CSA Training Explanatory Diagram

CSA Training Explanatory Diagram

Given the huge range of knowledge and information needed for Cell Site Analysis (CSA) I have spent a considable amount of time creating many training sheets for the courses. The explanatory diagram below represents just some basic information acquired from radio tests and the meaning of the codes shown in the test screens.

This training document forms part of the procedure of a step-by-step guide in a long, long line of steps an trainee examiner will undertake and aids the trainee grasp the basics. Later the trainee will be shown additional information that isn't shown in the above diagram to extend knowledge and understanding.

Soon the examiner will come to realise that when I started out in an early thread in this blog identifying the elements in the GSM Radio DNA Bracelet I had a reason for doing that.  The data displayed in the screens (like the ones above) occur as a consequence of being assigned to one or more of the logical channels identified in the GSM Radio DNA Bracelet delivered by the physical channels of the radio system.

Cell Site Analysis (CSA) Images Part 2

Cell Site Analysis (CSA) Images Part 2
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It may interest those reading the discussions that I post that Cell Site Analysis (CSA) results from terrain and clutter analysis and radio test measurements can be defined in many different ways that can demonstrate particular elements of importance to a case.
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Image 5

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First we need to model (Image 5) the landscape that represents the geographical area and natural and manmade phenomenon in the surrounding area. In this case the scene of crime is close to a crossroads in the middle of small urban town.
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For the sake of comfort, juries rarely understand radio coverage that is verbally discussed but respond much better to discussion revolving around a visual aid presentation.
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Image 6

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In this particular case I want to show the jury that two microcells* were used and each microcell first needs to be defined (Image 6) to the jury so they have it clearly in their minds the origin and direction of the radio coverage that forms part of the discussion.
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In the first posting below (Cell Site Analysis (CSA) Images) coverage maps were shown defining large cell/macrocell coverage. Here, it is possible to refine and finesse coverage to a specific area with microcell coverage. Importantly, it is a really good idea to make sure the first image the jury sees represents the first radio coverage that a particular mobile phone has used that you want to talk about.
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Image 7

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The second microcell coverage (Image 7) should also be defined and distinguished. It's always best to remember with microcell coverage radio path is shaped in the same way as the High Street. Microcells don't go around corners.

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Image 8

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Finally the culmination of the presentation defines how the coverage from both microcells blend (Image 8 ) at particular points along the radio path.
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*Remember that mobile telephones need to be encouraged to use microcell coverage and the microcell location, coverage boundary, speed at which a mobile phone is moving and cell reselection cause system challenges that required the use of a new criterion that was introduced into the GSM Phase 2 Standards in 1996. Do you know what that criterion is called and how it works?
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Lastly, having mentioned microcell and large cell, the image below (Image 9) represents a visual indication about very important technical aspects concerning radio coverage and the layers depicted are often referred to in evidence. Indeed, if you care to read some of the Mobile Telephone Case Law you can find Appeal Courts referring to the importance of comprehending how far coverage extends.
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Image 9

Cell Site Analysis (CSA) Images

Cell Site Analysis (CSA) Images
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Cell Site Analysis (CSA) has had a good deal of airing recently here on the forum, so I thought you might like to see images from the work that I get involved.
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Image 1

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Image 1 is one slide from the training course material to introduce students to CSA when starting out discussing radio test measurements. It should be noted that this image represents less than 1% of all data acquired during radio test measurements.
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Image 2

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I thought it would be useful to include this Terrain and Clutter Map (Image 2) as I use this software to assist me in complex cases. Terrain and Clutter are discussed during training and as it was a topic of the discussion about UK Criminal Evidence Delays I thought it would be helpful to let forum members see that I am not referring to theoretical matters, terrain and clutter analysis actually takes place.

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Image 3

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It is essential to understand, when conducting radio test measurements, that just because radio signals can travel some distance from a particular Mast (Image 3) that coverage should not be dismissed or excluded. Operators set threshold limits, hard limits and boundary limits. It does not follow that just because a mobile is in the Green area shown in the Single Cell Prediction Map that the mobile will be excluded from using that coverage.

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Do you remember the discussion that I put up here CSA: Mobile Phones and Fringe Coverage?:
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Image 4

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Best serving coverage is often posed as the deal-clincher to suggest the mobile phone was most likely or consistent with being at a particular location. There can be numerous points that could (and I say 'could' advisedly) point to best server coverage being used but rarely does it come up in evidence because the radio content in evidence rarely gets disclosed these days.

