In my analysis of the FCC’s 14th Mobile Competition Report (“14th Report”), I noted that the 14th Report lacked relevant data supporting its conclusion that spectrum below 1 GHz may provide competitive advantages. Among other things, I noted the 14th Report failed to consider elements affecting cell density other than propagation characteristics – elements such as capacity, geographic terrain, and typical power levels.
Now the FCC itself has confirmed the relevance of these factors to cell density. In a white paper released this week (“Public Safety Report”), the FCC published “a technical analysis of the capacity and performance of the public safety broadband network assuming that the National Broadband Plan recommendations concerning this network are implemented.” (Public Safety Report at 1.)
The Public Safety Report emphasizes that “sound network engineering principles” dictate high cell densities to maximize capacity. (See Public Safety Report at 5.) “Deploying greater numbers of cell sites achieves a greater aggregate capacity and higher overall level of spectral efficiency, consistent with Commission goals to achieve highest use for this scarce resource.” (Public Safety Report at 19.) Indeed, in analyzing a scenario in New York City (“NYC”), the Public Safety Report assumes there will be “considerably more than 3 times as many [700 MHz] cell sites” as were assumed necessary by the NYC Department of Information and Technology (Public Safety Report at 20). Although the propagation characteristics may have made the lower cell densities proposed by the NYC Department of Information and Technology possible, the Public Safety Report confirms that capacity concerns, rather than propagation characteristics, should dictate 700 MHz cell densities, at least in urban areas.
The Public Safety Report also recognizes that power limits inherent in mobile devices (due to concerns about human exposure to radiofrequency energy and adequate battery life) and desired data rates also limit cell sizes, regardless of favorable propagation characteristics. “The data rate and performance available to a device in a cellular broadband network is a function of how far it is from a transmission tower. . . . A network that must be capable of supporting a video device or other device that supports a high-data-rate application must therefore have smaller cell radii . . . .” (Public Safety Report at 13.) This is true in any geographic area, whether urban, suburban, or rural.
Although Dr. Peha was addressing the question in a different context, it’s still nice to see that the FCC’s Chief Technologist and I agree that propagation characteristics are only one of many relevant factors in mobile network design.
TAGS:
700 MHz Infrastructure public safety spectrum Wireless Mobile Broadband