Several propagation models are used within the industry today, and no single model is suitable for every application. The model chosen depends largely on the application and the availability of site and GIS data. The accuracy of the propagation model ultimately determines the accuracy of the planning and optimization tools. Newfield works closely with clients to chose the most suitable models for their specific applications.

Propagation Model Classification

Propagation models can be broadly classified as follows:

• Empirical Models
  These models are described by equations derived from a statistical analysis of a large number of measurements. The models are simple and do not require very detailed information about the environment;
• Semi-empirical or Semi-deterministic Models
  These models are derived from the application of deterministic methods to generic rural or urban models. Calibration is commonly used to improve the models agreement with the measurement data. These models require more information than the empirical models but less than the deterministic models;
• Deterministic Models
  These models are based on the application of electromagnetic techniques to a site description using building and terrain databases.

A macrocell typically has a radius of between 1 and 30km whereas a microcell typically has a radius of between 0.1 and 1km. Empirical and semi-empirical models are suitable for macrocells with homogenous characteristics. Semi-empirical models may also be used for homogenous microcells. The deterministic models are in general too slow for use with macrocells but suitable for use with microcells.

Propagation Model Inputs

The geography of the environment affects radio propagation. The accuracy of a propagation prediction therefore depends not only on the accuracy of the model but also on the accuracy of the inputs to the model. The propagation model chosen determines the accuracy requirements of the GIS data inputs. The typical inputs that are available for use by propagation models are shown in Figure 1.

Figure 1 - Typical model inputs

Model Auditing

An organization’s planning and budget decisions are based on the output from the RF propagation modeling tool. It is essential to regularly evaluate that output to ensure its accuracy. This can be achieved by:

1. Performing path loss data collection and comparing the models with these independent data sets;
2. Auditing the current model parameters, the site and GIS data. This is essential to determine if the correct models and GIS data are being used.

Newfield has extensive experience in performing these tasks.

Model Selection

Newfield also has extensive experience in advising clients on all aspects of propagation model and GIS data selection. Once the output and input data accuracy has been determined, Newfield assists clients with model selection. Newfield can also develop and customize the guidelines and processes for their implementation and use.

Custom Model Creation

Newfield can create custom propagation models specifically for a client’s application. For example, Newfield designed a custom propagation model for a U.S. carrier that is deployed nation-wide.

Propagation Model Evaluations

Newfield can perform independent evaluations of different RF propagation models.

Propagation Modeling Services

• Guideline and Practice Development
• Creation of Custom Propagation Models for Cellular and PCS
• Technical Training
• Propagation Model Audits
• Propagation Modeling Tool Evaluation