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It is possible with best serving coverage that it can induce a negative outcome that may prevent calls taking place, so it is always important to see the other side of the coin, so to speak:
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GSM Radio Test Measurements Non-Dominance
GSM Radio Test Measurements
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I hope the above provides a further illustration of how smart and intelligent a science Cell Site Analysis really is and that by not applying it properly and dumbing down this art of this forensic science:

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- is not only a great loss to the law of evidence

- it reduces the examiner's/expert's knowledge and understanding about the subject with which they are dealing - mobile telephone evidence.

GSM Mast Installations (Density)

GSM Mast Installations (Density)

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When planning a cellular radio network there are many aspects to consider. The matter of radio technology and their frequencies (carriers) are but two examples. A relevance to be understood from these examples relate to what services may be obtained and delivered through these carriers? GSM for basic voice and text services and W-CDMA providing high data rates for video, gaming and conferencing etc.
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Germane and relevant to obtaining radio services are the radio access technologies needed for that - Masts and Antennas. In radio engineering terms, antennas provide the physical technology to access the services obtained in the radio coverage by use of transmitters and receivers, commonly referred to by the acronym TRXs. The Masts provide the physical location for the siting of the TRXs. An important aspect of Mast installations is knowing the potential customer numbers that will use the services obtained from them. The calculation used for the number of customers and the number of calls that can be handled by one Mast's TRXs is calculated using the Erlang formulae - the number of calls and time length of each call in an hour.
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Generally, though, to understand how Erlang can be used to determine the number of Masts and TRXs for an area let's just say there are 50,000 potential customers for a particular area. Let us also say to retain quality of service three sectors with 2 or 4 TRXs per sector, s222 or s444 respectively, are required. Let's also indicate that it is known that:

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1 TRX = 3 erlang, 2 TRXs = 5 erlang, 3 TRXs = 15 erlang, 4 TRXs = 20 erlang
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The relevant TRXs selected for this Mast installation scenario are 2 TRXs and 4 TRXs.
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Let:
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50,000 x 0.02 erlang, where 0.02 erlang is used per customer = **1000 erlang
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Each sector of an s444 may carry up to 20 erlang x 3 sectors = **60 erlang
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**1000/**60 = 16.7
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Therefore:
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16.7 (17) Mast installations would be needed where a configuration of TRXs s444
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or where
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33.4 (35) Mast installations would be needed where a configuration of TRX s222
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Remember the above is intended only to be illustrative so that it can be used to draw inferences about Masts installations and potential user numbers based upon the density of Masts in an area. An inference, such as, why a Mast further away than Masts sited closer to where a mobile station (MS) may be located routed the text message to the MS?

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There are a large number of issues to be considered but let us take iwo important issues to be considered are:

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- Point-to-Area predictions for terrestrial services 30 MHz to 3000 MHz

- Point-to-Point short message service (SMS)

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In relation to point-to-area it could be the height of buildings surrounding the MS may be a cause for a distant Mast routing a point-to-point SMS text message. Alternatively, it may be the routing of the point-to-point SMS text message from a distant Mast occurred because the MS, in the idle mode, was surrounded by Masts that were at call traffic capacity. Alternatively it could be because of a combination of both buildings and call traffic capacity.

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Knowing matters like these are very useful when dealing cell site analysis and a reason why they are incorporated into the Core Skills Knowledge of the TrewMTE training courses:

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GSM Cell Site Analysis Training Course

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Course One: GSM Core Skills Knowledge Course (CSA Part 1)

3-days training

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Course Two: GSM Cell Site Analysis Course (CSA Part 2)

3-days training
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Course Three: GSM Cell Site Analysis Course (CSA Part 3)

3-days training
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3G Cell Site Analysis Training Course

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Course One: 3G Core Skills Knowledge Course (CSA Part 1)

4-days training

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Course Two: 3G Cell Site Analysis Course (CSA Part 2)

3-days training

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Course Three: 3G Cell Site Analysis Course (CSA Part 3)

3-days training

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SIM Card Training

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GSM SIM Card Training Course

3-days training

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USIM/UICC Card Training

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3G USIM/UICC Training Course

3-days training

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GSM/3G Handset Examination Training

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GSM/3G Mobile Telephone Training Course

4-days training

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MTEB Mobile Telephone Evidence Diplomas (MTEdipl).