GSM Cell Selection Process

There are many aspects of GSM that provide useful guidance to understand processes that are performed regarding cell selection. These processes provide useful background help for cell site analysis. There is discussion at this blog about C1 and C2, but here are some other processes that rarely get a mention:

C1    Normal Cell Selection   This is the process of initial cell selection, searching all RF channels.

C2    Stored List Cell Selection   This is the process of initial cell selection where BCCH carrier information (e.g. a BA list) for the selected PLMN is stored in the MS.

C3    Camped Normally   This is where the MS is camped on a cell of the registered PLMN and may be able to make and receive calls. (Whether or not the MS can make and receive calls depends on the state within the location registration process). The MS monitors received level and the system information and checks whether cell reselection is needed.

C4    Normal Cell Reselection   This is where the MS has determined that cell reselection is needed and an attempt is being made to reselect a new cell.

C5    Choose Cell   This is where the MS has returned to idle mode from "connected mode" and is choosing a suitable cell to camp on.

C6    Any Cell Selection   This is where the MS is unable to camp normally on any cell of the selected PLMN, or cannot obtain service because of certain responses to a location registration (LR) attempt. It is searching for a cell of any PLMN to camp on (so that emergency calls can be made and warning notifications can be received).

C7    Camped on any Cell   This is where the MS has camped on a cell irrespective of its PLMN identity, so that emergency calls can be made and warning notifications can be received.

C8    Any Cell Reselection   This is where the MS is attempting to reselect a cell, irrespective of PLMN identity.

C9    Choose Any Cell   This is where the MS is returning to idle mode, after having entered "connected mode" from the "camped on any cell" state to make an emergency call. It is attempting to find an acceptable cell to camp on.

US Case: Daubert and Cell Site Analysis Maps

US Case: Daubert and Cell Site Analysis Maps

I having been an advocate, as many of you know, for many years for the use in evidence of network operator generated analogue and digital cellular radio maps (eg best server plots/density maps & single cell prediction plots/density maps). That is because they are a composite compiled from collection of visible and discrete detail relevant to the operator's predication. They illustrate, if you will, a visual demonstration of a radio coverage strategy in an area. A recent US Case dealt with cell site maps as part of the evidence. The case of the US v Benford discussed by Law Professor Susan Brenner, at her webblog, makes interesting reading indeed:

http://cyb3rcrim3.blogspot.com/2010/08/daubert-and-cell-site-data.html

There are examples of cell site maps here at Mobile Telephone Evidence (link below):

http://trewmte.blogspot.com/2009/08/cell-site-analysis-csa-images.html

US Case: Daubert and Cell Site Analysis Maps

US Case: Daubert and Cell Site Analysis Maps

I having been an advocate, as many of you know, for many years for the use in evidence of network operator generated analogue and digital cellular radio maps (eg best server plots/density maps & single cell prediction plots/density maps). That is because they are a composite compiled from collection of visible and discrete detail relevant to the operator's predication. They illustrate, if you will, a visual demonstration of a radio coverage strategy in an area. A recent US Case dealt with cell site maps as part of the evidence. The case of the US v Benford discussed by Law Professor Susan Brenner, at her webblog, makes interesting reading indeed:

http://cyb3rcrim3.blogspot.com/2010/08/daubert-and-cell-site-data.html

There are examples of cell site maps here at Mobile Telephone Evidence (link below):

http://trewmte.blogspot.com/2009/08/cell-site-analysis-csa-images.html

More on Cell Site Analysis: http://cellsiteanalysis.blogspot.com

Panorama and Cell Site Analysis

Panorama and Cell Site Analysis

The Omagh bombing 1998 and Panorama's investigation into the evidence and on cell site analysis and interception.

Reporter: John Ware.

Panorama: Omagh: What the Police Were Never Told

http://www.bbc.co.uk/iplayer/episode/b00dltt4/