Determining RF Coverage in Criminal Cases

When trying to establish that a defendant’s cellphone was in the area where a crime was committed, sometimes the government will use vague descriptions of cell site coverage areas. These usually consist of an arbitrary radius from the cell site that has not been scientifically determined. The prosecution typically will create a coverage area that is its “best case” and that encompasses the crime scene, thus “proving” that the defendant was in the area. When the prosecution provides this type of evidence, it is important for the defense to (1) obtain the call detail records and the cell site location information directly from the wireless operator, and (2) engage its own expert to create coverage plots that are based on a scientific approach. To determine the actual coverage of a cell, a combination of sophisticated radio frequency (RF) modeling and drive testing must be performed.