Cell Site Analysis Truths & Myths
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Transcript of Cell Site Analysis Truths & Myths
What is CSA?
• Likely location of mobile phone(s) through examination of call data records, with or without radio frequency surveys
• Presented by expert witness, evidence being both relevant and reliable
• Introduced by Crown or defence in support of their case
No Calls – No Data
• Operators will in general only retain records relating to call activity
• GPRS Data is frequently available, giving data without call activity
• There are several exceptions including Home Location Register updates
Does your phone use nearest Cell Site?
• Not always, topography and local building clutter, may cause a distant site to provide a better service than the nearest site
• Also variable in the use of GPRS sites
• May vary with the hardware design
Can cell site pinpoint exact location?
• Cell Site Analysis cannot pinpoint precise locations of a mobile phone
• However, depending upon call data analysis, it may be possible to locate a mobile to within a few hundred metres
Is CSA an exact science?• The data we work with is
precise and therefore fact based and can be relied upon for accuracy
• It is often used to prove or disprove an inference and may be supported by other evidence i.e. ANPR, CCTV etc…
Does a Bus or Lorry Driving Past Affect Cell Site Signals?
• This generally does not apply as network operators employ techniques to avoid unnecessary handover between cells
• In certain situations however, if in close proximity to a stationary large vehicle, this could instigate handover
Directed Retry(Network Busy)
Could it be that the network was busy at the time of the call and a different cell site was used because of this?
•This can and does happen but only on certain networks, in busy areas at busy times!
Does the weather affect network readings?
• Very limited effects due to frequency of signals and low power cell sites
• Severe weather will affect all local cell sites equally
When are Temporary Cell Sites Used?
• To provide coverage or additional capacity at a specific event
• A common event for temporary cells is Glastonbury due to volume of people and rural setting which is not well covered.