700 MHz Band Channel Propagation Model

To provide telecommunications designers working in public safety communications with channel propagation models to use in simulation and testing.

The conversion from analog television in the United States, combined with the appeal for broadband pubic safety communications, has generated a lot of interest in the so-called 700 MHz band.  Thus, the 764-776 MHz and 794-806 MHz blocks have been dedicated to public safety while the others have been auctioned off to vendors for commercial services, and some blocks for joint use between the two.  This 700 MHz band offers excellent penetration through buildings, which is particularly useful for emergency responders and Enhanced 911 services.  For commercial vendors, the investment is motivated by the favorable propagation characteristics which extend coverage significantly for the same transmission power, translating into less infrastructure.

However before any network technology can be developed and deployed in this band, there is a need to characterize and understand the propagation environment in which it must operate.  In this effort we have derived such models, reduced from measurement campaigns conducted in eight different environments relevant to most usage scenarios, ranging from subterranean mine tunnels to an oil refinery, from mid-size to high-rise buildings, and also the urban-canyon environment.

The measurements were conducted in a large number of structures of varying dimension, shape, and function throughout the United States. The following table summarizes the environments:

Selected environments

1. Republica Plaza Building, Denver, CO

2. Denver Convention Center, Denver, CO

3. Hazel-Atlas subterranean mine tunnel, Antioch, CA

4. Greathouse subterranean mine tunnel, Antioch, CA

5. Horizon West apartment, Boulder, CO

6. Oil refinery, Commerce City, CO

7. NIST laboratory, Boulder, CO

8. Downtown Urban-Canyon, Denver, CO

Once the measurement campaigns were completed, the collected data was reduced to two separate channel models:

1. The first channel propagation model covers the first seven environments in the table.  Frequency and impulse responses can be generated from the model in any of the seven environments in MATLAB through the m-file below.  The input parameters are transmitter-receiver distance (m), bandwidth (GHz) and center frequency (GHz), maximum display time of the impulse response (ns), and the environment (specified as a number 1-7).
   

• Channel_response_generator.m

In addition, below is a firefighter demo showing video footage of the packet loss using the model during a transmission through three of the environments.

• Firefighter video demo in three environments

2. The second channel propagation model covers the last of the eight environments in the table.  It differs from the first in that an antenna array was used on the receiver end (as opposed to a single element) which allowed modeling the impulse response in the spatial domain as well as in the temporal domain.  A paper providing a full description of the model is currently under peer review.

This model also has a companion demo showing video footage of the packet loss during a transmission on site where the measurement campaign was actually conducted.

• Firefighter video demo in Downtown Denver