarming” environment and provides performance guidelines for the same. It summarizes these in a “Spectrum Management Tool Kit” for use by frequency coordinators, systems engineers and system operators. In addition, there are guidelines for acceptance testing of completed systems to provide a comprehensive list of issues and techniques to determine acceptable coverage and performance for shipped systems.

For those interested in discussing TSB-88 in its various versions, a Yahoo Group has been created. The group name is TSB-88.

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We generally base our propagation studies on TSB-88 with the RadioSoft Comstudy v2.2 software, using the Longley-Rice model.

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