Interpreting Cellular Coverage for Transportation Applications

The process was developed for collecting and analyzing cellular coverage data by applying the results of analysis to analog cellular coverage in the state of Kansas. The type of analysis that is appropriate depends on the purpose for which the information is to be used. Two types of analyses were examined—fixed coverage and mobile coverage. Fixed coverage analysis is needed for such functions as automatic collision notification in which any individual cellular connection can occur from a fixed location. The study showed that the fixed cellular coverage of the Kansas state highway system was good. Only 0.4% of the highway by length had inadequate signal strength for using a 3-W phone (a typical car phone) and 1.7% for using a 0.6-W phone (a typical handheld unit). In contrast, the mobile coverage analysis identified numerous areas where a call from a moving vehicle would be severely limited in duration. This type of analysis is needed for applications such as communications for emergency medical services, for which a vehicle must sustain continuous communications. For example, more than 9% of the state highways by length cannot sustain a call of 30 min with a 0.6-W phone, and in some areas the percentage is considerably higher. For certain applications, this difference may simply translate to inconvenience, but for other purposes it can be very important. The results of the two types of analyses highlight different characteristics of the coverage footprint; one addresses absolute coverage and the other continuity of coverage. The results of the analysis technique relate more directly to the unique characteristics of wireless communications utilization in transportation applications.