Cell Site Analysis Truths & Myths
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Cell Site Analysis Truth & Myths. We answer What is Cell Site Analysis? Do cell sites cover 35Km? How Many Cell Sites? Where could this happen? Does your phone use nearest Cell Site? Plus More
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Cell Site Analysis Truths & Myths
- 1. Cell Site Analysis Truths & Myths
- 2. 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
- 3. Do cell sites cover 35Km?
- 4. How Many Cell Sites?
- 5. Where could this happen?
- 6. Data Retention • Operators by law have to retain call data records for a minimum of 12 months
- 7. 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
- 8. 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
- 9. 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
- 10. 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…
- 11. 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
- 12. 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!
- 13. 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
- 14. 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.
- 15. How many SMS (text messages) are sent across all UK networks each month? • Over 12.5 BILLION!
Editor's Notes
- This is a commonly asked question in court. If it were true, then a cell site located in the centre of London would cover parts of neighbouring counties including Surrey, Kent, Essex, Berkshire and Hertfordshire! The first mobile networks were analogue (Cellnet/Vodafone) and deployed cell sites in this way hoping that they would each cover a city. Once mobile phones started to become popular, networks realised that they would need many more cell sites to cater for the volume of traffic.
- With the exponential growth of mobile phone sales and the introduction of digital GSM networks in the 1990’s, network operators got busy building many thousands of cell sites to provide sufficient capacity. Each GSM network operator has at least 10,000 cell sites including micro and pico cells.
- We can still experience extensive coverage from cell sites deployed in certain areas. Extremely rural areas or cell sites deployed on the coast can still provide service for many kilometres. In my experience I have encountered cells providing service in this type of area for 20Km. Networks purposely deploy cell sites at ports and channel crossings in order to attract roaming traffic.
- This does not mean that data is not available after 12 months!
- There are sensitive techniques for live cell site work which records much more data, but this is not available within historic call data records.
- Science by its very nature is not precise. The data provided to us is very accurate.