Historic cell site analysis - Overview of principles and survey methodologies

The data stored on mobile phones is a common source of investigative and evidential material, but there may be further useful information available such as Call Detail (or Data) Records linked to the SIM card used, held by network operators for billing purposes. Historic Cell Site Analysis involves the analysis of these records, in conjunction with other information such as survey and geographic data, to determine areas where a phone may, or may not, have been when it was used. This paper gives an overview of how a handset and mobile phone network interact with each other along with a range of methodologies for data gathering and interpretation (including use of surveys). These methods are assessed, with advantages and disadvantages highlighted for each. Only 2G networks are discussed in detail; whilst there are differences in many aspects of network operation, general principles (such as the effects of terrain and relative cell selection) apply equally to 2G (GSM) and 3G (UMTS) phone